EPA-600/2-75-027
November 1975
Environmental  Protection Technology  Series
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                                          EPA-600/2-75-027 c.
                                          November 1975
SEWER FLOW MEASUREMENT - A STATE-OF-THE-ART ASSESSMENT
                         by

                  Philip E. Shelley
                George A."Kirkpatrick

   EG&G WASHINGTON ANALYTICAL SERVICES CENTER,  INC.
             Rockville, Maryland  20850
               Contract No. 68-03-0426
                   Project Officer

                  David  J. Cesareo
    Storm and Combined Sewer Section (Edison, N.J.)
            Wastewater Research Division
     Municipal Environmental Research Laboratory
               Cincinnati, Ohio  45268
     MUNICIPAL ENVIRONMENTAL RESEARCH LABORATORY
         OFFICE OF RESEARCH AND DEVELOPMENT
        U.S. ENVIRONMENTAL PROTECTION AGENCY
               CINCINNATI, OHIO  45268
                  EERU-TIX
RECEIVED
 APR  51989
EERU-TIX

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                                 75-0*1
                                DISCLAIMER
     This report has been reviewed by the Municipal Environmental Research
     Laboratory, U.S. Environmental Protection Agency, and approved for
     publication. Approval does not signify that  the contents necessarily
     reflect the views and policies of the U.S. Environmental Protection
     Agency, nor does mention of trade names or commercial products
     constitute endorsement or recommendation for  use.           i
e&i 2
XIT-UH33

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                             FOREWORD
Man and his environment must be protected from the adverse effects
of pesticides, radiation, noise, and. other forms of pollution, and
the unwise management of solid waste.  Efforts to protect the
environment require a focus that recognizes the interplay between
the components of our physical environment—air, water, and land.
The Municipal Environmental Research Laboratory contributes to this
multidisciplinary focus through programs engaged in

    •   studies on the effects of environmental contaminants
        on the biosphere, and

    •   a search for ways to prevent contamination and to
        recycle valuable resources.

The deleterious effects of storm and combined sewer overflows upon
the nation's waterways have become of increasing concern in recent
times.  Efforts to alleviate the problem depend upon accurate
characterization of these flows in both a quantity and quality sense.
This report presents a state-of-the-art survey of flow measuring
devices and techniques that either are, or might be, appropriate for
the quantitative measurement of stormwater and combined sewer flows
as well as other wastewater discharges, and will be of interest to
those who have a requirement for the measurement of such flows.
                                iii

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                             ABSTRACT


A brief review of the characteristics of storm and combined sewer
flows is given, followed by a general discussion of the need for
such flow measurement, the types of flow data required, and the
time element in flow data.  A discussion of desirable flow meas-
uring equipment characteristics presents both equipment requirements
as well as desirable features and includes an equipment evaluation
sheet that can be used for a particular application.

A compendium of over 70 different generic types of primary flow
measurement devices, arranged according to the fundamental physical
principles involved, is presented along with evaluations as to their
suitability for measurement of storm or combined sewer flows.  To
illustrate the implementation of the physical principles, a number
of commercially-available devices for flow measurement are briefly
de'scribed.

A review of selected U.S. Environmental Protection Agency project
experience in  flow measurement is presented along with a summary of
current and on-going research efforts.  Some thoughts on future areas
of research and development are also given.  This report was submitted
in fulfillment of Contract Number 68-03-0426 under  the sponsorship of
the  Office of  Research and Development, U.S. Environmental Protection
Agency.  Work  was completed in December 1974.
                                  IV

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                               CONTENTS
Section                                                           Page

    I      CONCLUSIONS ..... ............. .  .        1

   II      RECOMMENDATIONS ... ..... .  .........        3
         J                       .          '
  III      INTRODUCTION  . .  .  ........  .  ......  .        5

           Purpose and Scope .................        6
           General Nature of Storm and Combined
             Sewer Flows ...................        7
           Need for Flow Measurement .....  ..... ...       13
           Types of Flow Data Required .  . ..........       17

   IV      THE TIME ELEMENT IN FLOW DATA .....  ......       19

           Importance of the Time Element  ..........       19
           Continuous Recording of Flows  ...........       20
           Noncontinuous Flow Data ..............       21

    V      DESIRABLE EQUIPMENT CHARACTERISTICS  ...... .  .       23

           Primary Design Goals  ...............       23
           Secondary Design Goals  .....  .  ........       24
           Evaluation Parameters ..... .....  .....       25

   VI      METHODS OF FLOW DETERMINATION ......  .....       28

           General . ...... ... ......... ...       28
           Site Selection  .... ........  .  .....       29
           Gravimetric ....................       32
           Volumetric  . . .................  .       32
           Differential Pressure . . . .  ...........       36
           Variable Area ....... .....  .......       52
           Head - Area .......... .  .  ........       53
           Flow Velocity . .  .................       99
           Force - Displacement  ........  ..... .  .     112
           Force - Momentum  .  ..........  ......     121
           Thermal ...............  .  ......     123
           Electromagnetic ..... .............     128
           Acoustic  ................  .....     132
           Dilution  .................  ....     138
           Other ...............  .  .  .  .....     141
           Doppler ... ............  .......     143
           Optical .............  .........
                                   v

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                          CONTENTS (Cont'd)
Section
  VII
 VIII
                                                       Page

Electrostatic 	     145
Nuclear Resonance 	     147
Miscellaneous 	     147
Secondary Devices 	     148
Discussion ...... 	     150

REVIEW OF COMMERICALLY AVAILABLE EQUIPMENT  ....     154

Alphabetical List of Manufacturers	     156

SELECTED PROJECT EXPERIENCE 	     376

Characterization and Treatment of Combined
  Sewer Overflows	     376
Stream Pollution and Abatement From Combined
  Sewer Overflows - Bucyrus, Ohio	     378
Engineering Investigation of Sewer Overflow
  Problem - Roanoke, Virginia	     379
Combined Sewer Overflow Abatement Alternatives -
  Washington, D.C	     380
Urban Runoff Characteristics  ....  	     381
Storm and Combined Sewer Pollution Sources and
  Abatement - Atlanta, Georgia   	     382
Stormwater Problems and Control  in Sanitary
  Sewers - Oakland and Berkeley, Calif	     383
Dispatching System For Control of Combined
  Sewer Losses	     384
Preconstruction Evaluation of Combined Sewage
  Detention Facilities   	     385
Urban Storm Runoff and Combined  Sewer  Overflow
  Pollution - Sacramento, California   	     386
Storage and Treatment of Combined Sewer
  Overflows	     387
A Thermal Wave Flowmeter for Measuring Combined
  Sewer Flows	     388
Wastewater Flow Measurement In Sewers  Using
  Ultrasound	     389
Biological Treatment of Combined Sewer Overflow at
  Kenosha, Wisconsin	     390
Flow Augmenting  Effects of Additives on  Open
  Channel Flows  	     391
Surge Facility For Wet and Dry Weather Flow
  Control	     392
A Portable Device For Measuring  Wastewater Flow
  In Sewers	     393
                                   VI

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                         CONTENTS (Cont'd)
Section
                                                                  Page
           Joint Construction Sediment Control Project ....     394
           Combined Sewer Overflow Abatement Plan,
             Des Moines, Iowa  .  .  * . .	     395
           Computer Management of a Combined Sewer
             System	     395
           Characterization and Treatment of Urban
             Land Runoff	     397
           Other USEPA Projects	     398
           Projects by Other Federal Agencies  .........     399
           Projects Outside the United States  ..........     401

    IX     FUTURE AREAS OF RESEARCH AND DEVELOPMENT  .....     402

           General Research  	     403
           Applications Research  	  ...     405
           Demonstration Research	     406

     X     REFERENCES  .	     409

           Cited References  ......  	  ....     409
           Supplemental References	     415
                                 vii

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                       LIST OF ILLUSTRATIONS
Figure

   I
   2
   3
   4
   5
   6
   7
   8
   9
  10
  11
  12
  13

  14

  15
  16

  17

  18

  19

  20

  21
  22
  23
  24

  25
  26
  27
  28
  29

  30
  31
  32
Typical Storm Hyetograph and Hydrograph 	       9
Typical Vertical Velocity Profiles  	      12
Herschel Standard (Long) Venturi Meter Tube ....      37
Ball Flow Tube	      40
Typical Flow Nozzle Installation  	      43
Flow Nozzle Discharging to Atmosphere 	      44
Head Loss of Differential Pressure Meters 	      47
Pradtl-Pitot Impact Tube  	      51
Weir Terms and Their Relationships	      56
Various Sharp-Crested Weir Profiles   	      58
Compound Weir	      60
Examples of Broad-Crested Weir Shapes 	     .64
Type I Flume - Critical Flow Contraction Obtained
  by Small Width Reduction, Horizontal Bed  ....      68
Type II Flume - Critical Flow Contraction Obtained
  by Large Width Reduction, Horizontal Bed  ....      68
Type III Flume - Subcritical Flow Contraction
  Obtained By Small Increase In Bed Elevation,
  Horizontal Bed	      69
Type IV Flume - Supercritical Flow Contraction
  Obtained by Width Reduction and Sloping Bed ...      70
Type V Flume - Supercritical Flow Contraction
  Obtained by Width Reduction and Drop in Bed ...      70
Type VI Flume - Supercritical Flow Contraction
  Obtained By Steepening Slope   	      72
Configuration and Standard Nomenclature for
  Parshall Flumes 	      74
Various Cross-Section  Shapes of  Palmer-Bowlus
  Flumes	      79
Diskin Measuring Device 	      81
Rectangular Cutthroat  Flume  	  ....      84
San Dimas  Flumes	      87
Elements of a Trapezoidal  Supercritical
  Flow Flume	      89
Type HS, H, and HL Flumes	      92
Isometric  View of Type HS, H, and HL  Flumes  ....      93
Open Flow  Nozzle Discharge Profiles  	      96
California Pipe and  Trajectory Methods   	      98
Assembly Drawing of  a  Price  Type AA Current
  Meter	      11:L
Vane Meters	•  •  •      115
Target Meter	      *•*•*
Typical Hot-Tip Element Configurations   	      125
                                   Vlll

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                  LIST OF ILLUSTRATIONS (Cont'd)
Figure

  33

  34

  35

  36

  37
Components of an Electromagnetic Pipe
  Flowmeter 	
Components of an Electromagnetic Velocity
  Probe	 . .
Physical Arrangements of Acoustic Depth
  Sensors ...... 	 .
Physical Arrangements of Acoustic Velocity
  Sensors	
Chemical Dilution Methods 	 . .
130

131

135

13,6
140
                                 ix

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                            LIST OF TABLES
Table                                                             Page

   1       Flow Measurement Equipment Checklist	 .       27
   2       Flow Meter Categorization 	       30
   3       Gravimetric Meter Evaluation (All Types)  	       33
   4       Volumetric Meter Evaluation (All Types) 	       35
   5       Venturi Tube Meter Evaluation	       39
   6       Ball Tube Meter Evaluation	       42
   7       Flow Nozzle Meter Evaluation  	       45
   8       Orifice Meter Evaluation  	       48
   9       Elbow Meter Evaluation	       50
  10       Slope-Area Method Evaluation  	       55
  •ll       Sharp-Crested Weir Evaluation (All Profiles)  ...       62
  12       Broad-Crested Weir Evaluation 	       66
  13       Subcritical (Venturi) Flume Evaluation  	       73
  14       Standard Parshall Flume Dimensions
             and Capacities  .	       76
  15       Parshall Flume Evaluation 	       77
  16       Palmer-Bowlus Flume Evaluation  	       80
  17       Diskin Device Evaluation  	 	       83
  18       Cutthroat Flume Evaluation  	       85
  19       San Dimas Flume Evaluation  	       88
  20       Trapezoidal Flume Evaluation  	       91
  21       Type HS, H, and HL Flume Evaluation	       94
  22       Open Flow Nozzle Evaluation	       97
  23       Float Velocity Evaluation 	      103
  24       Tracer Velocity Evaluation  	      105
  25       Vortex-Velocity Meter Evaluation   	      106
  26       Eddy-Shedding Meter Evaluation  	      108
  27       Turbine Meter Evaluation  	      109
  28       Rotating-Element Meter Evaluation  	      113
  29       Vane Deflection Meter Evaluation	      117
  30       Hydrometric Pendulum Evaluation	      118
  31       Target Meter Evaluation 	      120
  32       Force Momentum Meter Evaluation	      124
  33       Hot-Tip Meter Evaluation  	      127
  34       Thermal Boundary Layer Meter Evaluation 	      129
  35       'Electromagnetic Flowmeter Evaluation  	      133
  36       Acoustic Meter Evaluation 	      139
  37       Dilution Method Evaluation  	      142
  38       Doppler Meter Evaluation  	      144
  39       Optical Meter Evaluation  	      146
  40       Flowmeter Evaluation Summary  	      151
  41       Comparison of Most Popular Primary Devices
             or Techniques	      152

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                            ACKNOWLEDGMENTS
The cooperation and support of the commercial manufacturers and
suppliers of flow measuring equipment and their representatives
is acknowledged with sincere thanks.  They supplied information
about their current products and proposed new developments, took
time to answer questions and provide operational insights, and
made the preparation bf Section VII of this report possible,  All
equipment illustrations were provided by the respective manufacturers,
and apprectiation for their use in this report is hereby acknowledged.

Appreciation must also be expressed to all of the project engineers
and research workers who took time to discuss various aspects of
their work, to share insights and field experiences, and to offer
suggestions about the use of certain equipment.         '

Finally, the support of this effort by the Storm and Combined
Sewer Section (Edison, New Jersey), Wastewater Research Division,
Municipal Environmental Research Laboratory, Cincinnati, Ohio,
and especially Mr. David J. Cesareo, Project Officer, and the
other manuscript reviewers is acknowledged with gratitude.
                                  xi

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                             SECTION I

                            CONCLUSIONS
1.  A flowmeter is one tool of several that must be employed for the
    characterization of a wastewater stream.  Its selection must be
    based upon consideration of the overall flow measurement- program
    to be undertaken, the nature of the flows to be measured,  the
    physical characteristics of the flow measurement sites, and the
    degree of accuracy required, among other factors.

2.  In view of the large number of highly variable parameters asso-
    ciated with the storm and combined sewer application, no single
    flowmeter can exist that is universally applicable with equal  .
    efficacy.  Some requirements are conflicting, e.g., an open drain-
    age ditch versus a closed conduit deep underground, and a careful
    series of trade-off studies is required in order to arrive at a
    "best" selection for a particular program and site.

3.  There are over 70 generic devices and methods that can be used for
    determining wastewater flows, and they were reviewed and discussed.

4.  The proper selection of flow measurement sites can be as important
    as the selection of methods and equipment.  A clear understanding
    'of the data requirements and ultimate use is necessary, as is a
    familiarity-with the sewer system to be examined.

5.  Of the over 120 prospective manufacturers of liquid flow measuring
    equipment which were contacted, none has a flow measurement product
    line that is specifically designed for the storm and combined sewer
    application.

6.  Where large flows are to be measured with fairly high accuracy,
    considerable expense in terms of initial equipment cost, site
    preparation and  installation, and operator training and maintenance
    is involved; fifty to one hundred thousand dollars should not be
    considered atypical.

7.  There are measurement sites where no presently available equipment
    can operate unattended for  long at a high degree of accuracy
    (better  than ±5% of full scale).

8.  The most consistently reliable flow measurement  data have been
    taken at sites where the equipment has been  calibrated in place
    over the entire  range of flows anticipated.

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9.   Field experience in wastewater flow measurement was reviewed, and
     in most instances errors of greater than 10% seem to be the rule.
     It is not at all uncommon to find readings that differ from spot
     field checks by from 50 to 200 percent.  Some wastewater dis-
     charge data are of such poor quality as to be virtually useless.

10.  Flow measurement research efforts within the United States were
     reviewed.  Very few of those outside the USEPA are addressed to
     the storm and combined sewer problem as presented here, and it
     would appear that few, if any, that are not so oriented will pro-
     duce technology fall-outs that will benefit the solution of the
     problem at hand.

11.  The technological state-of-the-art, especially in electronics,
     is advancing very rapidly at the present time, and capabilities
     are emerging that until now were either impossible or prohibi-
     tively expensive.  Examples include improved pressure sensors,
     solid state and integrated circuitry advances (and price reduc-
     tions) that facilitate control and computational functions,
     quartz crystal timers that offer accuracy improvements measured
     in orders of magnitude, improvements in electronic recorders,
     etc.  As a result,  both new products and improvements to old
     ones are continually appearing.

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                            SECTION II

                         RECOMMENDATIONS
1.  It is recommended that flow measurement accuracy requirements  be
    very carefully considered with an eye to optimizing the accuracy
    of determination of total pollutant discharge.   Very high accura-
    cies over very wide ranges may not be necessary for all purposes
    and will certainly be expensive to achieve.

2.  Where possible, it is recommended that flow measurement equipment
    be calibrated in place at the site 'where the data are to be col-
    lected.  Maintenance should be performed such that conditions  do
    not deviate greatly from those at the time of calibration.

3.  Use and maintenance of complex, sophisticated flow measurement
    equipment should not be entrusted to well-meaning but untrained
    personnel.  Proper training of operator personnel is recommended
    as it will produce long-term benefits.

4.  It is recommended that the flow measurement site be chosen with
    great care.  It can be as poor an error in judgement to choose a
    site that will not yield the desired data simply because of equip-
    ment availability as it is to attempt to apply the wrong equipment
    at a site that is truly important.

5. , In view of the immediate requirements for storm and combined sewer
    discharge data for surveys, computer model calibration and veri-
    fication, infiltration/inflow studies, and the like, the most
    urgent need is for suitable portable devices that are capable  of
    unattended operation.  It is strongly recommended that a program
    to develop such devices be initiated with special emphasis on:

         •  Automated Chemical Dilution Devices

         •  Ultrasonic Devices

         •  Hybrid Flumes

6.  There has been very little opportunity to evaluate, flow measure-
    ment equipment suitable for storm and combined sewer applications
    in a side-by-side fashion under somewhat controlled conditions.
    It is strongly recommended that a suitable facility be identified
    and used to gather comparative data with emphasis on the more
    promising portable devices.

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8.
9.
There are a number of flow measurement devices that have either
recently become available or are about to be introduced and that
offer considerable promise in a storm and combined sewer applica-
tion.  It is recommended that a program of demonstration testing
be initiated to include such devices as:

     •  Venturi Meter/Flumes

     •  Combination Thermal Flowmeters

     •  High Range Open Flow Nozzles

This study was essentially limited to developments and practices
within the United States.  It is recommended that a survey of
foreign research and development activities and storm and combined
sewer flow measurement practices be conducted.

Because of the burgeoning nature of the present state of the art
and increasing concern over environmental contamination caused by
storm and combined sewer discharges, this report should not be
considered a final, enduring document.  It is recommended that it
be expanded and updated within two years.

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                            SECTION III

                           INTRODUCTION
Since almost the beginning of civilization,  man has recognized the need
to determine liquid flow rates, quantities,  or stages,  and his first
efforts'-were probably directed towards survival during  floods and trans-
portation by water craft.  Demands for water supply, irrigation,  navi-
gation, and waterpower all accentuated the need for flow measurement.
It is known that the ancient Babylonians and Egyptians  used some means
of water accounting to individual land holders from their extensive
irrigation systems.  The procedures used were possibly  taken from
methods used earlier in eastern Asia.

The River Nile of Egypt has probably been studied for a longer period
of time than any other river in the world.  The crops of the Nile Valley
are dependent upon annual flooding by the river, and thus, annual yields
are proportional to fluctuation in stage.  In view of this, taxes were
levied based upon -maximum flood height.  An interesting compilation of
data concerning flood records of the Nile has been prepared by Jarvis  (1)
Mention of the annual rises of the Nile date back to between 3000 and
3500 B.C., and known flood marks extend as far back as  approximately
1800 B.C.

One of the most complete records of early flow measurement systems is
that by Sextus Julius Frontinus (2), who was the Water  Commissioner of
Rome in the latter part of the first century.  The quantity of water
delivered to each user in the Roman system was determined entirely on
the area of spouts through which the flow was discharged; thus, these
could be considered as early forms of flow nozzles.

The earliest attempts at flow velocity measurement were undoubtedly
made by timing the travel of floating debris over some measured dis-
tance.  Hero of Alexandria's proposal, which was written about 62 A.D.,
called for using a sun dial for timing his operation.  In the 15th Cen-
tury, Leonardo da Vinci offered an improvement by attaching an inflated
pig's bladder to one end of a pole and a stone to the other, thus
achieving an integrating float of sorts.  Frazier (3) provides an in-
teresting account of a physician's plan for a deflection water current
meter, circa 1610.  In the middle of the 17th Century,  Evangelista
Torricelli developed the relation that the rate at which water was dis-
charged from an orifice varied with the square root of the height of
the water surface in the supply tank.  Subsequent improvements in the
state of the art included Henri Pitot's impact tube developed in 1732,
Reinhard Woltman's propeller-type current meter invented around 1790,

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 and  the work of Giovanni  Venturi  on  the relations between the velocities
 and  pressures of fluids flowing through converging and diverging tubes
 reported  in 1797.

 The  history of improvements  in flow  measurement devices/techniques is
 far  too extensive to be reported  here.   The reader interested in the
 subject is  referred to some  of the selected additional references
 listed in Section XI.  It suffices to say that today we have a plethora
 of liquid flow measurement devices and  techniques available, and it is
 to them that the remainder of this report will be directed.

 PURPOSE AND SCOPE

 Among  man's first waterworks projects were aqueducts to convey water
 into his  cities for consumption and  sewers to collect and dispose of
 nuisance  stormwater.  As  early urbanization continued, these first
 storm  drains  also became  the transport media for domestic wastewater-
 and, in effect,  the first combined sewers.  For convenience and expe-
 diency, these sewers simply  emptied  into the nearest natural water-
 course.   As urbanization  continued,  the  dry-weather flow in these
 sewers became a public nuisance,  and wastewater treatment was born.
 Sanitary  engineering practices and procedures were developed, all
 based  upon  characterizing and treating this dry-weather or sanitary
 sewage flow.   The construction of separate storm and sanitary sewer
 systems in  many cities was merely an extension of this trend.  The
 pollutional characteristics of stormwater were unrecognized, and it
 continued to  be simply discharged into the nearest natural stream.

 The  phenomenal growth of  urban areas in recent times and the rapid ex-
 pansion of  industrial operations  to meet society's ever increasing
 demands for more goods, energy, etc., have heightened the pollutional
 potential of man's existence and  have contributed to his increasing
 awareness of  and concern  for his  environment.  One of the impacts of
 the  population explosion  is that  sanitary engineering practices that
 appeared  tolerable even as recently as a few decades ago are no longer
 acceptable  today  in many  locales.   The pollutional effects of storm-
water  and combined sewer  overflows on receiving water quality are be-
 coming less and  less tolerable and a research program to mitigate or
 ameliorate  the situation has been underway at the USEPA (and its
 predecessor- agencies)  for the last several years.

 In order  to characterize  these stormwater and combined sewer overflows
 and  to facilitate the development, demonstration,  and evaluation of
 treatment and  control systems for combating the problem,  it is neces-
 sary to have available accurate and reliable means of determining the
 quantity and quality of the flows in question.   Both the quantity1 and
 quality of urban stormwater runoff are highly variable and transient

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in nature, being dependent upon meteorological and climatological fac-
tors, topography, hydraulic characteristics of the surface and sub-
surface conduits, the nature of the antecedent period, and the land use
activities and housekeeping practices employed.  Conventional flow meas-
urement devices and techniques have been developed mainly for the rela-
tively steady-state flows as found in irrigation canals, sanitary sewers,
and large streams and not for the highly varying surges encountered in
storm and combined sewers.

This report is intended""1-to present a current review of the state of the
art and assessment of flow measurement devices and techniques,.  These
are described and evaluated in terms of their suitability for use in
storm and combined sewer applications.  However, a device or technique
which is suitable for such use will most likely suffice for any other
wastewater flow measurement application as well.  By collecting and
presenting such a review, it is hoped that shortcomings and limitations
of some extant devices and techniques for storm and combined sewer ap-
plications can be overcome and that this report can serve as a spring-
board for improvements.

GENERAL NATURE OF STORM AND COMBINED SEWER FLOWS

Storm Sewer Flows

Although storm sewers are basically designed to carry storm runoff,
during periods of no rainfall they often carry a small but significant
flow (dry weather flow).  This may be flow from ground water, or "base
flow", which gains access to the sewer from unpaved .stream courses.
Such base flow may appear as runoff from parks or from suburban areas
where there are open drains leading to the storm sewer.  Unfortunately,
much of the dry weather flow in storm sewers is composed of domestic ....
sewage or industrial wastes or both.  Where municipal ordinances con-
cerning connections to sewers are lax or are not rigidly enforced, it
appears reasonably certain that unauthorized connections to storm sew-
ers will appear.  In some cases, the runoff from septic tanks is carried
to them.  Connections for the discharge of swimming pools, foundation
drains, sump pumps, cooling water, and pretreated industrial process
water to storm sewers are permitted in many municipalities and con-
tribute ,to flow during periods of no rainfall.  In some areas, sewers
classed as storm sewers are, in fact, sanitary or industrial waste
sewers due to the unauthorized or inappropriate connections made to
them.  This may become so aggravated that a continuous flow of sanitary
or industrial wastes, or both, flows into the receiving stream.

The "dry-weather" portion of storm sewer flow may vary significantly
with time.  Probably the most steady flow, and constant character of
pollutants therein, occurs in storm sewers when all flow is base flow

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derived from ground water.  Because of the slow movement of water
through the ground, changes in flow and concentration of pollutants
occur only during relatively long time periods.  Where unauthorized
connections of domestic sewage and industrial waste lines to storm sew-
ers are found, rapid fluctuations with time may occur.  The domestic
sewage constituent varies with time of day, with season of year,  and
probably over long-term periods.  Industrial wastes vary with specific
processes and industries.  Very rapid changes may occur with plant
shift changes and with process dynamics.  Conditions on weekends  and
holidays may be very different from those on regular work days.

Storm runoff is the excess rainfall which runs off the ground surface
after losses resulting from infiltration to ground water, evaporation,
transpiration by vegetation, and ponding occur.  A small portion  of
the rainfall is held in depression storage, resulting from small  ir-
regularities in the land surface.  The quantity, or rate of flow, of
storm runoff varies with intensity, duration, and areal distribution
of rainfall; character of Jihe'soil and plant life; season of the  year;
size, shape and slope of the drainage basin; and other factors.   Ground
seepage loss varies during the storm, becoming less as the ground ab-
sorbs the water.  The period of time since the previous, or antecedent,
rainfall significantly affects the storm runoff.

In general, storm runoff is intermittent in accordance with the rain-
fall pattern for the area.  It is also highly variable from storm to
storm and during a. particular storm.  The time-discharge relationship,
or hydrograph, of a typical storm, with its synchronous time-
precipitation relationship, or hyetograph, is illustrated in Figure 1.
The meanings of various parameters given in the figure are:
     R
      av
- Rainfall retained on the permeable portion of the
  drainage basin, and not available for runoff.

- Precipitation in excess of that infiltrated into
  the ground, plus that retained on the surface.
  Equals the volume of flood runoff.

- Average infiltration of the ground during the
  storm.  Infiltration capacity decreases as the
  storm progresses.

- Period of rise from the beginning of storm runoff
  to peak of the hydrograph.

- Time from center of gravity of rainfall excess
  to the hydrograph peak (lag time).

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     b.,b-  - Base line separating groundwater discharge from
              surface runoff.

The total volume of runoff for a particular storm is represented by the
areas between the base line and the hydrograph.

To illustrate some of the problems in measuring storm runoff in small
basins, peak flows exceeding 85 cubic meters per second per 260 hectares
(3,000 cfs per square mile) have been observed.  Lag times (t ), for
example, of 15 minutes to a hydrograph peak of about 28 cubic meters per
second (1000 cfs) from a 600-hectare (2.3 sq mi) area are not uncommon.
With rapid changes in the flow such as this, only those flow measure-
ment methods which are responsive to such changes can be used.  The
high rates of flow, with accompanying high velocities, further limit
the usable flow measuring equipment methods.

The maximum rate of flow in an underground storm sewer is governed by
its design capacity.  This capacity is based on the flow due to a storm
occurring, on the average, once in a selected number of years (recur-
rence interval).  Usually, a recurrence interval not greater than
10 years is selected for the design of underground storm sewers.  As
a result, the design capacity of the sewer is sometimes exceeded, re-
sulting in surcharging and flooding of the overlying surface.  Under
these conditions, measurement of surface flow must be added to meas-
urement of surcharged flow in the sewer to obtain total flow.

The poor quality of stormwater draining from the urban environment has
a significant effect on the choice of suitable flow measurement equip-
ment and methods.  Washings from the sidewalks, streets, alleys, and
catch basins are a part of the runoff and include significant amounts
of human and animal refuse.  In industrial areas, chemicals, fertilizers,
coal, ores, and other products are stockpiled exposed to rainfall, so
that a significant quantity of these materials appears in the runoff.
Extreme quantities of organic materials such as leaves and grass cut-
tings often appear in storm sewers.  Often during storms large boards,
limbs, rocks, and every imaginable kind of debris appear in the sewers,
probably as a result of breaks in the sewers or accessory equipment
designed to screen out the larger items.

Observation and experience have demonstrated that the heaviest con-
centration of suspended solids during periods of storm runoff usually
occurs during the early part of the storm.  At this time, the stage
is rising, and accumulated dry-weather solid residue is being flushed
from the sewers and washed and eroded from the tributary land areas.
As runoff recedes, the sewer and land area surfaces exposed to flow
are reduced; the flow velocities which serve to flush and erode are
decreased; and the more easily dislodged solids have been acted upon.
                                   10

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 This pattern of variation may not  occur  during  a  period  of  storm run-
 off which, immediately follows a previous storm  runoff period because
 the land surface and sewer  lines are. relatively clean.

 Pollutants which may be injurious  to equipment, and are  derived from
 point sources such as those from stockpile  drainage, vary at the
 sampling location with time of travel from  the  source to the point of
 observation.   Maximum concentration  may  occur after the  peak of storm
 runoff.   It is conceivable  that there would be  no contribution from
 some point sources during a specific storm  because of areal variation
 of  rainfall in the basin.

 Both velocity and the concentration  of suspended  solids  in storm sew-
 ers vary with position in the sewer  cross-section.  The  manner in which
 velocity is distributed in  the sewer section seriously affects those
 flow measurement methods  which require independent determination of
 average  velocity.   Some typical velocity profiles are shown in Figure 2.
 With open-channel flow, higher velocities are usually found near the
 surface  and lower velocities  near  the bottom.  Average velocity in the
 vertical is at about 0.6  depth.  Velocities are higher near the center
 of  the pipe or conduit than near the outer boundaries.   When the conduit
 is  surcharged and is flowing  full, lines of equal velocity tend to be
 concentric, with the higher velocity near the center.  On horizontal
 curves,  higher velocities are on the outside of the curve due to the
 centrifugal inertia force.  Because  the  effect of curvature on flow
 often continues  downstream  for a considerable distance,  a normal dis-
 tribution of  velocity is not  found on a  curve, or downstream for a
 distance of several sewer widths.

 Suspended  solids heavier  than water have their lowest concentration
 near the surface,  and  the concentration  increases with depth.   A "bed
 load", composed  almost  entirely  of heavier solids, may occur near the
 bottom of  the sewer.   This may  "slide" along the bottom or,  with in-
 sufficient  flow velocity, may  rest on  the bottom.   As the velocity and
 turbulence  increase,  the "bed  load" may be,picked up and suspended in
 the  sewage.   At  the beginning of storm runoff, as water picks  up solids
which have  accumulated in the sewer upstream during periods  of no rain-
 fall,  the flow may be  composed largely of sewage solids,  or  bed load,
which appears  to be pushed ahead by the water.

 Suspended materials lighter than water, such as oils and  grease,  float
 on the surface - as do leaves, limbs, boards,  and  some cloth and paper
materials.  Other small, light particles are moved randomly  within the
 flow by  turbulence.  Larger, heavier suspended and floating  solids
 tend to move  to the outside of a horizontal  curve, following the stream
 line's of higher velocity.
                                  11

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                                    if""- -*•- .*• r-y:
         LAMINAR
TURBULENT
a)  FULL  PIPE FLOWING  UNDER PRESSURE
                    7/7
b)  SOME  OPEN CHANNEL  FLOW PROFILES
      Figure 2.  Typical Vertical Velocity Profiles
                         12

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Combined Sewer Flows

Combined sewers are designed to carry both stormwater and sanitary
sewage and/or industrial wastes.  Therefore, except for their sanitary
and industrial sewage components (dry-weather flow]), they have the same
flow characteristics as storm sewers.  As indicated earlier, where mu-
nicipal ordinances are lax or not enforced with respect to sanitary or
industrial sewer connections to them, storm sewers are little different
from combined sewers.  As combined sewers are designed, dry-weather
flow generally includes only a small portion of the total sewer flow.
However, due to overloading in many rapidly developing areas, the dry-
weather flow sometimes requires a much larger percentage of total
capacity.  Furthermore, stormwater runoff usually increases dramatically
with urbanization.

Because the design, or available, capacity of combined sewers for car-
rying stormwater is probably less than is usually provided in storm
sewers, they either become surcharged more frequently, or the excess
flow is diverted to overflow lines.

NEED FOR FLOW MEASUREMENT                                 '

Measurements of quantity of flow, usually in conjunction with sampling
for flow quality, are essential to nearly all aspects of water pollu-
tion control.  Research, planning, design, operation and maintenance,
and enforcement of pertinent laws - all are activities which rely on
flow measurement for their effective conduct.  For some activities,
very precise, time synchronized, continuous flow records are needed.
With others, occasional, fairly rough estimates of flow may suffice.

Research

A principal research activity is the development of an extensive backlog
of data to characterize the various types of wastewater - e.g., sanitary
and industrial wastes, stormwater, combined sewage, and effluents from
treatment plants.  The quantity and rate of sanitary sewage flow from
individual homes, apartments, and commercial buildings, as found in
various cities and geographic locations, provide data useful for many .
purposes.  Similarly, measurement of the flow of wastes from specific
industrial processes provides general information concerning the char-
acter of such industrial wastes.  Characterization of stormwater and
combined sewage with respect to geographic location, population density,
land use, and other parameters, makes reasonably accurate estimation for
unmeasured areas possible.  Similarly, flow records from a network of
natural streams throughout the country, such as those maintained by the
U.S. Geological Survey, make possible the characterization of ungaged
streams which may be required to receive wastewaters.
                                   13

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Mathematical models of the relationships between rainfall, runoff, basin
characteristics, and concentration of pollutants in the runoff, such as
the Storm Water Management Model of the TJSEPA, are being developed.
The principal limiting factor-in the development and testing of such
models has been the scarcity of satisfactory data on the quantity and
quality of runoff in urban areas.  Although these models can perform a
very useful function in synthesizing flow records, they do not fully
substitute for actual flow measurements and records.  For example, ap-
plication of a model to an unfamiliar area needs verification by actual
records, and adjustments to the model are often indicated.

Planning

The availability of reasonably accurate and long-term records of flow
is a basic requirement for planning new or expanded systems of sewers,
o'r systems for the control and/or treatment of stormwater and combined
sewage.  Such records, with records of water quality, are required to
define the scope of the problem to be solved, and to make necessary
decisions concerning the type, size, number, and location of facilities
required.

A knowledge of existing flow conditions, plus knowledge of existing
pollutant concentrations, is indicative of conditions to be expected
in the future, and thus serves to define the problem.  For example, in-
filtration into sewers is a common problem which must be addressed to
avoid excessive construction and operational costs.  Flow measurements
can serve to locate the approximate source and quantity of such
infiltration.

For storm and combined sewer systems, knowledge of the number, fre-
quency, and pollutant loadings (the product of quantity and concentra-
tion) of overflows is necessary to evaluate their impact on the
receiving stream.  Thus, the extent and seriousness of .the problem can
be determined.

,In many cases, the sources and movement of stormwater pollutants are not
obvious.  They may originate partly through rain and snowfall over a
city; from the surfaces of buildings, streets, vacant land, construc-
tion sites, parking lots, and yards in urban runoff; and in the sewer
system.  Often the sources and movements of such pollutants can be
determine^ through a systematic program of flow measurement and sam-
pling, thus outlining the necessary extent of a pollution control
system or program.

A significant number of procedures and facility types are available to
management for the control of pollution due to stormwater and combined
sewage.  In general, these include methods for controlling the quantity
of flow, and those for treating, or improving the quality, of wastewater.
                                    14

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  Quantity of stormwater can be controlled at the source by increasing
  infiltration to groundwater, and can be controlled in the sewer system
  itself by reducing infiltration to the system, by using the maximum
  capacity of the system itself for storage, and by other procedures.
  Facilities for temporary storage of wastewater outside of the sewer
  system can be provided.

  A number of physical,  chemical, combinations of physical-chemical, and
  biological methods have been considered in the Storm and Combined Sewer
  Pollution Control Program of the USEPA for treatment of stormwater and
  combined sewage.   In most cases, some type of control such as reduction
  of instantaneous  peak  flows is essential for practical application of
  treatment methods.  Selection of suitable facilities and procedures
  for control of peak flows depends upon the availability of storm hydro-
  graph records.

  Character of storm runoff as influenced by geographic differences in
  storm patterns,  intensity, and frequency is defined by records of
  flow and is the basis  for decision on the type of pollution control
  system to be used.  As stated by Lager and Smith (5), "Stofim 0$ high.
  •inte.m>wt>  a £ tow 
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and size of units, the quantity of chemicals, and the design of equip-
ment for chemical handling must be based on records of peak flow and
volume of flow, as modified by storage.

Operation and Maintenance

Although operational guides and maintenance procedures are often based
on historical records of flow, flow records obtained on a "real-time"
basis may be more useful for operational purposes.  Where temporary
storage within an extensive system of sewers is controlled by computer,
flows at remote locations may be sensed and telemetered to the com-
puter.  The system can thus be regulated to more fully utilize its
total capacity.  If temporary offline storage is to be utilized within
a combined sewer system, a preselected rate of flow, or stage, in the
sewer could serve to initiate diversion to storage.  Efficient operation
of systems for wastewater pollution control must depend upon measure-
ment and sampling of flows.  In fact, operation of the large-scale,
high-rate systems that may often be required for control and treatment
of stormwater and combined sewage will not be possible without coordi-
nated systems of flow measurement and sampling.

Permits and Enforcement

Section 402 of the Federal Water Pollution Control Act Amendments of
1972  (6), "...creates a National Pollutant Discharge. Elimination System
under which the. Administrator o& the. Environmental Protection Age.nc.ij
mag, a^ter opportunity fior public hearings, issue, permute &or the. dis-
charge. o£ any pollutant on. combination oft pollutants, upon condition
that such discharge, will me.e£ all applicable. Jie.qulsiwe.ntf> o& the. Act
relating to e.^luent limitation*, water quatlty standards and imple.-
mewtation plant,, new source, performance, standards, i.nspe.ction, moni-
toring and entry provisions, and guideline* establishing ocean
discharge, csiit&ftia."

The Act requires that the Administrator of the USEPA prepare, and make
public, a fact sheet for every permit application having a total dis-
charge volume of more than 500,000  gallons on any day of the year.
 (The Administrator may prepare fact sheets for smaller discharges.)
Included in the fact sheet must be:   "A quantitative, description 0&
the. discharge. describe.d in the. NPPES application which tncludes^ the,
rate,  or £ke.quency ofi .tke. propose.d discharge.; 
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TYPES OF FLOW DATA REQUIRED

Basic flow data can be classified in accordance with their probable
accuracy, time continuity or discontinuity, and their general quantity
level - such as high, medium, or low.  All flow data must be synchro-
nized with time, at least on a watch time basis, to have any useful
meaning.  For some purposes, such as certain research or operation
functions, very precise time synchronization is necessary.  To in-
crease their usefulness, various statistical parameters such-as totals,
means, extremes, variability, and frequency are derived by analysis of
the basic flow data.

Continuous records of flow for the time period of interest probably
are most commonly required.  For planning and design of pollution con-
trol facilities, or for determining the effects of pollution on the
receiving stream, many years of continuous record of flow may be use-
ful.  Continuous "real-time" data for operation of facilities may be
needed for an indefinite time period.

In many storm sewers, flow outside the periods of storm runoff is
negligible.  Therefore, the need is for continuous record of flow
during periods of storm runoff only.  Flow measurement equipment can
be activated automatically by the onset of rainfall, or by preselected
water surface elevation, and can be deactivated in a similar manner.

There may be situations where the magnitude and frequency of peak flows
only would be required.  These data could, for example, be required for
determination of the maximum required size of sewers or other facilities.
In this case, crest-stage measurements only can be obtained by various
simple devices such as a vertical pipe stilling well with a graduated
rod left in it.  Maximum stage is recorded by a line of ground cork,
or other floatable material, left on the stick during a period of
storm runoff.  A calibrated primary device, such as a culvert, flume,
or rated channel, must be used with the crest-stage measuring equipment.

On the other hand, measurements of low flow only can be useful.  This
would be true in cases where low flow augmentation of the receiving
stream could be an acceptable measure for reducing the concentration
of pollutants in the stream.  Because of the usual slow change in
streamflow during periods of dry weather, comparatively few measure-
ments are needed to define such low flows.

Another type of flow measurement, often known as a miscellaneous meas-
urement, is made only at rather infrequent intervals of time.  The time
interval may ,be regular, or it may be simply at the convenience of the
hydrographer.  Such measurements are useful where flow is known to be
relatively steady.  Flows of effluent from treatment plants, effluent
                                   17

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from selected types of industrial plants, sanitary sewage, or storm
sewers during periods of dry weather may be satisfactorily defined by
miscellaneous measurements.

Often, flow measurements are made for the purpose of calibrating
another, possibly continuous type, flow measurement device.  For ex-
ample, a series of current meter measurements may be made over a range
of stages to calibrate a measuring flume which may not be precalibrated
satisfactorily.

The probable accuracy of flow data is determined by a number of factors.
Each type of flow measurement equipment has an inherent maximum capa-
bility for accuracy.  Care with which certain types of equipment are
installed affects the accuracy of the flow data.  Conditions under which
the equipment is used influence  the accuracy of the data collected.
The harsh conditions found in many sewers can be detrimental to meas-
uring equipment, and makes the work of the hydrographer difficult.  Use
of certain types of equipment necessitates considerable training and
experience if accurate records are to result.  Estimates of probable
accuracy of the data should always be furnished by field personnel as
a guide to the user, who otherwise has little means of knowing if they
should be rated as excellent, good, fair, or poor.
                                  18

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                            SECTION  IV

                   THE TIME  ELEMENT  IN FLOW DATA
Measurements of flow are useful only with respect to the relationship
of  the measured flow with other phenomena.  An assignment of time of
occurrence  to flow data makes possible a determination of its relation-
ship  to  other parameters whose times of occurrence are known.  The
other parameters of interest may or may not be synchronous with the flow
data.  In some cases, definition of the time interval between events is
sufficient  but, generally, the true clock time, preferably standard time,
of  the concerned flow is required.

IMPORTANCE  OF THE TIME ELEMENT

The required accuracy of the time element in flow data is very different
from  requirement to requirement.  An example is the use of peak flows
for each year to determine their frequency.  On the other hand, flows
at  intervals as short as one minute have been collected to define the
discharge hydrograph from small urban areas.

A particular need for improved accuracy in the time element occurs in
the measurement of flows from small urban storm sewers in order to de-
fine  the hydrograph and to provide data for development and verifica-
tion  of rainfall-runoff-quality models.  Accurate definition of both
the time and discharge elements of the hydrograph makes possible the
computation of total volume of runoff during the storm by computing the
area  under  the hydrograph, exclusive of base flow.  By selecting a num-
ber of well defined hydrographs resulting from storms of similar rain-
fall  characteristics, a typical hydrograph for the basin can be defined.
When  the hydrograph is so adjusted that its runoff volume is 2.54 cm
(1.00 in.)  of rainfall excess, it is called a "unit hydrograph", and it
can be conveniently used to define hydrographs resulting from similar
rainfalls of any volume of rainfall excess.  Shape of the unit hydro-
graph is determined by accurate timing as well as by dischargef although
it  is independent of clock time.   The hydrograph as defined by clock
time and discharge is often used to route flows along a stream channel
or  through  a reservoir.

Peak flows, storm runoff volumes, daily flows, or other flow parameters
are often correlated with similar flows at other points on a storm sewer
or  stream,  or with flows of other storm sewers or streams, to provide a
means for flow estimation.  Also, correlations may be made with various
physical characteristics of a basin, such as area, slope,  population
density, etc.  Correlations with temperature, soil moisture, or ante-
cedent precipitation may be made at times.   In most cases, it is
                                    19

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essential that the correlated variables be synchronous,  so  accurate
timing of the data is often required.

Timing of measured flows and collection of quality samples  can be use-
ful in determining sources of pollution.  For example,  they can  be
related to time of release of pollutants from industrial plants, or
to the time of accidental spills of pollutants.   The time of travel  of
pollutants along a stream or storm sewer can be  estimated from the time
of travel of small rises or other flow changes in the channel.

In many situations where flow measurement is used for operation  of pol-
lution control facilities, accurate timing of the flows  may be required.
This is particularly true where upstream flow data are transmitted
electronically for automatic control of gates, pumps, and other  devices
for the relief of stormwater flows.

CONTINUOUS RECORDING OF FLOWS

Many different kinds of equipment are available  for the continuous
recording of flow data.  In general, they consist of a clock, or timer,
which drives or regulates the rate of motion of  a strip chart or tape,
or a circular chart.  Discharge may be recorded  directly on the  chart
by pen, pencil, or digital punch; or, stage only may be recorded for
later conversion to discharge by means of known relationships of stage
to discharge.  This conversion may be made manually, with the aid of a
discharge integrator, or by means of a computer where digital punched
tape is available.

Adjustments, or corrections, to the record are usually required.  The
clocks or timers in general use do not maintain fully accurate chart
time.  Sliding time corrections are made for the periods between visits
when the chart position of the pen is compared with watch time of the
hydrographer.  Small errors in discharge or stage are similarly cor-
rected for the periods between visits.  Careful review of the charts
may reveal periods of clock stoppage, temporary backwater conditions,
or instrument malfunctions for which corrections may be made.

When the relationship between stage and discharge is nonlinear,  rapidly
changing stages must be subdivided into relatively short periods before
converting to discharge.  Due to intermittent use of daylight saving
time, and' inconsistent use of such time from place to place, all flow
records should be adjusted to standard time.

Clock Drives and Timers

Clock drives commonly used on flow recorders include spring wound,
suspended weight, battery powered motor, and synchronous motor  (alter-
nating current).  Except for those driven by synchronous motor through
                                  20

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 a power system of  regulated frequency,  significant  time  errors can be
 expected.   Errors  of  one or two  hours per week  are  common with recorders
 of the 8-day type.  Without careful  clock adjustment,  errors of several
 hours per  month in continuous-type recorders are  to be expected.  Timers
 on the digital paper  punches now widely used in the field by the U.S.
 Geological Survey  are said to provide correct timing within about
 15 minutes per month.  Where required,  more accurate timers are avail-
 able to substitute for those in  more general use.   Extremely accurate
 time can be maintained with quartz crystal  timers,  for example.  The
 cost of such solid state timers  is not  high, except for  those having
 refinements such as compensation for error  due  to temperature change.

 Synchronous data recording is often  achieved by the tracing of more
 than one data parameter  on a single  chart controlled by  a single timer.
 Thus, flow data may be traced together  with rainfall data to provide a
 better relationship between rainfall and runoff.  On one existing
 project, flow data from  several  sites are being transmitted to a central
 location and traced on a single  chart.  Although  the data thus recorded
 are synchronous, they are not necessarily plotted to correct clock time.
 In several systems  of combined sewers,  "real-time"  rainfall, quality,
 and flow data are  transmitted to a central  computer, which analyzes the
 data to provide control  of gates,  pumps, and regulators  for optimum sys-
 tem operation.

 Recorder Charts and Tapes

 Difficulty in recording  the correct  time.of flow  data  arises not only
 from error of timers,  but also from  mechanical  inaccuracies in the
 recorders, and from nonconstant  dimensions  of the recorder paper.
 Under moist, humid  conditions, most  paper charts  expand  a significant
 amount. Expansion of more than  0.5  percent is  to be expected at times.
 Error due  to expansion of a strip  chart could thus  be  one hour (or more)
 in 10 days of operation.   A recorder with an auxiliary pen that marks
 the paper  at uniform  intervals of  clock time, rather than relying upon
 preprinted time divisions on the chart, serves  as a basis for correction
 due to humidity effects.

 Timing of  digital  paper  tape punch recorders is not affected by changes
 in the paper tape  length because the punches occur  at  uniform intervals
.of clock time.

 NONCONTINUOUS FLOW DATA

 Other flow measurements,  such as the miscellaneous  type, are usually
 made directly by the  hydrographer  and are timed by  his watch.  It is
 important  that he maintain his watch as accurately  as  possible, and
 that he note the time as standard  or daylight saving,  whichever it
 may be.
                                   21

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It is neither possible, nor necessary, to determine the precise time
for crest~stage measurements of peak flows obtained as described above.
Usually, the time can be established closely enough for the purpose by
comparison with the corresponding peak stage at a nearby flow recording
site.
                                   22

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                            SECTION V

               DESIRABLE EQUIPMENT CHARACTERISTICS
From the brief review of the severe conditions and vagaries of storm
and combined sewer flow and discussions given in the preceding sections,
it is intuitively obvious that a number of very stringent design re-
quirements must be placed on flow measurement devices if they are to
function satisfactorily in such an application.  It should also be ap-
parent that no single design can be considered ideal for all flow meas-
urement activities in all storm and combined sewer flows of interest.
Characteristics of the available sites, as well as the particular flows
in question, make a device that might be acceptable for one location
totally unsuitable for another.  Despite this, one can set forth some
equipment "requirements" in the form of primary design goals and some
desirable equipment features in the form of secondary design goals.

PRIMARY DESIGN GOALS

The following are considered to be primary design goals for equipment
that is to be used to measure storm and combined sewer flows:

Range - Since flow velocities may range from 0.03 to 9 meters per second
(0.1 to 30 fps), it is desirable that the unit have either a very wide
range of operation; be able to automatically shift scales; or otherwise
cover at least a 100 to 1 range.

Accuracy - For most purposes, an accuracy of ±10% of the reading at the
readout point is necessary, and there will be many applications where
an accuracy of ±5% is highly desirable.  Repeatability of better than
±2% is desired in almost all instances.

Flow Effects on Accuracy - The unit should be capable of maintaining its
accuracy when exposed to rapid changes in flow;  e.g.,  depth" and velocity
changes in an open channel flow situation.  There are instances where
the flows of interest may accelerate from minimum to maximum in as short
a time period as five minutes.

Gravity and Pressurized Flow Operation - Because of the conditions that
exist at many measuring sites,  it is very desirable that the unit have
the capability (within a closed conduit) of measuring over the full
range of open channel flow as well as with the conduit flowing full and
under pressure.

Sensitivity to Submergence or Backwater Effects  - Because of the pos-
sibility of changes in flow resistance downstream of the measuring site
                                   23

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due to blockages, rising river stages including possible reverse flow,
etc., it is highly advantageous that the unit be able to continue to
function under such conditions or, at a minimum, be able to sense the
existence of such conditions which would lead to erroneous readings.

Effect of Solids Movement - The unit should not be seriously affected
by the movement of solids such as sand, gravel, debris,  etc. within
the fluid flow.

Flow Obstruction - The unit should be as nonintrusive as possible to
avoid obstruction or other interference with the flow which could lead
to flow blockage or physical damage to some portion of the device.

Head Loss - To be usable at a maximum number of measurement sites, the
unit should induce as little head loss as possible.

Manhole Operation - To allow maximum flexibility in utilization, the
unit should have the capability of being installed in confined and
moisture-laden spaces such as sewer manholes.

Power Requirements - The unit should require minimum power at the meas-
uring site to operate; the ability to operate on batteries is a definite
asset for many installations.

SECONDARY DESIGN GOALS

The following are desirable features for flow measuring equipment,
especially for use in a storm or  combined sewer application:

Site Requirements - Unit design should be such as to minimize site re-
quirements, such as the need for  a fresh water supply, a vertical drop,
excessive physical space, etc.

Installation Restrictions or Limitations - The unit should impose a
minimum of restrictions or limitations on its installation and be
capable of use on or within sewers of varying size.

Simplicity and Reliability - To maximize reliability of results and
operation, the design of the* unit should be as simple as possible, with
a minimum of moving parts, etc.

Unattended Operation - For the majority of applications, it  is highly
desirable that the equipment be capable of unattended operation.

Maintenance Requirements - The design  of the  equipment  should be  such
that  routine maintenance is minimal  and troubleshooting and  repair  can
be  effected with relative  ease, even in the field.
                                   24

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 Adverse Ambient Effects - The unit should be unaffected by  adverse
 ambient conditions such as high humidity, freezing  temperatures, hydro-
 gen sulphide or corrosive gases, etc.

 Submersion Proof - The unit should be  capable of withstanding  total
 immersion without significant damage.

 Ruggedness - The unit  should be of rugged construction  and  as  vandal
 and theft proof as possible.

 Self Contained  - The unit should be self  contained  insofar  as  possible
 in view of the  physical principles involved.

 Precalibration  - In order to  maximize  the flexibility of using the
 equipment in different settings it is  desirable that it be  capable of
 precalibration;  i.e.,  it should not be necessary to calibrate  the sys-
 tem at  each location and for  each application.

 Ease of Calibration -  Calibration of the  unit  should be a simple,
 straightforward  process  requiring a minimum amount of time  and
 ancillary equipment.

 Maintenance of  Calibration -  The unit  should operate accurately for
 extended periods  of time without requiring recalibration.

 Adaptability - The system should be capable of:  indicating and
 recording instantaneous  flow rates  and totalized flows; providing flow
 signals  to  associated  equipment  (e.g., an automatic sampler); imple-
 mentation of remote sensing techniques or incorporation into a com-
 puterized urban data system, including a multisensor single readout
 capability.

 Cost - The  unit should be affordable both in terms of acquisition and
 installation costs  as well as operating costs, including repair and
maintenance.

EVALUATION PARAMETERS

It iSj of course, not necessary that all of the primary and secondary
design goals be achieved for all flow measurement  requirements.  For
example, "spot" measurements of all flow rather than continuous records
are sufficient at times.  Flow measurement devices used to  calibrate
others need not necessarily be self contained, nor would unattended
operations be required.  Furthermore,  meeting all  of the listed design
goals for all installations and settings would be  difficult, if not
impossible, to achieve in a single design.
                                  25

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Nonetheless, the primary and secondary design goals can be used to
formulate a set of evaluation parameters against which a given design
or piece of equipment can be judged.  Since application details may
make certain parameters more or less important in one instance or
another, no attempt has been made to apply weighting factors or assign
numerical rank.  It is hoped that the evaluation factors will prove
useful, as a check list among other things, for the potential user
who has a flow measurement requirement and who may require assistance
in the selection of his equipment.

The evaluation parameters, together with qualitative scales, are presented
in the form of a flow measurement equipment checklist in Table 1.
                                    26

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               TABLE 1.   FLOW MEASUREMENT EQUIPMENT CHECKLIST
 Designation:
Evaluation Parameter
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
Range
Accuracy
Flow Effects on Accuracy
Gravity & Pressurized Flow
Operation
Submergence or' Backwater
Effects
Effect of Solids Movement
Flow Obstruction
Head Loss
Manhole Operation
Power Requirements
Site Requirements
Installation Restrictions
or Limitations
Simplicity and Reliability
Unattended Operation
Maintenance Requirements
Advers'e Ambient Effects
Submersion Proof
Ruggedness
Self Contained
Precal ibration
Ease of Calibration
Maintenance of Calibration
Adaptability
Cost
Portability
Scale
D Poor D Fair DGood
D Poor D Fair Q Good
DHigh D Moderate D Slight
D No D Yes
.D High D Moderate D Low
DHigh Q Moderate D Slight
QHigh D Moderate D Slight
.DHigh D Medium D Low
D P.oor D Fair D Good
DHigh D Medium D Low
DHigh .D Moderate D Slight
DHigh D Moderate D Slight
D Poor D Fair D Good
D No D Yes
DHigh D Medium D Low
DHigh D Moderate D Slight
D No D Yes
O Poor D Fair D Good
D No D Yes
D No D Yes
D Poor D Fair D Good
D Poor D Fair D Good
D Poor D Fair DGood
D High D Medium D Low
D No . D Yes
Weight and Score

























Comments:
                                      .27

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                           SECTION VI

                  METHODS OF FLOW DETERMINATION
GENERAL

This section is intended to provide the reader with an overview of the
physical principles that have been utilized in the design of equipment
for the quantitative measurement of flows.  It presents a discussion,
in generic terms, that may help the reader to better follow the treat-
ment of commercially available equipment given in Section VII.  There
are a number of excellent references on the subject and the reader is
referred to them for a more in-depth presentation.  Noteworthy among
these are the ASME monograph on fluid meters (7) which was used as a
guide for the organization of this section as well as much of its Con-
tent, Replogle (8) and McMahon (9) which were also liberally used as
resource material; the USDI Bureau of Reclamation's water measurement
manual (10), the Leupold and Stevens water resources data book (11),
and the many standard texts on hydraulics, fluid mechanics, etc.

Any flow measurement system can be considered to consist of two dis-
tinct parts, each of which has a separate function to perform.  The
first, or primary element, is that part of the system which is in con-
tact with the fluid, resulting in some type of interaction.  The sec-
ondary element is that part of the system which translates this
interaction into the desired readout or recording.  While there is al-
most an endless variety of secondary elements, primary elements are
related to a more limited number of physical principles, being depend-
ent upon some property of the fluid other than, or in addition to, its
volume or mass such as kinetic energy, inertia, specific heat, or the
like.  Thus the primary elements, or rather their physical principles,
form a natural classification system for flow measuring devices and
are so used in this discussion.

Flow measurement systems may be thought of as belonging to one of two
rather broad divisions, quantity and rate.  In quantity meters, the
primary element measures isolated  (i.e., separately counted) quanti-
ties of fluid either in terms of mass or volume.  Usually a container
or cavity of known capacity is alternately filled and emptied, per-
mitting an essentially continuous flow of the metered supply.  The
secondary element counts the number of these quantities and indicates
or records them, often against time.  In rate meters, by contrast, the
fluid passes in a continuous, uninterrupted stream, which interacts
with the primary element in a certain way, the interaction being depend-
ent upon one or more physical properties of the fluid.  In the  second-
ary element, the quantity of flow per unit time is derived from this
interaction by known physical laws supplemented by empirical relations.
A general categorization of flow meters by division, classification,

                                   28

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 type,  and sub-type is presented in Table 2.   Each classification is dis-
 cussed briefly in the following sub-sections.

 A slightly modified form of the flow measurement equipment  checklist
 given in Table 1 has been used to evaluate the various flow measuring
 devices and techniques in tabular form,  and  a matrix summary is  given
 at the end of this section.   It must be  re-emphasized that  these eval-
 uations are made with a storm or combined sewer flow measurement ap-
 plication in mind and will not necessarily be applicable for other
 types  of flows.   They are necessarily somewhat subjective,  and the
 writers apologize in advance to the clever reader who has made a partic-
 ular device work satisfactorily in such  an application and,  hence,
 feels  that it has been  treated unfairly.

 Only a few of the evaluation parameters  normally have numbers associated
 with them.   To assist the reader in interpreting the ratings, the fol-
 lowing general guidelines were used.   If the normal  range of a partic-
 ular device was  considered to be less than about 10:1,  it was termed
 poor;  if it was  considered to be greater than  around 100:1,  it was
 termed good.   The intermediate ranges were termed fair.   The accuracy
 that might reasonably by anticipated in  measuring storm or combined
 sewer  flows was  considered rather  than the best  accuracy achievable  by
 a  particular device.   For example,  although  a  sharp-crested weir may be
 capable of achieving accuracies of ±1.5%Nor  better in clear irrigation
 water  flows,  accuracies  of much better than  ±4-7% should not necessarily
 be anticipated for  a sharp-crested weir  measuring stormwater or com-
 bined  sewer discharges.   If  the accuracy of  a  particular flow measur-
 ing device or method was  considered to be  better  than around ±1-2%,  it
 was termed  good;  if it was considered  to be worse than around ±10%,  it
 was termed  poor.  The intermediate accuracies were termed fair.

 The flow measuring  devices and  techniques were not rated  on two evalua-
 tion parameters,  submersion  proof  and  adaptability, because these fac-
 tors are so  dependent upon the  design  details of  the secondary element
 selected by the user.

 SITE SELECTION

 The success  or failure of  selected  flow measurement equipment or methods,
with respect  to accuracy and completeness of data collected as well as
 reasonableness of cost, depends very much on the care and effort exe-
 cised in selecting  the gaging site.  Except for a few basic require-
ments which are applicable to all types of equipment and methods which
will be  discussed at this point, there are significant differences in
 site needs for various flow measurement devices.  Particular site re-
quirements will be addressed in the discussion of each equipment type.

A requirement which appears to be obvious, but which is frequently not
 sufficiently  considered, is that the site selected be located to give
the desired flow measurement.  Does flow at the site provide information
                                    29

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                TABLE  2.   FLOW METER CATEGORIZATION
DIVISION      CLASSIFICATION

QUANTITY   GRAVIMETRIC
QUANTITY   GRAVIMETRIC
QUANTITY   GRAVIMETRIC
QUANTITY   VOLUMETRIC
QUANTITY   VOLUMETRIC
QUANTITY   VOLUMETRIC
QUANTITY   VOLUMETRIC
QUANTITY   VOLUMETRIC
QUANTITY   VOLUMETRIC
QUANTITY   VOLUMETRIC
QUANTITY   VOLUMETRIC
RATE       DIFFERENTIAL PRESSURE
RATE       DIFFERENTIAL PRESSURE
RATE       DIFFERENTIAL PRESSURE
RATE       DIFFERENTIAL PRESSURE
RATE       DIFFERENTIAL PRESSURE
RATE       DIFFERENTIAL PRESSURE
RATE       DIFFERENTIAL PRESSURE
RATE       DIFFERENTIAL PRESSURE
RATE       DIFFERENTIAL PRESSURE
RATE       DIFFERENTIAL PRESSURE
RATE       DIFFERENTIAL PRESSURE
RATE       DIFFERENTIAL PRESSURE
RATE       DIFFERENTIAL PRESSURE
RATE       DIFFERENTIAL PRESSURE
RATE       DIFFERENTIAL PRESSURE
RATE       DIFFERENTIAL PRESSURE
RATE       VARIABLE  AREA
RATE       VARIABLE  AREA
RATE       VARIABLE  AREA
RATE       HEAD-AREA
RATE       HEAD-AREA
RATE       HEAD-AREA
RATE       HEAD-AREA
RATE       HEAD-AREA
RATE       HEAD-AREA
RATE       HEAD-AREA
RATE       HEAD-AREA
RATE       HEAD-AREA
RATE       HEAD-AREA
RATE       HEAD-AREA
RATE       FLOW VELOCITY
 RATE        FLOW VELOCITY
 RATE        FLOW VELOCITY
 RATE        FLOW VELOCITY
 RATE        FLOW VELOCITY
 RATE        FLOW VELOCITY
 RATE        FLOW VELOCITY
 RATE        FLOW VELOCITY
 RATE        FORCE-DISPLACEMENT
 RATE        FORCE-DISPLACEMENT
 RATE        FORCE-DISPLACEMENT
 RATE        FORCE-DISPLACEMENT
 RATE        FORCE-DISPLACEMENT
 RATE        FORCE-MOMENTUM
 RATE        FORCE-MOMENTUM
 RATE        FORCE-MOMENTUM
 RATE        FORCE-MOMENTUM
 RATE       THERMAL
 RATE       THERMAL
 RATE       THERMAL
 RATE       OTHER
 RATE       OTHER
 RATE       OTHER
 RATE       OTHER
 RATE       OTHER
 RATE       OTHER
 RATE       OTHER
           TYPE

WEIGHER
TILTING TRAP
WEIGH DUMP
METERING TANK
RECIPROCATING PISTON
OSCILLATING OR RING PISTON
NUTATING DISC
SLIDING VANE
ROTATING VANE
GEAR OR LOBED IMPELLER
DETHRIDGE WHEEL
VENTURI
DALL TUBE
FLOW NOZZLE
ROUNDED EDGE ORIFICE
SQUARE EDGE ORIFICE
SQUARE EDGE ORIFICE
SQUARE EDGE ORIFICE
SQUARE EDGE ORIFICE
CENTRIFUGAL
CENTRIFUGAL
CENTRIFUGAL
IMPACT TUBE
IMPACT TUBE
LINEAR RESISTANCE
LINEAR RESISTANCE
LINEAR RESISTANCE
GATE
CONE AND  FLOAT
SLOTTED  CYLINDER AND  PISTON
WEIR
WEIR
FLUME
FLUME
FLUME
FLUME
FLUME
FLUME
FLUME
FLUME
OPEN  FLOW NOZZLE
FLOAT
 FLOAT
TRACER
VORTEX
VORTEX
TURBINE
 ROTATING ELEMENT
 ROTATING ELEMENT
 VANE
 HYDROMETRIC PENDULUM
 TARGET
 JET DEFLECTION
 BALL AND TUBE
 AXIAL FLOW MASS
 RADIAL MASS
 GYROSCOPIC
 MANGUS EFFECT
 HOT TIP
 COLD TIP
 BOUNDARY LAYER
 ELECTROMAGNETIC
 ACOUSTIC
 DOPPLER
 OPTICAL
 DILUTION
 ELECTROSTATIC
 NUCLEAR  RESONANCE
                                                                         SUBTYPE
CONCENTRIC
ECCENTRIC
SEGMENTED
GATE OR VARIABLE AREA
ELBOW OR LONG RADIUS  BEND
TURBINE SCROLL CASE
GUIDE VANE SPEED RING
PITOT-STATIC
PITOT VENTURI
PIPE SECTION
CAPILLARY TUBE
POROUS PLUG
SHARP CRESTED
BROAD CRESTED
VENTURI
PARSHALL
PALMER-BOWLUS
DISKIN DEVICE
CUTTHROAT
SAN DIMAS
TRAPEZOIDAL
TYPE HS, H, AND HL

SIMPLE
INTEGRATING

VORTEX-VELOCITY
EDDY-SHEDDING

HORIZONTAL AXIS
VERTICAL AXIS
                                            30

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 actually needed to fulfill project needs?  Sometimes influent flows
 diversions, or storage upstream or downstream from the selected site
 would bias the data in a manner not understood without a thorough study
 of the proposed site.  Such study would include reference to surface
 maps and to sewerage maps and plans.  Sometimes groundwater infiltra-
 tion or unrecorded connections may exist.  For these reasons, a thorough
 field investigation should be made before establishing 'a flow measure-
 ment site.                  .

 There are some situations where there is no choice of sites.  Only a
 single site may be available where the desired flow measurement can be
 made.  In this case, the problem is one of selecting the most suitable
 flow measurement equipment and methods for the available site.

 A basic consideration in site selection is the possible availability of
 flow measurements  or records collected by others.   At times, data being
 collected by the U.S.  Geological Survey,  by the State,  or by other pub-
 Ixc agencies can be used.   There are locations where useful data,  al-
 though not currently being collected,  may have been collected in prior
 years.   Additional data to supplement  those earlier records may be more
 useful than new data collected at  a different  site.   Other general site
 considerations include any history of  surcharging,  entry  and backwater
 conditions,  and intrusion  from receiving waters.

 Requirements which apply to  all flow measurement sites are  accessibil-
 ity,  personnel and equipment  safety, and freedom from vandalism.   If  a
 car or  other vehicle can be  driven directly to the  site at  all  times
 the cost in  time required  for  installation, operation, and maintenance
 of the  equipment will  be less,  and  it  is possible that less  expensive
 equipment can  be selected.   Consideration  should be given to access
 during periods of  adverse weather  conditions and during periods of
 flood stage.   Sites on bridges  or at manholes where heavy traffic oc-
 curs  should be avoided unless suitable protection for men and equipment
 is provided.   If entry to sewers is required, the more shallow locations
 should be selected where possible.  Manhole steps and other facilities
 for sewer access must be carefully inspected, and any needed repairs
 made.  Possible danger from harmful gases, chemicals, or explosion
 should be investigated.  With respect to sites at or near streams, his-
 torical flood marks should be determined and used for placement of ac-
 cess facilities and measurement equipment above flood level where this
 is possible.  Areas of known frequent vandalism should be avoided.

 Selection of sites  in open, rather than secluded,  areas may help to re-
duce vandalism.  Often, the only solution to prevent destruction of fa-
cilities is to place them in solid concrete or steel shelters, and to
surround them with  heavy fencing.  Erection of warning signs is  futile,
as they often serve only to provide targets.
                                   31

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In development of a system or network of flow measurement stations,
primary consideration must be given to cost if the maximum benefit is
to result from available funds.  Therefore, cost must be considered in
selection of each gaging site., Cost reduction can result from selec-
tion of sites where the less expensive types of equipment, which will
fulfill project requirements of accuracy and completeness, can be in-
stalled.  For example, if a site is selected where conditions are such
that satisfactory records can be obtained with a weir installation,
this would be preferable to selecting a site where the head loss re-
quired by a weir would not be available, and the expense of installing
a Parshall flume must be met.

GRAVIMETRIC

As indicated in Table 2, gravimetric meters include weighers, tilting
trap and weigh dump meters.  Weighing the  fluid is a primary standard
and, since the accuracy of weighing devices is routinely considered to
be better than ±0.1%, they are frequently  used to calibrate other me-
ters as, for example, at the new National  Bureau of Standards flowmeter
calibration facility.  In its simplest  form, a gravimetric meter in-
volves determining the weight  of a quantity of fluid in a tank mounted
on beam scales, load  cells, or some other  mass or force measuring de-
vice.  Where flow is  uniform,  an indication of flow rate can be obtained
by measuring the time over which the measured weight of fluid is gath-
ered.  The tipping bucket rain gage is  probably one of the most common
meters of this type in field  use.  Another field application, used
where a scale or some other weighing device is available, is the sim-
ple  "bucket and  stopwatch" technique.   Practical considerations limit
the  use of this  technique to  fairly low flow rates, however.  Gravi-
metric meters may often have  a useful range of up  to  100:1,  and accu-
racies of ±1% of the  reading  or better  are routine.

All  types of  gravimetric meters as  a  class are  evaluated in  Table 3.
Since  they are  generally not  well  suited for  storm or combined  sewer
flow measurement, no  further  discussion will  be given.

VOLUMETRIC

Whenever the fluid density can be assumed to  be reasonably constant,  a
volumetric measure of flow is adequate.  Because of  their simplicity
 and lower "cost as compared to gravimetric meters,  most quantity meters
 found on the market today are volumetric devices.  A representative,
 but not inclusive,  listing of types of volumetric meters is given in
 Table 2.  As with gravimetric devices,  rates of flow can be indicated
 with many volumetric meters by using appropriate secondary elements.

 Probably the most elementary type of volumetric device is the metering
 tank.   An open tank is repeatedly filled  to a fixed depth and emptied.
                                    32.

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         TABLE 3.  GRAVIMETRIC METER EVALUATION (ALL TYPES)
        Evaluation Parameter
                                        Seal e
 6
 7
 8
 9
10
11
12

13
14
15
16
17
18
19
20
21
22
23
24
25
 Range
 Accuracy
 Flow Effects  on  Accuracy
 Gravity &  Pressurized  Flov\
 Operation
 Submergence or Backwater
 Effects
 Effect of  Solids  Movement
 Flow Obstruction
 Head Loss
 Manhole Operation
 Power Requirements
 Site Requirements
 Installation  Restrictions
 or Limitations
 Simplicity and Reliability
 Unattended Operation
 Maintenance Requirements
 Adverse Ambient Effects
 Submersion Proof
 Ruggedness
 Self Contained
 Precalibration
 Ease of Calibration
Maintenance of Calibration
Adaptabi1ity
Cost
Portability
 D Poor   D Fair     E3 Good
 D Poor   n Fair     £3 Good
 S High   D Moderate D Slight
 D No                & yes

 D High   D Moderate g] LOW

 K High   D Moderate D Slight
 KjHigh   D Moderate D Slight
 IE High   Q Medium   Q Low
 OS Poor   D Fair     D Good
 O High   C3 Medium   D Low
 §8 High   D Moderate D Slight
 13 High   D Moderate D Slight

 SI Poor   D Fair     D Good
 D No                 63 Yes
 53 High   D Medium   D Low
 DHigh   E3 Moderate D SIight
 D No                 Q Yes
 D Poor   53 Fair     D Good
 P No                 G3 Yes
 D No                 SI Yes
 D Poor   D Fair     63 Good
D Poor   SI Fair     D Good
D Poor   D Fair     Q Good
81 High    O Medium   D Low
8! No                 D Yes
                            33

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Although potentially not as accurate as weighing, since both the fluid
and tank are subject to temperature effects, accuracies of about ±1% of
reading are routinely achieved.  The usable range of a metering tank
device is a function of its design, but 10:1 is commonly achieved.

There have been a few instances where existing structures have been
used as volumetric flow measuring devices for stormwater or combined
sewage.  For example, in at least one location wet wells have been
utilized in a "fill and draw" fashion in order to provide an indication
of flow.  The monitoring of pump operations at lift stations in general
has been used in a number of cases to obtain flow information.  Such
techniques rely upon the use of existing equipment and structures, how-
ever, and flow measurement was not their original purpose.  For this
reason, they must be considered as techniques of opportunity rather
than as candidates for flow measurement equipment per se; consequently,
they will not be included in the evaluation table.

Many of the flow measuring devices in the volumetric classification are
positive displacement meters.  Such units may be considered to be fluid
motors operating with a very high volumetric efficiency under a very
light load.  This load is made up of two parts; the internal load due
to friction within the primary element, and the external load imposed
by the secondary element or register.  As in all fluid motors, work
done against a load results in a pressure drop.  The main factors in-
fluencing  the magnitude of this pressure drop are the type of seal re-
quired, the power required to drive the register, the viscosity of the
liquid, and the rate of flow.

Various ingenious mechanical implementations of such meters include
such types as the reciprocating piston, oscillating or ring piston,
nutating disc, sliding and rotating vane, and gear or lobed impeller.
Several of these have seen application in water meter designs for resi-
dential and commercial use.  They are seldom found in large sizes and
are obviously poorly suited for measuring storm or combined sewer flows.
A special  adaptation of a vane type meter is the Dethridge Wheel.  These
devices are widely used in Australia and New Zealand to measure irriga-
tion water flows, but are almost unknown in the United States.  Accura-
cies of ±3.5% are reported for free discharge conditions  for  discharge
rates  between 0.042 and 0.14 cm/s  (1.5 and  5.0 cfs).  Maximum ranges of
5:1 have been achieved in smaller  sizes.

All  types  of volumetric meters as  a class are evaluated  in Table  4.
Since  they are  generally not well  suited for storm or  combined  sewer
flow measurement, no  further discussion will be  given.   Complete  de-
scriptions and  discussions  can be  found in  the references -  especially
ASME (7),  Replogle  (8), and McMahon  (9).
                                    34

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          TABLE 4.  VOLUMETRIC METER .EVALUATION (ALL TYPES)
        Evaluation Parameter
                                             Scale
  6
  7
  8
  9
 10
 11
 12

 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
25
 Range
 Accuracy
 Flow Effects on Accuracy
 Gravity & Pressurized Flow
 Operation
 Submergence or Backwater
 Effects
 Effect  of Solids  Movement
 Flow Obstruction
 Head Loss
 Manhole Operation
 Power Requirements
 Site Requirements
 Installation  Restrictions
 or Limitations
 Simplicity  and  Reliability
 Unattended  Operation
 Maintenance Requirements
 Adverse  Ambient Effects
 Submersion  Proof
 Ruggedness
 Self Contained
 Precalibration
 Ease of  Calibration
Maintenance of Calibration
Adaptabi1ity
Cost
Portability
 8 Poor   QFair     DGood
 D Poor   D Fair     K Good
 53 High   Q Moderate D Slight
 D No                63 Yes

 D High   D Moderate K LOW

 8 High   D Moderate D Slight
 63Hign   D Moderate D Slight
 DHigh   8 Medium   Q Low
 63 Poor   D Fair     D Good
 DHigh   D Medium   63 Low
 8 High   Q Moderate D Slight
 83 High   D Moderate D Slight

 D Poor   S! Fair     D Good
 D No                & Yes
 S3 High   D Medium   D Low
 D High   K Moderate Q Slight
 D No                D Yes
 D Poor   53 Fair     D Good
 D No                B Yes
 D No                |g Yes
 D Poor   D Fair     Bl Good
 D Poor   63 Fair     DGood
D Poor   D Fair     DGood
H High    D Medium   D Low
K No                .Q Yes
                             35

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DIFFERENTIAL PRESSURE

Flow measuring devices that fall in the differential pressure classifi-
cation operate by converting energy from one form to another.  For ex-
ample, in those primary devices that have a reduced cross-section,
potential energy is converted into kinetic energy to produce a differ-
ential pressure, while in the impact type devices the reverse is true.
Centrifugal type devices utilize the acceleration of the flow around a
bend, while linear resistance type devices are based on frictional
losses.  In many designs a combination of velocity head, frictional
losses, or stream-line bending is employed.  An important feature of
all flow measuring devices in the differential pressure classification
used here is  that they can only be used in a closed conduit  flowing full
and under pressure.

Venturi

As noted above, when  a fluid flows through a conduit of varying  cross-
section its velocity  varies from point  to point along  the conduit or
passage.  If  the velocity increases,  the passage  is called a nozzle,
and  the kinetic energy increases at  the expense of internal  energy.   If
the  velocity  decreases,  the passage  is  called  a diffuser, and  the in-
ternal energy increases  at the  expense  of kinetic energy.  If  the_cross-
section of  a  nozzle decreases continuously  from entrance  to  exit it  is
called converging,  and if it increases  continuously it is called di-
verging.  The cross-section of  a  diffuser may  either  increase  or de-
crease depending  on whether  the flow is supersonic  or subsonic.  A
venturi  is  a  converging  nozzle  followed by  a subsonic diffuser.  The
region of minimum cross-section is called the  throat.   A number of  dif-
 ferent venturi geometries have been developed  over  the years,  one of
 the more common being the standard (long-type) Herschel Venturi meter
 tube (Figure 3).

 The venturi meter is one of the most accurate devices for measuring
 liquid flow rates in pipes,  but it is not in common use for waste flow
 measurement for a number of reasons, not the least of which is its cost.
 The venturi causes a very low pressure loss and,  with proper precau-
 tions, is good for use in liquids with high solids concentrations.   For
 example, A!TM Standard D 2458 states (12) "(Wwn a vejfcifce. *abe * to be.
 txed to*, meters -fcuzuufc c-ontatning to*ae. concentfiattonA (^Apended
 &oLu& on AJLudQZ, the. annual >vinQ te e^inu.nate.d and ftep£aced by
 hole, tap* at tke. Met and throat and tke*e. vie. itu&kid
 VlJUtk CJLVW MOteJi."   It is further recommended that the flushing water
 pressure should exceed the maximum line pressure by at least 0.7 kgf/sq
 cm  (10 psi).  The flushing water flows should be equal and  continuous,
 and held to  a  small  quantity to prevent any measurable pressure differ-
 ential which would be reflected in  the metering instrument.
                                     36

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It is essential that the flow entering a venturi tube be of uniform
turbulence, free from helical flow and from high or low pressure areas.
Therefore, long uninterrupted runs of straight pipe upstream from the
venturi location are desirable .for accurate fluid metering.  Straighten-
ing vanes can often be used to reduce the upstream straight pipe run re-
quirement when the Sisturbing device produces spiral flows, but they do
little to reduce the effects of elbows and partly opened gate valves.
The required run depends upon the nature of the upstream element; e.g.,
elbow, gate and globe valve, decreaser, increaser, etc., and the ratio
of the throat diameter to the pipe diameter.  Typically, the minimum de-
sirable straight run will be from 5 to 20 pipe diameters.  Conditions
downstream from the venturi tube have little effect on its performance.

The pressure differential of a venturi tube can be measured using mer-
cury columns, electrically, pneumatically, or by incorporating a water
level sensing device  (e.g., a float operated instrument) and water col-
umns.  Although manufacturers typically supply rating curves with their
instruments, ASTM  (12) recommends that each venturi be calibrated in
place to meet accuracy standards.  Accuracy is affected by changes in
density,  temperature, pressure, viscosity, and by pulsating flow.  Under
ideal conditions a venturi  can yield accuracies of around  ±0.5/  of the
reading, but more  typical accuracies achieved are about ±1 or 24.  Most
installations are  usable over a range of  5:1 or so.  Venturi tube meters
are  evaluated in Table 5.

Flow Tubes

Following the development of  the  Herschel venturi  tube  in  1887,  a num-
ber  of variations  such as the short-coned venturi were  developed.  Among
 the  more recently  introduced  venturi-type primary  devices  is  the Dall
 flow tube (13), which was developed in England.   The Dall  tube  consists
 of a flanged cylindrical body designed with a short  straight  inlet  sec-
 tion which terminates abruptly with a decrease in diameter,  thus form-
 ing  a shoulder.   This is  followed by a conical reducer  and diverging
 outlet separated by a narrow throat.   In effect,  the Dall  tube  uses
 stream-line bending as well as velocity head to obtain a differential
 pressure larger than that produced by a standard venturi meter.   Single
 hole pressure taps are located at the inlet shoulder and the throat
 (Figure 4).  Both pressure taps  can be continuously flushed with clean
 water to prevent plugging from solids in the flow as done with the ven-
 turi tube.'

