Operations
Guide for Automatic
Air Monitoring Equipment
         U. S. Environmental Protection Agency

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FIELD OPERATIONS GUIDE FOR AUTOMATIC

      AIR MONITORING EQUIPMENT
           Second Printing
        Prepared from report
 provided on Contract No. CPA-70-124

                 by
PEDCo-Environmental Specialists, Inc.
       Suite 8 Atkinson Square
       Cincinnati, Ohio 45246
   ENVIRONMENTAL PROTECTION AGENCY
       Office of Air Programs
Research Triangle Park, North Carolina
           October  1972

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The APTD (Air Pollution Technical Data) series of reports is issued by
the Office of Air Programs, Environmental Protection Agency, to report
technical data of interest to a limited number of readers.   Copies of
APTD reports are available free of charge to Federal employees, current
contractors and grantees, and nonprofit organizations - as  supplies
permit - from the Office of Technical Information and Publications,
Environmental Protection Agency, Research Triangle Park, North Carolina
27711 or from the National Technical Information Service, 5285 Port
Royal Road, Springfield, Virginia 22151.
This report was furnished to the Environmental Protection Agency by

PEDCo-Environmental Specialists, Inc., in fulfillment of contract

number CPA-70-124.  The contents of this report are reproduced herein

with minor corrections as received from the contractor.  Mention of

company or product names does not constitute endorsement by the

Environmental Protection Agency.
            Office of Air Programs Publication No.  APTD-0736
                                   ii

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                           ACKNOWLEDGMENT

     Many Individuals and organizations have been helpful in carrying
out this study; for these contributions the project management extends
its sincere gratitude.
     The contributions of Messers. John Kinosian and K. Nishikawa of
the California Air Resources Board, Mr. Waymon Siu of the Bay Area Air
Pollution Control District, Mr. William Munroe of the New Jersey
Department of Environmental Protection, Mr. Donald Hunter of the New
York Department of Environmental Conservation, Mr. Frederick Masciello
of the New York City Department of Air Resources, and a dedicated group
of technical specialists in EPA, Office of Air Programs, were of
particular significance.
     Mr. Neil J. Berg, Jr., Environmental Protection Agency, served as
project officer, and Mr. Lawrence A. Elfers, PEDCo-Environmental
Specialists, Inc., the project manager.
                                  iii

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                       Table of Contents

                                                                Page
      List of Figures	   viii
      List of Tables  	   ix
1.0   Introduction  	    1
1.1   Objectives and Scope  	    1
1.2   Role of Air Quality Monitoring  	    3
2.0   Design of Automatic Monitoring System 	    5
2.1   Number of Monitoring Sites  	    5
2.2   Site Selection	    5
      2.2.1  Population Density 	   11
      2.2.2  Location of Emission Sources 	   11
      2.2.3  Meteorology	11
      2.2.4  Topography	12
      2.2.5  Site Description	12
2.3   Shelter Design	16
      2.3.1  Mobility	<	16
      2.3.2  Neighborhood Factors 	   17
      2.3.3  Physical  Requirements  	   18
      2.3.4  Cost Estimates	27
2.4   Sample Manifold Design  	   28
      2.4.1  Molecular Diffusion Design 	   29
      2.4.2  Conventional  Manifold Design 	   31
2.5   Remote Station Support Equipment  	   33
2.6   Selection of Monitors	33
                              1
      2.6.1  Suggested Performance Specifications
             for Automatic Monitors 	   38
      2.6.2  Recommended Monitoring Methods 	   38
      2.6.3  Principles  of Measurement  	   40
      2.6.4  Compilation of Specific Monitors  	   59

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                                                             Page
2.7    Installation of Monitors	59
       2.7.1  Monitor Location with Respect to Sample
             Manifold	61
       2.7.2  Monitor Location with Respect to Operation
             and Servicing	61
       2.7.3  Monitor Location with Respect to Power
             Requirements  	  62
       2.7.4  Monitor Location with Respect to Reagent, Fuel,
             and Waste Requirements  	  62
2.8    Initial Startup of Monitoring Equipment  	  62
       2.8.1  Preparation and Storage of Reagents 	  63
3.0    Calibration	65
3.1    Role of Calibration in Air Quality Monitoring  ....  65
3.2    Dynamic Calibration  	  66
       3.2.1  Permeation Tubes  	  67
       3.2.2  Standard Gases	72
3.3    Calibration of Flow Parameters	79
3.4    Static Response Checks 	  82
       3.4.1  Static Chemical Methods 	  83
      3.4.2  Static Electrical Methods 	  83
3.5   Dynamic Response Checks  	  84
4.0   Operation	85
4.1   Operational Performance Log—Check Lists	85
4.2   Data Logging	87
      4.2.1  Role of Data Logging	87
      4.2.2  Logging Pollutant Level 	  92
      4.2.3  Data Reduction and Validation	93
5.0   Maintenance	104
5.1   Role of Maintenance	104
5.2   Routine Maintenance of Automatic Monitors	104
5.3   Nonroutine Maintenance of Automatic Monitors 	 105
      5.3.1  Troubleshooting	105
5.4   Maintenance of Remote Stations 	 108
                                vi

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                                                             Page
6.0   Characteristics of Air Monitoring Equipment 	  110
6.1   Physical Characteristics  	  110
6.2   Measurement Principles  	  Ill
6.3   Performance Characteristics 	  112
      6.3.1  Environmental Requirements 	  113
      6.3.2  Measurement Output 	  113
      6.3.3  Dynamic Response 	  114
6.4   Glossary	115
7.0   References	124

Appendix A.  Compilation of Monitors  	  127
Appendix B.  National Primary and Secondary Air Quality
             Standards	136
Appendix C.  Conversion Tables  	  141
                              vii

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                               List of Figures
                                                                  Paae
1.   SAROAD Site Identification Form	  14
2.   Floor Plan, Remote Air Sampling Station	  20
3.   Molecular Diffusion Sampling Manifold	  30
4.   Conventional Manifold System	  32
5.   Schematic Diagram of a Typical Conductivity
        Monitor	  42
6.   Schematic Diagram of a Typical Colorimetric
        Monitor	  43
7.   Schematic Diagram of a Typical Coulometric
        Monitor	  45
8.   Schematic Diagram of a Typical Amperometric
        Moni tor	  47
9.   Schematic Diagram of a Typical Flame Photometric
        Sulfur Monitor	  49
10.  Schematic Diagram of a Typical Flame lonization
        Monitor	  51
11.  Schematic Diagram of a Typical Nondispersive
       Infarared CO Monitor	  53
12.  Schematic Diagram of a Typical Tape Sampler	  56
13.  Schematic Diagram of a Typical Integrating
        Nephelometer	  58
14.  Schematic Diagram of a Typical Gas-Phase
        Chemiluminescent Ozone Detector	  60
15.  Permeation Tube	  68
16.  Permeation Tube Dilution Apparatus	  71
17.  Portable Calibration Apparatus for Use with
        Permeation Tubes	  73
18.  Distribution System for Use with Standard
        Gases	  74
19.  Dilution Board Device	  76
20.  Ozone Source, Dilution, and Manifold System	  77
21.  Rotameter Calibration Data Sheet	  80
22.  Typical Rotameter Calibration Curve	  81
23.  Daily Operational Log (conductivity monitor)	  88
24.  Weekly Operational Log (conductivity monitor)	  89
25.  Monthly Operational Log (conductivity monitor)	  90
26.  Quarterly Operational Log (conductivity monitor)	  91
27.  SAROAD Hourly Data Form	  95
28.  SAROAD Daily Data Form	  96
29.  Operator's Log	  99
                                vm

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                               List of Tables
 Table
Page
   1.   Criteria for Classification of Air Quality
           Control  Regions	   6
   2.   Recommended Number of Air Quality
           Monitoring Sites	   7
   3.   Materials Used in Shelter Construction	  21
   4.   Typical  Electrical Requirements for a Remote
           Air Sampling Station	  24
   5.   Descriptive Factors to Consider for the  Comparison
           of Automatic Air Honitoring Equipment	  34
   6.   Installation and Operational Factors to  Consider
           for the Comparison of Automatic Air Monitoring
           Equipment	  35
   7.   Performance Factors to Consider for the  Comparison
           of Automatic Air Monitoring Equipment	  37
   8.   Suggested Performance Specifications for
           Automatic Monitors	  39
   9.   Recommended Methods for Air Quality Surveillance	  40
 C-l.   Correction of Observed Permeation  Rate to
           Standard Temperature (25.0° C)  for S02
           Permeati on Tubes	  142
 C-2.   Percent Transmission (%T) and Optical Density  (O.D.)	  144
 C-3.   Conversion Factors for Gas-Phase Concentrations—
           for Converti ng ppm to pg/m^	  145
 C-4.   Conversion Factors—Length	  146
 C-5.   Conversion Factors—Area	  147
 C^6.   Conversion Factors—Flow	  148
 C-7.   Conversion Factors—Weight	  149
 C-8.   Conversion Factors—Concentration	  150
 C-9.   Conversion Factors—Volume	  151
C-10.   Conversion Factors—Pressure	  152
C-ll.   Conversion Factors—Temperature	  153
C-12.   Conversion Factors—Time (mean solar)	  154
                                   IX

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              FIELD OPERATIONS GUIDE FOR AUTOMATIC
                    AIR MONITORING EQUIPMENT
1.0   INTRODUCTION
      Surveillance of air quality is an important function of any air
pollution control agency.  Initially the agency must determine the
magnitude and scope of its air pollution problem, i.e., the extent to
which air quality standards are being exceeded.  This data may then be
used to develop an effective emission control plan.  Following the
adoption of emission regulations, atmospheric surveillance is required
to evaluate the progress toward the attainment of air quality standards.
Additionally, for those areas prone to the occurrence of periods of
high air pollution (episodes), surveillance becomes a vital part of
the Emergency Action Plan.
      To fulfill the requirements for air quality data, as determined by
the implementation plan, most control agencies find it necessary to
measure the ambient concentrations of pollutants at a number of sampling
sites strategically located through the area.  At many sampling sites,
especially where the air quality standards are unlikely to be exceeded,
intermittent 24-hour integrated measurements suffice.  However, within
most regions it is necessary to make continuous measurements of pollutant
concentrations at one or more sampling locations.  This document is
intended as a guide to State and local air pollution control agencies
                               i
(hereafter referred to as agency) in the selection, installation, and
operation of automatic monitoring equipment.
1.1   Objectives and Scope
      Air pollution control agencies at all levels of government are now
conducting atmospheric monitoring activities to measure a wide range of
                                 1

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particulate and gaseous pollutants.  A survey of these activities in-
dicates that the pollutants most likely to be included in the monitoring
activities are particulates (both suspended and settleable); carbon
monoxide; hydrocarbons (total, methane); photochemical oxidants corrected
for NOp and S02J ozone; oxides of nitrogen (NO and N02); and sulfur
dioxide and sulfation rates.  This list of pollutants coincides with the
list of pollutants for which criteria and, in most cases, control tech-
nology documents have been published.  Of this list the administration
of the Environmental Protection Agency has established National Air
Quality Standards for S0?, NO-, particulate matter, CO, photochemical
oxidants corrected for  N0? and S02, and hydrocarbons corrected for
methane.
      This document presents a summary of the experience gained by control
agencies and other selected users over a number of years through the
operation of automated monitoring equipment.  Thus, the discussion is
limited to suspended particulates, carbon monoxide, hydrocarbons,
nitrogen dioxide, photochemical oxidants, ozone, and sulfur dioxide.
The document is essentially a state-of-the-art treatise on automated
equipment covering such things as:
      0  Selecting the number and location of sampling stations
      0  Shelter design
      0  Instrumentation specifications
      0  Calibration
      0  Installation of equipment
      0  Routine operation
      0  Maintenance
      0  Data logging

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      The detail in which the techniques and procedures are presented
is intended to be of value to administrative and technical personnel.
It provides the agrncy with information concerning installation and
operating costs, and personnel  requirements  necessary to implement the
monitoring program in a manner consistent with  budgetary limitations
and the need for air quality data.  The document also provides suffi-
cient detail concerning equipment specifications and operating
characteristics to serve as an operations handbook for technical
personnel.
1.2   Role of Air Quality Monitoring
      The need for adequate air quality data is important in the develop-
ment of implementation plans for controlling air pollution in Air
Quality Control Regions.  Initially, air quality measurements are
required to establish the extent by which air quality standards are
currently being exceeded and to establish a basis from which control
programs are formulated.  Once a plan for controlling pollutant emissions
has been developed and adopted, air quality data is one of the require-
ments for documenting progress toward the attainment of standards.
Finally, air quality monitoring is necessary to provide immediate infor-
mation during adverse meteorological conditions as required in an
Emergency Action Plan.
      The Clean Air Act of 1970 stresses the importance of air quality
surveillance as an integral part of the States' implementation plan.
Specifically Section 110(a)(2)(C) of the Act requires that,

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      "it [the Implementation plan] includes provision for
      establishment and operation of appropriate devices,
      methods, systems, and procedures necessary to (i)
      monitor, compile, and analyze data on ambient air
      quality and, (ii) upon request, make such data
      available to '".he Administrator;"
Recently, the Environmental Protection Agency  has summarized the
objectives of air quality monitoring.  Air quality surveillance within
a region must provide information to be used as a basis for the following
actions:
      (a)  To judge compliance with and/or progress made toward
           meeting ambient air quality standards.
      (b)  To activate emergency control procedures to prevent air
           pollution episodes.
      (c)  To observe pollution trends throughout the region including
           the nonurban areas.  (Information on the nonurban areas
           is needed to evaluate whether air quality in the cleaner
           portions of a region is deteriorating significantly and
           to gain knowledge about background levels.)
      (d)  To provide a data base for application in evaluation of
           effects; urban, land use, and transportation planning;
           development of abatement strategies; and development and
           validation of diffusion models.

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2.0   DESIGN OF AUTOMATIC MONITORING SYSTEM
2.1   Numberof Monitoring Sites
      Criteria for determining the number of monitoring sites required
 for  adequate surveillance  in an Air Quality Control Region were
 published  in the  Federal Register. Volume 36, No. 158, August 14, 1971,
                                       2
 by the  Environmental  Protection Agency.   The criteria are based upon the
 priority (I, II,  III)  assigned to a region.
      A  priority classification has been assigned to each AQCR for CO,
NOp, particulate matter, photochemical oxidants, and sulfur dioxide
according  to the criteria  presented in Table 1.  For particulate matter
and sulfur oxides the  classification criteria provide for priorities
of I, II, or III, while for CO, N02> and photochemical oxidants
priorities of either I or  III are assigned to a region.
      The minimum requirements for the establishment of an air quality
monitoring system based upon the priority classification of a region
are presented in Table 2.  One or more monitoring sites are required
for each of the five pollutants in a priority I region.  For regions
classified as priority II  or III, the minimum requirements provide for
monitoring suspended particulates and sulfur dioxide only with 24-hour
sampling every 6 days.
2-2   Site Selection
      Although few sites are ideally located for all pollutants, most
                             (
agencies, for purely economic reasons, find it necessary to consolidate
sampling equipment for a number of pollutants at each sampling site.
Within this restriction, the factors which most affect site selection
are:   geographical distribution of population, location of pollutant
emission sources,  meteorology,  and topography.

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             Table 1.  CRITERIA FOR CLASSIFICATION
                               OF
                  AIR QUALITY CONTROL 'REGIONS
Concentrations in micrograms per cubic meter (ppm in  parentheses)
Pollutant
Sulfur Oxides
annual arithmetic mean

24-hour maximum

3-hour maximum

Parti culate matter
annual geometric mean
24-hour maximum
Carbon monoxide
8-hour maximum
1-hour maximum

Nitrogen dioxide
annual arithmetic mean

Photochemical oxidants
1-hour maximum

Priority
I

>100
(.04)
>455
(.17)



- 95
>325

> 14a
-(12)
> 55*
(48)

>110
1.06)

>195
~(.io)
II
•
60-100
(.02-. 04)
260-455
(.10-17)
>1300
(.50)

60-95
150-325










III

< 60
(.02)
< 260
(.10)
<1300
(.50)

«. 60
< 150

< 14a
(12)
< 553
(48)

< no
(.06)

< 195
(.10)
  a Concentration  in  milligrams  per cubic meter.

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                       Table  2.   RECOMMENDED NUMBER  OF AIR  QUALITY MONITORING SITES
Classifi-
cation of
region
I





















II







III9




Pollutant
Suspended participates





Sulfur dioxide






Carbon monoxide


Photochemical oxidants

.
Nitrogen dioxide


Suspended partlculates



Sulfur dioxide



Suspended partlculates

Sulfur dioxide


Measurement
method1
High volume sampler



Tape sampler

PararosanlHne or
equlvalentd





Nond1spers1ve
Infrared or
equivalent6
Gas phase chemilumi-
nesence or
equivalent'
24-hour sampling
method (Jacobs-
Hochheiser method)
High volume sampler

Tape sampler

PararosanlHne or
equivalent*1


High volume sampler

PararosanlHne or
equlvalentd

Minimum frequency
of sampling
One 24-hour sample
every 6 days'


One sample every
2 hours
One 24-hour sample
every 6 days (gas
bubbler)*

Continuous


Continuous


Continuous


One 24 -hour sample
every 14 days
(gas bubbler)l>
One 24-hour sample
every 6 daysa
One sample every
2 hours
One 24-hour sample
every 6 days
(gas bubbler)'
Continuous
One 24 -hour sample
every 6 days3
One 24-hour sample
every 6 days
(gas bubbler)'
Region population
Less than 100,000
100,000-1,000.000
1, 000 , 001 -5, 000 .000
Above 5,000,000


Less than 100,000
100.000-1,000,000
1,000,001-5,000,000
Above 5,000.000
Less than 100,000
100,000-5,000,000
Above 5,000,000
Less than 100,000
100,000-5,000,000
Above 5,000,000
Less than 100,000
100,000-5,000,000
Above 5,000.000
Less than 100,000
100,000-1,000,000
Above 1,000,000













Minimum number of air
quality monitoring sites"
4
4+0.6 per 100.000 populationc
7.5+0.25 per 100,000 population^
12+0.16 per 100.000 popu1ationc
One per 250,000 populationc up to
eight sites.
3
2.5+0.5 per 100,000 por ^tionC
6+0.15 per 100,000 populationc
11+0.05 per 100,000 populationc
1
1+0.15 per 100,000 populationc
6+0.05 per 100,000 populationc
1
1+0.15 per 100,000 population*-
6+0.05 per 100,000 populationc
1
1+0.15 per 100,000 population^
6+0.05 per 100.000 population0
3
4+0.6 per 100,000 population0
10
3

1

3


1
1

1


Equivalent to 61 random samples per year.
 Equivalent to 26 random samples per year.
'Total  population of a region.  When required number of samplers includes a fraction, round-off to nearest whole number.

Equivalent methods are (1) Gas Chromatographic Separation-Flame Photometric Detection (provided Teflon 1s used throughout the instru-
 ment system in parts exposed  to the air stream),  (2) Flame Photometric Detection (provided  interfering sulfur compounds present  in
 significant quantities are removed), (3) Coulometrlc Detection (provided oxidizing and reducing interferences such as 03, N02. and
 H2S are removed), and (4) the automated PararosanlHne Procedure.