 The Dall tube is almost as accurate as the standard venturi and has a
 higher head recovery, being one of the lowest permanent head loss de-
 vices known.  It is more sensitive to system disturbances than the ven-
 turi, and straight upstream pipe runs of 40 pipe diameters or more may
 be required.  Although somewhat cheaper than the venturi, the Dall tube
 must still be considered expensive.  It is much shorter than either
                                    38

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TABLE 5.  VENTURI TUBE METER EVALUATION
Evaluation Parameter
1
2
3
4
5
6
7
8
9
10
11
12

13
14
15
16
17
18
19
20
21
22
23
24
25
Range
Accuracy
Flow Effects on Accuracy
Gravity & Pressurized Flow
Operation
Submergence or Backwater
Effects
Effect of Solids Movement
- Flow Obstruction
Head Loss
Manhole Operation
Power Requirements
Site Requirements
Installation Restrictions
or Limitations
S i rnp 1 i c i ty a nd Re 1 i ab i 1 i ty
Unattended Operation
Maintenance Requirements
Adverse Ambient Effects
Submersion Proof
Ruggedness
Self Contained
Precal ibration
Ease of Calibration
Maintenance -of Calibration
Adaptability
Cost
Portabi 1 i ty
Scale
E3 Poor
D Poor
D High
K No
D High
D High
D High
D High
53 Poor
D High
& High
K High

D Poor
D No
D High
D High
D No
D Poor
D No
D No
D Poor
D Poor
D Poor
BHigh
52 No
D Fair Q Good
D Fair S3 Good
D Moderate 83 Slight
D Yes!
D Moderate 6i Low
D Moderate K Slight
D Moderate Eg Slight
D Medium g| Low
D Fair D Good
D Medium S! Low
D Moderate D Slight
D Moderate D Slight

D Fair SJ Good
B Yes
S3 Medi urn D Low
53 Moderate n Slight
D Yes
D Fair |g Good
IS Yes
8 Yes
D Fai r 53 Good
D Fai r 53 Good
CH Fair Q Good
D Medium D Low
D Yes
                 39

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               Q_
               
-------
              1VG^U   tU^S'  and thus has less of an installation re-
              The throat of the Ball tube can foul, and it is not gener-
  in ?aWeT          extremely dirty fluids.   Dall tubes are evaluated


  There have also been a number of recent American proprietary develoo-
  atntne S?^:1 °f/hi,C\1S  the "L°-Loss" tube.   ll senses the vl±£
  a  curte ^r^^-     d ^ ^ CentrifuSal action of the  liquid  rounding
  a  curve and the impact pressure at the inlet.   It is also a high head
  recovery device but,  unlike the Dall  tube,  can generally be successfully

  ments VSS   ^  ^^   ™* *** excePtion>  the evaluation com- 7
  ments  of Table 6 can be assumed applicable  to  the "Lo-Loss"  tube also.

  The Gentile tube is  a somewhat  different venturi-type differential pres-
  sure producer,  in which there is  a slight constricSon in  tS line/
  Pressure ports  exist  in the wall  of the constriction.  These ports face
  in opposite  directions  and the  effect  is somewhat similar  to the

 nlifv^r^f P±t0t  tUbe<  In effeCt theSS Pit0t tubes are us*d to am-
 of fL nn^   ^ PfS!fUre;  Because of the type of construction and size
 ?L2J«P ? £     dev"e has limitations for the measurement of flow of
 liquids which carry solid matter in suspension.  It also suffers from
 an extremely limited range (less than half that of a Dall tube)   a
 greater sensitivity to upstream disturbances,  and less head recovery
 consequently, this device will not be discussed further.      ecovery»

 Flow Nozzle

 Various designs have been developed for flow nozzles, resulting  in
 characteristics that approach  those of a venturi tube in  one extreme
 (venturi insert nozzle) and  those of an orifice meter in  the  other fASME
 long radius nozzle).   More typically,  a flow nozzle has an entrance
 f£!fuslfr°S- aS  ^ * VentUr± tUb6'  bUt lacks the recovery cone
 A ™fSr^;f     session essentially affects  the head recovery only.
 A major difference  (and advantage over the venturi tube)  in installa-
 Son^VS £at ?    W n°Zzle °an be installed  in  pipe flanges (see Fig-
 ure 5).  Nozzles are  less  expensive than venturi tubes, but cost more
 than orifice meters.   In general they  are more  sensitive  to upstream
 disturbances and 20 or more pipe diameters of straight run  upstream of
 the flow nozzle are required for successful operation.  While some de-
 signs,  (e.g., ASME nozzle) are quite well suited  (with proper precau-
 tions)  for measuring  liquids high  in suspended solids,  other  (e.g.
venturi  insert nozzle)  are not recommended for use in  such  flows!  due
 to some  aspect of their  particular design that would tend to promote
plugging or clogging.  Flow nozzle accuracies can approach  those of
venturi  tubes, especially when calibrated in place.  It is also possi-
ble to use a flow nozzle in cases where a pipe (flowing full) discharges'
fSSl.   ^e atmosphere.  In such cases only the high pressure tap is
needed; see Figure 6.  Flow nozzles as a group  are evaluated in Table 7
                                  41

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              TABLE 6.  BALL TUBE METER EVALUATION
       Evaluation  Parameter
                                           Scale
 1   Range
 2   Accuracy
 3   Flow  Effects  on  Accuracy
 4   Gravity  &  Pressurized Flow
    Operati on
    Submergence or Backwater
    Effects
 6   Effect of  Solids Movement
 7  -Flow  Obstruction
 8   Head  Loss
 9   Manhole Operation
10   Power Requirements
11   Site Requirements
12   Installation Restrictions
    or Limitations
13   Simplicity and  Reliability
14  Unattended Operation
15  Maintenance  Requirements
16  Adverse Ambient Effects
17  Submersion Proof
 18  Ruggedness
 19  Self  Contained
 20  Precalibration
 21  Ease  of Calibration
 22  Maintenance  of  Calibration
 23  Adaptability
 24  Cost
 25  Portability
53 Poor   QFair     D Good
Q Poor   QFair     SI Good
D High   Q Moderate IS Slight
K No                D Yes

Q High   Q Moderate IS Low
D High
D High
DHigh
SI Poor
D High
Si High
D High

Q Poor
D No
D High
D High
D No
 D Poor
 D No
 D No
 Q Poor
 Q Poor
 Q Poor
 SI High
 SI No
Si Moderate Q Slight
D Moderate SI Slight
D Medium   SI Low
Q Fair     D Good
Q Medium   St Low
D Moderate D Slight
B) Moderate D Slight

Q Fair     Sj Good
           Si Yes
S! Medium   Q Low
K Moderate Q Slight
           D Yes
D Fair     K Good
           Si Yes
 D Fair
 SI Fai r
 D Fair
 Q Medi urn
SJ Good
D Good
Q Good
Q Low
D Yes
                              42

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TABLE 7.  FLOW NOZZLE METER EVALUATION
Evaluation Parameter
1
2
3
4

5

6
7
8
9
10
11
12

13
14
15
16
17
18
19
20
21
22
23
24
25
Range
Accuracy
Flow Effects on Accuracy
Gravity & Pressurized Flow
Operation
Submergence or Backwater
Effects
Effect of Solids Movement
-Flow Obstruction
Head Loss
Manhole Operation
Power Requirements
Site Requirements
Installation Restrictions
or Limitations
Simplicity and Reliability
Unattended Operation
Maintenance Requirements
Adverse Ambient Effects
Submersion Proof
Ruggedness
Self Contained
Precal ibration
Ease of Calibration
Maintenance -of Calibration
Adaptability
Cost
Portabi 1 i ty
Scale
£3 Poor
D Poor
D High
"H No

D High

D High
D High
D High
E9 Poor
D High
K High
D High

D Poor
D No
D High
D High
D No
D Poor
D No
D No
D Poor
D Poor
D Poor
D High
& No
D Fair DGood
D Fair gj Good
D Moderate 83 Slight
D Yes

D Moderate 53 Low

D Moderate & Slight
D Moderate C3 Slight
•"18 Medium D Low
D Fair D Good
Q Medi urn 53 Low
D Moderate D Slight
C3 Moderate D Slight

D Fair 53 Good
B Yes
D Medi urn S3 Low
63 Moderate Q Slight
D Yes
D Fair 53 Good
53 Yes
g Yes
D Fair E3 Good
D Fair SI Good
D Fair D Good
. C§) Medium D Low
D Yes
                 45

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Orifice Meters

The orifice meter is one of the oldest flow measuring devices in exist-
ence.  Its differential pressure is due to a combination of velocity
head, frictional losses, and stream-line bending (acceleration).  The
relative contribution is determined by whether pipe taps, vena contracta
taps, or flange taps are used.  The thin plate orifice meter is the most
commonly used flow measuring device in pipes.  The orifice is a round
hole in a thin flat plate that is clamped between a pair of flanges at
a point in the pipe.  Although some designs have a rounded edge facing
into the direction of the flow and perhaps a short tube with the same
inside diameter as the orifice diameter extending downstream, it is
more common to use a sharp 90-degree corner on the upstream edge.  The
pressure taps are located upstream and downstream of the orifice Plate.
An orifice plate can also be used at the end of a pipe flowing full and
discharging to atmosphere, in which case only a single pressure tap is
required.

Orifice meters work well with clean fluids but are not applicable, ex-
cept in a limited sense, to flows high in suspended solids due  to the
tendency of solids to accumulate upstream of the orifice plate  and
thereby change its calibration.  There are  two designs that will accom-
modate limited amounts  of  suspended solids.  The eccentric orifice
plate has a hole which  is bored off-center, usually tangent  to  the bot-
tom  of the flow line.   The segmental orifice plate has a segment removed
from the lower half of  the orifice plate.   In addition,  there are many
special-purpose devices that  are really  combinations of  flow nozzles
and  orifice plates.  These have arisen due  to requirements  to minimize
viscosity effects in heavy fluids, etc.

Orifice plates  are  the  most  sensitive of all the differential pressure
devices  to  effects  of upstream disturbances,  and it  is not uncommon to
need 40 to  60 pipe  diameters of  straight run upstream of the installa-
 tion.   Orifice  plates also produce the greatest head loss  as can be
 seen by the comparison  curves of Figure 7.   Orifice  meters can be  quite
 accurate, with ±0.5% or better achievable when calibrated in place.
 They are lowest in cost of all the differential pressure producers.   Be-
 cause of nonlinear flow effects,  their usable range  is small (on the
 order of 5:1) unless rated in place.   Orifice meters are evaluated as a
 group in Table 8.

 Centrifugal Meters

 Flow acceleration induced in a fluid going around a bend (such as an
 elbow) produces a differential pressure that can be used to indicate
 flow.  The pressure on the outside of an elbow is greater than on the
 inside, and pressure taps located mid-way around the bend (i-e., 45 de-
 grees from either flange) can be connected to a suitable secondary
                                     46

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PERMANENT HEAD LOSS
(PERCENT OF MEASURED DIFFERENTIAL)
— ' ro co .p. en cr> ^i oo UDC
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•URI

        .1   .2  .3   .4   .5.6-7.8  .9   1
                   DIAMETER RATIO
Figure  7.  Head Loss of Differential Pressure Meters
                     47

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TABLE 8.  ORIFICE METER EVALUATION
Evaluation Parameter
1
2
3
4

5

6
7
8
9
10
11
12

13
14
15
16
17
18
19
20
21
22
23
24
25
Range
Accuracy
Flow Effects on Accuracy
Gravity & Pressurized Flow
Operation
Submergence or Backwater
Effects
Effect of Solids Movement
Flow Obstruction
Head Loss
Manhole Operation
Power Requirements
Site Requirements
Installation Restrictions
or Limitations
Simplicity and Reliability
Unattended Operation
Maintenance Requirements
Adverse Ambient Effects
Submersion Proof
Ruggedness
Self Contained
Precal ibration
Ease of Calibration
Maintenance of Calibration
Adaptability
Cost
Portability
Scale
E3 Poor D Fair CD Good
n Poor 55 Fair D Good
D High D Moderate S3 Slight
B No D Yes

D High D Moderate 63 Low

81 High D Moderate D Slight
KJHigh D Moderate D Slight
K High D Medium D Low
53 Poor DFair D Good
D High D Medium 81 Low
S3 High D Moderate D Slight
D High D Moderate 53 Slight

D Poor D Fair SI Good
D No » Yes
81 High D Medium D Low
DHigh 8) Moderate Q SI i ght
D No D Yes
D Poor 81 Fair D Good
D No 81 Yes
D No 8! Yes
D Poor DFair Kl Good
SI Poor D Fair D Good
D Poor D Fair D Good
DHigh D Medium 81 Low
D No H Yes
                 48

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 element for indicating or recording.  Cortelyou (14), Taylor and
 McPherson (15), and Replogle, et. al. (16) provide fuller discussions
 of centrifugal meters.  The turbine scroll case and guide vane speed
 ring do not appear at all well suited for storm or combined sewer ap-
 plications,  and so will not be discussed.

 The elbow meter may have some application,,^ .existing pipe systems.   It
 should not be considered as a candidate for accurate flow measurement
 in new construction, however.  It is inexpensive,  offers no additional
 head loss, can tolerate solids, if the pressure taps are flushed (see
 venturi discussion), and is not especially subject to calibration
 shifts.  If  calibrated in place, accuracies of about ±1 or 2% (or bet-
 ter in some  cases) may be achieved.   More typically, accuracies of 3 to
 10% are encountered.  Unless calibrated in place,  straight pipe runs of
 at least 20  pipe diameters should be provided both upstream and down-
 stream of the elbow..  The usual rangeability is around 3:1.   Elbow me-
 ters are evaluated in Table 9.

 Impact Tube

 In the impact tube,  kinetic energy (due to fluid velocity)  is converted
 into potential energy (stagnation pressure)  and the differential pres-
 sure (as  compared with static pressure  in the pipe)  is related to flow
 velocity  at  the point of  measurement.  Figure 8 depicts the  two essen-
 tial ingredients and a particular construction known as the  Prandtl-
 Pitot tube.   Alternate designs  consist of essentially the  same two basic
 ingredients  (impact  tube  and  pressure tube)  and differ only  in the de-
 tails of  their  construction.  H.  Pitot's  original  design (1732)  had two
 tubes,  one of which  was bent  through 90 degrees  at  its  lower end and
 positioned facing into the  flow.  H. Darcy's  design  (1852) had each
 tube bent  through 90 degrees, with one facing upstream (impact)  and the
 other facing  downstream.  In  addition to  the  Prantdl  design  (with its
 hemispherical head)  which is  popular today, especially  in Europe,  is the
 Brabbe  design with a conical head, which  is popular in  the United States
 and United Kingdom.   In another design, two parallel  small-diameter
 tubes are beveled at  their open ends, one pointing upstream  (impact)
 and one pointing  downstream  (static).

 It must be emphasized that impact tubes measure point velocity only.
Flow  is calculated by multiplying the mean velocity of the fluid by the
area  of the pipe cross-section.  For pipes flowing full and under pres-
sure  it has been determined that the mean velocity of flow is about 83%
of the velocity in the center of the pipe and it occurs at a point ap-
proximately one-fourth the radius from the wall to the center.  Velocity
close to the pipe wall is only about one-half the velocity at the cen-
ter.  To avoid upset of such normal velocity distributions it is neces-
sary to have a straight pipe run of some 15 to 50 pipe diameters in
length upstream of the measuring point.   Alternately, velocity traverses
                                   49

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TABLE 9.  ELBOW METER EVALUATION
Evaluation Parameter
1
2
3
4

5

6
7
8
9
10
11
12

13
14
15
16
17
18
19
20
21
22
23
24
25
Range
Accuracy
Flow Effects on Accuracy
Gravity & Pressurized Flow
Operation
Submergence or Backwater
Effects
Effect of Solids Movement
Flow Obstruction
Head Loss
Manhole Operation
Power Requirements
Site .Requirements
Installation Restrictions
or Limitations
Simplicity and Reliability
Unattended Operation
Maintenance Requirements
Adverse Ambient Effects
Submersion Proof
Ruggedness
Self Contained
Precal ibration
Ease of Calibration
Maintenance of Calibration
Adaptabi 1 i ty
Cost
Portabi 1 ity
Scale
53 Poor DFair D Good
D Poor 53 Fair D Good
D High D Moderate 53 Slight
53 No D Yes

D High D Moderate 53 Low

D High D Moderate 53 Slight
fj High D Moderate 53 Slight
D High D Medium 53 Low
53 Poor D Fair D Good
D High D Medium 58 Low
53 High D Moderate D SI i ght
D High D Moderate 53 Slight

D Poor DFair 53 Good
D No SI Yes
D High D Medium gj Low
DHigh 53 Moderate D SI i ght
D No D Yes
D Poor D Fair 53 Good
D No 53 Yes
63 No D Yes
D Poor K Fair D Good
D Poor D Fair 53 Good
D Poor D Fair D Good
DHigh D Medium 53 Low
S3 No D Yes
                50

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           51

-------
can be run to determine the point of mean velocity.  Such an approach
also allows the pitot tube to be used in conduits of noncircular cross-
section and under open channel flow conditions.

With very high velocities dynamic instability may occur, and erroneous
readings result from the tube vibrations.  However, the chief disadvan-
tage of most pitot tube designs is that rather sophisticated secondary
devices are required to accurately determine the pressure differential
which may be quite small at low velocities, e.g., less than 0.3 m/s
(1 fps).  This makes continuous flushing secondary devices more diffi-
cult to employ and, to the writers' knowledge, no such attempt has yet
been made.

Therefore, impact tube type devices are generally not satisfactory for
measuring wastes containing appreciable quantities of suspended solids
because of the possibility of plugging of the small openings in the
tubes.  In view of this, the vulnerability to damage arising from their
intrusive nature, and the difficulties in applying them in open chan-
nel flows of varying depths, no further discussion will be given.

Linear Resistance

Linear resistance meters use friction losses to  create a differential
pressure that can be related to flow rate.  The  resistance of a long
pipe section may be used, but one  or more fine tubes in parallel  (cap-
illary tube) or a section of pipe  packed with steel wool, granular ma-
terials, or the like  (porous plug)  are more typical,  Fleming and
Binder  (17), Greef and Hackman  (18), and Severs  and Binder  (19) discuss
various approaches and designs.  Accuracies to 1%  of the reading and
ranges of  10:1 may be achieved.  There is no pressure recovery.  Be-
cause of the impracticality  of utilizing such  devices for measuring
storm or combined sewer  flows, they will not be  discussed further.

VARIABLE AREA

Whereas  differential pressure flow measuring  devices are  characterized
by the  invariability  of  the area  ratio,  in variable  area meters  the
magnitude  of  the varying cross-sectional area is the measure of  the
 rate of  flow.  A differential pressure does  exist, but  it is relatively
 constant.   Variable area flowmeters may be divided into two main groups,
valve  type (e.g., hinged or sliding gate)  and float  type (e.g.,  cone-
 and-float).  Variable area devices were invented by  E.  A. Chameroy,  who
 patented an instrument constituting a prototype of the rotameter in
 1868,  and G.  F.  Deacon,  who was given a patent for a cone-and-disc
 flowmeter in 1875.   Sir J.  A.  Ewing was the  first to apply  a tapered
 glass  tube in a liquid rotameter in 1876,  and in 1910 K.  Kupper intro-
 duced inclined slots on the upper rim of the float and first used the
 term rotameter for this type of device, because of the rotary motion of
                                    52

-------
 the float.  Discussions of such devices are given by Kehat (20) and
 Gilmont and Roccanova (21).  Accuracies to ±1% of full scale and ranges
 to 10:1 may be achieved.  However, to maintain accuracy in a rotameter
 it is absolutely essential that both the tube and the float be kept
 clean.  Thus, a storm or combined sewer application would be inappro-
 priate and, consequently, they will not be discussed further.

 HEAD - AREA

 Flow measurement devices in this classification are characterized by a
 simultaneous variation of both flow cross-sectional area and head.
 These parameters do not vary indpendently,  however, and it is the func-
 tion of the primary device to produce a flow that is characterized by a
 known relationship (usually nonlinear)  between a liquid level measure-
 ment (head) at some location and the overall discharge.  This relation-
 ship or head-discharge curve is called  the  rating for the particular
 structure  or device.   Since these devices implicitly require a free
 surface, they are only suitable for open channel flows.

 The change in elevation of the free surface is measured by the secondary
 device which may also  convert stage to  discharge automatically.   Still-
 ing wells  are often used,  being connected by suitable taps to the loca-
 tion in the primary device where knowledge  of the flow depth  is  desired.
 The secondary device then monitors the  relatively stable surface level
 of  the fluid in the stilling  well.   To  avoid the necessity of frequent
 cleaning of the stilling well and to  help prevent plugging of the tap,
 fresh water is frequently  trickled into the well at  a rate sufficient
 to  ensure  that sewage  isn't likely to enter.   An overpressure of at
 least  0.003 meter  (0.01  ft) is  usually  required to keep the well and tap
 clear,  but  in some  cases greater  cleaning flows  along with frequent
 flushing will be necessary.

 Slope-Area Method

 In  this technique,  the flow conduit itself  serves as  the primary device.
 Historically,  it has been used  to obtain instantaneous discharges rather
 than continuous records.  Some discharge relationship such as the
Manning•formula is used to relate depth to  flow rate.  For best results,
a straight course of channel of at least 61 meters (200 ft) and prefer-
 ably up to 305 meters  (1000 ft) in length is required.  It should be
nearly uniform in slope, cross-section, and roughness and free of rap-
ids, abrupt falls (dips), sudden contractions or expansions, and tribu-
 tary inflows.

The Manning formula requires knowledge of the channel cross-section and
liquid depth so that the flow cross-section and hydraulic radius can be
calculated.  It also requires knowledge of  the slope of the water sur-
face (not the conduit invert).  This slope may be determined by dividing
                                   53

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the difference in the water surface elevations at the two ends of the
course, as determined by secondary devices carefully referenced to a
common datum level, by the length of the course.  Also required in the
Maiming formula is a roughness factor which depends upon the character
of the conduit lining and the depth of flow (i.e., it is not constant
for a given channel).  Because the proper selection of the roughness
factor is at best an estimate, the discharge determined by the slope-
area method is only an approximation, and it should be used only where
accuracy requirements are low.

All too often, the slope-area method is applied by measuring the flow
depth at a single point and using the slope of the conduit invert in
the Manning formula.  For nonuniform or unsteady flow, the water sur-
face slope will be changing and will certainly not be equal to the
channel slope.  The Manning formula was not intended for use under such
conditions.  It is preferable to perform calibration in place and de-
velop an empirical rating curve for each measuring site.  The slope-
area method is evaluated in Table 10.

Weirs

A weir is essentially an overflow structure or dam built across  the
flow conduit to measure the rate of flow.  For a weir of a given size
and shape with free-flow, steady-state conditions and proper weir-to-
pool relationships, only one depth of liquid  can exist in the upstream
pool for a given discharge.  Discharge rates  are computed by measuring
the vertical distance from the crest of the overflow part of the weir
to the water surface in the pool upstream of  the crest and referring to
the rating curve for the particular weir or class of weirs at hand.
Thus, a weir may be thought of as a device for  shaping the flow  of  the
liquid in a definite way such as to allow a single depth reading to be
uniquely related to a discharge rate.  Weirs  may be further categorized
as being either sharp-crested or broad-crested; each will be discussed
in  turn.

Sharp-Crested Weirs  - When  the  top  edge of the  weir is thin or beveled
with a sharp upstream corner  (similar to a thin plate orifice) so  that
 the water  does not contact  any  part  of the weir structure downstream
but,  rather,  springs  past  it,  the weir is called  a sharp-crested weir.
Figure 9  depicts  some common weir  terms and  their relationships.  As
noted,  the minimum height  of the weir crest  should be at least  two,  and
preferably three,  times  the maximum head  expected over  the weir.  The
 contraction of the nappe (overfalling stream) after springing clear of
 the sharp  crest  is termed crest contraction.   If the bottom of  the ap-
 proach channel is  not far enough below the  crest of the weir,  the crest
 contraction is partially suppressed,  and  standard weir  tables cannot be
 used.  The slight drop  in the liquid surface which begins  upstream from
 the weir a distance of at least twice the head on the crest is  called
                                    54

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TABLE 10.  SLOPE-AREA METHOD EVALUATION
Evaluation Parameter
1
2
3
4

5

6
7
8
9
10
11
12

13
14
15
16
17
18
19
20
21
22
23
24
25
Range
Accuracy
Flow Effects on Accuracy
Gravity & Pressurized Flow
Operation
Submergence or Backwater
Effects
Effect of Solids Movement
- Fl ow Obstruction
.Head Loss
Manhole Operation
Power Requirements
Site Requirements
Installation Restrictions
or Limitations
Simplicity and Reliability
Unattended Operation
Maintenance Requirements
Adverse Ambient Effects
Submersion Proof
Ruggedness
Self Contained
Precal ibration
Ease of Calibration
Maintenance of Calibration
Adaptabi 1 i ty
Cost
Portability
Scale
D Poor
& Poor
G3 High
& No

K High

D High
D High
D High
D Poor
D High
D High
D High

D Poor
D No
D High
D High
D No
Q Poor
D No
53 No
D Poor
D Poor
D Poor
K High
^ No
SI Fair ID Good
D Fair Q Good
D Moderate D Slight
DYes
ICO
D Moderate Q Low

D Moderate 53 Slight
D Moderate SI Slioht
D Medi urn 53 Low
D Fair 58 Good
D Medi urn 53 Low
53. Moderate Q S]ight
D Moderate 63 Slight

D Fair K Good
K Yes
D Medi urn S3 Low
gj Moderate Q Slight
DYes
D Fair j§3 Good
& Yes
D Yes
K Fair D Good
D Fair S3 Good
D Fair Q Good
D Medium D Low
D Yes
                 55 ,

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o
a.
to

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 surface contraction or drawdown.   To avoid sensing the effects of draw-
 down,  the gaging point should be  located upstream of the weir crest  a
 distance of at least three,  and preferably four,  times the maximum head
 expected over the weir.

 When the water level in the  downstream channel is sufficiently below
 the crest to allow free access to the area beneath the nappe,  say at
 least  15 cm (6 in.),  the flow is  said to be free  (critical).   When the
 water  level under the nappe  rises above the crest elevation,  the  flow
 may be considered submerged.   This may or may  not affect the  discharge,
 and there is some question whether dependable  measurements can be ex-
 pected in this range.  As the water  level downstream rises appreciably
 over half of the head on the crest,  the degree of submergence will ap-
 preciably affect the  rate of flow.   To determine  the rate of  flow under
 such submerged (sub-critical)  conditions,  both the upstream and down-
 stream heads must be  measured and reference made  to submerged  flow ta-
 bles.   A very good treatment of submerged weirs is given by Skogerboe,
 et  al  (22).

 Many different geometries have been  used for the  notch in the  weir
 plate  that shapes the nappe  and thereby allows the rating curve to be
 developed.   Some sharp-crested weir  profiles are  depicted in Figure  10.

 Rectangular  Weirs - One  of the oldest  and  most common is  the rectangular
 weir, which  is used in one of  two configurations.   When the distances
 from the sides of the weir notch  to  the sides  of  the  channel  (weir pool)
 are great enough (at  least two or three times  the head on the  crest)  to
 allow  the liquid a free,  unconstrained  lateral approach  to  the crest,
 the liquid will flow uniformly and relatively  slowly  toward the weir
 sides.  As the flow nears  the  notch  it  accelerates, and as it  turns  to
 pass through the opening,  it springs free  laterally with  a resulting
 contraction  that results in a  jet narrower  than the weir  opening.  Under
 such conditions  the weir is called a contracted weir.  If a rectangular
weir is placed in a channel whose sides  also act  as the sides  of the
weir, there  can be no lateral  contractions  and the weir is called a
 suppressed weir.   Special  care must be  taken with  these weirs  to assure
proper aeration beneath the nappe.  This is  usually accomplished by
placing vents  on both sides of the weir box under  the nappe.

V-Notch Weirs  - The triangular or V-notch sharp-crested weir was devel-
oped to allow  accurate measurement of small flows.  The angle  (2a) most
commonly used  is  90 degrees.   Because a V-notch weir has no crest
length, the head required for a small flow  through it is greater than
that required  for other common types of weirs.   This is an advantage
for small discharges in that the nappe will spring free of the crest,
whereas it might cling to the crest of another type of profile and make
the measurement worthless.  The V-notch weir is the best profile for
measuring discharges less than 28 t/s (1 cfs) and is as accurate as any
                                   57

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                                           "Vv  	X"
     RECTANGULAR
               2a
 TRIANGULAR OR V-NOTCH
               2a
TRAPEZOIDAL  (INCLUDING
      CIPOLLETTI)
                                                    2a
 INVERTED TRAPEZOIDAL
         POEBING
APPROXIMATE EXPONENTIAL
  APPROXIMATE LINEAR
 PROPORTIONAL  OR  SUTRO
         Figure 10.  Various Sharp-Crested Weir Profiles
                              58

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 other profile for flows up to 283 l/s (10 cfs).   Sufficient head for
 these higher flow rates may pose a limitation for many sites, however,
 and in practice 113 l/s (4 cfs) is often a more realistic upper bound.

 Trapezoidal Weirs - Trapezoidal weirs of varying side angles have been
 used to measure liquid flows, but the most common one by far is the
 Cipolletti, whose sides incline outwardly at a slope of one horizontal
 •to four vertical.  Although the Cipolletti weir  is a contracted weir,
 its discharge occurs essentially as though its end contractions were
 suppressed; thus the width of the crest  can be used for flow calcula-
 tions.   It offers a wider range than either the  rectangular or V-notch
 weir.

 Other Weirs - Other weir profiles,  as indicated  in Figure 10,  have been
 developed to achieve certain head-discharge relationships or to achieve
 some benefit peculiar to a particular type of site.   None of these has
 been used or investigated as extensively as those discussed above,  and
 consequently will not be dealt with here.   There is  one class  of spe-
 cial profiles,  however,  that at least deserves passing mention.   For
 situations where the normal range of discharges  at a site might be
 easily  handled by a V-notch weir but occasional  larger flows would re-
 quire,  for example,  a rectangular weir,  the two  profiles  have  been com-
 bined to  form what is termed a compound weir,  Figure 11.

 Such a weir has a disadvantage,  however.  While  flows  may be measured
 rather  accurately when the weir is  essentially behaving as a V-notch
 weir, Figure lla,  or as  a  rectangular (either  suppressed  or contracted)
 weir, Figure lib,  there will be a transition  zone where accurate  read-
 ings will  be difficult to  achieve.  When the discharge begins  to  exceed
 the  capacity of the  V-notch,  thin sheets of liquid will begin  to pass
 over the wide horizontal crests  in  a  less than predictable fashion.
 This causes  a discontinuity in  the  discharge curve.  The  size of  the
 V-notch and  the size of  the rectangular notch  should be selected so
 that discharge measurements  in  the  transition  range will be those of
minimum importance.

Discussion -  In order  to have a  satisfactorily-operating sharp-crested
weir, the following general requirements should be considered:

     a.
     b.
   ...upstream face of the structure should be smooth and
perpendicular to the axis of the channel in both hori-
zontal and vertical directions.

The crest should be level, with a sharp right-angled edge
on its upstream face; its thickness (in the direction of
the flow) should not exceed 3 mm (1/8 in.) and should
preferably be between 1 to 2 mm (0.04 to 0.08 in.).
Knife edges should be avoided as they are too difficult
to maintain.
                                  59

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      Ca)
    \/
       Cb)
Figure 11. Compound Weir
        60

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     c.  The height of the crest above the approach channel bottom
         should never be less than 0.3m (1 ft); the minimum head
         should be at least 0.06m (0.2 ft).  For- a contracted
         rectangular weir, the distance from the sides of the
         weir to the sides of the approach channel should never
         be less than 0.3m (1 ft).

     d.  The cross-sectional area of the approach channel should
         be at least 8 times that of the nappe at the crest for a
         distance upstream of 15 to 20 times the height on the
         crest.  If the weir pool is smaller than this, the veloc-
         ity of approach may be too high and the gage readings too
         low; necessitating head corrections for velocity of
         approach.

     e.  The connection between the weir and the channel must be
         waterproof; i.e., all flow must pass over the weir, not
         around or under it.

In general, the sharp-crested weir is an inexpensive, accurate primary
flow measuring device that is fairly easy to install.  Laboratory accu-
racies approaching 1% of full scale have been achieved, but 5% is more
typical of most good field installations.   The operating range of a
sharp-crested weir depends upon its profile, but 20:1 may be considered
typical for many installations.  The sharp-crested weir suffers from
several deficiencies when considered for a storm or combined sewer ap-
plication, however.  It may well require construction of a weir box to
obtain the proper flow approach to the weir.  Sufficient head may not
be available at the desired measuring site, and the head loss will be
at least equal to the head measured.  The crest of the weir must be
kept clean.  Fibers, stringy materials, and larger particles tend to
cling to the crest and must be removed periodically.

Finally, because of its damming action, the sharp-crested weir will
suffer from settling and accumulation of suspended solids in the ap-
proach channel behind the upstream face.  This will lead to inaccurate
readings.  Some weirs have been constructed with a watertight door in
the face on the channel bottom.  When the door is opened the flow will
go through this passage and tend to scour away collected sediment.
However, most attempts to use charp-crested weirs in extremely dirty
flows have been less than fully successful.  Sharp-crested weirs are
evaluated as a group in Table 11.

Submerged Orifices - The use of thin-plate orifice meters in pressur-
ized conduit flow has already been discussed.  In open channel flow, an
orifice operates as a head-area device; in fact, if the water level
drops below the top of the opening,  it behaves like a weir and has been
included here for that reason.  Basically; it consists of a predeter-
mined, sharp-edged opening in a plate affixed to a wall or other
                                   61

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TABLE 11.  SHARP-CRESTED WEIR EVALUATION (ALL
                  PROFILES)
Evaluation Parameter
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
Range
Accuracy
Flow Effects on Accuracy
Gravity & Pressurized Flow
Operati on
Submergence or Backwater
Effects
Effect of Solids Movement
Flow Obstruction
Head Loss
Manhole Operation
Power Requirements
Site Requirements
Installation Restrictions
or Limitations
Simplicity and Reliability
Unattended Operation
Maintenance Requirements
Adverse Ambient Effects
Submersion Proof
Ruggedness
Self Contained
Precal i bration
Ease of Calibration
Maintenance of Calibration
Adaptabi 1 i ty
Cost
Portability
Seal e
D Poor
C3 Poor
D High
KJ No
D High
B High
63 High
18 H i g h
D Poor
D High
D High
D High
D Poor
D No
63 High
D High
D No
D Poor
D No
D No
D Poor
53 Poor
D Poor
D High
D No
63 Fair
63 Fai r
8! Moderate

53 Moderate
D Moderate
D Moderate
D Medi urn
53 Fair
D Medi urn
S! Moderate
53 Moderate
D Fair

D Medi urn
SI Moderate

D Fair


D Fair
D Fair
D Fair
D Medi urn

D Good
D Good
D Slight
D Yes
D Low
D Slight
D SI ight
D Low
D Good
53 Low
D Slight
D S 1 i g h t
SIxGood
63 Yes
D Low
D Slight
D Yes
63 Good
63 Yes
63 Yes
53 Good
D Good
D Good
63 Low
Kl Yes
                      62

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 structure and through which flow may occur.  Although any  shape hole
 can be used,  the most common are either  circular  or  rectangular.  Know-
 ledge of the  size  and shape of  the  hole,  the head acting on it, and the
 discharge condition (i.e.,  freely into air or under  water) allows de-
 termination of the flow rate.   Early orifices often  discharged freely
 into air,  but were practically  abandoned  as weirs become more common
 (and more extensively studied)  because of the considerable head loss
 necessitated  by their use.

 The fall requirement  is reduced if  the orifice is lowered in the struc-
 ture and discharges in  the  submerged condition.   The submerged orifice
 is  used where the  head  loss of  a weir cannot be tolerated and a flume
 cannot be justified because of  cost or some special  conditions.  Like
 the weir,  a submerged orifice may be either contracted or suppressed.
 Suppression may occur on part (e.g.,  the  bottom of a rectangular orifice
 flush with the channel  flow) or all of the perimeter.

 In  selecting  a channel  site for use of a  submerged orifice meter the
 distance from the  edges  of  the  orifice to the bounding surfaces of the
 channel, both on the  upstream and downstream sides,  should be greater
 than twice the least  dimension  of the orifice if  contraction is to be
 assured.   Also,  the cross-sectional  area  of the water prism 6 to 9 m
 (20  to 30  ft)  upstream  from the orifice should be at least 8 times the
 cross-sectional  area  of  the  orifice.  Velocity of approach to the ori-
 fice  should be negligible, or correction must be made for velocity head.

An orifice should not be used in situations where weeds and trash are
prevalent, as  accumulation of submerged debris or of sand and sediment
upstream may prevent accurate measurements.   A clogged condition of an
orifice  is less visible  than that of a weir and, so, may go undetected.
Because  of these factors and the small data base as compared to weirs
and flumes, an orifice is not generally recommended for measurement of
stormwater or  combined sewage,  even  though its limited range of flow
can be increased with the use of a metergate,  which basically is a
modified submerged orifice arranged so that the orifice is adjustable
in cross-sectional area.  Consequently, no further discussion or evalu-
ation will be  given.

Broad-Crested Weirs - If the weir notch is mounted in a wall too thick
for the water  to spring past, the weir is called broad-crested.   A wide
variety of shapes can be included under broad-crested weirs,  and a wide
variety of discharge coefficients will be encountered.   A few such
shapes are depicted in Figure 12.  Broad-crested weirs,  in practice,
are usually pre-existing structures, such as  dams, levees,  diversion
structures, etc.  Discharge coefficients and  discharge tables  are usu-
ally obtained by calibrating the weir in place or by model studies.
Broad-crested weirs are sometimes used where  the sharp-crested weir
causes undue maintenance problems.   For example,  problems  with impact,
                                   63

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          t\
11
 o
 _I
 u_
           64

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abrasion, silting, etc. might indicate the need for a broad-crested
weir.  Broad-crested weirs are usually made of concrete or similar ma-
terial and are not considered portable.  In actuality, the notion of a
broad-crested weir, which simply denotes a channel contraction made by
a sill on the channel bottom, merges into that of a critical-depth
flume.  When properly designed and constructed, the broad-crested weir
is governed by the same basic flow equations.  Broad-crested weirs are
evaluated in Table 12.

Flumes

Although the term "broad-crested weir" is widely used to denote a chan-
nel constriction made by some sort of a sill on the channel bottom,
other open channel constrictions, generally called flumes, have been
used to measure discharges since the beginning of the century.  Most
flumes in common use today can be traced to one of three early design
sources:  rectangular English flumes based upon early work in India
around 1908-1914 and the writings of F. V. A. E. Engal (23); the
Parshall flume whose forerunner, a venturi flume developed by Cone (24),
was extensively modified and tested by Parshall (25, 26); and flumes of
the type first developed by Palmer and Bowlus (27).

Flumes can be categorized as belonging to one of three general families
depending upon the state of flow induced - subcritical, critical, or
supercritical.  By definition the critical flow state is that for which
the-Froude number is unity.  This is the state of flow at which the spe-
cific energy is minimum for a given discharge.  When critical depth
occurs in a channel (either at a constriction or in a regular cross-
section) , one head measurement can indicate discharge rate if it is
made far enough upstream so that the flow depth is not affected by the
drawdown of the water surface as it heads to achieve the critical state
of flow.

Kilpatrick (28) identifies six approaches employed in various flume de-
signs, and these will be briefly treated below following his discussion.

Type I, tranquil-flow, small-width reduction flumes are typical of the
earliest measuring flumes and are depicted in Figure 13.  Subcritical
flow enters the flume, and the side contractions reduce the width, re-
sulting in an increase in unit discharge.  Because there is no change
in bed elevation, and minor energy loss, the specific energy in the
throat is about the same as in the approach.  With constant specific
energy, the effect of a small width contraction is a lowering of the
water surface in the throat but, owing to the small degree of contrac-
tion, critical depth is not accomplished.  It is necessary in this type
of flume to measure the head in both the approach section and in the
throat.
                                   65

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TABLE 12.  BROAD-CRESTED WEIR EVALUATION
Evaluation Parameter
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
Range
Accuracy
Flow Effects on Accuracy
Gravity & Pressurized Flow
Operation
Submergence or Backwater
Effects
Effect of Solids Movement
Flow Obstruction
Head Loss
Manhole Operation
Power Requirements
Site Requirements
Installation Restrictions
or Limitations
Simplicity and Reliability
Unattended Operation
Maintenance Requirements
Adverse Ambient Effects
Submersion Proof
Ruggedness
Self Contained
Precal ibration
Ease of Calibration
Maintenance of Calibration
Adaptabi 1 i ty
Cost
Portabi 1 i ty
Scale
D Poor
n Poor
D High
Si No
E9 High
8) High
D High
D H i g h
D Poor
D High
D High
D High
D Poor
D No
D High
D High
D No
D Poor
D No
8J No
D Poor
D Poor
D Poor
D High
SI No
8j Fair D Good
81 Fair D Good
D Moderate Si Slight
D Yes
D Moderate Q Low
D Moderate D Slight
63 Moderate D Slight
81 Medi urn D Low
D Fair 8! Good
D Medi urn SI Low
8! Moderate D Slight
81 Moderate D Slight
D Fair 62 Good
8l Yes
D Medium SI Low
81 Moderate D Slight
D Yes
D Fair 81 Good
81 Yes
D Yes
SI Fair D Good
SI Fair D Good
D Fair D Good
D Medi urn 8] Low
D Yes
                   66

-------
 Type II,  critical-flow,  large-width reduction flumes are illustrated in
 Figure 14 and differ from Type I flumes only in that the throat contrac-
 tion is sufficient to ensure that critical flow is achieved.   This gives
 the advantage of requiring measurement at only one location,  which may
 be either in the immediate approach to the flume or in the throat.
 Measurement in the approach will yield a more sensitive stage-discharge
 relationship because changes in discharge will result in greater changes
 in depth  in subcritical  flow than would like changes in discharges in
 critical  flow.   Unfortunately,  the stage-discharge relationship in the
 approach  may be unstable due to approach conditions such as scour and
 fill.   Consequently,  stage is usually  measured in the throat  to allevi-
 ate influence from either upstream or  downstream.   Approach conditions
 can have  some effect on  flow in the throat,  but it is generally insig-
 nificant.   The  site at which critical  depth  is first reached  may shift
 further downstream into  the throat as  a result of excessive deposition
 in the  approach.   For this reason,  and to avoid possible flow separa-
 tions near  the  entrance,  stage  measurements  in the throat should not  be
 too close to  the entrance.   Flow close to critical is very unstable,
 constantly  attempting to  become either subcritical or supercritical.
 Therefore,  this  type  of  flume is seldom encountered in practice.

 Type III, tranquil-flow,  small-increase-in-bed elevation flumes  are
 shown in  Figure  15.   Because of the requirement for dual gaging  points
 and the partial  barrier to  the  approaching flow, which will encourage
 deposition  of suspended solids,  such designs are not commonly used.

 Type IV,  supercritical-flow, width-reduction,  steep-slope  flumes  are
 illustrated in Figure 16.   For  flumes  that have bed slopes  of near zero,
 critical  depth is  the minimum depth possible in the flume.  Further con-
 traction, £either at the sides or bottom, will  not  produce  supercritical
 flow.   This can be accomplished only by  increasing the available  spe-
 cific energy from  the approach  into  the  throat.  For  Type IV  flumes,
 the  bed is  placed on  a slope sufficient  to cause the  required increase
 in specific energy to produce supercritical flow in  the  throat.   It may
 be thought  of as a Type II  flume tilted  in the  downstream direction.
 Only a  single gaging point  is required.

 Type V, supercritical-flow, width-reduction, drop-in-bed flumes are
 depicted in Figure 17.  Here the increase in specific energy required
 to achieve  supercritical flow is provided by a sudden drop in the bed.
Measurement of head is made either in the throat or the approach.  A
 discharge rating based upon measurements in the region of supercritical
 flow, while not as sensitive as compared with measurements in subcriti-
 cal  flow, is the least influenced by disturbances either upstream or
 downstream, and hence is apt to be the most stable.  Similarly, such
 flumes are the most capable of stable operation up to high submergences.
                                   67

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        FLOW
                           DUAL  GAGING
                             POINTS
                                                        PLAN VIEW
                                                       ENERGY  LINE

                                                       WATER SURFACE
ELEVATION
CRITICAL
DEPTH LINE
    Figure 13.  Type I Flume - Critical Flow Contraction Obtained by
                 Small Width Reduction, Horizontal Bed
               Y/////////////////S
         FLOW
 ELEVATION
                             ALTERNATE
                           GAGING POINTS
                                                          PLAN VIEW
   ENERGY LINE

   WATER SURFACE

   CRITICAL
   DEPTH LINE
    Figure 14.   Type II Flume - Critical Flow Contraction Obtained by
                  Large Width Reduction, Horizontal Bed
                                   68

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  FLOW
                                                   PLAN VIEW
                       ALTERNATE
                     GAGING POINTS
ELEVATION
                                                - ENERGY  LINE
                                                  WATER SURFACE
                                                  CRITICAL
                                                  DEPTH  LINE
Figure 16.   Type IV Flume - Supercritical Flow Contraction Obtained
               by Width Reduction and Sloping Bed
    FLOW'
 ELEVATION,
                                                     PLAN  VIEW
                         ALTERNATE
                       GAGING POINTS
                                                      ENERGY LINE
                                                      WATER SURFACE
                                                      CRITICAL
                                                      DEPTH  LINE
                                 y////////////////////'
 Figure 17.  Type V Flume - Supercritical Flow Contraction Obtained
                by Width Reduction and Drop in Bed
                                  70

-------
 Type VI,  supercritical-flow,  steep-slope flumes are illustrated in Fig-
 ure 18.   Here there is no contraction,  the increase in specific energy
 necessary for achieving supercritical flow being produced simply by
 producing sufficient downstream slope.   Although a slope of one degree
 is usually sufficient to produce critical depth in the vicinity of the
 upstream  edge of the apron, waves and disturbances are apt to  be numer-
 ous downstream.   For this reason slopes on ordinary concrete aprons
 will more typically range from 2 to  5%.

 Site Selection - A few recommendations  for the selection of gaging sites
 apply in  general to all types of commonly-encountered  flumes.   The
 flumes should be located in a straight  section of channel without bends
 immediately upstream.   The approaching  flow should be  well distributed
 across the channel,  and relatively free of turbulence, eddies,  and
 waves.  Generally,  a site with high  velocity of approach should not be
 selected.   But,  if  the water  surface just upstream is  smooth with no
 surface boils, waves,  or high-velocity  current concentrations,  accuracy
 may not be greatly  affected by velocity of approach.

 Consideration should be given to the height of upstream banks,  noting
 their ability to sustain the  increased  depth caused by the flume in-
 stallation.   Although  less head is lost through flumes than over weirs,
 particularly if  flat-bottomed flumes are used,  losses  may  be signifi-
 cant with  large  installations.   The  possibility of  submergence  of  the
 flume due  to backwater  from downstream  must also be investigated,  al-
 though the effect of submergence upon the accuracy  of  most  flumes  is
 much less  than is the case with weirs.

 Subcritical  (Venturi) Flumes  -  Subcritical  flumes are  called true ven-
 turi type  flumes by  some researchers, e.g.,"Replogle (8), probably be-
 cause of their requirement for  the measurement  of flow levels at two
 positions.   The  Type I and III  flumes discussed earlier  are  examples of
 designs of such  devices.   Because of  their  advantage of  requiring only a
 single measurement,  supercritical^flumes  are generally preferred design
 approaches and,  consequently, Subcritical flumes are not often installed
 today.  They are evaluated in Table  13.         ,

 Parshall Flume - The development of many  early flumes arose from the
 need  to measure irrigation flows, and the Parshall flume is no excep-
 tion.  The earlier designs were Types I,  II, and III flumes, and the
 essential change introduced by Parshall was a drop in the floor which
 produced supercritical flow through the throat  (Type V).  Today the
Parshall flume is the most widely used primary device in the head-area
 classification for the measurement of sewage and other wastewater.  The
 configuration and standard nomenclature for Parshall flumes is  given in
Figure 19.  For a given throat width  (W), all other dimensions  are rig-
 idly prescribed.   Since the rating tables for Parshall flumes are based
upon extensive and meticulous research, faithful adherence to all dimen-
 sions is necessary to achieve accuracy.
                                   71

-------
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                                  72

-------
TABLE 13.  SUBCRITICAL (VENTURI) FLUME EVALUATION
Evaluation Parameter
1
2
3
4

5

6
7
8
9
10
11
12

13
14
15
16
17
18
19
20
21
22
23
24
25
Range
Accuracy
Flow Effects on Accuracy
Gravity & Pressurized Flow
Operation
Submergence or Backwater
Effects
Effect of Solids Movement
Flow Obstruction
Head Loss
Manhole Operation
Power Requirements
Site Requirements
Installation Restrictions
or Limitations
Simplicity and Reliability
Unattended Operation
Maintenance Requirements
Adverse Ambient Effects,
Submersion Proof
Ruggedness
Self Contained
Precal ibration
Ease of Calibration
Maintenance of Calibration
Adaptability
Cost
Portabi 1 ity
Scale
D Poor
D Poor
D High
81 No

D High

D High
D High
DHigh
D Poor
D High
D High
D High

D Poor
D No
D High
D High
D No
D Poor
D No
D No
D Poor
O Poor
D Poor
D High
&! No
SI Fair D Good
SI Fair D Good
D Moderate S3 Slight
D Yes

D Moderate O Low

D Moderate Bl Slight
D Moderate SI Slight
D Medi urn S) Low
S3 Fair D Good
D Medi urn 81 Low
SI Moderate D Slight
D Moderate H Slight

D Fair 8! Good
81 Yes
D Medium 63 Low
18 Moderate Q Slight
D Yes
D Fair E) Good
SI Yes
K Yes
D Fair Sj Good
D Fa.i r SI Good
D Fair D Good
SJ Medi urn Q Low
D Yes
                      73

-------
                 NOTE:  7.6cm (3in) TO 2.4m (8ft) FLUMES HAVE
                       ROUNDED APPROACH WINGWALLS

                        ANGLE
                              . SECTION L-L
                                                           ANGLE
   LEGEND:  .

   W       Size'of flume,  In inches or feet.
   A       Length of  side  wall of converging  section.
   2/3A    Distance back from end of crest to gage point.
   B       Axial  length of converging section.
   C       Width  of downstream end of flume.
   D       Width  of upstream end of flume.
   E       Depth  of flume.
   F       Length of  throat.
   G       Length of  diverging section.
   K       Difference in elevation between lower end of  flume  and  crest.
   H       Depth  of depression in throat below crest.
   R       Radius of  curved wing wall.
   H       Length of  approach floor.
   P       Width  between ends of curved wing  walls.
   X       Horizontal'distance to Hfa gage point from low point in  throat.

   Y       Vertical distance to Hb gage point from low point  in  throat.



Figure 19.  Configuration  and  Standard Nomenclature for

                         Parshall  Flumes
                                  74

-------
 The earlier Parshall flumes were developed in sizes  (throat widths)
 ranging from 7.6 cm (3 in.) to 2.4m (8 ft).  More recently, Robinson
 (29) has calibrated Parshall flumes of 2.5 cm (1 in.) and 5.1 cm (2 in.)
 in size.  Flumes with throat widths of 3 to 15m (10  to 50 ft) have been
 constructed and field calibrated.  Head-discharge ratings are thus
 available for a large range in throat width.  Table  14 is presented to
 give the reader a "feel" for the dimensions and capacities of all sizes
 of standard Parshall flumes.

 Flow through a Parshall flume may be either free or submerged.  In free
 flow,  only the upstream head (Ha) need be measured, and this condition
 is favored for accurate measurement.   Where free-fall conditions exist
 for all flows, the downstream (Hb) may be omitted and the entire di-
 verging section left off if desired,  assuming channel erosion is no
 problem.  This simplification has been used in the design of small port-
 able Parshall flumes.

 Submerged flow exists when the water  surface elevation downstream of
 the flume is high enough to affect the head and  retard the rate of dis-
 charge.  The degree of  submergence is  indicated  by the ratio of the
 downstream head to the  upstream head  (Hb/Ha).  If  the ratio is greater
 than 0.6 for flumes under 0.3m (1 ft)  or  0.7 for flumes in the 0.3 to   (
 2.4m (1 to 8 ft)  range,  flow must be  considered  to be submerged and
 corrections must  be made according to  the degree of submergence.  A
 complete treatment of the subject is given by  Skogerboe,  et al (30,  31).

 Small  solids in suspension are readily carried through Parshall  flumes
 and do not affect the measurement accuracy, which  should  range between
 1.5 percent (virtually  the best obtainable)  to 5 percent  (more typical
 of  good field  installations).   Errors  greater  than this are frequently
 found,  the chief  causes being  either dimensional inaccuracies  or im-
 proper flow conditions.   Although Parshall  flumes  are self-cleaning,
 large  rocks  and other debris in the flow may cause problems.   Kilpatrick
 (28) notes  that,  "it& uAe. on filaAhy, co66£e-4^ewn .a-tteama  ha* be.e,n n.oJL-
 Otlvely u^uccei^ae."  Another problem with the use  of a Parshall flume
 in measuring dirty  flows  such as  sewage is  that  sometimes the  installa-
 tion must  differ  from the standard  so as to prevent deposition of mate-
 rial upstream from  the flume.  Such non-standard entrance transitions
 can result in discharges  that are quite different from standard values
 as pointed out by Chen, et  al  (32).

 The head loss required for  flow measurement with a Parshall flume is
 quite small.  There must be a way to achieve the required drop in the
 floor,  however, and this will eliminate some sites from consideration.
Parshall flumes are evaluated in Table 15.

Palmer-Bowlus Flume - Flumes of the type first suggested and developed
by Palmer and Bowlus (27) are a form of Type IV flume, being dependent
                                   75

-------

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-------
TABLE 15.  PARSHALL FLUME EVALUATION
Evaluation Parameter
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
Range
Accuracy
Flow Effects on Accuracy
Gravity & Pressurized Flow
Operation
Submergence or Backwater
Effects ,
Effect of Solids Movement
Flow Obstruction
Head Loss
Manhole Operation
Power Requirements
Site Requirements
Installation Restrictions
or Limitations
Simplicity and Reliability
Unattended Operation
Maintenance Requirements
Adverse Ambient Effects
Submersion Proof
Ruggedness
Self Contained
Precal i brati on
Ease of Calibration
Maintenance of Calibration
Adaptability
Cost
Portability
Scale
D Poor
D Poor
D High
59 No
D High
D High
D High
D High
D Poor
D High
D High
D High
D Poor
D No
O High
D High
D No
D Poor
D No
n NO
D Poor
D Poor
D Poor
n High
D No
D Fair 53 Good
53 Fair Q Good
D Moderate 51 Slight
D Yes
59 Moderate Q Low
D Moderate 59, Slight
D Moderate 59 Slight
D Medium 58 Low
S) Fair D Good
D Medium 69 Low
59 Moderate D Slight
59 Moderate DSliciht
D Fai r 59 Good
53 Yes
D Medi urn 53 Low
59 Moderate Q Slight
D Yes
D Fair 53 Good
53 Yes
69 Yes
D Fair 59 Good
D Fai r 59 Good
D Fair D Good
S3 Medi urn D Low
59 Yes
                77

-------
upon existing conduit slope and a channel contraction (provided by the
flume) to produce supercritical flow.  Ludwig and Ludwig (33) and Wells
and Gotaas (34) have discussed various design aspects of such flumes.
Such flumes arose out of a desire to have a measurement device that
could be inserted into an existing conduit with minimal site require-
ments other than sufficient slope.  A number of different cross-section
shapes have been used over the years.  Typical shapes for round and
rectangular conduits are depicted in Figure 20.  A proprietary flume,
the Leopold-Lagco, which was introduced in 1965, is a Palmer-Bowlus
type flume with a rectangular cross-section and is designed for use
with circular pipes.

In the detailed laboratory studies conducted by Wells and Gotaas  (34),
they found that accuracies within ±3% of the theoretical rating curve
could be obtained at depths as great as 90% of the pipe diameter.  No
effect of downstream depth on calibration was found for submergence
ratios less than 0.85.  Various geometric effects were investigated, and
it was found that a minimum throat length of at least 60 percent  of -the
pipe diameter was required, that the base height and exit transitions
had no effect on the calibration, that a variation of entrance transi-
tion slope from 1:3 to 1:2 had a negligible effect, and that the  point
of upstream depth measurement should be no more than half of the  pipe
diameter upstream from the entrance to the flume.

In some designs, e.g., Figure 20c, the bottom slab or base is omitted
entirely.  It is more often included, however, both to help  distrxbute
the overall channel contraction and  to provide structural integrity, an
important feature for portable devices especially.

The chief advantage of Palmer-Bowlus  flumes over Parshall flumes  is
their ease of  installation in existing conduits.  They may also offer
somewhat  lower head loss.  They share all  of the benefits listed  in  the
discussion of  Parshall flumes.  In ordinary designs operating under  low
flow  conditions,  the bottom  slab  acts as a broad-crested weir, whose
characteristics were discussed  earlier.  A disadvantage of Palmer-Bowlus
flumes is that they have a smaller range,  with 20:1 being seldom ex-
ceeded.   Standard Palmer-Bowlus  flumes are available  to fit  pipe sizes
from 15.2 cm (6  in.)  to  2.4m (8  ft).  Palmer-Bowlus  flumes are  evaluated
in Table 16.

As stated'by Palmer and Bowlus  (27), "The. Important facto* ^Ln the. con-
&&w.c£Lon and ^Ln&taUation o& any &om o$  ve.ntu^L devx.ce *J>  tlnat a con-
Atniction 06 &om the.y meet the.
•ipecac pfiobtm at hand Jin a practical manned."  Diskin (35)  has in-
 troduced an unconventional sort of a Palmer-Bowlus flume,  Figure 21.
 He achieved channel contraction by wedging a pier-shaped element in
                                     78

-------
   END  VIEW
 (a)
  LONGITUDINAL MID SECTIONS
  VERTICAL          HORIZONTAL
                 c
 (b)  J
0
c
Cc)
     -fILf—*~-~-f:-tftI_
(d)
'•
rf

                                       •A. \»\A A^
    Figure 20.  Various  Cross-Section Shapes
            of Palmer-Bowlus Flumes
                         79

-------
TABLE 16.  PALMER-BOWLUS FLUME EVALUATION
Evaluation Parameter
1
2
3
4

5

6
7
8
9
10
11
12

13
14
15
16
17
18
19
20
21
22
23
24
25
Range
Accuracy
Flow Effects on Accuracy
Gravity & Pressurized Flow
Operation
Submergence or Backwater
Effects
Effect of Solids Movement
Flow Obstruction
Head Loss
Manhole Operation
Power Requirements
Site Requirements
Installation Restrictions
or Limitations
Simplicity and Reliability
Unattended Operation
Maintenance Requirements
Adverse Ambient Effects
Submersion Proof
Ruggedness
Self Contained
Precal i brati on
Ease of Calibration
Maintenance of Calibration
Adaptability
Cost
Portabi 1 ity
Scale
D Poor
Q Poor
D High
Si No

D High

D High
n High
DHigh
D Poor
D High
D High
D High

D Poor
D No
D High
D High
D No
D Poor
D No
D No
D Poor
D Poor
D Poor
D High
D No
Si Fair
SI Fair
n Moderate


SI Moderate

D Moderate
D Moderate
D Medium
D Fair
D Medium
O Moderate
D Moderate

D Fair

D Medium
SI Moderate

D Fair


D Fair
D Fair
D Fair
D Medi urn

D Good
D Good
18 Slight
D Yes

n LOW

8 Slight
SI Slight
SI Low
SI Good
SI Low
SI Slight
SI Slight

SI Good
SI Yes
SI Low
D Slight
D Yes
SI Good
SI Yes
SI Yes
SI Good
S) Good
D Good
SI Low
SJ Yes
                    80

-------
         WATER SURFACE
    VERTICAL CROSS-SECTION
7
   r OPENING
   /  (ABOVE)
                                         END  VIEW
-WEDGE
 (ABOVE)  ^PRECAST ELEMENT
          MEASURING POINT
           TOP VIEW
       Figure 21.  Diskin Measuring Device
                       81

-------
the pipe between the crown and the invert.  Experimental observations
confirmed the theoretical rating curve determined under the same as-
sumptions as for a standard Palmer-Bowlus flume.  Limiting submergence
was found to be between 0.75 and 0.85.

The chief drawback to such a metering device is that it poses a severe
obstruction to the flow and, if applied to trashy or debris-laden flows,
it almost surely invites, in time, either its own destruction or block-
age of the conduit.  As a portable device, however, it can be installed
quickly and may have some use.  The Diskin device is evaluated in
Table 17.

Cutthroat Flume - The cutthroat flume was developed for use in flat
gradient channels where a flume which could operate satisfactorily
under both free (critical) flow and submerged flow conditions might be
desired.  It operates as either a Type I or Type II flume.  The advan-
tages of a flume with a level floor are that it is easy to construct
and can be placed inside an existing channel without requiring excava-
tion, simply by placing it on the channel bed.  Studies reported by
Skogerboe, et al (30) showed that flow depths measured in the exit sec-
tion of the flume resulted in more accurate submerged flow calibration
curves than calibrations employing flow depths measured in the throat
section.  Since the upstream depth measurement is made near the en-.
trance, there is no need for a throat section in such a flume; in fact,
removing the throat section was found to improve flow conditions in the
exit section.  Skogerboe, et al (36), who performed the development work
on these flumes, have given the name "Cutthroat" to any such flume that
has no throat section (i.e., zero throat length).  A rectangular cut-
throat flume is illustrated in Figure 22.

One of the benefits of a cutthroat flume is economy, since fabrication
is facilitated by  the flat bottom and removal of the throat section.
Another fabrication advantage is that every flume  size has the same wall
lengths, which allows the same forms or patterns to be used for every
flume size.  Rectangular cutthroat flume  sizes  of  0.3, 0.6, 0.9, 1.2,
and 1.8m  (1, 2, 3, 4, and 6 ft) have been studied  extensively by
Skogerboe,  et al  (36).  Transition submergences were found to vary
smoothly  from 79%  to  88% over this range.  Above these values, the  flow
is subcritical  (submerged)  and the submerged  flow  calibration curves
must be used.

Similar cutthroat  flumes of a trapezoidal shape with sides sloping  out-
ward at 45  degrees were  also  investigated by  Skogerboe,  et al  (36)  in
small  sizes, i.e., throat widths  of  0,  15,  and  30  cm  (0,  6,  and  12  in.).
Development of  intermediate and  larger  sizes  was not attempted because
of the variety  of  possible  geometries that  could be used.  Cutthroat
 flumes are evaluated in  Table 18.
                                    82

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TABLE 17.  DISKIN DEVICE EVALUATION
Evaluation Parameter
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
Range
.Accuracy
Flow Effects on Accuracy
Gravity & Pressurized Flow
Operation
Submergence or Backwater
Effects
Effect of Solids Movement
- Flow Obstruction
Head Loss
Manhole Operation
Power Requirements
Site Requirements
Installation Restrictions
or Limitations
Simplicity and Reliability
Unattended Operation
Maintenance Requirements
Adverse Ambient Effects
Submersion Proof
Ruggedness
Self Contained
Precal ibration
Ease of Calibration
Maintenance of Calibration
Adaptability
Cost
Portabi 1 i ty
Scale
D Poor
D Poor
D High
8 No
D High
D High
E High
DHigh
D Poor
D High
D High
D High
D Poor
& No
K High
Si High
D No
D Poor;
D No
D No
D Poor
D Poor
D Poor
13 High
D No
K Fair DGood
58 Fair Q Good
D Moderate S) Slight
D Yes
53 Moderate Q Low
$3 Moderate D Slight
D Moderate D Slight
D Medium 53 Low
D Fai r SI Good
D Medium SI Low
D Moderate 58 Slight
D Moderate S! Slight
D Fair SI Good
D Yes
D Medium D Low
D Moderate Q Slight
D Yes
S3 Fair Q Good
& Yes
85 Yes
81 Fair Q Good
E3 Fair D'Good
D Fair D Good
D Medium S3 Low
» Yes
             83

-------
                       6.081
STILLING  WELL
STILLING WELL
FOR H.
                                             CM
                                             +
                                            SUBMERGED
                                            FLOW
                                            TRANSITION
                                            FREE FLOW
                 ELEVATION
Figure 22.   Rectangular Cutthroat Flume
                        84

-------
TABLE 18.  CUTTHROAT FLUME EVALUATION
Evaluation Parameter
1
2
3
4

5

6
7
8
9
10
11
12

13
14
15
16
17
18
19
20
21
22
23
24
25
Range
Accuracy
Flow Effects on Accuracy
Gravity & Pressurized Flow
Operation
Submergence or Backwater
Effects
Effect of Solids Movement
- Flow Obstruction
Head Loss
Manhole Operation
Power Requirements
Site Requirements
Installation Restrictions
orL imitations
Simplicity and Reliability
Unattended Operation
Maintenance Requirements
Adverse Ambient Effects
Submersion Proof
Ruggedness
Self Contained
Precal ibration
Ease of Calibration
Maintenance of Calibration
Adaptability
Cost
Portabi 1 ity
Scale
D Poor
D Poor
D-High
& No

D High

D High
D High
DHigh
KJ Poor
D High
D High
D High

D Poor
D No
D High
D High
D No ,
D Poor
D No
D N.o
D Poor
D Poor
D Poor
D High
Si No
D Fair
53 Fair
D Moderate


D Moderate

D Moderate
D Moderate
D Med i urn
D Fair
D Medium
D Moderate
D Moderate

D Fair

D Medi urn
SI Moderate

D Fair


D Fair
D Fair
D Fair
CD Medi urn

S3 Good
D Good
Kl Slight
D Yes

S3 Low

K Slight
Kl Slight
S3 Low
D Good
^ Low
S Slight
K Slight

S) Good
8 Yes
81 Low
D Slight
D Yes
£3 Good
S Yes
SI Yes
SI Good
SI Good
D Good
SI Low
D Yes
                85

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Other Flumes - Several other flume designs have been used to solve spe<-
ciflc problems.  These flumes may:  (a) be easier to construct for cer-
tain types of sites; (b) pass sediment-laden flows more readily;
(c) handle a wider range of flows under certain conditions; (d) have
increased sensitivity in a particular flow range; etc.  As a general
rule, they have not been as extensively investigated as the Parshall
or Patoer-Bowlus flumes, and less is known about their behavior over
a wide range of conditions.

San Dimas Flumes - As an example, the San Dimas flume was developed to
measure debris-laden flows in the San Dimas Experimental forest in 1938.
It is a modified Type IV flume in that it uses lateral contraction plus
a 3% slope in its floor to create a supercritical flow.  In the entry,
the floor rises quickly to the crest, after which it falls as indicated
in Figure 23a.  Because head measurements are made in supercritical
flow in the throat and critical depth occurs upstream, the discharge
ratings should be independent of upstream and downstream distubances.
Variation in approach conditions also should have little effect on the
ratings.  Because of its rectangular cross-section, the San Dimas flume
is not sensitive or accurate at low flows.  Results of tests on modified
San Dimas flumes were reported by Bermel (37), who reduced the degree of
contraction of the flume relative to the natural channel, provided a
less abrupt entrance, and measured the head at the midpoint of the flume
regardless of length.  The modified San Dimas flume is depicted in Fig-
ure 23b.  San Dimas flumes are evaluated in Table 19.

Trapezoidal Flumes - In attempts  to obtain wider ranges of discharge
than those that can be obtained with Parshall or San Dimas flumes, sev-
eral investigators have considered supercritical trapezoidal flumes.
These generally operate as Type IV flumes.  The outward sloping of the
flume walls provides increased sensitivity to lower discharge rates for
a given size and, hence, increased range.  The possible elements of a
trapezoidal flume are indicated in the isometric sketch in Figure 24.
All of these elements need not be included in a particular design, how-
ever.  In the  trapezoidal cutthroat  flume discussed earlier, for exam-
ple, the throat section is absent.  Other designs eliminate the
diverging and  exit  sections where channel erosion is not a problem, and
so on.

Serious investigations  of  trapezoidal  flumes began  to be reported in
increasing numbers  in  the  late 1950s.  Geometric variations are so nu-
merous  that no attempt will be made  here to describe  them  all.  Robinson
 (38) has  extensively investigated a  trapezoidal  flume with a  flat floor
 throughout  the flume that  conforms  to  the general  slope  of the channel.
Other  designs,  such as  the one reported  by Gwinn (39), have^the floor
 sloping slightly  towards  the center  to form a.very  shallow "V".
                                     86

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          R=W
                  FLOOR  ON
                  3%  SLOPE
                     \STILLING  WELL
                      INTAKE: HOLE  OR  SLOT
 ZERO DATUM'

         SIDE VIEW
 FREE  FALL
a.  Original San Dimas  Flume
            PLAN
STILLING WELL INTAKE:
HOLE OR SLOT
                FLOOR ON
                3% SLOPE
      SIDE VIEW
                   ZERO DATUM
b.  Modified San Dimas Flume
     Figure 23.  San Dimas Flumes
                   87

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TABLE 19.  SAN DIMAS FLUME EVALUATION
Evaluation Parameter
1
2
3
4

5

6
7
8
9
10
11
12
*
13
14
15
16
17
18
19
20
21
22
23
24
25
Range
Accuracy
Flow Effects on Accuracy
Gravity & Pressurized Flow
Operati on
Submergence or Backwater
Effects
Effect of Solids Movement
Flow Obstruction
Head Loss
Manhole Operation
Power Requirements
Site Requirements
Installation Restrictions
or Limitations
Simplicity and Reliability
Unattended Operation
Maintenance Requirements
Adverse Ambient Effects
Submersion Proof
Ruggedness
Self Contained
Precal ibration
Ease of Calibration
Maintenance of Calibration
Adaptabi 1 i ty
Cost
Portability
Scale
D Poor
D Poor
D High
63 No

D High

D High
D High
D High
D Poor
D High
D High
D High

D Poor
D No
D High
D High
D No
D Poor
D No
D No
D Poor
D Poor
D Poor
D High
63 No
D Fair 63 Good
63 Fair D Good
D Moderate 63 Slight
D Yes

D Moderate 63 Low

D Moderate 63 Sli'ght
D Moderate 63 Slight
D Medium 63 Low
53 Fair D Good
D Medium 63 Low
D Moderate 63 Slight
D Moderate 63 Slight

D Fair 63 Good
53 Yes
D Medium 63 Low
63 Moderate Q Slight
D Yes
D Fair 63 Good
63 Yes
63 Yes
D Fair 63 Good
D Fair 53 Good
D Fair D Good
D Medium 63 Low
D Yes
                   88

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89

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Sizes and maximum discharge capacities for trapezoidal flumes vary
widely.  Some are capable of measuring flows under 28 £/s (1 cfs),
while one of the largest known to the writers (located near Tombstone,
Arizona) has a throat width of 36.6m (120 ft) and is rated to a maximum
discharge of 736,000 £/s (26,000 cfs).

When the throat width is reduced to zero, such flumes are more properly
termed triangular flumes.  Distinct advantages of a triangular flume
are its ability to measure accurately over a wide range of flows and
its high tolerance for submergence.  Some designs can tolerate sub-
mergences as high as 90%, as opposed to the 60% noted earlier for the
Parshall flume.  Trapezoidal flumes will lie between these two values
depending on their individual geometries.  Trapezoidal flumes, including
triangular, are evaluated in Table 20.

Type HS, H. and HL Flumes - The U.S. Department of Agriculture (USDA)
Soil Conservation Service has HS, H, and HL type flumes in use in many
small watersheds.  These USDA (40) flumes are illustrated in Figures  25
and 26.  It is pointed out that all dimensions are proportional  to the
total  depth  (height) of a given flume.  These flumes have the advantage
of simple construction and reasonably good accuracy over a wide  range
of flows.  A variety of sizes are available to measure flows ranging
from 0.006 l/s  (0.0002 cfs) to 3,400 £/s  (120 cfs).

These  flumes differ from the flume types  discussed earlier because they
are, in fact, more weir than flume.  They are more properly  termed open
channel flow nozzles but are included here because of historical prece-
dent.   Their design attempts to combine the sensitivity and  accuracy  of
the sharp-crested weir and the self-cleaning features of the flume.   The
result is a  compromise in both.  The  flat, unobstructed bottom allows
the passing  of  silt better than a weir.   Like  the weir, flow control  is
achieved by  discharging  through a  sharp-edged  opening.  However, the
flow is contracted gently  from the sides  only, much  like the converging
section of ordinary flumes.  The plane  of the  exit tilts backward toward
the incoming flow.  Like weirs, these flumes should  be used  in free out-
fall situations, and  the minimum head loss will  be the measured  head.
Head is measured upstream in subcritical but accelerating  flow,  and
 critical flow occurs  over the  crest  as  with an ordinary weir.

These  devices are  capable of measuring  quite wide ranges of  flow in  some
 instances.   For example,  Soil  Conservation Service rating  tables for
H flumes indicate  possible ranges  of 175:1 for a 0.15m (0.5  ft)  flume
 and 5633:1 for a 1.38m (4.5  ft)  flume.   Type HS, H,  and HL flumes are
 evaluated as a group  in Table 21.

 Open Flow Nozzles

 As mentioned in the discussion of Type HS, H,  and HL flumes, the open
 (channel) flow nozzle is a combination of flume and sharp-crested weir.
                                     90

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TABLE 20.  TRAPEZOIDAL FLUME EVALUATION

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
Evaluation Parameter
Range
Accuracy
Flow Effects on Accuracy
Gravity & Pressurized Flow
Operation
Submergence or Backwater
Effects
Effect of Solids Movement
- Flow Obstruction
Head Loss
Manhole Operation
Power Requirements
Site Requirements
Installation Restrictions
or Limitations
Simplicity and Reliability
Unattended Operation
Maintenance Requirements
Adverse Ambient Effects •
Submersion Proof
Ruggedness
Self Contained
Precal ibration
Ease of Calibration
Maintenance of Calibration
Adaptabi 1 i ty
Cost.
Portabil ity
Scale
D Poor D Fair 81 Good
D Poor SI Fair D Good
D High O Moderate Kl Slight
53 No D Yes
D High D Moderate 63 Low
D High D Moderate H Slight
Q High D Moderate SI Slight
DHigh D Medium SI Low
D Poor 8) Fair D Good
SO High D Medium SI Low
DHigh D Moderate 63 Slight
D High D Moderate E§ Slight
D Poor D Fair S3 Good
D No SI Yes
DHigh D Medium S3 Low
DHigh 53 Moderate D SI i ght
D No ' D Yes
D Poor D Fair 53 Good
D No SI Yes
D No .-..-. SI Yes
D Poor D Fair SI Good
D Poor D Fair SI Good
D Poor D Fair Q Good
DHigh D Medium SI Low
SI No D Yes
                 91

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a
in
o
                                                                                 a
                                                                                 t—i
                                                                                 in
                                                                                 LU

                                                                                 _J

                                                                                 LU
                                                                                              (N
                                                                                               60
                                                                                               •H
                                              92

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               HS  FLUME
              H FLUME
              HL FLUME
Figure 26.  Isometric View of Type HS, H,  and  HL Flumes
                            93

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TABLE 21.  TYPE HS, H, AND HL FLUME EVALUATION
Evaluation Parameter
1
2
3
4

5

6
7
8
9
10
11
12

13
14
15
16
17
18
19
20
21
22
23
24
25
Range
Accuracy
Flow Effects on Accuracy
Gravity & Pressurized Flow
Operation
Submergence or Backwater
Effects
Effect of Solids Movement
Flow Obstruction
Head Loss
Manhole Operation
Power Requirements
Site Requirements
Installation Restrictions
or Limitations
Simplicity and Reliability
Unattended Operation
Maintenance Requirements
Adverse Ambient Effects
Submersion Proof
Ruggedness
Self Contained .
Precal ibration
Ease of Calibration
Maintenance of Calibration
Adaptabi 1 i ty
Cost
Portabi 1 i ty
Scale
D Poor D Fair & Good
n Poor 63 Fair D Good
D High D Moderate 81 Slight
8 No D Yes

63 High D Moderate D Low

QHigh 63 Moderate D SI ight
D High D Moderate H Slight
63 High D Medium D Low
D Poor D Fair 53 Good
D High D Medium 63 Low
DHigh 63 Moderate D Slight
D High B Moderate D Slight

D Poor D Fair 63 Good
D No 63 Yes
D High 53 Medium D Low
D High 63 Moderate D Slight
D No D Yes
D Poor D Fair 63 Good
D No 63 Yes
D No 63 Yes
D Poor DFair 63 Good
D Poor 63 Fair D Good
D Poor D Fair D Good
DHigh D Medium 63 Low
D No 53 Yes

-------
 Unlike the conventional weir, it can handle suspended solids rather ef-
 fectively, as a self-scouring action exists, and relatively large solids
 will pass without clogging.  Use of open flow nozzles for heavy sludge
 however, is not recommended unless calibration is for such use.  Any de-
 position will alter the contour of the nozzle and, hence, its flow
 characteristics.  For this reason the top of the nozzle is open in most
 designs to allow for ready inspection and cleaning.

 Conversely, the open flow nozzle does not have the good head recovery
 characteristics of the flume.  The loss of head through the device will
 be at least one pipe diameter.  Open flow nozzles are designed to be
 attached to the end of a conduit flowing partially full and must dis-
 charge to a free fall.

 As with all head-area meters, the design is such that a predetermined
 relationship exists between the depth of the liquid within the nozzle
 and the rate of flow.   In one design (the Kennison nozzle),  the cross-
 section is shaped so that this relationship is  linear.   In another de-
 sign (the parabolic nozzle),  the relationship is a parabola so that each
 unit increase in flow produces a smaller incremental increase in head.
 ine discharge profiles of these two  nozzles .are depicted in Figure 27.

 Open flow nozzles  are  factory calibrated and offer reasonable accuracy
 (often better than ±5% of the reading)  even under  rather severe field
 conditions.   Standard  sizes are available from  15  to 91  cm  (6 to  36  in )
 in diameter,  with  maximum capacities up  to  850 Us  (30 cfs).   These  de-
 vices are capable  of ranges of 20:1  or better and,  for a given site,
 will exceed the  range  of  either  a Parshall  flume or  a sharp-crested
 weir.  Parabolic nozzle lengths  are roughly four times the diameter,
.while Kennison nozzle  lengths  are twice  the diameter.  Open flow noz-
 zoles require a length of  straight pipe  immediately  upstream  of the
 nozzle, and the slope of  the approach pipe must not  exceed certain lim-
 its^ (depending upon nozzle size  and profile) or else  the  calibration
 will be in error.  Open flow nozzles are evaluated in Table 22.

 The open flow nozzles discussed above were characterized by a cross-
 sectional profile shaped to give a better depth-discharge relationship
 than the ordinary circular pipe cross-section.  The latter can be used
 for^indicating flow, but high accuracies are not normally achieved,
 ±10% or worse being typical.  The method, developed by Vanleer (41), is
 commonly referred to as the California pipe method, and uses as the pri-
mary device a straight, level  (zero slope) section of pipe at least six
 diameters in length (see Figure 28a).  The pipe, which cannot be flowing
 full, must be located so that there is free fall for the liquid at its
exit, i.e., it must discharge freely into air.   Also the velocity of ap-
proach must be at a minimum.   The measurement taken is the distance from
the crown of the pipe to the free water surface  at the exit.   An
empirically-developed rating formula (or set of  tables)  is used, knowing
                                   95

-------
a.  Linear  (Kennison) Nozzle Profile  (Q «  H)
b.   Parabolic Nozzle  Profile (Q « H  )
    Figure 27.  Open Flow Nozzle Discharge Profiles
                       96

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              TABLE 22.  OPEN FLOW NOZZLE EVALUATION
      Evaluation Parameter
1
2
3
4
  8
  9
 10
 11
 12

 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
24
25
 Range
 Accuracy
 Flow Effects on Accuracy
 Gravity & Pressurized  Flow
 Operation
 Submergence or Backwater
 Effects
 Effect of Solids Movement
- Flow Obstruction
 Head Loss
 Manhole Operation
 Power Requirements
 Site Requirements
 Installation  Restrictions
 or  Limitations
 Simplicity  and  Reliability
 Unattended  Operation
Maintenance Requirements
Adverse Ambient  Effects
Submersion Proof
Ruggedness
Self  Contained
Precalibration
Ease  of Calibration
Maintenance of Calibration
Adaptability
Cost
Portability
                                 D Poor
                                 D Poor
                                 D High
                                 81 No
 D High
 D High
 8! High
 D Ppor
 D High
 D High
 D High

 D Poor
 D No
 D High
 D High
 O No
 D Poor
 D N.o
 D No
 D Poor
 D Poor
D Poor
D High
D No
                        Good
                      D Good
          D Moderate 81 Slight
                      D Yes
                                 High   D Moderate Q L
                                                         OW
                                        8! Moderate D Slight
                                        D Moderate 81 Slight
                                        D Medium   D Low
                                        D Fair     81 Good
                                        D Medium   81 Low
                                        81 Moderate D Slight
                                        81 Moderate D Slight

                                        D Fair     gj Good
                                                   81 Yes
                                        81 Medium   D Low
                                        81 Moderate D Slight
                                       D Fair
                                       D Fair
                                       81 Fair
                                       D Fair
                                       D Medium
81 Good
53 Yes
B3 Yes
81 Good
D Good
D Good
81 Low
   Yes
                          97

-------
                         ZERO SLOPE
1_
     t	;	
               •6d  OR GREATER
      a.   CALIFORNIA  PIPE METHOD
           MID-DEPTH
                                    TO  CENTER OF
                                    STREAM
       b.   TRAJECTORY METHODS
   Figure 28.  California Pipe and Trajectory Methods
                        98

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                                                 diameter
 the foula Wp    K-         '  The exPerl^ntal data used to develop
 in if T7 laje   obtained on steel pipes from 7.6 to 25.4 cm (3 to
 10 in.) in diameter, but tables can be found  extending up to 0 9m f3 ft)




 consequently, will not be separately evaluated.        nozzles  a*d,

 Trajectory Methods

 The California pipe method,  although discussed under  open flow nozzles
 may also be considered as a  trajectory method.  Trajectory methods a"te'

                   *"***•  ?* T"* ^ fit in ^  ^scusSon at this
                          °f techni
-------
this seemingly simple procedure is that the velocity Profile of a £1 ow
is dependent upon many factors, and frequently a series of velocxty
measurements will be necessary in order to arrive at the average veloc-
?ty ^ss a section.  The following quotation from the USDI Bureau of
Reclamation (10) is given to illustrate some of the vagaries and methods
for toplementation!  "The. {at****, method* OJUL u*e.d to dete^ne, me.an
velocities Jin. a. vertical tine, with a. current mete*,'.