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00
                                   Table  2  (continued).   RECOMMENDED  NUMBER  OF  AIR QUALITY  MONITORING  SITES

                                                               (Footnotes continued)
           'Equivalent method 1s Gas Chromatographic Separation-Catalytic  Conversion-Flame  Ion1zat1on Detection.
            Equivalent methods are  (1) Potassium Iodide Colorlmetrlc Detection  (provided a  correction Is made for SO; and NO?), (2)  UV Photometric
            Detection of Ozone (provided compensation 1s made for Interfering substances),  and  (3) Chenilumlnesence Methods differing  from that of
            the reference method.
           9It Is assumed that the  Federal motor vehicle emission standards will  achieve and maintain the national standards for carbon monoxide,
            nitrogen dioxide, and photochemical oxldants; therefore, no monitoring  sites are required for these pollutants.
            In Interstate regions,  the number of sites required should be  prorated  to  each  State on a population basis.
           1A11 measurement methods, except the Tape Sampler method, are described  in  the national primary and secondary ambient air quality
            standards published In  the Federal Register on April  30, 1971  (36 F.R.  8186).   Other methods together with those specified under foot-
            notes (d), (e), and (f) will be considered equivalent If they  meet  the  following performance specifications:
                    Specification*
Range
Minimum detectable sensitivity
Rise time, 90 percent
Fall time, 90 percent
Zero drift

 Span drift

Precision
Operation period
Noise
Interference equivalent
Operating temperature fluctuation
Linearity
                                                                                          Pollutants
                                           Sulfur dioxide
0-2,620 ug/mS (0-1  ppm)
26 ug/m3 (0.01  ppm)
5 minutes
5 minutes
'1 percent per  day  and »2 per
 cent per 3 days
*1 percent per  day  and *2 per
 cent per 3 days
*2 percent
3 days
'0.5 percent (full  scale)
26 ug/m3 (o.Ol  ppm)
45' C
2 percent (full scale)
                                                                             Carbon monoxide
                                                                           .   I
0-58 mg/m3 (0-50 ppm)
0.6 mg/m3 (0.5 ppm)
5 minutes
5 minutes
*1 percent per day and *2 per-
 cent per 3 days
•1 percent per day and *2 per-
 cent per 3 days
J4 percent
3 days              i
-0.5 percnet (full scale)
1.1 mg/m3 { 1  ppm)
*5° C
2 percent (full scale)
                                                                        Photochemical  oxidant
                                                                     (corrected for  N02 and SO;)
0-880 ug/m3 (0-0.5 ppm)
20 ug/m* (0.01 ppm)
5 minutes
5 minutes
*1 percent per day and »2 per-
 cent per 3 days
*1 percent per day and »2 per-
 cent per 3 days
*4 percent
3 days
*0.5 percent (full scale)
20 Ug/m3 (0.01 ppm)
*5° C
2 percent (full scale)
                The various  specifications are defined as follows:
                Range:  The  minimum and maximum measurement limits.
                Minimum detectable sensitivity:  The smallest amount of input concentration  which can be detected as concentration approaches zero.
                Rise time 90 percent:  The Interval between initial response time and time to  90 percent response after a step increase in inlet
                 concentration.
                Fall time 90 percent:  The Interval between initial response time and time to  90 percent response after a step decrease in the
                 Inlet  concentration.
                Zero drift:  The change in Instrument output over a stated time period of unadjusted continuous operation, when the input concen-
                 tration 1s  zero.
                Span drift:  The change In Instrument output over a stated period of unadjusted continuous operation, when the Input concentration
                 is a stated upscale value.
                Precision:   The degree of agreement between repeated measurements of the same  concentration  (which shall be the midpoint of the
                 stated range) expressed as the average deviation of the single results from the mean.
                Operation period:  The period of time over which the instrument can be expected to  operate unattended within specifications.
                Noise:  Spontaneous deviations from a mean output not caused by input concentration changes.
                Interference equivalent:  The portion of indicated concentration due to the  total of the interferences commonly found in ambient
                 air.
                Operating temperature fluctuation:  The ambient temperature fluctuation over which  stated specifications will be met.
                Linearity:   The maximum deviation between an actual instrument reading and the reading  predicted by a straight line drawn between
                 upper  and lower calibration points.

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                Table 2 (continued).   RECOMMENDED NUMBER  OF MONITORING SITES

                                      FOOTNOTES  (continued)




* These specifications are  defined below  and  in  Section  6.0:

Range:   The minimum and maximum measurement limits.
Minimum detectable sensitivity:  The  smallest amount  of  input  concentration which can be detected as
 concentration approaches zero.
Rise time 90%:  The interval  between  initial  response time  and time to 90% response after a step
 increase in inlet concentration.
Fall time 90%:  The interval  between  initial  response time  and time to 90% response after a step
 decrease in the inlet concentration.
Zero drift:  The change in  instrument output  over  a stated  time  period of unadjusted continuous
 operation, when the input  concentration  is zero.
Span drift:  The change in  instrument output  over  a stated  period of unadjusted continuous operation,
 when the input concentration is a stated upscale  value.
Precision:  The degree of agreement between repeated  measurements of the same concentration (which
 shallbe the midpoint of the stated  range) expressed as  the average deviation of the single results
 from the mean.
Operation period:   The period of time over which the  instrument  can be expected to operate unattended
 within specifications.
Noise:   Spontaneous deviations from a mean output  not caused by  input concentration changes.
Interference equivalent: The portion of  indicated concentration due to the total of the interferences
 commonly found in ambient  air.
Operating temperature fluctuation: The ambient  temperature fluctuation over which stated specifications
 will be met.
Linearity:  The maximum deviation between an  actual instrument reading and the reading predicted by
 a straight line drawn between upper  and  lower calibration  points.

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10

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      2.2.1   Population Density
      The most obvious location for a continuous monitoring station  is
in the central business section of a city.  In many cases this  site  not
only reflects the contribution of sources throughout the city,  but ol^o
provides an indication of human exposure.  If more than one continuous
monitoring station is to be installed, other areas in the city  with
high population density should be considered.  Population density maps
are usually available from official planning agencies in the area.  In
selecting an area of the city on the basis of dense population, considera-
tion should also be given to the location of pollution sources.  It  is
always best if a sampling site fulfills more than one objective.

      2.2.2   Location of Emission Sources
      Generally the reason for locating a continuous monitoring station
is to obtain representative data for an area; therefore, it is  important
that the site is not unduly affected by a dominant point source.
The station should not be located in the downwash (the downward motion
of air due to the lower pressure on the lee side of a structure) of  an
adjacent building—generally no closer than twice the height of the
building.
      2.2.3   Meteorology
      The ability of the atmosphere to transport and diffuse air
pollutants is dependent upon a number of meteorological parameters
sucn as wind speed and direction, atmospheric stability, mixing depth,
                                  n

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etc.  From the standpoint of site selection, wind speed and direction
are probably most important since they tend to describe the general
movement of air masses through the area.
      For most regions the only meteorological data available are those
from the local airport weather station.  Such data are of prime
importance to provide information about macroscale weather systems.
Air pollution meteorologists tend to agree that meteorological conditions
at the local airport are not representative of the microscale meteorology
throughout the region.  Because of this, many control agencies include
meteorological instrumentation at one or more continuous air monitoring
stations.  It is strongly recommended that an agency which lacks
detailed meteorological data for candidate locations for continuous
monitoring sites should consult a meteorologist before making final
site selections.
      2.2.4   Topography
      For any land area, microscale meteorological conditions are signi-
ficantly affected by topographical features such as steep valleys and
prominent hills.  In urban areas the situation is further complicated
by the grouping of buildings and structures, the location of streets
and highways, and the heat island effect.  The probable effect of
topography on the transport of pollutants from major point sources to
candidate monitoring sites must be determined.
      2.2.5   Site Description
      A detailed description should be prepared for each monitoring
site.  The availability of such information will be of considerable
value in the interpretation of data obtained at a given site.
                                 12

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Furthermore, a site description may provide for a better comparison of
results between sites within a region or between regions.
      All control agencies which submit air quality data to the National
Aerometric Data  lank are required to use the SAROAD system (Storage
and Retrieval of Aerometric Data).    SAROAD is designed to permit
rapid retrieval of air quality measurements made anywhere in the United
States and consists of (1) comprehensive identification codes for
stations and pollutants, (2) a set of data reporting forms to
accommodate the variety of sampling and analysis procedures and
facilitate the transfer of data to punch cards, input programs and
the resulting data file, and (3) output programs used to list, summarize,
and analyze the stored data (Figure 1).  This form provides detailed
information about location including address and grid coordinate
(Universal Transverse Mercator), name of operating agency, and pertinent
information about the type of area in which the site is located.
      It is  also  recommended for the agencies own information that each
monitoring  site  be  classified according to its exposure to pollution
 including motor  vehicle  emissions.  While these classifications will
 not necessarially appear on the SAROAD site identification form, these
 classifications  will  give  the agency insite into possible data  biasing
 by the  station.  Therefore each site may be assigned to one of the
appropriate categories as  listed  below:
      Category A.  Ground Level Station.  Heavy concentration—high
      potential for  pollutant buildup.  Site 10-15 feet from major
      traffic artery with local terrain features restricting ventilation.
      Sampler  probe  10-20  feet above ground.
      Category B.  Ground Level Station.  Heavy concentration—minimal
                                13

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                                   ENVIRONMENTAL PROTECTION AGENCY

                                      National Aerometric Data Bank

                                    Research Triangle Park, N. C.  27711


                                    SAROAD Site Identification Form
                                                                           .New!
                                                                                          Revised
                                n
            TO BE COMPLETE1" BY THE REPORTING AGENCY
                                                                          DO NOT WRITE HERE
                                                                        State     Area
                                                                                              Site
 (A).
               State
                                               Project
   I   23456   789   10


Agency      Project
                     City Name (23 characters)
                                                                               12  13
l37-5"               County Name (15 characters)

      City Population (right justified)
Region
                                                                                   Action
        52  53  54  05  56 57  58  59

                    Longitude

                  Deg.     Min.   Sec.
            W
                                                 Latitude
                                             Deg.   Mm.   Sec.
  60  61     62  63  64  65  66  67  68  69     70   II  It  73 74  75  76

UTM Zone      Easting Coord., meters        Northing Coord., meters
  60  61      62  63 64  65  66  67  68  69     70  71  72  73  74  75  76
                                                                        State     Area
                                                                                              Site
                  Supporting Agency (61 characters)
                    Supporting Agency, continued
                                                                    I    234567   89  1O

                                                                 Agency Pro ect       SMSA      Action
                                                                     II    I'  13    14   IS  16  17    80
 (C).
                                                                        State     Area
                                                                                              Site
    iu-79,     Optional:  Comments that will help identify


                  the sampling site (132 characters)
                                                                   £l
                                                                    123456789

                                                                 Agency  Project         Action
                                                                          m
                                                                     II      1?  13
 (D).
                                                                        State     Area
                                                                                               Site
                                                                     1    73456   189  10
                                                                  Agency  Project         Action

                                                                    D   m          n
                                                                        State     Area
                                                                                              Site
 (E).
               Abbreviated Site Address (25 characters)
                                                                    E|   I   I   I    I   I   FTTH
                                                                    1   '3456/89  10
                                                                          Project         Action
OMB No. 158-R0012

Approval expires 6/30/76
                                                                     II      I1*  13
                                                 (over)
              Figure  1.   SAROAD site  identification  form  (front).


                                                14

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                             SAROAD Site Identification Form (continued)
TO BE COMPLETED BY THE REPORTING AGENCY
                                                          DO NOT WRITE HERE
(F).
Check the ONE
major category that
best describes the
location of the
sampling site.
1.D CENTER CITY
2. CH SUBURBAN
3fd RURAL
4.O REMOTE
Specify
units	
Address, continued

  Next, check the subcategory
  that best describes the domi-
  nating influence on the sampler
  within approximately a 1-mile
  radius of the sampling site.
      1. Industrial
      2. Residential
      3. Commercial
      4. Mobile
      1. Industrial
      2. Residential
      3. Commercial
      4. Mobile
      1. Near urban
      2. Agricultural
      3. Commercial
      4. Industrial
      5. None of the above
               Elevation of sampler above ground
Specify
units	
                                                               State
                                                      Area
                             Site
   H4-S4I     Sampling Site Address (41 characters)
                                      _LL
                                                             123456789   10
                                                              Agency
                  Project
                 m
                Station Type
                                                                             County Code
                                                                           57  58  53   60
                                                                          AQCR Number
                                                                           61  62  63
                                                                               AQCR Population
    64   65  66  67   68   69   TO   71



          Elevation/Gr

          I    I   I    I
           72  73  74

                     Time
Elevation/MSL         Zone    Action
                                       75   76  77  78
                                                              79      SO
           Elevation of sampler above mean sea level

Circle pertinent time zone:    EASTERN    CENTRAL
MOUNTAIN   PACIFIC    YUKON    ALASKA   BERING

HAWAII
               Figure  1   (continued).   SAROAD  site
                                      identification  form  (back).
                                                     15

-------
      potential for pollutant buildup.  Site 15-50 feet from major traffic
      artery with good natural ventilation.  Sampler probe 10-20 feet above
      ground.
      Category C.  Ground Level Station.  Medium concentration.   Site
      50-200 feet fro \ major traffic artery.  Sampler probe 10-20 feet
      above ground.
      Category D.  Ground Level Station.  Low concentration.   Site 200
      feet or more from traffic artery.  Sampler probe 10-20 feet above
      ground.
      Category E.  Air Mass Station.  Sampler probe is between 20 and
      150 feet above ground.  Two subclasses: (!) good exposure  from
      all sides (e.g.  on top of building),  and (2)  directionally biased
      exposure (probe extended from window).
      Category F.  Poor site—adjacent to point source,  bad terrain,
      etc.; yields biased data not directly relatable to air  quality
      standards.
2.3   Shelter Design
      There is no single ideal shelter design for a remote air sampling
station.  The ultimate design depends on many factors including climate,
neighborhood, equipment design, and agency needs.  Rather than specifying
a standard shelter, this section will provide a master checklist of
design considerations to assist in the development of cost estimates
and specifications to meet individual requirements.
      2.3.1   Mobility
      The mobile capabilities of shelters are dictated by overall
program objectives.  If it is anticipated that the station will be at a
single location for many years, it would seem unnecessary to purchase
a mobile shelter.  However, city characteristics may change with time
and the station may need to be relocated to reflect shifting population
or industrial patterns.  There is a point at which a decision to require
                                  16

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shelter mobility must be made.  The Agency must first decide how the
facility  is  to be used.  This decision will fix many of the design
alternatives.
      2.3.2   Neighborhood Factors
      Owing  to the potential public relations value of a remote air
sampling  station, it is important that the shelter does not disrupt
the neighborhood or other surroundings.  Where the shelter is to be
located in a residential or rural area, aesthetics should be considered.
For example, a trailer may be objectionable in a residential neighborhood
but acceptable in an industrial area.  The color of the paint may be
obtrusive.  Restraint and good judgement should be exercised in the
use of exterior paint and signs.  The noise from high volume samplers
should also be considered.
      The character of the neighborhood will also dictate the use of
materials and related construction details.  Consider the impractica-
bility of having windows in neighborhoods which experience high
incidences of vandalism and theft.  Heavy industrial areas may not
present security problems so much as accidental breakage.  If windows
are used, the use of unbreakable clear plastics, in lieu of glass,
should be considered.
      The unavailability or high cost of desirable space and/or the
high incidence of theft or vandalism in certain neighborhoods make it
impractical to locate the monitoring station in a freestanding shelter.
The use of limited access public buildings such as schools or fire
stations should be investigated in these cases.
                                 17

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       2.3.3    Physical  Requirements
       Preliminary consideration of the physical requirements inherent
with the design, construction, and use of the remote sampling station
will ultimately result  in a configuration which will most efficiently
meet the specific needs of the agency.  The following considerations,
in this respect, should be made.
       2.3.3.1   General Design.  The shelter specifications must also
spell  out the necessary appurtenances.  These include foundation,
running gear,  stabilizing jacks, equipment platform, ladder, and
other  items.  Remember that equipment must fit through at least one
doorway.  Where applicable, standard construction material dimensions
should be kept in mind when designing the shelter.  As far as practical,
the design should be maintenance-free.  Since the shelter is small,
the material costs will generally be slight compared to the labor
involved.  Therefore, the use of high grade materials will not
appreciably affect the overall cost.  On the other hand, rapid dete-
rioration of the shelter will result in costly maintenance and loss
of public relations value.
      Standard construction methods should not be overlooked.  While
modular semipermanent structures may seem practical, they are costly.
The added initial  cost is offset if the shelter is moved periodically.
However, if a station is planned to be a fixed location, consider a
permanent building.  Standard construction methods can result in not
only less initial  cost, but less maintenance as well.
      2.3.3.2   Space Requirements.  Space will be dependent upon the
specific needs of the Agency.  In most cases where the remote station
                                18

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is used without additional support laboratory facilities, additional
space will be required.  Mobile facilities are somewhat limited in space
and this should be considered.  In general a self-sustaining remote
air sampling station will require, as a minimum, the following space:

      Instrumentation and laboratory area       150 sq. ft.
      Work area (desk and sink)                  30
      Compressed gas cylinder storage            15
      Miscellaneous storage                      10
      Toilet facilities                          15	
                                                220 sq. ft.

See Figure 2 for a suggested layout.  In addition, an elevated surface
of approximately 40 square feet is required for related sampling
equipment.  This equipment may include a meteorological package
complete with a retractable tower, a hi-vol sampler, and static
devices such as the dustfall bucket and sulfation plate.  This area
should have limited access by either stairs or a ladder.  This space
can be either the building roof or a separate structure.  Note, however,
that where the roof space is to be utilized, suitable roofing materials
and structural support must be provided.
      2.3.3.3   Materlals Requirements.  This section will give the
reader a general idea of suitable materials for the shelter; however,
detailed specifications are not within the scope of this manual.
Table 3 presents the types of materials suitable for each of the major
elements of the various shelters.  In some instances where alternatives
are available, more than one material is Listed.
                                 19

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Figure 2.   Floor plan,  remote air sampling  station.