      (1 }  Two-point method.
      (2)  Stx.-tewtfa-de.pth method.

      (3)  Vertical ve£oOsity-c.ustve, method.

      (4)  Subsurface. method.
      (5)  Integration method.

      (6)  Two- tenth* method.

      (7)  Thre.e,-point method.
      (B)  Ones-point continuous method.

 The. Mo-point method consist*  of, metsurind the. velocity at 0 ^ ^ th in
 ato B of, the. de.pth £rom the. wateJi 4u/Lrfac.e, and uA^n9  the. ave/uzae o^  the,
 too mL^Sen*6.   The. accuracy obtainable. uUktiU* ytfcod "^™i
 j$i Sf JLA^aLauUd.  The, method thouM not be, aAerf Mheu th*. depth
 Jti> JieA& than 2 fcet..

 The. ^-tenths-depth method con^tA o$
 the, depth turn the. wte* AutfacA, *nd 4*
       wheJte. the. two-point method ii> not appJUaabJie..
        &ati& factory
                                                od
                                        The, method
 The.
               method c.on*O>t* o
               of, 0.5 £oot 01 mou and
mean, a* tindina the. mean vatoe
           but i& time, con&iming and c.o&tty.

  The. AutouMfux.  method invotoe* meMuMng the. velocity nem the. uateti
  l^aee and then muttiplyina it by a.  <»&<^ "**%*.
  0.95,  de.pendina on the.  depth o£ wtex., the, veto c*ty, ,and
  £L AtoSm  o* canal bed.   The.  WtifWot ^^^d
  e.Uicie.nt Unutt> the, uAe method.

  The. integration method  it> pui&med  by obAWbte
  l^caltine. by Atnoly and unitoxmty to^e^n  and
  tiwughout the. lanse, o£ wtui depth  Mo or
  not accuMte. and should be aied only fax. compasuAon*  on.

                                                 rough
                       100

-------

                               and- om-point co^nuou* method*
  For conduits flowing full and under pressure,  the velocity profile will
  wall J±£r    ^ ^T^ nUmber>  the cross- Bectlonal^Lpe,  LTSe
  wall roughness,  among other factors.   As in the case for open channel
  flow  some prior knowledge of the flow characteristics  is necesslry in
  order to  use a single velocity reading to compute discharge.

 comments in the following

 Floats
Saced £°S me?°d °f determininS flow velocity, one or more floats are
t*™f A   ™   J^V and the±r t±me to travel a measured distance is de-
termined   The simple use of surface f loats , floats immersed less than
           f,the.fiow ^epth, is the least desirable of all as they Sy
                W-       SCtS ln addition to cu"ent effects.   Since the
          Tol* 8Jrter than,the meaU velocity> a correction must be
          For reasonably smooth flows in regular conduits,  the correction

                          °'7 " °'9 deendi           w depth,
 aped
 applied.
worf fairlvwna?eS,re f °ranges» whlch float »BtIy submerged and
work fairly well in  the shallow flows found in many sewers.  Somewhat
more sophisticated are the rod floats, which consist of a square or

thaf it°wiSSft  I ^°°den); '^ r°d ±S deSlgned W±th a wei^ted end so
that it will float in a vertical position with the length of the im-
mersed portion approximately 0.9 times the depth of the flow.  The rea-
soning here is that  the velocity of a rod float which extends from
A further improvement in accuracy is known as the integrating float
method, which is discussed by Lin (43).  Here, buoyant spherL are
                                  101

-------
released from the channel floor and are displaced downstream as they
rise to the surface.  The time from the moment of release to the moment
of surfacing is measured as is the distance traveled downstream.  The
proper selection of size and specific gravity of the spheres for a par-
ticular flow depth minimizes the error caused by initial ascent accel-
eration and permits a flow measurement method that automatically
compensates for velocity distributions in a channel.  The method is
best suited for fairly low velocities.

These methods should only be used for making rough estimates and are
not well suited for many storm or combined sewer applications, espe-
cially the integrating floats.  They are evaluated in Table 23.

Tracers

In an attempt to improve upon the accuracy of float velocity methods,
many investigators  turned to the use of liquid  tracers to measure veloc-
ity.  Dye, salt, and radioactive tracer substances have been used.  In
principle, a slug of tracer is instantaneously  introduced into  the  flow
at an upstream  station, and the time of travel  to a downstream station
a known distance away is measured.  The technique should not be confused
with dilution techniques which will be discussed later.

When dyes  are used,  the  technique  is sometimes  referred to  as  the  color-
velocity method.  Potassium permanganate,  fluorescein, uranine,  sodium
 dichromate,  and rhodamine  dyes have been  commonly used.  In application,
 the downstream time should be noted when  the center of  the  mass of col-
 ored liquid passes.  Considerable  judgment is required  to determine the
 center of mass  of  the  dye  pattern  and, consequently,  the accuracy  of .
 timing is limited.   In actuality,  the peak concentration is often  used.
 In high velocity flows,  air entrained near the surface  and  spray above
 the surface can further degrade the measurement.  Also,  it  may be  un-
 certain whether the observed dyecloud velocity is the mean  velocity of
 the stream or just the velocity of the surface.  Careful use of a fluo-
 rometer can help eliminate part of the uncertainties, but high accura-
 cies should not be expected as a rule.

 A more precise method uses salt as the tracer and is oftenDeferred to
 as the Allen salt velocity method.  It is based on the fact that salt
 in solution increases the electrical conductivity of water.  In appli-
 cation, a quantity of salt solution is forced into the stream under
 pressure through quick-closing valves.  In determining the average ve-
 locity of the salt solution, two pairs of electrodes are installed in
 the stream a known distance apart.  The electrodes are energized by an
 electrical current, and the resistivity of the water path is measured.
 The greater conductivity of the salt  solution will appear as a  decrease
 in resistance and, hence, an increase in current flow.  If the  elec-
  trodes  are connected to a control  recording  galvanometer, the  graph ot
                                     102

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TABLE 23.  FLOAT VELOCITY .EVALUATION •
Evaluation Parameter
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
Range
Accuracy
Flow Effects on Accuracy
Gravity & Pressurized Flov
Operation
Submergence or Backwater
Effects
Effect of Solids Movement
- Flow Obstruction
Head Loss
Manhole Operation
Power Requi rements
Site Requirements
Installation Restrictions
or Limitations
Simplicity and Reliability
Unattended Operation
Maintenance Requirements
Adverse Ambient Effects
Submersion Proof
Ruggedness
Sel f Contained
Precal ibration
Ease of Calibration
Maintenance of Calibration
Adaptability
Cost
Portabi 1 i ty
Scale
D Poor
53 Poor
K) High
& No
D High
D High
D High
DHigh
D Poor
D High
D Hi gh
D High
D Poor
M No
D High
S High
D No
D Poor
S! No
D No
D Poor
D Poor
D Poor
D High
D No
D Fair S3 Good
D Fair rj Good ;
D Moderate D SI ight
D Yes
D Moderate §3 LOW
D Moderate SD SI ight
D Moderate US Slight
n Medium M Low
D Fai r Kl Good
D Medium 81 Low
D Moderate E3-..S1 ight
D Moderate K Slight
D Fair ^ Good .
D Yes
D Medi um K Low
D Moderate n Slight
D Yes
D Fair 63 Good
D Yes
D Yes
. D Fair D Good
D Fair Q Good
D Fair Q Good
D Medi um 8 Low
^ Yes •
               103

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current strength will have two humps that indicate the passing of the
salt slug past each pair of electrodes.  The distance on the chart be-
tween these two humps (or peaks) is a measure of the time of travel,
and from this and the electrode spacing the flow velocity can be ob-
tained.  Salt-velocity methods are more amenable to automation than
color-velocity methods.  However, this requires rather special equip-
ment not familiar to average personnel, and its use is relatively ex-
pensive.  With care, accuracies of better than ±2% can be achieved.
This method is sometimes used to calibrate other flow measurement de-
vices in place.

Radioisotopes can also be used as velocity tracers much as in the salt-
velocity method.  The sensors here are scintillation counters or geiger
counters, but the application is essentially as described above.  The
requirements for Federal licensing, expensive equipment, and highly    ^
trained personnel together with the reluctance on the part of the public
to accept deliberate introduction of radioactive substances into their
water  tend to limit the application of this technique.  Tracer velocity
methods as a group are evaluated in Table 24.

Vortex

There  are two major sub-types of vortex  meters, the  difference being in
whether vortex  rotation or vortex generation  is measured.

Vortex-Velocity - The'vortex-velocity  meter has been discussed by  Henke
 (44) and McVeigh (45).  It  is designed to be  used  in pipes  flowing full
and under pressure.   Essentially the meter  is a conduit having  a bulge
on one side.  Flow  through  the  conduit results in a  vortex pool in the
enlarged section of the conduit.  A vortex cage  located in the  pool
counts its  revolutions, which are related  to  the  flow velocity.   These
meters can be quite accurate (to ±0.5% of  the reading) in certain flows
and have a usual rangeability of around 10:1.  They are sensitive and
have very low pressure loss.  However, solids in the flow and potential
 fouling problems make the device appear generally unsuitable for sewage
 applications.   Vortex-velocity meters, are evaluated in Table 25.

 Closely related to the operating principle of the vortex-velocity meter
 is a rotorless current meter developed in Russia.  As described by
" Replogle (8):  "The. mvten. c.on&Ute o& a. tu.be. u)ht.o.h  &ha.pe.d wto a.
 Sole! siac.i-tMuLk-thape.d ovoJL tilth *» pa^JieJL tength*.  In one. at
 *£. Ifetfefct ling***, 'wwJUto* pajuMft to ***.<%* ^
 the. tu.be? A baJUL uho&e. de.n*Uy U e^uaJL to that o^the, gagzd
          Jin the. tubi.  The. mete*, to Placed In the. **MO*U> that the.
            t the. *to& cvbcM* Mi $*. ******** oj> th<> <***%*•
       In thl tube. ^ &vt-*n motion by the. xu^aou* ^o/tee tumwuttzd
         the. &lot&, and the. baU move* astound the. cto&juL oval at a
             i the. *tx.e.am veJtoc^y.  Advantage* crooned  {ox. the. meteA 
-------
TABLE 24... TRACER VELOCITY;,EVALUATION
	 	 	 — 	 —
Evaluation Parameter
1 Range
2
3
4
5
6
7
8
9
10
1 1
12
13
14
15
16
17
18
19
20
21
22
23
24

25
Accuracy
Flow Effects on Accuracy
Gravity & Pressurized Flou
Operation
Submergence or Backwater
Effects
Effect of Solids Movement
- Flow Obstruction
Head Loss
Manhole Operation
Power Requirements
Site Requirements
Installation Restrictions
o r L i m i t a t i o n s
Simplicity and Reliability
Unattended Operation
Maintenance Requirements
Adverse Ambient Effects
Submersion Proof
Ruggedness
Self Contained
Precalibration
Ease of Calibration
Maintenance of Calibration
Adaptabi 1 i ty
Cost

Portability
— j 	 	 — — : 	 __ 	
1 Scale ]
D Poor K Fair DGood
D Poor S) Fair Q Good
D High 8 Moderate D Slight
' DNo; : 81 Yes"
D High D Moderate gj LOW
D High: D Moderate 8 Slight
j * ' «
Q High D Moderate 8 Slight
DHigh D Medium & Low
D Poor D Fair 8 Good
D High 81 Medium Q Low
DHigh D Moderate 8! Sliqht
d
D High ... Q Moderate 53 Sliciht
D Poor ' & Fair Q Good
D No |g yes
D High K Medium Q Low
DHigh D Moderate ^ Slight
D No D Yes
D Poor & Fair Q Good
£1 No Q Yes
K No D Yes
D Poor D Fair Kl Good
D Poor D Fair 81 Good
D Poor D Fair D Good

81 High D Medium Q Low
D No gj Yes
               105

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          TABLE  25.  VORTEX-VELOCITY METER.EVALUATION
       Evaluation  Parameter
                                           Scale
 1   Range
 2   Accuracy
 3   Flow  Effects  on  Accuracy
 4   Gravity  & Pressurized Flow
    Operati on
    Submergence or Backwater
    Effects
 6   Effect of Solids Movement
 7  -Flow  Obstruction
 8   Head  Loss
 9   Manhole Operation
10   Power Requirements
11   Site  Requirements
12   Installation Restrictions
    or Limitations
13   Simplicity and  Reliability
14  Unattended Operation
15  Maintenance  Requirements
16  Adverse  Ambient Effects
17  Submersion Proof
18  Ruggedness
 19  Self  Contained
 20  Precalibration
 21  Ease  of  Calibration
 22  Maintenance  of  Calibration
 23  Adaptability
 24  Cost
 25  Portability
SI Poor   DFair     DGood
n Poor   63 Fair     D Good
QHigh   D Moderate H Slight
IS No                D Yes

D High   D Moderate 69 Low
53 High
63 High
DHigh
53 Poor
D High
63 High
53 High

D Poor
D No
53 H i g h
D High
D No
 63 Poor
 D No
 D No
 D Poor
 D Poor
 D Poor
 S3 High
 63 No
D Moderate D Slight
D Moderate D Slight
O Medium   53 Low
D Fair     D Good
D Med-ium   63 Low
D Moderate D Slight
D Moderate D Slight

53 Fair     D Good
           SI Yes
D Medium   D Low
D Moderate 63 Slight
           D Yes
D Fair     D Good
           SI Yes
 SI Fai r
 53 Fai r
 D Fair
 D Medi urn
D Good
D Good
D Good
D Low
D Yes
                              106

-------
 threshold values are around 0.03  to 0.06 m/s  (0 1  to n
 Turbine Meters
 The  turbine meter,  discussed by Artz  (47)  and Yard  as    «  «





Rotating-Element Meters

                                   =
                                                                     f
                                                       o   o
                       .

                                  107

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TABLE 26.  EDDY-SHEDDING METER EVALUATION
Evaluation Parameter J
1
2
3
4

5

6
7
8
9
10
11
12

13
14
15
16
17
18
19
20
21
22
23
24
25
Range
Accuracy
Flow Effects on Accuracy
Gravity & Pressurized Flow
Operation
Submergence or Backwater
Effects
Effect of Solids Movement
• Flow Obstruction
Head Loss
Manhole Operation
Power Requirements
Site Requirements
Installation Restrictions
or Limitations
Simplicity and Reliability
Unattended Operation
Maintenance Requirements
Adverse Ambient Effects
Submersion Proof
Ruggedness
Self Contained
Precal ibration
Ease of Calibration
Maintenance of Calibration
Adaptability
Cost
Portabil i ty
D Poor
fj Poor
D High
D No

D High

D High
D Hi9h
DHigh
D Poor
D High
D High
D High

D Poor
D No
D High
D High
D No
D Poor
D No
D No
D Poor
D Poor
D Poor
D High
D No
Scale
S3 Fai r
SI Fair
D Moderate


D Moderate

SI Moderate
C3 Moderate
D Medi urn
D Fair
D Medium
D Moderate
D Moderate

SI Fair

SI Medi urn
fj Moderate

SI Fair


D Fair
SI Fair
D Fair
SI Medium


D Good
D Good
SI Slight
SI Yes

SI Low

D Slight
D Slight
SI Low
SI Good
SI Low
SI Slight
SI Slight

D Good
SI Yes
D Low
SI Slight
D Yes
D Good
SI Yes,
K Yes
53 Good
D Good
D Good
D Low
SI Yes
                     108

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TABLE 27.  TURBINE METER EVALUATION
Evaluation Parameter
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
Range
Accuracy
Flow Effects on Accuracy
Gravity & Pressurized Flow
Operati on
Submergence or Backwater
Effects
Effect of Solids Movement
- Flow Obstruction
Head Loss
Manhole Operation
Power Requirements
Site Requirements
Installation Restrictions
or Limitations
Simplicity and Reliability
Unattended Operation
Maintenance Requirements
Adverse Ambient Effects
Submersion Proof
Ruggedness
Self Contained
Precal ibration
Ease of' Call brat ion
Maintenance of Calibration
Adaptabi 1 i ty
Cost
Portability
Scale
& Poor
D Poor
D High
& No
D High
81 High
B High
D High
£3 Poor
D High
•H High
D High
D Poor
D No
8 High
D High
D No
D Poor
D No
D No
D Poor
D Poor
D Poor
Bl High
S3 No
DFair DGood
H Fair Q Good
D Moderate 03 Slight
D Yes
D Moderate gj Low
D Moderate D Slight
D Moderate D Slight
HI Medium D Low
D Fair D Good
D Medium . 63 Low
D Moderate D Slight
SI Moderate D Slight
81 Fair Q Good
8) Yes
D Medium Q Low
D Moderate {g| Slight
D Yes
8) Fai r Q Good
8] Yes
B Yes
D Fair BJ Good
8! Fai r D Good
D Fair D Good
D Medium D Low
D Yes
               109

-------
Both, have proper applications with both advantages and disadvantages.
Horizontal-axis meters have found wide use in pipe lines, water mains,
and high-flow applications that require a low permanent pressure drop.
They can handle higher flow rates than volumetric (positive displace-
ment) flowmeters, but not as high as turbine meters.  Along with
vertical-axis meters, they are also used to measure open channel flows.
A thorough treatment of the use of current meters for open channel flow
measurement is given by Buchanan and Somers (49) and the USD! Bureau of
Reclamation (10).

Vertical-Axis Meters - The most common vertical-axis meters are those
with either the S-shaped (or Savonius) rotor or with a bucket wheel
made up of a number of conical or hemispherical cups.  In general, the
bearing systems in the vertical-axis meters are simpler in design, more
rugged, better protected from silty water, and consequently, easier to
maintain than those of horizontal-axis meters.  Bearing adjustment is
usually less sensitive, and their calibration at lower velocities
(where frictional effects are higher) is more stable.  Vertical-axis
meters operate in lower velocities than horizontal-axis meters, gener-
ally having lower threshold velocities of around 0.03 meters per second
(0.1 fps) or less.  Finally, a single cup rotor serves for the entire
range of velocities, and the rotor is repairable in the field without
adversely affecting the rating.

The type AA Price current meter is probably the most common type of
vertical-axis meter.  This device has a rotor 12.7 cm  (5 in.) in diam-
eter and 5 cm  (2 in.) high with six cone-shaped cups mounted on a stain-
less steel shaft.  It also has a vane to keep the rotor headed into the
flow, an electrical device to signal the number of revolutions, and pro-
visions for handling the meter.  An assembly drawing of a Price type AA
current meter is given in Figure 29.  There is also a Price type BTA
current meter which differs from the type AA only in its mounting yoke,
contact chamber, and the absence of the tailpiece.  For smaller flows
there is a pygmy meter that is similar to the Price meter but only about
two-fifths its size.  The rotational speed of the pygmy rotor is more
than twice that  of the Price meters, and consequently  its use is limited
to velocities up to 0*9 or 1.2 m/s  (3 or 4 fps).

Horizontal-axis  meters - This class of current meter is  less sensitive
to vertical velocity components than is the vertical-axis meter, which
will over-register in most such instances.  Vertical-axis meters cannot
correct for oblique  flow, whereas  some of the helical  rotors of
horizontal-axis  meters are designed to act as nearly perfect cosine
meters.  The horizontal-axis  rotor disturbs  the flow  less because  of
its  axial symmetry with  flow direction.  They also  present  a clearer
view to the flow than vertical-axis meters and,  consequently,  are
slightly less  susceptible to fouling.  Bearing  friction,  especially  at
higher velocities,  is  less  than  for vertical-axis meters because bending
                                    110

-------
                            ca
                            =3
                            n:
           UJ  LU  1—  H-I
           UJ  UJ  =>  CC
           3C  =  Z  «I
           33      UJ
          •  I  • .1   'CO  CO
           I-  1-  Z
       f- -Ul  Ul  i-l

       <  CJ  O
                                    et:
                                    O
                                        1—  I—   Ul  »-i  UJ
                                    o  o  o   a.  or
                                «S
                        co  a  o:
                                    a.  o.  a.
                                            o
                                            rs
                                            co
                                    i—  r—  r—  i—  CMCNJ
a:

Cu

LL.
O

I-
to
                   a:
                   LU
                   CO
                            CO

                            S
                  O  CO
                  d_  O
                       o.
                  CO
                  Z  CD

                  d  I-l
                  z  a
                  i-«  z  •
                  CO  I-l
                       CO

                  CJ  I—
                  <  o
                  I—  f
                  Z  1— CH  CO
                  o  z   CD  I— 1—
«c
or
CJ
                   •a:
                   o
                                                                         4-1
                                                  4-1

                                                  g
                                                  !-l

                                                  S-
                                                  
-------
moments on the shaft are eliminated.  Finally, although the horizontal-
axis meter has a higher velocity threshold of around 0.08 m/s (0.25 fps) ,
it, is capable of measuring higher flow velocities, with some designs
capable of measuring in excess of 9 m/s (30 fps).

The types of horizontal-axis meters in common use today are the Ott,
Neyrpic (Dumas), Haskell, and Hoff.  The Ott meter was developed in
Germany, the Neyrpic meter in France, and the Haskell and Hoff in the
United States.  All are precision instruments that can cover a wide
range of flow velocities by using propellers with a variety of screw
pitches.

Townsend and Blust (50) give a comparison of stream velocity meters, and
the reader who is further interested is referred to their discussion.
No rotating-element current meter is ideal for any extended period of
unattended operation, but they can be used to give excellent results in
the hands of a skilled operator.  Generally they are inexpensive, simple
in design, and rugged in construction.  A major shortcoming of all
rotating-element current meters is  that their accuracy is so closely
coupled with the operator.  In general, it requires much experience and
great care to select gaging sites and apply techniques in such a way as
to obtain results that approach the basic accuracy of the instrument
itself  (often ±1%).  Typically, it  is difficult to achieve better than
±2 or 3% accuracy in the field.  Carter and Anderson  (51) and Smoot and
Novak  (52) discuss accuracy of current meter measurements further.
Their obstruction to the flow and susceptibility  to fouling limit their
use in storm and combined sewers.   Rotating-element velocity meters are
evaluated in Table 28.

Other Devices

Other  devices  are available  to measure  the velocity of open  channel flow
at  a point within the  stream.  They include pitot tube,  electromagnetxc,
venturi,  thermal, optical» and other fundamental  principles.  They  are
discussed in  the  subsections of  this report  that  address their particu-
lar principles of operation,  and will not be  covered  again here.   In
 this  use (as  current meters)  they  all require attended operation.
Otherwise they function as  described in their individual discussions.

FORCE-DISPLACEMENT

 This  class of flowmeters is  related to  the variable area class  discussed
 earlier in that both operate by a force due to the flow displacing an
 obstruction (primary element) that is immersed in the fluid.   In effect,
 the drag of the obstruction is being measured, and this is related to
 the square of the fluid velocity,  among other parameters which include
 the drag coefficient.   Being proportional to the velocity squared means
 that force-displacement meters will tend to be insensitive at very low
                                    112

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TABLE 28.  ROTATING-ELEMENT METER EVALUATION

1
2
3
4

5

6
7
8
9
10
11
12

13
14
15
16
17
18
19
20
21
22
23
24
25
Evaluation Parameter
Range
Accuracy
Flow Effects on Accuracy
Gravity & Pressurized Flow
Operation
Submergence or Backwater
Effects
Effect of Solids Movement
- Flow Obstruction
Head Loss
Manhole Operation
Power Requirements
Site Requirements
Installation Restrictions
or Li mi tat ions
Simplicity and Reliability
Unattended Operation
Maintenance Requirements
Adverse Ambient Effects
Submersion Proof
Ruggedness
Self Contained
Precal i brat ion
Ease of Calibration
Maintenance of Calibration
Adaptability
Cost
Portability
Scale
D Poor B Fair D'Good
D Poor SI Fair Q Good
DHigh D Moderate K) Slight
D No 53 VP<;
lUl 'ICO
D High D Moderate ® Low

S3 High Q Moderate D Slight
QHigh S3 Moderate D Slight
D Hi.gh D Medium gj Low
D Poor SI Fai r D Good
DHigh D Medium SI Low
D High D Moderate SI Slight
D High D Moderate 53 Slight

D Poor D Fair SI Good
K No D Yes
81 High . D Medium D Low
SI High D Moderate D Slight
0 No D Yes
D Poor DFair H Good
SI No n Yes
D No SI Yes
D Poor D Fair SI Good
D Poor D Fair SJ Good
D Poor D Fair Q Good
DHigh D Medium SI Low
D No SI Yes
                   113

-------
velocities.  The dependency on drag coefficient means that calibration
will shift if the primary element becomes fouled by buildup or debris.
The secondary device measures the displacement of the primary element
and converts this into velocity or actual discharge.

Vane Meters

The vane meter is simply a vane hinged along either a vertical or hori-
zontal axis and placed in the flow (Figure 30).  The flowing fluid pro-
duces an angular displacement which is related to velocity and read by
the secondary element.

The vertical-axis vane meter is one of the most common.  As indicated in
Figure 30a, the vane may be quite short as compared with the flow depth
or, for flows whose levels do not change greatly, the vane may extend
over almost the entire flow depth in an attempt to average the velocity.
The advantages of the vertical axis arrangement are that the counter-
balancing weight can be easily changed to alter flow ranges; it can be
made to integrate velocities over a great portion of the vertical; and
its mechanical output can be recorded and indicated visually.  Its dis-
advantages include its tendency to collect debris; the high degree of
bearing friction  (resulting from its typically heavy weight) that adds
to the low flow insensitivity problem of this  class; and the fact that
removal for service  or repair is difficult.

The horizontal-axis  vane meter  (see Figure 30b) overcomes many of the
disadvantages  of  the vertical-axis type.  Among its  advantages are the
ease  of changing  the weight  at  the bottom in order  to  change ranges;
its capability for being  installed totally submerged to avoid  fouling
by floating  debris;  its  light weight  and simplified design to  reduce
bearing friction;  and the fact  that  its  output is usually  electrical.
 On the other hand,  despite its  relatively  small size and weight,  it  may
not be convenient for some installations,  and there is no visual readout
 of deflection.  Both types of vane meters will be affected by wind  on
 the exposed portion of the vane.

 Robinson (53) has described a somewhat different form of  the horizontal-
 axis vane meter that is sometimes referred to as the pendvane meter.  It
 is designed for use in open channel flow,  usually for small channels
 less than 0.9m (3 ft) deep and 1.8m (6 ft)  wide.   In the pendvane meter,
 the vane is shaped to match a particular channel cross-section so that
 its displacement is the same for a particular discharge rate irrespec-
 tive of the velocity profile (within certain specified depth limits).
 Thus the pendvane meter indicates discharge rate directly.  Errors of
 ±10% are possible, and flow range is low.

 Two percent might be considered an accuracy limit for vane meters and
 accuracies of ±5% or more should be considered more typical.  For a
                                    114

-------
   ROTATION AXIS         DOTATION  AXIS
       VANE
CHANNEL  BOTTOM-

HE:
1 — *-* v — i

u
                                                             ROTATION
                                                             	AXIS
                         JL
                               WATER SURFACE
                          VANE
(a)   Vertical Axis Meters
                  Figure 30.   Vane Meters
                                              (b)  Horizontal  Axis
                                                  Meter
                              115

-------
given weight (i.e., range setting), 5:1 or so should be considered a
typical flow range that these devices can handle.  Vane meters are
evaluated in Table 29.

Hydrometric Pendulum

The hydrometric pendulum is sometimes used in open channels as a current
meter.  In its most elemental form, it consists of a ball (heavier than
the fluid) suspended by a string (or light cable).  The angular deflec-
tion of the ball and string is proportional to the flow velocity in the
vicinity of the ball.  Accuracies are poor because stream fluctuations
make determination of the deflection angle difficult.  These are partly
due to the vortex shedding phenomenon discussed earlier.  Also, there is
usually no method for recording the output, and the device must be man-
ually operated.  Accuracy is further degraded by the complex and some-
what uncertain corrections for drag on the line that are required.
Drag on the line is increased greatly by floating debris, such as moss
or grass, catching on it.  Good features are that the drag element can
be very easily changed to alter the ranges, and the line can easily be
lengthened or shortened to measure velocity at various depths.  The hy-
drometric pendulum is evaluated in Table 30.

Target Meter

The  target meter,  discussed by Stapler  (54), is a more sophisticated
force-displacement device for measuring flows.  The primary element
 (or  target) is shaped similarly to the  sharp-edged annular orifice.   It
mounts on a support  that passes through the  conduit wall via  a  sealed,
flexible closure,  and the displacement  of  the primary  device  is meas-
ured by a strain gage or some other  suitable displacement measuring
secondary device (Figure 31).  This  meter  has relatively high accura-
cies,, approaching those of  the orifice meter under  certain conditions.

 Strictly  speaking, although the target meter is  a point velocity  meas-
uring device,  the point may be rather large  so that an integrating ef-
 fect is achieved.   Replogle (55)  reports  that  analytical and  experimental
 studies have  indicated that target meters can be designed  for open chan-
 nels of  any cross-sectional shape and can indicate discharge  rate di-
 rectly to better than ±3%,  independent of flow depth.   Such meters are
 limited  in discharge measurement  primarily by the ability  to  predict
 the general type of velocity profile existing in the flow.  Typical
 ranges are around 5:1.  They do  not appear especially suitable for use
 in flows containing suspended material such as sewage.  Target meters
 are evaluated in Table 31.

 Other

 Brief mention will be made here of a few other force-displacement type
 flowmeters.  They do not appear well suited for storm or combined sewer
 flow measurement at this time, but are included since special adapta-
 tions may be possible in some situations.
                                     116

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TABLE 29.  VANE DEFLECTION METER EVALUATION
Evaluation Parameter
1
2
3
4

5

6
7
8
9
10
11
12

13
14
15
16
17
18
19
20
21
22
23
24
25
Range
Accuracy
Flow Effects on Accuracy
Gravity & Pressurized Flow
Operation
Submergence or Backwater
Effects
Effect of Solids Movement
-Flow Obstruction
Head Loss
Manhole Operation
Power Requirements
Site Requirements
Installation Restrictions
or Limitations
Simplicity and Reliability
Unattended Operation
Maintenance Requirements
Adverse Ambient Effects
Submersion Proof
Ruggedness
Self Contained
Precal ibration
Ease of Cal ibration
Maintenance of Calibration
Adaptabi li ty
Cost
Portability
Scale
53 Poor
Q Poor
D High
SI No

D High

D High
& High
DHigh
D Poor
D High
D-High
D High

Q Poor
D No
D High
D High
D No
D Poor
D No
D No
D Poor
D Poor
D Poor
D High
Si No
D Fair DGood
SI Fair Q Good
D Moderate Si Slight
D Yes

D Moderate SI Lov/

SI Moderate D Slight
D Moderate D Slight
D Medi um S) Low
SI Fai r D Good
D Medi um SI Low
D Moderate SI Slight
Si Moderate D Slight

D Fair SI Good
S3 Yes
Si Medium Q Low
SI Moderate Q Slight
D Yes
D Fair SI Good
SI Yes
SI Yes
SI Fair Q Good
SI .Fair D Good
D Fair D Good
D Medium SI Low
D Yes
                     117

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TABLE 30.  HYDROMETRIC PENDULUM EVALUATION
Evaluation Parameter
1
2
3
4

5

6
7
8
9
10
11
12

13
14
15
16
17
18
19
20
21
22
23
24
25
Range
Accuracy
Flow Effects on Accuracy
Gravity & Pressurized Flow
Operation
Submergence or Backwater
Effects
Effect of Solids Movement
Flow Obstruction
Head Loss
Manhole Operation
Power Requirements
Site Requirements
Installation Restrictions
or Limitations
Simplicity and Reliability
Unattended Operation
Maintenance Requirements
Adverse Ambient Effects
Submersion Proof
Ruggedness
Self Contained
Precal ibration
Ease of Calibration
Maintenance of Calibration
Adaptabi 1 i ty
Cost
Portability
Scale
53 Poor
53 Poor
D High
53 No

D High

D High
D Hi9h
DHigh
D Poor
D High
D High
D High

D Poor
53 No
D High
53 High
D No
O Poor
63 No
D No
D Poor
D Poor
D Poor
D High
D No
D Fai r
D Fair
D Moderate


D Moderate

69 Moderate
53 Moderate
D Medi urn
D Fair
D Medium
D Moderate
D Moderate

D Fair

D Medium
n Moderate

D Fair


69 Fai r
$3 Fair
D Fair
D Medi urn

D Good
D Good
59 Slight
D Yes

63 Low

D Slight
D Slight
69 Low
53 Good
59 Low
59 Slight
59 Slight

59 Good
D Yes
53 Low
D Slight
D Yes
59 Good
D Yes
53 Yes
D Good
D Good
D Good
63 Low
53 Yes
                      118

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FLEXIBLE
CLOSURE
 FLOW
                STRAIN  GAGE
                (FORCE  TRANSDUCER)
                     LEVER ARM
                         CONDUIT
                              DISC
      Figure 31.  Target Meter
               119

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             TABLE 31.  TARGET METER EVALUATION
       Evaluation  Parameter
                                           Scale
 1   Range
 2   Accuracy
 3   Flow Effects  on Accuracy
 4   Gravity & Pressurized Flow
    Operation
    Submergence or Backwater
    Effects
 6   Effect of Solids Movement
 7  -Flow Obstruction
 8   Head Loss
 9   Manhole Operation
10   Power Requirements
11   Site Requirements
12   Installation Restrictions
    or Limitations
13   Simplicity and  Reliability
14  Unattended Operation
15  Maintenance Requirements
16  Adverse  Ambient  Effects
17  Submersion Proof
18  Ruggedness
19  Self  Contained ,
20  Precalibration
21  Ease  of  Calibration
22  Maintenance of  Calibration
23  Adaptability
24  Cost
25  Portability
53 Poor   D Fair     D Good
n Poor   81 Fair     D Good
QHigh   D Moderate 53 Slight
53 NO                D Yes

O High   D Moderate EJLow
D High
E3 High
D High
SI Poor
D High
D High
D High

D Poor
D No
81 High
D High
D No
69 Poor
D No
D No
D Poor
D Poor
D Poor
81 High
 £9 No
8! Moderate Lp Slight
D Moderate D Slight
81 Medium   D Low
D Fair     D Good
8! Medium   D Low
D Moderate 81 Slight
63 Moderate D Slight

81 Fair     Q Good
           SI Yes
D Medium   D Low
Q Moderate SI Slight
           D Yes
Q Fair     D Good
           81 Yes
           H Yes
D Fair     SI Good
SI Fair     D Good
D Fair     D Good
D Medium  D Low
           D Yes
                             120

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 The jet deflection meter is a development reported by Stanney (56) in
 which a fluid jet is directed across the flow stream towards two impact
 tubes on the opposite side.  The flow stream displaces the jet an amount
 proportional to the flow rate, thereby creating a differential pressure
 between the two impact tubes that is a linear function of the flow ve-
 locity of the measured fluid.  Like many so-called fluidic devices for
 measuring flow, it is primarily suitable for gas flows.  It has been
 used for clean water flow velocities from 0.03 to 0.3 m/s (0.1 to
 1 fps).   Accuracies of ±1% have been obtained over flow ranges of 5:1.
 The device does not appear at all suitable for dirty liquids and,
 consequently, will not be discussed further.

 The ball and tube flowmeter consists of a tube (usually transparent)
 bent through 180 degrees into some shape of an arc,  semicircular being
 the original design.   The tube is placed in a vertical plane concave
 upward,  and a ball (primary element) of density greater than the liquid
 and diameter smaller  than the tube is placed inside.   The flow creates
 drag forces on the ball, and it rises in the tube until they are bal-
 anced by the gravity  forces;  thus,  the position of the ball along the
 tube is  admeasure of  the flow rate.   The device should not be confused
 with the rbtameter which uses a taper so that the area varies as the
 float is displaced.   Of course,  ball and tube flowmeters  are only suit-
 able for pressurized  flow.   They are not obtainable  commercially (to
 the writers'  knowledge),  but  can be  easily fabricated  in  the laboratory.
 Accuracies  of around  ±2-5%  can be achieved over flow ranges'of up to
 5il.   When  maximum design flow rates have been appreciably exceeded, the
 ball will be  lost unless provision is made for capturing  it  at some
 point.

 Another  interesting force-displacement  type of flowmeter  utilizes  a var-
 iable weight  principle.   It consists  of a vertical section of pipe (us-
 ually transparent) containing  a  float of  density  slightly less than that
 of  the fluid  to be measured.  A  chain is  fastened to the bottom of the
 float.   The device operates under pressurized  flow conditions with flow
 in  the upward  direction.  As  the flow rate increases,  the  float rises
 and in so doing picks up  a larger portion of the chain, thus effectively
 varying  its weight.  The height of the  float in the tube  is a measure
 of  the flow rate.  This device is also not  commercially available to the
writers' knowledge.

 FORCE - MOMENTUM

 Force-momentum flowmeters measure the mass flow rate of the fluid as
opposed to  its volumetric flow rate.  Several instruments for which the
measured variable is directly related to mass flow will be discussed
below.  Those that add mechanical energy to the system, such as the
transverse momentum devices, generally require a constant speed drive
and rotating seals.
                                   121

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Axial Flow Mass Meter

The axial flow mass meter uses a turbine driven at constant speed to
induce a constant angular velocity to the fluid and a complementary
spring-retained rotor to measure the force required to overcome the an-
gular momentum.  The angular displacement of the retained rotor is di-
rectly related to the mass flow of the fluid.  The axial-flow,
transverse-momentum device is the most common of this type and is^avail-
able in several configurations.  They can be quite accurate (±0.5% of
reading) over ranges, typically, of 10:1.  They clearly are suited only
for pressurized flows and clean fluids.

Radial Mass Meter

This device, often referred to as a Coriolis mass flowmeter, has a pri-
mary element resembling a centrifugal pump.  The-fluid is accelerated   •
radially, and the torque required to accomplish this is proportional to
the mass flow of the fluid.  These devices have been discussed by
Halsell  (57).  They produce a pressure rise, rather than drop, and have
been successfully used with liquids, foams, and slurries.  Accuracies
of ±1% over of 10:1 range have been achieved.

Gyroscopic Mass Meter

This meter consists of a circular pipe loop, the  fluid flowing through
it constituting a gyroscope.   If a  gyroscope is rotated about a  perpen-
dicular  axis,  a torque is  created due to precession effects.  Like  the
other mass flowmeters, a constant-speed  motor  and rotating  seals are
required (in one design  the  gyro is vibrated rather than  rotated, and
flexible couplings  replace the rotating  seals).   The meter  is an unob-
structed pipe so  it is  suitable for handling  troublesome  liquids and
 flows  high in solids.  Pressure losses  are low, but external  power  is
required and the meter  is  quite expensive.   Its range and accuracy  are
 similar to the other mass  meters.

Magnus Effect Mass Meters

 The Magnus effect,  discussed by Schlitchting (46) and others,  is the
 phenomenon that produces a differential force on a body spinning in a
 flow field.   (It allows golfers to slice and baseball pitchers to throw
 curves, for example.)  The force is proportional to the fluid velocity
 and density and to the surface speed of the rotating body among other
 factors.  In the Magnus-effect mass meter, a rotating cylinder is im-
 mersed with its axis at right angles to the flowing stream.  Since the
 cross-section of the conduit and the surface speed of the cylinder are
 constant, the mass flow is a direct function of the "lift" on the cyl-
 inder, which is measured with suitable  transducers.  Again, the meter
 requires a constant speed drive and rotating seals.  The spinning cyl-
 inder poses a rather severe flow obstruction, and the device is not
 suitable for dirty flows.
                                    122

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 Force-momentum meters as a group are evaluated in Table 32.

 THERMAL

 Thermal flowmeters were originally developed for the measurement of gas
 flows but have also found application in liquid flows in recent times.
 In view of the extremely rapid response times that are achievable with
 some designs,  they have been especially useful in the study of turbu-
 lent boundary  layer structures and the like.  Fundamentally,  they all
 work on the principle that heat transferred between a body and a flow-
 ing stream is  related to the rate of flow.

 Hot Tip Meters

 When an electrically heated (bead,  wire,  film,  etc.)  is placed in a
 flowing fluid,  heat will be transferred from the element to the fluid
 at a rate that'is  a function of:   (a)  the velocity of the flow;  (b) the
 temperature, density,  viscosity,  and thermal conductivity of  the fluid;
 and (c)  the temperature,  geometry,  and properties of  the element.   If
 all but  one of the fluid^flow and element variables are kept  constant,
 the heated element is  a transducer  for measuring the  remaining variable.
 A  few typical  hot-tip  element configurations are depicted in  Figure 32.

 Two methods are used in flow measurement.   The  first  technique employs
 a  constant current passing  through  the sensing  element.   Variation in
 flow results in changed element temperature;  hence, changed resistance,
 which thereby becomes  a measure of  flow.  The major drawback  of  the
 constant  current system is  that the  frequency response  of  a sensor de-
 pends not only  on  sensor  characteristics, but also on flow characteris-
 tics.  The response  depends  on both  the thermal  capacity of the  sensor
 and  the heat transfer  coefficient between the sensor and its  environ-
 ment.  Since the sensor response varies with changes in flow  (changing
 the heat  transfer  coefficient), the  frequency compensation of  the  am-
 plifier must be readjusted whenever  the mean flow changes.

 The constant temperature  type of compensating circuitry overcomes  the
 primary disadvantage just mentioned  in the constant current system by
 using a feedback loop.  As the velocity past the sensor increases, the
 sensor will tend to cool with a resulting decrease in the resistance.
 This resistance decrease will cause  the voltage to decrease, thus chang-
 ing the input to the amplifier.  The phase of the amplifier is such that
 this decrease in voltage will cause an increase in the output of the
amplifier in order to increase the current through the sensor.  The
output of the constant temperature system is the voltage output of the
amplifier, which in turn is the voltage required to drive the necessary
current through the sensor.
                                  123

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TABLE 32.  FORCE-MOMENTUM METER EVALUATION
Evaluation Parameter
1
2
3
4

5

6
7
8
9
10
11
12

13
14
15
16
17
18
19
20
21
22
23
24
25
Range
Accuracy
Flow Effects on Accuracy
Gravity & Pressurized Flow
Operation
Submergence or Backwater
Effects
Effect of Solids Movement
Flow Obstruction
Head Loss
Manhole Operation
Power Requirements
Site Requirements
Installation Restrictions
or Limitations
Simplicity and Reliability
Unattended Operation
Maintenance Requirements
Adverse Ambient Effects
Submersion Proof
Ruggedness
Self Contained
Precal ibration
Ease of Calibration
Mai-ntenance of Calibration
Adaptabi 1 i ty
Cost
Portabi 1 ity
Scale
53 Poor
Q Poor
D High
S! No

D High

D High
D High
D High
13 Poor
& High
K) High
53 High

53 Poor
D No
53 High
D High
D No
53 Poor
D No
D No
D Poor
D Poor
D Poor
58 High
E3 No
D Fair
O Fair
D Moderate


D Moderate

53 Moderate
53 Moderate
D Medi urn
D Fair
D Medium
D Moderate
D Moderate

D Fair

D Medi urn
n Moderate

D Fair


D Fair
D Fair
D Fair
D Medi urn

D Good
81 Good
SI Slight
D Yes
,?

53 Low

D Slight
D Slight
53 Low
D Good
D Low
D Slight
D Slight

D Good
53 Yes
D Low
53 Slight
D Yes
D Good
53 Yes
53 Yes
53 Good
53'Good
D Good
D Low
D Yes
                       124

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                           125

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Ling (58) introduced the hot-film probe for use in liquid flows in 1955.
Since then, a number of investigations have been carried out in liquids
with only a few being successful.  In most of these, the film was placed
away from the wall since its size can interfere with the detailed meas-
urements required in the sub-layer region.  Indeed, different configura-
tions of film probes have produced very different results within the
same experiment even for the simple case of measuring velocity profiles
in turbulent flows.  The one type of film probe that holds promise of
being applied to sewer flow is the flush-mounted probe, because the
backing material does not interfere with the flow field and has the best
chances of physical survival in the sewer environment.  Very little re-
search has been done to determine the feasibility of using flush-
mounted, hot-film sensors for quantitative measurements in water because
the electrolysis problem has only recently been solved through the use
of quartz coatings.  Runstadler, et al (59) give a very concise summary
of the factors that significantly affect the stable non-drift operation
of hot-film probes in water.  Hot-tip probes are evaluated in Table 33.

Cold-tip Meters

Harris  (60) has described a sort of inverse of the hot-tip meters.  The
operating principle of his device involves the use of a thermoelectric
cooling unit to provide a cold surface in contact with the stream flow.
The temperature of the cold surface is then, of course, a function of
stream velocity and the other factors noted in the discussion of hot-
tip devices.  This approach would offer advantages when applied to a
fluid containing dissolved gases which tend to come out of solution when
heated by a hot-tip type element.  The temperature difference between
the probe and the fluid must be even smaller than with the hot-tip de-
vices, however, because most storm and combined sewer flows are closer
to their freezing temperatures than their boiling points.  The ice for-
mations will affect calibration.  Although interesting, it is not felt
that cold-tip devices are ready, as yet, for application as sewage flow
measuring  devices.  Most of the evaluation comments of Table 33 hold for
cold-tip devices also.

Boundary Layer Meter

Laub  (61,  62) and Barlow  (63) describe a boundary  layer meter wherein
the heater and temperature measuring elements are  on  the outside of the
conduit.   With this design, only the layer of fluid immediately adja-
cent to  the inner wall of the conduit is heated.   Response times of
under a second are possible as  is  temperature compensation.  There is
no obstruction to the flow in such a design, so the meter introduces
no additional head loss.  Errors can result from changes in fluid com-
position which would change the parameters affecting  thermal devices
 (e.g.,  viscosity, specific heat, thermal  conductivity, etc.).  The de-
vice would appear to overcome many of the other objectionable  features
of  the  hot-tip designs, however.   Good ranges  (50:1)  and accuracies
 (±1%) are  achievable under ideal circumstances, but should not be ex-
pected  in  a  sewage measurement  application.
                                   126

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TABLE 33.  HOT-TIP METER EVALUATION
Evaluation Parameter
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
1,8
19
20
21
22
23
24
25
Range
•-Accuracy
Flow Effects on Accuracy
Gravity & Pressurized Flow
Operation
Submergence or Backwater
Effects
Effect of Solids Movement
-Flow Obstruction
Head Loss
Manhole Operation
Power Requirements
Site Requirements
Installation Restrictions
or Limitations
Simplicity and Reliability
Unattended Operation
Maintenance Requirements
Adverse Ambient Effects
Submersion Proof
Ruggedness
Self Contained
Precal i brati on
Ease of Calibration
Maintenance of Calibration
Adaptabi 1 i ty
Cost
Portability
Scale .
D Poor
S3 Poor
D High
D-No
D High
S High
D High
D High
D Poor
D High
D High
D High
D Poor
D No
SI.High
D High
D No
D Poor
D No
D No
D Poor
D Poor
D Poor
S) High
SI No
^ Fair D Good -
D Fair D Good
D Moderate SI SI ight
53 Yes
D Moderate E3 Low
$
D Moderate D Slight
SI Moderate Q Slight
D Medi urn S3 Low
Si Fair D Good
S) Medium D Low
SI Moderate D Slight
IE Moderate D Slight
SI Fair Q Good
SI Yes ,
D Medi urn D Low
SI Moderate Q SI ight
D Yes
SI Fair D Good
53 Yes
SI Yes
D Fai r SI Good
SI Fair D Good
D Fair D Good
D Medi urn Q Low
D Yes
                  127

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As in the case of thermal probes, it is possible to locate a number of
sensors along the vertical  (here, around the periphery of the conduit
if. round) and thereby measure depth as well as velocity under open chan-
nel flow conditions.  Such designs have recently become available, but
experience with them is limited as yet.

Eshleman and Blase  (64) describe a related device which is more properly
termed a thermal time-of-flight flowmeter.  It is actually a tracer
technique, but here the tracer is energy in the form of heat.  A heater
element is used to introduce a slug o.f heat (a thermal wave) into the
boundary layer flow.  Temperature compensated thermistors, located a
known distance downstream, were used to detect the heat pulse (extremely
complex electronics were required) and its time of flight was deter-
mined.  This velocity could be related, through calibration, to mean
flow velocity, but accuracy and repeatibility were poor in the device
as designed.  Thermal boundary layer meters are evaluated in Table 34.

ELECTROMAGNETIC

In 1839, Michael Faraday attempted to measure flow by lowering large
electrodes into the Thames River near the Waterloo bridge.  This experi-
ment did not succeed.  Faraday's Law states that if a conductor/'^(in this
case the flowing fluid) is passed through a magnetic field, a voltage
will be inducted across the conductor at right angles to both the lines
of flux and the direction of motion and will be proportional to the
velocity of the conductor and the strength of the magnetic field.

Today, there are a number of successful designs of electromagnetic flow-
meters, all based upon Faraday's Law.  All share the same fundamental
components, but they differ in their design of implementation,,ranging
from meters for measuring pressurized flow in pipes to point velocity
sensors.  Their earliest successful adaptations were in sea-water ap-
plications such as oceanographic current meters and logs for indicating
ships' speed.  When applied to a pipe flowmeter, the fundamental com-
ponents are a piece of straight pipe, electrical coils to produce a
magnetic field perpendicular to the axis of the pipe, and a pair of
diametrically-opposed electrodes orthogonal to the magnetic field and
the pipe axis (Figure 33).  For a velocity probe (Figure 34) the same
fundamental components are involved, but they are in a sort of "inside
out" arrangement as compared to the pipe meter.  The theory of elec-
tromagnetic flow measurement is treated in the monograph by Shercliff
(65).

There are a number of parameters of the flowing stream that must be
considered in the application of electromagnetic flowmeters.  These in-
clude:  corrosion levels, abrasion levels, possible magnetic content,
presence of entrained gases, and the ability to coat electrodes.   The
devices can tolerate low fluid conductivity, e.g., some work with dis-
tilled water, and design features can be incorporated to overcome most
problems posed by undesirable fluid characteristics.
                                  128

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TABLE 34.  THERMAL BOUNDARY LAYER METER EVALUATION
Evaluation Parameter
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
Range
Accuracy
Flow Effects on Accuracy
Gravity & Pressurized Flow
Operation
Submergence or Backwater
Effects
Effect of Solids Movement
- Fl ow Obstruction
Head Loss
Manhole Operation
Power Requirements
Site Requirements
Installation Restrictions
or Limitations
Simplicity and Reliability
Unattended Operation
Maintenance Requirements
Adverse Ambient Effects
Submersion Proof
Ruggedness
Self Contained
Precal ibration
Ease of Calibration
Maintenance of Calibration
Adaptabi 1 i ty
Cost
Portability
Scale
Q Poor
O Poor
D High
D No
D High
D High
D High
D H i g h
53. Poor
D High
D High
D High
D Poor
D No
' Q High
D High
D No
D Poor
D No
D No
D Poor
D Poor
D Poo r
53 Hi gh
& No
D Fair 8! Good
D Fair 53 Good
D Moderate 53 Slight
53 Yes
D Moderate §3 Low
D Moderate 53 Slight
D Moderate Kl Slight
D Medi urn 53 Low
D Fair D Good
53 Medi urn D Low
52 Moderate D Slight
53 Moderate D Slight
59 Fair Q Good
53 Yes
53 Medi urn D Low
D Moderate 53 Slight
D Yes
D Fair 53 Good
53 Yes
H Yes
D Fair 53 Good
D Fair 53 Good
D Fair Q Good
D Medi urn D Low
D Yes
                           129

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 FLOW
                                                ELECTRODE
                                                ASSEMBLY
                                     MAGNET  COILS
Figure 33.  Components of an Electromagnetic Pipe Flowmeter
                          130

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                                    PROBE
MAGNETIC  FIELD
   ELECTRODES
                 FLOW
                                           ELECTROMAGNET
     Figure 34.  Components of an Elec.tromagnetic
                  Velocity Probe
                          131

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An alternating polarity magnetic field (ordinarily or at near 60 Hz) is
usually generated to avoid thermoelectric effects, electro-chemical ef-
fects, and DC detection problems.  A difficulty is that the alternating
magnetic field can cause a quadrature voltage (induced noise) problem
resulting in an offset in the zero point (thus indicating flow when
there is none).  Quadrature is not constant, but can change due to elec-
trode fouling (5-10 percent output zero shifts are not uncommon when
electrode coating occurs).  The problem is reduced by using self-
cleaning electrodes and superimposing a signal equal in amplitude but
180 degrees out of phase (null adjustment).  One design uses a quadra-
ture rejection circuit to virtually eliminate zero shifts.  Although
normally used only under full pipe flow conditions, an electromagnetic
pipe flowmeter will work if the pipe is less than full (e.g., down to
about half), but an additional measurement, the fluid depth, is required
to determine flow rate.  It is also possible to mount a number of sen-
sors up the wall of the conduit to measure both velocity and depth.
Such an arrangement should be capable of measuring both open channel
and pressurized flows.  Except in attended use as a current meter, the
probe configuration, because of its necessary obstruction to the flow,
is not as desirable for measuring storm or combined sewer flows.

These devices have only relatively minor disadvantages (fouling of
electrodes in some designs, susceptibility to the presence of stray
electrical and magnetic fields) except for their relatively high power
consumption, which makes battery operation for extended periods im-
practical.  Electromagnetic flowmeters have a number of inherent ad-
vantages.  They are capable of very high accuracies (better than ±1% of
full scale) over fairly wide ranges (20:1 or more in many standard de-
signs, and higher in configurations mentioned above) and can measure
flow in either direction.  They introduce very little pressure loss,
have no moving parts, their response time is rapid (less than one sec-
ond), and output is linear.  The devices are fairly expensive, however.
Electromagnetic flowmeters are evaluated in Table 35.

ACOUSTIC

The scientific use of acoustic principles in instrumentation today has
its roots in the SOund Navigation And Ranging (SONAR) equipment devel-
oped during the Second World War.  The fundamental principles were
known, of-course, before that time, and the depth of wells has long
been measured by discharging a blank shell from a gun and using a stop-
watch to determine the echo return time.  Because most equipment in
use today operates at frequencies above the audio range, the term ul-
trasonic is used by many writers when referring to this class of de-
vices.  A very recent article by Liptak and Kaminski  (66) provides a
comprehensive survey of the field.

Acoustic meters have two classes of application in flow measurement
today; as secondary devices to continuously monitor liquid level  (or
stage) and as primary devices to measure actual flow velocity.  Common
                                   132

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TABLE 35.  ELECTROMAGNETIC FLOWMETER EVALUATION
Evaluation Parameter
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
Range
Accuracy
Flow Effects on Accuracy
Gravity & Pressurized Flow
Operation
Submergence or Backwater
Effects
Effect of Solids Movement
Flow Obstruct ion
Head Loss
Manhole Operation
Power Requirements
Site Requirements
Installation Restrictions
o r L i m i t a t i o n s
S i m p 1 i c i ty and Re 1 i a b i 1 i ty
Unattended Operation
Maintenance Requirements
Adverse Ambient Effects
Submersion Proof
Ruggedness
Self Contained
'Precal ibration
Ease of Cal ibrati on
Maintenance of Calibration
Adaptabi 1 i ty
Cost
Portability
Scale
D Poor
D Poor
D High
D No
D High
D High
D High
DHigh
£3 Poor
SI High
D High
D High
D Poor
D No
D High
D High
D No
D Poor
D No
D No
D Poor
D Poor
D Poor
m High
gl No
81 Fair D Good
D Fair S3 Good .
D Moderate £3 Slight
& Yes
D Moderate Eg Low
O Moderate K Slight
D Moderate S Slight
D Medi urn Eg Low
DFair D Good
D Med-i urn D Low
SI Moderate D Slight
S) Moderate D Slight
53 Fair D Good
S! Yes
ESI Medium Q Low
D Moderate K Slight
D Yes
Kl Fair D Good
SI Yes
83 Yes
D Fair HI Good
D Fair SI Good
D Fair D Good
D Medium D Low
D Yes
                       133

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 to both  is  the measurement of the travel  time of acoustic pulses between
 a transmitter and  receiver.  The two applications will be discussed in
 turn.

 Continuous  measurement  of liquid depths is accomplished by measuring
 the  time required  for an acoustic pulse to travel to the liquid-air in-
 terface  (where it  is reflected) and return.  The transmitter and re-
 ceiver may  be separate  physical entities  or may be combined.  There are
 two  fundamental  physical arrangements  as  depicted in Figure 35.  One
 uses air path measurement and the other uses liquid path measurement.
 Although better  short-term accuracy can be achieved with liquid path
 arrangements, for  wastewater applications the air path arrangement is
 more common since  it simplifies installation, is independent of fluid
 velocity, and avoids any contact with  the flow.

 When flow  (velocity) measurement is to be accomplished, it is not the
 velocity of sound  that  is measured but, rather, the differential veloc-
 ity  between travel in the upstream and downstream directions.  Since the
 acoustic devices are actually velocity sensors, the area and vertical
 velocity profile across the flow must  be  known.  For open-channel flow,
 the  depth must also be  determined and, understandably, manufacturers
 generally use acoustic  level sensors for  this purpose.  For widely vary-
 ing  flow depths, sensor placement is critical, and more than one pair
 of sensors  may be  required.

 As noted by Liptak and  Kaminski  (66),  acoustic flow sensing or measuring
 equipment  (like  sonar)  falls into one  of  two rather broad categories,
 passive  and active. In passive operation, the transducer does not emit
 any  acoustic energy but simply acts as a  receiver.  Flow switches  (on/
 off  state  indicators) usually sense the noise generated by the flowing
 stream and  provide indication that some predetermined threshold value
 has  been exceeded. Passive flowmeters are either immersed in the flow-
 ing  stream or, as  in the case of open-channel flow, can be located in
 air.  Fundamentally, they operate on the  ide,a that, as the flow in the
 conduit  increases, the  sound level also increases in some direct and
 repeatable  manner. Only two commercial firms offer such equipment, and
 considerable work  would be required before they could be reliably used
 in a storm or combined  sewer flow measurement application.  This is dis-
 cussed further in  Section VIII.

 There  are  a number of active acoustic  flowmeter designs available today.
 They all use at  least one pair of transducer sets  (transmitter/receiver),
 so located  that  one operates against the  direction of flow and the other
 operates with  the  flow. A  few physical arrangements are indicated in
 Figure 36.   Differences occur in the details of implementation; e.g.,
 sensor geometry, sensors immersed in the  flow or fastened to the outside
 of the conduit,  sensors projecting into the flow, flush mounted, or re-
 cessed in wells, etc.   There are also  three fundamental approaches to
 determining the  velocity of  the flow in present equipment designs -
 differential time  circuits,  total travel  time circuits, and "sing-
.around"  circuits.
                                    134

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   Separate Transmitter
   and Receiver
Combined Transmitter
and'Receiver
                    a.  Air Path Measurement
                  b.  Liquid Path Measurement
Figure 35.  Physical Arrangements of:Acoustic Depth Sensors
                               135

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   a.  WETTED
       TRANSDUCERS
                          SINGLE  PAIR
                         ^J^^
                                    FLOW
                           XX / / /
                          DOUBLE  PAIR
   b.   CLAMP-ON
       TRANSDUCERS
                                 XXXXX
FLOW
                          XXXXX
Figure 36.  Physical Arrangements of Acoustic Velocity Sensors
                           136

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 In the differential time circuit, the difference in the time of arrival
 of acoustic pulses, which are triggered simultaneously at each end of a
 diagonal path across the stream, is measured directly.  When the two
 transmitters send signals simultaneously toward each other, the flow
 of water will increase the effective speed of one and decrease that of
 the other.  The signal transmitted in the downstream direction arrives
 first, and is used to start a timer, which runs until the signal trans-
 mitted in upstream direction arrives.  This time increment is thus the
 differential between the total travel times involved and is linearly
 proportional to the fluid velocity.   The average total travel time must
 also be recorded to compensate for changes in the speed of sound of the
 fluid.  This technique is not well suited for small conduits with low
 velocities because the time differences may be on the order of
 nanoseconds.

 In the total travel time circuit, the flow velocity is computed by re-
 solving the velocity component in the flow direction as computed from
 the sequential travel times required for pulses to travel; e.g., first
 from the downstream sensor to the upstream sensor and then from the up-
 stream sensor to the downstream sensor.   Since the total travel times
 are used,  changes in the speed of sound in the fluid are automatically
 compensated for.  Errors in indicated velocity are a linear function of
 timing errors in either direction.

 The  sing-around  circuit  technique is  sometimes  referred  to as a  pulse-
 repetition frequency technique.   In  it,  cumulative measurements  of
 travel times are made by using the received pulse at the far end of  an
 acoustic path to immediately  trigger  a second pulse from the originating
 transmitter.  Arrival of the  second pulse triggers a third, and  so on.
 Either the total time required for completion of a fixed number of cy-
 cles is measured or  the  cycling rate  is  reduced to a continuous, pulse-
 repetition frequency.  Where  a single pair of transducers  is employed,
 measurements are made in one direction for a given period  and then in
 the other.   Sometimes two pairs of transducers are used  (tuned to dif-
 ferent frequencies) and operated  simultaneously.  By using the differ-
 ence in the upstream and downstream frequencies to determine the flow
 velocity,  the dependence upon the sound velocity of the fluid is
 eliminated.

 From the foregoing discussion it can be seen that one of the most im-
 portant factors  in any acoustic flow measuring device is the accurate
 measurement of time  (or its inverse,  frequency).  As noted by Smoot
 (42),  four different signal-recognition methods have been used in vari-
 ous designs on the market today - the leading-edge detection method;
 a method that utilizes the differential of the voltage time pulse train;
 the zero-crossover method; and the phase difference method.  There are
 advantages and disadvantages to each, and competing claims have been
made by proponents of one method or another.

 In summary, acoustic liquid velocity sensors have not yet reached the
 state of the art where they can be considered as simple,  off-the-shelf
                                   137

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items for wastewater flow application.  They offer many advantages, but
tend to be relatively expensive for some installations and require
highly trained technicians for their repair and maintenance.  Accura-
cies to ±0.5% of full scale are achievable, but numbers as high as ±5%
must often be considered more typical, especially for a wastewater
application.  Ranges from 20:1 to 1000:1 are possible, depending upon
design details discussed earlier.  Acoustic meters are evaluated in
Table 36.

DILUTION

The dilution method can be used to measure discharge directly without
experiencing many of the difficulties of other devices.  It can be used
in any shape of conduit flowing either partially full or under pressure
and does not involve the stream dimensions or measurement of fluid prop-
erties such as pressure, temperature, or even level.  It produces no
pressure loss, requires no drop in hydraulic grade line, offers no ob-
struction to the flow, and indicates flow rate directly by simple theo-
retical formulas.

Basically, the measurement of discharge by dilution methods depends
upon determining the degree of dilution of an added tracer solution by
the flowing water.  Spencer and Tudhope (67) have noted that dilution
methods have been known since at least 1863.  Although the earliest
tracers were brine, radioactive and fluorescent dye tracers are more
commonly used today.  They have greatly reduced the quantities of tracer
substance required and increased the accuracies achievable in many in-
stances.  For example, the fluorescent dye Rhodamine WT can be quanti-
tatively detected with an accuracy of ±1% in concentrations of less
than 10 parts per billion.
There are  two  general  techniques used in dilution  flow measurement:
the  constant-rate  injection method and the total-recovery method  (called
the  slug-injection method by  some writers).  These are depicted in Fig-
ure  37.  As  its name implies,  the constant-rate injection method  re-
quires that  the tracer solution be injected  into the  flow stream  to be
measured at  a  constant flow rate for a given period of time.  The dis-
charge is  determined by the simple formula given in Figure 37a involv-
ing  the background concentration in the stream (if any), the  tracer
concentration  and  injection rate  (both presumably  controlled  and  known),
and  the measured plateau of the concentration-time curve at the measure-
ment site.  In the total-recovery method, a  known  quantity, of the tracer
solution is  introduced into the stream in any  one  of  a number of  ways,
and  a continuous sample is removed at a uniform rate  for the  entire
time needed  for the tracer wave to pass, in  effect integrating the con-
centration-time curve.  This  integral is sometimes approximated by using
a series of  successive discrete samples.  The  discharge is simply re-
lated to the total quantity of tracer injected and the  integral of the
concentration-time curve as indicated in Figure 37b.  This latter method
requires that  the  total volume of  the tracer be accounted  for at  the
measurement  site.
                                   138

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TABLE 36.  ACOUSTIC METER EVALUATION
Evaluation Parameter
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
Range
Accuracy
Flow Effects on Accuracy
Gravity & Pressurized Flow
Operation
Submergence or Backwater
Effects
Effect of Solids Movement
- Flow Obstruction
Head Loss
Manhole Operation
Power Requirements
Site Requirements
Installation Restrictions
or Limitations
Simplicity and Reliability
Unattended Operation
Maintenance Requirements
Adverse Ambient Effects
Submersion Proof
Ruggedness
Self Contained
Precal ibration
Ease of Calibration
Maintenance of Calibration
Adaptability
Cost
Portability
Scale
D Poor
D Poor
D High
D No,
D High
D High
D High
D High
Q Poor
D High
D, Hi gh
D High
D Poor
D No
D High
D High
D No
D Poor
D No
D No
D Poor
D^Poor
D Poor
Kl High
& No
D Fai r 18 Good
D Fair .- g) Good
D Moderate 63 Slight
K Yes ,;
D Moderate gj Low
S! Moderate D Slight
D Moderate SI Slight
D Medi urn Si Low
81 Fair D Good .
SI Medium D Low
18 Moderate D Slight
SI Moderate Q Slight
SI Fair D Good
18 Yes
SI Medium Q Low
D Moderate gj Slight
D Yes
S3 Fair D Good
18 Yes
K Yes
D Fair S Good
D Fair SI Good
D Fair Q Good
D Medium Q Low
D Yes
                 139

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 Although each of these dilution methods has its advantages and limita-
 tions, they are basically similar.  A fluorometer, geiger counter, or
 some other appropriate instrument is required for determining sample
 concentration, a method of extracting a sample for analysis is needed,
 and a device to either inject tracer at a steady known rate or withdraw
 sample at a steady (but not necessarily known) rate is required.   Both
 methods require complete vertical and lateral mixing at the measurement
 site. ..Since vertical mixing usually occurs rather rapidly as compared
 to lateral mixing, the latter usually controls the distance required
 for complete mixing,  and hence,  the distance between the injection and
 measurement sites,  Cobb and Bailey (68) provided a thorough discussion
 of dye-dilution methods, in which they recommend calibration of the
 measurement reach (the length between injection point and measurement
 point) to ascertain the required mixing length and to determine rela-
 tive tracer losses (due to adsorption by pipe walls or solids for
 example).

 The effect of inflow or outflow  in the measurement reach will cause the
 point of  flow determination to shift for a  dilution-type measurement.
 Where there is no inflow or outflow in the  measurement reach,  the  mea-
 sured flow will be the flow occurring at any point in the reach.   If
 there is  inflow within the measurement reach and it is totally mixed
 with the  stream at the measurement point, the flow measured will be that
 at the measurement point,  not  the injection point.   If there  is outflow
 from the  measurement  reach but after complete mixing of  the tracer has
 occurred,  the.flow measured will be that at the  injection point, not
 the .measurement point.

 Replogle,  et  al (69)  report achieving accuracies  of  better than ±1% in
 laboratory flume measurements  using dye  dilution  techniques and
 Kilpatrick (70),  making dye-dilution discharge measurements on  the
 Laramie River under total  ice  cover,  obtained  agreement of better  than
 +2% (+0.6% in one case)  as  compared with current meter measurements.
 Shuster (71)  reports  obtaining accuracies better than ±3% using radio-
 isotopes  as a tracer.  He found  that,  in the concrete-lined trapezoidal
 channel used  in his study,  the length required for almost complete mix-
 ing was 250 to  300 times the flow depth.  Ranges of 1000:1 or better
 can be achieved.  One popular use of  the technique is to calibrate other
 primary devices.  The main disadvantages of dilution techniques are the
 cost associated with  the instrumentation required for determining  tracer
 concentrations, the lack of ruggedness in some of their designs, and the
required training for operator personnel.  The dilution method is eval-
uated in Table  37.

OTHER

There are a number of less widely used flow measurements that do not
fit well under any of the more traditional classifications discussed
so far.  They will be discussed here.
                                  141

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TABLE 37.  DILUTION METHOD EVALUATION
Evaluation Parameter
1
2
3
4

5

6
7
8
9
10
11
12

13
14
15
16
17
18
19
20
21
22
23
24
25
Range
Accuracy
Flow Effects on Accuracy
Gravity & Pressurized Flow
Operation
Submergence or Backwater
Effects
Effect o'f Solids Movement
Flow Obstruction
Head Loss
Manhole Operation
Power Requirements
Site Requirements
Installation Restrictions
or Limitations
Simplicity and Reliability
Unattended Operation
Maintenance Requirements
Adverse Ambient Effects
Submersion Proof
Ruggedness
Self Contained
Precal ibration
Ease of Calibration
Maintenance of Calibration
Adaptability
Cost
Portability
Scale
D Poor
n Poor
D High
D No

D High

D High
D High
D High
D Poor
D High
D High
D High

D Poor
D No
D High
D High
D No
D Poor
81 No
81 No
D Poor
D Poor
D Poor
£) High
D No
D Fair
D Fair
SI Moderate


D Moderate

D Moderate
D Moderate
D Medi urn
D Fair
8! Medi urn
D Moderate
D Moderate

81 Fair

81 Medi urn
Q Moderate

8) Fair


D Fair
D Fair
D Fair
D Medi urn

81 Good
81 Good
D Slight
81 Yes

81 Low

81 Slight
BB s 1 1 g h t
SI Low
8! Good
D Low
8! Slight
83 S 1 i g h t

D Good
81 Yes
D Low
81 Slight
D Yes
D Good
D Yes
D Yes
81 Good
81 Good
D Good
D Low
81 Yes
                    142

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 Doppler

 A fairly recent technique for measuring the velocity of flow in a
 liquid stream makes use of the doppler effect.  Such devices, called
 scatter frequency shift devices by some writers, may utilize any
 one of a number of forms of radiated energy, including ultrasonic
 wavelengths, infrared, ultraviolet, laser, etc.  They operate on
 the principle that when a beam of energy is projected into a non-
 homogeneous liquid, it is scattered by suspended particulate matter
 in the fluid, and some of it is reflected back to a receiver.  Owing
 to the doppler effect, the frequency of the return signal reflected
 from the scatterers in the  fluid differs from that of the trans-
 mitted signal provided there is a net movement of the nonhomogeneities
 with respect to the transmitter or receiver.  This frequency shift
 is directly related to the velocity of the scatterers (among other
 factors) and, if they are stationary with respect to the liquid  to
 the flow velocity itself.   The scatterers can range from solid parti-
 cles to gas bubbles,  the only requirement being that they move at
 the same velocity as  the flow transporting them.

 It is pointed out that such devices usually sense velocity only in a
 very small region (where the transmitter and receiver signals cross)
 and,  hence,  knowledge about the velocity profile  is normally necessary
 in order to infer total flow quantities.   For example,  at  acoustic
 frequencies of 5-10 MHz,  the reverberation volume is on the order
 of 0.003m (0.01 ft) in diameter.   This  has been used to advantage
 in laboratory studies  of boundary  layer development using  laser-
 doppler devices.

 Acoustic-doppler  devices have been investigated by the  U.S.  Geological
 Survey  over  a period of several years.  As  noted by Smoot  (42), their
 experience has  been less than totally successful.   Under good con-
 ditions, i.e.,  size and concentration of suspended particulate mat-
 ter,  the meter  functions very well, but when concentrations  are too
 low  (or particle sizes  too small)  or too high,  there is either
 sporadic or no  signal return.  A further limitation of such  devices
 is the need for temperature and composition compensation.  Under
 ideal conditions, Doppler meters can yield  accuracies of ±0.5% over
 ranges of 10:1 or higher.  They are expensive, however, and little
 SPP,C^±0nS data are availal>le.  Doppler meters are evaluated in
 Table 38.

Optical

The U.S. Geological Survey and the California Department of Water
Resources have developed a meter which uses optical methods to
determine surface velocities of streams; see Buchanan and Somers
 (49) or Smoot (42).  The meter is a stroboscopic device and essentially
                                 143

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TABLE 38.  DOPPLER METER EVALUATION
Evaluation Parameter
1
2
3
4

5

6
7
8
9
10
11
12

13
14
15
16
17
18
19
20
21
22
23
24
25
Range
Accuracy
Flow Effects on Accuracy
Gravity & Pressurized Flow
Operati on
Submergence or Backwater
Effects
Effect of Solids Movement
- Flow, Obstruction
Head Loss
Manhole Operation
Power Requirements
Site Requirements
Installation Restrictions
or Limitations
Simplicity and Reliability
Unattended Operation
Maintenance Requirements
Adverse Ambient Effects
Submersion Proof
Ruggedness
Self Contained
Precal ibration
Ease of Calibration
Maintenance of Calibratio
Adaptabi lity
Cost
Portabil ity
Scale
SI Poor DFair D Good
n Poor Q Fair S3 Goad
D High D Moderate Si Slight
D No 63 Yes

D High D Moderate H Low

ED High Q Moderate D SI ight
D High D Moderate 63 Slight
D High D Medium 63 Low
CD Poor S3 Fair D Good
D High S3 Medium D Low
DHigh E3 Moderate D SI ight
D High SI Moderate D Slight

D Poor SI Fair D Good
D No E9 Yes
D High SI Medium D Low
D High D Moderate SI Slight
D No D Yes
D Poor SI Fair D Good
D No 81 Yes
D No BYes
D Poor D Fair SI Good
D Poor D Fair SI Good
D Poor D Fair D Good
SI High D Medium D Low
SI No D Yes
                144

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  consists  of  a low-power  telescope,  a set  of  mirrors  on the periphery
  of  a drum, a variable-speed motor that  rotates  the drum at precisely-
  controlled speeds,  and a tachometer for determining  drum rotational
  speed.  Velocity measurements are made  from  an  observation point
  above the stream.   Light coming  from the  water  surface is reflected
  by  the mirrors into the  lens system and eyepiece.  By  adjusting the
  rotational speed of the  drum, the apparent motion of the  water sur-
  face  images  reflected by the mirrors slows down and  stops,  appearing
  as  if the surface of the water was  being  viewed while  moving along
  exactly in pace with it.  The velocity  can be determined  by knowing
  this  null   speed of rotation and the vertical  distance from the
 water surface to the optical axis of the  meter.

 The meter is a light-weight, battery-powered unit that has no parts
 in contact with the  flowing stream.   It can be used  for quite high
 velocity streams and for  flows heavily laden with debris and sedi-
 ment  (it was developed for flood use).  It is not useful for low-
 velocity,  tranquil flows, but has been used successfully to measure
 velocities ranging from 1.5 to 15.2m/s  (5 to 50 fps).  The optical
 meter is evaluated in Table 39.

 Electrostatic

 A Very recent development by Alger (72)  is the electrostatic flow
 meter.  The  concept  arose from the observation that a stream of water
 discharging  from a pipe  into  air appeared  to  possess  a surrounding
 electrical field or  charge.   Experimental  tests  have  been run using
 water as the  flowing medium.   The voltage  between  two dissimilar
 metal pipe sections  (electrically insulated from each other) was
 measured at different controlled  rates of  flow,  most  of which were
 within the laminar range.                   •

 It is well established that a potential  difference exists  between
 two  different metals immersed in  a fluid containing ions of the metals.
 This  is observed in  the experimental set-up just described when there
 is no  flow.   Increasing the flow  rate was  found  to produce an  imme-
 diate  decrease, in the voltage.  Decreasing the flow rate,  however,
 caused an  increase in the voltage which  required some time before
 it would steady out.   The voltage levels were also functions of
 certain elements of  the system geometry  (e.g., length of insulation
 between the two pipe  sections), the  type of metal pipe  sections
 (steel and copper were used), and perhaps  of the nature of  the fluid
 (e.g., conductivity)   as well.  The method  at present  requires that
 the pipe be flowing full  and under pressure.   It offers no obstruc-
 tion to the flow, head loss, etc., and could be rather inexpensive
 it it utilizes the natural elements of a fluid-pipe system.  It is
presently the subject of continuing research and cannot be considered
as fully understood or suitable for practical use at  this time.  There-
fore, no further discussion will be given.
                                  145

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TABLE 39.  OPTICAL METER EVALUATION
Evaluation Parameter
1
2
3
4

5

6
7
8
9
10
11
12

13
14
15
16
17
18
19
20
21
22
23
24
25
Range
Accuracy
Flow Effects on Accuracy
Gravity & Pressurized Flow
Operation
Submergence or Backwater
Effects
Effect of Solids Movement
Flow Obstruction
Head Loss
Manhole Operation
Power Requirements
Site Requirements
Installation Restrictions
or Limitations
Simplicity and Reliability
Unattended Operation
Maintenance Requirements
Adverse Ambient Effects
Submersion Proof
Ruggedness
Self Contained
Precal ibration
Ease of Calibration
Maintenance of Calibration
Adaptabi 1 i ty
Cost
Portabil i ty
Scale
D Poor 81 Fair DGood
SI Poor D Fair D Good
D High D Moderate 68 Slight
81 Mo D Yes

D High D Moderate 81 Low

D High D Moderate 53 Slight
QHigh D Moderate 8! Slight
DHigh D Medium S3 Low
D Poor 81 Fair D Good
D High D Medium 81 Low
DHigh D Moderate EJ Slight
D High D Moderate 53 Slight

D Poor D Fair 81 Good
81 No D Yes
D High D Medium 81 Low
8! High D Moderate D SI ight
D No D Yes
D Poor D Fair 81 Good
8! No DYes
D No B Yes
D Poor DFair 8) Good
D Poor D Fair 81 Good
D Poor D Fair D Good
D High D Medium 81 Low
D No 81 Yes
                146

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 Nuclear Resonance
 Nuclear  resonance flowmeters, as described by Replogle  (8)   exploit
 a property  of molecular nuclei.  In nuclear resonance,  the nucleus
 is disturbed by precessional motions, which have a negligible  effect
 upon molecular or chemical reactions.  Essentially, nuclear  resonance
 consists of observing the absorption of radio waves at  a frequency
 determined  by the ratio of the nuclear magnetic moment  to its  spin
 (called  the gyromagrietic ratio) and the value of an applied  magnetic
 field.   In  water molecules, it is particularly easy to  observe nuclear
 resonance since hydrogen protons provide a very strong  absorption
 signal.  Resonance is observed by using a receiver to detect the
 rf energy lost from a transmitter.   No resonance signal can  then be
 detected until the transmitter power is reduced and sufficient time
 has e34psed so that  the nuclei can relax to their normal distribution
 This /relaxation time is a characteristic of the nuclei and their
 environment and may  be used to indicate the velocity of flowing
 fluids.                                                       e
   •f       .  •

 ,fn the /somewhat  limited work that has  been done,  accuracies of ±0.5%
 of full scale have been achieved over  a 10:1 range under full pipe
 flow^onditions.  This  technique does  not  appear  suitable for storm
 or combined sewer application at this  time and, consequently, will
 not be discussed further.
Mis
    cellaneous
                 suf°^ed.thf the foregoing discussion has  exhausted
                  of physical principles or design adaptations  for
such          r.,OWS',  TherS are nUmer° US "ther^evices or  Methods
such as:  the Gibson (or water hammer) technique that requires  the

screws  wSch f ^^ " f^ ** '«""**«* **** ^ ^ersson
nn IM^ ^    require a reach of very regular channel and a track
on which the screen car can travel; Danaides devices, in which  flow

discharJ   ^ fcVhendei>th °f the 1±quid in a ^ntkner which is
that coSSt  f°U? h/^ib^ted offices; fixed measuring palisades
creating H'^ airf?^-sha.Ped vanes extending across the flow  and
creating a differential pressure that is related to discharge-  the
  °                     Palisades' in whi^ the flow is deSSned
                                   the Palis^ ^ tilting from

                                        of them
                                 147

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SECONDARY DEVICES

A, review of all of the secondary devices used in flow measurement
is outside the scope of the present writing.   There do exist   however,
a number of devices that are called flowmeters by their manufacturers
but which, in actuality, are secondary devices for measuring  stage
They must be used with some form of primary device before true flow
measurements can be made.  A brief discussion of these devices wxll
be given along generic lines.

As is the case with all secondary devices, there are three basic types
of information that can be provided, either separately or in combx-
nation   These are an indication of flow rate  (typxcal units are cf s
gpn, mgd, etc.;  such devices are sometimes referred to as indicators);
frunnfng total  of flow to the  observed moment  (typxcal unxts are

                                           =^?r  r  f
 not del with these topics, but will focus upon the method used to
 sense or measure water level or stage.

 Float-in-Well   This is probably the oldest type of secondary device
 insistence   It is applied in a stilling well connected to the  gage
 poinf of ?ne primary device (weir, flume, etc.).  The f^-in-well
 essentially consists of a float of some suitable shape (sxzed for
 "mpatiblSty with the dimensions of the well) «^*«*c£"™*
 to a wheel and counterbalanced in some fashion so that the cable
 remains taut.  As the float rises or falls with charges ^ water
 levtl  the cable rotates the wheel, which is connected exther mechan-
 ically or electronically to the readout, recorder, or whatever.
 Discharge is determined by the use of cams, electronic circuits.
 etc., that are characterized for the primary device involved.

 Float-in-Flow.   In  this type of secondary device,  the float rides
 on the  actual  surface of the flow, directly sensing its level rather
 than Indirectly  sensing it as  with a  stilling  well.  Float  shapes
 range ?rom spherical, to  scow  or  ski  shaped,  the  latter being desxgned
 rSnimiL disturbances  of the liquid  surface fouling by  trash or
  debris,  oscillations in the instrument,  etc.   The float xs  Attached
  to a hinged arm that is directly or indirectly (e.g., by  cable)  con-
  nected to the main body of the instrument.  Directly-connected designs
  should be immersion proof if they are to be used  in storm or  combxned
                                    148

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 sewers with any history of  surcharging.   In indirectly-connected  de-
 signs, where the main body  of  the instrument can be  located  above the
 high water  level,  it  heed not  necessarily be immersion proof, but this
 feature never hurts.

 Advantages  of float-in-flow devices  include:  freedom from the require-
 ment for a  stilling well and purge system;  direct  (rather  than indirect)
 sensing of  the liquid level; and  avoidance  (in some  designs) of cables,
 counterweights,  etc.,  typical  of  float-in-well devices.  Disadvantages
 include:  possible fouling  by  trash  or-debris (which can result in er-
 roneous readings or even physical damage);  broad chart records in some
 instances due to the  lack of damping of water surface oscillations
 that some stilling wells provide;  and a more limited range due to the
 restrictions on arm length  necessary at some installations.

 Bubbler.  In this  type secondary  device,  a  pressure  transducer senses
 the  back-pressure  experienced  by  a gas which is bubbled at a constant
 flow rate through  a tube anchored at an appropriate  point with respect
 to the primary device.   This back-pressure  can be translated into water
 depth and subsequently related to discharge.   Advantages include  a lack
 of moving parts  or mechanisms, a  sort of  self-cleaning action arising
 from the  gas flow, and virtually  no  obstruction to the flow.  One of
 its  main  disadvantages is that if  the exit  end base  of the bubble tube
 becomes appreciably reduced  due to build-up  of contaminants from  the
 flow,  erroneous  readings will  result even though the instrument may
 appear to be functioning normally.   Aspiration effects due to the ve-
 locity of the flow may also  present  problems.
                                                1
 Electrical.   These secondary devices make use  of some sort of change in
 electric  circuit characteristics  in  order to indicate the liquid  level.
 Most  designs utilize a probe or some similar sensor which is immersed
 in the flow  at  the gage point.  This sensor  is a part of an electrical
 circuit,  and  its behavior in the  circuit is a  function of its degree of
 immersion.   For  example, the sensor  could basically be an admittance-
 to-current transducer,  providing a measure of depth based on the  small
 current flowing  from the sensor to the grounded stream.  Changes  in any
 electrical property (capacitance,  resistance, etc.) can be used to
 sense  liquid  depth.  Advantages are  the absence of any moving parts,
 floats, cables,  stilling wells, gas  supplies, purge requirements and
 the fact  that they cannot plug and are usually unaffected by build-up
 of sludge, algae,  slime, mud, etc.   The major disadvantage is the re-
 quirement for the  sensing element  to physically be in the flow.   The
 presence  of  appreciable foam or floating oil and grease can cause er-
 rors in most designs.

 In a somewhat different design belonging to this class,  the probe is
not actually in the stream but is periodically lowered,  via a motor-
pulley-cable arrangement, until it makes contact with the water  surface,
which  completes a microampere circuit through the liquid to a ground
return.
                                   149

-------
This signal reverses the motor, raising the probe above the surface of
the liquid.  As in the case with a float, the amount of cable paid out
is the measure of stage.  Although this design does not require immer-
sion of the sensor in the flow, it does involve mechanical complexities
and moving parts not characteristic of the other electrical secondary
devices.

Acoustic.  This type of secondary device is growing in popularity as
prices decrease.  Requiring no physical contact with the liquid, they
enjoy all of the advantages listed for electronic designs.  They were
covered in the discussion of acoustic primary devices and will not be
redescribed here.  However, a few precautionary words will be given.
For applications where space is restricted as in some manholes and small
meter vaults, problems due to false echos may be encountered.  This
problem may be overcome at some sites by shielding the transducer, but
accurate readings (at low flows at least) should not be expected for
flows in round pipes or deep, narrow channels from most designs.  Also,
good results should not be expected if the surface of the flow is highly
turbulent or foam covered as the reduced return signal may not be prop-
erly detected.

DISCUSSION

The evaluation tables of the various flow measuring devices and tech-
niques are summarized in matrix form in Table 40.  It is re-emphasized
that these evaluations are made with a storm or combined sewer applica-
tion in mind and will not necessarily be applicable for other types of
flows.

Table 41 offers a different  (and even more subjective) comparison of
some of the primary devices or techniques that are currently being
used to measure storm and combined sewer discharges.  Each method is
numerically evaluated in terms of its percent of achievement of several
desirable  characteristics.  Dilution techniques as a class appear to be
the most promising of all.  In view of the current state of the art,
however, their usefulness is probably greatest as a tool for in-place
calibration of other primary devices.  They have also been extremely
useful for general survey purposes and have found some application as
an adjunct to other primary devices during periods of extreme flow such
as pressurized flow in a conduit that is normally open channel.

Acoustic open channel devices are also quite promising; but, because of
their dependency upon the velocity profile and the frequently resulting
requirement for several sets of transducers, they are presently only
justifiable for very large flows in view of the expense involved.  The
usefulness of the Parshall flume is evidenced by its extreme popularity.
The requirement for a drop in  the flow is a disadvantage, and submerged
operation may present problems at some sites.  Known uncertainties in
the headrdischarge relations  (possibly up to 5%) together with possible
geometric  deviations make calibration in place a vital necessity  if
high accuracy is required.  Palmer-Bowlus type flumes are very popular
                                   150

-------
                     TABLE  40.    FLOWMETER EVALUATION  SUMMARY
  Gravimetric-all  types
  Volumetric-all types
  Venturi Tube
  Dall Tube
  Flow Nozzle
  Orifice Plate
  Elbow Meter
  Slope Area
  Sharp-Crested Weir
  Broad-Crested Weir
  Subcritical  Flume
  Parshall Flume
  Palmer-Bowl us Flume
  Diskin Device
  Cutthroat Flume
  San Dimas Flume
  Trapezoidal  Flume
  Type HS, H S HL  Flume
  Open Flow Nozzle
  Float Velocity
  Tracer Velocity
  Vortex Velocity
  Eddy-Shedding
  Turbine Meter
  Rotating-Elemeh't Meter
  Vane Meter
  Hydrometr.ic  Pendulum
  Target Meter
  Force-Momentum
  Hot-Tip Meter
  Boundary Layer Meter
  Electromagnetic  Meter
  Acoustic Meter
  Doppler Meter
  Optical Meter
  Dilution



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-------
overall.  They can be used as portable as well as fixed devices in many
instances, are relatively inexpensive, and lean handle solids in the flow
without great difficulty.

All point velocity measuring devices have been lumped together in the
current meter category.  In the hands of a highly experienced operator,
good results can be obtained (the converse is also true, unfortunately),
and they are often used to calibrate primary devices in place or for
general survey work.  They are generally not suited for unattended op-
eration in storm and combined sewer flows, however.

Electromagnetic flowmeters show considerable promise where pressurized
flow is assured as do closed pipe acoustic devices.  Neither can be
considered portable if one requires that the acoustic sensors be
wetted, a recommended practice for most wastewater applications.

Open flow nozzles and sharp-crested weirs are often used where the re-
quired head drop is available.   Weirs will require frequent cleaning
and are best used as temporary installations for calibration purposes.
Flow tubes and Venturis are only suitable for pressurized flow sites
such as might be encountered, for example,, at the entrance to a treat-
ment plant.                                  '

Trajectory coordinate techniques, such as,the California pipe or Purdue
methods, require a pipe discharging freely into the atmosphere with
sufficient drop to allow a reasonably accurate vertical measurement to
be made, a situation not often encountered in storm or combined sewers.
Slope area methods, as explained earlier, must generally be considered
as producing estimates only and, consequently should be considered as
the choice of last resort (despite their apparent popularity).
                                  15;3

-------
                           SECTION VII

           REVIEW OF COMMERCIALLY AVAILABLE EQUIPMENT
The number of commercial firms that offer flow measuring or related
equipment in the market place today is astoundingly large.  Even when
attention is limited to devices intended for liquid flowmetering, the
number is still extremely large, probably well in excess of two hundred.
Many manufacturers offer more than one type of primary device (and- these
typically in numerous models), and when combined with secondary device
choices, the possible number is virtually overwhelming.  Thus, complete
coverage in a document of this sort is impossible.

The intent of this section is not, therefore, to provide a complete
catalog which lists all manufacturers and discusses all their offer-
ings.  Rather an attempt has been made to select a large enough sam-
pling of firms and product's and describe each of these briefly but in
enough detail to allow the reader to appreciate the actual implementa-
tion of the generic flow measurement methods discussed in Section VI.
In accomplishing this, well over 120 manufacturers were contacted
regarding product lines which might be recommended for application to
the measurement of sewer flows.  These firms ranged from very large,
well known manufacturers that have offered a wide range of flow -meas-
uring equipment for over a century to relatively small organizations
with a limited product line which has only recently been introduced.
Devices were included which either illustrated one of the generic flow
measurement methods or appeared to embody some novel or interesting
implementation or variation.  Even at that, there have undoubtedly
been omissions, and some manufacturers of applicable equipment may have
been overlooked.  For this the writers wish to apologize and urge any
firm that feels it has equipment suitable for sewer flow measurement
(or has refined or improved its products) to communicate this informa-
tion to them so that it might be included in any possible future update
of this work.

The common format that has been followed in describing the commercially
available equipment is straightforward and needs no explanation.  How-
ever, a few comments on the information presented are needed.  All in-
formation for a particular piece of equipment, including specifications,
special claims for it, etc., has been taken from material supplied by
its manufacturer in the form of descriptive brochures, specification
sheets, technical writeups, user manuals, private correspondence, etc.
It was not possible for the writers to verify or authenticate any of
this information, so it must be accepted as manufacturer's claims only.

A comment on prices must also be made.  Many manufacturers prefer  to
quote on an application basis.  In view, of  this and  the general  economic
                                   154

-------
conditions at the time of this writing (Fall 1974), prices where given
should be considered approximations and should be verified with the
particular manufacturer before using, even for general budgetary pur-
poses.  For example, one manufacturer who was contacted had just re-
ceived a 25 percent increase from his forging contractor and could not
tell what overall effect this would have on his prices; many suppliers
are quoting prices on a delivery basis; etc.  Because of this situ-
ation, attempts to obtain pricing information were curtailed; thus,
some manufacturer's products have no prices given.

All illustrations in this section were taken from photographs, bro-
chures, or other material provided by the respective manufacturers,
and deep appreciation for permission to use them in this report is
hereby acknowledged.
                                 155

-------
               ALPHABETICAL LIST OF MANUFACTURERS
                                                                  Page

American Chain and Cable Company, Inc ............    159
                                                                    •I r o
Astro Dynamics Inc'.  ................  ...    J-DJ

Badger Meter, Inc.
(Instrument Division)  ..................    165

Badger Meter, Inc.
(Precision Products Division)    ..............    173

BIF (Division of General Signal)   .............    177

Braincon Corporation   .  •  •> •' .............  :    •L8'*

Brooks Instrument Division
(Emerson Electric Company)  ................    lbb

Controlotron Corporation    .........  •  ......

Cox Instrument
(Division of Lynch Corporation)  ..............    iy°

                                                                    90?
Gushing Engineering  Inc ..........  •  .......    ^"^

Daniel Industries, Inc ..................    2°4

Drexelbrook Engineering Company  ..............    209

Eastech Incorporated   ..................

Edo Corporation         .................  •

Environmental Measurement  Systems
 (A Division  of WESMAR)  ..................    222

Epic  Inc.     ......................    224

Fischer  &"Porter Co ...................    234

 Carl  Fisher  and  Company    .................    2^6

 Flow Technology, Inc ...................

                                                                    251
 Flumet Co.    ......................

                                                                    253
 The Foxboro  Company    .....  .............
                                    156

-------
 GM Mfg.  and Instrument Corporation	  .  .  . -.  .    256

 Hinde Engineering  Company of California   	  .    259

 Howell Instruments	    263

 InterOcean Systems, Inc.	    267

 J-TEC Associates,  Inc.	  .    270

 Kahl  Scientific Instrument Corporation  	   ....    272

 F.  B.  Leopold Company	    275

 Leupold  &  Stevens, Inc.   .  .	    278

 Manning  Environmental Corporation  	  ..    282

 Martig BUB-L-AIR	      286

 MARV  TEC,  Inc.     .	    287

 Mead  Instruments Corporation		    289

 Meriam Instrument
 (Division  of the Scott & Fetzer Company)   	    291

 Metritape, Inc	    293

 Moore Products Company	    299

 Muesco,  Inc.	    3Q^

 NB Products, Inc	    303

 R. M. Nikkei Company	    308

 NUSonics, Inc.	    309

 Ocean Research Equipment,  Inc	    312

 The Permutit Company
 (Division of Sybron Corporation)    	    313

Plasti-Fab, Inc.		       321

POLCON, Inc.
 (An Affiliate of Carl  F. Buettner & Associates, Inc.)    ....    322

PORTAC
 (Min-Ell Company,  Inc.)	    325
                                  157

-------
RAMAPO Instrument Company	    331

Robertshaw Controls Company   	    335

Saratoga Systems, Inc.    	    338

Scarpa Laboratories, Inc	    342

Sigmamotor, Inc.	    345

Singer - American Meter Division    	    347

Sparling Division
(Envirotech Corporation) •  	    350

Taylor
Sybron Corporation
Taylor Instrument Process Control Division     	    353

Thermal Instrument Company  	    357

Tri-Aid Sciences, Inc.    	    36°

Universal Engineered Systems,  Inc.    	    362

Vicfcery - Simms,  Inc.    	•  •    367

Wallace - Murray Corporation
(Carolina Fiberglass Plant)   	 	  .-••    369

WESMAR Industrial Systems Division    	    370

¥estinghouse Electric Corporation     	    373
                                 158

-------
 MANUFACTURER:   AMERICAN CHAIN AND CABLE COMPANY,  INC.
                ACCO BRISTOL DIVISION
                WATERBURY,  CONNECTICUT  06720
                TELEPHONE (203) 756-4451

 PRODUCT LINE:   FLOWMETERING SYSTEM

 DESCRIPTION:

 The Bristol Series  840 L/V Monitoring System is designed  to measure the
 level and velocity  of  sewer flow in larger  (over  1m) sewer conduits.
 It  is^engineered primarily for manhole installation, can  be positioned
 at  existing manholes,  and  can be moved from one manhole to another for
 the purpose of  making  surveys of a sewage system.  The monitoring sys-
 tem,  shown in Figure A,  consists of three major subassemblies:  monitor
 assembly,  probe controls,  and a  probe operator or hoist assembly.  A
 single,  self-cleaning  probe is used for both velocity and flow level
 measurement.  It is designed to  withstand the corrosive environment of
 a sewer  system  and  the impact of heavy objects.

 The velocity of the flowing liquid is  determined  by a drag-type primary
 element  which is located within  the probe assembly.  A hermetically-
 sealed flexure  assembly is  fastened to a cylindrical "target" area and
 contains a four-arm strain  gage  bridge together with the  necessary com-
 pensating  networks.  As the moving stream impinges on the target area,
 an  impact  force is  developed which is  proportional to the square of the
 velocity of the stream.  The impact force causes  a linear deflection of
 the flexure, which  is  detected by  the  strain gage bridge.  An excita-
 tion  voltage from the  strain gage  power supply feeds the velocity
 sensor.  Calibration is such that  velocity of 0 to 3 m/s  (0 to 10 fps)
 corresponds to  an output signal  of  0 to 20 mV.  Thus, the force exerted
 on  the target.area  is  converted  to  an  electrical output signal from the
 strain gage sensor.  This millivolt signal is then amplified (in the
 Probe Controls  cabinet) to  0 to  10V which, in turn, becomes the input
 signal to  an electronic solid-state square root extractor.  The square
 root  extractor  (also in the Probe  Controls cabinet) converts the signal
 to  a  voltage signal  linear with velocity.

 The level  sensing device in  the probe ensures that the probe is always
 at  a  predetermined level of submersion in order to accurately measure
 the stream velocity .at a reference level.  It also detects the need for
 probe cleaning.   An air bubbler arrangement is used for determining
 the level  of probe submersion.  This is done by sensing the bubbler
backpressure.   The bubbler outlet hole is located at the lower end of
 the probe adjacent to the target 'area of the velocity measuring device,
 in a  position where it is not affected by the velocity  of  the flowing
liquid.  Should  debris cause clogging, the probe has the capability of
cleaning itself.  This is accomplished by using the pneumatic cylinder
                                  159

-------
Figure A
      160

-------
 to retract the probe through a tight-fitting wiper sleeve and then re-
 positioning it.  Simultaneously, a high-pressure air purge is directed
 at,the velocity target area and also through the bubbler outlet hole.
 Normally the self-cleaning cycle is acfuated at 15-minute intervals.

 SPECIFICATIONS:
 Size, Weight and Other
   Physical Facts:
 Power Requirements:


 Sewer Conduit Sizes:

 Liquid Level Ranges:

 Velocity Measurement
   Range:

 Air  Supply:

 Sensitivity:


 Typical Accuracy:


 Repeatability:


 Readout:




 Installation Hardware:

Telemetry Output.:
    Size and weight of the Monitor assembly
    can vary with the installation site
    requirements*  A typical assembly for a
    1.52m (5 ft) sewer conduit weighs ap-
    proximately 136 kg (300 Ibs.) and re-
    quires a trolley of 2.44m (8 ft) in
    length.

    120V,  60 Hz, single phase, 30 ampere
    service.

    1.22 to  6.1m (4 to 20 ft)  (standard).

    20.32  cm (8 in.)  to full conduit


    0  to 3 m/s: (0 to  10 fps)

    Included in Probe Controls cabinet.

    ±0.64  cm (1/4 in.)  change  in  liquid
    level.

    Velocity, ±5%
    Level, ±0.64  cm (1/4  in,)

    No measurable changes in velocity and
    level over a  period of one year.

   Analog-type panel meters included in
   Probe Controls cabinet.

OPTIONS

   As required.

   Two channels; one for velocity, one for
   liquid level.  Either solid-state pulse
   duration or variable frequency may be
   considered.   (Plug-in space is reserved
                                  161

-------
                                in the Probe Controls cabinet for either
                                type of telemetry circuit boards, and
                                for optional audio tone equipment.)
PRICE:
Prices are quoted at time of order based upon details of specifications-
e.g. size, construction materials, etc.

COMMENTS:

Since this unit only provides the flow depth and velocity at about
15.2 cm (6 in.) below the free surface, calibration of the site would
appear necessary in order to relate these two parameters to total dis-
charge.  The unit was not designed for smaller pipe sizes, i.e. under
1.22m (4 ft), and does not appear suitable for such applications.
                                    162

-------
MANUFACTURER:  ASTRO DYNAMICS INC.
               SECOND AVENUE
               NORTHWEST INDUSTRIAL PARK
               BURLINGTON, MASSACHUSETTS  01803
               TELEPHONE (617) 272-3900

PRODUCT LINE:  VOLUMETRIC-FLOWMETERS

DESCRIPTION:

This company has developed a somewhat unique (patent pending) volumetric
flowmeter.  Its primary element essentially consists of a positive dis-
placement (gear type) pump that is driven by a variable speed motor so
as to maintain a zero pressure drop across the flowmeter.  The secondary
element is a counter that reads pump speed which is directly related to
flow.  A simplified block diagram of the unit is shown in Figure A.
FLUID
FLOW

                           AP
                        TRANSDUCER
                                    '
                         >K

                                METERING  PUMP
H— i
^-r-1
ARTARI P
TACH
GEN



DIGITAL
INDICATOR
FLOW RATE
                         SPEED
                       D.C.  MOTOR
                       CONTROLLER
                           Figure A
                                 163

-------
The chief advantage of this approach would seem to arise from the fact
that the slip factor, which is inherent in all such types of volumetric
flowmeters, is greatly reduced with a nearly zero pressure differential.
At the present time these flowmeters have only been built in rather
small sizes, i.e., up to 577 &ph (150 gph), but this is not an inherent
limitation of the basic design.  The unit was developed to meet a re-
quirement for accuracies of ±0.2% of reading and repeatability of ±0.1%
of reading; these have apparently been met.  Ranges of up to 100:1 are
possible, but 15:1 is more typical.

Units are available with either analog  (0-10 VDC proportional to flow
rates) or digital  (pulse rate proportional to flow rate) outputs.
Digital panel meters to read totalized  flow  (counter) or flow rate
(digital voltmeter calibrated in gph) are optional at extra cost.

SPECIFICATIONS:
Characteristics
Range, Iph (gph)
Power
Dimensions (W,H,L),
era (1n)
Tubing Connections,
cm (in)
Max. System
Temperature, C (F)
Model
LFH - 1.5 (A) or (D)
0.39-5.68 (0.1-1.5)
115 VAC, 10, 60 Hz
17.8x17.8x25.4
(7"x7"xlO")
0.64 (1/4")
(150°F)
LFH - 15 (A) or (D)
3.79-56.77 - (1-15)
Same
17.8x17.8x25.4
(7"x7"xlO")
0.64 (1/4")
Same
LFM - 150 (A) or (D)
37.85-567.75
(10-150)
Same
30x30x35
(12"xl2"xl4")
0.3
1 .23 (1/2")
Same
 PRICE:  $1,000 (approx.) and up.

 COMMENTS:

 This is a very ingenious device, but its application to wastewater
 flows must be considered limited due to its small capacity and poten-
 tial problems with suspended solids, among other reasons.
                                    164

-------
 MANUFACTURER:
BADGER METER, INC.
INSTRUMENT DIVISION
4545 WEST BROWN DEER ROAD
MILWAUKEE, WISCONSIN  53223
TELEPHONE (414) 355-0400
PRODUCT LINE:
PRIMARY DEVICES - FLOW TUBES, NOZZLES, PARSHALL FLUMES

SECONDARY DEVICES - METER TRANSMITTER, ELECTRONIC RECEIVERS

DESCRIPTION:

The Water Meter Division of Badger has manufactured nutating disc type
water meters for a number of years.  However, because of the total un-
suitability of such devices for raw sewage, they will not be included
in this discussion.

Pr-imary Devices

Flow Tubes - The Instrument Division offers,  as primary elements,  the
proprietory "Lo-Loss" flow tubes.   These tubes are available in  a wide
choice of designs,  materials,  and  sizes and may find some application
in wastewater flow measurement.  Figure A shows typical "Lo-Loss"
designs.
         PLASTIC                           CAST  IRON

                           Figure A
                                165

-------
The chief advantage of the "Lo-Loss" design is its extremely low head
loss (claimed to be the lowest of•any primary element) even as compared
to a long form Venturi tube.  Unrecovered pressure loss as a percent of
differential seldom exceeds 6%, and values of 3% are quite common.  The
available models include both full flanged and insert designs.  Types
PMT and PMT-U have manual vent cleaners for measuring sewage or
slurries.  Type PMT-S is a single-tap, full-flanged model design for
sewage, sludge, or fluid high in suspended solids.  Available designs
are shown in Figure B.

Open Flow Nozzles. Parshall Flumes - Badger Meter Inc. also offers open
flow nozzles and Parshall flumes as primary devices.

Secondary Devices

Transmitter - The ML-MN transmitter  (Figure C) is a secondary device
designed for open channel flow head measurement.  As  flow varies, the
transmitter's in-stream float senses the  changing liquid level in the _
primary flow device.  Through a single link from a stainless  steel main
shaft, the float's motion is relayed directly to core which moves ver-
tically within  the transmitting coil.  The coil emits a signal voltage
in direct relation to the core position.   This signal is transmitted  to
the electronic  receiver as  discussed in  the description of  the  elec-
tronic receiver.

Advantages  of  this  device,  when  compared to float-cable instruments
which require  stilling wells,  are  reported to be  as  the following:

      •  INSTALLATION ECONOMY...Excavation and concrete pouring  for
         meter  chambers  are minimized.   Stilling well and  complex
         piping eliminated.

      •  MAINTENANCE ECONOMY..Clear water purge,  routine cleanouts,
         cables, and counter weights also eliminated.

      •  ACCURACY CHECK...A mechanical position reference is furnished
         as standard equipment to provide a quick, positive calibra-
         tion check.

      •  APPLICATION VERSATILITY...ML-MN transmitter and electronic
         receiver can be used with Badger Meter open flow nozzles,
         Parshall flumes, and weirs.  Accurate response is also
         assured with Palmer-Bowlus flumes, standing wave flumes,
         and any other device for which the head-discharge relation-
         ship has been established up to  a float travel of 0.8m
         (32 in.).
                                    166

-------
 TYPE  PMT: FULL FLANGED CAST IRON
 This cast iron tube has a bronze-lined throat in which the
 averaging annulus is accurately machined with the body.
 Stainless  steel throat   also  available.  Manual  vent
 cleaners provided  for  sewage, slurries or other fluids
 with suspended solids.
 TYPE  PMM:  PLASTIC INSERT

 the  pqlyester-fibreglass body, .tapped holding  flange,
 and  throat with internal annulus are molded as an in-
 tegral unit. Throat and mounting flange are available in
 a variety of materials. Suitable for liquids and gases up
 to 200° F. Minimum operating temperature minus 20° F.
 TYPE PMT-C: "CONTROLLER"  TUBE
 This model is  similar to Type PMT except that it  will
 accommodate a valve immediately downstream for rate-
 of-flow control. Outlet flange may be smaller than  line
 size to permit a smaller valve.  A standard increasing
 elbow or increaser is used to return to full line size.
 TYPE  PMT-S: SINGLE TAP,  FULL  FLANGED
 Designed for sewage,  sludge or fluids with suspended
 solids. This tube has single taps for the high pressure and
 for the low pressure connections. Each tap is equipped
 with manual vent cleaner to permit periodic cleaning.
TYPE  PMT-IF:  FABRICATED INSERT
Designed primarily for clear fluids,  Type PMT-IF is
available in a variety of materials to suit specific applica-
tions.  Can  be  supplied in  carbon  or stainless steel,
aluminum, chrome-moly and other metals. Pressure con-
nections are conveniently  located in  mounting  flange.
TYPE  PMT-U:  FABRICATED FULL FLANGED
This Lo-Loss tube offers wide flexibility in materials and
design. An  economical buy, particularly in the larger
sizes.  Can  be supplied  with single  or  multiple  taps.
Also available.with manual  vent cleaners for measuring
sewage or slurries.
                                              Figure  B
                                                      167

-------
    MOUNTING  BRACKET   f
(ALTERNATE  POSITION)1-^)
  (WATER-TIGHT SEAL)
      TRANSMISSION
      LEADS
         WATER-TIGHT
         SEAL
         NEOPRENE
         BOOT .
                                              MOUNTING
                                            .^BRACKET
                                             INDUCTANCE
                                             COIL

                                             CORE
                                     LINKAGE
                            SHAFT
 Figure  C
       168

-------
 Electronic Receiver - The Badger Meter Inc. 2700 Series electronic re-
 ceiver (Figure D) is connected to the transmitter (Figure C) by three
 transmission lines (Figure E), and power (110 VAC, 60 Hz) is applied
 only to the receiver.  An actuating signal or error voltage is pro-
 duced by the movement of the transmitting corerwithin its coil which
 unbalances the electrical bridge.  This signal is amplified to drive
 a two-phase, reversible servo motor which runs at a speed proportional
 to the error signal and in a direction established by the phase.   Rota-
 tion of the motor repositions the core in the receiving coil and
 reduces the error signal to zero.  As a result, the electrical bridge
 is restored to a null-balance condition.   The pen, indicator pointer,
 and_totalizer mechanisms are positioned simultaneously when the system
 is in balance; thus there is no time delay for recycling.

 Receiver  Style 2701 serves the combined functions of a recording,  in-
 dicating,  and totalizing instrument;  Style 2705 is used as a remote
 indicator only.

 As reported by Badger Meter Inc.,  the 2700  series electronic receiver
 can be used with a variety of transmitters  for the measurement  of  flow,
 level,  pressure,  or temperature.   For the convenience of the operator,
 the receiver can be located up to  5000  feet away  from the  transmitter
 without impairing calibrated accuracy (±1%  of  actual  value being meas-
 ured  over  the range specified for  the transmitter) or speed  of  response.
 A  selection of 30.5 cm  (12  in.) diameter  charts, with either 24-hour  or
 /-day rotation,  can be made from more than  500 standards available.

 SPECIFICATIONS:

jPrimary Devices

      •  The laying length of a typical "Lo-Loss" flow tube is
        roughly 2.5 times the pipe diameter.  Stock units are avail-
        able for pipe diameters ranging from 7.6 to 121.9 cm  (3 to
        48 in.), and other sizes can be obtained upon request.

      •  Bronze, carbon or stainless steel, aluminum, chrome-moly,
        and polyester-fiberglass are among the available construc-
        .tion materials.

     •  Standard accuracies of ±1% are claimed (or ±0.25% when
        laboratory calibrated).

     -  Ranges (see comparative rangeability of Figure F) of
        20:1 are common,  and even at 50:1, the meter coefficient
        deviation is only 2%.
                                  169

-------
     •COIL
 i   IhCCRE
TRANSMITTER
                    Figure D
               nov.
             60 CYCLE AC
               SUPPLY
    CALIBRATED
        CAM
 SERVO
MOTOR
                                         ELECTRONIC
                                         AMPLIFIER
                             RECEIVER
                    Figure E.
                        170

-------
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                          (RD) PIPE REYNOLDS NUMBER
                                Figure F
 Secondary Devices
 Range
 Dimens-ions,
 (W,  H, L)
 Power
 Response Time
    HL-MN Transmitter

 10:1  {20:1 available  for
 extra cost)
 25.8cra x. 25.4cm x  32.4cm
,(10-3/16in x lOin  x 12-ll/16in)

         N/A
         N/A
       2700 Series
       Receiver

          N/A
22.2cm  x  39.1cm x 48.9cm
(8-13/16in x 15-5/8in'x 19-3/16in)

110 VAC,  60 Hz
8 sec.  (0 to Full Scale)
PRICE:

Primary Devices

   "Lo-Loss"  Flow Tubes
                                        3 in.   -  $    716.00
                                       48 in.   -   11,700.00
                                      171

-------
   Open Flow Nozzles
   Parshall Flumes
 6 in.
24 in.

 3 in.
24 in.
$   640.00
  3,900.00

    280.00
  1,565.00
Secondary Devices

   ML-MN Transmitter/2700 Series
     Electronic Receiver                    $ 1,150,00

COMMENTS:

Primary Devices

Where pressurized flow is always present, the »Lo-Loss» flow tube could
prove to be a useful primary device for measuring storm or combined
sewer flows at fixed installations, if proper attention is paid to the
secondary element to avoid clogging problems.

The other primary devices offered by Badger  (open flow nozzles and
Parshall flumes) were thoroughly discussed in Section VI and will not
be commented upon further here.

Secondary Devices

The ML-MN transmitter will withstand submergence, even though it will
no longer operate because the  float is off scale.  Its 0.8-meter  ^
 (32-inch) float  travel  allows  it to be used  with many primary devices.
As with any float-in-flow secondary device,  it  suffers from the pos-
sibility of fouling (or even physical damage) from floating debris.
The  electronic sensing  system  offers advantages over  more  cumbersome
 cable and counterweight designs.
                                    172

-------
 MANUFACTURER:
 PRODUCT LINE:
 DESCRIPTION:
BADGER METER,  INC.
PRECISION PRODUCTS  DIVISION
6116 EAST 15TH STREET
TULSA, OKLAHOMA  74115
TELEPHONE (918)  836-4631

ULTRASONIC FLOWMETER;
ULTRASONIC TRANSMITTER
 Badger Meter, Inc. has entered into a cooperative agreement with Tokyo
 Keiki Seizosho Company, LTD.  of Japan to market (within the United
 States) the ultrasonic flowmeter developed by the latter company.
 There are essentially three devices offered, and sales are through the
•Precision Products Division.   A typical ultrasonic meter installation
 for full pipe flow is shown in Figure A.
                                  REMOTE
                               INDICATION
                                                         ELECTRONIC UNIT
                                                           UF-100 Unidirectional
                                                           UF-110 Bidirectional
                                                      PROBECABLES
                                                   TYPICAL INSTALLATION
                                                   OF ULTRASONIC METER
                                                  Just Strap Around the Pipe

                                                  No Installation Delays

                                                  No Interruption of Flow

                                                  No Parts in the Stream
                             Figure A
                                   173

-------
Ihe ultrasonic flowmeter uses the propagation of ultrasonic energy
across a fluid stream to determine flow velocity.  These devices are
designed for -metering raw and treated sewage and wastewaters;  also,
many industrial fluids can be metered.

Model UF-100 (Unidirectional) and UF-110 (Bidirectional) Flowmeters  -
These are complete ultrasonic flowmeters for measuring full flow in
pipe sizes of 0.3m (1 ft) and larger.  These devices employ a pair of
ultrasonic velocity probes that are strapped to the outside of the pipe
wall.  A clearance area measuring at least 1.2m (4 ft) greater than  the
pipe diameter in each dimension is required.  The device can be in-
stalled in existing as well as new construction and produces no head
loss since there is nothing inside the pipeline.  The velocity probes
utilize the "sing-around" principle* to measure average fluid velocity
within the pipe which is combined with pipe cross-sectional area to
produce an output signal (4-20 mADC) proportional to flow.  A wide
selection of 30.5 cm (12 in.) diameter charts is available with either
24-hour or 7-day rotation.  A totalizer option is also available.

Model UF 310A Flowmeter - This model is a complete open channel ultra-
sonic flowmeter that does not require the use of a weir, flume, or other
pre-rated structure.  It employs a pair of ultrasonic velocity probes
and combines their output with flow depth as measured by an ultrasonic
depth probe  (essentially the probe of Model UH 200) and channel cross-
section to produce an output signal  (4-20 mADC) proportional to flow.
The device can be installed in existing as well as new construction
and will produce little or no head loss since, at most, only the small
velocity probes need be in the flow.  As with the Models UF-100 and
UF-110, the velocity probes operate using the "sing-around" principle.
Channel shapes can be either circular, rectangular, trapezoidal, or
elliptical.  As shown in Figure B, the velocity probes are generally
mounted in, or attached to, the channel walls at about 25% of maximum
depth.  A wide selection of charts  (identical to those for Models UF-100/
110) is available, as is a totalizer option and bidirectional capability.
The  three probes, which together weigh 38.6 kg  (85 Ibs), may be located
up to 305m  (1000 ft) from the electronics box, which  is a small wall-
mounted unit weighing 68 kg  (150 Ibs).
    Each received sonic pulse triggers  the transmission of another pulse
    across the flow stream in a "sing-around"  fashion.   The number of
    such pulses occurring in a one-second period is  called the  sing-
    around frequency.
                                   174

-------
           Electronics
                              Output 4-20 MADC
                             Figure B

Model UH  200 or UH 210 Ultrasonic Flow Transmitter - This  equipment has
an output signal proportional to  level (UH 200) or flow  (UH 210) and
serves as a secondary element for level and flow indicating,  recording,
and totalizing measurements in flumes, weirs, or other open channel
primary elements.  The device employs  an ultrasonic probe  set in a com-
mon head.   The acoustic signal is transmitted to the fluid surface
(see Figure C), and the elapsed travel time for the reflected signals'
return is  converted into fluid depth.   As the level of the fluid

Iv


J2
                                    INSTALLATION
                                     A. Transmitter shall be placed at least 6" above
                                        maximum level not to exceed the Ah above
                                        maximum level (i.e. Ah min. = 6")
                                     B. Total transmission length shall not exceed
                                        10' 6"
                                     C. The horizontal plane across the face of the
                                        probe shall be level to within ± 2°
                              Figure C
                                  175

-------
surfaces changes, the TJH. 200 produces a proportional signal (4-20 mADC).
Model UH 210 incorporates a digital function generator which allows
direct and continuous conversion of the fluid level signal to any
specified depth-discharge relationship.  This can be changed in the
field to allow use with different primary elements.  A wide variety of
30.5 cm (12 in.) diameter charts is available with either 24-hour or
7-day rotation.

SPECIFICATIONS:
Characteristic
Resolution
Accuracy
Output
Analog
Time Pulse
Digital '
Probe Cable Length
Power
Dimensions
Electronics
Junction Box

Probe(s)
Height
Electronics
Junction Box
Probe
Model
UF-100 and 110
±1% of Full Scale
±1% of Full Scale

4-20 mADC Into lOOOn
3-9-3 (15 sec. period)
48V Pulse (Train Scaled)
Up to 305 meters (1000 ft)
115 VAC, 60 Hz, 3A

57 x 64 x 30 cm
(22.44x25.20x11.81 In)
8.4 x 18 x 20 cm
(3.3x7.1x7.9 In)
12.4 x 15.0 x 18.3 cm)
(4.9x5.9x7.2 1n)

54 kg (119 Ibs).
2.5 kg (6 Ibs)
16.8 kg (37 lbs)(2)
UH-200 and 210
±1/4% of Full Scale •
±2% of

Same
H/A
N/A
Same
Same

Full Scale







22.7 x 13.7 x 34.3 cm
(10-1/2x5-3/8x13-1/2 1n)
N/A

8.9 cm
6.4 cm

7.3 kg
N/A
1.8 kg


(3.5 In) D1a. X
(2.5 in) High

(16 Ibs)

(4 lbs)(l)
UF-310A
±1% of Full
±3% of Full

Same
N/A
N/A
Same
Same


N/A




N/A
38.6 kg (85
Scale
Scale














lbs)(3)
 PRICE:   Models UF-100 and TJH-110 start at about $1,000
         Model UF-310A starts at about $3,000
         Models TJH 200 and UH-210 start at about $3,000

 COMMENTS:

 These ultrasonic flow measurement devices have performed fairly well
 in their somewhat limited (up until now) use in this country.   Mod-
 els UF-310A and the UH series are especially well suited for storm and
 combined sewer flow measurement.  There have been some reports of prob-
 lems due to echos or false returns from the TJH series probes.   Some
 field workers have put a short piece of plastic pipe over the head and
 obtained improved results.
                                   176

-------
 MANUFACTURER:  BIF - A UNIT OF GENERAL SIGNAL
                1600 DIVISION ROAD
                WEST WARWICK, R.I.  02893
                TELEPHONE (401)  885-1000

 PRODUCT LINE:

 PRIMARY DEVICES - PARSHALL FLUME LINERS,  VENTURI TUBES  AND NOZZLES,
 DALL FLOW TUBES,  KENNISON OPEN FLOW NOZZLES

 SECONDARY DEVICES - "CHRONOFLO" TRANSMITTER  AND  RECEIVER UNITS, PRESSURE
 SENSORS,  TOTALIZERS,  AND INDICATORS

 DESCRIPTION:

 BIF,  a unit of  General Signal Corporation, has been active in the water
 flow measuring  field  for over 100 years.  Their  primary flow measuring
 products  include  such devices as Parshall flume  liners,  the recently
 developed Universal venturi tube which has largely replaced their Dall
 flow tubes, and Kennison open flow  nozzles.   BIF also offers the Solids
 Bearing Fluids  (SBF)  Flowmetering System, which  is reported to provide
 precise,  highly sensitive detection of differential pressures created
 by Universal  Venturi  Tubes  when the measured fluid is high in suspended
 solids.

 BIF's secondary units  are represented  by  several  Chronoflo transmitter
 and receiver  units  for indicating flow depths in  primary  devices.

 Parshall  Flume  Liners  -  BIF's precision-molded, one-piece plastic
 Parshall  flume  liner,  Model 141,  is  said  to  accurately duplicate Parshall
 flume proportions.  It is light-weight  and can be easily installed with-
 out the aid of  a  crane or special tools;  there are also no seams re-
 quiring special cements  or  sealing  compounds.  BIF plastic Parshall
 flume liner Model 141  is available  in  throat width sizes ranging from
 7.62  cm (3 in.) to  2.44m (8  ft)  to accommodate flow rates ranging from
 75.7  kid  (.02 mgd)  to  341,255 kid (90.16 mgd).  Parshall flumes were
 throughly treated in Section VI and will not be discussed further here.

 Universal Venturi Tube - BIF has developed a proprietary, differential-
 pressure primary device that combines the metering performance of the
 classical venturi tube with some of the more desirable features of dif-
 ferential pressure devices such as the Dall flow tube.  It offers ex-
 tremely short laying lengths  (less than half that of a short  form
 classical venturi tube), a great magnification of the differential
pressure signal (about twice that of classical Venturis), and low per-
manent head loss  (almost as little as a Dall tube).   The advantages
offered by the Universal Venturi Tube are due to  its unique hydraulic
design, especially from the inlet to the throat tap  (see Figure A),
                                  177

-------
that "conditions" the flow by creating a consistent artificial tur-
bulence in the throat flow pattern so that readings are stable and
predictable.  No blending radii are used, so flow separation and
stream-line bending are employed as in the Ball tube.
        -t M—W  .'
             ..t^CORNBt INLET UP
       JU4
                             Figure A


 The Universal Venturi Tube is  available in  line  sizes from 2.5cm  (1 in.)
 to 1.2m (4 ft)  as stock and up to 2.4m (8 ft)  on special order.   Even
 larger units can be made on request.  Series  180 Universal Venturi Tubes
 are available as insert types  or flanged types.   Standard tubes have
 cast iron bodies and bronze throats  with the  cast iron  surfaces (both
 interior and exterior) finished with tar or Bitumastic  paint.  A  large
 variety of other materials are available in weldment form, and fiber-
 glass reinforced plastic insert types are also standard construction.

 The tube coefficient is virtually  independent of the Beta ratio (ratio
 between throat and inlet diameters), the pipe Reynolds  number  (above
 about 50,000), and line sizes.  There is virtually no installation
 effect caused by upstream piping configurations, and downstream piping
 causes no effect whatsoever.  As a result,  uncalibrated accuracies of
 ±0.75% can be guaranteed and,  with calibration,  ±0.25%  is achievable.
 Standard ranges are around 5:1.

 Kennison Open Flow Nozzle - This open flow nozzle is a  simple  device for
 measuring flows through partially filled pipes.   The nozzle  handles low
 flow and wide flow ranges with ease.  Because of its high accuracy,
 non-clogging design and excellent head versus flow characteristics, the
 Kennison nozzle is well suited for the measurement of  raw sewage, raw
                                   178

-------
and digested sludge, final effluent, and trade wastes.  The Kennison
Nozzle is constructed of high tensile cast iron.  The piezometer vent
opening is bushed in brass and is equipped with a bronze-mounted manual
vent cleaner.  Hydraulically-operated vent cleaning can also be used
where the nozzle is installed in inaccessible places.  The nozzle is
available in inlet diameters of 15.2 to 91.4 cm (6 to 36 in.) and will
accommodate flows of 340 to 53,000 £pm (90 to 14,000 gpm).

Uncalibrated accuracies of ±2% for a range of 10:1, ±3% for a range of
15:1, and ±5% for a range of 20:1 have been demonstrated.  Special
laboratory calibration will assure accuracy within ±1% of actual flow
for a range of 20:1.  A Kenniflo rate.indicator is available for use
with the nozzle to provide visual evidence of instantaneous rate of
flow.  This indicator can be graduated in gpd, gpm, or mgd as well as
inches of head.

Solids Bearing Fluid Flowmetering System (SBF) - As shown in Figure B,
the SBF system is built around a combination of components — the
primary element, a Universal Venturi Tube Model 185 (UVT) (center); two
pressure sensing probes (upper right);  and a differential pressure
transmitter (lower left).  All of these components may be purchased .
individually.  Claims made for this system include:

     •  No electrical components are in contact with line fluid.'

     •  Water purging is eliminated.

     •  No circuit fouling or drift occurs.

        Instrumentation lines cannot be fouled by solids or
        entrained gases.

     •  System is unaffected by changes in static line pressure.

     •  Sensors can be removed while line is in service.

     •  System provides highly sensitive detection of flow signals
        produced by the venturi tube.

     •  All readings can be verified by a simple manometer.

The above is accomplished by the direct one-to-one transfer  of pressure
through a limp diaphragm which is held  at a  precise null position,
regardless of the magnitude of the measured  pressure,  by a pure silicon
fluid pressurized by a miniature hydraulic gear pump.   The liquid  is
delivered continuously through a filter to the probes  at a pressure
consistent with line pressure,  and exhaust fluid is fed back to the
                                  179

-------
Manometer connection
New SBF Flowmetering System has no electrical probes...
eliminates open type pressure taps subject to clogging. SBF
uses 'live" liquid filled null sensors that fit flush to the
flowmeter wall to transmit differential pressure signals
to instruments.
                             Figure B
                                     180

-------
 pump  reservoir.  Due to  the reset action provided by the supply-exhaust
 regulator unit associated with each probe, sensing diaphragm movement
 is  limited  to less  than  0.03 mm  (0.001 in.).  The center button of the
 diaphragm carries one end of an  armature, the other end of which is
 supported and centered by a spiral-spring bearing.  The end of the
 armature acts as a  baffle and floats close to the nozzle, regulating
 exhaust of  the fluid from the probe to the exhaust pressure regulator.
 This  probe  system is highly responsive to rapid pressure changes,
 essentially behaving like a filled-and-sealed system.

 Transmitter Units - BIF  manufactures several secondary transmitter
 units.  The Model 231-08 is a float actuated, free-standing, weather-
 proof Chronoflo transmitter-indicator mounted in a waterproof stand
 for level indication at  its location.  It also transmits readings to
 Chronoflo receivers for  remote indicating and recording.  The remote
 signal line requirements can be met by leased .signal facilities equi-
 valent to low frequency  telegraph channel capable of repeating time-
 duration impulse closures or a private metallic pair with a maximum
 loop  resistance not to exceed 2500 ohms.

 The BIF Chronoflo Model  231-09, used for flow rate determination, is
 identical to the Model 231-08 in appearance, weight, and signal line
 and power requirements.  Both are designed for stilling well operation.

 The BIF Chronoflo Model  231-34 is an in-stream, float-operated elec-
 trical transmitter  designed especially for use with head-area primary
 flow measuring elements  such as Parshall flumes, Kennison nozzles,
weirs, and  other open flow primary devices.   This transmitter operates
with  equal  facility over telephone or teletype lines,  telegraph cir-
 cuits, private signal lines, tone or microwave links.   The unit con-
 sists of the transmitter, indicator (optional extra),  a spherical,
 truncated float manufactured of ABS plastic, and a nylon-coated,
 stainless steel float cable.

 The Model 251-08 electronic differential pressure transmitter is  a
 compact transducer designed to translate a differential pressure  into
 a DC current signal and is designed to work with the SBF flow metering
 tubes only.

Miscellaneous - BIF also manufactures a line of pressure sensors  and
 Chronoflo receivers, recorders,  and summator/subtractor totalizer units
 for use with the primary and secondary units described above.

The SBF system's recording device is BIF's electronic  receiver and  is
available in either strip or round chart,  compact or full case models.
The electronic receiver will accept both 4-20 mA and 1-5 volt  signals.
                                  181

-------
SPECIFICATIONS:

Typical specifications for the BIF line of secondary flowmetering
devices are as follows:
Accuracy:

Dimensions:
Model 231-08 Transmitter

            ±0.5% for a range of 100:1

            143.5 cm (56-1/2 in.) height with a
            base dimension of 48-1/4 by 31 cm
            (19 x 12-1/4 in.).
Weight:                         136 kg  (300 Ib).

Power:                          115 VAC, 60 Hz @ 6 watts

                    Model 231-09 Transmitter

Standard Accuracy:              ±0.5% of maximum rate.

Extended Accuracy:              ±1% of  actual reading.

Range:
            10:1 for a maximum float travel of
            12.7 cm (5 in.)  to 30.48 cm (12 in.).
                                 20:1 for maximum float  travel  of
                                 30.48 cm (12 in.)  to  76.2  cm (30  in.).

                     Model 231-34 Transmitter

 Standard/Extended Accuracy:      ±2%/0.5% of maximum instrument reading.

 Range:
             10:1 for maximum float travels  from
             12.7 to 30.5 cm (5 to 12  in.);
 Dimensions:
             20:1 for maximum float travels over
             30.5 cm (12 in.), except on applica-
             tions with Parshall flumes or Kennison
             nozzles where head at maximum rate is
             less than 2.54 cm (1 in.) for maximum
             float travels up to 45.7 cm (18 in.),
             or 3.81 cm (1.5 in.) for maximum float
             travels over 45.7 cm (18 in.).

             Float - 15.24 cm (6 in.) dia.

             Float Cable - 0.09 cm (0.035 in.) dia.
                                  182

-------
p°wer:                          115 VAC, 60 Hz, Single Phase

PRICES:                                                      ......

Standard prices not available at the time of this writing.

COMMENTS:

Parshall flumes and Kennison open flow nozzles were discussed fully in
Section VI and will not be commented upon further here.  The Universal
Venturi Tube would appear to be one of the better differential-pressure
type primary devices for use with sewage.  Its requirements for full
pipe flow and. small range (5:1) may limit its. application, however.
The pressure probes used in the SBS would seem useful for other
differential-pressure devices and can be purchased separately.   They
could be used with existing'differential pressure devices where line
plugging or other problems have been high and maintenance troublesome.
                                 183

-------
MANUFACTURER:  BRAINCON CORPORATION
               A COMPANY OF TALLEY INDUSTRIES, INC.
               MARION, MASSACHUSETTS  02738
               TELEPHONE (617) 748-1085

PRODUCT LINE:  CURRENT METERS

DESCRIPTION:

The Braincon Corporation produces two basic types of primary current
meters.  The type 381 and 1381 Histogram current meters utilize 2/3 and
full size Savonius rotors, respectively, and record current rates on
16 mm film by taking time exposures of radio-luminous sensor indicators.
Braincon maintains complete processing and data translation facilities.
These current meters will not be discussed further since application in
the measurement of wastewater flow rates is inappropriate.

Braincon has developed a Model 720 electromagnetic current meter that
is capable of monitoring flows between 0 to 2 m/s  (6.6 fps).  It uses
an orthogonal array of four electrodes in the sensor head to present
instantaneous readings of the N-S, E-W components of the flow.  The
output voltage varies linearly with the velocity of the fluid flow over
the sensor head.  The Model 720 meter utilizes an oblate ellipsoidal
form (discus) probe that efficiently preserves laminar flow over a
generous range of adverse conditions.  Of interest is its superior per-
formance improvement over historically accepted mechanical transducers
such as the Savonius rotor.  Also noteworthy are the total freedom from
any mechanical designs; the use of a solid state fluxgate magnetometer
rather than a conventional compass; its high resistance to fouling;
lower meaningful measuring thresholds; the use of  Cartesian coordinates
rather than polar; instantaneous readout of N-S, E-W vector components;
high sensitivity to the physical environment; a faithful cosine response;
and less application dependency in critical wave-zone effect areas.

The 720 current meter can be used with a variety of readout devices if
the proper interface is provided.  Lengths of electrical cable up to
approximately 30m  (100 ft) are provided as standard equipment with the
Model 720, with additional lengths available.
 SPECIFICATIONS:

 Output:


 Accuracy:

 Threshold:
±2 VDC full scale (other ranges
available)
±1.5 cm (0.6 in.)/sec or 2% of full
scale
< 2 cm (0.78 in.)/sec
                                   184

-------
Resolution:
Power:
Operating Temperature:
Length:
Diameter:
Weight":
                                 0.5  cm (0.2  in.)/sec
                                 24 ± 4 VDC
                                 -2°C (28°F)  to  40°C (104°F)
                                 107.6 cm (42.35 in.)
                                 20.3 cm (8 in.), maximum
                                 23 kg (50 Ib)
PRICE:  Standard surface readout model:  $5,000
        Deep-water, long-term implant model:  $8,000
COMMENTS:                                     '

This electromagnetic current meter was  designed for oceanographic ap-
plications, but may find some use as a portable current meter for
attended operation in measuring wastewater flows.  Its low upper veloc-
ity limit will severely restrict its use, however.
                                185 .

-------
MANUFACTURER:
PRODUCT LINE:
DESCRIPTION:
BROOKS INSTRUMENT DIVISION
EMERSON ELECTRIC COMPANY
407 WEST VINE STREET
HATFIELD, PENNSYLVANIA  19440
TELEPHONE (215) 247-2366

VARIABLE-AREA FLOWMETERS, TURBINE FLOWMETERS, POSITIVE
DISPLACEMENT FLOWMETERS PROPELLER METERS, LIQUID LEVEL
INSTRUMENTS, ELECTROMAGNETIC FLOWMETERS, ETC.
Brooks manufactures a complete line of glass and metal metering tube
variable-area flowmeters (rotameters) in sizes to 12,000 &/m (3,200 gpm)
and priced from $50 to $6,000.  A number of pneumatic or electric trans-
mitters, receivers, alarms, etc., are available as accessories.  Noae of
these is considered suitable for wastewater flow measurement and,
consequently, no further discussion of them will be given.

Primary Devices

Brooks turbine flowmeters are manufactured in six different series for
use in various types of service, including chemical, cryogenic, air-
craft fueling, and petroleum pipelines, etc.  Ranges of 10:1 are stand-
ard, and accuracies as great as ±0.15% (with repeatability within
0.015%) are available with the Series M viscosity-compensated turbine
meters.  Prices range from $340 to $13,800.  Brooks also offers a com-
plete line of accessories including indicators, totalizers, printers,
etc.

Brooks manufactures nutating disc, oval gear, oscillating piston, and
bi-rotor type positive displacement meters in various models and sizes,
all of which are designed for clean fluid service only.  The same is
true of their bulk water propeller meters.  Since their application to
wastewater flows is not recommended, they will not be described
further.

The Series 7100-7200 electromagnetic flow transmitters manufactured by
Brooks are solid state flow rate sensing elements.  A typical unit is
depicted in Figure A.  They are designed to withstand tough service
applications such as corrosive, humid and dirty environmental condi-
tions, wide variations in temperatures, and high vibration loads.  All
adjustments are precise and are made externally; once set, there is no
change.  The three-electrode design is immune to changes in conduc-
tivity of the metered liquid.  The transmitter utilizes an integral
FET type preamplifier  (impedance converter) to provide a low impedance
output signal to permit long lengths of interconnecting cables without
                                   186

-------
        >,                     Figure A


regard to liquid conductivity or adverse effects of noise pickup.
Brooks-Mag transmitters, in conjunction with Brooks-Mag signal convert-
ers, provide output signals which are compatible with almost any manu-
facturer's secondary equipment.  Electromagnetic transmitters and
signal converters are fully interchangeable and are adjusted and cali-
brated independently of each other.  The transmitter uses a potentiom-
eter to adjust a reference voltage whose ratio to the signal voltage
is constant in all transmitters regardless of size, materials of con-
struction, and liquid being metered.  Signal converters are always
adjusted to identical input values.

Standard meter sizes are from 0.25 cm (0.1 in.) to 1.2m (4 ft), and
units up to 2.4m (8 ft) are available on special order.  Normal veloc-
ity ranges are 0 to 9 m/s (30 fps), and standard accuracy is ±0.5% of
full scale over the entire flow range.  The design features a short
laying length; e.g., a 61-cm (24-in.) diameter meter is only 76 cm •
(30 in.) long.  Type 304 stainless steel is the standard metering tube
                                 187

-------
material, and various line materials such, as neoprene, gum rubber,
polyurethane, etc., are available.  Among the units other design
features are:

     •  LOW POWER CONSUMPTION - yet has high signal-to-noise
        ratio; can operate.empty with power on.

     •  LOW INSTALLATION COST - only a single conduit between
        transmitter and signal converter.

     •  SEALED METER HOUSING - weather resistant-protects coils
        which are mounted  (for easy serviceability) on outside
        of flow tube.  Meets NEMA 4 specifications.  Submersible
        design optional.

     •  POSITIVE ZERO RETURN - optional zero level locking circuit
        actuated by remote contact.  Holds output signal at zero
        flow rate value.

     •  UNAFFECTED BY CHANGES - in conductivity, temperature,
        pressure, density, and viscosity.

     •  ADJUSTABLE FLOW RANGES - full scale deflection can be
        easily set for any flow rate within the limits of the
        transmitter.

     •  IMMUNITY TO STRAY  VOLTAGES DUE TO UNIQUE ELECTRODE
        BALANCE SYSTEM - eliminates the need for adjustments.

     •  LONG  CABLE LENGTH  - distance between transmitter and
        signal converter is not limited by  the conductivity of
        the liquid.

     •  ELECTRODE CLEANERS -  optional ultrasonic, or mechanical
        scraper in only complete  line of cleaners available.
        Cleaners prevent accumulation of matter on transmitter
        electrodes which could affect metering accuracy.

      •  PROTECTIVE SHIELD/GROUNDING RING -  (optional) prevents
         damage  to meter lining materials when  handling abrasive
        and  solids-bearing liquids.

 Where  it  is not desired to time-share one  signal converter with  several
 electromagnetic flow  transmitters, Models  7700-7800 are  available.
 These  models  are  essentially  a Model 7100-7200 flow transmitter  with
 an integrally-mounted signal  converter.  Figure B  depicts  typical
 configurations.
                                  188

-------
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                                             189

-------
Secondary Devices

Signal Converters - Series 7300 Signal Converters are all solid state
instruments which, receive the electrical output signals that are
linear with flow rate.  There are no servo motors, balancing slidewire,
or other components that can wear out.  The Brooks Model 7300 Series
Signal Converter amplifies and converts the AC output signal from the
flowhead into a DC signal.  Since the DC signal is directly propor-
tional to the liquid flow rate, it is used to drive a meter on the
signal converter that indicates percent of maximum flow.  The DC signal
can be adjusted for various operating ranges, and can be used with in-
dicators, controllers, recorders, and systems that require direct
current inputs for operation.

The AC flow rate signal from the flowhead is coupled into an impedance
converter having an input impedance of- approximately 2000 Mohms.  The
signal is amplified, converted to DC, and coupled to a divider.  Simi-
larly, the reference voltage from the flowhead is converted to DC, ,
amplified, and coupled, in the proper sense, to the divider.  A con-
stant DC multiplier signal (factory pre-set) is coupled to the divider
for scaling purposes.  The specific function of the dividing feature
is to produce a ratio between the signal and reference voltages for
all specified flow rates.  Fluctuations of primary power causes pro-
portional fluctuations of both signal and reference voltages. !There-
fore, by maintaining the ratio constant for a given flow rate, the
primary power fluctuations are ignored.  The computed output signal is
then conditioned as required and transmitted to the users receiving
devices.

Series 7400 Signal Converters are all solid state devices which receive
the electrical outputs from Brooks electromagnetic flowmeters and con-
vert these outputs to useable electrical output signals that are linear
with flow rate.  The signal converters are integrated units of modular
design capable of high system accuracy with a minimum of components.
The Brooks Model 7400 Series Signal Converter amplifies and converts
the AC output signal from the flowhead into a DC signal, or a pneumatic
signal.  Since the signal is directly proportional to the liquid flow
rate, the meter on the signal converter directly indicates percent of
maximum flow.  The output signal can be adjusted for various operating
ranges and can be used with indicators, controllers, recorders, and
systems that require DC or pneumatic inputs for operation.

The electrical output from the electrodes in the flowmeter is amplified
by a high impedance preamplifier.  This signal is combined with a
reference signal and then fed to a servo,-amplifier which, in turn,
powers a servo-motor.  The servo-motor drives a totally enclosed slide-
wire to achieve a "true null-balance by balancing a reference voltage
                                  190

-------
(fed through the slidewire) against the signal voltage.  In  addition,
the servo-motor operates the pointer which indicates flow rate, and
also rotates the cam which actuates the pneumatic transmitter  or
integrator.

Design features common to both the Series 7300 and  7400 signal con-
verters include:

     •  HIGH ACCURACY - Standard accuracy is ±0.5%  full scale
        output.

     •  COMPLETE INTERCHANGEABILITY - All units interchangeable
        with each other and with other signal converters from
        Brooks.

            SUMMARY OF 7400-SERIES SIGNAL CONVERTERS
Model
Number
7410
7411*
7430
7431
7450
7460
7470
7475
7490
7495

Flowrate
Indicator Dial
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
READOUT
7-Digit '
Counter
-
-
Yes
-
-
-
Yes
Yes
'
Yes
Pneumatic
Signal Output •
-
-
-
-
Yes
- ,
Yes
-
-
-
Current
Voltage
Output
- -
-
-
-
-
Yes
-
Yes
-
-
Output
Resistance
: -
-
-
. - .
-
-
- •
-
Yes .
Yes
Telemetry
-
-
- •' '
Yes
-
-
-
-•'
::
-
   8-1/2 inch 'indicator dial
        LINE VOLTAGE COMPENSATION - Inherent compensation for line
        voltage variations.

        EMPTY PIPE ZERO - Output goes below zero when flowmeter
        electrodes are not exposed to conductive liquid  (standard).
                                 191

-------
     •  MULTIPLEXING - One signal converter can be time shared with
        several flowmeters.

     •  LEAD LENGTH - Signal is not affected by lead length.

     •  MINIMUM INSTALLATION COST - Only one conduit is required
        between flowmeter and signal converter.

     •  MULTIPLE RANGE - Front-of-panel range selection available,
        or ten-turn potentiometer mounted on printed circuit
        board (optional).

     •  SERVICEABILITY - Chassis may be pulled out for inspection
        without shutting down flow or interrupting output.

     •  MOUNTING - Cases available for flush panel, wall or pipe-
        stand mounting.  Cases available in standard, weather-
        proof, or explosion proof construction.

Continuous Level Measurement and Control Systems - The Brooks "Maglink"
liquid level system was specially designed for use in pressurized tanks
or in open vessels in chemical service, where severe conditions of
corrosion, temperature, and pressure may occur.  All parts in contact
with the liquid are made from stainless steel, plastic, or special
materials, thus enabling the equipment to be used for most applica-
tions in the chemical, food, and allied industries such as liquified
gases, acids, etc:  The "Maglink" magnetic system has a sufficiently
strong coupling to withstand even the most severe fluctuations in
liquid level within the tank.  The unit is schematically illustrated
in Figure C.

Any change in liquid level moves the float, which contains an annular
magnet.  The float traverses a sealed guide tube.  The flux linkage
between the float magnet and the tape magnet- within the tube transmits
the movement via the tape, to the indicating mechanism in the head.
Backlash in the indicator mechanism is completely eliminated by means
of a constant torque spring, which also serves as a take-up device for
the tape and compensates for the weight of the magnet.  The density of
the liquid is accomodated by the range of floats available.  Design
features of the unit include:

     •  Sealed system - for pressure or vacuum service
     •  Materials of construction for corrosive service

     •  High accuracy
     •  No calibration required
                                 192

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                    Figure G

Remote transmission, pneumatic or electric
Good readability - 25.4 cm (10 in.) direct reading dial
Mechanical operation, inherently explosion proof
Unaffected by foam
Simple to operate and maintain
Operates on any liquid specific gravity
Interface measurement
Weatherproof case (standard for 25.4 cm dial only)
                        193

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        •   Typical float  designs  are as follows:
Dlomi
Inches
ter •
mm
Height
Inches 1 mm
Mln. Liquid
Density
in gm/cm^
Max
pre
PSIG
oper.
ssure
kg/cm2
Max.
tempe
°C
oper.
rature
°F
Float
Identification
Float Application
Floors in Stainless Steel
9-1/2
5-1/2
7-1/2
8-1/2
10-1/2
241
144
190
216
266
3
5



Floats in Polypropylene,
9-1/2
7-1/2
4-3/4
3-1/2
241
190
121
89
3
2-1/2
5-1/2
7
76
127



0.55
0.85
0.55
0.45
0.28
50
150
350
250
120
3.5
10.5
22.5
17.5
8.5
250
250
250
250
250
480
480
480
480
480
0
B
C
C
C
for standard use
for small branch entry
for medium pressures
same
same, and for low density liquids
Polyethylene, PVC
76
64
140
178
0.55
1.1
0.85
1.1
15
300
100
100
1.0
21.0
7
7
100
100
100
100
220
220
220
220
0
E
F
F
for standard u5_
solid-for high pressure applications
for small branch entry
same
Glow Float (Pyrex)
5-3/4
'146
7
178
0.68
Interface floats
6
7-1/2
152
190
2-3/4
2-1/2
70
64
See
note
45

200
300
3.2
250
480

14.0
21.0
100
100
220
220
G

E*
E**
For highly corrosive applications

for interface measurement with
adjustable weights
 Minimum difference in liquid density 0.2 gm/cm^
 • Stainless Steel            ** Polypropylene, PVC, Polyethylene
I	I Recommended float desii
                                                                                   gn
Standard floats are illustrated - special floats can be designed to suit more difficult applications.
                                                194

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     •  Materials of Construction include:
                                 316 SS, Polypropylene, PVC
                                 Teflon-covered SS
                                 316 SS, Polypropylene, PVC
                                 Glass, Mbnel
Guide Tubes and
Mounting Flange - Std.:
              Optional:
Floats -          Std.:
              Optional:
Cases -       Die-cast Alum, (with transmitter or switch)
              Rigid pplyurethane cover & fiberglass housing
              (std.)
Ranges:
Dials - Any range from 0 to 2 ft (min.) to 0 to 36 ft (max.)
Tapehead - Any range from 0 to 2 ft (min.) to 0 to 16 ft (max.)
Scales:
Standard                 Graduated in ft., in., or mm.
Special                  Graduated in units of weight or volume
                         of material
Performance:
Sensitivity -
All units below 5.5m  (18 ft) - float movement ±1.6 mm (1/16 in.)
All units 5.5 to 10.9m (18 to 36 ft) - float movement ±3.2 mm
(1/8 in.)
        Accuracy -
                         ±0.5% of max. indicated depth
PRICES:         "-.'..;
     "Brooks-Mag" Flowheads '
     "Brooks-Mag" Signal Converters
     "Maglink" Liquid Level Systems
COMMENTS:
                                           $800-$17,000
                                           $600-$12,000
                                           $200-$1,200
Electromagnetic flowmeters were discussed generically in Section VI and
no further comment will be made here.  The "Maglink" liquid level system
could find some application as a secondary device in conjunction with
flumes and weirs, especially in difficult sites.  All Brooks equipment
outputs are computer-compatible either as standard design or srvailable
option.
                                   195

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MANUFACTURER:  CONTROLOTRON CORPORATION
               176 CONTROL AVENUE
               FARMENGDALE, L.I., NEW YORK  11735
               TELEPHONE (516) 249-4400

PRODUCT LINE:  ULTRASONIC FLOWMETERS

DESCRIPTION:

Controlotron Corporation manufactures the Series 240 clamp-on ultra-
sonic flowmeter consisting of both a primary clamp-on unit and a
secondary flow display computer and readout unit for use with pipe
sizes from 2.54 to 152.4 cm (1 to 60 in.) in diameter.  The acoustic
technique employed is independent of liquid temperature, viscosity,
turbulence, etc.  The simple clamp-on installation requires no calibra-
tion or cutting of metal and can be performed by non-technical person-
nel.  The Series 240 transducer consists of a transmitter and receiver
unit positioned on opposite sides of the pipe.  The transmitter, con-
trolled by the flow display computer, injects an ultrasonic sound beam
into the liquid through the pipe wall.  The sound beam impinges on the
receiver after passing through the liquid and the pipe wall adjacent
to the receiver.  If the liquid is flowing in the direction of the
sound beam, the apparent speed of sound in the liquid is increased
(or decreased if flowing opposite to the sound beam).

The pipe construction and the type liquid within determine whether or
not the Series 240 ultrasonic flowmeter is suitable for a particular
application.  Controlotron will test 0.24& (8 oz) samples of the liquid
and samples of the pipe at no cost to the user to determine suitability.
Applications for which clamp-on models are not recommended by
Controlotron include pipes made of cast iron or any other material with
an irregular exterior or on pipes with linings that would attenuate
the acoustic signal.  Insert transducers are used for this type of
service.  These are similar to the transducers that are used for open
stream or channel measurement, and are made to order based upon the
application specifications.  Controlotron does not recommend use of
ultrasonic velocity measurement devices in liquids that are high in
undissolved solids or gases, e.g., slurries of sand-like particles,
foams, or other aerated liquids, etc.  Very rapid (less than 60 seconds)
changes in liquid characteristics (that would change its sonic velocity)
will result in temporary self-calibration failure and erroneous
readings.
SPECIFICATIONS:

Flow Range:
Resolution:
0-9.1 m/s (0-30 fps)
0.0015 m/s (0.005 fps)
                                  196

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Accuracy:
Repeatibility:

Indication:

Outputs:
Power:
Dimensions:

   Transducer -

   Flow Display

   Counter - 20.

PRICE:


COMMENTS:
                 From ±0,25% to ±2%, with ±1% of Full
                 Scale Reading nominal.   Larger sizes
                 are more accurate, and Controlotron
                 will quote expected accuracy for a
                 given application.

                 ±0.05%
                 Standard 3-1/2 Digits

                 Digital - BCD
                 Optional - Analog 0-10V, 4-20 mADC

                 Totalizer - 6 Digits                 ,

                 Alarm - Settable Hi and Lo Flow Alarms

                 115/230 VAC, 50-60 Hz, 75 watts'


L = Pipe O.D. + 15.24 cm (6 in.) (Approx)

- 25.4x33.0x38.1 cm (10x13x15 in.)
3x30.4x35.6 cm (8x12x14 in.)

                 Starts at approximately $2,000 for a
                 25.4 cm (1 in.) pipe.      • -
The equipment is factory calibrated either with water or the intended
liquid, as appropriate.  This is for fully developed flows with Reynolds
numbers exceeding 10,000.  It can be calibrated for any flow including
laminar, and Controlotron reports that models with settable flow range
factors and tracking of flow profile through the laminar flow region
will soon be available.  A zero offset adjustment may be required upon
installation.  Experience in metering raw sewage with this equipment is
limited at this time and no definite statements about its suitability
can be made.  The manufacturer is expanding its product line and adding
new features that may well increase the likelihood of their successful
use as flowmeters for storm and combined sewer discharges (but not in
the clamp-on configuration for most installations).  An acoustic level
gage that could be used with a number of primary devices such as weirs
and flumes is also under development.
                                  197

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MANUFACTURER:
PRODUCT LINE:
DESCRIPTION:
COX INSTRUMENT
DIVISION OF LYNCH CORPORATION
15300 FULLERTON
DETROIT, MICHIGAN  48227
TELEPHONE (313) 838-5780

VARIABLE AREA FLOWMETERS; TURBINE FLOWMETERS;
FLOW NOZZLES; FLOW INDICATORS
        Devices
Cox Instrument has long been recognized as a manufacturer of preci-
sion flow measuring equipment, especially as related to fuel, oil,
gas, and industrial process fluid flows.  The company proudly claims
that "over 95% of the world's commercially-built liquid flowmeter
calibrators now in use were designed and fabricated by Cox Instrument."
This includes one presently being used by the National Bureau of
Standards.  Cox has also produced custom designs and systems for
special applications.

The company offers a wide line of variable-area flowmeters.  Such de-
vices are not considered at all suitable for storm or combined sewer
applications and, hence, will not be discussed.  Cox also has a very
wide line of turbine meters; capacities range from 0.00044 to 1770 £/s
(0.000016 to 62 cfs), with accuracies to 0.05% of reading available
and response times better than 50 milliseconds.  One of these typical
turbine meters is shown in Figure A, which also indicates some of the
distinguishing features of a Cox turbine.  Turbine flowmeters are not
considered suitable for most sewer flows and will not be discussed,
further.

Cox also makes a flowmeter called the VR-30 which, it is claimed,
presents a new concept to the field of industrial flow measurement.
It uses the principle of variable reluctance:  a spring— loaded, force-
balance spool is displaced in a magnetic field by the force of fluid
flow.  This changes the coupling in an external circuit.  Because the
spool is displaced in a contoured cross— section, the square root is
extracted automatically, resulting in a linear output.  The advantages
to this approach are bi-directional output; unrestricted mounting posi-
tion; in-line installation; and low maintenance operation.  The VR-30
is said to handle corrosive, toxic, contaminated, or volatile fluids
or slurries, at pressures to 3,000 psi and temperatures to 121°C
(250°F).  It is accurate to ±2% of full scale.  Prices start at under
$300, complete with remote indicator.  The VR-30 may also be purchased
with a more sophisticated readout device for analog and pulse output,
providing for continuous process control or direct computer input.
                                  198

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Flow straightening design so
precise that additional
straightening is rarely necessary.
Pressure loss is insignificant.
Configuration of ro'tor blades is
designed to meet exactly the
requirements of meter and its
application ... providing high
response, accuracy, and linearity.
             Hermetically sealed pickoff
             provides a strong, high-frequency
             output signal.
                                                                           The lightweight rotor is the only
                                                                           Amoving part... no register .
                                                                           drives, no magnets. This design
                                                                           provides faster response, more
                                                                           accurate measurement,
                                                                           and longer life.
                                                      Precision ball bearings allow the
                                                      'rotor to move freely and respond
                                                      quickly to flow variations.
                                                      Bearings are field replaceable
                                                      ... no need to return entire
                                                      unit to factory. Different types
                                                      of ball bearings are used to
                                                      match the requirements of the
                                                      meter. Special sleeve bearings
                                                      of a variety of materials are
                                                      also available for heavy-duty
                                                      industrial applications.
                                       Figure A
                                              199

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This device may have some wastewater applications, but is not considered
well suited for most storm or combined sewer flow  measurements.  It
will not be discussed further.

Cox manufactures twenty standard sizes of flow nozzles (Figure B) in
two series with bore diameters ranging from 0.3 to 22.9 cm (0.128 to
9 in.).  The standard approach to bore diameter ratio is 3:1, but the
                                      —A-3
                             Figure B
larger sizes are available on request in a 2:1 ratio.  Cox nozzles are
available either calibrated or uncalibrated.  Nozzles are calibrated
by using a positive displacement prover tank, a standard "Master"
orifice, or both.  Pressure differential across the nozzle is deter-
mined by using a micromanometer accurate to 0.005 cm (0.002 in.) of
water.  Standard calibration is to within ±1<.0%.  With calibrated
nozzles, a curve of "Differential Pressure versus Flow Rate" (based
on 14.7 psia and 70°F) is supplied with a copy of actual calibration
data and correction factor determinations.  Calibration at other than
the standard condition noted can be obtained on special order.  Flow
nozzles were thoroughly discussed in Section VI and will not be com-
mented on again here.

Secondary Devices

In addition to turbine meter signal conditions and displays, Cox manu-
factures a number of basic electronic modules for signal conditioning,
conversion, display, etc., that could be used as "building blocks" in
assembling a custom system.  One such unit will be described as an
example, but such basic components lie outside the general scope of
this writing.
                                   200

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Cox Variable Time Base FIB - Using integrated circuit (1C) techniques,
the P1B module provides signal conditioning of low level AC signals
for input to counters.  The P1B may be used to increase the flexibility
of almost any counter currently made.  It is not limited to Cox-built
equipment, and will interface with most major manufacturers' counters.
In addition to signal amplification and conditioning,' the P1B module
provides gate, reset, and display control of ancillary counters.   The
variable time base (gate control) is a direct setting digital selector.
A four digit time base selector permits selection of 0.000-10.000 sec-
onds gating time in steps of 0.001 seconds.  The time base affords an
easy means of displaying the frequency output of a transducer in direct
reading units (e.g., GPM, RPM) .  The P1B may be used with Cox PSA coun
counter for the direct display of a frequency signal in engineering
units.  Turbine meters produce a frequency proportional to flow-rate.
By preselecting appropriate gate time, the display is in GPM units.

Design features include:

     •  Advanced 1C design employed.

     •  TTL (transistor-transistor logic) assures superior noise
        immunity.

     •  Designed for compatibility with pulse transducers present
        or future.

     •  Standard high sensitivity (3 mV) eliminates need for inter-
        mediate transducer amplification.

     •  Short circuit protection against both installation error
        and ancillary equipment failure.
                                 201

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MANUFACTURER:  GUSHING ENGINEERING INC.
               3364 COMMERCIAL AVENUE
               NORTHBROOK, ILLINOIS  60062
               TELEPHONE (312) 564-0500

PRODUCT LINE:  ELECTROMAGNETIC WATER CURRENT METER

DESCRIPTION:

The Series 600 VELMETER, an electromagnetic water current device, is
designed to measure flow velocity in oceans, streams, rivers, estuaries,
aqueducts, sewers, etc.  Operational features include no moving parts,
zero threshold, fast response times, cosine response, special noise
rejection circuitry, linear output, and anti-fouling coating.

The meter consists of a flow sensor connected to a signal converter by
means of a cable and is offered in several configurations.  These in-
clude an explosion-proof housing, NEMA 4 (weatherproof) housing, port-
able housing, rack-mounted panel, and kit form for the converter unit;
60-Hz or battery power; flange connection (with No-Foul protection)
type sensor; or streamlined type sensor (for use when flow direction
is known).

The VELMETER sensor produces a flow-generated voltage of approximately
20 MV per 0.3 m/s  (1 fps) of flow velocity.  The sensor's electro-
magnet requires a  (rms) constant current drive, which is provided by
the signal converter.  The converter accepts the flow-generated voltage
from the sensor, amplifies it, and conditions it to produce a final
analog voltage output of ±5 volts for ± full scale flow.  The converter
also conditions the signal to provide optimal filtering of spurious
wideband noise that is picked by the sensor (such as 60-Hz noises gen-
erated in waters near urban and industrial areas).

There are several  sensors that can be used with this metering device.
The Series 501 sensor incorporates one pair of detection electrodes
and provides an output voltage proportional to the vector component of
flow perpendicular to both the line connecting the two electrodes and
to the axis of the sensor.  The series 502 incorporates two pairs of
detection electrodes and provides two output voltages, measuring two
vector components  of water flow.  The series 81/82 sensors are,
respectively, single-component and two-component devices which produce
approximately six  times the flow signal power of the Series 500 sensor;
this sensor is said to perform within specifications for flow velocity
up to 15.2 m/s (50 fps).
                                  202

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SPECIFICATIONS:

Range:


Output Time Constant:


Maximum  Error Band:
Span or  linearity
Zero Offset
Random Noise, rms*
   Series 500 sensor
   Series 80 sensor
   Series 80 sensor
     with Magpower option
    Full Scale,  adjustable to 0.09,  0.30,
    0.9, 3.0, or 9.14 m/s (0.3, 1,  3,  10,
    or 30 fps)
    Adjustable to 0.1, 0.3, 1, 3, or
    10 seconds
  CONVERTER MODEL  NO.
611/612        631/632

±1             ±2
±0.01          ±0.05
0.006//T"
0.002//T"

0.001//T"
0.030//T"
0.010//T"

0.005//T"
                   UNITS


             Percent of Full  Scale
             Feet per sec.ond
Feet per second
where T is the output
time constant in
seconds
*  Apparent peak-to-peak noise  on a recorder depends  largely on chart speed;  but
   approximately,  apparent peak-to-peak noise is 6 times rms. value.
PRICE:   $2,000 - $3,000  depending upon configuration.

COMMENTS:

This device should find  some use as an attended survey unit  in its
portable configuration.  Because of the obstruction to the flow
offered  by the standard  probe configuration,  some ingenuity  would
haveito  be exercised in  mounting if damage from debris in  the flow
is to be avoided.
                                    203

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MANUFACTURER:  DANIEL INDUSTRIES, INC.
               P.O. BOX 19097
               HOUSTON, TEXAS  77024
               TELEPHONE (713) 467-6000

PRODUCT LINE:

PRIMARY DEVICES - ORIFICE PLATES AND METERS, TURBINE METERS, FLOW
NOZZLES

SECONDARY DEVICES - DIFFERENTIAL PRESSURE TRANSDUCERS, TRANSMITTERS,
AND CONVERTERS, INDICATORS, AND TOTALIZERS  (CALLED FLOW COMPUTERS)

DESCRIPTION:
 %
Primary Devices

Daniel Industries, Inc. manufactures a full line of orifice plates and
flanges, orifice metering tubes, bored orifice flow sections, and
orifice fittings for line sizes varying from 0.6 cm (1/4 in.) to 1.5m
(4 ft) in diameter.  Their "Senior" orifice fittings have a dual cham-
ber design  (Figure A) that permits the orifice plate to be removed
from pressure  lines safely and quickly; this facilitates regular in-
spection and maintenance.  "Junior" orifice fittings and "Simplex"
orifice plate  holders are made for application where line by-pass or
pressure shut-down is permitted.  A large range of orifice flanges for
use where it is not necessary to make regular plate inspections is also
offered, as are orifice meter tubes and bored orifice flow sections for
use where greater accuracy is required.

Daniel manufactures a "PT" line of liquid turbine meters (Figure B) in
sizes from  1.3 cm  (1/2 in.)  to 61 cm  (24 in.).  These meters are
intended for use where highly accurate measurement of large liquid
volumes is  required, e.g., custody transfer.  Each meter can be fitted
for bi-directional flow.  Normal  (linear) flow ranges are around 10:1
and extended flow ranges are from around 15:1 to 40:1, depending upon
size.

Daniel also manufactures a full  line  of precision flow nozzles  (ASME
long radius and ASME throat  top) including  flanged, weld-in, and
holding ring types in a wide variety  of materials  (Figure C).  For
highest metering accuracy, a fully assembled flow nozzle and meter  tube
is offered.  Large volume custom meter stations and proving systems are
supplied in virtually any size and capacity.
                                  204  '

-------
SIDE  SECTIONAL VIEW
CLAMPING BAR
SEAL.NGBAR
                                                        T°P
                                          UPPER CHAMBER
                                          BLEED VALVE
                                          UPPER PLATE  CARRIER SHAFT

                                          GREASE FITTING

                                          EQUALIZER VALVE (NOT SHOWN)

                                          SLIDE VALVE

                                          LOWER PLATE  CARRIER SHAFT
                                          SLIDE VALVE OPERATING SHAFT
                                          PLATE CARRIER (REMOVABLE)
                                          PLATE SEAL

                                          ORIFICE PLATE

                                          TAPS & LOWER CHAMBER
                    Figure A
                         205

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                           FT"  METERS
  RIM
ROTOR
BLADE
ROTOR
                           Figure B
                               206

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              FLANGED
           FLOW NOZZLE

  This type of nozzle has a flange on its upstream
end which is installed between pipe flanges to
hold the nozzle concentric with the inside of the
pipe. The nozzle flange can be furnished in any
series of facing (raised, ring-joint, etc.) specified.
                                                             WELD-IN

                                                         FLOW NOZZLE

                                                .This nozzle has a machined tongue around its
                                               greatest diameter which fits between beveled
                                               ends of both an inlet and outlet pipe section.
                                               The sections, with the nozzle in place, are firmly
                                               clamped and/or tack-welded together in perfect
                                               alignment before the finish weld is applied.
          HOLDING RING

          FLOW NOZZLE

  This nozzle is another welding type for instal-
lation  in pipe without flanges. The nozzle is
installed in a section  of carefully  selected and
internally  bored  pipe with  the curved nozzle
inlet facing upstream.               .  .
                                   Figure C
                                         207

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Secondary Devices

Daniel supplies a wide range of differential pressure transducers,
transmitters, counters, and indicators and totalizers (called flow com-
puters) for use with all of its primary elements.,  A typical differen-
tial pressure flow computer might take a 4-20 mADC signal that is
proportional to pressure difference and convert this into:  a visual
indication of flow rate on a front panel meter; a 4-20 mADC electrical
output that is proportional to flow rate; a visual, six-digit indica-
tion of totalized flow; and an electrical dry contact closure per each
totalizer advance.  Flow rate recordings are not normally supplied,
but could be on special order.  Similar outputs are available from
secondary elements for use with turbine meters.