1
— *
o
1
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=



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1



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r* • '••
o — —
r/
POO
Oe/» o
£1
(~\ 2 =
LJ ȣ
ooo
22' - 0"
IT - 0"

Bench Mounted
Instruments
2'-0"
o
o
in
(D
<-«•
3'-0"


7^
Rack Mounted
Instruments
Service Chase
for Instruments
0
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IN>
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-------
Table 3.  MATERIALS USED  IN SHELTER  CONSTRUCTION-
Element
Foundation
Floor structure
Finished flooring
Wall structure
Outside wall finish
Inside wall finish
Roof structure
Roofing membrane
Finished ceiling
Insulation
Type of Shelter
Mobile
Gravel pad
Concrete pad
Steel
Wood
Vinyl
Asbestos
tile
Carpet
Steel
Wood
Aluminum
Finished
plywood
Steel
Wood
Aluminum
\
Acoustical
tile
Fiberglass
Prefab-
ri cated
Concrete
piers
or
blocks
Steel
Wood
Vinyl
Asbestos
tile
Carpet
Wood
Plywood
Finished
plywood
Finished
plywood
Drywal 1
Plaster
Wood
Bull tup
Rubber
Smooth
asphalt
Acoustical
tile
Foil backed
fiberglass
batts
Conven-
tional
Concrete
footings
Concrete
Vinyl
Asbestos
tile
Concrete
Carpet
Wood
Masonry
Plywood
Masonry
Finished
plywood
Plaster
Masonry
Bar joist
Wood
Concrete
Bull tup
Rubber
Smooth
asphalt
Acoustical
tile
Plaster
Exposed bar
joist
Foil backed
fiberglass
batts
                          21

-------
      Additionally, specifications are required for certein minor items.
As was previously stated, where windows are desirable, a high grade
clear acrylic is suggested in lieu of glass.  In many respects a sky-
light can achieve the same psychological affect as a window and
therefore should not be overlooked.  However, natural light may affect
the chemical reaction in certain monitoring instruments.  Where such
instruments are used* it is advisable to exclude all natural light.
If the shelter roof is planned to be used as a working surface, specify
a material suitable for pedestrian traffic to be installed over the
roofing membrane.  This material will vary according to the type of
membrane used.
      Quality of the materials should also be considered.  As was
previously stated, the shelter should be as maintenance-free as possible.
Two items that are often overlooked in this regard are the doors and
the hardware.  Specify a high quality door which is designed for
exterior use.  Either solid wood or metal can give years of trouble-
free service.  Likewise the door hardware should be of high quality.
Since the hardware should be of high quality, the standard hardware
found in many of the newer office complexes and residences is not
recommended.  If the proper door is used, it will be heavy; therefore,
three or possibly four ball-bearing-type hinges should be used for
each door.  The door should be protected with adequate kick plates
and push plates—especially where equipment is to be moved in and out.
Door closers should be of adequate size, allowing for wind loads on
exterior doors.  Finally, the lockset should be a heavy duty mortise
type.  The lockset function would normally be "Inside open at all times;
                                 22

-------
lock with thumblatch on inside; unlock outside with key."  Note that
all shelters should be on the same key system, either keyed alike or
master keye<"'.  Generally all locks used on the doors of any one
shelter should be keyed alike.
      2.3.3.4   Electrical Requirements.  Owing to the nature of the
air sampling station, it is important that adequate power be supplied
to the shelter.  Total required power depends on the quantity and type
of equipment to be used.  In general 240-volt single-phase service is
required for air conditioning and a water still.  Both the air condi-
tioning unit and the still will generally require separate 30-ampere
circuits.  Whether 240-volt service is required for any other purpose
depends on the instruments used.  It is unlikely that the instruments
will require more than 120-volt service.  Individual circuit breakers
should be provided for all instruments.  Typical electrical require-
ments for a remote air sampling station are shown in Table 4.  Total
service requirement should be single-phase, three-wire, 105 amperes
at 240-volts.  This requires a No. 2 service entrance cable.  The load
center should have a 125-ampere main with 16 spaces.  This will provide
six spare spaces for use in the event that 240-volt equipment is added.
      Since the instrumentation is adversely affected by voltage
fluctuations, it is recommended that all sophisticated instrumentation
be powered by a regulated source.  Pumps, lights, high-volume samplers,
                                i
heaters and the like may be on nonregulated circuits.  Since proper
ampere loading is important for efficiency, a constant-voltage
transformer such as one manufactured by Sola Electric Division,
Sola Basic Industries, or equivalent, providing at least 30 amperes
of regulated power is required.

                                 23

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        Table 4.  TYPICAL ELECTRICAL REQUIREMENTS FOR A
                   REMOTE AIR SAMPLING STATION
Item
Air conditioner
Still
Lights
Instruments
(including
roof outlets)
Hot water
heater
Pumps and misc.
Quantity
1
1
1 kW
15
Duplex
1
10
Service
240 V,
240 V,
120 V,
120 V,
120 V,
120 V,
30 A, 10
30 A, 10
10 A, 1(6
30 A, 10
15 A, 10
20 A, 10
Comments


Fluorescent; all
on one circuit
Instruments plug
into wall outlets


      Exterior outlets should be located at the elevated work platform
only.  The added cost of installing ground level outlets is not warranted
since ground-level equipment is seldom used.  Electrical power at ground
level can be supplied by means of extension cords.  The outlets must
be waterproof; use a NEMA watertight box.  A telephone outlet should
also be provided for.
      Use electricity for heating purposes, even if gas or oil is
available, since combustion processes will form pollutants which will
adversely affect true ambient conditions.
      Note that the requirements for electrical construction and
inspection vary.  In general, construction must follow the National
Electric Code.  Local codes may be more restrictive.  Some may allow
nonmetallic sheathed cable.while others require the wiring to be put
in metallic conduit.  Prefabricated structures must often be inspected
prior to installing the interior wall finish.  Regardless of the
                                24

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standard wiring procedures used by the shelter manufacturer, the Agency
must conform with State and  local codes.  Deficient specifications in
this regard n =»y result in a  costly field change.
      2.3.3.5   Plumbing Requirements.  A remote air sampling station
should have a  laboratory-type sink.   If water  is not available or if
it is not  known where the stations are to be sited, provision should
be made for water storage.

      Toilet facilities consisting of a water  closet and  lavatory
are generally  required; however,  this is a  costly  item.   Permanent
stations may be able to utilize existing facilities nearby.  Normally,
if the station requires a full-time  attendant, toilet facilities should
be provided.   Shelters having mobile capabilities  should  also have
facilities for toilet hookup.
      2.3.3.6   Noise Considerations.  New  instrumentation may not
present a  noise problem.  However, older equipment may generate a
considerable amount of pump  noise.   Noise should be kept  at a minimum
and in no  case should be noise level  at the attendant's desk exceed
65 dB on the A scale.*  If pumps  are unduly noisy, one solution lie-..
in disconnecting the individual pumps and running  all the instruments
off a common isolated pump.  Where this solution is used, a standby
pump must  be provided to avoid loss  of data should the main pump fail.
The standby pump should be activated automatically by means of a
*Accoustical standards  have been established pertaining  to three
 weighing characteristics, designated A,  B, and C.  The  A network
 discriminates  against  very low frequencies; therefore,  it is employed
 to determine speech  interference  levels.
                                  25

-------
pressure switch in the vacuum line.  An alternate solution would be to
place a sound barrier between the attendant's work area and the
instrument area or t> isolate each pump in a second absorbing container.
      Sound absorbing materials are also helpful when used in the area
in which the noise is generated.  Acoustic tile is a good material to
use on the ceiling while a practical type of synthetic fabric carpeting
on the floor would be helpful.
      2.3.3.7   Heating and Air Conditioning.  Since the purpose of the
station is to sample the ambient air, it is imperative that the station
does not in any way affect the air quality; therefore, heating and
cooling should be done electrically.  This can be done by means of a
heat pump or an air conditioning (cooling) unit with electric resistance
heaters.  The latter is recommended because of the higher maintenance
required for heat pumps.
      Air distribution within the shelter must be designed to prevent
the air from blowing directly on the instruments.  Even distribution,
without drafts, is necessary.
      2.3.3.8   Security.  Security problems were alluded to in the
previous discussions relative to windows, doors, and hardware.  In
some areas it may be desirable to maintain a night light inside the
shelter and/or floodlighting outside the shelter.  Additional security
requirements may be desirable in the form of a perimeter fence.  This
is an item to be handled on a case-by-case basis.
      2.3.3.9   Safety.  Various safety regulations will apply to the
shelter and specific requirements are generally promulgated by the
Industrial Commissions of the States in which the shelters are to be
                                 26

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used.  If there are no applicable state standards, the requirements
of the National Fire Prevention Association should be followed.   In
general, there should be two exits to preclude trapping the attendant
in the event of fire.  Other items to consider are steps, ladders,
handrails around elevated work areas, and proper storage facilities
for gas cylinders.  Since gas cylinders must be fastened upright at
all times, specific facilities must be provided for this purpose.
The use of electrolytic hydrogen generation in lieu of compressed
hydrogen in tanks is recommended.
      A multipurpose dry chemical fire extinguisher (ammonium phosphate
type) should be provided and located in an unobstructed area near an
exterior door.  Such an extinguisher can be used on Class A, B,  and
C fires; a 10-pound size should be sufficient.  It is highly recommended
that the extinguisher be one which is listed or labeled by a nationally
recognized testing laboratory such as Underwriters' Laboratories.
      2.3.4   Cost Estimates
      Varying price conditions throughout the country and the
instability of construction costs make it impossible to pinpoint the
costs of a shelter.  A fair estimate would be in the range of $30 to
$40 per square foot.  This estimate is based on providing facilities
for toilet, heating, cooling, sink, and auxiliary elevated work
platform.  The cost of providing security fencing, automobile parking,
                                 I
and cabinetry has not been included.
      Mobile facilities are the most costly, initially, and conventional
construction would be the least costly.  However, this is dependent on
the labor situation.
                                 27

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      Because of the high cost of these shelters, the use of public
buildings should be considered.  Where plumbing and electrical
facilities are existent, necessary remodeling costs should run about
$10 to $15 per .square foot.
2.4   Sample Manifold Design
      Continuous monitors contained within the station must be supplied
with sample air which represents, in real time, the ambient atmosphere
under investigation.  To accomplish this requirement care must be
exercised in the selection of the manifold system.  Several variable
parameters affecting the sampling manifold design are the diameter,
length, flow rate, pressure drop, and materials of construction.  A
             4
recent survey  of current practice in continuous air monitoring stations
indicates that typical values of sampling intake line diameter, length,
and flow rate were 1.2 cm,.7 meters, and 5 liters per minute,
respectively.  In most applications, these physical parameters would
not be optimal and, therefore, are not recommended for use.  The
majority of these sampling lines were constructed of glass, stainless
steel, or Teflon.
      Losses within the sampling line can occur from reaction of the
desired constituent with the manifold material and/or with deposited
particulate materials on the walls of the manifold.  Two system designs
are used to minimize losses within the sample manifold; one is based
on molecular diffusion theory and the other, a more conventional design,
is based on utilization of nonreactive materials and good housekeeping
practices.
                                 28

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      2.4.1  Molecular Diffusion Design5
      The transport of gases and small particles,  in laminar  flow  down
a vertical sarmling inlet line with no bends, is by molecular diffusion.
A reasonable assumption for a sampling probe of any material  (even
glass), if it is coated with a deposition of urban aerosol,  is that
the surface could act as a perfect absorber--i.e., the concentration
is zero at the surface.
      By the proper selection of a large diameter vertical  inlet probe
and maintaining a laminar flow throughout it, the sample air is not
permitted to react with the walls of the probe.  Removable sample
lines constructed of Teflon or glass can be used to provide each
instrument with sample air.  These sample lines will require periodic
cleaning or replacement.  In fact it is good practice to clean sample
lines before the initial use.  A flow rate of 5 liters per minute
in 1.5 cm diameter tubing (commonly used in monitoring stations) is
not satisfactory for this application because of almost complete
diffusion losses.
      Diameters from 1.5 to 2.5 cm with 50 to 150 liters per minute
are unacceptable because of high pressure drops.  Therefore, inlet
line diameters of 15 cm with a flow rate of 150 liters per minute
are necessary if diffusion losses and pressure drops are to be
minimized.  This ensures that the inlet sampling probe collects and
transports pollutants with minimal alteration from the condition
and composition in which they existed in the atmosphere to the point
of instrumental analysis.  Such sampling ducts can be made of plastic,
aluminum, or other similar materials.  Figure 3 is an example of a
molecular diffusion sampling manifold.