COMMENTS:

Much of the Daniel product line was developed for the oil and gas
industry and is more typically suited for this application than for
measuring storm and combined sewer flows.  There might be some uses
for their flow nozzles and orifice meters in measuring sewage flow,
but the turbine meter is not at all suitable.  For this reason no
detailed specifications or prices will be given.
                                  208

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 MANUFACTURER:
DREXELBROOK ENGINEERING COMPANY
205 KEITH VALLEY ROAD
HORSHAM, PENNSYLVANIA  19044
TELEPHONE (215) 674-1234
 PRODUCT LINE:   LEVEL GAGES

 DESCRIPTION:

 Drexelbrook manufactures  a wide  line  of secondary flow measuring and
 indicating  systems  in their  Series  508  (see Figure A).  The Drexelbrook
 "Cote Shield"  flowmeters  provide reliable and accurate measurement of
 the flow of clean or dirty liquids  through virtually any head-area
 primary device such as flumes, weirs, etc.  The flowmeters contain no
 moving parts,  floats,  or  air purge  tubes; they cannot plug, and are
 unaffected  by  coating of  solids  such  as slush, mud, algae or slime,
 build-up, paper, sludge,  etc.  The  sensing element is static and can
 be  installed either directly in  the moving stream or in a stilling
 well.j.

 The sensing element is basically a  precision admittance-to-current
 transducer.  It will provide an  output current directly proportional
 to  the input admittance presented by  the sensing element.  Each meas-
 ured flow rate corresponds to a  specific level in the weir or other
 primary device.  This  variation  in  level will cause minute amounts of
 current to  flow from the  sensing probe to the grounded stream.  A com-
 pensated bridge circuit is used  to  accurately measure the change in
 current.  The  output of the bridge  circuit is a DC voltage which is a
 measure of  the true flow  rate.   The output voltage is amplified in a
 feedback amplifier  to  provide an output current directly proportional
 to  flow and unaffected by the output resistance.  The output current
 can be used to operate a variety of accessories such as remote meters,
 recorders, alarm circuits, and electro-pneumatic transducers.

 Drexelbrook has a number of the  Series 508 models available both with
 and without "cote-shield" action for clean or dirty liquids that vary
 in  calibrated  immersion depth of  the sensor probe from 30.5 to 91.5 cm
 (12  to  36 in.).  Standard systems are available for use with any 3/2-
 or  5/2-power low head-area device (most commonly used with weirs and
 flumes).  Linear systems  (e.g.,  for use with a sutro weir or Kennison
 nozzle)  are routinely made to order, and virtually any depth-discharge
 characterization can be provided on special request.   Both internally
 and  externally  (shaped) characterized probes are available.  For direct,
 in-stream applications where damage due to large debris (floating logs,
 rocks,  etc.) is a possibility, Drexelbrook offers an optional tilt-away
mounting in which the probe is held in the flow by an adjustable counter-
weight but is free  to pivot up out of the way when struck by an object
 in  the  flow.  This mounting is also recommended when extreme build-up
                                   209

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  EXTERNALLY
CHARACTERIZED
  (SHAPED)
SENSING PROBE
  INTERNALLY
CHARACTERIZED
SENSING PROBE
                                            -6 1/4	*1
                                           \i>       6| I—T
                                                                OPTIONAL REMOTE
                                                                            OUTPUT
                                                                            CURRENT
                                                                       117 VOLTS
                                                                       50/60 CYCLES
                              SERIES 508 FLOWFIETER
                                Figure A
                                      210

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 of  fibrous  materials  such as  rags  and paper are  expected.. As large
 build-ups occur,  the  increased drag on  the probe will cause it to tilt
 up  and allow  the  fibrous  materials to wash away.

 Optional integrators  (totalizers), batch counters, remote readouts,
 etc., are available as are such extras  as lighted meter case, explosion
 proof housings, special mountings  including extra-long probes, etc.
SPECIFICATIONS;

Accuracy:



Standard Output Current Ranges:



Load Resistance Effect:

Power!
Direct function of primary device.
Flowmeter output is linear within
±0.5%.

4-20 mA thru 0 to 1500 ohms
1-5 mA thru 0 to 6000 ohms
10-50 mA thru 0 to 600 ohms

0.1% from 0 to maximum resistance

95 to 145V, 50/60 Hz with a ±0.5%
effect on accuracy for input voltage
changes ranging from 95 to 135 VAC.
DC operation optional.
PRICES:
   Basic Series 508 Systems range from $553.00 to $1,371.00

COMMENTS:

These devices appear very well suited for use with various primary de-
vices to measure storm and combined sewer flows at many sites.  They
are essentially factory calibrated, and only a few field adjustments
are necessary.  It should be noted that the entire calibrated length
of the sensor is not available for accurate measurement of flow.  For
example, for 3/2 power law probes, the liquid level should always lie
between 1/3 and 3/3 of the calibrated length.  Thus, a 51-cm (20-in.)
maximum calibrated length sensor should not be used for heads greater
than 51 cm (20 in.) nor less than 15 cm (6 in.).  An additional in-
teresting feature is that, based upon an application description,
Drexelbrook will quote on a guaranteed performance basis.  If the
equipment does not perform within the quoted specifications, it may
be returned for free repair, replacement, or credit.
                                  211

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MANUFACTURER:
EASTECH. INCORPORATED
2381 SOUTH CLINTON AVE.
SOUTH PLAINFIELD, NEW JERSEY
TELEPHONE:  (201) 561-1000
                                             07080
PRODUCT LINE:  EDDY-SHEDDING PRIMARY DEVICES; TRANSMITTERS, FLOW
               CONVERTERS, INDICATORS, TOTALIZERS

DESCRIPTION:

Eastech Incorporated makes the VS-21 series vortex shedding element for
the measurement of flows of gases, liquids, and slurries.  Also offered
is a selection of secondary instrumentation including transmitters for
various applications, several flow converters, a digital rate indicator,
and a  totalizer.

Flowmeters

The VS-21 digital flowmeter  (patented  under the trade name of VS-21 Flow
Transmitter)  is the primary flow measuring device, and  forms an inte-
gral part of  various  flow  transmitters in the manufacturer's product
line - both "full pipe  flow"  type and  insertion flow variety.  In con-
junction  with the transmitter and sensor elements, this device utilizes
the principle (or effect)  of  vortex  eddy-shedding  to measure the flow
velocity.  The VS-21  generates  pulse signals  over  very  wide flow ranges
 (up  to 200:1) at a  frequency  proportional to  the flow rate.  It cur-
rently utilizes any one of four sensing techniques to measure flow.
Three  of  these techniques  employ thermistors; the  other makes use of a
 "shuttle-ball" concept, in which a  "captive"  hollow  nickel ball is
 driven by the effect  of vortex shedding.

 In the thermistor  techniques, an electrical  current  is  passed  through
 the thermistor, heating it and making it responsive  to  the cooling  ef-
 fects  of  flew.  The changes in flow velocity across  the thermistor  due
 to vortex shedding result in changes in its  temperature, thus  resulting
 in corresponding changes in its resistence.   In the  front face thermis-
 tor technique (Figure A),  two coated thermistors are bonded into  the
 front face of the flow element and operated differentially.
                              Figure A
                                    212

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The vortex shedding behind  the flow  element affects the direction of
flow impinging on the front face, causing out-of-phase velocity vari-
ations at the two thermistors.  This  is the approach used by Eastech
for wastewater and slurry flow measurement applications.

The "central" thermistor technique (Figure B) utilizes a passage drilled
through the flow element.   The generation of the vortices alternately on
either., side of the passage  causes flow to move back and forth in the
passage and across a single, removable thermistor sensor assembly which
is mounted through one end  of the flow element.
                    B.
                                    xxxxxxxxxxxxxxxxx
                             THERMISTOR
                              SENSOR
                                    ^xxxxxxxx xxxx/xx/
                            Figure B


The external thermistor technique is similar to that of the central
sensor except that it is located in a passage external to the meter.
Figure C shows this arrangement.
                            Figure C

The shuttle-ball method (Figure D) employs vortex shedding to drive a
hollow nickel ball back and forth along the axis of the flow element.
The motion of the ball is detected by a magnetic pickup.  The calibra-
tion factor of the meter depends only on the dimensions of the flow
element and the pipeline.
                                  213

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                                        ^xxxxxxxxxxxx
                             NICKEL
                             SHUTTIE
                             BAIL
                            Figure D
Flow Transmitters
As indicated by Eastech, the transmitter models discussed below are the
ones recommended for wastewater and slurry applications.

The Model 2210 and 2220 flow transmitters have flanged, spool style
bodies and removable VS-21 flow elements.  These devices feature two
front face thermistor sensors and an explosion-proof, close-coupled
solid-state amplifier.  This amplifier (also incorporated in the
Model 2500/2600 series) is provided to increase signal amplitude prior
to its transmission to a flow converter which way be remotely located
up to 762m (2500 ft) away.  As noted previously, the VS-21 generates
output pulse signals at frequencies linear with volumetric flow rate
over ranges up to 100:1 (200:1 optional).  Basic line sizes are from
3.8 to 15.2 cm (1.5 to 6 in.).  Other sizes are optional.

The Model 2510 flow transmitter also employs the front face thermistor
technique (Figure A) and has two wet-tap thermistors that can be re-
moved for inspection without interfering with the flow through the
device.  The thermistors are mounted on removable shafts flush with
the face of the flow element.  The transmitter may be connected with
flow converter instrumentation at distances up to 762m  (2500 ft).
This model, especially recommended for use on slurries and liquids
containing significant amounts of clogging solids, is offered in line
sizes ranging from 20.3 to 91.4 cm  (8 to 36 in.).

Models 2610, 2620, and 2630 are called "insertion flow" transmitters
but are actually velocity probes.  These devices have a shrouded flow
element with front face thermistor sensors  (see Figure A) mounted on
the end of a shaft passing through a sealed mounting flange.  The fixed
model 2610*  (Figure E) is used where the line pressure  can be relieved
 *  Also offered is the adjustable model 2640.   It is similar to the
    2610 except insertion depth can be adjusted with the flow trans-
    mitter installed.
                                  214

-------
    te
 stated
        rt                £he fl°" transmitter from the line.
        the manufacturer,  the Insertion depth cannot be altered
                                                            c
         the use of full pipeline meters, or where it is  ecessary
remove the  metering device for inspection or pipeline "paging"
transmitters may also be used to traverse across  a pipeSnf ?o det2
mxne velocity profile and are suitable for use in

uSdTi^h fl W±th the fUU P±Pe fl°W transmitter^,
used with flow  converters located up to 762m (2500

27-fcm
                                MODEL 2620
                               HOT TAP STYLE
                                                      away from the
                                             MODEL 2610
                                             FIXED STYLE
 DIAMETER OF
 HOLE OUT INTO
PIPELINE4 MAX,
  " MIN,
METER C/L.
                         Figure E
                              215

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Flow Converters/Indicators

Eastech offers several flow converters for use with the VS-21 flow-
meter.  These include Models 4100 and 4200 and the Model 44 digital
flow rate indicator.  The 4100 is designed for stationary or over-the-
road applications, accepts signals from a VS-21 flow transmitter, and
provides a conditioned pulse output.  Optional features include scaling
to engineering units, totalizers, and analog rate indicators.

Model 4200 is similar to the 4100 except that it provides field adjust-
able scaling to engineering units and can be panel mounted.

The Model 4400 displays flow rate in digital form.  It has a small plug-
in module which permits direct reading in any desired engineering units,

SPECIFICATIONS:

Model 2210 and 2510 Transmitters
Repeatability:

Linearity:

Calibration Accuracy:
Pressure Loss:
Response Time:
Minimum Measurable Flow:


Flow Capacity:


Turn-Down Ratio:


Model 2600 Series Transmitters

Repeatability

Linearity:
±0.1% of reading, or better
±0.5% of reading (at pipe Reynolds
numbers of 10,000 and above)

±0.25%
0.4 atm at m/s (20 fps)
1 msec @ 500-Hz signal frequency
Corresponding to pipe Reynolds number
of 5,000
2.54 cm (1 in.)* - 302.8 &/s (80 gpm)
91.44 cm  (36 in.)* - 340,650 A/s
(90,000 gpm)
10:1 & 100:1 (standard); up to
200:1  (optional)
 ±0.1% of reading or better
 ±2% of reading  (at Reynolds" numbers
 10,000 and above based on flow element
 dimension of  5.1 or 10.2 cm (2 or
 4  in.)
 *  Meter Size
                                   216

-------
  ±1%
  Negligible
  Same as Models  2200/2500  series
  Same as Models  2200/2500  series
  Same as Models  2200/2500  series
  5.1 and 10.2 cm (2 and -  4 in.)
  diameter
 Calibration Accuracy:
 Pressure Loss:
 Response Time:
 Minimum Measurable  Flow:
 Turn-Down Ratio:
 Element Size

 PRICES:
 Standard prices not available at the time of this writing.
 COMMENTS:
 There is  necessarily an obstruction to the flow with all of these de-
 vices,  so their use does not seem appropriate where large trash and
 debris  are present in the flow.  A well-conditioned flow is necessary
 for accurate readings, and a minimum of 20 to 40 pipe diameters in
 length  of straight pipe (15 to 20 diameters if straightening vanes
 are used) is required upstream of the meter and at least two pipe
 diameters of straight pipe downstream.  Gaskets upstream and near the
meter must not protrude into the flow.
217

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MANUFACTURER:
EDO CORPORATION
13-10 111TH STREET
COLLEGE POINT, NEW YORK  11356
TELEPHONE:  (212) 445-6000
PRODUCT LINE:  ACOUSTIC-DOPPLER FLOWMETERS; PROBES, RECORDERS

DESCRIPTION:

The EDO sonic flowmeter operates on the doppler shift principle and is
a further development of EDO's line of doppler current meters.  The
basic parts of the flowmeter  (acoustic prohe and receiver indicator)
are depicted in Figure A.


INDICATING
RECEIVER
^
                                DIRECTION
                                   OF
                                  FLOW
                             Figure A

 An acoustic probe, containing two transducers, is positioned in the
 flow.  It is normally oriented to point upstream, although the probe
 is actually bi-directional.  One transducer projects an acoustic
 signal, which is reflected by waterborne particles and disturbances.
 The reflected signal, frequency shifted proportionally to the velocity
 of the fluid, is received by the other transducer.  An electrical
 signal proportional to fluid velocity is converted to flow rate by
 means of processing circuits contained in the indicating receiver.
 The actual point of intersection of the two beams is one foot up-
 stream from the probe, so that measurements are made in an undisturbed
 region of the flow field.  Because the processing circuits are not
                                   218

-------
 sensitive to  amplitude variations, the flowmeter is immune to changes
 in impurity concentration  and peripheral noise.

 Significant claims have been made for this device with respect to its
 use in wastewater applications.  These are:

     ••   The probe does not clog due to sediment or silt as, for
      ..  example, the pressure ports of various flowtubes;

      •   The probe does not accumulate undue grease on the sensors,
         since they are located in a high-velocity region of the
         flow;

      •   The probe can  be easily wiped free of grease, rags, and
         other materials because, of its cylindrical shape.

 In addition to its applications to flow measurements in pipes, the EDO
 flowmeter can be used  for  open-channel velocity measurements.  The flow-
 meter has been used in fresh water, salt water, raw sewage and sludge.

 EDO provides  flowmeters and accessory equipment for both portable use
 and fixed installation.  The model 763F is designed for fixed applica-
 tions and model 763P is offered for portable uses.

 Model 763F -  The fixed flowmeter, with its automatic cleaning assembly,
 is  installed  at a specific point in the flow system.  The cost of an
 EDO fixed flowmeter installation is essentially constant, regardless
 of  the pipe-diameter, whereas the cost of magmeters, Venturis, and
 similar  in-line meters tends to increase dramatically with pipe diam-
 eter.  Due to its ease of  installation, the meter is particularly
 suited to retrofit applications.   If user requirements dictate,  it can
 be  used  in the interim period while an in-line meter is being repaired.
 Fixed flowmeter configurations can be altered to meet specific plant
 requirements.   For example, receivers for two or more probes can be
 packaged in a single receiver unit, and local indicators or totalizers
may be installed on the receiver panel.

An  automatic wiping mechanism cleans the probe periodically by with-
 drawing  and reinserting it through wiping glands.   The period .between
 cleaning  cycles is controllable and is set according to existing con-
ditions.  The cleaning can be remotely actuated from a control panel,
 if  chart-recorded flow readings indicate the necessity.

The mechanism provides unattended operation and requires only routine
preventive maintenance every 6 months.   No purging  is  required.
                                 219

-------
Model 763P - The portable flowmeter is general plant instrumentation,
inserted and removed as required, for plant flow surveys, trouble-
shooting, evaluation of equipment, etc.  Installation and insertion can
be made without interruption of flow.  Except for physical dimensions
and weight, differences in the respective receiver/indicator configura-
tions, and the fact that it is not equipped with automatic wiping
mechanism, the portable flowmeter operates essentially the same as the
fixed unit.
SPECIFICATIONS:
Ins trumentat ion
   Flow Range
   Pipe Size
   Accuracy
Acoustic  Probe
   Frequency
   Power  Output
   Transducer Spacing
   Transducer Angle
   Length of  Cable Probe
    Size of Probes
       Small
       Large

 PRICE:
                                0.03 - 4.57 m/s (0.1-15 fps)
                                15.24 - 243.84m (6-96 in.) dia
                                ±1.5%

                                3.0 MHz ±  .005%
                                1.3 watts
                                1.9 cm  (0.75 in.)
                                20°
                                up to 152m (500 ft)

                                1.9x91.4  cm (3/4x36  in.)
                                5.1x182.8 cm (2x72 in.)
                                3.048m  (120 in.)  (with probe  extended)
 Model 763F (Probe, Wiper Assembly, Receiver, Chart Recorder, Totalizer)
                                                 .	$ 9,345
                                                          $10,300
   With Small Probe 	
   With Large Probe	
Model 763P (Indicating Receiver, one Large or Small Probe,
Cables)	"     ™ *
COMMENTS:
                                                            2,930
 These devices are  essentially velocity probes and, hence, knowledge of
 flow velocity profiles is necessary in order to obtain flow discharge.
 They would appear  suitable for open channel as well as full pipe flow
                                    220

-------
given certain constraints.  The sensing probe necessarily presents an
obstacle to the flow and, in flows containing large trash or debris,
it might be physically damaged.  Hence, its -use would seem inappropri-
ate in this case.  Otherwise, the self-cleaning feature would appear
to be attractive and could allow its use in troublesome flows.  These
units are fairly new on the market, and wastewater application data
are scant.
                                221

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MANUFACTURER:   ENVIRONMENTAL MEASUREMENT SYSTEMS
               A DIVISION OF WESMAR
               905 DEXTER AVENUE NORTH
               SEATTLE, WASHINGTON  98109
               TELEPHONE (206) 285-1621

PRODUCT LINE:   ULTRASONIC FLOW MONITOR

DESCRIPTION:                                                    s

Environmental Measurement Systems, a division of WESMAR (Western
Marine Electronics,  Inc.), is now in production with their Ultrasonic
Flow Monitor,  UFM-200,  a completely packaged secondary device that
"ultrasonically" measures and records continuous liquid flow.  The
UFM-200 (Figure A)  is  calibrated, prior to shipment, to the customer s
                               ULTRASONIC FLOW MONITOR
                               UFM-200
                                MEASURES AND RECORDS CONTINUOUS LIQUID FLOW
                             Figure A

 flume or weir.  There is no contact with material being measured  (i.e.,
 transducer is mounted over the weir or flume), since the system operates
 on the "sonar-in-air" (echo-sounding) principle.  The sonar beam  gives
 a constant transmission of the distance from the top level of  the flow.
 This interval is  converted to a voltage which is converted to  flow
 rate and recorded, totalized, and displayed.  The UFM-200 is a complete
 system with electronics, total flow counter, water sample rate counter
 (adjustable), recorder  (strip chart), timer  (duty cycle), and  visual
 linear readout  meter.

 The system has  built-in circuitry that allows remote or portable  in-
 stallation through battery-powered operation.  The total flow  counter
                                  222

-------
 continuously displays the total amount of flow, in six digits, up to
 1 billion gallons (3,785 billion liters); the permanent recorder records
 the converted and calibrated flow output in gallons per minute on a
 6.35-cm (2.5-in.) inkless strip chart at a speed of 2.5 cm (1 in.) per
 hour.
 SPECIFICATIONS:
 Range:

 Resolution:
 Repeatability:
 Linearity:
 Output  Signals:

 Pulse Proportional  to  Flow:
 Sensor  Beam Pattern:
 Remote  Operation
 (Electronics to Sensor
 Separation):
 Input Power:

 Dimensions
   Enclosure:
   (JIG)
Weight:
   Electronics:
   Sensor:
PRICE:
Not available at time of writing.                ,
COMMENTS:                                     	"
Some users have encountered difficulty due to echos (false signal re-
turns) when using these devices in manholes.  Putting a plastic shield
around the transducer seems to solve the problem.
3m (10 ft)  (maximum)
41 cm (16 in.)  (minimum)
within 1%
within 1% .
within 1%
0  to 5 VDC  (proportional to head)
0  to 5 VDC  or 0 - 1 MADC (proportional
to  flow)
1 pulse every 1,000 gallons
7°  conical  included angle
Up to 91.4m (300 ft)
110/220 VAC, 50 to 60 Hz,
10 watts (or ±12 VDC)
36x31x15 cm (14x12x6 in.)


15 kg (3 Ib)
1 Kg (2 Ib)
                                 223

-------
MANUFACTURER:
PRODUCT LINE:
EPIC INC.
150 NASSAU STREET
SUITE 1430
NEW YORK, NEW YORK  10038
TELEPHONE:  (212) 349-2470

CURRENT METERS, COUNTERS/INDICATORS, STAGE
MEASUREMENT DEVICES
DESCRIPTION:

Eoic  Inc.  is  the U.S.-based outlet for precision instruments and ma-
chinery manufactured by  the West  German firm of A. Ott Kempten.  Epic
and Ott offer a line of  current  (velocity) meters and a varied selec-
tion  of secondary  flow measurement devices, including counters,
recorders, and indicators  and several stage measurement devices  (e.g.,
water level recorders, point  gage, and a  "flowmeter").  Most of  these
devices are designed primarily for measurement of water flows, but
several have  found application in the wastewater field.

fluent  (Velocity) Meters  -  Typical  current meters  in the Epic/Ott  line
Include  the Universal  types  10.002  (C31), 10.200, and 10.300   Types
 10 002 and 10.200 are  similar in that they both  produce signals  gen-
 erated by an  impulse device  actuated by  a permanent magnet so  that  the
 rotation of the propeller  is not slowed  down by  a  contact system; the
 signals  are totalized  by an electromagnetic counter connected  by cable
 to a magnetic switch,  mounted in the meter body.   It has  been  reported
 that the Type 10.002  (C31),  shown in Figure A, has  been used success-
 fully (in conjunction with a specially-designed  flow tube) by  at least
 one large municipal government in the measurement of effluent  flows.
 Types 10.002  (C31) and 10.200 are portable, battery-powered devices.

 Type 10.300  is a  permanent hydrometric flow measurement device.   Unlike
 the 10.002 and 10.200, this  instrument permits a direct determination
 of flow velocity  and  can be  permanently  installed.  As do the other two
 current meters, the 10.300 produces  a signal voltage that is propor-
 tional to water speed; this  voltage  can  be read from an indicator in
 m/s.  Telemetry of the measurements  is possible.

 The  type  propeller used,  and its diameter and pitch, is determined by
 maximum flow velocity of  the fluid into  which it is placed.  As shown
 in the following  table, there is a variety of propellers  for several
 applications ~ including oblique flows  as well as  straight flows.

 A variety of methods  for  indicating  and  recording  flow velocities is
 available:   direct  Indication via a  servo system  (for precision remote
 indication); four-digit digital readouts by  a converter  and readout
                                    224

-------
Figure A
Propeller
Ref. No. for
ordering
10.001.030.4.4
10.001.027.4.4
10.001.028.4.4
10.001.029.4.4
10.001.031.4.2
Component propeller
up to 45° oblique flow
10.001.032.4.4
Component propeller
up to 15° oblique flow
Type No.
engravec
4
1
2
3

A

R
Propeller diameter
mm in.
80 3 5/32
125 4 59/64
125 4 59/64
125 4 59/64

100 3 121/128

100 3 121/128
Propeller pitch
m. . in.
0.125 '.4 59/64
0.250 9 54/64
0.500 19 11/16
1.000 39 3/8

0.120 4 29/40

0.240 9 9/20
Max. flow velocity of water
m/sec ft./sec
1.25 4.1
2.50 8.2
5.00 16.4
10.00 32.8

2.50 8.2

5.00 16.4
Starting
speed
m/sec
0.04
0.03
0.04
0.05

0.04

0.05
    225

-------
device; continuous recording of flow velocity on a compensating recorder
Cespecially suitable for permanently installed velocity meters); and
recording of the measured value by a portable, battery-powered mini-
recorder (basically used with non-permanent meter installations).

Flowmeters - Epic offers the Type 22.001 "flowmeter" for  indicating,
recording, and counting the discharge at measuring weirs  or open chan-
nels and in unpressurized pipe lines.  A venturi flume can be provided
with this -unit.  A water level-recorder with an electrical output (0-
10 volts) is used as the measuring transmitter for the water level.
Various systems of level meters can be employed -- e.g.,  pressure level
gage,  tube level gage, pressure level gage with transmitter-amplifier,
float-type level gage, etc.  Figures B through F show some typical
applications of this meter.  The Model 22.001 combines a direct read-
ing indicator, counter, and strip recorder within a single cabinet.

1.  Metering with the pressure level gage

A pressure transmitter is fastened on the bottom of the measuring chan-
nel.   The device operates as an inductive measuring value sender.  The
mechanical part of the measuring value sender is a metal membrane.
The deformation of the metal membrane resulting from the pressure of
the water column standing over the sender is a function of the water
height H.  This deformation which lies for  the nominal range  in the
magnitude of  less than  0.2  mm  is measured with an inductive measuring
transformer and, over corresponding  electronics, converted into a
voltage  of 5  volts for  the  nominal range.
                              Figure B
 2.  Tube level gage (.1)
 In very muddy channels it is occasionally necessary, to clean the
 pressure level gage.  In this case, the tube level gage is especially
 suitable.  Here the inductive pressure transmitter is in the lower part
 of a tube.  The sender is designed in such a way as not to touch the
 liquid of the measuring channel.  For cleaning, the tube level gage is
 simply taken out of the liquid.  The measuring amplifier can be fixed
                                    226

-------
  directly at  the tuba tn order to have available at the measuring point
  a voltage for the level value of 0-10 volts.   This tube  level gage
  design offers the advantage that the installation can be made in the
  specific measuring channel  without  constructional modifications
                          Measuring
                          amplifier
                          10 V(H)
                        Transmitter.

                             Figure c

3.  Tube level gage  (II)

In this configuration, the pressure transmitter is mounted to a metal
foot which is anchored in the bottom of'the measuring channel.  In this
way the transmitter is always flowed around by the liquid, thus avoiding
the risk of getting polluted by deposition of mud, etc.  This level
TSi ^l^^einounted on a tube, which is arranged in the side wall
of the channel,  (By bedding the tube into the side wall, any dis-
turbing effect to the flow conditions in the channel will be excluded.)
                                  227

-------
                        ; Measuring
                        amplifier
                          o —10V
                                        T^
                                  Transmitter
                             Figure D


4.  Pressure level gage with transmitter amplifier

This gage is similar to the instrument described under item 1,  but in
this cafe, the amplifier is directly attached to the transmitter   At
the output, a voltage of 0 to 10V is released which corresponds to the
height of'the water level.  This transmitter can serve as level meter
for the flowmeter, but it is also especially suited as a transmitter
for the level indication in large tanks.
                                  228

-------
                                      Transmitter -t-
                                      amplifier
                                      0 —10V(H)
         i                    Figure E

5.  Float-type level  gage

In case where there is a float well existing at the measuring point,
the measurement of the water level H can also be effected by means of
a float-operated level gage.  A potentiometer converts the water level
into an electrical signal and applies it to  a measuring amplifier.
The output of this amplifier is a  voltage proportional to the water
height H which is led on to  a function print for the calculation of
the discharge quantity Q.  The function  print consists of electronic
units, so that a mechanical  cam is  not necessary for the determination
of the discharge volume.
                                                  Transmission line
                                                  0-*-10 V(H)
                                                  Measuring amplifier
                             Figure F
                                 229

-------
Counters - Epic markets a variety of counters ranging from simple,
electromechanical devices to fairly complex digital counters and in-
dicators.  Typical are the Type 12.000 (F4) Revolution Counter,  the
Type Z100 counter, and the 12.150 Revolution Indicator.  The three-
digit F4 counter (Ott 12.000) counts a maximum of 10 pulses per sec-
ond and is suited for operation with the Ott 10.002 (C31) current
meter, which generates a signal pulse at each revolution of its pro-
peller.  Two 1.5-volt "D" size batteries serve as the power source and
allow up to 48 hours of continuous operation without battery replace-
ment.  A stopwatch is used with this device.

The Z100 five-digit counter  is capable of measuring the length of pulse
cycles from voltage-free transmitters (e.g., current meters), up to a
maximum of 20 pulses per second.  It is powered by six 1.5-volt single
cell batteries, sufficient for about 30 hours of operation, at a rate
of eight hours of daily operation.

The 12.150  (F10) revolution  indicator provides direct  reading of pro-
peller revolutions per second.  It  features  three measuring ranges and
has a built-in accumulator with battery charger which  can be plugged
into a 110/220 VAC power source.  The counter is suitable only for
measurements where propeller revolutions are at least  1 per second.

Water Level Recorders '- Epic offers several  water  level  recorders  for
use with the Type 22.001 flowmeter  as well as with other types of^meas-
uring  devices.   Following  is a description of several  typical devices.
The Model 20.100(X)  is a horizontal water  level recorder for continuous
 recording of water  levels  in still  and  flowing waters.   Drum rotation
periods  are 24  hours,  8  days, and 32 days.

 The Model 21.001 transmitter and 21.356 receiver  are remote-controlled
water  level recorders.   The transmitter has  an  impulse sequencing  relay
 action for telemetering  water level data over short and long distances.
 The receiver is for use with two transmitters, with indication of  the
 water levels and their difference as well as recording of  two  water
 levels.

 Other models include a 20.250 (R16) vertical water level recorder
 especially suitable for ground water measurements, and a 20.300(XX)
 strip chart water level recorder for continuous recording.

 Gages - Gages include the Model 24.000 point gage which comes  with or
 without an optical indicator.  This device provides exact determination
 of water levels by means of a pinpoint with reading accuracies of
 1/10 mm, 1/1000 ft, or 1/100 inch.
                                    230

-------
 SPECIFICATIONS:
              Current Meter (Typical) - Model 10.300
 Starting Speed:

 Measurement Accuracy:
 Propeller Speed,  Maximum:
 Remote Transmission of
    Measured Values:
 Dimensions:
    Body
    Length (complete with
    propeller)
 Weight:
 0.035 and 0.045 m/sec
 (.114 and .148 fps)
 ±1.5% (from start of meter up to
   0.2 m/s)
   ±0.5% (0.2 m/s and more linearity
 error)
 720 rpm                          .   "..

 possible up  to 10km

 4  cm (1.57 in.)

 22.2 cm (8.74  in.)
 No data on 10.300.   Weights of other
 models  range from 2.7  to  9.1  kg  (6  to
 20 Ib).
                 Counter  (Typical) - Z100 Counter
Input:
Measuring Range:
Longitudinal line resistance of meas-
uring cable:  200 ohms (max.)
Cross resistance of measuring cable:
1.5 kphm (min.)
Load of signal transmitter:  10 mA
(max.)
Input pulse recurrence frequency:
20 pulses/sec (max.)
(a)  Preset time.   The. measuring time
     can be preset 0.1 sec ...999.9 sec
     adjustable in steps  of 0.1 sec
(b)  Preset count.   The number of
     pulses can be preset 1 ...  9.999
     Range  of time measuring
     0.1 sec ... 99.999.9 sec
                                  231

-------
Measuring Accuracy:
Dimensions:
Weight:
(a)   Preset time.   Measuring time
     inaccuracy:  +0.1 sec (max.).
     Error caused by measuring proce-
     dure:  max. -1 pulse
(b)   Preset count.  Error in length of
     time:  ±0.1 sec (max.).  Error
     caused by measuring procedure:  0

14x12.7x16 cm (5.5x5.0x6.3 in.)
(without operating elements and plugs)

  2.9 kg  (6.38  Ibs)
               T?1 n«mieter/Water Level Meters (Typical!
 Measuring Range of Water Level:
 Relative Error for Water Level:
 Possible Shapes of Measuring
    Channel:
 Error of the Water
    Level (H) - Discharge
    Quantity (Q) Function
    (in Transmitter):

 Total Error for Discharge
    Quantity Output:
 Output Voltage for  Water  Level:
 Output Voltage for  Q-Output:


 Output  Current for  Q-Output:

 Power:

 PRICES:

  Current Meters
0-30  cm (11.8  in.)
0-100 cm (39.4 in.)
0-150 cm (59.1 in.)
0-300 cm (118.1 in.)

0.5%
rectangular;  triangular;  round;
venturi-channel

 ±0.3%
 0-10V (nominal range)
 0-10V (nominal range)
 0-10V (nominal range)
 0-20 mA  (0-500 ohms)

 220 VAC,  40-60 Hz
     10.002-
     10.200-

     10.300-
                  $1,350-1,600

                    $825.00
                    $870.00
                                    232

-------
Counters
   Z100--


COMMENTS
                                                    — $200.00

                                                    — $925.00
         element current meters were thoroughly discussed in Section VI
         not be commented upon here.
                               233

-------
MANUFACTURER:
FISCHER & PORTER CO.
WARMINISTER, PENNSYLVANIA  18974
TELEPHONE  (215)  675-6000
PRODUCT LINE:

PRIMARY DEVICES - MAGNETIC FLOWMETERS, FLOW TUBES, FLOAT-ACTUATED
FLOWMETERS, PITOT TYPE MAGNETIC FLOWMETERS, PARSHALL FLUMES, AND
SLUDGE FLOWMETERING SYSTEMS

SECONDARY DEVICES - ELECTRONIC TRANSMITTERS  (BELLOWS AND MERCURY-
ACTUATED) , SIGNAL CONVERTERS, ELECTRONIC RECORDERS, AND INDICATORS.

DESCRIPTION:

The Fischer  and Porter  Company offers  a broad  and diversified  line of
products  for use  in various  flow  measurement applications  in the water
and wastewater field.   The company manufactures  a number of different
types of  flowmeters  and flow tubes, as well  as a plastic Parshall flume
and various  signal  converters.  The company  also markets a flowmeterxng
system specifically designed and  constructed to  continuously measure
 the flow of  sludge.   Figure A depicts  some typical installations ot
 primary flow measuring devices.

 Flowmeters - The type 10F1272 stilling well, float-actuated flowmeter
 measures flow rate in terms of the stage in flumes, weirs, and other
 head-area devices.   The flowmeter converts vertical changes ot ±loat
 position into corresponding units of liquid flow.  The float cable
 from which the float is suspended is wound on a drum inside the instru-
 ment   As the float rises and falls with changes in the liquid level,
 the float cable winds or unwinds from the drum,  causing the drum to
 rotate.  The position of the drum reflects the measurement of the liquid
 level.  The measurement is translated into the desired functxonal motion
 for recording, indicating, or integrating through mechanical linkages
 to a characterized cam attached  to  the drum.  When the flowmeter xs
 equipped with  an electric vacuum,  or pneumatic transmitter, the measured
 value can be  transmitted as a linear or non-linear signal  for remote xn-
 dicating, recording, or integrating.

 The Types 10F1275 and  10F1276 are in-stream,  float-actuated instruments
 that measure  the flow  rate  in terms of the  head  produced  by Parshall
 flumes,  rectangular weirs,  or other flumes  where head to  the  3/2 power
 is proportional  to  flow (Type 10F1275), or  by triangular  weirs
  (Type 10F1276).  The  flowmeters  transmit  an electric txme-pulse or  UL
 milliamp signal  proportional to  the flow  to receivers that indicate,
  record,  or  integrate the value.   These flowmeters are of  submersxble
  construction and can be equipped with specially-constructed transmitters
  for operation in hazardous locations.
                                    234

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TYPICAL INSTALLATION WITH TRIANGULAR WEIR
TYPICAL INSTALLATION WITH PARSHALL FLUME




                Figure A





                    235

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The Pitot-type (probe) magnetic flowmeter (10F1430 serxes) , shown in
Fiaure B, is designed especially for use in water and sewage.  It
SSSes the Fischer & Porter unique, characterized field princxple of
electromagnetic induction to produce an AC signal directly proportxoned
S^TSS rate.  Using this device, liquid flows can be measured xn
large rectangular, circular, or irregularly shaped pipes.  It  is to be
noted that 1? is strictly a velocity-sensing device, and measures only

SLe^S^^

                  i* S.^£-i^Ti23rS &1¥j
the end  of a support suspension.   The smallest recommended pipe line
size^or the insertion of the flowmeter  is  slightly less than one meter
 (36 in?).  In optional feature of this flowmeter  is its bi-directional
flow measurement  capability.

Another  flowmeter in the Fischer & Porter line is the Short Form
Saracterized Coil  (SFCC) Design Model  10D1430A  (Figure  C) .  This
 electromagnetic measuring device operates on the same prxncxple as the
Pitot-type Model 10F1430.  The SFCC meter differs from conventxonal
 electromagnetic flowmeters in that it uses a light weight  coil encased
within the liner of a metering tube instead of a heavy external field
 coil.   Meter sizes  range from 7.62 to 243 cm (3  to 96 in.) and ^xgh
 from 43 to 2,268 kg (95  to 5000 Ibs) .  Designed  for Ixquxds,  the meter
 is reported to  be unaffected by density or viscosity or  by normal up-
 stream or downstream piping configurations.  In addition,  electrode
 cleaning is available upon request for both standard and accidental
 submersed ("splashproof")  designs.  The meter can be mounted  in any
 aSude (although vertical is recommended) in the pipeline.   The manu-
 facturer slates categorically that full pipe flow conditions  must exxst
 in order for the meter  to obtain accurate measurements.

 Fischer and Porter also manufacture long form magnetic flowmeters
 (Type 10D1416A), which  have been in produttion for almost 20 years.
 The? are available in sizes  from 15 to  61  cm (6  to 24 in.) as standard
 and may \Hrdered in sizes  up  to 198 cm (78 in.), but the SFCC desxgn
 is recommended for the larger sizes.  This type  has been in servxce so
 long that it serves as a dimensional standard in many plant-layout
 specifications  and guides.
  Common features of all Fischer and Porter magnetic  flowmeters
  very high accuracy, very stable operation, extremely sensitive operation
  Tc2 measure liquid flow with conductivities as low as 0.1 mxcromho per
  centimeter),  and  direct digital computer compatibility.  Electrodes
  are field replaceable- with no loss in accuracy and  no need for
  r ecalib rat ion .
                                   236

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Figure B
      237

-------
                           METER TERMINAL BOX
CALIBRATION COMPONENTS
   (EPOXY POTTED)
                SIGNAL INTERCONNECTION
                   TERMINAL BLOCK
                                              CONDUIT SEAL
                                               ASSEMBLY (3)
 INSULATING PIPE LINER
                    METER ELECTRODE (2)
             -MAGNET COILS
      -EPOXY POTTING COMPOUND
-METAL METER BODY
                                  G! 1312
                                   c
                       Figure  C
                           238

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 Parshall Plastic Flume - The Type 10F1940 Parshall flume is a one-piece
 plastic -unit designed for the metering of liquids in open channels.
 Because of its unbroken flow lines which present no obstructions to
 cause build-ups of debris, the flume is particularly well suited to the
 measurement of liquids containing settleable solids.  The F&P flume is
 available in various standard throat widths ranging from 2.54* cm (1 in.)
 to 3m (10 ft).  The flume is constructed of corrosion-resistant, light-
 weight molded fiberglass reinforced polyester with integral stiffening
 ribs to make the unit self-supporting and eliminate external bracing.
 Options include integral stilling wells and staff gages.

, Flow Tubes - Fischer and Porter Series 10F1070 cast iron flanged flow
 tubes (Figure D) are differential-pressure producing, primary metering
 devices of a proprietary design which, it is claimed, produce a high
 differential with minimum head loss (2-4%).  Tubes are available for
 nominal line sizes from 10.2 to 61.0 cm (4 to 24 in.).  Four standard
 throat sizes can be provided in each line size.  The tubes are con-
 structed of high tensile cast iron with the throat sections available
 in bronze or s.tainless steel.

 The 10F1060 plastic insert type flow tubes (Figure E) contain outlet
 cones constructed of polyester plastic, reinforced with 30 percent
 fiberglass by weight and throats of either bronze or stainless steel.
 Tubes are available for nominal line sizes from 10.2 to 91.4 cm (4 to
 36 in.).  Four standard throat sizes can be provided in each line size.

 Sludge Flowmetering Systems - The patented Fischer & Porter Model
 10D1416/18C(s)  Magnetic Flowmeter is designed to continuously measure
 the flow of sludge.  This design uses the electromagnetic induction
 field of the flowmeter coils to produce an eddy current effect in the
 aluminum metering tube.   The eddy currents produce continuous heating
 within the tube while. _simultaneously transferring the heat through a
 "process-wetted" liner to prevent sludge and grease buildup.  To com-
 plement  this capability and provide greater accuracy of measurements,
 the manufacturer recommends the use of an optional feature - an ultra-
 sonic electrode cleaning device.   The output signal from the
 Model 10D1416/18C flowmeter,  representing sludge flowrate,  can be re-
 ceived by either a 51-1100DC series circular chart electronic recorder
 or indicator,  or a 50ED4000 or 50SF2000 series  signal converter.

 Flow Transmitters - The Fischer and Porter flow transmitters,
 Types 1451RB and 1453RB,  are bellows-actuated instruments designed  to
 produce  a 4 to  20 mADC linear signal proportional to changes in rate
 of flow  through differential  producers.   The differential pressure  is
 detected at the metallic bellows  pf the transmitter which uses  mineral
 oil as a fill fluid.   A torque tube assembly within the meter housing
 responds to differential pressure changes  and its movement  is  trans-
 mitted by an operating spindle to a linear variable differential
                                   239

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       Figure D
HIGH PRESSURE TAP
     PRESSURE TAP






        Figure E









             240

-------
 transformer (LVDT).   The output of the LVDT is received by solid state
 electronic circuitry for extraction of the square root function of the
 differential to produce an instrument output signal proportional to
 flow.                         ..

 The Type 1451RE and  1453 flow transmitters are mercury manometer-
 operated instruments which produce a signal similar to that of  the
 bellows-operated transmitter.   However,  the differential pressure is
 detected at the mercury-filled  wells of the transmitter.   A float in
 the low pressure well responds  to  the mercury level changes and its
 movement is transmitted by an operating spindle  to a LVDT  as is done
 in the bellows-actuated transmitter.

 Signal Converters -  The 50SF2000 Series  magnetic flowmeter signal con-
 verter is a completely solid-state unit  with integrated circuitry.
 The Converter  is capable of receiving a  low level AC signal either
 directly from  an F&P magnetic flowmeter  or indirectly  via  an F&P  low
 conductivity preamplifier.  This signal  can be converted into an  analog
 DC current,  a  high-frequency  pulse,  or a low-frequency scaled pulse.
 The converter  is suitable for pipe or wall mounting, and as  such,  can
 be provided with a flow rate meter and seven digit counter.   Features
 include automatic dual range, adjustable damping,  and  continuous  and
 automatic quadrature rejection.

 Circular-Chart Electronic Recorder or Indicator -  The  Type 51-1102DC
 circular chart recorder or the  51-1101DC segmental indicator  complete
 with an in-case "Mag/I" Converter  is  designed  to receive the  flow signal
 from various Fischer and Porter magnetic flowmeters  or  from the F&P low
 conductivity preamplifier.  The instrument is  a solid-state, null-
 balance,  servo-operated potentiometer that uses a  unique driving motor
 called a "TORQ-ER" and a contactless  feedback  element called a  "flux
 bridge".   Either instrument is  capable of receiving  one or two process
 variable inputs.  Optional  controllers,  integrators, or transmitters
 can  be included within the  instrument  case.,  Fischer and Porter also
 manufacture many  other primary  devices (e.g.,  turbine meters) and sec-
 ondary devices  (transmitters, receivers, transducers, relays) in both
 pneumatic  and  electronic  form.
SPECIFICATIONS:
               Type 10F1272 Float Actuated Flowmeter
Operating Limits;

Accuracy:
Between 10.16 cm (4 in.) and 76.2 cm
(30 in.) of head at maximum travel

Float travel is within ±0.15 cm
(1/16 in.) of actual liquid travel
                                  241

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Power:
Dimensions:
Weight:
Range:
120 VAC, 60 Hz, Single Phase
Varies according to configuration used
and customer requirements
40.5 kg (90 Ibs)
         Types 10F1275 and 10F1276 In-Stream Flowmeters
 Output:
 Accuracy:
 Power:
 Dimensions:

 Weight:
Type 101*1275:  Can be used on flumes
7.62-305 cm  (3-120 in.) wide and on
rectangular weirs 30.5-305 cm (12-
120 in.) wide.
Type 10F1275A;  Can be used for head
ranges from  0-15.24 cm (0-6 in.) and
0-40.1 cm  (0-15 in.).
Type 10F1275B:  For head ranges from
0-30.5 cm  (0-12 in.) and 0-76.2 cm
(0-30 in.).
Type 10F1276:  For triangular weirs,
Type 10F76A  covers head ranges from
0- to 25.40  cm (0-10 in.) and 0 to
45.7 cm  (0-18 in.).
Electric Time Pulse - DC pulses on
leased or  private pair.
Electric DC  Milliamp Signal - 4 to
20 mADC  over two-wire line.
±20% over  2:1 range  (standard)
120 VAC, 60  Hz, Single Phase
Varies according to  configuration used
and customer requirements

13.5 kg  (30  Ibs)
            10F1430 Series Pitot-Type Magnetic Flowmeter
 Accuracy:
 Repeatability:
 Output:
    Signal
 ±1% for max flow velocity of 0.91 to
 9.42 m/s (3 to 31 fps)  or ±2% for max
 flow velocity of 0.30 to 0.91 m/s
 (1 to 3 fps)                 ?
 0.5% of full scale
 50 or 60 Hz AC, approx 0.2 millivolts
 (rms) per foot (30 cm) per second.
                                    242

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   Reference
Power:
Dimensions:
50 or 60 Hz AC, approx 5 to 6V rms

117 VAC, ±10%, 50 or 60 Hz

Meter - 25.4 cm (10 in.) nominal
inside diameter

Support Suspension Length:
4.5m (15 ft) maximum; 0.3m (1 ft)
minimum
                  SFCC Model 10D1430A Flowmeter
Accuracy (including readout):
Repeatability: ...

Power:


Dimensions and Weight:
±1% Full Scale, 0.91 - 9.37 m/s  (3-
31 fps)

±2% Full Scale, 0.30 - 0.91 m/s  (1-
3 fps)

±0.5% of Full Scale

117 VAC ±10%, 50 or 60 Hz, 17-910 watts
(depending on meter size).

Refer to preceding description of this
flowmeter
               Type 1011940 Plastic Parshall Flume
Free Flow Discharge:
Max Head:
0.38 to 130 MLD (0.1 to 494 MGD)
20.3, 25.4, 45.7, 63.5 and 76.2 cm
                                  (8,10,18,25, and 30 in.)

Weight:                           11.25 to 1350 kg (25 to 3000 Ibs).

            10F1060 Series Plastic Insert Flow Tubes

Accuracy:                       -Within  1% of rate (uncalibrated tubes)

                                 Within ±0.5% of rate (calibrated tubes)

            Types 1451RB and 1453KB Bellows-Actuated
                   Electronic Flow Transmitter,

Range:   (                         5:1 (20% to 100% of max flow rate)

Accuracy:                         ±0.50% of max flow rate (Standard);
                                  ±1.0% of actual flow rate (optional)
Input:                           Differential pressure from flow through
                                  a differential producer.  Bellows
                                  sensing element available in ranges of
                                  0.5m (20 in.)
                                  243

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Output:
Power:
Temperature:

Power:
4-20 mADC into 0-750 ohms.

120 VAC ±10%, 50/60 Hz or 24 VDC

4° to 52°C (40° to 125°F)
120 VAC ±10%, 50/60 Hz or 24 VDC
              Series 50SF2000 Signal Converter for
                       Magnetic Fldwmeters
Input Signal:
Output:
   Electric Analog
    Dual Range Selection
 Accuracies:
 Repeatability;
 Response Time:
 Power:
From any F&P Magnetic Flowmeter.


4-20 mADC into 0-1000 ohms  (0-16 mADC
optional)
10-50 mADC into 0-400 ohms  (0-40 mADC
optional)
Ranges are fixed for ratios of  2:1,
4:1, 6:1, 8:1 and  10:1.  Range  is to
be  specified when  ordering.  Lowest
full scale value is 0.9 m/s  (3  fps).
 (including flow transmitter);   Analog
and/or pulse - ±1/2% full  scale 0.9 to
9.3 m/s  (3 to 31 fps); ±1% of full
scale from  .03 to  0.9 m/s  (0.1  to
 3 fps).
 0.25% of full scale.
 Digital: 1 second
Analog:   1  to 80  seconds,  adjustable.
 (10 seconds  standard)
 117 VAC ±10%,  50  or 60 Hz  ±5%,
 12 watts (max)  @15 VA
              Type 51-1100DC Circular Chart Electronic
                 Recorder or Indicator for Magnetic
                             Flowmeters
 Inputs:

 Output:
    Analog

    Unsealed Pulse
 Accepts signals from all F&P Magnetic
 Flowmeters
 4-20 mADC into 750 ohms or 10
 10-50 mADC into 300 ohms external load,
 10 kHz, 15 VDC, 8 microsec pulse width
 into 2000 ohms or greater.
                                    244

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Accuracy:

Repeatability:
Temperature:
Power:
Weight:
±0,5% of full scale for analog and
pulse outputs on all models including
single and dual ranges.
0.2% of span
4° to 52°C (40° to 125°F)
120 VAC ±10%, 50-60 Hz ±5%, 45 watts
Approximately 18,6 kg (40 Ibs) for
single pen unit.
                                 245

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MANUFACTURER:  CARL FISHER AND COMPANY
               DIVISION OF FOKMULABS, INC.
               529 WEST FOURTH AVENUE
               P. 0. BOX 1056
               ESCONDIDO, CALIFORNIA  92025
               TELEPHONE  (714) 745-6423

PRODUCT LINE:  FLUORESCENT DYES

DESCRIPTION:

This company has long been active in the  chemistry of color and produces
a number of fluorescent dyes that can be  used as tracers in either color-
velocity or chemical dilution flow studies.  Two colors are standard;
fluorescent red  (maximum absorbance point on a spectrophotometer is ap-
proximately 558 my) which is more commonly used, especially if the water
contains some yellow, and fluorescent yellow/green  (maximum absorbance
point  on a spectrophotometer is approximately 494 my) which is recom-
mended for use when the water contains  large quantities of silt.

The dyes appear  to be non-toxic in the  levels used  for flow measurement.
For example, the FDA has established a  level of daily ingestion of
0.75 mg per day  for fluorescent red.  Considering the normal human daily
consumption of water this would equal approximately 370 parts per bil-
lion,  at which concentration the water  would have a bright fluorescent
red color. Instrumental detection limits are around 1 part per billion.

The fluorescent  dyes are available in a number of solid forms including
tablets  (2.5 gm),  cakes  (55 gm), donuts (0.33-1,17  kg), and logs  7.6  cm
 (3 in.) diameter and up to 1.2m (4 ft)  long  (8.6 kg).
 PRICES:
Tablets

cakes

donuts (small)

donuts (large)

logs
$0.07 each (2,600 quantity orders)

 0.90 each (5,000 quantity orders)

 4.75 each

10.00 each

24.00 per foot
 COMMENTS:
 These dyes appear suitable for a number of storm or combined sewer flow
 studies.  The manufacturer will offer specific information on such
 applications upon request.
                                    246

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 MANUFACTURER:
 PRODUCT LINE:
 DESCRIPTION:
     TECHNOLOGY, INC,                         .  ' .,
4250 EAST BROADWAY ROAD
PHOENIX, ARIZONA  85040
TELEPHONE  (602) 268-8776

TURBINE FLOWMETERS OF VARIOUS CONFIGURATIONS PLUS A
COMPLETE LINE OF SECONDARY INSTRUMENTATION INCLUDING
SIGNAL CONDITIONERS, PULSE RATE CONVERTERS, FLOW RATE
MONITORS, ETC.
 Flow Technology,  Inc.  manufactures "standard line" axial-turbine flow-
 meters in sizes from* 0.6 cm (1/4 in.)  to 0.6m (2 ft)  with standard
 ranges of 10:1 which can be extended to as much as 250:1 in some cases.
 They also manufacture a tangentially-driven  turbine,  the "omniflow"
 which is  capable of measuring extremely low  flow rates.   Neither of
 these appears  suitable for wastewater  applications, and  they will not
 be described further..•'....

 Flow Technology manufactures point velocity  sensing elements called
 "Turbo-Probes".   The "Turbo-Probe" family of turbine  flow transducers
 utilizes  a small  axial-flow turbine sensing  element positioned  in the
 flow stream of a  large duct,  pipe,  or  channel by means of a strut.
 The sensing element is a small,  freely-suspended turbine flowmeter
 unit within its own open-ended cylindrical capsule.   As  this turbine
 turns under the force  of the flowing fluids,  its rotation produces a
 series of electrical pulses in a pickoff located in the  strut.   The
 pulse rate or  frequency of  this  electrical signal  is  directly pro-
 portional to the  velocity of the fluid passing  through the'capsule.
 This pulse output can  be fed to  appropriate  electronics  to count,
 totalize,  or display the flow velocity of rate  in  various  engineering
 terms - feet per  minute,  gallons  per minute, meters per  second,  cubic
 meters per hour,  etc.   This  output  can also  interface with industrial
 process control systems  or  on-line  computers.   This family of flow-
 meters has  found  applications both  as  portable  insertion probes  and as
 permanently-instailed  units.  Figure A depicts  a typical  configuration.

 An outstanding feature of the "Turbo-Probe" series is the  economy
 achieved when it  is necessary to make  flow measurements  in pipes,:ducts,
 or channels  of very large size.  The exorbitant  cost of full-bore tur-
bine  flowmeters far outweigh their  favorable high-accuracy charac-
 teristics  in such applications.  The response of such large
 turbines  can be low because of the high mass of  the rotors.  However,
 in such applications, a  "Turbo-Probe"  installation with its small tur-
bine  can  result in considerable cost savings at little sacrifice of
accuracy and considerable gain in response.  If the velocity profile
in the flow  channel is known, the fluid velocity data can be directly
                                  247

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related to flow volume.  Absolute volumetric flow accuracies of
+0.5 percent have been achieved.  The accuracy of velocity measure-
ments are on the order of ±0.25% under field conditions.
                              Figure A

 "Turbo-Probe" units  can be fabricated from a wide variety of materials
 capable of withstanding the most difficult industrial  environments.  A^
 retractable version  of this flow velocity sensor called  "Retracto-Line"
 is also offered for  use in large diameter pipelines.

 Secondary Elements - Model LFP-200 is a low flow, offset signal  condi-
 tioner.  Turbine flowmeters designed  for low flow rates  exhibit  a  linear
 frequency output as  a function of flow rate, but also  exhibit  a  zero
 offset that appears  as a non-linearity with a standard flow rate monitor
 or flow totalizer.  Flowmeters designed for higher  flow  rates  also
 exhibit this zero offset characteristic when there  is  an increase  in
 the viscosity of the fluid being measured or when  the  flow  range is
 extended below the normal minimum for the particular design.

 The LFO-200 is designed to correct this zero offset by injecting into
 the flowmeter output pulse signal a predetermined  frequency -  dependent
 upon the design of the flowmeter - that allows the flow-versus-frequency
 characteristic curve to intersect the zero point,  thus eliminating the
 zero offset.  Because turbine flowmeters have a minimum flow  rate  and
 do not respond down to zero flow rate - there is  a point where flow
                                    248

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 exists hut the turbine rotor stops or becomes highly non-linear in its
 rotation - the LFO-200 incorporates a circuit to cut off the frequency
 output at a predetermined minimum output frequency.   Because of the cut-
 off feature, there is no output from the LFO-200 when the rotor is
 turning below a given rate  or when the rotor is stopped.   The LFO-200
 therefore increases the accuracy of low flow indications and permits
 the use of less-expensive frequency-to-analog flow rate monitors and
 flow totalizers.   The LFO-200 is a solid-state unit  normally packaged
 in a heavy-duty steel JIG box with input,  output, and power supply con-
 nections made through MS.-type connectors.   Other types of enclosures
 and connectors are available on special order.

 Model LFA-300 is  a range extending amplifier.   Turbine flowmeters with
 normal pickoffs experience  a magnetically-induced drag on the turbine
 rotor.   This drag force causes severe non-linearity  at very low flow
 rates.   To eliminate this low-flow rotor drag,  an "active" pickoff coil
 must be used.   The Range Extending Amplifier LFA-300 is the necessary
 electronic unit for use with such an active pickoff  and supplies an
 amplified pulse output with the same frequency  as the input signal.
 The LFA-300 can extend the  operational range of turbine flowmeters from
 their normal 10:1 ratio up  to a ratio of as  much as  250:1.   In the low
 flow ranges, because of the zero offset phenomenon,  the output will be
 non-linear;  however,  it will be a repeatable non-linearity.   The
 LFA-300  is  a solid-state unit normally packaged in a heavy-duty  steel
 JIG box with input,  output,  and power connections made through MS-type
 connectors.
SPECIFICATIONS:

     "Turbo-Probe"
       Model FTP-A
Velocity range span     1.5-30.5 m/s (5-100 fps)
Velocity range ratio

Turbine head dimensions

Linearity

Repeatability
10:1 standard

1.9 cm (3/4 in.) dia &
  length

±0.5%

up to ±0.1%

   Model LFO-200
    Model FTP-B

0.09-30.5 m/s (0.3-
  100 fps)

10:1 standard

3.2 cm (1.25 in.)
  dia & length

±0.5%

up to ±0.1%
Signal Input:


Signal Output:
         Frequency range - 1 to 3000 Hz.   Input
         level - 5 to 20V pulse

         Frequency - Input frequency from flow-
         meter plus injection frequency
                                 249

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Internal Adjustments:


Power Requirements:
Dimensions:



Input:

Output:

Power:
Dimensions:

COMMENTS:
       Output level - .5V peak-to-peak
       pulse
       Offset Frequency Range - 0.5 to 25 Hz.

       Cutoff Frequency Range - 1 to 25 Hz.

       115V 60 Hz.  Less than 5 watts
       15.4x10.2x7.6 cm (6x4x3 in.)
Model KFA-300
       1 to 3000 Hz from turbine flowmeter
       active pickoff
       10V peak-to-peak pulse into 10K load,
       frequency identical to input frequency

       24 VDC 50 mA, 115V 60 Hz optional

       15.4x10.2x7.6 cm  (6x4x3 in.)
These  turbine point velocity sensors may find some application in
attended use in wastewater flow  surveys.  The range-extending option
appears attractive, and  their  sensitivity should  allow velocity pro-
filing and  the  like to be accomplished  fairly well.  They  do not appear
suitable for unattended  use or fixed  installations, however.
                                   250

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                                         (212)   227-6668
 MANUFACTURER:   FLUMET  CO.
                P.O.  BOX 575
                WESTFIELD, NEW JERSEY
                N.Y.  OFFICE:   TELEPHONE

 PRODUCT LINE:   PALMER-BOWLUS  FLUMES

 DESCRIPTION:

 FLUMET manufactures  a  "trapezoidal throat venturi weir" that has evolved
 from  the Palmer Bowlus  flume.  It is comparable to a Parshall flume in
 accuracy and in minimum restriction to flow, but the throat area design
 avoids the necessity for the  rectangular approach section.  The trape-
 zoidal section  is hydraulically like circular channel flow and
 establishes a usable energy head.  The Flumet units are three-piece
 flumes designed for  installation where through-type manholes exist on
 normally sloped lines.   All Flumet flumes will pass solids up to
 7.62  cm (3 in.) spherical equivalents.

 Where sewers exist,  and  to permit surveys, the standard hexagonal units
 can be placed under  flows of  50 percent depth.  The flume is placed near
 the manhole out-fall.  The channel should be "U" shaped, with side walls
 up to 90 percent of  the  line  diameter; if too shallow, temporary walls
 can be created.  To  install,  the base (or sill casting) is dropped in
 place, and then the  side walls are locked in and dropped back against
 the walls at a  controlled angle; a template is provided for checking.
 Grouting is seldom'required,  and small leaks are often quickly sealed
 by the fibrous  particles of waste flow, due to the ribbed back design.

 Use of a stilling well and large area float will produce maximum head
 accuracy.   The  flume is  compatible with various secondary metering
 instrumentation.

 Flumet's eccentric flume reducer is designed for large conduits (waste
 collector lines) whose diameter is based on future flows,  but where,
 initially, lower-volume  flows must be metered.  The Flumet split ec-
 centric reducer can be installed, then dismantled and removed later,
under flow.   These modules are molded of acid-resisting, glass resin
 and fiber laminates, made in 68.6 centimeter (27 inch)  lengths to pass
 through manhole frames.  Field installations can be made in 1-1/2 to
 2 hours.
SPECIFICATIONS:

Accuracy:
Sizes:
                                 3% (optimum)

                                 15.2 to 76.2  cm (6 to 30 in.)  for
                                 standard sewer piping.
                                  251

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Flow Capacities:

Length:
Weight:
From 1.32 MLD (0.350 MGD) for 15.2 cm
size to 53.0 MLD (14 MGD) for 68.6 cm
sizes
27.9 to 132 cm (11 to 52 in.)
5.4 to 79.4 kg (12 to 175 Ibs)
PRICES.:  Approximately $200-$500 for a basic insert flume.
COMMENTS:
Palmer-Bowlus type  insert flumes were thoroughly discussed in  Section VI
and no further comments will be made.
                                   252

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MANUFACTURER:
PRODUCT LINE:
THE FOXBORO COMPANY
FOXBORO, MASSACHUSETTS  02035
TELEPHONE  (617) 543-8750
PRIMARY DEVICES - TARGET, ELECTROMAGNETIC, AND TURBINE FLOWMETERS.

SECONDARY DEVICES - DIFFERENTIAL PRESSURE TRANSMITTER, MERCURY-TYPE
FLOWMETERS, LIQUID LEVEL TRANSMITTERS, AND VARIOUS FLOW INTEGRATORS,
RECORDERS, ETC.

DESCRIPTION:

Foxboro is a leading, worldwide supplier of instruments and systems for
process management and control.  It has more than 60 years of specialized
experience in the production of measurement, recording, and control de-
vices and systems designed to measure, handle, and control liquid flows,
liquid levels, pressure, etc.  This varied line of instrumentation
ranges from meters, recorders, and indicators to complex digital con-
trol systems fully equipped with computers and other data processing
equipment.

Primary Devices

Target Flowmeters - Foxboro manufactures both pneumatic and electronic
target flow transmitters.  These transmitters produce repeatable force-
balance measurement and transmission of both clean fluids and fluids
of a heavy, conductive and non-conductive viscous nature (such liquids
include slurries up to 1500 psi, even in high viscosity regions where
pipe Reynolds numbers are 2000 or less).  Because target-type devices
are generally unsuitable for storm or combined sewer flows, they will
not be discussed further.

Electromagnetic Flowmeters - Based on more than 16 years of experience
in magnetic flow measurement, Foxboro has recently introduced completely
redesigned electromagnetic flow instruments.  Nearly any electrically
conductive liquid (up to 160°C) can be accurately metered (e.g.:  dirty,
viscous, corrosive, or abrasive slurries; solids bearing; turbulent;
etc.).  Both industrial and municipal water and waste treatment plants
utilize Foxboro magnetic flow systems.  Typical applications include
plant-effluent, activated sludge, raw sewage, etc.

Representative of this product line is the Series 2800 flow transmitter,
which operates at line sizes of 2.54 to 30,5 cm (1 to 12 in.)*.  The
*  Other transmitters are available for line sizes up to 122 cm (48 in.)
                                   253

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magnetic flow transmitter responds to liquid velocity only.  It gen-
erates an AC voltage directly proportional to fluid velocity and, hence,
volumetric-flow rate.  The transmitter is unaffected by process varia-
tions in density, viscosity, line pressure, vibration, or temperature.
The transmitter is accurate with liquids as low in conductivity as
2 micromhos per centimeter.  System accuracy to ±0.5% of full scale can
be achieved.  The unit operates in horizontal, vertical, or any angular
position as long as the electrodes are in the same horizontal plane.
Transmitters are available with flow tubes of fiberglass or stainless
steel lined with TFE or polyurethane.  Coils are external to the flow
tube for accessibility and protection from process and environmental
conditions.

The 2800 Series transmitter contains no converter-type circuitry but can
be equipped with the Foxboro 696A Series converter to obtain direct
totalization of liquid flow.

Turbine Flow Transmitters - These devices measure volumetric flow.  The
liquid stream passes through a rotating multi-blade rotor.  As the rotor
turns, a pickup coil induces a pulse of voltage (as each blade passes).
The pulse rate is proportional to volumetric flow rate, each pulse being
a measure of a discrete volume of liquid.  Because it is generally con-
sidered to be unsuitable for sewage and waste-water applications, the
turbine meter will not be discussed further.

Secondary Devices

Force-Balance Transmitters - This device uses the Foxboro-developed
differential pressure cell transmitter mechanism to measure the pressure
differential produced by any one of a variety of primary devices (e.g.,
venturi tubes, orifices, etc.) and transmits to remote receivers
(pneumatic or electronic) any variable which is a function of pressure,
flow, liquid level, density, or temperature.

Mercury-Type Flow Meter - This device gives precise metering of liquid,
steam, and gas flows at pressures up to 2500 psi, and is suitable for
use with a number of differential-pressure type primary devices.  They
are normally equipped with 30.5 cm (12 in.) circular chart recorders.

Flow Integrators - These devices indicate the number of gallons or other
units of fluids passing through a specific point in a given time period.
The quantity is shown on a 6- or 8-digit counter.  They are available
for simple integration, remote integration in both electronic and
pneumatic systems, pulse duration, and continuous integration.  They
also have provisions for batching, switching, etc.
                                   254

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Electromagnetic Flow-To-Current Converter - The 696A Series converter
accepts the generated voltage from the electromagnetic flow transmitter
and transmits a standard DC signal to electronic receivers.  Outputs
can be either 10 to 50 mA or 4 to 20 mA.  The signal is directly pro-
portional to (linear with) flow rate.  A scaled pulsed output is also
available for direct flow totalization in engineering units.

Other Electromagnetic Flow Measurement Instruments - Other Foxboro
instrumentation in this product line includes the 9650 Series Dynalog
Recorder, which receives and records the generated voltage output of
the transmitter on a 30.5 cm (12 in.) circular chart or provides large
dial indications.  Foxboro also manufactures a wide line of pneumatic
and electronic controllers, recorders, integrators, and counters.

Liquid Level, Density, and Interface Instruments - Foxboro instrumenta-.
tion provides various approaches to liquid level measurement.  Included
are air bubble systems, submerged diaphragm boxes, float and cable sys-
tems, direct-connected static head systems, diaphragm and mercury   ••  .
manometer elements, etc.

COMMENTS:

The devices offered by Foxboro have been thoroughly discussed elsewhere
and will not be further described here.
                                 255

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MANUFACTURER:  GM MFG. AND INSTRUMENT CORPORATION
               2417 THIRD AVENUE
               NEW YORK, NEW YORK  10451
               TELEPHONE (212) 665-1601

PRODUCT LINE:  CURRENT METERS AND ACCESSORIES

DESCRIPTION:

This firm manufactures a number of hydrographic current meters and
accessories, a few of which will be described here.  "GEMWARE" current
meters are supplied with light-weight propellers, specially shaped to
operate at all rated water flows with a minimum of friction, to ensure
highest registration accuracy.  Their hydrodynamic forms were developed
after many towing tank trials.  They are electrical switch-type meters,
producing either a -mechanical contact by a gear or a frictionless con-
tact by a magnet.  The contacts may be registered by earphones, buzzers,
blinking lights, digital counters, digital printers, strip chart event
recorders, etc.

For deep or fast water, the current meter is usually suspended by its
electrical cable with a hydrodynamic weight at the end.  For shallow
water operation, it may be attached to a wading rod.  When using current
meters for measuring water flow in conduits or pipes, etc., adjustable
holders for mounting can be furnished.  Differently pitched, hydro-
dynaraically shaped, and vane type propellers have been specifically
developed for measurements of slow, medium, and fast currents.  They
are of lightweight metal alloys, surface treated to better withstand
corrosive action, and are carefully hand finished and polished.  Each
is individually tested with its current meter and furnished with a
calibration certificate; with a graph, an accuracy of 0.025% may be
expected.  The propeller shafts rotate on precision bearings and almost
all meters are sealed or protected against water entrance, either
mechanically or by an oil bath.  "GEMWARE" current meters are shipped
in sturdy, compartmented, wooden carrying cases with accessories, spare
parts, and tools.

The No. 232WA060 "GEMWARE" Mechanical Contact Current Meter, with a
25 cm (10 in.) pitch x 12 cm  (4.7 in.) diameter contoured propeller
can measure flow rates .over a range of 0.2 to 5 m/s (0.6 to 17 fps).
Exchangeable gears provide electrical contact for either 10 or 20 turns
of the propeller.  On special order, other gears can be supplied to
make contact for each 5 propeller revolutions or to indicate reversal
of flow direction.  The meter may be affixed to a wading rod or may be
cable suspended with a self-aligning, hydrodynamic-shaped weight and
tail vane.
                                  256

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The N0.232WA240. "GEMWARE" Magnetic Contact Current Meter (Figure A)
is the modern concept of a hydrodynamically constructed meter which is
reliable for water speed measurements in rivers, dams, reservoirs, etc.
It is streamlined and watertight and has a hermetically-sealed,
magnetically-attached switch electrically connected to a watertight
jack for the plug-in electrical cable.  There are no exposed gears or
components to wear or corrode nor can the electrical contacts become
fouled, as with the Price current meter.  It may be used in silt-laden
waters without damage as all the components, except the propeller, are
                            Figure A


sealed within the one-piece, machined housing.  The propeller can be
supplied with a special coating to improve its hydrodynamic efficiency
and resist the possibility of corrosion.  This meter is extremely
sensitive to waters flowing at all speeds and accurately measures flow
over a range of 0.2 to 5 m/s; its 25-cm pitch, lightweight propeller
is supplied with an individual calibration to assure accuracy for flow
calculations.  It is reliable and is unconditionally guaranteed as to
quality and workmanship.  The meter is furnished in a sturdy, hinged-
cover, wooden case with compartments for the current meter, spare
parts, 10m (33 ft) long reinforced lowering cable, lubricating oil,
and tools.  The complete apparatus with accessories and storage case
weighs 6 kg (13 Ibs); the case dimensions are 35x21x14 cm (14x8.5x
6 inches).

The No. 231WA300 "GEMWARE" Current Meter is an improved Ekman type
meter.  This is a mechanical instrument and is operable at any depth
by the use of messengers.  The patented split bearing system allows
fastening of one or more meters at any point on the wire.  As it is
messenger operated, it can even be placed on the wire between water
bottles or other messenger-actuated instruments.  Accidental damage
is minimized by rugged construction and the use of metal guards to
protect moving parts.  All materials used are non-magnetic and the
entire instrument is silver plated.  A spring-loaded, flared, split
                                 257

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tube is provided to lock the propeller until ready to start the meas-
urement.  At that time, a messenger is dropped down the wire to actuate
the split tube release which rotates, horizontally, about 45 degrees,
giving the propeller a short push to overcome any starting inertia
when measuring very low speed currents.  After a predetermined time
period elapses, a second messenger is dropped to release a spring-
tensioned short rod, which then also rotates on a horizontal plane
and passes between the propeller blades to stop further rotation.
With every 33 revolutions of the propeller one metal ball falls through
a tube in the dial counter gear box and into a trough on a freely-
moving, pivotally-mounted, plastic coated, permanent magnet.  The ball
rolls down the trough and drops into one of the compass box compartments,
numbered from 0 to 35.  Compartments 0 and 18 are fixed parallel to the
axis of the propeller shaft; the magnet always orients to the North.
The ball storage tube has a reservoir at the top, closed by a screw cap.
Generally 50 percent of its capacity is filled with balls of one color
and the balance filled with differently colored balls.  Using balls of
two different colors assists in determining the approximate time a
major underwater directional current change may take place during the
measuring cycle.  One can readily ascertain the mean current direction,
and its variations, by noting the number and locations of the metal
balls in their respective compartments.  The meter is 30 cm (12 in.)
high and 61 cm (24 in.) long  with tail fin attached.

The No. 232WA080 Shallow Water Current Meter, Price Pattern, is made
to the specifications of the U.S. Geological Survey.  Most of the com-
ponents are fabricated from brass and nickel-plated for protection and
good appearance.  This instrument is also made in a pygmy size for use
in shallow waters or restricted areas.

PRICE:

Prices range from around $275 for a Price meter to $520 for a magnetic
contact current meter.

COMMENTS:

The use of current meters was thoroughly covered in Section VI and will
not be commented on here.
                                  258

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MANUFACTURER:  HINDE ENGINEERING COMPANY OF CALIFORNIA
               P.O. BOX 56
               SARATOGA, CALIFORNIA  95070
               TELEPHONE (408) 378-4112

PRODUCT LINE:  PALMER-BOWLUS S.UMES

DESCRIPTION:

The Hinde Engineering Company manufactures "Accura-Flow" insert flumes,
which are generally of the Palmer-Bowlus type.  These flumes are adapt-
able to many unpressurized flow measuring applications, including
sewage and industrial wastes in open channels or in certain cases, pipe-
lines.  Some can also be installed on a temporary basis to verify flow
trends.  Some of its most important characteristics are reasonable
measurement accuracy, low energy loss, minimum restriction to flow, and
ease of installation in existing conduits, operation, and maintenance.

The flume is installed in either a "U" channel or circular conduit sec-
tion with the flume set level at the proper location such that flow
through the flume will be laminar, with a slight "ponding" effect just
ahead of the flume.  If it is desired to measure low flows in a large
channel or conduit, this may be accomplished by setting the Palmer
Bowlus flume in a channel liner.  This arrangement permits accurate
measurements where the system flow will gradually increase over a long
period of time.  Initially, with a small flow rate, the proper size of
flume is selected and set in a liner of correct size.  Then, as the flow
range increases up to the maximum design of the particular size of
Palmer Bowlus flume, the next appropriate size is selected and installed.
This series of flume modifications permit proper flow measurement up to
the design limit of the channel or conduit.  Any abnormal flows such as
storm water will overtop the flume insert and liner without detrimental
effect.                     ,

Either on-site or remote registering secondary devices may be used with
these flumes to give permanent records of flow rates and totalized vol-
ume.  Stilling wells, scow floats, and bubbler systems have been success-
fully used when employing on-site recorders.

The basic Accura-Flow flume (without modifications) is constructed of
stainless'steel and is a one-piece integral unit.  Some examples of the
various configurations and applications of this flume are as follows:

     •  A typical manhole installation (Figure A).

     •  A flat-bottom flume for measurement in an open trapezoidal
        channel (Figure B).
                                   259

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     2 D,
    Z.5D2
     MIN
— 	 is.

FLOW \
N!
—

^
L/
7
k
r
                                   D,


                                   02
            ORIGINAL PIPE OR U-SHAPED
            CHANNEL DIAMETER

            ACCURA-FLO CHANNEL
            REDUCER DIAMETER
                                 PROVIDE ANCHORS
                               — TO SIDEWALL.IF
                                 /REQUIRED

                                   0.5 Dz

                                    METERING ZONE 0.5DZ
  FILL WITH LOW
STRENGTH CONCRETE
   ACCURA-FLO
  PALMER BOWLUS
 METERING
FLUME
                         ACCURA-FLO
                        CHANNEL REDUCER
                               PROVIDE MIN
                             SLOPE REQUIRED
                              FOR RUN-OFF
                                             ALTERNATE VIEW
                                              FOR MANHOLE
                            Figure A
                               260

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Figure B
Figure C
                      Figure D
                        261

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        A flume built into a channel liner fitted with end plate
        adaptors.  This design is intended for use in measuring
        low flows in an existing channel (Figure C).

        A dual channel assembly, each having a flume of different
        capacity.  The two channels measure seasonal flows on a
        selective basis (Figure D).
SPECIFICATIONS:

Accuracy:
Submergence
Maximum Recommended Slopes and
Maximum Discharge Capacities:
                           Comparable to that of Parshall or other
                           types of venturi flumes.  Experiments
                           have indicated that, within the normal
                           range of flows (from less than 10% to
                           90% of pipe  capacity), the errors are
                           less than 3%.

                           Less than 0.85 D (pipe diameter or
                           channel width).
    Diameter
   15.2
   20.
   25.
   30.
   38.
   45,
   53.3
   60.0
   68.8
,3
.4
,5
.1
,7
in.
 6
 8
10
12
15
18
21
24
27
                     Max.  Slope
2.2
2.0
1.8
1.6
1.5
1.4
1.4
1.3
1.3
                  Max.  Flow Capacity

                     &/s     cfs
9.9
19.8
35.4
55.2
96.1
151
219
338
416
0.35
0.70
1.25
1.95
3.40
5.35
7.75
11.95
14.70
                                  262

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MANUFACTURER:
PRODUCT LINE:
DESCRIPTION:
HOWELL INSTRUMENTS
3479 WEST VICKERY BLVD.
FORT WORTH, TEXAS  76107
TELEPHONE (817) 336-7411

SOLID STATE DIGITAL INDICATORS, COUNTERS, TOTALIZERS,
RECORDERS, ETC.
Howell Instruments manufactures a number of precision instruments that
might be used as secondary devices in a total flow measuring system.

H600 Digital Indicator - The H600 Digital Indicator is a compact, ac-
curate, and reliable instrument that displays outputs in engineering
units from flow meters (square root), frequency transducers, linear
signal sources, or signal transmitters (10-50 ma, 1-5 volts, etc.).
The display, which uses ,0.65-inch characters, includes four digits .of
data, an out-of-range caption, and an engineering units identification
caption.  This panel-mounted instrument has a low power requirement,
over 120,000 hours MTBF (does not include readout lamps), and low cali-
bration drift.  Options include BCD output, analog output, 12- or
28-volt DC power, alarm limit and an alternate case.

H2300 Portable Digital Indicator - The H2300-1 Portable Indicator uses
a rechargeable power pack with the H600 Digital Indicator to provide
a completely self-contained instrument.  The H2300 can be operated as
a bench-type instrument from the AC power line even when the power pack
has been completely discharged.  In addition, the H2300 can be charged
indefinitely without harming the power pack.

Multipoint Digital Indicator - The Multipoint Digital Indicator is an
enclosed, portable unit that accepts up to 12 two-wire inputs using
Howell's H600 Digital Indicator.  The indicator uses either pushbutton
or toggle switches to select a single input.  Switches are identified
either by an engraved number on the pushbutton or switch identification
cards.  Options include 12- or 28-volt DC power and adjustable alarm
limits.

H603B Totalizer and H603E Batch Counter - Adjustable scaling (meter
factor) is featured in this new series of totalizers and batch counters.
Both the totalizers and batch counters count from switch closures,
pulses, AC inputs, and voltage transitions; they also include adjust-
able scaling for a direct engineering unit readout.  Plug-in components
permit field modification to change the type of input accepted.  The
totalizer and counter accept input levels as low as 10 millivolts rms
and frequencies up to 50 KHz.  A seven-segment, half-inch high, gas
discharge module provides the display.  The H603B and H603C (only
                                  263

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difference is in case) totalizers include a six-digit display with
movable decimal point.  The H603D and H603E batch counters (only dif-
ference is in case) have a five- or six-digit display with movable
decimal point and include thumb-wheel switches that present the desired
batch count.  When the displayed number reaches this preset count, a
lamp and relay both operate.

The totalizers and batch counters include as standard equipment a
counter reset button and a "run" lamp that lights during a counting
operation.  The totalizers and counters can also be started and stop-
ped by a remote switch closure or TTL signal having a minimum duration
of 50 msec.  The meter factor is set using binary rocker arm switches.
These switches divide the input by any whole number from 1 through 4095
before display.  Options are available to expand the division feature
(through 65,535) to double the readout to count both positive and nega-
tive voltage transitions, and to multiply the input by 1.0000 to 1.9999
which, when combined with the divider switches, can adjust the input to
read out input/display ratios that are not whole numbers.

The H603B totalizer and H603D batch counter are housed in a panel-
mounted case that permits the chassis to slide out the front of the
case for removal or adjustment of meter-factor switches.  No tools
are necessary.  The H603C totalizer and H603E batch counter are also
housed in a panel mounted case; however, their chassis are not mounted
on slides.  The front bezel snaps on, covering the chassis mounting
screws.  Top and bottom covers are removable to obtain access to all
components.  A separate temperature compensator module, compatible
with the totalizers and batch counters, is available to compensate for
specific gravity changes in flow measuring applications.

H490 Digital Data  System - The H490 Digital Data System is a flexible,
compact system that measures inputs from signal conditioners or trans-
mitters, and other linear sources.  Data are displayed and printed
directly in engineering units.  The H490 System can operate from two
different sensors  and can monitor from 10 to 100 points.  Scanning
modes include (a)  continuous monitoring of either one or all points
and  (b) manually initiated scanning of all points one time.  Points  can
be omitted from the scanning sequence in groups of ten.  A timed-start
feature permits unattended system operation by automatically initiating
a print sequence at every 10, 20, 30, or 60 minute interval.  The
standard printout  consists of a six-digit time group, two digits of
point identification, and four or five digits of data together with
appropriate range  identification.  As an optional feature, up to  two
limits are available.  They  can be programmed as high or low and
adjusted  to operate an alarm relay at any point in the readout range.