                                 29

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 o
 <•*>
                     1 5 cm
                         G=~--
                                    Roof
                                       Sample  Ports
             Blower    150 1/mln
Figure 3.  Molecular diffusion sampling manifold.
                       30

-------
      In this system an inexpensive blower is required to maintain the
air flow.  Not only is such a configuration easier to construct than
a glass system, but it also has the following advantages:
      0  A 15-cm pipe can be cleaned easily by pulling a cloth
         through it with a string.
      0  Sampling ports can be cut into the pipe at any location
         and, if unused, can be plugged with stoppers.
      0  Metal poses no breakage hazard.
      0  The pipe does not have to be clean to provide a
         representative sample, as in the case with smaller
         tubes.
      0  It is unnecessary to use a supposedly inert material by
         proper choice of size and flow rate.
      2.4.2   Conventional Manifold Design
      In practice it may be difficult to obtain the vertical laminar
flow required for the molecular diffusion design because of the
necessary elbows within the intake manifold system.  Therefore, the
conventional system is proposed which employs inert materials such as
Pyrex glass and/or Teflon as the transport medium.  The manifold should
be designed in modular sections to enable frequent cleaning.  (In
relatively dirty urban areas, monthly cleaning is recommended.)  The
system  (see figure 4) consists of a vertical "candy cane" protruding
through the roof of the shelter.  The horizontal sampling manifold is
connected by means of a tee to the vertical section.  Connected to
the other vertical outlet of the tee is a bottle which serves to collect
heavy particles and moisture before they can enter the horizontal
sections.  A small blower (60 cfm at 0.0 inches of water static
pressure) is placed at the exhaust end of the system.  This will
provide a flow  through the system of approximately 3 to 5 cfm.
                                 31

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                                               Roof
                    -3—3-Q&	ft	ft-gra	a—*-
—  Blower
          Modular  Section
                                                    24"
Moisture Trap
             Figure 4.  Conventional manifold system.

       A high mass/velocity ratio  within this system will  reduce the
 sample residence time within the  manifold and additionally will provide
 a minimum  pressure drop therein.   This can be achieved by employing
 large (50  mm or greater inside diameter) Pyrex glass  tubing.  The
 mass flow  within the system should be approximately 3 to  5 times the
 total sample requirements of all  the monitors connected to the system.
 Parti cu late  monitoring instruments, such as paper tape samplers and
 nephel ometers , should be provided with a separate intake  probe.  The
 probe should be so constructed that it is as short and as straight
 as possible  to avoid particulate  losses due to impaction  on the walls
 of the probe.
                                32

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             789
      Studies ' '  have been conducted to determine the suitability of
materials, such as polypropylene, polyethylene, PVC, Tygon, aluminum,
brass, stainless steel, copper, Pyrex glass, and Teflon for use as
intake sampling lines.  Of the above materials, only Pyrex glass and
Teflon are acceptable for use as  intake sampling  lines  for  all
continuous monitoring equipment.   However,  Teflon has been  found
to be unsuitable in the sampling  and analyses  of  mercury.
2.5   Remote Station Support Equipment
      Equipment provisions for reagent preparation and  instrument
calibration should also be considered.  The magnitude of this require-
ment will vary depending on the number of remote stations, their
proximity to each other and to a central support laboratory.  In all
cases, equipment such as an analytical balance, colorimeter, calibration
equipment, and a source of pure water  (distilled or deionized) will be
required to support the remote station.  Much of this equipment could
be maintained at a central support laboratory and used as needed in
the field.
2.6   Selectionof Monitors
      Selection of continuous monitoring equipment should be made
following a careful evaluation of published information pertaining to
the instrumental specifications and a knowledge of the user's specific
application.  To aid the prospective user in making an objective
comparison of instrumental specifications and performance
characteristics, a comprehensive list of these factors has been
developed.   For convenience, the factors are presented in Tables 5,
6, and 7.  Table 5 covers descriptive factors needed to identify the
instrument such as name of manufacturer, trade name, model number,
                                  33

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         Table 5.  DESCRIPTIVE FACTORS TO CONSIDER FOR THE

          COMPARISON OF AUTOMATIC AIR MONITORING EQUIPMENT
                      Instrument description
Term or specification
     Information required
Manufacturer and/or vendor(s)
Trade name and/or model no.
Application
Measurement principle
Schematic diagram



Auxiliary equipment
Name and address of manufacturer
or vendor(s) if manufacturer is
to be unlisted.

Trade name and/or model number
applied by the manufacturer or
the vendor.

Purposes and use for which the
instrument is designed (e.g.,:
source or emission monitor, process
control, chamber, ambient air
monitor).

Brief, concise, simple explanation
of the principle upon which the
measurement is based; also includes
information such as wavelength,
detection principle, reagent(s),
etc.

A simple diagram of the basic flow
and, where applicable, electronic
circuits.

A listing of the peripheral items
needed to make the instrument
operational; may include display
units, amplifiers, pumps, pressurized
cylinders of gases, reagents, etc.,
which are not a part of or contained
within the analyzer cabinet.   (See
definition, section 6.0.)
                                  34

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   Table 6.  INSTALLATION AND OPERATIONAL FACTORS  TO CONSIDER  FOR

        THE COMPARISON OF AUTOMATIC AIR MONITORING EQUIPMENT
                    Installation and operation
Term or specification
     Information required
Space requirements

Weight

Power requirements
Temperature operating
  range

Humidity operating
  range

Vibration operating
  range

Portability
Signal output
Air sampling rate
Sample line pressure
(See definition, section 6.1}

(See definition, section 6.1)

Electrical power needed—voltage(s]
AC and/or DC, frequency, wattage,
or current.

(See definition, section 6.3)


(See definition, section 6.3)


(See definition, section 6.3)
Specify if unit is designed or
may be adapted for portable or
mobile operation.

The signal output from the analyzer
or detector.  Specify form of
signal voltage(s), current, power,
and whether output is linear or
nonlinear.  If nonlinear, specify
whether exponential or other
unspecified function.

Rate of sample air flow in volume
per unit time, usually millimeters
per minute or liters per minute.

The range of pressure within the
sample line, usually negative, over
which the instrument will need
performance specifications.
                                 35

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  Table 6 (continued).  INSTALLATION AND OPERATIONAL FACTORS TO

  CONSIDER FOR THE COMPARISON OF AUTOMATIC AIR MONITORING EQUIPMENT
Term or specification
     Information required
Sample line construction
Reagent flow rate
Reagent consumption
  (weekly)
Calibration
Internal diameter, length, and
material of air sample line
through which the sample may
pass and meet instrument performance
specifications.

Flow rate of all critical chemical
reagents in volume per unit time,
usually milliliters per minute.

Volume of reagent consumed by the
analyzer per unit time, usually in
milliliters or in liters per week.

Frequency and type of calibration
needed for the instrument to maintain
performance specifications.  Cali-
brations may be performed statically
with resistors, screens, optical
filters, electrical signals,
standard calibrating solutions, or
dynamically with a gas of known
concentration.
                                 36

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        Table 7.  PERFORMANCE FACTORS TO CONSIDER  FOR  THE
         COMPAR SON OF AUTOMATIC AIR MONITORING  EQUIPMENT
                   Performance characteristics
Term of specification
     Information  required
Accuracy
Minimum detectable
  sensitivity
Minimum detectable
  change
Precision
Reproducibility
Linearity
Zero drift
Span drift
Noise
Range(s)
Initial response time
Rise time
Time to 95% response
Fall time
Response time constant
Warmup time
Interference(s)
Interference equivalent
(See definition,  section  6.3)
(See definition,  section  6.3)
(See definition,  section  6.3)
(See definition,
(See definition,
(See definition,
(See definition,
(See definition,
(See definition,
(See definition,
(See definition,
(See definition,
(See definition,
(See definition,
(See definition,
(See definition,
(See definition,
(See definition,
section 6.3)
section 6.3)
section 6.3)
section 6.3)
section 6.3)
section 6.3)
section 6.3)
section 6.3)
section 6.3)
section 6.3)
section 6.3)
section 6.3)
section 6.3)
section 6.3)
section 6.3)
                                 37