H4200 Digital Data System -  The H4200 Digital Data System is a fast-
reading, high-input capacity system that measures signals from signal
conditioners or transmitters, and other linear sources.  Data are
                                   264

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displayed and printed directly in engineering units.  Catalog modules
are combined in-the H4200 to provide (a) four recording options,
(b) speeds of up to 20 points per second, (c) up to 1000 inputs,
(d) either one Or two individual limits per point, (e) up to four dif-
ferent ranges, and (f) point omission either singly or in groups of
10.  The H4200 system generates output data that are recorded on a
line printer, an electric typewriter, or a teletype unit.  Two types
of out-of-limit detection and alarm devices are available.  One type
provides one limit, either high or low, for each point.  The other
type offers two limits - high and low, high and higher, or low and
lower - for each point.  Limits are digital, can be either positive
or negative, and are adjustable throughout the range of the system.
Scanning modes include (a) continuous monitoring of one point, (b) con-
tinuous scanning of all points, or (c) manually or automatically ini-
tiated single scan of all points.  Any of these modes can be initiated
either locally or remotely by an external switch closure.  Points can
also be manually selected and printed one point at a time.

H4500 Digital Data System - The H4500 Digital Data System uses a digital
processor (computer) to control the system.  Ability to readily produce
a custom software, package has enabled Howell to design standard hard-
ware that can be tailored to a great variety of customer needs.  Opera-
tional modes, types of signals measured, the display and printout
format, and any computational arid correctional operations performed in
the computer can be designed to customer requirements.

The H4500 System measures and records data in applications where a
number of points and/or parameters must be accurately recorded in engi-
neering units.  This system is ideally suited to applications involving
measurement of nonlinear signals or measurements requiring corrections
and computations dependent on other parameters.  The H4500 can measure
inputs directly from all industrial type sensors including speed and
flow types (frequency), transducers, strain gages (pressure, torque,
load, displacement, etc.), and other transducers having a voltage,
resistance, or frequency output.  The H4500 can also accept signals
from signal conditioning transmitters (10-50 ma, 4-20 ma, 1-5V, etc.)
or provide state indications of contact closures.  A typical H4500
System consists of a freestanding equipment cabinet, which includes a
digital processor; a teletype terminal; and one or more display modules.
The system can accommodate up to 1024 inputs, scan up to 50 points per
second, and detect out-of-limit points.  The remote digital display
reads out both measured and computed data.  While the Teletype is not
the only input-output device available with the H4500 System, it offers
a satisfactory compromise between versatility and economy in most ap-
plications.  The teletype terminals*s function is two-fold.  First, it
operates as a printer to record data in any of the various operational
modes.  Second, keyboard commands to the digital processor initiate the
                                  265

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operational modes, omit points from scanning, change limits, store point
messages, and even change scaling and zero offset of points on an
individual basis.

Optional features include alarm limits, printed English language
messages to simplify point identification, computed and corrected values
(square roots, logs, differential measurements, etc.) based on input sig-
nal measurements, and remote readout(s).  Other options include a CRT
display with or without an input keyboard, a high speed line printer,
separate alarm message printer, analog outputs for trend recording,
timed start for unattended installations, computer interface, and mag-
netic tape recording equipment.
                                  266

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MANUFACTURER:  INTEROCEAN SYSTEMS, INC.
               3510 KURTZ STREET
               SAN DIEGO, CALIFORNIA  92110
               TELEPHONE (714) 299-4500

PRODUCT LINE:  CURRENT METERS^, WAVE AND TIDE GAGES

DESCRIPTION:.

As its name  implies, InterOceah Systems offers a wide line of sensors
and instrumentation initially designed for oceanographic applications.
Several of the products they market could find use in the wastewater
area, however.  Their current meters include the Ekman-Merz, ducted
Impeller, Savonious rotor, and electromagnetic types.  These meters are
available as self contained units with analog or digital self-recording
'or as remote units with real-time readout.  Of the current meters just
mentioned, only the electromagnetic self-recording Model 195 will be
described.

Model 195 Current Meter - The Model 195 Current Meter incorporates the
inherent advantages of a solid-state, no-moving-parts sensor with many
optional sensors for environmental monitoring as well as automated
instrument recovery.  A unique data preprocessing circuit and flexible
data formatting are combined with a computer-compatible digital cas-
sette data recording system.

The entire instrument may be installed below the water surface on any
structure or it may be implanted on the bottom.  Being out of sight
drastically reduces its vulnerability to vandalism and accidental
mishaps.  The current speed, direction, time and optional parameters
may be recorded for periods up to 90 days (or one year, optional).
At the end of the monitoring period, when the operator replaces the
digital tape cassette and batteries and cleans the sensor head, the
instrument is ready to be deployed again.  The data recorded on the cas-
sette are ready for transcription or direct computer data processing.

The current sensor consists of an electromagnet and two electrodes en-
capsulated in a rugged, waterproof anti-fouling neoprene assembly.  The
electromagnet produces a magnetic field.  When the water passes through
the magnetic field, a potential gradient is produced which is sensed by
the electrodes.  The voltage representing the magnitude of the water
current is fed into the solid state signal processing electronics,
digitized, and recorded on the internal digital cassette magnetic tape
recorder.

STG/100 Wave and Tide Gages - These gages are used to monitor waves and
tides over wide ranges with extremely high precision.  The instrument
can be used to sense rapid or gradual level fluctuations in lakes,
                                  267

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rivers", estuaries, harbors, and ocean coastal zones.  The basic instru-
ment contains a sensitive, temperature-compensated, multi-turn Bourdon
tube pressure element.  A patented optical.system senses the pressure
signal, eliminates hysteresis and provides a wide dynamic operating
range with no sacrifice in high precision.  Both remote and self-
contained models are available.  The remote model has a cable connected
to a remote power supply, data display, and recording station.  The self-
contained recording model is available with either a miniature strip
chart recorder or a digital magnetic tape cassette.  The response time
of the instrument is adjustable by using one of a variety of filters
available.  This feature permits optimum use of the basic instrument
for the study of phenomena ranging from short period wind waves through
tides.

A light beam focused through a unique grid system  is used to sense very
small changes in rotation of the freely suspended  Bourdon tube.  An
electronic servo network nulls the light beam signal to provide a highly
accurate and linear output over a single small scale.  The grid system
also provides for multiple scale nulls so  the dynamic range of the in-
strument is greatly extended without affecting the accuracy.  The
instrument can be attached to existing or  specially provided structures,
or lowered directly to  the bottom.  Since  the instrument functions as a
multiple null detector, it is ready for use without any adjustments
independent of the water  depth into which  it has been placed.  Accuracy
is independent of water depth.

SPECIFICATIONS:
 Model 195 Current Meter
 Sensor
    Type:
    Range:
    Accuracy:
    Resolution:
 Compass
    Type:
    Range:
    Precision:

 Recorder
    Type:
    Capacity:
Electromagnetic
0.03 to 3 m/s (0.08 to 10 fps)

±2% Full Scale
0.03 m/s (0.08 fps)


Permanent Magnet

0 to 360°

±5°


Digital, Cassette

2.7 x 106 Bits
                                    268

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    Precision:
    Record:

    Format:

 Clock
    Type:
    Accuracy:
 Dimensions
    Sensor:
    Pressure Case:
    Weight:
 Model ST6/100 Wave and  Tide Gage
    Range:
    Precision:
    Wave Filter:

    Clock:

    Data Interval:

    Operating Time:

    Operating Depth:
    Power:

    Pressure Case:
           12 Bit Words
           Identification Word-Time-Speed-
           Directiori-Options
           Programmable|  Instantaneous,  High/
           Low/Mean,  High Density             • '  •

           Digital, Solid State
           ±0.01%

           2.5 cm (1  in.)  OD x  18.5  cm  (7.25 iri.)L
           16.5 cm (6.5 in.) OD x 84 cm  (33 in.) L
           10 kg (22  Ibs)  in air

           30m (98 ft)
           ±3 mm (0.01 ft)
           None for short  period waves; as re-
           quired  for longer period waves.
           Bulova  Accutron with hourly event
           marker.
           Continuous, once per min., or others
           optional.
           20 days minimum on self contained tide
          models  or up to one year optional.
           200 meters maximum; others available.
           Internal mercury batteries; optional
          rechargeable batteries or external
          supply.
                                          i.
          Hard Anodized Aluminum 20 cm (8 in.)
          diameter by 38 cm (15 in.) long.
PRICES:  Not available
COMMENTS:
at time of writing.
The electromagnetic current meter may find some use as a portable de-
vice for, survey work.  The rather novel wave gage is essentially a head
sensing device, and would appear promising as a secondary element for
use with head-area type primary devices for certain specialized
applications.
                                  269

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MANUFACTURER:  J-TEC ASSOCIATES, INC.
               317 7TH AVENUE
               CEDAR RAPIDS, IOWA  52401
               TELEPHONE  (319) 366-7511

PRODUCT LINE:  LIQUID FLOWMETERS, CURRENT METERS

DESCRIPTION:

J-TEC Associates Inc., a recently established firm (1968), has devel-
oped a sonic vortex flow measurement technique which they believe "will
advance the state-of-the-art in the water and wastewater fields".  The
company has patented a technique for the measurement of the vortex or
eddy shedding frequency behind an obstruction or strut in a fluid flow
stream by using an ultrasonic beam.  The company's liquid flowmeters,
similar to their VF-500 gas flowmeters, are designed to measure liquid
flow in full pipes; their Model CM-1106B current meter is suitable for
the measurement of open channel fluid flows.

In the J-TEC ultrasonic vortex-sensing device, an ultrasonic beam is
passed through the vortex path and,  in effect, counts the number formed
per second to determine velocity.  An ultrasonic signal is received
from a transducer across  the flow path and is modulated both in ampli-
tude and phase at the vortex shedding velocity.  The signal is processed
so that output pulses are a direct,  linear measure of flow velocity.

Liquid Flowmeters - The detected modulation frequency is used as the
primary output of the flowmeter.  This frequency can be counted for a
direct digital display of flow rate  or applied to a frequency converter
for a voltage or current  output.  Although this flowmeter uses the same
technique as the VF-500 series gas flowmeters, usable ranges for this
meter will be  (as stated  by J-TEC) approximately ten times lower than
listed for each gaseous model, respectively.  Flowmeters utilizing the
J-TEC technique have been used over  a  strut Reynolds number range of
100 to 36,000; in terms of  pipe  Reynolds number, a value of 900  is nec-
essary to achieve sufficiently  turbulent flow to support vortex  forma-
tion.  There are no moving  parts  associated with this device.  Liquid
flowmeters are available  only on a special order basis.

Current Meter -  The CM-1106B  is  a true fluid  speed  (current) indicator
for use  in open  channel flows.   As  in the  case of  the liquid flowmeter,
this  device  uses  the J-TEC  ultrasonic  technique for  flow speed measure-
ment.  An electronic processor  provides the  user with a choice of  out-
puts  - pulse frequency proportional  to fluid velocity or analog  voltage
 corresponding  to  fluid velocity.
                                   270

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 SPECIFICATIONS:

 Current  Meter

     Accuracy:

     Speed  Range:

     Power:

     Size:
±1%

0.1-5 m/s (0.3-15 fps) (standard)

12 VDC, 50 mA

12.7 cm (5 in.) High X 5.08 cm (2in.)
Diameter
PRICE:  Flowmeters - Available on special order basis only

        Current Meter  (CM-1106 Serires) - $1,090.00 up  (depending .
        upon model, display, and accessories used)

COMMENTS:

As long as the Strouhal number remains constant, the number of vortices
generated per unit time is directly proportional to the flow velocity
of the medium involved.  Any change in the diameter of the strut, e.g.,
due to build-up or debris entanglement, will change the sensor's cali-
bration constant and its accuracy.  Therefore, unattended operation in
wastewater flows does not appear attractive.
                                 271

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MANUFACTURER:
PRODUCT LINE:
KAHL SCIENTIFIC INSTRUMENT CORPORATION
P. 0. BOX 1166
EL CAJON, CALIFORNIA  92022
TELEPHONE:  (714) 444-2158

CURRENT METERS, ACCESSORIES, FLOATS, AND
FLUORESCENT DYES
DESCRIPTION:

"KAHLSICO" markets a wide range of hydrological and oceanographic in-
strumentation, including the products of GM Manufacturing and Instrument
Corporation discussed earlier.  A few of their offerings will be
described.

Integrating Remote Water Current Motor  (No. 231WA550) - This meter uses
a  Savonius type rotor for measurement of liquid flows.  The rotor uses
two balanced Savonius sections, one above the other and displaced
90 degrees around their circumference to assure actuation omnidirec-
tionally  about the horizontal plane of  the sensor.  The rotor has
14 magnets aligned in its base to inductively activate (14 times per
revolution) the electrical  switch in the sensor's housing.  The opening
and closing of the electrical circuits, which is directly proportional
to the speed of the water current, is monitored by a pulse-shaping
network,  the 0 to 20 mA output of which goes into a counter, fast inte-
grator, and finally  to the  indicator meter  (and, optionally, a recorder
or other  readout).   The response time of the circuit is practically
instantaneous; it readily follows any changes in the turning rate of
the sensor.  The system does not saturate and is said to be able to
discriminate and count the  actuations of the sensor, even when it is
exposed to a fast current of 3 m/s  (6 kn).

Fluorescent Dyes - Fluorescent  colors are available in either red or
yellow/green.  Unless otherwise specified,  red  color is supplied on
orders.  Yellow/green provides  a stronger color when testing silty
waters as the  grains of silt absorb  the fluorescent red.  When used in
a closed  system  such as a sewer conduit, the dye will last for several
days.   Depending upon the  clarity of the water, 2  to 5 tablets will
provide a visibility of 1 part  per million.  The tablets are 2.9 centi-
meters (3/4  inch)  in diameter and packed 100 per plastic envelope.
Maximum absorbance  is  550 my.   Dye  cubes are generally used for oceano-
graphic studies  or where large  masses have  to be traced.  Kahl also
markets an in-situ  opto-electronic  fluorometer  (VARIOSENS).

Current Drifters  and Drogues -  KAHLSICO offers  a number of current
drifters  and drogues in three basic types.  The surface drifter is
 essentially two  sealed, heavy-gauge, clear  plastic envelopes sized
 7.5 x 12.5 cm (3x5  in.).   A drift  envelope  is a similar waterproof
                                    272

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envelope measuring 15 3.23 ess,  (6x9 in.) with a 34 grams  (1.2 oz) weight
at the Bottom to provide vertical floatation.  Since only a small por-
tion of the envelope is exposed to the wind, the major drift force is
the surface water current.

The ball-shaped Tri-Planar Surface Drogue is molded from brightly-
colored, buoyant, polyethylene plastic, with a 53 cm (21 in.) long
flexible, weighted stem.  This 15 cm  (6 in.) diameter drifter has two
vertical discs, 180 degrees apart, bisected by a horizontal disc at
their center.  The flexible stem has  a tubular weight crimped at its
lower end which keeps the drogue floating just below the water surface,
to eliminate the effect of wind.  The horizontal disc prevents undue
motion in the vertical direction while the vertical discs have the
effect of presenting the same surface area to water currents from any
side.

The Surface Current Drogue has a large floatation cork at the top of
the 53 cm (21 in.) long, flexible stem and a 20 cm (8 in.) diameter
saucer at the weighted bottom end.

Also offered is the Woodhead sea-bed  drifter which has been in suc-
cessful use for over two decades for  surveying bottom currents.  The
brightly colored, 20 cm (8 in.) diameter, plastic dish has a series of
holes to facilitate vertical descent  to the sea-bed.   To assure rapid
passage through deep waters, several drifters are usually attached to
a salt block which dissolves in from  20 to 30 minutes to release the
drifters which are then jogged along the bottom by the water current.

SPECIFICATIONS:

No. 231WA550 Integrating Remote Water Current Meter
Speed Range:

Meter Scale:
Threshold and Sensitivity:

Distance Constant:


Recorder Output (Optional):
0.05 to 3 m/sec. (0.1 to 6 knots)

0 to 6 knots in 0.1 knot and 0 to
10 ft/sec in 0.2 ft/sec (m/sec scales,
as well as expanded scale ranges of
0 to 1 knot and 0 to 6 knots, are
available on special order).

0.05 m/sec; 0.1 knot, 0.17 ft/sec

0.74 revolution = 30.48 cm (1 ft) of
linear water movement.

A recorder connector provides 0 to
20 mA maximum output to operate a
250 ohm minimum internal impedance
circuit for a recorder, data logger,
etc.  (Other outputs available on
special order.)
                                  273

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Optional External Power Supply:

Built-in Power Supply:

Battery Life:
Dimensions:



Weight:


PRICES:
12 to 30 VDC, 6 mA consumption at
18 VDC, available on special order.
Four Alkaline Batteries, each 4.5V,
connected in series (18V total).
Approximately 150 hours.
   Sensor            Control Box
20x20x26 cm
(8x8x10 in.)

3 kg (6 Ibs)
21x16x14 cm
(8.3x6.5x5.5 in.)

2 kg (4 Ibs, with
batteries)
No. 231WA550 - Integrating Remote Water

   Current Meter	

COMMENTS:
                          $763.00
Items offered by Kahl were  discussed  in  Section VI and will not be
commented  on further.
                                  274

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 MANUFACTURER:
F. B. LEOPOLD COMPANY
DIVISION OF SYBRON CORPORATION
227 S. DIVISION ST.
ZELIENOPLE, PENNSYLVANIA  16063
TELEPHONE (412) 452-6300
 PRODUCT LINE:
 PRIMARY DEVICES - FLUMES,  OPEN FLOW NOZZLES
 SECONDARY DEVICES - TRANSMITTERS,  RECEIVERS

 DESCRIPTION:

 Flumes ~ Leopold-Lagco fiberglass  flumes are Palmer-Bowlus type primary
 measuring devices with a rectangular cross-section.   They are molded of
 LEO-LITE, a patented plastic resin material reinforced with glass fi-
 bers.   Installation is directly in the sewer line, normally at a stand-
 ard  straight-through manhole.   Flume construction is  claimed to be
 sturdy enough  to permit direct use as a concrete form in permanent in-
 stallations, and do not require maintenance.

 Leopold-Lagco  flumes are available in three standard  types - fixed,  in-
 sert,  and cutback.   The fixed  type is generally  used  in new construc-
 tions  where the flume is installed in place of an equivalent length  of
 straight  pipe.   The insert type is designed for  use in those installa-
 tions  where the flume can be inserted into  an existing half section  of
 sewer  pipe; it  is  particularly well suited  for flow "spot  checks"  where
 a more permanent installation  is not required.   A modification of  the
 insert model, the  cutback, is  used where  space is critical.   Inserting
 the  cutback" into a manhole or vault outlet  provides  more room upstream
 for metering, sampling,  or other devices.   Design capabilities  of  this
 flume  include the  following:

        Demonstrated measurement of low flows in near-zero range.

     *  Can be  equipped with a  pointer gage mounted on  it  for in-
        termittent  flow  readings.

     •  Can be used with all of the better-known float-actuated
        meters,  including those with  telemetering capabilities.

        Some installations have successfully incorporated air
        bubbler systems.  However,  provisions have to be made to
        eliminate the aspirating effect caused by flow past the
        bubbler orifice.

F.  B. Leopold also manufactures a complete line of LEO-LITE Parshall
flumes and Parshall flume liners in throat widths from 7.6 cm (3 in.)
to 2.4m (8 ft).  Complete LEO-LITE  Parshall flumes have stiffeners and
                                   275

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spacers for immediate field installation.  Leopold also offers cast
iron parabolic flumes (open flow nozzles) in a variety of sizes.

Float in Flume Transmitter - Leopold float-in-flume transmitters are
designed to continuously indicate the flow of sediment-laden liquids as
they pass through Lagco or Parshall flumes or parabolic open flow noz-
zles under gravity conditions.  Liquid flow is indicated by the direct
sensing of the level of the liquids within the flume or nozzle; flow
data are transmitted either electrically or pneumatically to a remotely
located flowmeter.

The transmitter is either mounted directly on the wall of the Parshall
flume or on the parabolic nozzle itself.  A corrosion-resistant "ski"
type sensor (float) rides directly on the surface of the liquid flow
stream; it does not cause disturbance on the surface of the liquid or
excessive oscillation in recording instrument.  As the surface of the
liquid rises or falls, depending upon the flow through the flume or
nozzle, the sensor changes its position accordingly.  This movement
produces proportional angular movement of the sensor arm and shaft on
which it is supported.

For electric transmissions, the shaft arm angular movement is trans-
ferred to a stylus riding over a characterized cam which is corrected
for non-linearity and furnishes a linear signal proportional to flow
which is transmitted every 15 seconds, with a pulse duration varying
from a fraction of a second to approximately 12 seconds.  Three sec-
onds of each 15-second period are required for the receiver to reset
for the reception of the next signal.

For pneumatic  operation, the  shaft  arm  angular movement  is transferred
to a shaft carrying  a cam  characterized to the head quantity  relation-
ship of the flume.   A pneumatic tracing device senses  the profile  of
this cam and transmits a linear,  3  to 15 psig pneumatic  signal through
an amplifying  relay  to the receiver.

Advantages of  this device  include the following:

      •  Reduces  installation space
      •  Faster responses  to flow changes
      •   Reduces  material costs -  eliminates  stilling  wells,  con-
        necting piping and fittings,  large float  and  cable,  back
         purge system,  etc.

 Recorders  - The Leopold  Type "K" electric receiver/integrator (total-
 izer)  is adaptable for installation at locations  remote from the trans-
 mitter and will operate over private two or three wire systems or a
 pair of leased telephone wires.  Designed to operate with an accompany-
 ing time impulse transmitter, this receiver can be applied to the meas-
 urement and control of flow, level, pressure, and temperature.  The
 unit features a 30-centimeter (12-inch), 24-hour chart and nonremovable
                                   276

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chart hub; indicator, which  operates over  standard  scale - 0 to
100 percent of chart range;  and a  continuous  reading,  seven-digit  type
totalizer.

SPECIFICATIONS:

Leopold-Lagco Flumes

Accuracy:

Flume Sizes:

Flow Capacity:

PRICES:
up to ±2%

15.2 to 183 cm (6 to 72 in.)

7.25 to 3,313 Si/s (0.25 to 118 cfs)
Leopold-Lagco flume prices range from around $300 to over $3,000 depend-
ing upon material (i.e., LEO-LITE 87 or 82) and additional features such
as integral stilling well, scale, etc.

COMMENTS:                                               .   .       •    .

These products have been discussed in Section VI andawill not be com-
mented upon here.
                                  277

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MANUFACTURER:  LEUPOLD & STEVENS, INC.
               P.O. BOX 688
               600 N.W. MEADOW DRIVE
               BEAVERTON, OREGON  97005
               TELEPHONE (503) 646-9171

PRODUCT LINE:  FLOWMETERS, RECORDERS, GAGES

DESCRIPTION:

Leupold & Stevens is an old-line company whose products probably need
little introduction.  It is to be noted that they have recently dis-
continued their Model 561R, a float-in-flow transmitter arid remote reg-
istering total flowmeter, and Model G161R, a bubbler-type remote
registering total flowmeter.  This company currently offers, in addition
to staff gages, devices for measuring flow rates and totalizing volume
in open channels for industrial wastes and municipal sewage.  These in-
clude the Stevens Model 61 series total flowmeters and the Type F
recorder.

Flowmeters - Stevens total flowmeters are designed for on-site measur-
ing of open channel flows.  They are available in either English or
metric units, and-can be used with any type and size of weir or flume.
With appropriate cam, gears, and scale, flows up to approximately
800,000,000 liters  (several hundred million gallons) per day can be
measured through large sizes of Parshall and other types of flumes.
Conversely, a full scale range as small as 0-53,200 Upd (0-14,000 gpd)
through a 22-1/2-degree V-notch weir is available.  An AC synchronous
motor drive powers a 7-digit totalizer (for indicating volume) and
chart drive.  For applications where commercial power is not available,
an 8-day, spring-drive clock can be obtained.  Figure A shows a typical
manhole flow measuring installation.

The Model 61M provides visual indication only.  The indicator plate is
graduated to show instantaneous flow rate as noted by the indicator
pointer.  A red clip on the indicator plate is positioned by the pointer
to indicate peak flow.

The Model 61R uses a strip chart to provide a permanent record of flow.
A standard 15m by 10.1 cm  (50 ft by 4 in.) strip chart is printed on
humidity-resistant  tracing paper.  Curvilinear time graduations compen-
sate for arc swing  of  the marking pen, with six minor divisions between
major divisions.  Charts are time overprinted every 2, 3, 6 or 12 hours,
depending upon time scale.  The chart has uniform divisions for flow,
consisting of 7 major  and 5 minor divisions.

Available time scales  are 8.5, 12.7,  25.4, or 50.8 cm  (3-1/3, 5, 10 or
20 in.) of chart  travel per day  giving 180, 120, 60, or 30 days of con-
tinuous records,  respectively.

Up to 180 days of unattended  operation is claimed for  these devices.
                                   278

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Figure A
       279

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It is recommended by the manufacturer that a stilling well  installation
and standard cylindrical float be used whenever possible  in order  to
obtain better accuracy and chart record  (a properly designed stilling
well dampens out surface undulations and wave action).  For some appli-
cations, however, a scow float installation can be used to  good advan-
tage.  Figure B shows two such installations.
                Stilling Well
                Installation
Scow Float
Installation
                                Figure B
 Recorder  -  It  has been claimed that the Stevens Type F recorder is the
 lowest  price instrument of its kind for recording open-channel flows
 through Parshall flumes or 90-degree V-notch weirs.   In operation, a
 horizontally supported chart drum is turned by a float (resting on the
 water being measured)  proportional to changes in water level.  A pulley
 drive mechanism, controlled by an 8-day clock, moves the pen across the
 chart at  a  constant speed.  The combined movement of the drum and pen
 produces  a  graphic record of changing water levels.

 SPECIFICATIONS:

 Operating features and characteristics are discussed in the preceding
 equipment descriptions.

 PRICE:

 Standard  prices were not available at the time of this writing.
                                   280

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COMMENTS:

Leupold & Stevens equipment has proven to be rugged and reliable in
many types of wastewater measurements.  They have also provided custom
application telemetering equipment ("telemark") for more complex sys-
tems use.
                                281

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MANUFACTURER:  MANNING ENVIRONMENTAL CORP.
               120 DU BOIS STREET
               P.O. BOX 1356
               SANTA CRUZ, CALIFORNIA  95061
               TELEPHONE (408) 427-0230

PRODUCT LINE:  LIQUID LEVEL MONITOR

DESCRIPTION:

The Manning F-3000 Dipper flowmeter series technique is basically a
method of detecting liquid level in open channel flow by sensing the
surface of the water.  The control electronics are included in a
modular package, which is mounted, for example, on a portable bracket
at the top of a manhole.  A thin, non-corrosive probe is lowered on a
wire controlled by a small precision motor.  When the metal probe
makes contact with the liquid surface, a microampere circuit is made
through the conductive liquid to a ground return.  This signal reverses
the motor, raising the probe slightly above the surface.  After 5
seconds, the probe is lowered to the surface again, and again retracts.
This "dipping" action continues with the probe just above the surface of
the liquid.  These changes in cable length are translated to a rotation
of a measuring wheel.  See the electromechanical schematic in Figure A.

The flowmeter converts the height signal into a flow rate recording,
a total flow recording, and sampler switch to provide flow proportional
sampling.  It can convert from height to flow measurement for many types
of pipes, flumes, and weirs.  The rotation of the height measuring wheel
controls an electronic servo system to change to an output which is
proportional to flow.  A channel selector allows easy selection of proper
channel shapes — round pipes, weirs, flumes.  The flow proportional
output  (1) positions a pen indicating instantaneous flow rate on a
recording chart or  (2) provides an indicator showing instantaneous flow
rate and  (3) rotates a potentiometer which provides an input to the
totalizing circuit.  This circuit generates a pulse stream proportional
to the flow and the accumulated count is shown on a total flow counter
on the front panel.

Advantages claimed for the Manning portable flowmeter include:

      •  Quick installation at street level — The Dipper Flowmeter
        allows one man to install this meter at street level in less
        than 10 minutes.

        Sensor not affected by floating debris — No floats, scows,
        tubes, capacitive plates for debris to hang on.  No stilling
        wells to clog.  The Dipper sensor never enters the flow.
                                   282

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    •  Direct reading accuracy — Direct mechanical coupling to the
       surface level gives better than  .003m  (0.01 ft) level accuracy
       over the total range.  Servo-controlled,  electronic conversion
       provides extremely high accuracy for flow rate and total flow.

     •  Easy-to-read flow chart — Switch selectable  (7 day or  24 hour)
       circular chart gives  easy to read indication of changes in
       flow rate  with time,  peak flow,  etc.   Operates with a spring
       driven, 8-day clock drive.

     •  Digital Total Flow  Counter ~ A non-volatile  counter records
        total  flow over  the given time period.  Records with digital
       accuracy.

     •  Battery Operation — Operates on small 12-volt rechargeable
       battery.

SPECIFICATIONS:

     Maximum Height of Flow Range:

        6-24 in.   (F-3024)
       12-48 in.   (F-3048)
       15-60 cm (F-3060)
       30-120 cm  (F-3120)

     Channel Shapes Included  (Switch Selectable):

       Round pipe
       V-Notch Weir
       Palmer-Bowlus Flume
       Parshall Flume
       Leopold Lagco Flume
       Cipolletti Weirs
        (Others available on special request).

     Maximum  Total Flow Recording:
       Up to  999,999 times maximum flow per minute in channel.
        (For  example:  If maximum flow is  1000 gallons per minute —
       maximum recording 999,999,000 gallons.)

      Size:  23x36x20  cm (9x14x7.75  in.)

      Weight:   5.5 kg (12 Ibs)

      Flow Rate Indication:  0 to 100% in 5% divisions
                                    284

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PRICE:  Approximately $1,000 and up, depending upon options.

COMMENTS:                                      -.-'..

This portable liquid level monitor and flow converter has a lot to
recommend it as a secondary device for translating depth into flow rate
in many storms or combined sewer applications.  The range is less than
might be desired for some sites, and collision with surface debris could
cause an oscillation of the pendulum-like dipper probe resulting in some
inaccuracy until the swinging motion subsides.  It also might be pos-
sible for the probe to become coated after extended periods of use,
which could result in a zero-offset.  Otherwise, the unit appears quite
promising and merits serious attention as a new technique for measuring
liquid levels.
                                  285

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MANUFACTURER:  MARTIG BUB-L-AIR
               2116 LAKEMOOR DRIVE
               OLYMPIA, WASHINGTON  98502
               TELEPHONE (206) 943-2390

PRODUCT LINE:  PORTABLE LIQUID LEVEL RECORDER

DESCRIPTION:

This unit is a very recently introduced (Spring 1974) device for meas-
uring and recording depths of wastewater flows.  It is expressly de-
signed for manhole use.  The equipment package for an installation
consists of a recorder; compressed air bottle; regulators, connecting
hose, and fittings; sensing probes for sewer pipe; and miscellaneous
slings and straps for mounting in a manhole.  The device measures flow
depth only, and the user must apply conversion factors as appropriate
for the primary device employed.

SPECIFICATIONS:

The spring-wound recorder has two settings for either 24 hour or 7 day
operation and uses 20.3 cm  (8 in.) diameter charts graduated from 0 to
30 inches.  The pen has a fine tip for use in humid environments and
uses three drops of ink for a fill.  One and two pen models are avail-
able and are housed in a weatherproof case.

The compressed air bottle is lightweight aluminum with a 1,260,000 kgf/
sq m  (1,800 psi) working pressure.  Various sizes are offered for fill
lifes from 3 to 8 weeks.  The primary regulator is a single stage unit
which reduces bottle pressure to about 24,600 kgf/sq m  (35 psi).  The
secondary regulator is used to adjust air flow rates to bubbles per sec-
ond as visually observed through a mineral oil reservoir.  Stainless
steel sensing probes are available in standard sizes from 15.2 to
76.2 cm  (6 to  30 in.), and  other sizes can be supplied on special order.

PRICES:

Complete packages  start at  $1,149.  These packages include a one-pen
recorder, three sensing probes, and all  equipment necessary for instal-
lation and use.

COMMENTS:

These devices  are  sold direct from the  factory only, on a thirty-day,
free-trial basis.   The manufacturer  is  pleased that  in  the nine months
that  this offer has been in effect, not  one unit has been returned, and
ninety percent of  their  customers  have  placed orders for additional
equipment.
                                   286

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 MANUFACTURER:  MARY TEC, INC,
                C/0 HARRY H. BARNES
                613 EAST BAYVTEW,  HILLSMERE   '
                ANNAPOLIS, MARYLAND  21403
                TELEPHONE (301)  261-2987

 PRODUCT LINE:  ACOUSTIC LIQUID  LEVEL MEASURING  SYSTEM '

 DESCRIPTION:

 The Aquarius  Model 2001 or 2002 Liquid  Level Measuring
 System is  a very recenlty developed (patent pending)
 instrumentation system which employs acoustic ranging
 techniques to measure liquid levels to  within 0.03  cm
 (0.001 ft) over a range of 0 to 30m (0  to 100 ft).  Con-
 tinuous calibration is employed to automatically  com-
 pensate for ambient changes of  temperature, humidity,
 and pressure  of the gaseous medium above  the liquid.
 This technique  entails monitoring  a coincident  return
 signal from a known distance within the sensor  head as-
 sembly,  mathematical circuitry  manipulation, 'and  appli-
 cation of  the resultant factor  to  the signal of interest
 for Determination of the unknown distance.

 Advantages of this  system are that it has no moving parts,
 does not contact  the liquid being  monitored, and  report-
 edly can be used  in extreme environmental conditions to
 monitor corrosive liquids  in corrosive  atmospheres.

 A complete system,  shown in Figure A consists of  (a) sensor
 head assembly,  (b)  stilling well,  and (c) remote  electronic
 package and control  panel  for one  or more sensor head
 assemblies.

 The  function  of the  stilling well  is  to support the sensor
 head assembly and contain  the transmitted and return
 acoustic signals.  It  consists of plain pipe of appropriate
material,  the type of material used being dependent upon
 the  liquid being monitored.

 The Model 2001 and Model 2002 are similar in outward ap-
pearance, except that the Model 2001 is continuously
 energized whereas the Model 2002 can be interrogated at
specific intervals and will respond within 50 milliseconds,
no power being consumed during the quiescent period.
K-
                                                              Figure A
                                 287

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SPECIFICATIONS:

Accuracy*:




Power:


Output:
0.3 cm throughout 30.3m range
(0.01 ft throughout 100 ft range)

0.03 cm throughout 3.03m range
(0.001 ft throughout 10 ft range)

Model 2001, 1 amp @ 5 VDC
Model 2002, 3 amps @ 5 VDC (only during
            interrogation period)

16 line, 4 bits per digit, 4 decimal
BCD  (Other outputs optional - e.g.,
binary, ASCII, or analog)
PRICE:  $1,400 and up depending upon output desired  (e.g., sample .
        depth, totalized flow, etc.), materials of construction, etc.

COMMENTS:

The Aquarius  is  a secondary  device  that  shows great  promise for meas-
uring  liquid  levels  in  storm or combined sewer flows.  The stilling
well pipe can act as a  damper to  surges  in liquid level by using a
small  hole to restrict  flow  to it.  This could present plugging
problems,  and a  configuration with  many  small holes, e.g., about
0.3 cm (1/8 in.) in  diameter, will  be preferred.  In addition, the
stilling  well acts as a sort of acoustic waveguide,  eliminating the
echo problems that have plagued attempts to use many other types of
acoustic  level sensors  in  manholes, meter vaults, etc.

The unit  must be considered  still in the prototype  stage.  Only one
has been  delivered  (to  the U.S. Geological  Survey)  at the time of this
writing.   Advanced  integrated circuit  technology  (CMOS) has been in-
 corporated in the electronics design,  and power requirements  are low.
 Based on preliminary tests,  battery life on Model 2002 should exceed
 one year.  The device is all digital and so is  immediately computer
 compatible.
 *  Greater accuracies are optional*
                                    288

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 MANUFACTURER:   MEAD INSTRUMENTS CORPORATION
                ONE DEY LANE
                RIVERDALE,  NEW JERSEY  07457
                TELEPHONE (201) 835-5988

 PRODUCT LINE:   OPEN STREAM VELOCITY PROBE (TURBINE)

 DESCRIPTION:
   •*

 The  Model HP-301 Open Stream Velocity  Probe was  designed  for use in
 pollution control applications requiring  the  measurement  of open stream
 water velocities*.   Readings are reported to  be  instantaneous  and ac-
 curate with no  counters, timers,  or lengthy test periods  required.  All
 readings are direct and may be made by untrained personnel.  The adjust-
 able head of the probe allows its insertion into pipe  ends and vertical
 velocity measurements.   The unit  consists of  a hand held  probe
 (Model PT-301)  and  a portable indicator (FI012P).

 The  PT-301 Probe consists  of a low inertia Delrin turbine mounted in a
 protective shroud at the end of an aluminum handle.  The  turbine, when
 immersed in a flowing stream,  rotates  at  a speed in direct linear
 relationship to the fluid  velocity.  A small  magnet sealed within the
 turbine hub produces an electrical pulse  in an adjacent induction trans-
 ducer for each  rotation.   The frequency of these pulses is thus  also a
 direct measure  of the fluid velocity.   The FI-12P indicator is actually
 a  portable frequency meter or frequency-to-DC converter.  It amplifies
 and  conditions  the  pulses  to drive a meter indicator in a direct  rela-^
 tionship  to their frequency.   The indicator scale is calibrated  to read
 in the desired  units of  fluid velocity.   The  electronic system is stable,
 accurate,  and all solid state.  It  is  drift-free and requires no  opera-
 tional adjustments.  All power  is  obtained from  a set of eight standard
 •C"  size  flashlight batteries.  The  current drain is less than that of
 a  normal  flashlight bulb.

 SPECIFICATIONS:

Various single  or dual ranges are available up to 4.57 m/s (15 fps)
water velocity, with 3 m/s  (10  fps) being  standard.   The threshold of
operation  is approximately 0.08 m/s  (0.25  fps) for all ranges.
Indicator:

Probe:
250°, 5.6 inch long scale; weight
2.04 kg (4.5 Ibs)
Adjustable handle; weight 0.76 kg
(20 oz)
   Includes measurement of industrial or municipal pollution entering
   streams or rivers and flow out of large pipes or ducts.
                                  289

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PRICES:

HP-301-A
OPEN STREAM "VELOCITY PROBE, portable,
battery operated.  Complete with indicator,
probe, and case.  Ready to use.  Single
HP-301-A2  As above except dual range	

COMMENTS:
                                          ---$420.00
                                  	$445.00
The lack of any recording provisions will be a handicap in all but
brief survey work.  The unit is designed for attended operation, so
fouling should not present too great a problem except in the dirtiest
flows.
                                   290

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 MANUFACTURER:
 PRODUCT LINE:
 DESCRIPTION:
MERIAM INSTRUMENT
DIVISION OF THE SCOTT & FETZER COMPANY
10920 MADISON AVENUE
CLEVELAND, OHIO  44102
TELEPHONE (216) 281-1100

ORIFICE PLATES AND METER TUBES: PITOT TUBES: LAMINAR
FLOW ELEMENTS: DIFFERENTIAL PRESSURE READOUT AND
RECORDING INSTRUMENTS
 Meriam manufactures  three differential-pressure type primary elements.
 Their standard orifice plates  are 0.3 cm (1/8 in.)  thick 304 stainless
 steel, but  can also  be fabricated from monel brass  or other materials
 on special  order.  Raised-face orifice flanges are  offered for  line
 sizes from  1.3 to  58 cm (0.5 to 24 in.);  standard orifice meter tubes
 range from  2.5 to  30.5 cm (1 to 12 in.).   Other sizes may be available
 on special  order.  Meriam also manufactures  simple  impact tubes of
 stainless steel in lengths from 25.4  to  101.6 cm (10 to  40 in.) and
 produces a  wide variety of laminar flow  elements, which  are differential
 pressure producers operating on capillary flow principles and are nor-
mally used  to  measure  gas  volume rates of flow.  None of the foregoing
 is  deemed suitable for measuring typical  storm or combined sewer flows,
and they will  not be discussed further.

Meriam manufactures  a  very wide  line of U-type, well-type,  and  inverted
manometers  together with a complete range of  scales  for many  applica-
Iw£nc* -°f  85*ater ^terest in the wastewater field  is their bellows
D/P Series  1100 line of differential pressure indicators which  are
schematically  illustrated  in Figure A.  Operation of  the Meriam
                     -LOW PRESSURE CONN.
                             Figure A
                                 291

-------
Hydraulically Connected Differential Pressure Unit is based on the
interaction of two opposed bellows attached to a machined center plate.
All space enclosed by the two bellows is completely evacuated and fluid
filled   The low pressure bellows shaft is connected by a linkage to
transmit bellows motion to the output shaft.  Pressures from the
actuating source are introduced to both sides of the bellows system
through either set of taps in the high and low pressure housings.  When
pressures on both high and low pressure bellows are equalized, the unit
remains at zero.  As differential pressure increases, the high pressure
bellows contracts, forcing fill fluid through the pulsation dampener
passage around the overrange valves into the low pressure bellows.
This  causes the low pressure bellows to expand and the attached shaft
to move outward.  Through linkage, the linear motion of the bellows
shaft is  translated into angular rotation of the output shaft.  _Move-
ment  of fluid from high pressure into low pressure bellows continues
until the force created by the  differential is equalled by the  tension
on  the range  springs.  This unit is designed for sustained measurement
and fast  response speed.  Overrange protection helps assure long  periods
of  trouble free service.  Temperature compensation assures accuracy
under various adverse operating conditions.  The bellows are  fabricated
of  stainless  steel,  steel, monel,  aluminum and others.  They  require no
 lubrication for  life and include an externally adjustable pulsation
 damper.

 Meriam Series 1300  recording flow meters are designed to work with the
 D/P bellows units.   Spring-wound or electric chart drives  in a variety
 of chart rotations are available.   Also available are integrators, as
 well as pressure and temperature pens.
                                    292

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MANUFACTURER:  METRITAPE,. INC.
               77  COMMONWEALTH AVENUE
               WEST  CONCORD, MASSACHUSETTS   01742
               TELEPHONE  (617) 369-7500

PRODUCT LINE:  LIQUID LEVEL MONITORS AND ACCESSORIES

DESCRIPTION:

The  unique  and patented METRITAPE  level  sensor,  schematically depicted
in Figure A, consists of  precision-wound linear, resistive helix held
away from high-strength conducting base  strip by thin and stable insu-
lation  layer along edges  and back.   A composite  outer jacket encloses
and  protects the inner winding system, and acts  as a diaphragm to
receive the pressure  of surrounding  material.  Positive or negative
pressures are balanced by pressure-equalizing breather mounted at sensor
top.  The resultant continuous METRITAPE sensor  is suspended from above
throughout the full liquid height  (see Figure B).  As the liquid rises,
the  length of unshorted resistance helix, extending from the top to
the  liquid surface, decreases.  The  resulting uniform resistance change
with level change may  be  read, locally or  transmitted thousands of feet
over a  simple leadwire pair, for remote  level indication, alarms, and
controls.

METRITAPE claims a number of advantages for its gaging systems
including:                                                     '

      •   The sensor produces highly accurate readings of material
         levels,  generally to better than ±0.1% (in liquids)  and
         independent of depth;  long term stability of output  is  that
         of a precision wirewound resistor.

      •   The transducer essentially has  no moving parts,  generates
         its electrical signal  directly  at the point  of measurement
         (the air/liquid interface),  and eliminates the need  for
         moving floats, pulleys,  guy wires,  linkages,  compressors,
         air dryers,  mercury columns, etc.

      •   Level measurements are substantially independent of material
         specific gravity, product  or air temperature, and gas
         pressure or  vacuum above the material  surface.

      •   Sensors can  transmit their electrical outputs directly,
         without preamplifiers or electromechanical converters,
         for distances of  several thousands of feet, at low impedance
         level and  via low-cost signal-wire pairs, without signifi-
         cant accuracy loss.
                                293

-------
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                  294

-------
      •  The sensor electrical output is suited for real-time computer
         monitoring and automatic control.

      •  Metritape systems can provide local analog level readout at
         the top, as well as analog or digital display at one or
         several remote locations.

      •  For highly critical automation systems, two sensors (having
         small cross-sectional area) can be mounted back-to-back to
         provide continuous and automatic self-checking.

      •  Frequency response of the sensor is sufficiently fast to
         allow oceanographic wave motions to be accurately measured
         and recorded.

 A METRITAPE level system (see Figure C)  generally consists of the fol-
 lowing parts:   (1)  Metritape sensor and capillary breather assembly;
 (2)  Electrical signal-conditioning and alarm circuitry,  usually in
 NEMA-style panel box;  and (3)  Level readout display (analog and/or
 digital),  plus adjustable level alarms with indicator lights and an-
 nunciator  flasher and  horn.   For remote  signal transmission, signal
 conditioning circuits  are used to drive  encoding  and telemetry  equip-
 ment,  or may drive  an  analog strip-chart recorder or digital printer
 for  permanent  recording.

 The  styles  of  Metritape  liquid-level sensors  most commonly used in
 water, wastewater,  and sewage  applications  are described below.   These
 include  general-purpose,  corrosion-resistant,  and ruggedized sensor
 constructions,  and  two basic sensor resolutions,  general-purpose  and
 moderate precision.  The  company expects  in the near future to  introduce
 precision liquid sensor Types  PLS and  PLS/S,  having  increased resolution
 for  average  deviations in the  0.003-0.006m  (0.01-0.02 ft)  range.

 Type LS  General-Purpose - Useful in water,  petroleum, municipal sewage,
 and  industrial wastewater not  having high concentrations of  chemical
 solvents or  corrosives.   The outer wetted jacket  is  adhered Mylar
 polyester, and  the sensor is protected on three sides by an extruded
 bumper-strip of  chlorinated vinyl (CPVC).  Nominal sensor outer dimen-
 sions are 3.6 x  0.3 cm (1.4x0.25 in.), with OD of the upper cap being
 3.8  cm (1.5  in.).  Resistance helix has nominal 1.3  cm (0.5 in.) winding
 pitch, 30 ohms per foot,  and temperature coefficient of 0.0001 ohm/
 ohm/°C.  Available in  lengths from -1.2 to 305m  (4 to 100 ft), sensor
 average deviation is ±0.1 ft) or better, substantially independent of
 sensor length.  The stabilized Type LS/S provides accuracy upgrading.
 The  type LS sensor is designed for an outdoor ambient temperature range
of approximately -30° to +60°C (-20° to +140°F), unheated product, 0 to
 ±10 psi maximum pressure of vacuum.  The sensor is supplied with capil-
lary breather assembly and cast aluminum mounting box 15x15x10 cm
                                  295

-------
                        LOCAL
                        RECORDER
                        OR
                        INDICATOR
                                                   TO
                                                   REMOTE
                                                   DATA
                                                   SYSTEM
METRIP1PE
   LIQUID
   LEVEL
   SENSOR

   5-100 FT
 CONT1NOUS
   GAUGING
   RANGE
w if $
t  •* ;:/•)
               M ,:;
                -,!i
                                  TM
                           SIGCON
                           SIGNAL CONDITIONER
                           (0-1 VDC, 4-20 MA,...OUTPUT)
                     SEWER, POND STREAM, WELL OR OCEAN
                     LIQUID-LEVEL GAUGING SYSTEM
                     WITH CLAMPED OR MOUNTED
                     METRIPIPE™ SENSING ELEMENT
                        Figure C
                            296

-------
 (6x6x4 in.)-  The  type LS  sensor can also be provided with flurocarbon
 outer jacket surface for non-stick release finish,  designated Type LS(F);
 and for fast-response dynamic wave gaging, as Type LS-FR.

 Type LS-CR Corrosion-Resistant - Has heat-sealed outer jacket to resist
 highly corrosive liquids and chemical solvents.   Wetted jacket material
 is generally flurocarbon, but can be polypropylene;  and protective CPVC
 channel holder is  used whenever  this material is compatible with mate-
 rials to be gaged.  Electric winding system is as defined above,
 resulting in comparable accuracy.  Available in  lengths from 1.2 to
 152m (4 to 50 ft), and supplied  with capillary breather assembly and
 stainless-steel or fiberglass mounting box.

 .Type MPLS Moderate Precision - For increased resolution and repeat-
 abxlity,  the MPLS sensor has nominal 0.6  cm (0.25 in)  winding pitch;
 low-temperature-coefficient helix material (0.00003  ohm/ohm/°C);
 30 ohms per foot nominal helix resistance;  compliant jacketing system,
 wxth outer wetted jacket adhered  thermoplastic.   Other characteristics
 essentially as in Type LS above.

 Type LSR Ruggedized - For demanding  liquid and slurry  applications,  in-
 cluding high head pressures, high-velocity impacting,  turbulent  slurries,
 and stream containing potentially damaging foreign matter.  The  sensor
 utilxzes  toughened and ruggedized outer jacket surface, and may  require
 a  perforated or  slotted pipe mounting for  effective  stilling  action,
 without interrupting the flow to the sensor face.  This is  included  in
 "METRIPIPE" systems.

 The SigCon 700 series  signal-converter instruments convert  the
 2-terminal resistance  output of  Metritape or Metritemp sensor to any one
 of  a number of standard voltage  or current forms, such as 0-1 VDC,
     VDC, 4-20 mA,  etc.  These instruments are normally line-powered, but
 can be battery-powered for  special remote operation.   Output of the sis-
 nal converter can be used to drive analog or digital indicating meters,
 strip-chart recorders, pulse-code transmitters, or central readout and
 alarm consoles.

 SPECIFICATIONS:
 Metritape
Sensor Type

Standard LS

Stabilized LS/S

Standard MPLS

Stabilized MPLS/S
                Norn. Pitch
                (turns/foot)

                   24

                   24

                   43

                   48
Active
Lengths
10-110 ft
5-15 ft
5-110 ft
3-15 ft
Norn. AD*
(feet)
0.4-0.6**
0.3
0.3-0.5**
0.25
Avg. Devi a.
(feet).
±0.1
±0.06
±0.05
±0.03
Repeatability
(feet)
±0.05
±0.03
±0.025
±0.015
**  AD is governed by sensor length; increased to accommodate max. static head of longer sensors,
                                   297

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PRICES:

Prices vary depending upon system specifications.  As an example, a
MP/MPLS-10 "METRIPIPE" with a 3m (10 ft) operating range, a Signal
Converter 701A signal converter, and dry-writing strip-chart recorder
costs around $1,200.

COMMENTS:

The Metritape system may well find application in large, open-channel
flow measurements as a secondary device in conjunction with suitable
head-area primary devices.  Its rather high activation depth precludes
its use in smaller  flows.  It has apparently worked well in a number
of combined sewer installations.
                                   298

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 MANUFACTURER:   MOORE PRODUCTS.COMPANY
                SPRING HOUSE,  PENNSYLVANIA  19477
               .TELEPHONE (215)  646-7400

 PRODUCT LINE:   FLUIDIC FLOWMETER AND ACCESSORIES

 DESCRIPTION:

 Flowmeter - The SSPH fluidic  flowmeter is a unique flowmeter consisting
 of a meter body, sensor,  and  a  Q/I  converter.   The meter body is  a
 fluidic oscillator whose frequency  is linear-with volume flow rate
 The oscillations are detected by a  flush-mounted sensor  and  are ampli-
 fied and conditioned by the electronics  to provide a digital pulse out-
 put for totalizing and an analog output  linear  with flow rate  The
 geometric shape of the meter  body is  such that,  when flow is initiated,
 the flowing stream attaches itself  to one of the side walls  by means of
 the Coanda effect.   A small portion of the flow is  diverted  through a
 feedback passage to  a control port  (Figure A).   This feedback flow,
 acting  on the main flow,  diverts  the main flow  to  the opposite side wall
where the same feedback action  is repeated (Figure  B).   The  result  is a -
 continuous self-induced oscillation of the flow between  the  sidewalls
of the meter body.  The frequency of  this  oscillation is linearly
related  to the fluid velocity and, hence,  volume flow rate.
       side wall
 control port
                       , feedback passage
          Figure A
                                                      Figure B
                                  299

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As the main flow oscillates between the sidewalls,  the velocity of the
flow in the feedback passages cycles between zero and maximum.   The
feedback passages thereby provide a region with a substantial f1owrate
change in which to sense the frequency of the oscillating fluid in the
meter body.  This substantial variation in feedback flow xs easily and
reliably detected and results in a relatively noise-free sensor signal
which is very strong (several hundred millivolts before amplification).
The ruggedized, totally metal enclosed sensor (thermister) is further
proteSS by being located in this region which is out of the main flow
path.  The flow and no-flow conditions at the sensor tip create cor-
responding high and low heat transfer conditions between the thermistor
and ?he fluid which, in turn, cause the self-heated thermistor to tend
to vary its resistance.

COMMENTS:

This  interesting  device is  rather  new on  the market place and  is  avail-
able  only in  small  sizes, up to 10 cm (4  in.),  as yet.   Its  good  ac-
curacy30:1  rangeability,  low  pressure loss, and other  advantages make
it attractiveTor measuring pressurized flows in pipes  No  information
 is available  on coating  effects of sewage on the thermal sensor,  but
 they  could be minimal.   Clogging or plugging of the  feedback passages
 could be a severe problem and,  for this reason, no further descrxption
will  be given.
                                    300

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 MANUFACTURER:  HUESCO,  INC.
               WESTERN  DIVISION
               674 N. BATAVIA STREET
               ORANGE,  CALIFORNIA  92668
               TELEPHONE  (714)  997-5860

 PRODUCT LINE:  PROPELLER METERS AND ACCESSORIES

 DESCRIPTION:

 Muesco offers a complete line of magnetic drive propeller meters under
 the  "Rate A Flow" trade name.   Included are Model TTM main line threaded
 tube meters, Model FHM  fire hydrant meters, Model FTM flanged tube
 meters, Models GIFT and FST main line meters, Model SSC saddle meters,
 and  Model ISM insertion meters.  All of the foregoing were designed for
 use  with water (or relatively clean liquids) and do not appear suitable
 for  measuring wastewater flows.

 Model OFM is an open flow propeller meter designed for open channel or
 submerged pipe outlet use.  Available in 25.4 to 91.4 cm (10 to 36 in.)
 sizes, it features a three-bladed, non-fouling propeller molded from
 polyethelene plastic, a magnetic coupling, and bronze gear box.  The
 meter transmission is completely sealed and permanently lubricated.
 Accuracy may be within  ±2% if meter is used properly.

 Model RC100 is an instrument  that combines all features of a 30.5 cm
 (12  in.) diameter recording chart, full size indicator scale, and
 totalizer.  A hermetically-sealed switch in the meter register-
 transmitter completes a pulse rate proportional to the rate of flow
 through the meter.  This signal can be transmitted, for example, over
 leased telephone pairs, and is suitable for multiplexing.  Chart drive
 is either 24 hour or 7 day rotation.

 SPECIFICATIONS:
Model RC100

   Accuracy:

   Range:
   Power:
   Output:

PRICES:  Model OFM

         Model RC-100
±1% of full scale

24 to 1

11 VAC ±10%, 60 Hz

Optional 4 to 20 mA through 150 ohms

$340 - $425

$925
                                  301

-------
COMMENTS:

The open flow meter may find some application as a current meter for
measuring storm or combined sewer flows.  It does not appear suitable
for unattended operation over appreciable periods of time.
                                  302

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MANUFACTURER:
NB PRODUCTS, INC.
35 BEULAH ROAD
NEW BRITAIN, PENNSYLVANIA
TELEPHONE (215) 345-1879
                                          18901
PRODUCT LINE:  PORTABLE MANHOLE FLOWMETERS; V-NOTCH WEIRS; ROD GAGES'

DESCRIPTION:

NB offers a line of portable float-in-flow flowmeters, portable V-notch
weirs, and a^rod meter  (termed the FLO-ROD) for manual measurements of
volumetric flow.  Figure A shows a typical meter (Model H) installed
in a manhole.
                             Figure A
                                 303

-------
flowmeters

Series F Manhole Meter - This  portable device consists of two basic
parts - a transducer  (Figure B),  equipped with a telescoping support
and ball float, and an instrument case containing a control box and
strip chart recorder.  A sensing  unit inside the transducer determines
changes in the water  level in  the channel by measuring the angle of
Inclination of the float arm (the ball float contacts the water in the
channel).  This information is then transmitted over an electrical cable
to the recorder in the instrument case.  Here, a continuous record of
the elevation of flow passing  through the manhole is made on pressure-
sensitive chart paper.  The recording, which runs at a uniform rate for
up to 30 days, is unaffected by changes in temperatire, grease, etc.
Longitudinal lines on the  tape are used to show elevation of flow in
percentage of pipe size, and cross lines indicate elapsed time in
15-minute intervals.  In order to translate the tape recordings into
                                                               —---Trim"
          Telescoping support
                                                           .   L" ihapecl «tid« fit?J
                                                           1  against top of ontwring.
                                                                         1
                                                                         •4
                                                                       ?p^™^
                                                                      • VI
                                 Electrical cable to
                                  ihsturment box
    THE TRANSDUCER
                              Figure B
 gallons per 24 hours passing through  the manhole,  it is necessary to
 first determine the slope of the pipe.   Available  with each meter is
 a set of tables that can be used to convert elevation into rate of
 flow.
                                   304

-------
These meters are normally available for use in pipe sizes ranging from
20.3 to 111.9  cm  (8  to 48 in).  Since adjustment to various pipe sizes
is accomplished by different length float arms, one.basic unit can be
used.  Arms for pipes up to 1.8m  (6 ft) are also available.  The unit
can be installed by  one person in about 15 minutes.i A Series G meter
is offered at  the same price and  is virtually identical to the Series F
except that the ball float is replaced by the scow float used in the
Series H meter.

The power pack consists of four 7-1/2 volt rechargeable batteries that
will power the meter for approximately 9 days on a single charge.
Weekly charging is recommended, and a spare set. of, batteries and a
charger are included with each meter.

Series-H Manhole Meter - This device uses a float-in-flow transducer
similar to the Series-G flowmeter.  One of the chief differences is
that this model is programmed to  account for the well-known variation
in "n" (the Manning  roughness coefficient) with flow depth in a circular
pipe.  This is especially important for low flows (under 25% of pipe
diameter) and  can result in accuracy improvements on the order of
20-30%.  A solid state totalizer with L.E.D. display features no moving
parts.  The total maximum flow rate for the pipe at the site of interest
is determined  from NB tables and  entered via a digital thumbwheel switch
at the time of installation.  All electronics are contained in a stain-
less steel submersion proof case.  Two gel-cell batteries and a charger
are also included with each unit.  Battery life is 9 days on a single
charge.  A strip chart recorder is also provided as in the Series-G
meters.  S^iap-in function boards adopt the Series-H meters for use with
a variety of weirs and flumes as well as circular pipes.

Weirs

NB produces portable V-notch weirs in several sizes specifically designed
to measure the amount of actual infiltration in newly constructed sewers
and for measuring small discharges.  Figure C shows a typical weir in-
stallation in a pipe.

V-notch weirs produced by NB are so designed that they can be installed
by one person without the use of any tools in any pipe (vitrified,
asbestos cement, concrete,  or cast iron).   Installation can be made in
less than one minute.  The V-notch weirs are cast from weather resistant
aluminum alloy.  The dial face is cut from transparent plastic and is
calibrated for direct reading in gallons per 24 hours.  Individual weirs
are offered for six pipe sizes up to 38 cm (15 in).   For larger standard
sizes to 106 cm (42 in),  adaptors can be purchased to be used in con-
junction with the 38 cm weir (see Figure C).
                                   305

-------
        -	i'i	^	^	«	-	"	1	1	
  =;	%•:,	«•	a	as	as
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	-	:::: •••.	 •	:::	:::: •	- 	.-,••
                            Figure C
Rod Meter
The FLO-ROD is a four-sided measuring device of 2.5 cm (1 in) square
aluminum tubing calibrated on each side with a series of multipliers
for approximate flow determination.   Inserted into the center of the
flow channel, a reading  is taken at the water's surface.  The volume
of flow is then calculated from a special set of tables provided.
Three FLO-RODs cover twelve pipe sizes, from 20.2 to 121.9 cm (8 to
48 in).  Applications  include:  periodic checks of flows in sewers under
construction; quick checks for leaks and other troubles; and infiltration-
inflow studies.

SPECIFICATIONS:

Series-H Manhole Meter
Level Accuracy:
Total Flow Recording:
±0.0015m (±0.005 ft.)

999.999 units maximum
                                    306

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 Flow Rate Indicator:
 Flow Rate Recorder
 Size-Electronics Case:
 Total Shipping Weight:
 PRICES:
0-100% in 5% increments
0-100% in 2% increments
30.5x30.5x22.9 cm (12x12x9 in)
30.8 kg (68 Ibs)
Series-F & G Meters 	 -
Series-H Meters - - - - -
Individual Weirs - - - -
Weirs Adapters  - - - - -
Complete Weir Kit & Case
FLO-ROD  	  	
                      $2,100
                      $3,000
                      $20 - $44
                      $22 - $85
                      $400
                      $30 - $50
COMMENTS:
The NB manhole meters would appear to be useful for measuring sewer
flows at manholes over a limited range (many manholes will not allow
accurate measurement with the pipe over about half full); however,
these meters seem best suited for use with some better characterized
primary device such as a flume, open flow nozzle, or weir.  The portable
V-'notch weirs may be suitable for their intended purpose, but lack the
range necessary for most flows of interest.  The rod meters should only
be used for making rough flow estimates.
                                  307

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MANUFACTURER:  R. M. NIKKEL COMPANY
               ROUTE 1, BOX B233
               LIVE OAK AVENUE
               OAKLEY, CALIFORNIA  94561
               TELEPHONE (415) 625-3820

PRODUCT LINE:  FLOW RATE TRANSDUCER

DESCRIPTION:

The BPN "FOTOFLOW" Series 800 flow rate transducer is a recently intro-
duced insertion  type device for fluid monitoring in the water industry.
Although described by  the manufacturer as an optical sensing type
transducer,  the  primary element is a freely rotating flow sensing
wheel.  The  wheel rotation is monitored by an optical sensor that of-
fers no impedance to the flow sensing wheel and is easily removable
from the line.   A bi-directional capability is claimed over a nom- ^
inal 100:1 range; accuracy of ±1% of rate and repeatability of ±0.5%
are also claimed.  Prices range from approximately $130 to $350 for the
basic transducer without accessories.

COMMENTS:

Manufacturer recommends unit for use in "reasonably clear" liquids.  It
may find some use as a portable device for attended use in conducting
wastewater surveys, but does not appear at all  sutiable for unattended
use in monitoring  storm or  combined sewer flows.
                                   308

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 MANUFACTURER:
NUSONICS, INC.
9 KEYSTONE PLACE  ,
PARAMUS, NEW JERSEY  07652
TELEPHONE (201) 265-2400
 PRODUCT LINE:  SONIC FLOWMETERS

 DESCRIPTION:

 The NUSonics sonic flowmeter is a frequency difference type device de-
 signed for full pipe flow.   Typically,  it consists of two transducer
 assemblies, two mounting bosses,  a transmitter and 15 feet of cable
 from each transducer assembly to the transmitter.   At the customer's
 option,  transducer assemblies may be supplied fully mounted in a flow
 tube or supplied in kit form for purchaser to install in his own flow
'tube.   The transmitter enclosure may be NEMA 12, NEMA 4, or explosion-
 proof,  at purchaser's discretion.  An optional heater/thermostat for
 the transmitter permits cold weather operation.

 Transducer assemblies are mounted through the pipe in such a way that
 they squarely face each other (Figure A)  and are "wetted" by the liquid
 to  be  metered.   Thus,  the sonic pulse is not distorted by a pipe wall
 and is not subject to any refraction as it enters  the liquid.   It is
 claimed  that this provides  the most reproducible "received pulse" wave
 shape  for best flowmeter performance.   The transducers themselves are
 piezoelectric ceramic disks,  which are  protected by a cover fabricated
 from titanium or from an 8  to 10 mil Teflon coating over aluminum.
 The sonic pulse can be successfully transmitted and received through a
 surprising amount of organic  or Inorganic build-up on the transducers.
 Thus the  NUSonics sonic flowmeter can function long after fouling has
 incapacitated a meter  with moving parts (e.g., turbine meter)  or a
 meter  requiring electrical  contact with the liquid (e.g.,  magnetic
 flowmeter).

 T6  further minimize the potential effects of fouling and/or corrosion,
 the  transducer  assemblies may be  provided with flushing ports  (Fig-
 ure  B).   Combined with Teflon-coated  transducers,  a periodic or  con-
 tinuous flush is  particularly advisable for metering waste treatment
 streams and  solids-laden plant effluent.   The manufacturer notes  that
 the NUSonics  sonic  flowmeter  applies only to liquids or,  in some  cases,
 liquids with  solids  in suspension.  Entrained gas  bubbles  may  inter-
 fere.  In  general,  the liquid must not  excessively absorb  and/or  scat-
 ter  sound.

NUSonics  sonic flowmeters are  available in  sizes from  7.6  to 122  cm
 (3 to 48  in.) in  fully assembled  carbon steel, stainless and fiberglass
flow tubes.  Also available is a  sonic flowmeter kit from which pur-
chaser may convert his own pipe section into a sonic flowmeter in sizes
up to 1.8m (6 ft).
                                  309

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  FLOW
DIRECTION
                Figure A
                Figure B
                     310

-------
NUSonics  sonic flowmeters use  similar  electronics for  all  sizes.  Thus,
price  increases  relatively  little with"size.  NUSonics sonic flowmeters
are assigned meter factors  based on precise transducer spacing measure-
ments  which will yield  an absolute accuracy within ±1%.  Where re-
quired, NUSonics will assist in actual calibration at  an independent
facility  to achieve greater accuracy.  Meter perforrnan.ee is independent
of the inherent  speed of sound of the  liquid being metered but does
vary with the shape and stability of the flow profile  ia the pipe.
Variability for  a given flow condition (repeatability)ris  ±0.2 percent
of reading above a flow rate of 0.3 m/s (1 fps).  Even better repeata-
bility can be achieved  with flow straighteners.  Variability due, to
changes in meter factor with flow conditions (linearity) will be only
±0.75  percent over any  practical flow  range (up to cavitation)  for
Reynolds numbers over 100,000.  Ranges of up to 100:1  may  be achieved.

The NUSonics sonic flowmeter must be installed in straight pipe for
best performance.  For  turbulent flow, the above performance is based
on installations with the sonic flowmeter placed at least  20 pipe dia-
meters downstream and at least 5 diameters upstream of  any elbow, tee,
or obstruction.  Within shorter lengths, the device will yield cor-
respondingly wider errors.

Various flow totalizers, rate meters,  and chart recorders  are available
to receive the transmitter outputs (0-10 VDC; 4-20 or  10-50 mA.

PRICE:                  '.-•••

Prices vary with specifications, but an explosion-proof unit for a
20.3 cm (8 in.) pipe with remote readout costs under $3,000.

COMMENTS:

A major disadvantage of this unit for many wastewater installations is
the necessity for the transmitter to be less than 4.6m  (15 ft)  from the
flow tube.
                                  311

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MANUFACTURER:
OCEAN RESEARCH EQUIPMENT, INC.
FALMOUTH, MASSACHUSETTS  02541
TELEPHONE (617) 548-5800
PRODUCT LINE:  ULTRASONIC FLOWMETERS

DESCRIPTION:

O.R.E. Model 7000 ultrasonic flowmeters are custom designed to meet
each customer's application, and no standard product data sheets or
brochures can be prepared.  However, O.R.E. feels that it has delivered
more of these devices  for open  channel flow measurement than any other
U.S. manufacturer.  The  following  information was obtained by private
letter and  telephone communication.

Basically,  the. Model 7000 ultrasonic flowmeter  can be used either  to
measure line velocities  along a single acoustic path or to measure
total flow  in either open or closed conduits over four or more acoustic
paths and integrating  the line  velocities.  The basic electronics  pack-
age can handle a wide  range of  transducer frequencies  (depending upon
path length) and can sequentially compute total flow for up to four
separate meter sections.

Most of the open-channel systems have been applied  to rather  large
flows, e.g., Columbia  River at  Grand Coulee Dam, Willametta River  at
Portland, Oregon,  etc.  A typical installation  near Hemet, California
measures  an inlet  canal to  Lake Skinner.   This  system gives the volume
of flow directly by integrating the velocities  from up  to nine pairs
of sensors  (depending  upon  depth).

Systems  can be provided for use in-manholes,  but 110V power  is  re-
 quired.   Unattended operation of two weeks is typical,  at which time
 a paper  tape is  changed.  Very little maintenance is  required,  and it
will be  about one year before any failures occur that would  require
 significant repair.  The electronics package  is designed, to withstand
 and operate over a 0°-50°C (32°-122°F)  temperature range.

 Some error (10-15%) can be expected at very low velocities,  e.g.,
 0.03 m/s (0.1 fps), but the systems are quite accurate over the veloc-
 ity range of 0.15-15 m/s (0.5-50 fps).   Meters have been tested in
 0.6m (2 ft) and 1.2m  (4 ft) pipes in the Alden Research Laboratories
 of Worcester Polytechnic Institute with accuracies of better than 1%.

 PRICES:

 Pricing of systems is based upon  the particular design for a given
 application, but a four-path system flowmeter would cost between
 $20,000 and $40,000.
                                   312

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 MANUFACTURER:   THE  PERMUTIT  COMPANY       ......
                DIVISION OF SYBRON  CORPORATION
                E49  MIDLAND AVENUE
                PARAMUS,  NEW  JERSEY  07652
                TELEPHONE (201)  262-8900

 PRODUCT LINE:

 PRIMARY DEVICES -VENTURI TUBES, FLOW TUBES, PARSHALL;FLUMES, PARABOLIC
                  OPEN  FLOW  NOZZLES

 SECONDARY DEVICES - TRANSMITTERS,  RECORDERS, TOTALIZERS

 DESCRIPTION:

 Permutit, a division of  Sybron  Corporation, manufactures a line of both
 primary and secondary devices for  flow measurement.  The primary de-
 vices include both  standard  and inexpensive venturi tubes, fiberglass
 Parshall flumes, parabolic open flow nozzles, and a patented flow tube
 known as the Permatube.  Permutit  also offers a variety of secondary
 instruments such as the  float-in-flume transmitter used with Parshall
 flumes, electronic  and telemeter transmitters, recorders, and
 totalizers.

 Venturi Tubes - Tubes specifically designed for sewage, sludge, and
 trade wastes are the types VS,  VTJ,  and CTJ.  These tubes are differ-
 ential pressure metering devices for installation in closed piping
 systems.  Types VS  and VTJ have low  head loss - less than 22.4 cm
 (9 in.) of water at maximum  flow when used with a 10:1 range meter.
 A claim made for the types VS and  VTJ is that metering by these devices
 is the least affected by upstream  disturbances than by any other
 differential-pressure device.   The simplex type CTJ Venturi tube is a
 one piece construction device of cast iron which minimizes manufactur-
 ing costs and comes in a variety of  sizes to meet most flow require-
 ments.

 The Type VS and VTJ tubes (Figure A) are similar in construction to
 the type VT (cast iron with bronze throat liner) but have special
 design features which make them suitable for sludge and sewage.   The
 type VS design includes a clear water flushing disconnector,  four
manual cleaning valves at both  the main and throat sections (which may
 also be operated pneumatically or hydraulically), and cleanout holes
at top and bottom of each annular pressure belt.  This protects
against fluids containing sediment or substances which may tend to
 clog the piezometer openings.  Continuous backflushing is available as
an option.   This single-tap,  type VTJ has pressure belts at the main
and throat which contain a bushing which permits the use of only one
piezometer tap and cleaning valve at each of these locations; thus,
                                 313

-------
uisr
       TYPE VS -r- FOR SEWAGE
      TYPE VTJ - FOR SLUDGE
            CTJ TUBE
            PLAN VIEW


            Figure A
                 314

-------
 anti-clogging  protection  is  provided  against  sludge  or  floating
 particles.

 The  less  expensive  CTJ design provides  for  single taps  at  the main and
 throat  connections,  and a bronze  throat liner.  A hand-operated bronze
 cleaning  valve is located at each pressure  connection.

 Flow Tubes - Perinutit has developed the Permutube, (patent  pending), a
 flow tube which has  many  performance  advantages claimed for it.  Among
 these are:

     •  Greater accuracy  over wide operating  range,  achieved by
        greater pressure  differential at lower velocity, without
        adversely affecting  overall head loss.

        Low overall  head  loss, measured as  a  percentage of
        pressure differential.

        Stable coefficient over wider operating range of veloc-
        ities  and pipe Reynolds numbers lower than that obtained
        with any conventional venturi tube.

     •  Minimum laying length assures easier  installation  and
        provides greater  flexibility  of location.

The key to this proprietary  design is the ramp and throat  design as
indicated in Figure  B.  It is available as  an insert type, or with
flanged ends in a choice  of  materials and complete range of sizes.
Flanged end Permutubes are made of close-grained, high  tensile
strength cast  iron with a bronze throat liner.  An annulus averaging
ring in the throat section ensures an accurate reading with only a
single tap in  the main.   Tube ends are  standard 56.7-kg (125-lb.) or
113.4-kg  (250-Ib.) flanges.   Insert Type Permutubes are available
with reinforced polyester fiberglass  tube body and cast iron holding
flange or body and flange of integral cast  iron.  Both types feature
a bronze throat liner, annular ring in  the  throat,  and a single tap
at the main.   Holding flange is made  to fit virtually every style
pipe flange.

For sewage handling, the addition of  cleaning and flushing valve may
not be necessary on the Permutube due to the self-cleansing effect of
the flow over the ramps on the Pitot openings.  Where severe sludge
build-up is a possibility, cleaning and flushing valves can be
supplied.

Parshall Flumes - The Simplex Parshall flume  (Figure C)  is constructed
of polyester resin bonded glass fiber with reinforcing ribs to prevent
                                  315

-------
Insert Type; Fiberglass; Cast Iron
Holding Flange, Bronze  Lined
Throat
Insert Type; Cast Iron, Bronze
Lined Throat
 I    i    .      -I
 Flanted End Type; Cast Iron
 Bronze Lined Throat
ACCURACY' f
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BETA RATIO
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0.1 0.2 0.3
Pipe Reynolds Number-Millions
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THROAT VELOCITY FEET PER SECOND
                             Figure B
                                   316

-------
DIRECTION
OF
REINFORCING
RIBS
                                                                CONCRETE
                                                                CHANNEL
                    REIN-FORCING
                    RIBS
    GLASS FIBER PARSHALL
    FLUME
                               Figure C
                                     317

-------
 warping, twisting, or buckling out of shape.  The polyester resins
 are very resistant to erosion from the passage of solids or abrasives,
 making this flume suitable for sewage or industrial wastes flow.  The
 flume is manufactured in integral units.

 Parabolic Open Flow Nozzles - Permutit also markets two types of
 parabolic open flow nozzles, Types S and SFF.  The Type SFF has largely
 superseded the Type S, which featured its own integrally cast sediment
 chamber, a gauge glass and setting scale (for calibration), and a
 manual cleaning valve assembly at the tap location.  The Type SFF
 eliminates these features since its metering float arm rides directly
 on the flow stream.  Most installations are now constructed with a
 transmitter in the pit, with the meter receiver located above the
 metering site or at some distance away in a more protected location.
 Both types are of cast iron construction and utilize the same principle
 of operation.  The interior presents a smooth transition from circular
 to parabolic form, with no obstructions or pockets, straight inverts.
 This permits a gradually increasing velocity through the nozzle, thereby
 tending to provide a self-scouring action.

 Float-in-Flume Transmitter - The Simplex float-in-flume transmitter
 is designed to continuously indicate the flow of sediment-laden
 liquids as it passes through a Parshall flume under gravity conditions.
 A similar device is available for parabolic open flow nozzles.   Liquid
 flow is indicated by the direct sensing of the level of the liquids
 within the flume; flow data are transmitted either electrically or
 pneumatically to a remotely-located flowmeter.

 The transmitter (Figure D)  is mounted directly on the wall of the
 Parshall flume.   A corrosion-resistant "ski" type sensor (float)  rides
 directly on the surface of the liquid flow stream;  it does not  cause
 disturbance on the surface of the liquid or excessive oscillation in
 recording instrument.   As the surface of the. liquid rises or falls,
 depending upon the flow through the flume,  the sensor changes its
 position accordingly.   This movement  produces proportional angular
 movement of the sensor arm and shaft  on which it  is supported.

For electric transmissions, the shaft arm angular movement is trans-
ferred to a stylus riding over a characterized cam which is corrected
for non-linearity.  The resultant linear signal, proportional to flow,
is transmitted every 15 seconds, with a pulse duration varying from a
fraction of a second to approximately 12 seconds.  Three seconds of
each 15-second period are required for the receiver to reset for the
reception of the next signal.

For pneumatic operation, the shaft arm angular movement is transferred
to a. shaft carrying a cam, characterized tojzhe head quantity relationship
                                   318

-------
                                                           •  • i'«
                                                           :•.**•!.
                            Figure D

o£ the flume.  A pneumatic tracing device senses the profile of
this cam and transmits a linear, 3-15 psig pneumatic signal through
an amplifying relay to the receiver.

Advantages of this device include the following:

     •  Reduces installation space

        Faster responses to flow changes

     •  Reduces material costs - eliminates stilling wells,
        connecting piping and fittings, large float and
        cable, back purge system, etc.

Other Transmitters - Several other types of transmitters are offered.
These include the Type K telemeter transmitter, which transmits an
electrical signal through a two-or four-wire system to one or more
systems, and the Type STRR transistorized, force-balance differential-
pressure instrument with a 4 to 20 mADC transmission signal for liquid
flow applications.

Recorders/Totalizers - These include a compact recorder which indicates
and records fluid flow on a rectilinear strip*chart and is actuated
                                  319

-------
either mechanically, electrically, or pneumatically.  Also offered
is the Type STR-3 electronic recorder (solid state receiver) which can
remotely record and indicate flow loss of head, pressure, etc.  The
totalizer can receive differential signals (electrical, mechanical,
etc.) from the primary element.
SPECIFICATIONS:
     Type CTJ Venturi Tube:
Flow capacities ranging from .2456 MLD
(.0649 MGD) to 37.6179 MLD (9.9968 MGD)
depending upon dimensions and type
meters used.

Weights ranging from 16.3 to 247 kg
(36 to 544 Ibs.)
     Flow Tube's  (Permutube): Refer to graphs in Figure B for
                             a comparison of accuracies, head loss,
                             and flow coefficients.
     Parshall Flumes:
     Parabolic Open Flow
     Nozzles:
Throat sizes ranging from 7.62 to
121.92 cm (3 to 48 in.); lengths ranging
from 0.91 m to 3.27 m (36 to 131 in!.);
flexual strength of up to 21,000 psi.

Inlet Diameters (Type S) - 15.2 cm to
106.7 cm (6 to 42 in.)
Flow capacities (Type S) - to 10.295 MLD
(2.72 MGD) for 106.7 cm size.
PRICES:

     Prices not available at the time of this writing.

COMMENTS:

These devices were thoroughly discussed in Section VI and will not be
commented upon here.
                                  320

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MANUFACTURER:
PRODUCT LINE:
DESCRIPTION:
PLASTI-FAB, INC.
11650 S.¥. RIDGEVIEW TERRACE
BEAVERTON, OREGON  97005
TELEPHONE (503) 644-1428

FIBERGLASS PALMER-BOWLUS FLUMES, V-NOTCH
WEIR BOXES, AND PARSHALL FLUMES
Plasti-Fab manufactures several primary devices in a variety of sizes.
For example, Parshall flumes are available from 2.5 cm (1 in.) to
1.2 m (4 ft.) and with either 20.3 cm (8 in.) or 30.5 cm (12 in.)
floatwells attached to either side as provisions for remote stilling
wells.  A head gage is molded into the side of all Plasti-Fab
Parshall flumes for visual checking of flows.  A 2.5 cm (1 in.)
blow-out connection is also provided on the floatwell.  All Plasti-
Fab Parshall flumes are heavily ribbed for free-standing installation,
and they may also be installed as liners in concrete.  They feature
5 cm (2 in.) flanges on ends and top, with heavy angle bracing across
the top flanges.  These basic devices were discussed thoroughly in
Section VI and will not be described further here.
                                  321

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MANUFACTURER:  POLCON, INC.
               AN AFFILIATE OF CARL F. BUETTNER               ^
                 & ASSOCIATES, INC.
               5106 HAMPTON AVENUE
               ST. LOUIS, MISSOURI  63109
               TELEPHONE  (314) 353-5993

PRODUCT LINE:  FLOW TUBE

DESCRIPTION:

The POLCON flow tube is a primary metering element  designed for the
measurement of wastewater flows  in partially  filled circular conduits.
The tube is furnished in  segments for  insertion into existing piping
systems through a manhole or other opening in the piping system.   Fig-
ure A shows a typical flow tube  installation.
             1/4 MAYON TUBING
             FURNISHED BY POLCON
                                              TO AIR SUPPLY AND
                                               INSTRUMENTATION
                                                               LOCAL OR
                                                              'REMOTE
                                                               READOUT
                                                               PERMANENT OR
                                                               PORTABLE
                                                               INSTALLATION
             ••PRECISION ORIFICE
                             Figure A

The POLCON technique  of measuring flow is  based on the establishment of
a fixed relationship  between the depth of  liquid flowing in a smooth
straight  conduit  and  the  rate of flow.   In effect, it allows the
Manning friction  factor "n"  to be factory  determined, and the "POLCON"
conversion tables account for its variability with flow depth.  A uni-
form slope is also established.   A precision orifice embedded in one
segment of the  flow tube  permits the depth of liquid flowing to be
measured  by determining the  air  pressure required to overcome the
height of fluid.

"POLCON"  flow tubes provide  a smooth, continuous liner inside an
existing  pipe and are sufficiently long to permit the bubbler to be
located downstream from the  manhole  at a point where the flow tube and
                                  322

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hydraulic slope are normally parallel.  They are fabricated and machined
in 30.5 cm (12 in.) long segments, eight of which are used in a normal
installation.  For troublesome installations, only four segments can be
used, and at a sacrifice in accuracy.  The entire tube is fabricated of
PVC. plastic, and "0" rings are placed on the exterior surface to prevent
short circuitry of flow.

"POLCON" portable flow tubes are supplied in sizes to fit 15.2 to
45.7 cm (6 to 18 in.) diameter sewer pipes as standard.  Larger or non-
standard diameters can be supplied on request.  On installations where
the nominal size "POLCON" wastewater flow tubes will not pass through
the standard manhole cover, "POLCON" offers large diameter tubes which
are installed as an integral part of the sewer.  Large diameter tubes
are furnished in steel or ductile iron, epoxy lined for lasting service,
and fabricated as a single unit with no decrease in sewer diameter or
carrying capacity.  These are used for new construction or where low-
cost wastewater flow measurements are required in existing large
circular sewers.

"POLCON" also offers a complete line of instruments compatible for use
with their wastewater flow tubes in both portable and permanent con-
figurations.  All portable units are built with rugged, lightweight
fiberglass cabinets measuring 58.4 cm (23 in.) in diameter and 81.3 cm
(32 in.) high.  Model PIP-100 is powered by an external air supply con-
nected to the built-in air control system.  The cabinet contains a
rota/purge meter, a 15.2 cm (6 in.) spring-wound recorder covering
0-38 cm (0-15 in.) of water range.  Model PIP-101 differs only by the
addition of a 14-day gas bottle that is locally refillable.  Model PIP-
102 features an air compressor and electrically-driven recorder, arid
also requires a 110-VAC external power source.  Model PIP-112 combines
the air compressor with a gas bottle back-up to avoid power failure
effects.  Options include a 20.3 cm (8 in.) recorder and a 7 day or
24 hour recorder.
                                   323

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SPECIFICATIONS:

Accuracy:

Flow  Capacities:
Up to ±4%
POLCON
Model #
SFT/PFT - 6
SFT/PFT - 8
SFT/PFT - 10
SFT/PFT - 12
SFT/PFT - 15
SFT/PFT - 18
Sewer*
Dia.
6"
8"
10"
12"
15"
18"
Quantity in GPM*
Slope
1%
178
254
531
977
1575
3358
2%
251
360
751
1382
2227
4749
3%
308
440
920
1693
2728
5817
4%
356
509
1063
1955
3150
6717
4%
398
569
1188
2186
3522
7510
        Metric Conversion Factors:
           Inches x 2.54 s Dia.  in  centimeters  (cm)
          GPM x 3.785 = Liters  per  minute (LPM)
 PRICES:

 A total  POLCON package (including an 8 to 10 inch-tube,  sensor,  and
 liquid level recorder) costs approximately $2,000 -  $800 for  tube and
 $1200 for sensor).

 COMMENTS:

 This device essentially provides a controlled flow section within  the
 sewer in which (hopefully)  the Manning formula can be applied with
 greater  accuracy.   Since slope-area methods such as this are  not well-
 suited for flow determinations in many storm or combined sewers, its
 benefit  would seem marginal at best.
                                   324

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MANUFACTURER:  PORTAC
               MIN-ELL COMPANY, INC.
               1689 BLUE JAY LANE
               CHERRY HILL, NEW JERSEY  08003
               TELEHPONE (609) 429-0421

PRODUCT LINE:  CURRENT METER FLOW TUBES

DESCRIPTION:

PORTAC Flow Tube - The PORTAG Portable Sewer Conduit Flowmeter is a
patented device (Figure A) that has been used successfully by New York
City's Department of Water Resources Industrial Wastes Control Section
for sewer flow measurement.  The meter, shown in the plan view of Fig-
ure B, is designed to create full pipe flow in the sewer conduit, thus
making the area of flow constant.   (A self-damming flap gate, also
shown in Figure B, is provided for  this purpose.)  The only other
variable is velocity and this is measured with an OTT .current (velocity)
meter (shown installed in Figure C).  The number of revolutions made by
the meter's propeller are totalized on a digital counter.  By applying
the specific formula supplied with  a particular system, flow totals
can then be calculated.

As shown in Figure B, suspended deflectors, which are removable, are
constructed immediately upstream of the current meter's propeller.
This is done to reduce or eliminate the possibility of damage to the
propeller by hard, fast-moving objects such as wood.  The deflectors
also generally redirect pliable suspended materials, normally en-
countered in sewer wastes, away from the area around the propeller's
rotation.                                     •             .

Easily mounted on and suspended with a placement rod, the device can
be installed  (or removed) by  only two sewer workers, regardless of
manhole invert contours.  Some of the hydraulic and physical advan-
tages claimed for the PORTAC  flowmeter are:

      •  Velocity of  approach  is not a factor if a high velocity
        propeller is used on  the current meter;

        Sewer grade may be any value;

      •  The system is as good or better than a flume or weir in
        terms of ease of installation; the tube can also be easily
        sealed to  ensure that all flow is being gaged;

      •  The system is unaffected by surcharging or submersion;
        and
                                   325

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326

-------
BEFORE AND
DURING
INSTALLATION
METER IN
OPERATION
                         Figure B
                             327

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o
 0)

-------
     •  The system does not need compressed air or AC power to
        operate, and thus is truly portable.

The flowmeter is fully adaptable for analog metering as well as strip
chart recording.  The standard metering package consists of:  the flow
tube; an OTT Model 10.002 current meter; and a three-digit, battery-
operated counter model (F4).  A five-digit counter (also battery
operated), Model Z100, with other monitoring features* is also avail-
able, at additional cost.  An optional current meter for use with
PORTAC is the OTT Model 10.300 which has provisions for analogue strip
recording.

Current Meters - In the OTT 10.002 standard unit shown in Figure D,
signals are generated by means of a permanent magnet mounted on a worm
sleeve which completes the circuit by way of an impulse device embodied
in the meter following each revolution of the propeller.  The device is
           r
                                                      112.01
                             Figure D
*  e.g., audible indication of input pulses by a loud buzzer.
                                  329

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largely free of restoring forces and may be said to operate virtually
without power.  The diameter and pitch of the propeller to be used is
determined by the maximum flow velocity of the water to be encountered.
A special table is provided to enable proper selection.

Counters - the three-digit F4 counter (type 12.000) counts a maximum of
10 pulses per second and is suited for operation with the OTT 10.002
(C31) current meter, which generates a signal pulse at each revolution
of its propeller.  Two 1.5-volt "D" size batteries serve as the power
source and allow up to 48 hours of continuous operation without battery
replacement.  A stopwatch is used in conjunction with this instrument.

The Z100 five-digit counter is capable of measuring the length of pulse
cycles from voltage-free transmitters (e.g., current meters), up to a
maximum of 20 pulses per second.  It is powered by six 1.5-volt single-
cell batteries sufficient for about 30 hours of operation, assuming
8 hours of operation each day.

SPECIFICATIONS:
        PORTAC Flowmeter (Less Current Meter and Counter)
Accuracy:
Line Sizes:
PRICES:
±3%, when velocity flow exceeds
.027 m/s (0.09 fps)
15.2 to 45.7 cm (6 to 18 in.)
Nominal I.D.
   PORTAC (Less Current Meter and Counter)

   PORTAC Complete with Current Meter and
     Counter
   Optional 5-Digit Counter (Z100)

COMMENTS:
                 $815-$915


                 $1150.00
                 $950.00
Although this unit has been used in some sewers, it does not appear
well suited for general storm or combined sewer applications, since it
must suffer all the deficiencies of a current meter and is available
only in small sizes.
                                  330

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MANUFACTURER:  RAMAPO INSTRUMENT COMPANY
               MACOPIN ROAD
               BLOOMINGDALE, NEW JERSEY  07403
               TELEPHONE (201) 838-2300

PRODUCT LINE:  TARGET-TYPE FLOWMETERS, RECORDERS, INDICATORS

DESCRIPTION:

The RAMAPO Instrument Company manufactures a flow meter probe (the
Mark V) which is reported to be widely used for measuring industrial
wastewater flows.  The company also offers several other flowmeters,
including the newly-developed Mark VI target flowmeters, and a variety
of recording and indicating devices.

Mark V Flowmeter Probe - This device will>measure most process fluids
in pipelines.  This is done by installing a flanged fitting into an
existing pipeline (see Figure A).  The strain gage force sensing ele-
ment of this device has no bearings or other rotating parts.  The
electrical signal can be transmitted to remote locations or used for
indicating, recording, controlling, and totalizing.  The Mark V Flow -
meter measures flow in terms of the dynamic forces acting on a fixed
body in the flow stream.  Bonded strain gages in a bridge circuit out-
side the fluid stream and shielded by stainless steel, translate this
force into an electrical output proportional to the flow rate squared.

A modification of the standard Mark V Flowmeter Probe, a retractable
probe, is also available for pipeline applications.  This particular
device can be installed in or removed from pressurized systems without
causing a shutdown.  The probe can be moved from line to line - even
for widely varying line sizes - for sampling or spot checking of flows.
Materials and specifications are generally the same as those for the
standard probe.

Other Flowmeters - Less suitable for effluent flow measurements is the
Mark V flowmeter for tube end and pipe connection applications.  They
are usable with slurries and some types of abrasive fluids, however.
Accuracy is reported to exceed ±0.5 percent in flow ranges of approxi-
mately 10:1.  Line sizes available are from 1.3 to 15.2 cm (0.5 to 6 in.)
with any standard end fitting, with special sizes supplied upon request.

The Mark VI Target Flowmeter is a new product which has been developed
for measuring flows of dirty liquids, slurries, etc.  This flowmeter
has no moving parts and no cavities to collect particles or entrap
materials that can harden.   Available in a wide variety of line sizes
and configurations, it has operational performance characteristics
similar to the Ramapo Mark V Target Flowmeter.
                                   331

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Figure A
    332

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 Secondary Flowmeasuring  Devices  -  Ramapo markets  several  recently-
 developed recorders  and  digital  flowmeters  compatible with the Mark V
 and Mark VI.

 One type records  flow on an  inkless,  5.1 cm (2  in.) wide  chart.   Sig-
 nals accepted  are typically  0-1  volt  or 4-20 mA.   The scale and  chart
 use square root ruling so that the flow rate signals  originating at
 target meters, orifices,  and other differential pressure  devices can
 be read  directly  in  percent  of flow.  One chart lasts "30  days.   Absolute
 accuracy is ±2 percent.

 Digital-reading flow indicators, with BCD output  if desired, are avail-
 able for reading  in  engineering  units such  as GPM, CFM, and H/s.
 Depending upon the application,  the display can present readings to a
 maximum  of 1999,  3999, or 19999.
SPECIFICATIONS:

Line Size*:

Calibration*:
Accuracy:
Range:


Materials*:

Pressure Loss*:

Input:
Output:
Connections*:
10.16 to 152.4 cm  (4 to 60 in.)
±1%; 2%

±1% full flow (Bi-directional)

Any 10:1 range up  to a line velocity
of 4.57 m/s  (15 fps) maximum

Stainless steel sensing element;
Mounting flange as specified
Usually less than 10 cm (4 in.)
of water
5 to 10 VDC

Up to 20 mVDC maximum or 2.0 mVDC input
for full range flow rate.   Semi-
conductor gages available for higher
output

Terminal strip in explosion-proof
enclosure, or submersion-proof head
and cable
   Mark V Flowmeter  Probe Only.
                                  333

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PRICES:

Mark V Flowmeter Probes (Standard)
     $745 to $1,195 (2% Calibration)

     $960 to $2,300 (1% Calibration)

COMMENTS:

Although useful for some types of wastewater flows, these target-type
devices do not appear suitable for extended use in the storm or com-
bined sewer application.  Their limited range and vulnerability to
impact by debris make all but attended, short-time use appear unfeasible.
                                   334

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MANUFACTURER:  ROBERTSHAW CONTROLS COMPANY
               P.O. BOX 3523
               KNOXVILLE, TENNESSEE  37917
               TELEPHONE (615) 546-0524

PRODUCT LINE:  PARSHALL FLUMES; CAPACITANCE TRANSMITTERS; RECORDERS;
               INTEGRATORS; TOTALIZERS; ETC.

DESCRIPTION:

Robertshaw markets a variety of analytical and measurement devices,
many of which are designed for use with water and wastewater instrument
systems.  Typical of these is the Series F-Flume Flow Measurement
System, which incorporates a circular chart recorder with optional in-
tegrator, or a panel-mounted recorder/totalizer.

Flume - The system (Figure A) utilizes as its primary measurement
device a Parshall "Free Flow" flume, constructed of polyester reinforced
fiberglass with Sanitary Satin finish.  The flume is equipped with a
molded-in capacitance sensing probe that is characterized to provide a
linear output signal directly proportional to flow.  The flume is a one-
piece, completely self-supporting unit ready for installation in con-
crete.  A ruggedized model may be installed in conduits above the ground.
The flume and its associated instrumentation are suitable for many open
channel applications.

Transmitter - A capacitance sensing transmitter (Figure A) can be
installed directly on the flume probe (Model 157), or mounted in a loca-
tion remote from the flume.  No stilling well is required.  Because there
are no floats, moving parts, or mechanical linkages, performance is
enhanced.

Flow Recorders and Integration/Totalization - Flow recording and inte-
grating/totalization may be provided with the Series F system using the
Model 241 circular chart recorder with optional integrator, or the
Model 225/534 recorder/totalizer for front panel flush mounting.

The Model 241 electronic circular chart recorder is available in single
or two pen versions in a weathertight enclosure for surface or panel
mounting.  Optional features include built-in integrator-totalizer and/
or square-root extractors.

The Model 534 Integrator-Totalizer provides continuous integration and
totalization of process signals with respect to time.  Ratio adjust-
ment is by means of a long-scale, thumbwheel dial, calibrated for
linear or square-root signals.  A vertical scale meter displays input/
output signals.
                                   335

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                     MODEL 157
                   Free Flow* Flume
Figure A
   336

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 The Models 157/158 Level Tels (transmitters) are capacitance sensing
 instruments producing standard output current signals and are used
 for continuous level indication or control.
 SPECIFICATIONS:
 Output-. Signal:
 Linearity:
 Repeatability:
 Power:

 Input Signals:
 Accuracy:
 Repeatability:
 Pen Response:
 Power:

 Input Signals:
 Accuracy:
 Repeatability:
 Count Rate:
 Power:
 PRICES:
  Model  157/158  Transmitters
                 1  to  5,  4  to  20, 10  to 50 mADC
                 ±0.25% of  full scale
                 ±0.1% of full scale
                 117/230  VAC or 26 VDC
  Model  241 Circular  Recorder
                 1  to  5,  4  to  20, 10  to 50 mADC
                 ±1.0% of full scale
                 ±0.2% of full scale
                 2  to  20 sec., adjustable
                 117/230 VAC,  50-60 Hz
Model 534 Integrator-Totalizer
                1 to  5,  4 to 20,  10 to 50 mADC
                ±0.375% of full scale
                ±0.1% of full scale
                1000 to  20,000 CPH
                117/230  VAC or 26 VDC
Not available at time of writing.
COMMENTS:

The capacitance gage molded into the Parshall flume offers advantages
for some applications.  Parshall flumes were thoroughly discussed in
Section VI and will not be commented on further here.
                                 337

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MANUFACTURER:
SARATOGA SYSTEMS, INC.
10601 SOUTH SARATOGA-SUNNYVALE ROAD
CUPERTINO, CALIFORNIA  95014
TELEPHONE (408) 257-7120
PRODUCT LINE:  ULTRASONIC FLOWMETERS

DESCRIPTION:

Saratoga Systems Inc., under licensing agreement with Lockheed Aircraft
Corporation, has patented and is producing the "ULTRAMETER", a fre-
quency difference type "ultrasonic" flowmeter which combines sonar and
advanced micro-electronic concepts to measure the flow of any medium
capable of providing a uniform flow profile and propagation sound
waves in an undistorted manner.  This device has a number of applica-
tions in the wastewater field.

The Model 201 Ultrameter provides either an analog output, or a digital
output that is directly proportional to the average speed of a fluid
flowing in a pipeline and which can be related to volume flow rate.  The
measurement system, which employs a pair of non-intrusive diagonally-
opposed transducers mounted directly on the pipe itself (see Figure A),
is independent of the sound speed in the fluid as well as fluid density,
composition, viscosity, and temperature.

Sound  "bursts" are propagated alternately  in opposite directions between
the  two transistors.  Because the upstream signal is delayed and the
downstream signal is speeded up by the moving fluid, the alternate
bursts yield a frequency difference which  is a highly accurate measure-
ment of the  flow (to 0.2%).  The measurement also provides  linearity
even at very low flow rates.

Analog current or digital pulse trains are both simultaneously avail-
able from the  "ULTRAMETER", and can  feed directly to recording and
computing equipment.  These data signals can be scaled  to any desired
output dimensions,  such as  GPM or  cubic feet per minute.

Features  include:

      •  Bi-directional  flow measurement  capability

      •  No  head loss  or obstruction to flow

      •  No  moving parts

      •  No  recalibration after initial factory or inplace
         calibration
                                   338

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                Axial flow section, useful for pipe sizes from
                1/e  inside diameter to 3" inside diameter.
                  Ultrameter transducer receives and emits sound waves.

                                Figure A

         100 percent Solid  State electronics including replaceable,
         interchangeable modules and an automatic failure•alarm
         system


The flowmeter may be employed in pipelines ranging from 7^62 cm (3 in.)
diameter pipes  to open channels.
                                     339

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SPECIFICATIONS:

A,typical 9 cm (4 in.) meter flowing 757 Jl/m (200 gpm) has the fol-
lowing performance and operational characteristics:
Accuracy:

Resolution:

Ranges:
   Tipper Flow Limit

   Lower Flow Limit
Data Format  Options:

   Digital


   Analog
 Power:
 Size:
    Standard Meter Bodies
    w/ Transducers
    Weld-on Transducer
    Installations

 Weight:
    Instrument Package
    Transducers (depending
    on installation)
±0.5% (full scale error with
calibration)

±0.2% (full scale)
100 x Full Scale

0.1 x Full Scale


Positive true logic, TTL compatible
pulse train proportional to flow.

0.5% D/A conversion
Current Source 0-1, 4-20 or 10-50 mA
(Full Scale)
Voltage Source ±1 or 0-5 volts
(Full Scale)
117 VAC, 50-60 Hz @ 1 amp
 0.32 to  46 cm (0.125  to  18  in.)


 10 cm (4 in.) up


 27.2 kg (60 Ibs)

 42.5 g to 9 kg (1.5 oz to 20 Ibs)
 PRICE:

 Typical price in 20 cm  (8 in.) size with remote read-out is $3,680.

 COMMENTS:

 A large  quantity of particulate matter  (as  can be found in raw or un-
 treated  sewage) or heavy concentration  of air bubbles can affect the
 system,  although it is  reported that  up to  50 percent concentrations
 of solids have been handled.   These factors have to be determined in
 advance  consultations with  the manufacturer.
                                  340

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There is no restriction on the transducers, but the line has to be full
of liquid.  The electronic control box can be mounted in any orientation
except upside down, but must be within 15m (50 ft) of the transducers.
This distance can be extended to 30m (100 ft) under special circumstances.

Overall accuracy of this ultrasonic device depends to a certain degree
on the stability and definition of the fluid velocity within the meter
path.  In some circumstances (e.g., in large diameter pipes and open
channels), the flow velocity profile is unstable.  Several statistical
averaging techniques, such as the Gaussian integration method, can be
used with the "ULTRAMETER" to improve accuracy.  However, these tech-
niques are complex and involve additional expense.
                                    341

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MANUFACTURER:  SCARPA LABORATORIES, INC.
               46 LIBERTY STREET, BRAINY BORO STATION
               METUCHIN, NEW JERSEY  08840
               TELEPHONE (201) 549-4260

PRODUCT LINE:  ACTIVE AND PASSIVE ACOUSTIC FLOWMETERS            ^

DESCRIPTION:

Scarpa Laboratories currently manufactures a line of ultrasonic flow-
metering and sensing instruments which cover a wide range of liquid
and gas applications.  Those meters appearing to be best suited for
wastewater applications are the non-contacting, clamp-on passive
acoustic SFM/SFS Series (2, 3, 4, 5) meters (these are the least ex-
pensive) and several more expensive models (e.g., Type II SDL-10,
Type IV SDL-8, etc.) that utilize the time difference principle and
digital computer technology.

Passive Flowmeters - These clamp-on flow indicators utilize the acoustic
emission principal and appear to be usable for liquids, solids, gases,
and slurries.  All models in this series read relative velocity for
liquids and gases and relative mass flow for slurries and solids.  The
"SCARPA-SONIC" device responds, through a microphone, to broadband noise
generated by the moving medium - noises which range from the audible to
the high ultrasonic spectrum.  Filters are provided to eliminate
spurious sounds from sources other than the flowing material.  In the
cases of liquids and gases, the signal produced is an analog output
which is a function of flow velocity; for slurries and powders, it is
a  function of mass velocity.  The sensor element clamps or bonds to the
outside of the pipe wall, and the manufacturer states that their best
sensing locations are at elbows or flanges.  It is further recommended
that they should be located at least 3m (10 ft) away, and preferably as
far away as possible, from pumps or compressors as they may introduce
spurious signals that could pass through the receiver band-pass filters.
Very low flow velocities (e.g., slurries) may be sensed by imposing some
form of "flow spoiler" in the stream such as an orifice, pipe constric-
tions, or even any small projection which does not have to have
rotational symmetry.

This meter may be used for any pipe size, ranging from 0.31 cm  (1/8 in.)
O.D. copper  tubing to 305 cm  (120 in.) or larger pipe diameters.  Milli-
volt, milliampere, and relay  contact closure outputs are available.  The
meter must be calibrated at the site of installation.

Active Flowmeters - The Scarpa active ultrasonic liquid (called
"doppler") flowmeter indicates flow by means of two transducers either
clamped on the opposite outside walls or inserted through the walls of
                                   342  '

-------
any pipe size from 7.61 to 152.4 cm (3 to 60 in.).  The instrument
transmits and receives ultrasonic signals through the pipe wall and
across the flow stream at an angle to the flow.  The actual measurement
is of velocity and is transformed to volumetric flow by means of con-
version tables that correct for pipe wall thickness and internal
diameter.  Units for a specific pipe size can be factory calibrated
to read directly in GPM.

Applications range from non-intrusive flow surveys to flow measurement
and control where the non-liquid contact feature is essential.  The
electronics are housed in an industrial grade Nema 4 gasketed box with
hinged door.

The doppler type units all employ digital computer technology in
processing the information obtained from the ultrasonic "front end.*'
BCD or binary outputs can be provided, as well as 0 to 10 volts, 4 to
20 mA or 10 to 50 mA analog outputs.  Digital flow rate displays are
also available as standard equipment.

All transducers are metal encased and transmit and receive through
resonant metal "windows."  As such they can withstand high pressures
and most corrosive environments.  Materials of construction may be
aluminum, titanium, monel or stainless steel.   Explosion proof housings
are available at additional cost.
SPECIFICATIONS:



Range:


Accuracy:

Reproducibility:

Power:

Temperature Range:
Series SF-( ) Flowmeters
            0.3-1.5 m/s (1-5 fps) to sonic
            velocities*

            Calibrated in place

            ±1%

            117 VAC, 1/10 Amp, 50/60 Hz
            9-V Battery Power available some models
            -40° to + 150°C (Sensor)
            -40" to + 80°C (Receiver)
          "Ultrasonic Liquid Doppler Flowmeters (Typical)
Range:  (Flow velocity)          0.3 to > 9 m/s (1 to > 30 fps)
Accuracy:                        ±2%
   0-100 yA meter indicates relative flow velocity.
   on site to indicate actual flow rate.
                                May be calibrated
                                  343

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Repeatability

PRICES:


SFS-2-RPS

SFM-3-BP



SFM-4-RPS

SFSM-5-RPS

TSL-2-( )
Type SDL-10
Type SDL-8

COMMENTS:
                  ±2%
       SF- Series Flowmeters
Ultrasonic Clamp-On Flow Switch,
with Regulated Power Supply.
Ultrasonic Clamp-On Flow Meter,
Battery Powered
Batteries - $2.75 each extra
(2 required)
Ultrasonic Clamp-On Flow Meter,
with Regulated Power Supply.
Flow Switch, Flow Meter Combination
with Regulated Power Supply
Clamp-On Flow Sensors-Transmitters
(Note:  At least one TSL-2-( )
sensor is required with each
receiver)

Ultrasonic Liquid floppier Flowmeters
(Clamp on unit)
("Wetted" sensors)
   ,  $181.50

     $330.00



     $341.00

     $467.50

     $ 93.50
        to
     $165.00
 $3,500-$5,000
$3,500-$10,000
 Scarpa offers  the only passive acoustic  flowmeters  on  the market  today,
 but  little is  known about their use in a storm or combined  sewer
 application.
                                   344

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 MANUFACTURER:  SIGMAMOTOR, INC.
              .  14 ELIZABETH STREET
                MIDDLEPORT, NEW YORK  14105
                TELEPHONE (716) 735-3616

 PRODUCT LINE:  BUBBLER-TYPE SECONDARY FLOWMETER

 DESCRIPTION:

 Sigmamotor has recently introduced their LMS-400 battery operated,
 open channel flowmeter.  It is a bubbler-type secondary device in which
 a pressure transducer senses the back-pressure experienced by an inert
 gas which is bubbled at a constant flow rate through a tube anchored
 at an appropriate point with respect to the primary device (weir,
 flume,  etc.).  The flow depth is thus determined and electronically
 integrated into the appropriate flow equation.   Appropriate numeric
 values  for the rest of the flow equation are set with two dials on
 the front of the meter.

 The device appears to be extremely simple to set up and put into opera-
 tion.   It can operate up to 122m (400 ft)  from the  measurement site.
 This unit,  which is claimed to be one of the smallest and most accurate
 flowmeters available,  is equipped with a 31-day pressure sensitive  strip
 chart recorder for a continuous record of  flow rate and a six digit
 totalizer reading in gallons to indicate total  flow over time.   Besides
 the flow rate readouts in CFS or MGD,  the LMS-400 can be set to simply
 give depth readouts in either feet or inches.   It is also designed  to
 supply  a flow-proportional signal for an automatic  sampler  and will
 indicate at what time each individual aliquot was taken.
SPECIFICATIONS:

Accuracy:

Power:


Battery Life:

Bubbler Cylinders:



Dimensions:
Weight:
±2% from the theory curve of the
primary device
AC units, 115V
DC units, 12V Lead Acid Type Battery
30 Amp-Hour - 10 days
15 Amp-Hour - 5 days

0.9 kg (2 Ib) Freon R-12 gas cylinders
(two) last for approximately 3 to
4 weeks

34.3x36.8x25.4 cm (13.5x14.5x10 in.)
15.9 kg (35 Ib) with 30 Amp-Hour
Battery
11.8 kg (26 Ib) with 15 Amp-Hour
Battery
8.2 kg (18 Ib)  AC model
                                 345

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PRICES:  $1,750 for AC-DC Unit

COMMENTS:

This small, versatile unit appears to be well suited, in conjunction
with appropriate primary devices (linear, 3/2 or 5/2 power), for many
wastewater flow surveys.  Its complete portability makes it especially
attractive for such use.  Wide range requirements could pose a problem;
although the unit has four range settings, they must be set manually.
                                  346

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 MANUFACTURER:  SINGER-AMERICAN METER DIVISION
                13500 PHILMONT AVENUE
                PHILADELPHIA, PENNSYLVANIA  19116
                TELEPHONE (215) 673-2100

 PRODUCT LINE:  PARSHALL AND PALMER-BOWLUS FLUMES; LIQUID LEVEL GAGES
 DESCRIPTION:

 The American Meter Division of Singer offers,Parshall flumes in sizes
 from 7.6 to 30.5 cm (3 to 12 in.) as standard and up to 2.4m (8 ft) on
 special order.  The flumes are heavily ribbed for free-standing instal-
 lations and may also be used as liners in concrete.  They are fabricated
 in one piece from polyester plastic resin, reinforced by glass mat not
; less than 30 percent by weight, and have a smooth white -surface.   A con-
 nection is available on either side for a bubbler pipe, and a head gage
 is molded into the side of the flume.  For installation in pipelines,
 American also offers Parshall flume end adaptors to make the transition
 from round pipe to rectangular flume and back to round (Figure A).
 Short-section flumes (i.e., no diverging section), are available for use
 where space is restricted and the additional head loss is tolerable.

 The Palmer-Bowlus flumes offered by American feature a trapezoidal sec-
 tion with a flat bottom.  Recommended installation techniques include
 grouting or adhesive bonding.  They are also molded from fiberglass-
 reinforced isophthalic polyester resin with a white gel coat interior
 surface.  The outside surface has clips for anchoring to concrete.  The
 flume includes a built-in stainless steel bubbler tube.

 American offers a number of secondary elements (Figure B) for use with
 V-notch weirs, rectangular weirs, Parshall flumes, and Palmer-Bowlus
 flumes.  Spring-wound,  battery,  or electrical (110 VAC) chart drive
 speeds can be either 24 hours or 7 days per revolution.  Integrating
 instruments use electrical drive charts.

 The American bubbler tube level system utilizes an air pump to pressur-
 ize a capsular pressure element.   A tee is incorporated in the line
 leading to the capsular pressure element to bleed off a continuous flow
 of air (back pressure at the capsular pressure element) to the dip tube.
 The dip tube is open at one end and submerged,  for example in a weir
 with the open end on a plane with the bottom of the weir notch.   The
 air escaping from the open end of the dip tube produces bubbles (air
 pump is adjusted to produce approximately 30 to 90 bubbles per  minute);
 thus,  the air pressure in the dip tube corresponds to the hydraulic head
 of the liquid.  As the liquid head varies,  the pressure in the  tube
 changes.   This tube pressure is  proportional to the pressure variation
 at the capsular pressure element.   Here the movement of the capsular
 pressure element is transmitted  to an integrating stylus and recording
 pen arm which accurately records  a pattern of liquid flow.   The inte-
 grating instrument totalizes the  actual volume measured.   The integrat-
 ing mechanism is a rotating cylindrical cam with a surface corresponding
 to the weir notch characteristic.   Depending upon the position  of  the
 pressure stylus,  the cam actuates the counter drive for a portion  of
 each revolution.   Since all functions  are performed by special  gearing,
 there are no-clutches  to  cause backlash or slippage.
                                  347

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CAULKING
SLEEVE
 Adapters Bolt To Each
« End Of The Flume With
 Stainless Steel Bolts.
•                    Slope With Grout
                    After Installation
EXISTING PIPE LINES
Usually Require The Pipe Invert
To Be Below The Flume Entrance.
                ON NEW PIPELINES
                The Inlet Pipe Invert Should
                Be At Same Elev. As The Flume.
CAULKING COLLARS
Sized 1 "-2" Larger Than
The Pipe To Allow Movement
For Leveling Flume.
                                                                                [—OUTLET PIPE
                                                                                   Must Be At
                                                                                   Same Elev. As
                                                                                   Flume Outlet
                                                                                   Or Lower.
            STANDARD  INLET  AND OUTLET ADAPTERS
                                   FOR PARSHALL FLUMES
        INLET
              End Connections, such as caulking collars, are not shown as size and type may vary.
Fi$f
3"
6*
9*
12*
18*
24"
A
l'-6"
2'-0*
2'-8*
3'-9*
4'-4"
5'-0*
B
12"
l'-6"
l'-9»
2MT
2MT
2'-6"
C
9"
r
8"
10"
10"
7"
D
r-6"
2'-0"
2'-0"
2'-9"
3'-4"
4'-8?
E
• 9"
7"
8"
8"
8"
l'-4"
F
12"
l'-6"
l'-9» -
2'-0"
2'-0"
2'-6"
G
3'-0"
5'-0"
5'-4"
9'-4%"
9'-7%"
9'-10J4"
H
5"
6"
6"
.7"
8"
8"
1
4"
3"
4"
4"
5"
5"
                                         Figure  A
                                           348

-------
                                                  r
-RECORDING ONLY
                           -RECORDING & INTEGRATING
                                                     r-RECORDING & INTEGRATING
                                                      WITH TELEMIKE TO OPERATE
                                                      REMOTE COUNTER
 [-INDICATING TELEMETER
  TRANSMITTER          !
J     r—™^=
SUBUERGE001PTUBE
IS LEVEL WITH THE
BOnOM OF WEIR NOTCH
                                                                                            TELEMETER RECEIVER
                                                                                            RECORDING ONLY
                                              Figure  B
                                                349

-------
MANUFACTURER:  SPARLING DIVISION
               ENVIRONTECH CORPORATION
               4097 NO. TEMPLE CITY BLVD.
               EL MONTE, CALIFORNIA  91731
               TELEPHONE (213) 444-0571

PRODUCT LINE:  PROPELLER FLOWMETERS; TRANSMITTERS, RECORDERS, AND
               INDICATORS/TOTALIZERS

DESCRIPTION:

Sparling Manufactures a variety of propeller-type meters, electromecha-
nical devices and controls, solid state instruments, and telemetering
equipment.   Some of these are suitable, or are potentially acceptable,
for  some wastewater and/or sewer flow applications.  Of particular
interest are the Series 100 meters  (Masterflow wastewater meters) and a
variety of  electrical flow rate transmitters for use with flumes or
weirs or for mounting on meterheads to operate remote recorders, in-
dicators, and/or totalizers.

Sparling offers two styles of wastewater meters - the flanged Masterflow
tube type and the Masterflow Open Flow type  (see Figure A) .  For both
models, application in measuring waste flows is recommended  only after
primary treatment, including waste  or return activated sludge.  These
meters are  not  recommended for raw  sewage or primary sludge  flows.
Therefore they will not be described further.

Secondary Measurement Devices - Secondary devices offered by Sparling
include the following:

      .  Pulse-Rate Transmitters - These  designs utilize  an optical
        pulse-rate generator  to provide  a 0  to 20 PPS signal directly
        proportional  to  flow  rate.

      .  Electronic Transmitters - Measure and  transmit level,  pressure,
        or  other variables.Output signal  accuracy is ±1%.  Pulse
         frequency;  DC voltage,  or  current output modes.

      .  Miniature Strip-Chart Recorders  -  Indicate and continuously
         record flow,  pressure,  level,  or other variables.   Can accom-
        modate solid state or relay-contact output switches  for
         alarm,  status indication,  etc.

      .   Circular-Chart Recorders - Feature 30.4 cm (12  in.)  linear
         charts designed for either 24-hour or 7-day recording;
         25.4 cm (10 in.) indicator scale;  and six-digit  direct-
         reading totalizer.
                                    350

-------
                                             •PUROE CONNECTION
3 STRAIGHTENING VANES  REC-
OMMENDED  WHERE LESS THAN
8 DIAMETERS OF STRAIGHT PIPE
PRECEDE THE METER.
                                                                   3-BLADED CONICAL
                                                                   'POLYETHYLENE PROPELLER
                                                           STRAIGHTENING VANES SPACED
                                                           . .   EQUIDISTANT APART
                           PURGE CONNECTION
                           AND REGISTER HOUSING
                           ON TOP OF DROP PIPE
                           (not shown)
                 PURGE LINE
  RETAINER RING
      SUPPORT ARM
                                                                    DROP PIPE
                                                                             SHIELD
                                            PROPELLER CAP,
                               Figure  A
                                       351

-------
COMMENTS:

Propeller meters are not recommended by Sparling for use in raw sewage
and are unsuitable for a storm or combined sewer application.
                                    352

-------
 MANUFACTURER:  TAYLOR
                SYBRON CORPORATION
                TAYLOR INSTRUMENT PROCESS CONTROL DIVISION
                TELEPHONE (716) 235-5000

 PRODUCT LINE:  ELECTROMAGNETIC FLOWMETERS, SUBMERSIBLE PROBES

 DESCRIPTION:

 Flowmeters - The "MAG-PIPE" 1100/1200 Series electromagnetic flow-
 meters measure flow by Faraday's Law of Magnetic Induction.   A low-
 level, AC signal generated by the movement of a conductive fluid in a
 magnetic field is amplified by a solid-state transmitter which may be
 used directly with Taylor receiving instruments such as controllers
 Recorders, integrators,  etc.  Figure A shows a typical installation.

 The HOOT or 1101T transmitters are used with Taylor 1100L,  1101L
 1200L, 1210L, 1211L,  1240L,  and 1241L sensing heads.  The HOOT is the
 remote unit and can be mounted up to 366 meters (1200 feet)  from the
 sensing head.  The 1101T is  the integral form and is mounted directly
 on the sensing head;  it  produces a 4 to 20 mA DC signal which is linear
 with flow.  The transmitters are completely solid state and  incorporate
 thick film hybrid integrated circuits and an automatic quadrature
 rejection (or null adjustment)  feature which eliminates costly and time-
 consuming start-up.   If  pneumatic output is required,  the 1100L can be
 coupled to a Taylor 737  transmitter.   Teflon is the  standard liner mate-
 rxal used in the "MAG-PIPE"  1100L sensing head,  although a variety of
 other liner materials are offered.

 The recently introduced  Taylor  1210L series uses  self-cleaning electrodes
 to eliminate the measurement problems caused by severe coating buildup.
 The electrode material used  is  Carpenter 20cb-3 stainless  steel, which*
 is ceramic coated for this application.   Only  a conductive "eye"  (Fig-
 ure B)  for signal pickup  is  untreated;  the eye protrudes  into  the higher
 velocity  portion of the process  stream which is  said to have a cleansing
 action on the eye caused by  the  eye's unique geometric  construction.

 Submersible Probes -  Taylor  also manufactures  a submersible probe for
 measuring flow in large process pipes  of  50,8  cm  (20 in.)  I.D. or over.
 The probe, is  a 15.24  cm  (6 in.) magnetic  flowmeter consisting of
 platinum  foil electrodes fired into a  ceramic  tube.  The probe can be
 used with either  a remote or integrally mounted transmitter.  The
 assembly  is welded to a mast which is  fastened to a flange.  When
 inserted  into the process piping, the  ±2% accuracies may be achieved
when a symmetrical velocity profile exists at velocities above 0.6 m/s
 (2  fps).   In addition, compensation can be made for non-symmetrical
velocity profiles by field calibration techniques such as pitot
 traverses, dye dilution,  or other acceptable methods.
                                   353

-------
Figure A
      354

-------
Self-Cleaning Electrodes
                   Figure B
                      355

-------
SPECIFICATIONS:
             1100/1200 Series Flowmeters (Typical)
Accuracy (including Sensing
  Head and Transmitter):
Repeatability  (including
  Sensing Head and Transmitter:
Flow Range:
Sensitivity  (Approx)*:
Output Signal**:
Minimum Process Conductivity:
Power:

Power Consumption**:
Pipe  Sizes:
Weight:
±1% of flow (Sensing Head and
Transmitter calibrated separately)
±0.5% of flow (Integral Mounting
or Sensing Head and Transmitter cali-
brated together)
±0.25% of flow between 0.91 and
4.57 m/s (3 and 15 EPS) (optimum
calibration)
±0.2% of flow

0-0.9 to 0-9.0 m/s (0-3 to 0-30 fps)
300 microvolts rms/ft/sec
4-20 mA, DC
Down to 1 micromho/cm
Il7 VAC, 50/60 Hz or
117 VAC/234 VAC, 50 Hz
12 VA, 11.8 watts
2.54 cm  (1 in.) to 30.48 cm  (12 in.)
6 kg  (13 Ib) - Transmitter;  20.4  kg
(45 Ib)  to 109.0 kg  (240 Ig) -
Sensing Head
 PRICES:   Sensing Heads,  from $935.00 to approximately $5,000
          (MAG-PIPE 1100  Series only)
          Transmitters, Remote Mounted — $810.00
          Transmitters, Integrally Mounted on Sensing Head —  $791.00

 COMMENTS:
 The Taylor line of electromagnetic flowmeters features a number of what
 are claimed to be unique features that extend the utility of  their
 devices.  Electromagnetic flowmeters were discussed thoroughly in
 Section VI and will not  be discussed further here.
 *   Sensing Head only
 **  Transmitter only
                                   356

-------
 MANUFACTURER:  THERMAL INSTRUMENT COMPANY
                41 TERRY DRIVE
                TREVOSE, PENNSYLVANIA  19047
                TELEPHONE (215)  355-8400

 PRODUCT LINE:  THERMAL FLOWMETERS AND FLOW PROBES

 DESCRIPTION:

 The Thermal Instrument Company offers the Model 60 and 60-L thermal
 flowmeters which could be applicable to the measurement of combined
 sewage and stormwater; however,  their Model 62-L thermal mass  flow
 probe and thermal flow probe (no model number)  do not  appear to  be
 suitable for  this application because of the vulnerability of  such
 probes to damage when inserted in effluent and  stormwater  flows
 having large  quantities of suspended materials.

 Model 60 Thermal Flowmeter - This device consists of a single,
 unobstructed  flow tube having no moving parts.   The meter  utilizes
 the thermal boundary  layer principle in which the sensing  elements
 (i.e.,  temperature and flow)  are located on the  outer  surface  of the
 tube and never  contact the flowing medium.   The  flow sensor  is ener-
 gized with a  small amount  of  electrical energy  (less than  one watt);
 the heat conducted off this  element,  by the flow stream, is  directly
 proportional  to  the mass flow rate of the fluid.  Additional sensing
 elements are  located  on the  tube to  compensate and  correct for the
 effects  of fluid  and  ambient  temperature.   It is  reported  that any
 fluid can be metered,  no matter  how  corrosive or  abrasive.   The meter
 is  said  to be not  attitude sensitive and  therefore  can be mounted
vertically to prevent  the buildup  of  solid  particles in slurries.  The
meter can be used with a variety of  standard potentiometric  recorder
or  control devices, standard  industrial and military transducers, and
digital  readouts.

Model 60-L Thermal Flowmeter - The Model 60-L is a  "spool piece" type
meter and  is similar to the Model 60 in basic operation, with one
fundamental difference.  The Model 60-L also has acquired level sen-
sors on  the outside diameter of  the flow tube.  Figure A is a diagram
showing  the location of the level and velocity elements in this combin-
ation meter body.  The product of the readouts provided by the  velocity
and liquid level measuring sensors will give total instantaneous flow
in a partially filled effluent duct,  which usually is so designed that
it will never operate completely full except under emergency conditions.
                                  357

-------
LTZ
•«•• • •

LEVEL

SENSORS
AMAMMflBWM*M"MMM!lKA*
....„_
	 _/yw\ 	 ^2fa
///
/ 1
TEMPERATURE SENSORS *


\
FLC


x
^
W SENSORS


_.. .

=H

                             Figure A
SPECIFICATIONS:
Output:
                   Model 60 Thermal Flowmeter
Flow Rate:
Accuracy:
Repeatability:
Response Time:
Pipe Sizes:
Power:
0 to 10 mVDC signal to operate any
standard potentiometric recorder or
control device (standard)
1 to 5, 4 to 20, 10 to 50 mA or 1 to
5 VDC for recording and control purposes
(optional)
3 to 15 psig or 3 to 30 psig pneumatic
signals (optional)
Digital readout with BCD (optional)
1 cc/min. (minimum); no upper limit
'±1%
> ±0.2% of reading
1/2 sec.
up to  50.8 cm  (20 in.)
115 VAC,  60 Hz, < 20 watts
                                    358

-------
                  Model  60-L Thermal Flowmeter
Accuracy:                        Velocity - 1%

                                 Level - 1%

                                 Overall -2%                   .."-
Other attributes are similar to Model 60.                     ,     \

PRICE:

Prices vary with size and particular specification details; a complete
Model 60-L in a 61 cm (24 in.) size costs around $15,000.

COMMENTS:

The Thermal Instrument Company's products appear very suitable for
measuring storm and combined sewer flows if all the manufacturer's
claims are valid.  No applications data on these fairly new devices
are available for such services.
                                 359

-------
MANUFACTURER:
TRI-AID SCIENCES, INC.
161 NORRIS DRIVE
ROCHESTER, NEW YORK  14610
TELEPHONE (716) 461-1660
PRODUCT LINE:  ULTRASONIC FLOWMETER

DESCRIPTION:

The Tri-Aid Sciences temperature-compensating, ultrasonic flow measure-
ment and transmitter system is designed for use with open channel
flumes or weirs having a 3/2 power flow characteristics.  The model
FC-3-SW ultrasonic transmitter, when correctly installed and calibrated,
will measure  the water depth in front of the flume or weir.

This system consists of two basic components.  The first is an enclo-
sure housing  the electronic control, integrated circuit flow character-
izer, and transmitter.  The second is an ultrasonic transducer  head
for bracket mounting above the water flow at the  flume or weir.  The
transmitter and "head" are connected with a coaxial cable for the meas-
uring signal  and two wires for air temperature compensation.  The sys-
tem generates a high frequency sound pulse from the "head" mounted
above the water flow.  When the  sonic pulse is reflected from the wa-
ter's surface and  received back,  the control interprets the time delay
period  into water  depth and the  integrated circuit function module .
characterizes the  signal  into a  linear  4  to 20 MADC flow signal output.

The  transmitter is enclosed in a 40,6 X 35.6 X 15.2 cm (16X14X6 in.)
oil- and dust-tight fiberglass enclosure  for wall mounting.  The
 explosion-proof  "head"  is encapsulated  in Kynar  to protect  it from  the
 effects of liquids and most  industrial  operating  environments.  The
 output  signal from the  FC-3-SW may be used  to provide a remote  input  to
 a Tri-Aid  integrator  system for  flow totalizing  and  sampling  control.
 It may also be used with indicators,  recorders,  controllers,  and/or
 computers  to meet the customer's system requirements.  The transmitter
 enclosure can be located up to 91m (300 ft)  from the weir  or  flume.
 Typical installation details  are shown in Figure A.   Power requirements
 for the system are:  115 VAC,  single phase,  10 amps,  60 Hz ±10%.

 PRICE:

 Not available at time of writing.

 COMMENTS:

 The 0.9m (3  ft) maximum distance from the face of the transducer head
 to the zero  flow datum is for standard calibration.  For special appli-
 cations, this distance can be. increased up to 6m (20 ft) to meet re-
 quirements for many storm or combined sewer applications.
                                    360

-------
 STN.STL. OR RUSTPROOF
 MATL. REQ'D. (SHIM AS
 NECESSARY TO LEVEL
 TRANSDUCER "HEAD")-

 PREFERRED  LOCATION!
 OF REMOVABLE
 FASTENERS
                                 TYPICAL  .ULTRASONIC

                                 TRANSDUCER  (HEAD>
                                 MOUNTlNGr

                  RIGID CONDUIT TO TRANSMITTER ENCLOSURE

                    LIQUID-TIGHT COklKJECTOR

                         5'TO 10' FLEXIBLE COKJDUIT

                                     LI QUID.-TIGHT  CONDULET
                                     HUB,3/4" N.RT.  FOR
                                     SPLICE OF  COAXIAL
                                     CABLE  4 (2}*IS WIRES.
 LOCATION! OF-!
 FASTENER FOR
 FIRM SUPPORT
 TO PREVENT  -
 VIBRATION OR
 SOUND TRAMS-
 MISSION.
 ULTRASONIC
TRANSDUCER "HEAD"
      \€f MINI
     CAT
       FLOW)
                LOCATE  PER
              FLUME OR WEIR
              FLOW  MEASUREMENT
              POINT (SEE  FLUME
              DATA  PROVIDED
              WITH  FLUME").

* NOTE:
  BOTTOM  SURFACE. OF TRANSDUCER WHEADW
          BE PARALLEL.  TO  LIQUID SURFACE.
           36" MAX.
           CAT ZERO
               /  FLOW)
                           Figure A
                             361

-------
MANUFACTURER:  UNIVERSAL ENGINEERED SYSTEMS, INC.
               7071 COMMERCE CIRCLE
               PLEASANTON, CALIFORNIA  94566
               TELEPHONE (415) 462-1543

PRODUCT LINE:  FLOWMETERING SYSTEMS (CONTROL CABINET,
               RECORDER, TOTALIZER, READOUTS)

DESCRIPTION:

UES offers its electronic FLO/Monitor flow measurement system in several
different configurations - i.e., for permanent installations, remote or
temporary locations, and intrinsically safe installations for "hazardous"
area applications.  Specifically designed for measuring wastewater flow
in manholes, in effluent and influent lines, etc., this completely elec-
tronic system, which utilizes a Palmer-Bowlus flume for its primary
element, does not employ floats, probes, mechanical linkages, or bub-
blers.  The basic unit consists of a control cabinet and the measuring
flume.  The control cabinet contains the electronic circuits, flow
recorder, flow totalizer, power supply, etc.  The measuring flume
carries an embedded sensor element which provides the electronic infor-
mation relating water depth to flow.  Figure A shows a typical temporary
manhole installation.

Measuring Flume - The physical configuration and dimensions of this
primary measuring device  (Figure B) follow  the standard Palmer-Bowlus
concepts.  Its smooth, acrylic-PVC plastic  construction is rugged and
causes little, if any, disturbance or restriction to water flow.  Sizes
to 30.5 cm (12 in.) are stock items; larger sizes may be obtained by
special order.

Flow Rate Recorder - This secondary device  provides a 30-day, continu-
ous strip chart for recording a permanent record of flow variations
 (rate vs time) in the sensing flume at all  times.  Special pressure-
sensitive chart paper is  used.

Flow Totalizer - This six-digit counter displays total flow volume
 through the  flume in units from one thousand to  one billion gallons.

Telemetering - Via a special  operational plug provided with each moni-
 tor, flow rate and total  flow information can be sent to central office
 terminals.   Built-in logic circuits are provided for this purpose.

 Remote Display - Up to  1525m (5000 ft) of 6-conductor, No. 20 gauge
 shielded wire can be provided as  interconnecting cable between an
 optional remote display and  the  low-voltage FLO/Monitor computer
 (Model 8092  only).  The remote  display contains  a  flow rate recorder  .
 and a  flow  totalizer and  an  alarm to  signal excessively high or low
 flow rate.
                                   362

-------
Temporary Location
Model 8091
                              Permanent Installation
                              Model 8090
                     Figure A
                          363

-------
Figure B
      364

-------
SPECIFICATIONS:
                                 Flume
Pipe Size - cm (in.)
10.2(4)
15.2(6)
20.3(8)
25.4(10)
30.5(12)
f 4 1
Length - cm (in.)
26.4(14)
50.8(20)
68.6(27)
81.3(32)
96.5(38)
Max Flow - MLPD (MGD)
.475 (.125)
•95(.25)
1.90(.50)
3.42(.90)
5.32(1.40)
        FLO/Monitor  (All Models unless otherwise  indicated)
Accuracy:
Power:
Size:

  Control Cabinet
  Remote Display Unit
  (8092 only)

  FLO/Computer (8092 only):
Weight:

  Control Cabinet
  (8090/8091)

  Power Supply (8091 only)

  Remote Display Unit
  (8092 only)            ,

  FLO/Computer (8092 only)

Temperature Range:

Price:
.±4%  full  scale

120V 60 HZ
 12V (Rechargeable gel-
     battery  for  8091  FLO/
     Monitor)
30.4x35.6x15.2  Cm
(12x14x6  in.)    .

2p.;3x25.4xl0.2  cm
(8x10x4 in.)

20.3x25.4x10.2  cm'
(8x10x4' In.)
 •9.p7:kg  (20! Ib)


 11.34 kg  (25 Ib)

 -4.54 kg  (~10 Ib)


 ~2.27 kg  (~5 Ib)

 -1° to +49°C (30°/to  120°F)

 Not available at  time of
 writing.
                                365

-------
COMMENTS:

Using a characterized electronic probe embedded in the wall of the
Palmer-Bowlus flume offers many advantages for storm or combined
sewer application.  However, the one-piece design will present size
restrictions due to manhole entry dimensions.
                                 366

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 MANUFACTURER:
 PRODUCT LINE:
 DESCRIPTION:
VICKERY-SIMMS, INC.
P.O. BOX 459
ARLINGTON, TEXAS  76010    ,  .-
TELEPHONE (817) 261-4446       :

ORIFICE PLATES, FLANGES, FITTINGS, AND METERING
TUBES; ASME AND SHORT-FORM VENTURI TUBES; FLOW
NOZZLES; PARSHALL FLUMES; TURBINE FLOWMETERS
 Vickery-Simms  is  a long-established manufacturer of primary flow meas-
 urement  devices.   Each  of  their  product  lines will be discussed briefly.

 Orifice  Plates and Accessories - Vickery-Simms  (VSI) maintains an
 environmentally-controlled atmosphere where concentric, eccentric,
 segmental, and quadrant edge orifice plates are bored to precision
 tolerances in  conformance  with AGA, ISA, and ASME recommendations
 (unless  otherwise specified by the customer).   Each plate is stamped
 with line size, ASA rating, material, and  exact orifice bore.  All
 plates which are  beveled are stamped "inlet" on the square-edged side.

 Sizes available for line diameters are from 1.3 to 229 cm (0.5 to
 90 in.)  in virtually any machinable material to suit the application.
 Types 302, 304, and 316 stainless steel, hastelloy, and monel are
 stocked  for immediate delivery.  Orifice flange unions, fittings to
 allow removal  without interrupting service, straightening vanes, and
 meter runs for highest  accuracy  are also offered by VSI.

 Flow Nozzles - VSI  manufactures  flow nozzles for critical and sub-
 critical flow  in  accordance with ASME standards.  These are available
 in carbon steel,  chromo moly, and stainless steel in sizes from 2.5 to
 76 cm (1 to 30 in.).  For  guaranteed accuracy,  flow-calibrated meter
 runs are also  manufactured.

 Venturi Tubes  - VSI manufactures a number of venturi tubes including a
 fabricated type (welded, not cast) ASME, a short form, and a low
 pressure loss  venturi.  The fabricated, long-form (ASME) venturi is
 lighter in weight and more durable than cast or forged Venturis.  The
 short-form venturi, while offering standard venturi accuracy (±0.75%
 uncalibrated), requires less laying length (four times the pipe diam-
 eter) and produces  only slightly greater unrecovered pressure loss.
 The low pressure loss venturi or flow tube is a special design that
maintains good uncalibrated accuracy (±1%)  but offers only about one-
 fourth the pressure loss of a standard venturi  (typically 3% with a
beta ratio of 0.75).
                                  367

-------
All VSI venturi tiihes are available in a wide range of standard sizes
from 7.6 to 122 cm (3 to 48 in.) and four beta ratios (0.375, 0.490,
0.630, 0.750).  Other sizes and ratios can be manufactured for special
situations.  A partial list of standard materials includes carbon steel,
various stainless steels, cast iron, PVC, and fiberglass.  Interior
coatings of nickel plating, tungsten carbide, or glass lining are avail-
able to suit special applications.  Insert types are offered as well as
flanged and weld-in designs.  Both single pressure tap designs as well
as multiple taps with an interval annulus are offered.

Parshall Flumes - VSI manufactures Parshall flumes, in all sizes, made
of fiberglass, steel, or prestressed concrete.  They are available with
or without a built-in electronic flow element (liquid height gage); rate
indicators, recorders, and totalizers are also available.

Turbine Flowmeters - VSI manufactures insertion-type turbine flowmeters
for use with or without a check valve.   In-line types with threaded or
flanged ends are also available.  They are offered for use in pipe sizes
from  7.6 to 244 cm  (3 to 96 in.).

PRICES:

Prices were not available at  time of writing.

 COMMENTS:

 VSI manufactures a wide line  of primary  flow measurement devices  and
will  assist  customers  in assembling complete flow measurement  systems.
 All of these devices were  discussed in  Section  VI and will not be com-
 mented upon further here.
                                    368

-------
 MANUFACTURER:  WALLACE-MURRAY  CORPORATION   >  .
               CAROLINA FIBERGLASS PLANT
               P.O. BOX 580
               510 EAST JONES  STREET
               WILSON,  NORTH CAROLINA  27893
               TELEPHONE  (919) 237-5371

 PRODUCT LINE:  PARSHALL FLUMES

 DESCRIPTION:

 Wallace-Murray manufactures a variety of products made of fiberglass
 reinforced plastics, including a line of standard Parshall,flumes.
 These flumes feature maximum chemical and corrosion resistance, under
 normal conditions, through their use of polyester resins.  Wallace-
 Murray offers flumes of varying depths and several optional features.
 Throat widths are available from 7.6 to 121.9 cm (3 to 48 in.); lengths
 range from 0.3 to approximately 3.35m (3 to 11 ft).

 A standard feature of the Wallace-Murray flume is a head gage molded
 into the side of the flume at its lower end for the measurement of free
 flow discharges and flows under partially-submerged conditions.  A free
 flow discharge graph is used in conjunction with the gage to determine
 flows under these conditions.  Under submerged conditions, head flow
must be measured at both upper and lower locations.  By using flow cor-
 rection curves, a determination of the flow loss due to submerged con-
 ditions can be made.  Head gages at the second location are optioanl
 and will be supplied upon customer request.

 Optional features of the Wallace-Murray devices include the incorpora-
 tion, on some models, of a 30.5-cm (12-in.)-diameter floatwell (may be
mounted on either side of the flume) or a 5-cm (2 in.) tap for the in-
 stallation of a remote floatwell or bubbler system.  A sanitary white
gelcoat interior surface is also available. . Installation design fea-
 tures of the flume includes the provision for free standing installa-
 tion with additional reinforcing ribs or stiffeners optional for maximum
stability instead of the standard loops for anchoring when used as
liners in concrete.

PRICES:

Prices not available at time of writing.

COMMENTS:

Parshall flumes were discussed thoroughly in Section VI and will not be
commented upon further here.
                                  369

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MANUFACTURER:  WESMAR INDUSTRIAL SYSTEMS DIVISION
               905 DEXTER AVENUE NORTH
               SEATTLE, WASHINGTON  98109
               TELEPHONE (206) 285-2420

PRODUCT LINE:  ULTRASONIC MEASURING DEVICES

DESCRIPTION:

The Industrial Systems Division of WESMAR  (Western Marine Electronics,
Inc.) manufacturers several secondary liquid measurement devices
utilizing the techniques of ultrasonic (sonar in air) ranging.  These
are the FM 9, a noncontact ultrasonic liquid level "flowmeter" for
flumes and weirs, and SLM 9 and SLM 15 ultrasonic devices for the
measurement of liquid levels.  These devices are all readily adaptable
to water and sewage applications.

FM 9 Flow Meter - Actually an echo-sounding instrument, the FM 9
represents a new concept of noncontact weir/flume flow measurement
(actually level monitoring) involving no moving parts or mechanical
linkage.  An all solid-state device, the FM 9 (Figure A) consists
basically of an electronics unit (control box), PVC-encapsulated sensor,
a meter, and a junction box (JIG enclosure).
  FOR:
  RECTANGULAR WEIRS • CIPPOLETTI WEIRS • TRAPEZOIDAL WEIRS • "V NOTCH" WEIRS
  PARABOLIC FLUMES • PARSHALL FLUMES • LEOPOLD-LAGCO  FLUMES
                              Figure A

This device  employs  a sensor, which is  placed  above the liquid  level.
A repetition rate generator  in  the electronics unit triggers  an oscil-
lator  that sends  a signal  through a driver and power amplifier  to the
                                   370

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sensor which converts these pulses into high frequency sound waves.
The sensor directs these acoustic signals downward to the material.
The sensor detects the returning sound wave (echo) and converts it to
an electrical signal.  Precision timing circuits are used to measure
the time delay for the echo to return.  Processing of the electrical
signals converts the pulse transmit time to an analog voltage or current
proportional to the measurement distance.  Output is available which
represents height or flow.  Temperature compensation circuitry neutral-
izes any temperature variations.

SLM 9/SLM 15 Level Monitor - These are short-range liquid level monitors
which are entirely self-contained and are designed to interface with
standard industrial meters, recorders, and equipment of all types.
Solid state techniques, including the use of integrated circuits, have
been employed.

A basic system consists ,pf an electronics board (power supply, trans-
mitter, receiver) and totally encapsulated PyC sensor.  The SLM 9 pro-
vides noncontact level measurement for distances up to 3m (10 ft)  from
the sensor.  Proportional 0-5 volt and 0-1 mA outputs are standard.
Options include:  4 to 20 mA current output; various meters and enclo-
sures ; and five independently adjustable set points that may be set at
desired level points for pump control, alarm indicators, or annunciators.
Operating principles for liquid measurements are similar,  from an
electronic and acoustic standpoint, to those of the model EM 9 flow
meter.
SPECIFICATIONS:

Range (minimum) :


Range (maximum)



Resolution:

Repeatability:

Linearity:

Output Signals:
FM 9/SLM 9 - 41 cm (16 in.)
SLM 15 - 46 cm (18 in.)

FM 9 - 3m (10 ft)
SLM 9 - 3m (10 ft) (liquids)
SLM 15 - 7m (20 ft) (liquids)
within 1%

within 1%

within 1%

FM 9/SLM 9
0 to 5 VDC
0 to 1 mADC
Sensor Beam Pattern:
SLM 15 - 0 to 5 VDC
         0 to 1 mADC (1 to 5, 4 to 20,
                      10 -50 mADC)
7° conical included angle
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Input Power:

Electronics to
  Sensor Remote
  Operation:
Dimensions (Enclosure)
Weight:

  Electronics
  Sensors

PRICES:
110/220 VAC, 50-60 Hz, 10 watts
FM 9/SLM 9 - up to 91.4m (300 ft)*
SLM 15 - up to 152.4m (500 ft)*

30.4x25.4x12.7 cm
(12x10x5 in.)
0.91 kg (2 Ib)
0.45 kg (1 Ib)
Only general cost guidelines can be provided due to the many variables.
Complete systems range from $1,500 to $2,500.  Sensors cost from $125
to $150 and control boards are from $500 to $800.  Enclosures (junction
boxes) are available from $25 to $500, depending upon size and NEMA
rating.

COMMENTS:

Ultrasonic liquid height gages were discussed in Section VI and will
not be commented on further here.
*  Using Coaxial Cable RG620.
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 MANUFACTURER:   WESTINGHOUSE ELECTRIC CORPORATION
                OCEANIC DIVISION
                P.O.  BOX 1488, MAIL STOP  9R3Q
                ANNAPOLIS, MARYLAND  21404
                TELEPHONE (301) 765-5658

 PRODUCT LINE:   ACOUSTIC FLOWMETER

 DESCRIPTION:

 More than  10 years of  research in the flow measurement field by
 Westinghouse has  gone  into  the development of  this acoustic measuring
 system.  The Model L.  E.  (leading Edge)  Flowmeter is so named because
 it uses  only the  leading edge of  an acoustic pulse as a basis for
 determining liquid velocity and volume flow rate.  While this flow-
 metering system was  designed to measure  water  flows, the basic principle
 applies  to most other  liquids as  well, including raw sewage.

 Two  ultrasonic  transducers  are installed in opposite walls of a conduit,
 with the line between  them  at an  angle (45°, for example) with the
 conduit  axis.   The two transducers  simultaneously transmit pulses of
 sound energy through the moving fluid.   The pulse moving with the flow
 travels  the distance between transducers in less time than the pulse
 moving against  the flow.  The system measures  the transit time of the
 faster pulse and  the difference between  the transit times of the faster'
 pulse and  the slower pulse.  Using  these two time measurements, it
 solves two simultaneous  equations in two unknowns - the sound velocity
 and  the  fluid velocity.  Sound velocity  can vary with changes in fluid
 temperature, salinity, and  other  properties.  By measuring sound veloc-
 ity  and  correcting for it,  the system  automatically maintains its
 accuracy for varying fluid  conditions.   Volumetric flow through a con-
 duit is  computed by  integrating the  local fluid velocity over the con-
 duit cross section.  The system does this by measuring local velocities
 along several paths, scaling these velocities for path geometry, and
 summing.  A pair of  transducers is required for each path.   Four trans-
 ducer pairs (four paths) will achieve better than 1% accuracy with any
 practical velocity profile.  Volumetric  flow in an open stream is com-
 puted in a like manner, except that water stage is measured and
 accounted for as it varies.

 Figure A sh9ws a basic acoustic configuration arrangement.   Two probes
 are  shown in the diagram, each with separate transducers and trans-
mitters; however,  in actual practice only one transducer is generally
used  in  each probe, and both probes are  energized by a common trans-
mitter.  The probes provide an unobstructed flow path without head
loss.
                                  373

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                                           PROBE 2
                             figure A

The basic L.E. system consists of the transducers and transducer fit-
tings, cabling, and a console housing the electronic circuitry and
readouts.  Four pairs of transducers are provided for flow in conduits;
in open channel applications, the number of transducer pairs must be
determined by the installation geometry.
                                  374

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SPECIFICATIONS:

Accuracies:


Operating Range:

Power (Console):

Flow Rate:
                                  to  0.1%  (demonstrated)  in  pipes  from
                                  0.3 to 9.14m (1  to  30 ft)

                                  10,000 to 1  (typical)

                                  115 VAC, 60  ±2 Hz,  3 amps, <500  watts

                                  No  upper limit.  Flows  approaching
                                  16,990,000 £/s (600,000 cfs) have been
                                  measured.  Liquid velocities to
                                  >0.5 percent of  full scale.
Dimensions  (Console):             198x63.5x63.5 cm (78x25x25 in.)

Weight  (Console):                 136 kg (300  Ib)

PRICE:  $40,000 up

COMMENTS:

Section VI discusses the advantages  and disadvantages of this type flow-
meter.  Cost, size, and complexity of this system mitigate against its
use for many storm and combined sewer applications.
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                          SECTION VIII

                   SELECTED PROJECT EXPERIENCE
In order to evaluate both standard, commercially available flow meas-
urement; equipment and custom engineered equipment in actual field use,
a survey of recent USEPA projects in the storm and combined sewer pol-
lution control area was conducted.  Several USEPA projects designed
solely to develop improved flow measurement equipment were included in
the survey.  Final reports were obtained where available, but for some
projects only interim reports existed and, in a few instances, tele-
phone conversations had to be relied on.  The projects are discussed in
general chronological order, starting with earlier efforts and finish-
ing with current, on-going activities.

A survey of recent activities of several other Federal agencies in re-
search and development of improved flow measuring devices and methods
is also included herein.  The responsibilities of these agencies include
measurement of water, so they are familiar with flow measurement needs  to
fulfill their own objectives.  In a few cases, these needs include measure-
ment of stormwater and combined sewage.  Contacts with key personnel of the
agencies were made by personal interview, by telephone, and by letter.

CHARACTERIZATION AND TREATMENT OF COMBINED SEWER OVERFLOWS

Reference  (73) describes a study whose general objectives were:   (a) to
develop workable systems to manage overflows from the combined sewers
of San Francisco, thereby alleviating pollution and protecting bene-
ficial uses of local receiving waters, and  (b) to provide the rationale
and methodology for controlling pollution from combined  sewer overflows
in other metropolitan areas of the United States.

Data collection for the project included measurement of  dry weather
flows of the Selby Street and Laguna  Street trunk sewers and measure-
ment of storm overflows from the  two  sewers.  Eight storm overflows
were monitored at the Selby Street outfall  and two were  monitored in the
Laguna Street outfall.  Monitoring included measurement  of rainfall and
discharge.as well as the quality  characteristics of the  overflows.

The tracer dilution method was  selected  for use  in measurement of dry
weather flows.  Pontacyl Brilliant Pink B fluorescent  dye was used for
the tracer, and  quantitative analyses for the tracer were made with  a
Turner Model 110 Fluorometer.   Selection of the  tracer was based on  the
following  advantages:

      a.  Only  small  quantities  of dye are required because precise
         determination of  the dye concentration is possible  at
         10~3  mg/£.   Thus  cost  and quantity requirements are reduced.
                                    376

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     b.  In most sewage flows the "background" of this particular
         dye is not significant.  The amount of tracer does not
         have to be materially increased in order to eliminate
         spurious background effects.

     c.  The tracer is not significantly affected by the presence
         of materials normally found in sewage.

Use of the dilution method did not prove satisfactory for measurement
of the Selby Street overflow.  Uneven distribution of the tracer when
injected resulted from exposed sludge banks, and there was insufficient
turbulence for adequate mixing of the dye.  Because of the resulting
lack of reliable data, a Palmer-Bowlus flume with a 1.22m (4 ft) throat
and 15 cm (6 in.) invert slab, constructed from 16 gauge galvanized
sheet metal was installed.  A continuous record of the upstream water
level was obtained by mounting a Stevens water level recorder, operated
by float, in a stilling well constructed of sandbags.
"Because ofi adequate. nti.XA.ng betow the. pote.nt
othesi method w&6 uubed faofi fitou)
                                               dye. -cn/eatum, the.
                                               at Laguna S&ie.et and no
Because of generally unsatisfactory conditions, several methods were
used for the measurement of storm flow in the Selby Street outfall
structure.  These were:                 ,

     a.  Velocity determination with current meters at a point 15m
         (50 ft) above the outfall structure.  Not considered to
         yield reliable data as the meters were immediately fouled
         with rags and other debris.

     b .  Differential head measurements over the broadcrested weirs
         of the outfall structure.  Because of expected interfer-
         ence by tide gates, the theoretical, head-discharge rela-
         tionship for a broad-crested weir of similar shape was
         used for comparison purposes only.

     c.  Measurement of surface velocities in the outfall structure
         by timing the traverse of styrofoam floats across a meas-
         ured control section.  A factor of 0.64 was applied to
        . surface velocities to convert to average velocity, thus
         accounting for both horizontal and vertical velocity
         distributions.                      ,

     d.  Measurement of vertical velocity profiles in the outfall
         structure with an especially designed current meter having
         low velocity sensitivity.  This was to establish discharge
         values under low head conditions and to check the results
         of the surface velocity determinations.
                                  377

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Water levels in the outfall structure were continuously measured by
means of a "bubbler" gage.  A rating curve was developed from the re-
sults of the surface velocity determinations and the current meter
measurements in the outfall structure.  A theoretical curve computed
from the broadcrested weir formula was approximately 10% larger than
this developed curve.

Flow determinations in the Laguna Street overflow were made by meas-
uring the depth of flow at the outfall sewer and calculating the dis-
charge by means of the Manning equation.  Use of the Manning equation
was said to be justified because the slope of the outfall.sewer is
known, and a uniform reach extends about 210m (700 ft) upstream from
the point at which depths of flow were determined.

STREAM POLLUTION AND ABATEMENT FROM COMBINED SEWER OVERFLOWS - BUCYRUS,
OHIO

Reference (74) contains the results of a detailed engineering investi-
gation and comprehensive technical study to evaluate the pollutional
effects from combined sewer overflows on the Sandusky River at Bucyrus,
Ohio, and to evaluate the benefits, economics and feasibility of alter-
nate plans for pollution abatement from the combined sewer overflows.
A year-long detailed sampling and laboratory analysis program was con-
ducted on the combined sewer overflows in which the overflows were meas-
ured and sampled at three locations, comprising 64% of the city's
sewered area, and the river flow was measured and sampled above and be-
low Bucyrus.                 >

Dry weather wastewater flow measurements were taken of the discharge
from three sewer districts, the influent and effluent of the wastewater
treatment plant, and the Sandusky River at upstream and downstream
gages.  A weir was installed in each of the three trunk sewers, a
90° V-notch weir, a 61 cm (24 in.) rectangular weir, and a 46 cm
(18 in.) rectangular weir.  For two days of the investigation, flows at
the weirs were measured and sampled at 15-minute intervals for 24 hours.
The Sandusky River, upstream and downstream, was measured and sampled
at one-hour intervals for 24 hours.  Also, the wastewater treatment
plant influent and effluent were sampled at one-hour intervals and flow
measurements taken from the plan records.  No problems with equipment
for measurement of dry weather flows were indicated.

To measure overflow during rainfall, rectangular weirs were built at
each of three overflow points.   The weirs were constructed of one-inch
plywood, which was bolted onto (steel) angles imbedded in concrete.
The weir plates were 2.4, 4.9,  and 3.0 meters (8, 16, and 10 ft) long
for Numbers 8, 17 and 23 overflows, respectively.

Water level recorders were mounted in instrument shelters 107 cm
(42 in.) behind the weirs.  The recorders were Stevens Type F Recorder,
Model 68, with a 24 cm (9.6 in.) per day time scale and a 1:2 gage
                                   378

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scale.  All recorders were equipped with automatic starters which would
start the clocks at predetermined water levels.

A continuous record of flow in the Sandusky River above and below
Bucyrus was obtained for the study period.  An existing recording gage
operated by the U.S. Geological Survey located at the first bridge be-
low the wastewater treatment plant was utilized for downstream flow
measurements.  A new gaging station was installed on the river 91m
(300 ft) upstream from the first overflow point of the combined sewer
system.  A rating curve for the gage was plotted using standard gaging
techniques.  The recorders used at both gaging stations were the
Stevens A35, with 1:6 gage scales.  The time scales for the gages were
12.2 and 6 cm (4.8 and 2.4 in.) per day, for the upstream and down-
stream gages, respectively.

No specific problems with flow measurement equipment were reported.
However, a tabulation of overflows indicates that no record was ob-
tained at Numbers 8 and 23 overflows during some periods.  Reasons for
this loss of record were not given.  No check on the accuracy of the
records was made available.

ENGINEERING INVESTIGATION OF SEWER OVERFLOW PROBLEM - ROANOKE, VIRIGINA

Reference  (75) reports on the results of investigations of 25% of
Roanoke, Virginia's separate sanitary sewer system, on the amounts of
infiltration for various storm intensities and durations, and on the
amounts of sewage overflow from the system.

Flows in three sanitary sewer interceptors, and streams draining the
corresponding basins, were gaged during storm events to measure infil-
tration and runoff quantities and to establish their relation to rain-
fall intensities and durations.  After significant variation in dry
weather flows was observed, continuous monitoring of flows in the in-
terceptors was maintained.  Overflows bypassing the Water Pollution
Control Plant were measured during rainfall events.

Sharp-crested weirs were used to measure flows in two of the streams.
In the third stream, a stage-discharge curve was developed from the
Manning formula using the measured hydraulic characteristics of the
stream.  In two of the interceptor sewers, and in the Water Pollution
Control Plant overflow, a stage-discharge curve based on the Manning
formula and the measured hydraulic characteristics of the sewer were
used to convert depth measurements to flow estimates.  In the third
interceptor sewer, dry weather flows were estimated using the Manning
formula, but during rainfall events the sewer became surcharged and
overflow was measured by means of a weir installed in the side of the
manhole wall.

No problems with use of the streamflow measurement devices and methods
were noted.  However, accuracy of measurements with use of the Manning
                                   379

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 formula  in the natural  stream channel photographed must be considered
 very poor.  A photograph of one of the weirs used for streamflow meas-
 urement  shows a  significant accumulation of trash and debris on the
 weir.  Under  this  condition,  accuracy must be considered poor.  Hydro-
 graphs indicated that two of  the  interceptor sewers were surcharged
 during many of the storms, and a  record of discharge was not obtained
 during those  periods.

 Water levels  at  the gaging sites  were recorded by means of six float-
 actuated,  continuous water-level  recorders manufactured by the Instru-
 ments Corporation  (now  a part of  Selfort Instrument Company), and one
 pressure type recorder  manufactured by the Bristol Company.  After the
 float-actuated recorders were serviced and supplied with an expanded
 time scale, they performed satisfactorily for the duration of the pro-
 gram.  During dry-weather periods, the bubbler pipe in the Bristol re-
 corder collected debris and required frequent cleaning.  Because of
 this maintenance problem, it  was  replaced with a float-actuated, con-
 tinuous  water-stage recorder.

 COMBINED SEWER OVERFLOW ABATEMENT ALTERNATIVES - WASHINGTON, B.C.

 Reference  (76) reports  on a project whose objectives were to:  (a) de-
 fine the characteristics of urban runoff in the subject area; (b) in-
 vestigate the feasibility of  high-rate filtration for treatment of
 combined sewer overflow; and  (c)  develop and evaluate alternative meth-
 ods of solution.

 Investigative activities included field monitoring of combined sewer
 overflows at  two sites, and of separated stormwater discharges at one
 site.  The monitoring program was conducted over a period of about
 six months, April 1 to  September  23, 1969.

 Selection of  a satisfactory technique for flow measurement presented a
 problem.  Weirs were not used because backwater elevations would have
 caused surcharging and  flooding at the expected high flow rates.
 Depth of flow measurements with the use of a steady state empirical
 equation such as the Manning  equation for calculating flow was not used
 because  flow  conditions were not  steady state during periods of storm
 runoff.  The method selected was use of lithium chloride as a tracer
 in a procedure similar  to that of the salt dilution method (continuous
 injection type).  Use of a lithium salt is said to improve the techni-
 que because the background of lithium in wastewater is usually low, and
 because  lithium  concentrations at fractional parts per million levels
 can be accurately and conveniently determined by atomic absorption or
 flame emission spectroscopy.   The slope-area method was used as a check.

A number of difficulties experienced in use of the equipment resulted
 in loss of flow record during several major storms.   Greatest trouble
                                  380

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was in clogging  or damage to the submersible pump  used to collect sam-
ples of wastewater required for measuring lithium  chloride concentra-
tion.  Flooding  of one of the lithium chloride  release stations caused
damage to the bubbler instruments used to measure  water stage, to the
lithium chloride release system, and to other equipment.

Flow rate estimates based on depth-of-flow measurements and the Manning
formula were compared with results of the tracer method.   Only a very
general correlation with significant spread resulted.   Large differ-
ences in flow were attributed to inaccurate measurement of depth of
flow and the assumption of steady-state conditions inherent in Man-
ning's formula.

URBAN RUNOFF CHARACTERISTICS       „

Reference (77) is an interim report on investigations  for the refine-
ment of the comprehensive EPA Storm Water Management Model.
       :              -                ,      "•> l.              .   ' '     '  -    •
"Vetaile.d information on the. watestAhe.d chatacteAi&tic& and data on >um-
ofifi quantity and quality have. been compiled faiom a one. ye.ax. Atudy oft a
combined &eweji wateA&heJd oft apptioxAmateJly 2380  a&teA -in Cincinnati.,
Ohio.  Collection oft the&e. data i* planned to continue, oven. a thfiee.
     period."
Flows at three  sites in the sewer watershed were monitored.  At two of
the sites, flow was actually measured in two  tributary sewers immedi-
ately upstream  from their junction.  The third  site was at the outlet
of the watershed;  thus, five sets of flow measuring equipment were
used.
"The. i&ow mejOAutung  appanatu& comi&t& o£ a comptieAAon.,  a manometesi,
and a Taylox. pn.eAt>un.e.-type. necoJideA.  Thl& n.e.do^dnfi operate* by me.as>~
u>u.ng tke. pti&A&uJKi. due. to the. de.pth and veZoc^ty o£ wateA £lou)j.ng -into
the. pipe, by  bubbting OAJL through a tong tube. JMAeAted tnto the. wateJi.
The. gage..sie£ejaAeA  cuJt at a constant pieAAute. and a& the. de.pth and the.
veZoc^ity o£  fitow change* , the. pJieAAute. dsL^esizntial AJ> tie.conde.d on a   '
cAJicjuZcvi chaJit wi  sincheA ofi waiesi.  ThiA ptieA&uJie. di.6fieAe.ntLal *A act-
ually the. £pe,cA,{i
-------
Apparently, the value of slope used in the Manning formula was that of
the sewer line at each of the five measuring sites.  A photograph in
the report shows a heavy, metal, top-hanging gate at the outlet of the
sewer watershed.  The outlet flow monitoring site is described as about
6m (20 ft) upstream from this gate.  If this is the case, flow past the
site probably would not be uniform, and the Manning formula would not
be applicable.

Flows in the two pairs of sewers just upstream from'their junction with
the two sewers to be monitored would be controlled by the slopes of
each of the two monitored sewers rather than the slopes of the four
tributary sewers immediately upstream, which were the slopes in the
Manning formula to compute flow.  In any case, water surface slope is
more properly used with the Manning formula than is the sewer slope.

Plotting of storm hydrographs for the measured sites discloses a number
of serious inconsistencies in the data.
STORM AND COMBINED SEWER POLLUTION SOURCES AND ABATEMENT
GEORGIA
ATLANTA
Reference  (78) reports on a study of six urban drainage basins within
the City of Atlanta, Georgia, served by combined and separate sewers,
to determine the major pollution sources during storm events.  Rain-
fall frequency analysis and simulation techniques were utilized to ob-
tain design criteria for alternative pollution abatement schemes.

Measurements of flow were made of three major overflows, as well as of
the interceptor sewers originating at these points of overflow.  Three
branches of South River were measured, as was the South River main
stream at  four points.  A bypass at the interceptor entering one of the
wastewater treatment plants was measured.

Data were  collected from January 1969 until April 1970.  Continuous
flow monitoring was maintained at the river and its tributary stations,
and in the interceptors where dry weather flow characteristics were of
interest.  Event monitoring only was conducted of overflows and of the
bypass to  the treatment plant.

Rating curves for all gaging stations were developed by stage-discharge
measurements with current meters.  Either Price Type AA or Pigmy Type
current meters were used.  Some discharge measurements were verified
by alternate methods or formulas, but results of these verifications
are not given.

Stevens Type F water level recorders were used throughout.  Gaging sta-
tions were reported to be constructed in accordance with established
U.S. Geological Survey practice.  For flow level recording at intercep-
tors, scow floats were installed at manholes a short distance downstream
from regulators.
                                   382

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Although probable accuracy of the records collected was not reported,
an indication of their accuracy is available, based on one of the gag-
ing stations in the project which was operated by the U.S. Geological
Survey.  This station, having a drainage area of 3.86 sq km (1.49 sq
mi), had been operated since October 1963, or for more than six years.
The greatest flow measured by current meter during the period was
5947 1/s (210 cfs), but the rating curve was extended to 23,220 1/s
(820 cfs) by computation of flow through a culvert.  Records at the
station are stated by the USGS as poor, with no qualification.

STORMWATER PROBLEMS AND CONTROL IN SANITARY SEWERS - OAKLAND AND
BERKELEY, CALIF.

Reference (79) describes an engineering investigation conducted on
stormwater infiltration into sanitary sewers and associated problems in
the East Bay Municipal Utility District, Special District No. 1, with
assistance from the cities of Oakland and Berkeley, California.  Rain-
fall and sewer flow data were obtained in selected study sub-areas that
characterized the land used patterns predominant in the study area.
Results obtained were extrapolated over large areas.