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the measurement principle used, etc.  Table 6 covers factors which
govern the installational and operational requirements such as size,
space, weight, power, temperature and humidity ranges, audible
instrument noise, air sampling rate, and maintenance needs (including
calibration method and frequency).   Table 7 covers performance
factors or the fidelity of instrument output in response to dynamic
changes in pollutant concentration.  Opposite each term in Tables
5, 6, and 7 is an explanation of the information to be obtained.
In some cases the terms are defined in Section 6.3, Performance
Characteristics.
      2.6.1   Suggested Performance Specification for Automatic Monitors
      Several performance specifications which should be considered in
selecting equipment are presented in Table 8.  All of the specifications
may not be required in all monitoring situations and the user will have
to use his best judgment in selecting specifications important to him.
The specifications of Table 8 are realistic and instruments are
currently available which can meet all of the specifications given.
For monitoring to determine compliance with air quality standards,
the user must be especially careful that the instruments measure
with sufficient sensitivity, specificity, precision, and lack of
drift.
      2.6.2   Recommended Monitoring Methods
      The Environmental Protection Agency   has published reference
methods for the measurement of sulfur dioxide, nitrogen dioxide, carbon
-cr.oxide, photochemical oxidants, and suspended particulates.   Table 9
is z sugary of these methods.
                                38

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                           Table 8.  SUGGESTED PERFORMANCE SPECIFICATIONS FOR AUTOMATIC MONITORS
Specification
Range

Minimum detectable
sensitivity
Rise time, 90%
Fall time, 90%
Zero drift

Span drift


Precision
Operation period
Noise

Interference
equivalent
Operating tempera-
ture fluctuation
Linearity
Pollutants
Sulfur dioxide
0-2620 yg/m3
(0-1 ppm;
26 yg/m3
(0.01 ppm)
5 min.
5 min.
± 1% p~er day and
± 2% per 3 days
(full scale)
t 1% per day and
± 2% per 3 days
(full scale)
± 2%
3 days
± 0.5% (full
scale)
26 Wg/m3
(0.01 ppm)
± 5° C

2% (full scale)
Carbon monoxide
0-58 mg/m3
(0-50 ppm)
0.6 mg/m3
(0.5 ppm)
5 min.
5 min.
± 1% per day and
± 2% per 3 days
(full scale)
± 1% per day and
± 2% per 3 days
(full scale)
± 4%
3 days
± 0.5% (full
scale)
1 .1 mg/m3
(1 ppm)
± 5° C

2% (full scale)
Photochemical
oxidant
(corrected for
N02 and SO?)
0-880 yg/m
(0-0.5 ppm)
20 yg/m3
(0.01 ppm)
5 min.
5 min.
±1% per day and
± 2% per 3 days
(full scale)
± 1% per day and
± 2% per 3 days
(full scale)
± 4%
3 days
± 0.5% (full
scale)
20 yg/m3
(0.01 ppm)
± 5° C

2% (full scale)
Nitrogen dioxide
0-1880 yg/m3
(0-1 ppm)
19 yg/m3
(0.01 ppm)
5 min.
5 min.
± 1% per day and
± 2% per 3 days
(full scale)
± 1% per day and
± 2% per 3 days
(full scale)
± 4%
3 days
± 0.5% (full
scale)
19 yg/m3
(0.01 ppm)
± 5° C

2% (full scale)
Hydrocarbons
(corrected
for methane)
o-3.3 mg/m
(0-5 ppm)
0.13 mg/m3
(0.20 ppm)
5 min.
5 min.
± 1% per day and
± 2% per 3 days
(full scale)
± 1% per day and
± 2% per 3 days
(full scale)
± 2%
3 days
± 0.5% (full
(scale)
0.032 mg/m3
(0.05 ppm)
± 5° C

2^ (full scale)
CO
vo

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         Table 9.   RECOMMENDED METHODS FOR AIR QUALITY SURVEILLANCE
                 Pollutant
       Suspended particulates

       Sulfur dioxide

       Carbon monoxide

       Nitrogen dioxide

       Photochemical  oxidants
         (corrected for N02 and

       Hydrocarbons (corrected for
         methane)
                       Recommended method3
                  High volume sampler

                  Pararosaniline

                  Nondispersive IR
                  Jacobs-Hochhei ser

                  Gas phase chemiluminescence
                    olefin ozone reaction

                  Flame iom'zation detector
        For equivalent  see  Table 2.

       2.6.3   Principles of Measurement

       As  a prerequisite for making  this  objective  evaluation, a  general

knowledge of the measurement  technique employed  by the various specific

monitors  is essential.  The following operational  principles are

commonly  incorporated  in continuous  air  monitoring instrumentation.

     2.6.3.1  Conductivity.  The principle for conduct!metry is  elec-
Ity.
JbTe
trie conductance by soluble electrolytes.  Although it has had wide
application as an analytical procedure in air-monitoring instruments,
the method is subject to gross interference and is not recommended.
The conductance of electrolytes in solution is proportional to the
number of ions present and their mobilities.  In dilute sample solutions,
the measured conductivity can be directly related to the concentration of
ionizable substance present.  Sulfur dioxide has been measured by this procedure
in continuous recording instrumentation for more than 25 years.  The
basic concept  involves absorption  of  sulfur  dioxide  in deionized water

(or a very dilute reagent)  to  produce an  acid  having conductance

sufficient to  be detected by a conductivity  cell.  Monitors employing

de-ionized water as  the  reagent result in the  formation of a mixture

of sulfurous and sulfuric acid.  Interferences  from  carbon dioxides, salt
                                 40

-------
aerosols, acid mists, and basic gases  are  common.  Most  sulfur dioxide
analyzers use distilled or de-ionized  water reagent modified by the addition
of hydrogen peroxide and a small amount of sulfuric acid.   This modified
reagent forms  .ulfuric acici (H2S04) upon reaction with sulfur dioxide.
THe acidic property of this modified reagent reduces  the solubility
of carbon dioxide gas within the reagent ana minimizes this interference.
Figure 5 is a schematic diagram of a typical conductivity-type monitor.
      2.6.3.2   Colorimetry.  Colorimetry can be defined as a mode of
analysis in which the quantity of a colored substance is determined by
measuring the relative amount of light passing through a solution of
that substance.  The constituent may itself be colored and thus be
determined directly, or it can be reacted with a reagent to form a
colored compound and thus be determined indirectly.
      The physical law that underlies colorimetric analysis is commonly
                             12
referred to as the Beers law.    It states that the degree of light
absorption by a colored solution is a function of the concentratior.
and the length of the light path through the solution.
      These principles are commonly employed for the continuous
measurement of three air pollutants; sulfur dioxide, nitrogen
dioxide, and oxidants.
      Figure 6 is a schematic diagram of a typical colorimetric type
monitor.  As shown, an atmospheric sample is drawn into the air-reagent
flow system, first entering the absorber or scrubber where the desired
constituent is reacted with the appropriate reagent.  The air sample
is separated from the reacted reagent and passed through the air pump
                                 41

-------
      Figure 5.  Schematic diagram of a typical  S02 conductivity monitor.
                              Capillary Liquid
                          rMetering Tube
                                 Air Meter
                                                    r-O
Sample
Air
   Soda-
   Lime
   Tube
                    Absorb!n
                     Column   |
I	|
      Liquid
      Check Cell
     Filler

     Constant
     Head Tube
   4— Liquid
       Supply
       Bottle
                                                                        Vacuum
                                                                         Pump
                                                                      Ml
                                          Air Relief  Air Flow
                                            Valve     Reg.  Valve

                                      •-Meter Overflow
                                      — Condensate
                                               Drain
                                                     Drain Cup

-------
Sample
                                                                          Reagent
                                                                          Reservoi r
                          Detection Circuit
                                Recorder

            Figure 6.   Schematic  diagram of a typical  colorimetric monitor

-------
and finally discharged to the atmosphere.  The reacted reagent passes
from the bottom of the absorber into the continuous flow colorimeter
where the absorbance of the solution is measured.  In most cases a dual
flow colorimeter, as shown, is employed whereby the absorbance of the
unreacted reagent is initially measured.
      2.6.3.3   Coulometry.  Coulometry is a mode of analysis wherein
the quantity of electrons required to oxidize or reduce a desired
substance is measured.  This measured quantity, expressed as coulombs,
is proportional to the mass of the reacted material according to
Faraday's law.  Coulometric titration cells for the continuous measure-
ment of sulfur dioxide, oxidants, and nitrogen dioxide have been
developed using this principle.  Figure 7 is a typical flow diagram of
a coulometric type monitor.
      One class of cells generally employed in continuous air monitoring
is designed to respond to materials which are oxidized or reduced by
halogens and/or halides.  Upon introduction of a reactive material,
the halogen-halide equilibrium is shifted.  The system is returned
to equilibrium by means of a third electrode which regenerates the
depleted species.  The current required for this generation is measured
and is directly proportional to the concentration of the depleted
species, which in turn is proportional to the quantity of desired
constituent.  This mode of analysis can be classified as secondary
Coulometry, usually employing a dynamic iodimetric or bromimetric
titration.  These systems are designed to respond with a sensitivity
in the lower parts-per-billion range.  Most commercial coulometric
systems are made specific by the use of prefiltration devices,
                                  44

-------
           Teflon
           Capillary
                           Glass Capillary
  Distilled
Water Reservoir
        Glass
      Capi 11-ary
  By-Pass
  Filter




Selective
Scrubber

Carbon
Filter



i
,
                            Solenoid
                             Valve
                        3-Way
                        Valve
y
V
_
7

Water Addition
System

AT-
I
V

(ft
,
M
\




j
Wat
                                   Detector
                                     Cell
                                                 Pressure  Reg
                                                                       Pulsation
                                                                        Dampi ng
                                                                        Volume
Pump
    Exhaust
           Figure 7.  Schematic diagram of a typical coulometric monitor.