Palmer-Bowlus flumes were installed at three of the ten metering sta-
tions established specifically for the study.  These flumes were con-
structed of stainless steel and were designed to fit the respective
sizes and shapes of the sewers.  They were mounted in the outlet sewer
from the manholes so that head measurements could be made at the proper
distances upstream from the throats.  Wooden channel extensions through
the manholes were installed to prevent water spreading out in the manhole
as depth in the sewer increased.

At seven of the new metering stations, 90-degree, V-notch weirs were
installed.   These were constructed of marine plywood and covered for
additional water resistance with two coats of polyurethane finish.
For ease of installation, a channel closure was provided.so that it
could be easily slipped down into the flowing sewage and quickly bolted
in position after installing and sealing the actual weir plate.
Stevens type 2A35 water stage recorders were used at three weir loca-
tions where submergence of the weir was anticipated.  These recorders
were selected for the ability to record two liquid levels simultaneously,
upstream and downstream from the weir.

Taylor pressure recorders were installed at the other seven new meter-
ing stations.  With these recorders, liquid level sensing consists of
measuring the back pressure from a continuously purging nitrogen gas
bubble system.
                                   383

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In several cases, equipment was installed in manholes near the centers
of streets, thus complicating the installation and use of equipment.
Otherwise, no problems were noted with the use of the equipment at the
newly established stations.

The flow rate at two pumping stations was determined by means of a
system-head curve for the station which gives the discharge rate for
each pump or combination of pumps.  A recording ammeter was attached to
the pump electrical leads to indicate the total number of pumps running
at any given time.  Relief overflow at one of these pumping stations
was measured by means of a broad-crested weir and a wet-well liquid
level recorder.

A third pumping station was equipped with both a wet-well liquid level
recorder and a flow recorder.  The primary device for the flow recorder
was a venturi flow tube mounted on the discharge manifold of the pumps.
                                               Jiir
The influent pumping station at the water pollution control plant was
equipped with individual flowmeters on each pump discharge which were
connected to a combined flow recorder.  The primary devices for the
flow recorder were the discharge weirs in the grit chambers which re-
flect the respective pump discharge rates.

A pumping station relief overflow structure was provided with a flow
measuring device for measuring the volume of water that overflowed.
The 'flow measuring arrangement consisted of measuring the liquid levels
on both sides of a rectangular tide gate and extracting the flows from
the manufacturers rating curve.  Because of difficulties in installa-
tion and operation, no usable flow measurements were obtained during
periods of overflow.

DISPATCHING SYSTEM FOR CONTROL OF COMBINED SEWER LOSSES

Reference (80) describes a regulator control system which is said to
demonstrate impressive reductions in combined sewer overflow pollution
of the Mississippi River in Minneapolis and Saint Paul.

A mathematical model has been prepared that will, using rain gage data
for inputs, (a) perform rainfall runoff analysis; (b) divert combined
sewer runoff hydrographs at the regulators; and (c) route the diverted
hydrographs through the interceptor system.  This model will assist in
operation of the system to retain combined sewer flows and utilize the
maximum flow capacity of the existing interceptor sewer system.

The project includes a computer-based data acquisition and control sys-
tem that permits remote control of modified combined sewer regulators.
Data from rain gages, regulator control devices, trunk sewers and in-
terceptors, and river quality monitors provide real-time operating
information.
                                   384

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Water  surface elevations in the system were monitored  at  about
48 points  by the installation of bubbler gages employing  a pressure-
carrying tube installed in the sewer, an air-supply  cylinder,  a bub-
bler,  a  pressure transducer, and a telemetry unit for  transmitting data
to a central location.  This equipment provided information on the fre-
quency and duration of overflows.  Because flow rate was  not measured,
data on  the volume of overflows were not thus determined.

Flow in  each of the three Minneapolis interceptors at  the
Minneapolis-St. Paul city line> was metered by dual  venturi meters in
each interceptor.   This equipment, which was in use  prior to the sub-
ject study,  provides information on the effectiveness  of  the program to
use the  interceptors for temporary storage of combined sewage.   Flow
data in  the interceptors served to provide a check on  the accuracy of
rainfall runoff modeling.  Probable error of flow measurement  by the
venturi-meters was not discussed.

PRECONSTRUCTION EVALUATION OF COMBINED SEWAGE DETENTION FACILITIES

Reference  (81)  presents the result of a lengthy study  of  combined sewer
flows  in Somersworth,  New Hampshire prior to construction of detention
facilities.   "In o&deA to gat /ie.a&onabty ac-cufiate. and  sieZlabte. fitow
mea&u>ieme.nti>  i£ wa& n.e.c.eAt>any to >tep£o.ce a Auction ofi  the. outfall witin
a. weAA pit taAge. e.nough to provide, a. &CUA amount ofi  &tWUing behind the.
weJA."   This  weir  pit was 1.8 x 1.8 x 7.5m (6x6x24.75  ft),  and  the weir
was located  5.6m (18.33 ft) from the inlet.

Three  different 0.63 cm (1/4 in.) thick steel plate  rectangular weirs
with crest lengths of 0.3,  1.2, and 1.7m (1, 4, and  5.6 ft)  were used,
the 1.2m (4  ft)  one being employed for all but three months of  the
year-long  study.   The design was such that the different weirs  could be
changed  easily  in  several minutes.  The main difference in the  1.2m
(4 ft) weir was that its crest was elevated 1.2m (4  ft) above  the floor
of the weir pit as opposed to 0.76m (2.5 ft) for the other two.   This
weir was constructed after initial operation with the  0.3  and 1.7m
(1 and 5.6 ft)  weirs,  and "observation of high flow  rates  using the
5.6' weir  indicated that it was desirable to increase  the  stilling in
the weir pit  by raising the crest height."

"Head me£U>uAeme.nt& oveA the. 12" and 5.6' weAA& weAe. made. u&tng  an ain
operated FiAzheA and PotteA n.e.c.ofideA.   A &toat 'operated. ttvanAmitteA and
Ae.c.oAdeA manufiactuAe.d by the. Pe.nn/Mea&usie.-JlLte. fl-tv/ci-ton o£  Badge*.
Manufacturing Company WA u&e.d &OA hzad mea&ust.emewti> ovesi the. 4'  umJi
Both n.e.o.o>ideA&  weAe. &et up to u&e. 24 houA,  12" d^LameteA chant*.   The.
FiAaheA and ?ofiteA ie.c.oft.deA c.hants> had a Jiang e. oft 0 to 20 Inches  ofa
head,  and  the. Pe.nn/Me.a&uAe.-'ftite. Re.c.ofideA chasttA had a Aange. ofi  0  to
30
                                   385

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"F£ow Junto the. w&it pit UXM> &uch that &omz tun.buJte.nce. wo6 cueate-d
the, weAJi pit.  Thi& caused the. &low Jie.coKdesiA to paint out he.ad
uM.ement& Jin &hont vertical Atx.ok.eA i.nt>tead oft a. smooth Lena.  ThiA  con-
dition wa& cowie.cted 06 much a& po&Aibte. by the. addition oft the.  4'  weJji
which had a, csiz&t 18" higher than. the. 12" and 5.6' taeMu>.  The. added
depth o& ttoateA -in the. weAJi p did not appeal to upA&t the. hydraulic
chaiajcteAi&tic&  ofi the. taeAJU>.  However,  be.£osie. any sampling paogaanu>
we/ie undertaken,  the. kludge, buuitd-ap wa& totaJULy amoved fyiom behind
the, weJJtA in ondesi to obtain accunate. c.hemic.at and bio£ogic.al chafiao.-
          ojj the. combined sewage, ^£ow.  The. actual Aludge. baiid-ap
      occuA within a couple. o£ day* afateJi the. i.n&tatiati.on o£ a  weAJi.
The. majo/tity o&  Aludge. Jbn. thiA combined Aewage. faJLow c.om>i&ted oft Q>iit
with a &malt percentage. o& ofiganic matte*.."

Head measurements were "... converted to flows using appropriate for-
mulae for the rectangular weirs used in the weir pit."  By this  it  is
assumed that the Kindsvater-Carter equation was used rather than the
Francis formula,  which would require corrections for both less than
standard contraction and velocity of approach much of the time.   For
example, at the  maximum head of 0.6m  (2 ft) on the 1.2m  (4 ft) weir
(any greater head would overflow the 1.8m deep weir pit) the Kindsvater-
Carter equation  indicates a discharge of around 91 MLD (24 MGD), whereas
th.e uncorrected  Francis formula yields approximately 83 MLD  (22  MGD),  a
10% difference.   The maximum discharge for the 1.7m (5.6 ft), as com-
puted assuming the recorder's full 51 cm (20 in.) of head was used, is
approximately 98 MLD (26 MGD).  Maximum flow rates recorded with the
1.2m (4 ft) weir of from 99 to 148 MLD (26.2 to 39.0 MGD) are reported
but not explained.  It is possible that the 148 MLD (39.0 MGD) dis-
charge was estimated but not so indicated.  The point is that high  ac-
curacies should  not necessarily be expected with the given installation
at the higher flow rates.

URBAN STORM RUNOFF AND COMBINED SEWER OVERFLOW POLLUTION - SACRAMENTO,
CALIFORNIA

Reference  (82) contains the results of a program to develop a general
method for determining the extent of pollution resulting from storm-
water runoff and combined sewer overflows occurring in an urban  area,
and the application of this method to the City of Sacramento, California.

Combined sewage  and stormwater in the system were characterized  by  col-
lecting samples  and measuring flows at each of 19 sampling locations
during six wet weather periods.  The intention was to collect, as nearly
as practical, at the commencement of rainfall, three hours thereafter,
and approximately 12 to 18 hours after the commencement  of sampling.
                                    386

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 However, comparison with rainfall records  indicates that the first data
 of each storm period were not collected until  the time of maximum rain-
 fall intensity, or later.

 The wastewater flows were established at manhole  sampling stations by
 use of the Manning formula.  The coefficient of roughness was assumed
 to be 0.013, a design value used by the City of • Sacramento Engineering
 Department.  The value of S used was the measured slope of either the
 water surface or the invert.  Because of difficulties  in making the
 required measurements for determination of slope,  flow data at three of
 the stormwater,runoff sites are not considered to be reliable.   None of
 the computed wastewater flows at manhole sampling stations were checked
 by means of flow measurement equipment.        ;

 For design purposes,  the peak stormwater runoff flow in each of the in-
 dividual pipes comprising the Sacramento collection and conveyance sys-
 tem was estimated from rainfall records by use of  the  rational method.
 These estimated flows for a full pipe condition can be checked at three
 locations with computed flows at the manhole sampling  stations.   They
 differ with the computed flows by -6, +4, and -32 percent.   This  agree-
 ment is exceptional,  particularly as these are the  three locations where
 the computed flows are not considered to be reliable.

 STORAGE AND TREATMENT OF COMBINED SEWER OVERFLOWS

 Reference (83)  describes a project to demonstrate the  feasibility and
 economic effectiveness of a combined wastewater overflow detention basin.

 "A paved asphalt detention ba&in with, a AtoJiage. volume. o&  S.66 acA.e.-6e.e£
 wat> con&tfiacte.d at Chippewa fall*,  Wi&con*in to Jie.ceA.ve.  avzufilou)  £tom a
 90-acJie. combined &WQJI onea Including all o{> the. central ba&ine**  di&-
 &uct.   The. AyAtem wa& designed *o that the. &ton.e.d combined Aewage. could
 be. pumpe.d to the. wa&tewateA treatment plant when  precipitation *ab*ide.d.

 Vusiing  1969, due. to dty weather,  the. pond x.e.c&ive.d only *ixte.en di&-
 chasigeA,  but completely filled twice, and ov&tfilou} to the. fiive*. occuflAed.
 Voting  1970, theAe. weae. 46  di&change*  and the. pond \JUUL
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and a rating curve for the flume, which was approximated in four linear
sections.  Discharges indicated by rainfalls on eleven different occa-
sions were missed due to the recorder being out of order.  Thus, eleven
percent of the runoff events were missed.

Overflow from the 'pond to the river was measured by a 6.7m (22 ft) long
sharp crested weir located in the overflow structure.  The weir head was
measured by a Stevens Type A35 water-level recorder with a cylindrical
float.••  The chart time scale was 24.4 cm (9.6 in.) per day and the gage
scale was 1:6.  The recorder was out of order during one of the three
overflow events which occurred during the period of project operation.

Flows to the wastewater treatment plant'were measured by a meter in the
plant which was not described.  Apparently, this record is complete.

A THERMAL WAVE FLOWMETER FOR MEASURING COMBINED SEWER FLOWS

Reference (64) is a final report for a project to study the application
of thermal techniques to the measurement of flow rates in combined sew-
ers.  The volume flow rate was to be computed as the product of average
flow velocity in the sewer, and cross-sectional area of flow as deter-
mined from a stage measurement.

The use of flush-mounted hot wire or hot film anemometers in a direct
reading mode for measurement of average flow velocity was extensively
investigated.  It was concluded that application of hot film anemometry
techniques to commercial application of measuring sewer effluent for ex-
tended periods of time was not feasible.  Major reasons for this con-
clusion are:  (a) changes in calibration occur due to contamination
film build-up; (b) breakdown of protective coatings over long periods of
time;  (c) change in calibration that occurs due to dissolved gases
coming out of solution and depositing on the film element as bubbles;
and (d) the physical vulnerability of available probe configurations
combined with the difficulty of continuously measuring average velocity.

The thermal wave flow measurement system as developed incorporates five
thermal sensors mounted on the inside periphery of the pipe.  Measure-
ment  of the average flow velocity in the pipe is obtained by averaging
the longitudinal propagation velocities of the five thermal waves gener-
ated  at the five symmetric peripheral positions.  Tests of a prototype
unit  indicated that this configuration does not provide signals which
have  adequate precision to measure fluid flow with the desired  accuracy.
The dissipation of heat was determined  to be quite large, as was  the
ratio of the average stream velocity to  the apparent boundary layer
velocity.

The stage measuring system utilizes an  electronic liquid level  gage
which consists of  two  solid rods  formed  to fit the inside curvature of
the sewer pipe.  One rod is- driven by an electrical  signal, and the
other rod acts as  a variable  tap  whose  output varies as  a function of
                                    388

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water  level.   The instrument is capable of accuracies better than 1 per-
cent of  full  scale.   This is a commercially available system manufac-
tured  by Marsh and McBirney, Inc.

WASTEWATER FLOW MEASUREMENT IN SEWERS USING ULTRASOUND

Reference  (84)  describes the use of newly developed ultrasonic velocity
measurement equipment in conjunction with ultrasonic level measurement
equipment  for the measurement of sewage flow.

"Each  ofi two  exl&ting (combined]  sewets in the. MUuxiukee (Wisconsin)
Sewage. System,  one. 12-1/2 fit and the, other 5 fat Jin diameter, were
.#106 equipped initiaJUly.   Subsequent discovety oft an excessive amount
ofi entrained  air at  the. 12-1/2 fit diameter. A ewe*. site necessitated the.
transfierral^ofi  that  equipment to a mono, favorable location upstream In
a 12-fioot  diameter sewer.   'Performance o^ the. ultrasonic metens was
compared with other  metering de.vlc.eA at each ofi the. location*.  Rela-
tionships  between average volume filow,  wateA level, and average. veJtoc.-
£ty along  Aele.cted horizontal chondx, ofi the. AeweA. C/WAA Ae.ctiom> W&UL
deteJtmtne.d.   A  continuous  fLe.c.ofui o£ filow wa& di&played and x.e.c.oftd.e.d.
The. unit tn& tolled in the. 5-fioot dlameteA. A ewe*, hat, operated fan. a pe-
fiiod ofi  18 month*  without fiailuA.e. and ha& tuLqyJbuLd. only routine, maln-
te.nance..   SimWvtly  the. x.elocate.d unit tm>talle.d at the. 12-fioot diame.-
teJt AeweA  Atte.  ha& opeAate.d without fiailu/te. A-ince. it* installation.   Wo
deterioration oft the. ul&ia&onic. t^an&duceA probes ha& been detected to
date -indicating tkeAjt suitability fiox. use -in the sewefi environment.   The
electronics ofi  the ultrasonic, velocity metering, unit were modifited to
Include peak  protection,  automatic gain control,  and automatic, trigger
control to minimize  the ejects  ofi variations In the. solids loading."

Further observations concerning use of the ultrasonic equipment are as
follows:

     a.  Similar equipment  has been used in Japan to successfully
         measure full pipe  flow of return sludge with high solids
         loadings.   For practical line diameters, say from 0.2 to
         5m (0.5 to  16 ft),  no operational limitations due to sus-
         pended solids would be expected.

     b.  Entrained air bubbles were found to cause operational
         problems  because of dissipation of the ultrasonic pulse
         due  to scattering  by the bubbles.   Therefore,  it  is
         recommended  that measurement  sites be selected which are
         reasonably  free of severe upstream agitation which would
         cause  air entrainment.

     c.  Difficulties  with  level  gage performance resulted from
         standing  ripples in the  sewage surface which interfered
         with echo returns.   This  was  alleviated  by moving the
         level  sensor  a few feet  to a point where the sewage sur-
         face was more still.
                                   389

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     d.  Comparative figures  of  flow as measured by the ultrasonic
         equipment with  those measured by other metering devices
         are not given for  the demonstration sites described.

     e.  Total system cost  for each site was about $15,000.  Fu-
         ture simplifications of the ultrasonic circuitry made
         possible through more extensive use of integrated cir-
         cuits have the  promise  of reducing this system cost by
         a factor of two or three.

BIOLOGICAL TREATMENT OF  COMBINED SEWER OVERFLOW AT KENOSHA, WISCONSIN

Reference (85) describes the  design, construction, operation and two
year evaluation of a biological  process used for the treatment of po-
tential combined sewer overflow.  A 76 MLD (20 MGD) modified contact
stabilization process plant was  constructed on the grounds of the city's
existing 87 MLD (23 MGD) conventional activated sludge plant at a total
cost of 1.1 million dollars.

"Vu/ung 1970 while. design and con&tnuction o& the. demonstration sys-
tem fiacilitieA WA occuwing, a  pJiogiam to determine. the, quality o&
the. combined &&aesi OUCA^OMW  in  K.e.no&ha wa& carwied out.  ThL& include.d
meaAusieme.nt o{ nainfiall, combined &eweti oveJifilow quantity and quality,
and influent quatlty to  the, WPCP  (wateA pollution control plant) dating
Flow measurement  equipment was installed in the outfall lines of three
overflows, known  as  the 57th Street, 59th Street, and 67th Street over-
flows.  Depth  recorders installed were operated on a differential pres-
sure basis.

"Inert nitrogen ga&  wa& inttLodu.c.e.d into tubing which ftan betu)e.e.n the.
Aeco/tdeA. and the.  bottom o& the. outfall &eif)eJt.  M the, &toM (ke.ad] in
the. &eM&L i.ncJte.a&e.d, ptwpofitianat to the, depth. o& £Ccw>, causing
the. pfLeA&u/Le. within  the. tube, to in&ieaAe..  Thi& incJieaAe. *.n pJieAAufie.
wat> c.onveJtted  to  depth fiejading& and fte.c,onded on a cinculat chant.  The.
chant wa& dividzd into 24 e.qu.at &e.ction& and dfiive.n by an 8 day clock."

Depth-discharge relationships were developed for the three overflow
lines by means of dye tests.  However, no details of the test proce-
dures were  given.

As a result of an unsuccessful attempt to correlate rainfall volumes
with overflow volumes, it was disclosed that the overflow measuring
devices were of questionable accuracy.  In some cases, the volume of
overflow measured exceeded the volume of rainfall over the combined
sewer area.   Apparently, the depth-discharge relationships were not
accurate and so the overflow data were not used.
                                    390

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 Measuring sites  at  the 57th Street  and 59th Street  overflows  were aban-
 doned in 1972.   The depth recorder  at  the 67th Street  site was moved
 upstream above the  weir diverting flow to the interceptor sewer.   The
 end  of the bubble tube was placed just upstream from the overflow
 mechanism, and a formula for broad-crested weirs was used to  convert
 level over the weir into flow  rates and volumes.  Flows  computed  in
 this manner were used  to estimate the  total volume  of  overflow to the
 demonstration treatment plant.

 FLOW AUGMENTING  EFFECTS OF ADDITIVES ON OPEN CHANNEL FLOWS

 Reference (86) describes some  laboratory experiments conducted to study
 the  effects of polymer additives  on open channel flows.   Two  sheet
 steel channels 18m  (60 ft)  long and painted initially with epoxy  paint
 (n=0.009)  and later with a sand and paint mixture (n=0.013) were  used
 in the tests.  One  channel was rectangular with a bottom width of 15 cm
 (6 in.)  and a side  length of 15.2 cm (6 in.)  while  the other was  trape-
 zoidal with a bottom width of  12.7  cm  (5 in.),  a 60° interior  angle,
 and  a side length of 15.2 cm (6 in.).   Slopes could be adjusted to 0,
 1, 2,  3,  and 4%.

 A series  of tests was  conducted to  determine  the effects  of a  polymer
 additive  on four  types  of flow measurement devices.  A  Parshall  flume,
 90°  V-notch weir, and  suppressed rectangular  weir were adapted to  the
 smooth-wall rectangular  channel and tested at a 1%  slope, while a
 Leopold-Lagco flume and  a 90° V-notch weir were tested in the  smooth-
 wall trapezoidal  channel  at a 2% slope.   No sizes are given for any  of
 the  flow measurement devices, nor can they be estimated from a photo-
 graph in  the report except to note  that  the crest height  of the rec-
 rangular weir is low (perhaps 20% or less  of  the channel  depth) as is
 that  of  the V-notch weir  for use in the  trapezoidal channel.   Con-
 versely, the V-notch in  the weir used in the  rectangular  channel appears
 to "run out" at the top  of the channel.

 The  general procedure followed was  to calibrate each device in  place
 using  tap water, and then to inject the polymer to yield a predeter-
mined  concentration and develop a new calibration curve.  Head was
measured using a pointer  gage ."usually at  the inlet to the device".
A stop watch, 19£ (5 gal) bucket,  and scale were used to determine
 flow rates under 570 t/m  (150 gpm)  (where most of the data were taken),
while an orifice meter was used for higher flow rates.

 Calibration of all  devices was affected by the addition of polymers.
The Parshall flume was least affected,  while  the V-notch weir suffered
a greater calibration curve shift (e.g., discharge could be understated
by over 50% of all but the lower flows).  The Leopold-Lagco flume and
the rectangular weir ceased to be effected as flow measurement devices
above a transition  flow rate.  The data are inconclusive, but indicate
that polymer additives can affect primary flow measuring devices and
point out the need for careful research in this area.
                                   391

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SURGE FACILITY FOR WET AND DRY WEATHER FLOW CONTROL
Reference (87) represents the culmination of a 3-year demonstration
project which encompassed the design, construction, operation, testing
and evaluation of a surge facility designed to provide flow equaliza-
tion and some degree of treatment to all storm flows and to provide
rate control of all wet weather and dry weather wastewater flows to
interceptor sewers.

The principal elements of the facility are a sedimentation-equalization
basin, a clarifier, a storage pond, a chlorine contact basin, and a
sludge digester.  Flow and hydraulic measurements include:  (a) influ-
ent to the sedimentation-equalization basin; (b) underflow from the
sedimentation-equalization basin to the clarifier and the storage pond;
(c) overflow from the sedimentation-equalization basin directly to the
storage pond; (d) water surface elevation of the sedimentation-
equalization basin; and (e) effluent to the chlorine contact basin and
the receiving stream.

The influent metering structure is a Parshall flume with a 0.30m  (1  ft)
throat width having a maximum capacity of approximately 30 MLD  (8 MGD) .
The influent flow transmitter to the control building can be used to
control a flow proportional sampler of the influent.

Underflow from the sedimentation-equalization basin is measured with a
15*2 cm (6 in.) magnetic flowmeter.  The underflow can be set at any
desired rate up to 8.7 MLD  (2.3 MGD).

Overflows from the basin are measured by four sharp-crested rectangular
weirs, totaling 2.54m  (100  in.).  Head on the weirs, and  the water sur-
face fluctuations in the sedimentation-equalization basin, are monitored
with a Stevens Type F water-stage recorder.  Time  gears were  selected to
give an 8-day chart, and stage  gears were selected to give an indication
of 0.06m/cm  (0.5 ft/in.) of chart or 0.012m/cm  (0.1 ft/in.) of  chart,
depending on  the depth variation expected during any particular  testing
period.

Effluent  from the  facility  is measured with a combination of  a  15.2  cm
 (6 in.) Parshall flume and  a 137 cm (54  in.) sharp-crested rectangular
weir.  The two  flow measuring devices are set to give a  combined capac-
ity of 22.7 MLD (6 MGD).  The effluent  flow transmitter  can be  used  to
control a flow  proportional sampler of  the  effluent.

No discussion of problems with  flow measurement equipment is  given in
the report.   Flow  data presented  in the report  appear  to be  complete
and accurate.   "O&tfe. the, 4M.iZu.un£ and andeA^loia meie^ed and the. wateM.
        monAtoft.e.d  c.ont*niwu&ly , -it WOA  JieZativzly e&5£/ to produce, a
                   nat
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A PORTABLE DEVICE  FOR MEASURING WASTEWATER FLOW IN SEWERS

Reference  (88) is  a final report of  a program to develop a portable
device capable of  measuring wastewater flow in sewers.   The work con-
sisted of:  an investigation of the  theoretical approach to be used;
laboratory investigations and experiments  to develop  design criteria;
design and fabrication of two prototype units; 'and field testing and'
evaluation of these units .

Methods investigated  for determination of  velocity in the sewer,  prior
to selection of the heat pulse method  for  development, are as  follows:

     a.  Capacitance  - Air Bubble Method

         This method  depends upon the  electrical  capacitance of
         the wastewater flow cross-section and  the  effect  on this
         capacitance  of the displacement of  air bubble tracers as
         they rise and are swept downstream past  a  capacitor
         plate.   This approach failed  due  to "background noise"
         and,  at low velocities, due to too rapid rise of bubbles
         in the  flowing water.

     b.   Inductive Method
                   a dsu-ve. coll zxA.vun.aJi to the. pipe. to cneate. an
         audio fyie.qu.ency magnetic. fileld.  The. magnetic {leld, Jin
         tuxn,  Induce* an. eddy cjjjuuunt in any neanby conductor,
         Auch 06 the. watex. In the. pipe..  Thl& eddy cuAA.e.nt can be.
         detected by Aentltlve. pickup collb located neMi the. pipe.
         wwesit.   Ifi the. wateA li> moving,  the. signal dete.cte.d wWL
         be. out oi phate. with the. &&LongesL ttgnal x.eAu&Ung faom
         d, the. amount
         oi tki&  pha&'e. Ahifit being cowie&ated mJth elective
         velocity."

         Failure of this method was attributed largely to the ex-
         treme  smallness of the signal to  be detected.

    c.   Electromagnetic Flowmeter

         This included the rather commonly used electromagnetic
         flowmeter approach for measurement in a full pipe.   How-
         ever,  it was  decided  that bulkiness of the equipment
         precluded its use for a portable,  easily installed
         instrument.

    d.   Electric Current  Method

        A voltage was applied across  a dynamic test  section, be-
         tween  two electrodes  in direct  contact with  the water.   A
                                 393

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         change in d-c voltage was observed as velocity changed.
         An increase in current was observed as velocity de-
         creased, with the filled cross-section remaining the
         same.  Problems encountered were random changes due to
         d-c signal "drift", and plating by the direct current on
         the exposed electrodes.    .

The method finally selected for more detailed investigation involved
the timing of a heat pulse as it traveled down the pipe.  Thermocouples
were used to sense the travel of heat induced by the injection of steam
into the flowing water.  Measurement of the cross-sectional area of
flow was done by the use of capacitor plates to sense the change in wa-
ter level in the sewer pipe.

"Jwo phototype, gage* WVUL ^ab^Ldat&d.  Tke. ov&tatt ac.c.unac.y oi tke. i, at bz&t, ±75 peAc.e.nt."

JOINT CONSTRUCTION SEDIMENT CONTROL PROJECT

Reference  (89) describes a demonstration project which consists of:
(a) the implementation, demonstration, and evaluation of erosion con-
trol practices;  (b) the construction, operation, and demonstration of
the use of a stormwater retention pond for the control of stormwater
pollution; and  (c) the construction, operation, and maintenance of
methods for handling, drying, conditioning, and disposing of  sediment.
As part of the project, a gaging and sampling program was conducted to
determine  the effects of urbanization on storm runoff and water quality
of natural areas.

Four automatic flow gaging  and  water sampling stations were  installed
on small streams of the study area.  Two of the stations were installed
adjacent to each other on streams just upstream from their junction.
One of these  streams drains an  experimental watershed and the other
drains an  adjacent reference  watershed.  Two other  gaging and sampling
stations were established immediately upstream and  immediately down-
stream from a 1.6 Hectare  (4  acre)  pond.

At three of the gaging  sites, precalibrated, broad-crested,  V-notch
weirs developed and  tested  by the U.S. Department of Agriculture were
installed.. At  two sites,  the concrete weir  caps have  2:1 side slopes;
at the third  site,  side slopes  of the weir cap  are  at  3:1.   At the
gaging site downstream from the four-acre  pond,  a sharp-crested,  com-
pound, 90°, V-notch  and rectangular weir was installed.

A Stevens  Duplex Water-Level Recorder  Type 2A35 was used to simultane-
ously  record  water  levels  at the two adjacent stream sites.   A Stevens
Type A35 water level recorder was used upstream from the pond, and a
Belfort  liquid level recorder was used at the downstream site.
                                   394

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  A Gurley pygmy current meter was available to perform additional stream
  gaging, but was used primarily to check the calibration of the perma-
  nently installed weirs.                                        v

  The weirs and level recording devices used are said to "have proven to
  be accurate, reliable, and easy to maintain".  However, it was found
  necessary to clean out sediment above the three U.S.D^A. weirs "—aAtefi.
  (MchAtcwn and AomeMme* undvi ba&e. {tow c.ondJiAJLon& to maintain the.
  caO,bfUVUan and ac.CMM.zy ofi th
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Because of the extended period of high river  stage,  flow measurements
during wet weather were generally not  obtained in the sewers or over-
flow points.  During this period, most of  the flow measuring sites were
either submerged or at least  intermittently affected by high water.
Overflows at one point were estimated  by use  of the  Manning formula,
and at another point by use of a current meter.

Stormwater runoff was measured at four gaging sites  on storm sewers.
At three sites, flow was measured by means of weirs  and bubbler re-
corders.  During periods of high river stage, one of these sites was
submerged or affected by backwater,  when no record was obtained.  Run-
off at the fourth site was determined  from a  stage-discharge relation-
ship established by current meter measurements.  A concrete sewer line
crossing the channel provided a  permanent  type control.  The rating
curve was extended an undisclosed amount above the highest current me-
ter measurement.

COMPUTER MANAGEMENT OF A COMBINED SEWER SYSTEM

Reference  (91) describes a computer-controlled "total systems manage-
ment" complex, which affects  much of the combined sewer system of
Seattle, Washington.  Computer-augmented treatment .and disposal  (CATAD)
takes advantage  of storage in the sewers to limit overflows, and se-
lects overflow points based  on water quality data.
          ...... .....    '            '       '
Development of the control system included the installation of 36  re-
mote sensor stations  and  the construction of 15 gate-driven regulator
stations.  Work  continues  on a fully automatic optimizing model  to
program decisions so  the  system can maintain an 80% overflow reduction.

"Wat&i le.\>eJL&  at many location*  ate. pft.oba.bly the. mo&t important tingle.
category  o£ information r.e^uir.ed to calculate,  filom and trigger.  certain
type* 0|J  alarm*.  fty incorporating  Manning'* equation*, variou*  otifiice.
and vioir.  formulae. and pump e.Uiciency curve*, -it i& po**ible. to  calcu-
late.  ilow at almo&t any location In. the. *y*tem.  The. compute*,  check*
wtvt eZevation* wutti n.e.ivience. to ovesifilou} weir* to generate.  pre.-
alatm&  be.6ofi.e- oveA^low* take, place, and/oft, actual alarm* a£teA  the. over.-
 Aeow  had  begun.   Monitoring ,  control and modeling a& the.  entitle. &y£>tw
depend upon &lou) information, faon many location*,  &ome. oi  which cannot
be. obtaine.d ^m wateSi level me.aAufi.eme.nt!> alone..  In the.  CATAt? &y&tw,
      additional on-line. £low meoAuAing te.chniqueA  one. employed'.
1.   flow meja&uAing
                               ate. in&taHe.d at vaniouA location*.
      2.  A catlbstjated pfiopetleA. type.  filoimzteA. it>  monitofied at the.
               Point treatment plant &ite..
      3.  lFon.ce. main. pieAAusie. calibration method*  ate. u&ed at pump
          AtationA whesie. theJie. ii> Au^icient friction head lo£>& to
          calibrate, the. fiotce. main at vaniou& &low range*."
                                    396

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 In addition, more than 100 Palmer-Bowlus flumes are installed in man-
 hole locations.   A computer program has_been applied for rating these
 measuring flumes, using data including sewer diameter,  shelf height,
 flume side slopes, and elevation of vertical side slopes.

 Level sensors used in the system are generally pneumatic bubblers with
 back pressure read by a differential pressure transmitter.   The accu-
 racy of measurements was checked by direct level measurements to bring
 instrument calibration of the various stations into agreement with the
 system datum.  It was determined that the overall accuracy  probably ap-
 proaches about 2% of the full scale measurement.

 Project experience demonstrated  that manufacturer's pump unit perform-
 ance curves may  be used to calculate reliable flows provided that crit-
 ical analog sensors,  particularly pump speed sensors, are reliable;

 Because flows  calculated using performance curves had been  considered
 dubious,  force main pressure sensors were installed at many pump  sta-
 tions to provide alternative means  of calculating station discharge.
 As  a result of checking the pressure gages using  the salt velocity
 method,  it was found  that flows  thus calculated are not  entirely'reli-
 able due to rapid fluctuation of analog pressure  values.

 Deficiencies in  the flow calculation procedures for regulator  stations
 were revealed.   No allowance had been made for the  effect of intercep-
 tor backwater  affecting the tailwater at  a regulator gate and no  tran-
 sition had been  provided between fully-submerged  and free .discharge
 conditions.  A backwater allowance was  added, and a method  of  calculat-
 ing the  degree of  gate  submergence was  developed.

 CHARACTERIZATION AND TREATMENT OF URBAN LAND RUNOFF

 Reference  (92) describes  a  project to characterize  the runoff from a
 4.3 sq km  (1.67  sq mi) urban watershed  in Durham, North Carolina with
 respect to  annual pollutant  yield.  The U.S. Geological Survey operates
 a continuous stage recorder  and  two digital punch tape precipitation
 recorders within the basin.   Stream-flow control  is provided by a
 shallow V-notch weir located  on Third .Fork Creek  some 21m (70 ft) down-
 stream from a bridge culvert  and 11.3 km  (7 mi) upstream from the mouth
 of  Third Fork Creek.  Water  quality samples were  taken from the center
 of  the stream approximately  1.5m  (5 ft) below the weir.   Thus, rainfall,
 runoff, and water quality data were gathered for  the basin and analyzed.
 The USEPA Storm Water Management Model  (SWMM) was also evaluated with
 respect to actual conditions as measured in the field and "was judged
 to  predict peak hydrograph flows and total hydrograph volumes with rea-
 sonable accuracy; however it was not judged effective for predicting
pollutant concentrations".

 In  order to assess the impact of varying types of land use. within the
basin on urban runoff quality, 5 storms were manually sampled at sub-
basin discharge locations.  A control section, usually a pipe or box
                                  397

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culvert, was utilized with Manning's equation to arrive at stage-
discharge relationships for each basin sampled.  The stage was manually
read when a sample was taken.  No accuracy estimates are available.

OTHER USEPA PROJECTS

Among USEPA projects for which final reports are not available is a
project (EPA S-802400) to demonstrate disinfection and flash treatment
of combined sewer overflows at Syracuse, New York.  Disinfection is ap-
plied for one minute after solids removal by high rate screening.  Flow
of combined sewage is measured from three pumping stations to installa-
tions of fine mesh and micro screens.  Also, flow in solids return
lines from the screens is measured and used to control backwash of the
screens.  Flow from the three pumping stations is measured by Brooks
electromagnetic flowmeters.  Solids return from the screens is measured
with a weir and a Badger Meter, Inc. float level indicator.  Problems
were experienced in printed circuits of the signal converters used with
the Brooks electromagnetic flowmeters.  Initially, other problems
necessitated that adjustments be made by Brooks' representatives.

A USEPA grant project  (EPA Y-005141) with the Monroe County Pure Waters
Authority is to develop a master plan for treatment, conveyance, or
holding alternatives to effectively handle the combined sewer overflows
from the Rochester, New York, sewer system.  Flow quantity and quality
data collected for the project are to be used in calibrating the USEPA
Stormwater Management Model.  The master plan is to be so developed to
provide guidelines for use in preparing such plans for other cities.
Measurements of thirteen combined sewer overflows, and at four loca-
tions in interceptor sewers, are being made.  At five of these loca-
tions, Badger Meter, Inc. ultrasonic flowmeters are used in conjunction
with Badger ultrasonic .water surface level indicators.  At eleven loca-
tions, Badger ultrasonic level indicators only are used to record head
over weirs or to provide data for use with the Manning formula.  A
Fischer-Porter bubbler gage above a combination weir-orifice is used
for flow measurement at one site.  All data are transmitted to a cen-
tral computer.  Redesign of the ultrasonic head probes was found neces-
sary due to echoing in the sewers, but they are now reported to be
operating satisfactorily.  Problems of interfacing with the computer
were experienced, but very good operation has been obtained after six
to eight months' experience.

A project  (EPA No. 11024 FIU) was for the design, fabrication, and
testing of a prototype 30.5 cm  (12 in.) vibratory sewer flowmeter.  The
flowmeter to be developed was to operate on the principle that the re-
action of flowing material to a mechanical vibration applied to  the
stream boundary in a direction transverse to the direction of flow is a
direct measure of mass flow rate.  The essential elements are an actu-
ator to impart a vibratory force or motion to  the flowing material and
a  sensor to measure the reaction.  This type of device has been  used
                                   398

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 successfully for measuring very small flows,  but the mechanical prob-
 lems with equipment for use in a sewer were not successfully solved
 with the time and funds available.           '.:.,    .                 .

 A project (Contract No. EPA 68-03-0341) with  Gushing Engineering is for
 the "Development of an Electromagnetic Flowmeter for Combined Sewers",
 which may result in a device capable of measuring flow under -open-
 channel conditions as well as in a  full, pressurized pipe  is in prog-
 ress.   The open channel electromagnetic'flowmeter will have a primary
 unit or transducer (i.e.,  the portion through which  the fluid flows)
 that is not considered to  be appreciably more-• complicated  than the  con-
 ventional instrument;  however,  it does require  more  sophistication  in
 its secondary unit (i.e.,  in its signal conditioning unit).   The pri-
 mary unit is very similar  to standard electromagnetic flowmeters ex-
 cept that in this case a manifold of detection  electrodes  (as opposed
 to a single pair)  are employed  so that measurement can be  made through-
 out the varying depth of the liquid.   The outputs  of the detection
 electrodes are fed into an adder network which  totals the  voltage  ;  ;
 sensed in accordance with  height of  flow.                           ,; '

 The EPA has contracted (Contract No.  68-03^2121) with Grumman Ecosystems
 Corporation for the development of a new,non-intrusive, low cost,  pas-
 sive measurement system capable of monitoring flow in storm,  combined,
 and sanitary sewers.   The  system's concept  involves  a proprietary tech-
 nique  of  utilizing the sound emission resulting  from the interaction  of
 fluid  flow with a discontinuity of a solid  surface.   In the  application
 to sewer  flow,  a discontinuity  is any inherent  change in the sewer
 cross-section,  slope,  or direction that  can significantly  affect  the
 flow area or direction.  Laboratory  investigations directed  to optimize
 system design details  for  sewer installations, and analyses which will
 relate  theory and  test  data  to  measurement  system design objectives and
 applications  are  currently underway.   By proper signal  processing,  the
 acoustic  emission  flowmeter  can be made  to  differentiate between sound
 that is indicative  of and  generated by the  quantity  of  flow  and noise
 caused by noncorrelatable  secondary flow processes and  general back-
 ground noise.   Several  factors may affect sound production and transmis-
 sion in wastes  such as  a suspension of bubbles,  temperature gradients
 and stratification, etc.   These areas must be investigated and either
 avoided or  compensated  for by selection of sound pickup locations.

PROJECTS  BY OTHER FEDERAL AGENCIES

Federal agencies which have been active in development of improved flow
measurmenet equipment and methods, with a brief description of their
work, are given below.  Other Federal agencies have carried on similar
useful projects in past years, but have been omitted where -information
on possible recent work was not available.  The information presented
here was  obtained either by telephone or personal interview. ;
                                  399

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Agricultural Research Service

Work on improved designs of trapezoidal-type measuring flumes to over-
come sediment problems is being conducted in Phoenix, Arizona.

Bureau of Reclamation

Radioisotope Flow Measurement - Equipment and methods for measuring
flows in canals, pipelines, and turbines-with radioisotope tracers have
been developed by the Bureau during the past ten years.  Public resist-
ance to injection of radioisotopes into water supplies has minimized
their use.

Ultrasonic Flowmeter - Ultrasonic flowmeter equipment furnished by^the
Badger Meter Company was tested in a 61 cm (24 in.) diameter pipeline
and in a 76 cm  (30 in.) wide channel.  A measurement accuracy of ±2%
was obtained in the pipeline.  A significant conclusion was that the
flowmeter transducers should be installed in direct contact with the
water rather than on the outside of the pipe.

Rotameter-tvpe Flowmeter - Combined rotameter-type flowmeter and flow
controllers of  25.4, 30.5, and 35.6 cm  (10, 12, and 14 in.) sizes were
studied in the  laboratory.  These devices totalize flow, indicate flow
rate, control flow to preset rates, and provide shutoff.  Further field
operation and experience is necessary to fully evaluate the devices.

The Bureau of Reclamation  conducts a continuing research program in
the fields of water  system automation and flow control.  Studies in the
use of electromagnetic  and ultrasonic methods of  flow control are in
progress.

Corps of  Engineers

Recently, Westinghouse  ultrasonic  flow  measurement equipment has been
 installed on the Columbia  River  to provide  improved  information on
 powerplant operation.   This work was performed by the personnel of  the
 Portland District in cooperation with the U.S. Geological  Survey.

 Satellite transmission of  data is  being investigated in the New England
 Division.   Telemark data transmission  systems are being discontinued
 and are being replaced by radio transmission.   It is expected  that data
 transmission in the future will be tied to  the National Oceanic and
 Atmospheric Administration System of Automation  of Field Operation and
 Services.

 Geological Survey

 The Water Resources Division of the Geological Survey maintains a con-
 tinuing program to improve water measurement devices and procedures.
                                   400

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 Recently, a flow measurement device for measurement of storm runoff in
 sewers has been developed, and a number of them are being installed in-
 several sewered catchment basins.  The device functions within the
 sewer under both open-channel and pressure flow conditions, and is said
 to cause only an insignificant amount of head loss.  Undfer open-channel
 conditions, the meter functions as a venturi flume.  Fpr pressure
 flows, the device operates like a modified venturi meter.  This flowme-
 ter is very similar to that developed by Dr.  Harry G. Wenzel of the
 University of Illinois.  A significant difference is that the upper po-
 sition of the pipe is unconstricted,  reducing discontinuity between the
 open-channel flow rating and the pressure flow rating.

 PROJECTS OUTSIDE THE UNITED STATES

 The reader is cautioned not to assume that all the flow measurement   •
 research today is being .conducted in  the United States.   Most industri-
 alxzed countries are active in this area,  and new or improved flow
 measuring devices and techniques  are  being reported by foreign investi-
 gators.   Coverage of all foreign  research simply was outside  the  scope
 of  the present effort,  but  would  be a fit  subject for a  future study.  '

 However, mention will be made  of  one  Canadian development recently re-
 ported by Marsalek  (93)  because of its promise for application at  sites
 troubled by surcharging.  It is essentially a flume-dilution combina-
 tion for sewer flow  measurement.  The  equipment  involved is all porta-
 ble and suitable for manhole operation.  At the  primary wastewater
 characterization site a  Palmer-Bowlus  type flume,  a water level re-
 corder  (a capacitance-type probe was used In  this  case), and an auto-
 matic discrete  sampler were installed.  At a manhole sufficiently
 upstream to assure that  complete mixing would occur a tracer supply and
metering feed pump were  installed.                                     •

Under ordinary  (open  channel) flow conditions only the equipment at the
primary site is in operation.  When the water level, as measured by the
capacitance probe, reached a pre-determined value indicating that sub-
mersion effects would be seriously degrading discharge values as meas-
ured by the flume, an alarm relay activates the tracer feeding pump at '.
the upstream site.  The chemical dilution technique is applied for the
 high flow  periods by analyzing the samples collected by the automatic
sampler to determine tracer concentrations.
                                  401

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                              SECTION IX
                   11            ,,„„,::",      '            '            &
               FUTURE AEEAS OF RESEARCH AND DEVELOPMENT


Although the general state of the art of flow measurement has come a
long way since the days of Sextus Julius Frontinus (e.g., we can accu-
rately measure cryogenic flows, liquid sodium flows, mixed gas and
vapor flows, etc.), the most common flow measurement devices and tech-
niques used in sanitary engineering are but modest improvements upon
nineteenth century (or earlier) developments.  This is not surprising
in view of the National priorities that have been given to space and
nuclear energy programs, and the concomitant application of resources
to the development of technologies directed toward, the solution of
problems in these areas.  As was pointed out earlier in this report, we
are now becoming more and more aware of the importance of accurate
sewer flow measurement and, in recent times, have begun to devote in-
creasing attention to it.  Storm and combined sewer flows, as noted,
are among the most difficult to measure well, and much remains to be
done before we can claim that the state of the art, as being practiced,
is equal to the task.

As a result of the activities conducted during the course of this
study, including the review of older research and development projects
as well as current and on-going,ones, it appears that  there are several
promising research areas that could produce  improvements within a
short-term time frame.  They have been divided into three categories:
general research, which is more basic or fundamental and applicable to
a number of different  classes of flowmeters; applications research,
which  deals with the engineering required  to adopt  already-developed
building blocks into flow measurement systems suitable for  the  storm
and  combined  sewer application; and  demonstration research, which  is
the  actual  field use and evaluation  of  existing  equipment that  either
has  not been  tried before  or  about which there is presently insuffi-
cient  information.

Several promising  activities  within  each area will  be  discussed.   No
attempt  to  be exhaustive  or  all-inclusive  has been  made.  Rather,  the
activities  suggested have been selected because  of  a  critical need, the
promise of  a  high probability of  positive  results,  and/or the immediacy
with which results could  be obtained.   The selections  are necessarily
 somewhat  subjective,  and doubtless  some readers  will  be concerned that
 one of their  "pet" areas  has not been included.   The  writers can only
 hope that any such criticism will be tempered by the realization that a
 complete coverage of all possible contributory research could more than
 double the size of this already somewhat lengthy report.

 Two general recommendations will be treated outside the just mentioned
 categories because they tend to overlap and are a bit more policy/
 priority than specific task oriented.  First,  there is a need for a
                                    402

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  facility where  controlled  flows of wastewater  can be maintained  so that
  varxous alternative devices and techniques can be tested  in a  side-by-
  side fashion.   It is imperative that this facility be capable  of opera-
  tion with actual sewage as well as water in view of possible
  interference effects to some flow measurement  equipment that might be
  caused by the former.  A facility was developed as a part of a USEPA
  funded study and evaluation of a periodic flushing system for  combined
  sewer cleansing by FMC Corporation.  It,has variable slope test  sewers
  of 30.5 and 45.7 cm (12 and 18 in.) diameters and can utilize  actual
  sewage.  It is recommended that this facility be evaluated for the pur-
  pose of side-by-side flow measurement device testing and so utilized if
  indicated.                                 ,

 The second general recommendation arises from the very nature of the
 storm and combined sewer application itself.   It is strongly recom-
 mended thatpriority be given to the development of portable flow meas-
 urement devices that could be used for overall survey work,  for
 gathering field data for use in the development of computer  stormwater
 management models,  for conducting infiltration/inflow studies,  and the
 like.   The importance of a portable flowmeter for each of  the cited
 uses is well known and will not be belabored  here.   The problem is  that
 the need is still largely un-met.   Of  the  following  research recommen-
 dations,  it is  recommended that those  activities  that will be contrib-
 utory, to the development of portable devices  be undertaken first.

 GENERAL  RESEARCH

 Much remains  to  be learned  about -the physics of complex flows such as
 stormwater  or combined  sewage.   They are multi-phase mixtures contain-
 ing solids,  liquids, and gases  and are unstable, with constituents go-
 aag into and out of solution as  the flow progresses.  .When combined
 with the problems introduced by nonuniform, unsteady turbulent  flow
 the research possibilities  are mind-boggling.   Only three, which  the
 ^^elS  ^   are  °th °f immediate concern and  reasonable tractibility,
 will be discussed.

 Effects of Entrained Air and Solids

 Entrained air and solids in the flow can have an effect on several dif-
 ferent types of flow-measuring equipment.  One of the most recent and
 promising methods of flow measurement utilizes ultrasonic equipment
which is known to be adversely affected by these elements.   Experience
 to date has shown that the presence of heavily concentrated air bubbles
 in the flow interferes with operation of ultrasonic flowmetering equip-
ment.  This is true even when the bubbles are so small that they are
hardly, visible.   The only solution thus far proposed is to  install the
flowmeter where such bubbles do not form; that is, to avoid locations
                                  403

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below drops, chutes, and hydraulic machinery which cause air entrain-
ment in the flow.  A method for overcoming this restriction of meter
applicability is needed, and should be investigated further.

A similar interference by solids suspended in the flow has been noted.
Although methods for overcoming the effects of larger, more widely
spaced suspended solids have been developed, fine silts remain a prob-
lem.  Further study to better understand and overcome such effects on
ultrasonic velocity measuring devices is recommended.

Polymer Effects

The introduction of selected polymers to pipe flows has been demon-
strated to significantly increase the pipe carrying capacity.  Flow
increases of as much as 240% at a constant head have been achieved.
Field tests reported by The Western Company  (94) on a 61 cm (24 in.)
line demonstrated that surcharges of greater than 1.8m  (6 ft) could be
eliminated by polymer additives.  Similarly, the capacity of open chan-
nels has been increased through use of friction-reducing additives,
although to a lesser extent, as noted by Derick and Logie (86).

The addition of polymers to the flow can have a significant effect on
the calibration  of  certain types  of flow measuring equipment, as also
reported by Derick  and Logie  (86).  Although they only  tested flumes
and weirs,  effects  could be even  more pronounced in  those devices that
presuppose velocity distributions in the flow.  Ultrasonic  flowmeters
are a particular case in point.   For example, little  is known about  the
effect  of  changing  the viscosity  of the water on the character  of the
ultrasonic  pulse through the water, or about the reduction  of turbu-
lence  causing  a  change  in  velocity distribution in the  cross-section.
Because of  the potential for  increased use of polymers  for  flow control,
study  of their effects,  especially  on ultrasonic flow measurement
 equipment,  is  recommended.

Velocity Distribution

 Although a significant effort has been made to define the relationship
 between average velocity along a horizontal chord  or traverse,  eleva-
 tion of the chord or traverse, and the average velocity in the cross-
 section, much more work would be helpful in reducing the cost of flow
 measurements.   Theoretical computations and laboratory and field obser-
 vations have been made in the past,  but a consolidation of known infor-
 mation, reinforced with selected additional data,  would be quite useful,
 since many of the flow measuring devices infer average velocity from
 point or chordal measurements.  This is particularly true with respect
 to ultrasonic flow measurements, where the average velocity along a
 chord or traverse between two meter probes is measured.  Further knowl-
 edge of these relationships would also be useful with other flow meas-
 urement devices where flow is computed from the product of average
 velocity in the cross-section and the cross-sectional area.
                                    404

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  APPLICATIONS  RESEARCH                '

  The state  of  the art  and  technologies are now at  hand  to  allow the  de-
  velopment, based on already  established building  blocks,  of  improved
  flow measuring devices  for application to the storm and combined sewer
  problem.  A few  examples will be discussed.

  Automated Dye-Dilution  Devices

  As  discussed  in  Section VI,  dilution  techniques are very promising  for
  application to the measurement of storm or combined sewer flows, espe-
  cially in view of the new fluorescent  dyes now available.  Suitable
  ifavS?Lr l^ controlled-rate °r ^ug  injection of dye solutions
  is  available.  Automatic sampling equipment to allow reliable gathering
  of  representative samples and fluorometers for automatically measurin-
  dye concentrations are also available.  There has even been work done°
  on laser stimulation of fluorescence which could allow remote observa-
  tion _ of dye concentrations without direct contact with the flow.  Pres-
  ent integrated circuit technology would allow automatic conversion of
 dye concentrations to flow rates,  in digital form, for indicating and
 recording and transmitting to central locations.   It is even possible
 to develop a portable, battery-powered version that could be used for
 field calibration of existing flow measurement devices.  It is recom-
 mended that a project  to integrate these  building blocks  into an auto-
 matic flow measurement device be established,  with emphasis on
 portability.

 Portable  Ultrasonic  Devices

 Sufficient  field  experience is now  available to demonstrate the  utility
 of ultrasonic  equipment  for the measurement of sewage flow,  including
 stormwater  and combined  sewage.  Development of portable equipment could
 expand  the usefulness"of this kind  of  flow measurement  device to meas-
 urements  of the miscellaneous type,  such as in infiltration studies, to
 check the effluent from  industrial plants, and for many other purposes.

 Basically, ultrasonic-flow measurement  equipment is adaptable to com-
 pact packaging, as no large,  heavy parts are required,  even-for measure-
 ments of  large flows.  Three  separate packages might be developed -  a
 level gage, several sets of meter probes,  and  associated electronic
 instrumentation.  Provision should be made for installing the probes
 either inside or  outside of closed conduits.  Again, the fundamental
 building blocks are at hand, and it is  recommended that such a proiect
 be initiated as soon as possible.

 New Flumes

As noted in Section VI, there has been extensive research work performed
on a variety of new flume configurations,  with resulting designs that
offer wider ranges, greater self-scouring  charaeteristics,  better
                                   405

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submerged performance capabilities, etc., as compared to the more tra-
ditional designs, especially the Parshall flume.  It is recommended
that a project be established to consolidate the existing information
on these efforts and, based upon this, to develop a flume possessing
the most advantageous attributes in light of present day technologies
and the storm and combined sewer application.  For example, it mxght
happen that a trapezoidal cutthroat 'flume with an automatic, electronic
dual head comparison (Hb/Ha) and critical/submerged/pressurized flow
algorithm shift integrated circuit card would offer great promise.
Such a design is totally within the present state of the.art and could
be effected at a reasonable cost.
                                                  /
Ultrasonic Level Gages

As secondary elements in flow measurement devices, ultrasonic level
gages show considerable promise-for the  storm and combined  sewer appli-
cation.  They obviate the self-cleaning  requirements of  many secondary
elements, offering  the advantage of no requirement for contact with  the
flow stream whatsoever.  Their use has been fraught with difficulty,
however,  especially in settings such  as  a manhole application.  The
problems, from discussions with various  field and applications engi-
neers, would appear to stem mostly from  spurious or  false  signal  returns
due to echoing from the  installation  structure.  The problem has  been
encountered in many applications,  e.g.,  the Rochester  project, and has
been independently  solved  (or  apparently so) almost  as many times.   *or
example,  the USEPA  National Field  Investigation Center,  Cincinnati,  has
experienced such problems with different makes  of equipment and  has  de-
veloped  an  inexpensive modification  that apparently corrects the prob-
 lem.   It is recommended  that a project to review the history of  such
 experiences,  including problem and solution descriptions,  be prepared
 and procedures developed for the use of ultrasonic level gages in such
 applications.

 DEMONSTRATION RESEARCH

 There are several flow measuring devices, either presently available or
 virtually ready to be introduced, that offer considerable promise in
 the storm and combined sewer application.  However, information about
 their use in such a setting is lacking, but could be gained from test-
 ing in a suitable facility as discussed earlier or from other field use
 such as a-demonstration as an adjunct to an on-going project; thus,
 definite recommendations as to their suitability or fitness as storm or
 combined sewer flow measurement devices can be made.  Some of these
 Will be briefly discussed.

 Venturi Meter/Flume

 These flow measuring devices  are  designed  to operate under both  open-
 channel  flow and full-conduit  flow under pressure.  Under  open-channel
                                    406

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                         aCt aS suPercritical flumes, but when completely
         and under pressure, they behave more like modified venturi me-
  ters.   For open-channel flow, only the depth at a single (usually up-
  stream) measuring section is required.  When the pipe is flowing full,
  and is under pressure,  the flow is a function of the difference in the
  upstream head and the head at,  say, the meter throat or an exit head;
  Two such devices have been recently developed - one by Dr.  Harry G

  oHhi'u I'  f f^ UVf S±ty °f Illin°iS»  'and °- ^George
  oi  the U.S.  Geological  Survey.
   ffiM  (i8 Jn'} diameter  test meter  designed by Dr. Wenzel has been
 sufficiently laboratory tested, but has  not undergone  field  experience
 to evaluate its self-cleaning characteristics and its  hydraulS per?orm-

 on a'61 L^rrr^ '""V PrOtOtype meter of larger' elze, at least
 In VfS  ?J    n° diameter  llne> be tested in an actual combined sewer
 in line with an accurately calibrated meter of another type.

 Several similar flumes designed by George F. Smoot for the U.S. Geolog-
 JSJ  r^7      b!en installed in storm or combined sewers.  However!
 there has not yet been sufficient field experience to allow adequate
 %S?frT,   I  ^ ^It: ±S recommended that a flume of this design be
 installed (preferably) in line with the meter designed by Dr. WeSel
 a                 Calibrated meter of Bother type for further
 Combination Thermal Flowmeter

 Two thermal flow tube meters are manufactured by the Thermal Instrument
 Company,  one for measurement of flow in pipes that are flowing full and
 another for flow measurement in partially filled pipe.   Although dis-
                                            °f theSe mSterS  - Ascribed
the.

                            <**.*»<**** otthe. tabz to compete and
                                 and cmblznt
                      .                         '          level.sensor
          on the outside of the unobstructed pipe, in addition to the
velocity measuring sensors.

Very little experience has been gained with this type of flowmeter in
measurement of sewage.  Meters are now in operation on 50.8 cm (20 in )
pipes carrying recycled pulp wastes.  There is said to be no upper limit
on the size or range of these meters.
                                  407

-------
Because of the obvious potential advantages of such nonobstructing me-
ters, it is recommended that they be evaluated in a line of moderate
size, but under conditions of both open-channel flow and full flow un-
der pressure.  The test meter would be placed in line with a flow meas-
uring device of another type with proven accuracy.

Self-Calibrating Acoustic Level Gage

The "Aquarius" acoustic level gage described in Section VII offers
many apparent advantages over more traditional ultrasonic level gages
as a secondary element in a flow measurement system.  These include:
complete independence from all environmental effects; almost an order
of magnitude greater accuracy than presently available; a low produc-
tion cost; portability, which includes  the promise  of outstanding bat-
tery life  (up to one year); and immediate computer  compatibility, owing
to its  advanced, all-digital electronic design.   At this time, however,
the device is so new that virtually no  data  (outside the laboratory)
are available to substantiate these promises  in a field setting.  It  is
recommended  that one of  these devices be procured and installed, at a
site with  a  suitable primary device, alongside a  proven head sensor in
order  to demonstrate its real capabilities  in a field setting.

High Range Open Flow Nozzle

 The H-series flumes (or open-channel flow nozzles), that were  developed
 by the U.S.  Department of Agriculture,  hold considerable promise as
 primary devices for successfully measuring storm and combined  sewer
 flows at many sites,  as discussed in Section VI.   In view of their low
 cost and very wide measurement range,  it is recommended that a project
 be initiated to:  (a)  gather available information on the various flumes
 of this type and other open flow nozzle designs;  (b) analyze this de-
 sign; and (c) fabricate and test such a primary device.
                                    408

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                              SECTION X

                             REFERENCES
  CITED REFERENCES

  1.   Jarvis,  C. S., "Flood Stage Records of the River Nile," ASCE
      Transactions,  V. 62 (1936), pp. 1012-1071.              	

  2.   Frontinus, Sextus J., The Two Books on the Water Supply of Rome.
      (written about A.D. 97,  but translated into English in. 189.9 by
      Clemens  Herschel), New England Water Works Association,  Boston,
      MA.   (1973).

  3.   Frazier,  Arthur H., "Dr.  Santorio's Water Current Meter, Circa
      1610»" Journal of the Hydraulics Division, ASCE Vol.  95, No.  HY 1
      (January 1969),  pp. 249-253.

  4.   Brator,  E. F.,  Department of  Civil Engineering,  University of
      Michigan,  Ann  Arbor,  MI,  private communication of unpublished
      manuscript (1971).

  5.   Lager, J.  A. and Smith, W.  G.,  "Urban Stormwater Management and
      Technology:  An Assessment,"  USEPA Office of Research and Devel-
      opment Contract  No.  68-03-0179  (draft of  report),  (December 1973).

  6.   United States  Congress, House,  Federal Water Pollution Control
      Act Amendments of 1972. Public  Law 92-500,  92nd  Congress,  First
      session. (1972).

  7.   American  Society of Mechanical  Engineers,  Fluid Meters - Their
      Theory and Application. Report  of  the ASME Research Committee  on
      Fluid Meters, Sixth Edition (1971), The American  Society of Me-
      chanical Engineers, New York, NY.

  8.   Replogle,  J. A.,  "Flow Meters for Water Resource Management,"
      Water Resources  Bulletin. May-June  1970, pp. 345-374.

  9.  McMahon,  J. P.,  "Flow of Fluids", Section 5-1-of Handbook of Applied
      Instrumentation. D. M. Considine, Editor-in-Chief, McGraw-Hill Book
      Co., New York,  N. Y.  (1964).

10.  United States Department of Interior, Bureau of Reclamation, Water
     Measurement Manual. Second Edition  (1967), Superintendent of Docu-
     ments, U.  S. Government Printing Office, Washington, D.  C.

11.  Leupold and Stevens, Inc., Water Resources Data Book. First Edition
      (1974), Leupold and Stevens7 Inc., P. 0. Box 688, Beaverton.
     OR. 97005.
                                   409

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12.  American Society of Testing Materials, 1973 Annual Book of ASTM
     Standards, Part 23 - Water; Atmospheric Analysis, American Society
     of Testing Materials, 1916 Rose St., Philadelphia, PA.  19103.

13.  Ball, H. E., "Flow Tubes and Non-standard Devices for Flow Meas-
     urement With Some Coefficient Considerations," in Proceedings of a
     Symposium on Flow Measurement in Closed Conduits held at the Na-
     tional Engineering Laboratory, Gt. Brit., Sept. 27-30, I960,
     Volume 2, Section D, Her Majesty's Stationary Office, Edinburgh
     (1962).

14.  Cortelyou, J. T., "Centrifugal Flow Measurement," Instruments and
     Control Systems, Vol. 33, No. 2 (February 1960) pp. 276-280.

15.  Taylor, D. C. and McPherson, M. B., "Elbow Meter Performance,"
     Journal American Water Works Association, Vol. 46, No. 11
     (November 1954), pp. 1087-1095.

16.  Replogle, J. A., Myers, L. E. and Brust, K. J.,  "Evaluation of Pipe
     Elbows as Flow Meters," Journal of the Irrigation and Drainage Di-
     vision, ASCE Vol. 92, No.  1R3  (September 1966),  pp. 17-34.

17.  Fleming, F. W. and Binder, R. C., "Study of Linear Resistance Flow
     Meters." Transactions ASME, Vol. 73  (1951), pp.  621-624.

18.  Greef, C. E. and Hackman,  J. R., "Capillary Flow Meters,"  ISA Jour-
     nal,  Vol. 12, No. 8  (August 1965), pp. 75-78.

19.  Souers, R.  C. and Binder,  R. C., "Study of Linear-Resistance  Meters
     for Liquid  Flow," Transactions ASME,  Vol.  74  (1952),  pp.  837-840.

20.  Kehat, E.,  "Constant Cross-Section, Variable  Area Flow Meter,"
     Chemical  Engineering Science,  Vol.  20, No.  5  (1965),  pp.  425-429.

21.  Gilmont,  R.  and Roccanova, B.  T.,  "Low-Flow Rotameter Coefficient,"
     Instruments and Control Systems, Vol. 39,  No. 3 (March  1966),
     pp. 89-90.

22.  Skogerboe,  G. V., Hyatt,  M. L.  and Austin,  L. H., "Design and Cali-
     bration of  Submerged Open Channel Flow Measurement  Structures -
     Part 4,  Weirs," Utah Water Research Laboratory, College of Engi-
     neering,  Utah State University,  Logan, UT,  Report WG 31-5, May 1967.

 23.  Engal,  F. V. A.  E.,  "Non-Uniform Flow of Water:  Problems and Phe-
     nomena in Open Channels With Side Contractions," The Engineer,
     Vol. 155 (1933),  (April 21),  pp.  392-394, (April 28), pp. 429-430,
      (May 5),  pp. 456-457.

 24.   Cone, V. M., "The Venturi Flume," J. Agricultural Research. Vol. IX,
      No. 4 (April 1917), pp. 115-123.
                                     410

-------
 25.  Parshall, R. L. and Rohner, C., "The ,Venturi Flume," Colorado
      Agricultural Experimental Station Bulletin No. 265 (1925).

 26.  Parshall, R. L., "The Improved Venturi Flume," ASCE Transactions.
      Vol. 89 (1926), pp. 841-851.                   	^~"	. _;,;•*

 27.  Palmer, H. K. and Bowlus, F. D., "Adaptation of Venturi Flumes to
      Flow Measurement in Conduits," ASCE Transactions. Vol. 101 (1936)
      pp. 1195-1216.                 ~~      ~~	,          >.-;   '

 28.  Kilpatrick,  F. A.,  "Use of Flumes in Measuring Discharges at Gaging
      Stations," Surface Water Techniques. Book 1 Chapter 16 (1965), U.S.
      Geological Survey,  United States Department of the Interior,  Wash-
      ington, D.C.
                                                   ....   •      * , "c ,'

 29.  Robinson,  A. R., "Parshall Measuring Flumes of Small  Sizes,  ;  '
       Colorado Agricultural and Mechanical College, Agricultural Experi-
      mental Station Bulletin No.  61 (1957).

 30.  Skogerboe, G.  V., Hyatt,  L.  M.  and  Eggleston,  K.  0,,  "Design  and
      Calibration  of Submerged Open  Channel Flow  Measurement Structures -
      Part 1,  Submerged Flow," Utah  Water Research Laboratory,  College of
      Engineering, Utah State University,  Logan,  UT,  Report  WG 31-2
      February 1967).

 31.   Skogerboe, G.  V., Hyatt,  L.  M.,  England, J.  D.  and Johnson, J.  R., V
      Design and  Calibration of  Submerged Open Channel Flow Measurement
      Structures - Part 2, Parshall  Flumes," Utah Water Research Labora-
      tory, College  of Engineering, Utah  State University, Logan, UT,
      Report WG 31-3,  March  1967.

 32.   Chen, C-L., Clyde, C.  G., Chu, M-S.  and Wei, C-Y., "Calibration of
      Parshall Flumes  with Non-standard Entrance  Conditions," Utah Water
      Research Laboratory, College of  Engineering, Utah State University,
      Logan, UT, Report PRWG 102-1, March  1972.

33.   Ludwig, J. H. and Ludwig, R. G., "Design of Palmer-Bowlus Flumes,"
      Sewage and Industrial Wastes. Vol. 23, No. 9,  (September 1951)
     pp. 1096-1107.                                                •'

34.  Wells, E. A.  and Gotaas, H. B.,  "Design of Venturi Flumes in Cir-
     cular Conduits," Journal of the Sanitary Engineering Division
     ASCE Vol. 82, No. SA2,  (April 1956).        	— 	

35.  Diskin, M. H., "Temporary Flow Measurement in Sewers and Drains,"
     Journal of the Hydraulics Division,  ASCE Vol. 89,  No.  HY4
      (July 1963),  pp. 141-159.
                                  411

-------
36.  Skogerboe, G. V., Hyatt, M. L., Anderson, R. K. and Eggleston, K.
     0., "Design and Calibration of Submerged Open Channel Flow Meas-
     urement Structures - Part 3, Cutthroat Flumes," Utah Water Research
     Laboratory, College of Engineering, Utah State University, Logan,
     UT, Report WG.31-4, April 1967.

37.  Bermel, K. J., "Hydraulic Influence of Modifications to the San
     Dimas Critical Depth Measuring Flume," Transactions American Geo-
     physical Union, Vol. 31, No. 5 (October 1950), pp. 763-768.

38.  Robinson, A. R., "Water Measurement in Small Irrigation Channels
     Using Trapezoidal Flumes," Transactions ASAE, Vol. 9, No. 3
     (March 1966), pp. 382-385, 388.

39.  Gwinn, W. R., "Walnut Gulch Supercritical Measuring Flume," Trans-
     actions ASAE, Vol. 7, No. 3 (March 1964), pp. 197-199.          '

40.  United States Department of Agriculture, Agricultural Research
     Service, Field Manual for Research in Agricultural Hydrology. Soil
     and Water Conservation  Research Division, Agriculture Handbook
     No. 224(issued  June 1962, reviewed and  approved  for reprinting
     October  1968).

41.  Vanleer, B.  R.,  "The California Pipe Method of Water Measurement,"
     Engineering  News-Record, August 3, 1922  and August 21, 1924.

42.  Smoot, G. F.,  "A Review of Velocity-Measuring Devices,"  United
     States Department  of Interior, Geological  Survey  Open File Report
      (April 1974).

43.  Lin,  H.  and  Martin, L.  D.,  "Analysis  of  Integrating-Float Flow
     Measurement," Journal  of the  Hydraulics  Division, ASCE,  Vol.  94,
     No. HY5  (1968),  pp. 1245-1260.

 44.  Henke, R.  W., "What You Should Know About  Velocity Flow  Meters,"
      Control  Engineering. Vol.  5,  No.  6 (June 1958), pp.  95-100.

 45.  McVeigh, J.  C.,  "Measurement  of Liquid Flow in Pipelines," Indus-
      trial Electronics, Vol. 3, No. 1 (January 1965),  pp.  29-32.

 46.   Schlitchting, H.,  Boundary Layer Theory, McGraw-Hill Book Company,
      Inc., New York,  NY.  (1960).

 47.   Artz, B., "Industrial Flow Metering with Turbine Meters," Instru-
      ments and Control Systems, Vol. 32, No. 11  (November 1959),
      pp. 1712-1713.

 48.  Yard, J. S., "Characteristics and Uses of Turbine Flow Meters,"
      ISA Journal, Vol. 6, No. 5 (May 1959), pp. 54-57.
                                    412

-------
 49.  Buchanan, T. J. and Somers, W. P.,  "Discharge Measurements at
      M!*O? stations>  Surface Water Techniques. Book 3 Chapter 8
      (1969), U. S. Geological Survey, United States Department of the
      Interior, Washington, D. C.

 50.  Townsend, F. W. and Bluet, F. A., "A Comparison of Stream Velocity
      Deters,  Journal of the Hydraulics Division. ASCE Vol. 86, No. HY4
      (April 1960), pp. 11-19.    :        ~~~.	

 51.  Carter, R. W. and Anderson, I. E., "Accuracy of Current Meter Meas-
      urements,  Journal of the Hydraulics Division. ASCE Vol. 89  No  HY4
      (July 1963), pp. 105-115.~

 52.  Smoot, G. F. and Novak,  C.  E., "Calibration and Maintenance of
      Vertical-axis Type Current Meters," Techniques of Water-ReSourrPg
      Investigations,  Book 8 Chapter B2 (1968),  U.S. Geological Survey,
      United States Department of the Interior,  Washington, D. C.

 53.  Robinson, A.  R., "Evaluation of the Vane-Type Flow Meter " Agri-
      cultural  Engineering,  Vol.  44, No.  7 (July 1963),  pp. 374-3757^81.

 54.  Stapler,  M.,  "Drag-Body  Flow Meters," Instruments  and Control  Sys-
      tems^  Vol. 35, No. 11  (November 1962),  pp.  97-99.	   —

 55.  Replogle,  J.  A., "Target Meters for  Velocity  and Discharge Meas-
      urements  in Open Channels,"  Transactions ASAE. Vol. 11  No 6
      November-December 1968),  pp. 854-856,  862.~

 56.   Stanney,  J. W.,  "Fluidic Velocity Sensor," Instruments and Control
      Systems.  Vol. 42, No.  6  (June  1969) pp. 81-83T"	

 57.   Halsell,  C. M.,  "Mass  Flow Meters; A New Tool for Process  Instru-
      mentation,  ISA  Journal. Vol.  7, No. 6  (June 1960), pp. 49-62.

 58.   Ling,  S. C.,  "Measurement of Flow Characteristics by  the Hot-Film
      Technique," Thesis for the Department of Mechanics and Hydraulics
      Graduate College of the State University of Iowa, Ames, Iowa
      June 1955.                                                  '

 59.  Runstadler, P. W., Kline, S. J. and Reynolds, W. C.,  "An Experi-
     mental Investigation of the Flow Structure of the Turbulent Bound-
     ary Layer,  Stanford University Engineering Report MD-8,  June 1963.

60.  Harris, G. S., "A Cold Tip Velocity Meter," Journal of Scientific
     Instruments (London), Vol. 43 (1965), pp.  657-658.	'	\	~

61.  Laub, J. H.,  "Measuring Mass Flow With the Boundary Layer Flow
     Meter,   Control Engineering.  Vol.  4,  No. 3 (March 1957)
     pp. 112-117.                                            '
                                   413

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62.  Laub, J. H., "The Boundary-Layer Mass Flow Meter," Instruments and
     Control Systems, Vol. 34, No. 4 (April 1961), pp. 642-644.

63.  Barlow, R. I., "Problems in Flow Measurement," Instruments and
     Control Systems. Vol. 39, No. 3 (March 1966), pp. 129-131.

64.  Eshleman, P. W. and Blase, R. A., "A Thermal Wave'Flowmeter for
     Measuring Combined Sewer Flows," USEPA Research and Development
     Report No. EPA-R2-73-145 (March 1973).

65.  Shercliff, J. A., The Theory of Electromagnetic Flow Measurement,
     Cambridge University Press, New York, NY  (1962).

66.  Liptak, B. G. and Kaminski, R. K., "Ultrasonic Instruments for
     Level and Flow," Instrumentation Technology, Vol. 21, No. 9
      (September 1974), pp. 49-59.

67.   Spencer, E. A.  and Tudhope, J. S., "A Literature  Survey of the
      Salt-Dilution Method of  Flow Measurement,"  Institute of Water Engi-
      neers Journal,  Vol. 12,  No. 2  (1958), pp. 127-138.

68.   Cobb, E. D. and Bailey,  J. F., "Measurement of Discharge  by Dye-
      Dilution Methods," Surface Water Techniques. Book 1 Chapter 14
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      Interior, Washington, D. C.

 69.   Replogle, J.  A., Myers,  L. E.  and  Burst,  K. J.,  "Flow Measurements
      With Fluorescent Tracers," Journal of  the Hydraulics Division.
      ASCE Vol.  92, No.  HY5  (September 1966), pp. 1-15.

 70   Kilpatrick, F. A.,  "Dye-Dilution Measurements Made Under  Total Ice
      Cover on the Laramie River at Laramie,  Wyoming," Water  Resources
      Division Bulletin,  July-December 1967,  pp.  41-47.
   i                                          »•
 71   Schuster,  J.  C., "Canal Discharge  Measurements  With Radioisotopes
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 72.  Alger, G. R., "The Electrostatic Flow Meter," Proceedings of Inter-
      national Seminar and Exposition on Water Resources Instrumentation
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 73.  Engineering-Science, Inc., for the City and County of San Francisco,
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                                     414

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74.  Burgess and Niple, Limited, "Stream,Pollution and Abatement from
     Combined Sewer Overflows, Bucyrus,"Ohio," EPA Water Pollution Con-
     trol Research Series Report No. 11024 FKN 11/69 (DAST-32)
     (November 1969).                            .                ,

     Hayes, Seay, Mattern and Mattern for the City of Roanoke, Virginia,
      Engineering Investigation of Sewer Overflow Problem - Roanoke,
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     Weston,  Roy F., Inc., "Combined Sewer Overflow Abatement Alter-
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     University of Cincinnati, Department of Civil Engineering,  Divi-
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     (October 1970).                                       .   '   ».

     Black, Crow,  and Eidsness,  Inc.,  "Storm and Combined Sewer  Pollu-
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     Metcalf  & Eddy,  Inc.,  "Storm Water Problems and Control  in  Sanitary
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     Minneapolis-Saint Paul Sanitary/District,  "Dispatching System for
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     Alonzo B. Reed,  Inc., "Postconstruction  Evaluation of  Combined
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     (July 1971).                                                       '

     Envirogenics Company, "Urban Storm Runoff and Combined Sewer Over-
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79.
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                                  415

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85.  Kenosha Water Utility, Kenosha, Wisconsin, "Biological Treatment
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87.  Rohnert Park, California, City of, "Surge Facility for Wet and Dry
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88.  NawrocfcL, Michael A., Hittman Associates  Inc., "A Portable Device
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89.  Becker, Burton  C.,  Emerson, Dwight B., Nawrocki, Michael A., and
     State  of Maryland,  Water Resources Administration,   Joint Construc-
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90.  Borchardt,  Frank,  and Davis, Peter L., Henningson,  Durham & Richard-
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     Iowa," EPA R&D  Research Report No. EPA-R2-73-170,  (April 1974).

 91.  Leiser,  Curtis  P., for the Municipality  of Metropolitan Seattle,
   *  "Computer Management of a Combined Sewer System," EPA R&D Research
     Report No. EPA-670/2-74-022,  (July 1974).

 92.   Colston,  Newton V., Jr., "Characterization and Treatment of Urban
     Land Runoff," EPA R&D Research Report No. EPA-670/2-74-096
      (December 1974).

 93.  Marsalak, J., "A Technique for Flow Measurement in Urban Runoff
      Studies, "Proceedings of International Seminar and Exposition on
      Water Resources Instrumentation (in press), sponsored by IWRA in
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 SUPPLEMENTAL REFERENCES                                       .     ,

 Ackers, P. and Harrison, A. J. M.,  "Critical-depth Flumes for Measure-
 ments  in Open Channels."  Hydraulics Research Paper No. 5. Department of
 Scientific and Industrial Research, Wallingford,  Berkshire, England,
 April  1963.

 Addison, H., Hydraulic Measurements, 2nd edition, Chapman and Hall Ltd.,
 London (1946).
                                    416

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Allen,  C. M.  and  Taylor,  E. A.,  "The Salt Velocity Method  of Water Meas-
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                                   417

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                                   418

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                                   419

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Heidt, F. D. and Wengefeld, P. C., "Description and Properties of a
Gapacitive Measuring System for Varying Water Levels and Water Waves,"
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                                   420

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-------
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                                   422

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                                  423

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                                   TECHNICAL REPORT DATA
                            (Please read Instructions on the reverse before completing)
1. REPORT NO.
  EPA-600/2-75-027
                                                           I. RECIPIENT'S ACCESSIOWNO.
4. TITLE AND SUBTITLE

 SEWER FLOW MEASUREMENT  - A STATE-OF-THE-ART
 ASSESSMENT                               	
            5. REPORT DATE
              November 1975 (Issuing Date)
            6. PERFORMING ORGANIZATION CODE
 ', AUTHOR(S)

  Philip E. Shelley and  George A. Kirkpatrick
                                                           8. PERFORMING ORGANIZATION REPORT NO.
9, PERFORMING ORGANIZATION NAME AND ADDRESS.
 EG&G Washington Analytical Services Center, Inc.
 2150 -Fields Road
 Rockville, Maryland   20850
             10. PROGRAM ELEMENT NO.

              1BB034;ROAP 21ASY;Task 034
             11.

              68-03-0426
12. SPONSORING AGENCY NAME AND ADDRESS
 Municipal Environmental Research Laboratory
 Office of Research and Development
 U.S. Environmental Protection  Agency
 Cincinnati,  Ohio  45268
             13. TYPE OF REPORT AND PERIOD COVERED
              Final
             14. SPONSORING AGENCY CODE
              EPA-ORD
18. SUPPLEMENTARY NOTES
18. ABSTRACT
  A brief review  of  the characteristics of  storm and combined sewer flows  is  given,
  followed by a general discussion of the need  for such flow measurement,  the types
  of flow data required, and the time element in flow data.  A discussion  of  desirable
  flow measuring  equipment characteristics  presents both equipment requirements as
  well as desirable  features and includes an equipment evaluation sheet  that  can be
  used for a particular application.  A compendium of over 70 different  generic types
  of primary flow measurement devices, arranged according to the fundamental  physical
  principles involved,  is presented along with  evaluations as to their suitability
  for measurement of storm or combined sewer flows.  To illustrate the implementation
  of the physical principles, a number of commercially-available devices for  flow
  measurement are briefly described.  A review  of project experience  in  flow  measure-
  ment is presented  along with a summary of current and on-going research  efforts.
  Some thoughts on future areas of research and development are also  given.
17.
                                KEY WORDS AND DOCUMENT ANALYSIS
                  DESCRIPTORS
                                              b.lDENTIFIERS/OPEN ENDED TERMS
                          c.  COSATI Field/Group
  *Flow measurement, *Flowmeters, *Liquid
  flow, *0pen channel flow, *Pipe flow,
  Stream  flow,  Storm sewers, *Combined
  sewers, Overflows, Manholes, Outfall
  sewers, Sanitary engineering, Urban areas,
  *Water  pollution, Water quality,  Reviews
 Water pollution control,
 *State-of-the-art assess'
 ment, On-going research,
 *Equipment evaluation  .
     13B
18. DISTRIBUTION STATEMENT

  RELEASE  TO PUBLIC
19. SECURITY CLASS (ThisReport)'
 Unclassified	
21. NO. OF PAGES
     436
                                              20. SECURITY CLASS (This page)
                                               Unclassified
                                                                         22. PRICE
EPA Form 2220-1 (9-73)
                                            424
                                                     GOVERNMENT PRINTING OFFICE: 1975-657-695/5342 REGION NO. 5-II

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