-------
scrubbers, and/or chromatographic techniques that retain interfering
compounds and permit passage of the desired constituents.  Some loss of
pollutants may occur in these devices, probably not exceeding 10 percent.
      Another type of coulometric cell, designed for oxidant analysis,
employs amperometry.  The oxidant reacts with an iodide solution within
the cell releasing iodine which depolarizes the cathode, thus permitting
current flow which is proportional to the oxidant concentration.  By
passing reagent and sample over the electrodes, a continuous measurement
is achieved.  This type of monitor is also subject to interferences.
Materials which undergo oxidation will appear as negative interferences;
those that undergo reduction will appear as positive interferences.
Figure 8 is a diagram of a typical amperometric-type monitor.
      2.6.3.4   Flame Photometry.  Flame photometry is based on the
measurement of the intensity of specific spectral lines resulting from
quantum excitation and decay of elements by the heat of a flame.
Volatile compounds are introduced into the flame by mixing them
with the flammable gas or with the air supporting the flame.  Nonvolatile
compounds are aspirated from a solution into the flame.  The specific
wave length of interest can be isolated by means of narrow-band optical
filters, diffraction gratings, or by means of a prism.  The intensity
of the specific wavelength can be measured by means of a phototube or
photo-multiplier tube and associated electronics.
      Recent development of flame photometric detectors  *   having a
semi specific response to volatile phosphorus and sulfur compounds has
led to their use in continuous monitoring of gaseous sulfur compounds.
Tr.is flane photometric detector consists of a photo-mutiplier tube
                                 46

-------
                                             Reagent  Pump
a mm
\
eter

\



t
/'
Power Supply


-





-






J^
i=

=s:
§
§


?



1
J
V
x




X
X
X
X
t?




X
X
X
X
(
\

^Small An
Wire Cat
Electrod
Plastic
^xWire Ano
Samp!
^ (



\

                         Waste
                       Reagent
                                                o
                                                Sample Intake

                                               Annul us
                                                       ,i r Pump
Figure 8.  Schematic diagram of a typical amperometric monitor.
                             47

-------
 viewing  a  region  above  the flame  through narrow-band optical filters.
 When  sulfur  compounds are introduced into the hydrogen-rich flame,
 they  produce strong  luminescence  between 300 and 423 nanometers.  A
 specificity  ratio for sulfur to nonsulfur compounds of approximately
 20,000 to  1  is achieved with a narrow-band optical filter in the
 range between 5 ppb  and about 900 ppb.  Other sulfur compounds result
 in positive  interferences while monitoring for S02, since the detector
 responds to  all sulfur compounds.  Discretion should be used in
 interpreting data obtained from this detector when it is located in
 areas where  other sulfur compounds exist.  For example, H2S and CH^SH
 are found  in conjunction with S0~ in the vicinity of kraft paper mills
 and CS2 and H2$ in the vicinity of oil fields and refineries.  Figure 9
 is a schematic diagram of a typical flame photometric sulfur monitor.
      Separation of  parts-per-billion levels of S02, H2S, C$2, and
 CH^SH has recently become feasible through the use of chromatographic
 techniques.    This mode of separation followed by flame photometric
 detection of the separated sulfur compounds has led to the development
of a new type of semicontinuous monitor for sulfur contatning gases
which is specific and free from interferences.
      2.6.3.5   Flame lom'zation.  Instruments employing flame ionization
detectors, originally designed for gas chromatographic detection of
 organic compounds, have had wide application as a continuous monitor
 for hydrocarbons.  The sample to be analyzed is  mixed with a hydrogen
 fuel and passed through a small jet; air supplied to the annular space
 around the jet supports combustion.  Carbon-containing compounds carried
 into the flame result in the formation of ions.  An electrical potential
                                 48

-------
us
                                          Heated  Exhaust
                                          Filter
                                             Photomulti pi 1er
                                                   Tube
                                                Oxygen
                                                   Electrometer
                                                                    D.C. Power
                                                                      Supply
                  Figure 9.  Schematic diagram of a typical flame  photometric sulfur monitor.

-------
across the flame jet and an ion collector electrode produces an ion
current proportional to the number of carbon atoms in the sample.
      Advantages, inherent in this detector are that it is free from
interferences from inorganic gases, has a rapid response time, and has
a low "noise background" level.  Figure 10 is a schematic diagram of
a typical hydrogen flame ionization type monitor.
      Recent investigations involving automated gas chromatographic
separation of the air sample into three fractions has led to the
development of semi continuous monitor for CO, CH., and total
hydrocarbons.  Measured volumes of ambient air are delivered
periodically (4 to 12 times per hour) to a hydrogen flame ionization
detector to measure its total hydrocarbon (THC) content.  An aliquot
of the same air sample is introduced into a stripper column which
removes water, carbon dioxide, and hydrocarbons other than methane.
Methane and carbon monoxide are passed gravitatively to a gas
chromatographic column where they are separated.  The methane is
eluted first and is passed unchanged through a catalytic reduction tube
into the slave ionization detector.  The carbon monoxide is eluted into
the catalytic reduction tube where it is reduced to methane before
passing through the flame ionization detector.  Between analyses the
stripper column is backflushed to prepare it for subsequent analysis.
Hydrocarbon concentrations corrected for methane are determined by
subtracting the methane value from the total hydrocarbon value.
      2.6.3.6   Nondisperslve Infrared Photometry.  The infrared
absorption characteristics of several gases and vapors make possible
their detection and analysis in continuous analyzers.  Carbon monoxide
as an air contaminant is uniquely suited to this method of analysis,
                                 50

-------
Air
Supply
                    Regulator
          Hydrogen
          Generator
 Fl ame
Detector

J   L
Electrometer
                                          Sample
                Figure 10.  Schematic diagram of a typical flame ionization monitor.

-------
as its absorption characteristics and typical concentrations make
possible direct sampling.
      A typical analyzer (Figure 11) consists of a sampling system,
two infrared sources, sample and reference gas cells, detector, control
unit and amplifier, and recorder.  The reference cell contains a
nom'nfrared-absorbing gas while the sample cell is continuously flushed
with the sample atmosphere.  The detector consists of a two-compartment
gas cell (both filled with carbon monoxide under pressure) separated
by a diaphragm whose movement causes a change of electrical capacitance
in an external circuit, and ultimately, an amplified electrical signal
which is suitable for input to a servo-type recorder.
      During analyzer operation an optical chopper intermittently
exposes the reference and sample cells to the infrared sources.  At the
frequency imposed by the chopper, a constant amount of infrared energy
passes through the reference cell to one compartment of the detector
cell while a varying amount of infrared energy, inversely proportional
to the carbon monoxide concentration in the sample cell, reaches the
other detector cell compartment.  These unequal amounts of residual
infrared energy reaching the two compartments of the detector cell
cause unequal expansion of the detector gas.  This unequal expansion
causes variation in the detector cell diaphragm movement resulting in
the electrical signal described earlier.
      The output of this instrument is independent of sample flow rate.
A reduction in the resolution of rapid changes in concentration can be
r.ade by introducing additional volume in the sample line ahead of ,the
analyzer unit.
                                  52

-------

u
i_
Infi
So

ra
jr

red
ce


U
I
H*^ _^_^
Reference
  Cell
                      pp
                       O
                               Chopper
                        o!
jp
  O
 o
  o
                         fio
                       o
                        {
                      22
lo°
lo
|o
I  °
!°o
                      Sample
                       Cell
                                                    Sample In
                                                    Sample Out
              So'0^
              Signal
Recorder
                          o
         o
                        Control Unit
                                       d=.
                                           Absorbs I.R. Energy
                                           in Region of Interest
                                        O Other Molecules
  Figure 11.  Schematic diagram of a typical  nondispersive infrared
  CO monitor.
                              53

-------
      2.6.3.7   Reflectance and Transmittance.  Soiling.  The tape
sampler is used to measure suspended participates in ambient air.   Air
is drawn through a section of white filter paper.  The most generally
accepted sampling parameters for this measurement are:  a 1-inch
diameter spot, 7.07 fc/min (0.25 cu ft/min) flow rate and a two-hour
sampling period.  At the end of the sampling period, the tape advances
automatically by means of a timing mechanism, placing a clean section
of filter tape at the sampling port.  The collected spot is automatically
positioned under a photoelectric reflectance or transmittance head which
evaluates the density of the spot by measuring the light reflected from
or transmitted through the spot to the cell.  In general the greater the
amount of particulate matter filtered out of the air, the darker the
spot and the smaller the amount of light reflected or transmitted.  The
quantity of air sampled is expressed as linear feet and the final  result
reported in either of two units of measurement, the COH or the RUDS, per
1000 linear feet of air.  The units of 1000 linear feet can be
determined as follows:
      LF (units of 1000)          A  .
      where     LF is linear feet,
                Q  is sample air flow rate in cubic feet
                   per minute,
                t  is sampling time, minutes,
                A  is cross-sectional area of filter spot,
                   square feet.
      The COH   unit (coefficient of haze) can be defined as that ,
quantity of particulate matter which produces an optical density 6f
                                 54

-------
0.01 when measured by light transmittance in the region of 375 to 450
nanometers.  The transmittance of a clean filter is used as a reference
and is set at 0.0 density (or 100% transmittance).  The light trans-
mitted through the filter tape is expressed as follows:
                            U
      Optical density = log j— ,
      where     I0  is the initial intensity of transmitted light
                    through clean filter paper,
                I   is the transmittance observed through the soiled
                    filter paper.
              18
      The RUDS   (reflectance unit of dirt shade) can be defined as
that quantity of particulate matter which produces an optical reflectance
of 0.01 when measured by reflectance through a green filter.  The
reflectance of a clean filter paper is set at 100% on the reflectance
meter and is used as a reference.  The reflectance of light from the
filter tape is expressed as follows:
                                Ro
      Optical Reflectance   log ^-
      where     R0  is the initial intensity of reflected light
                    from "clean" filter tape
                R   is the reflectance observed from the soiled
                    filter tape.
      This RUDS unit is also expressed in terms of 1000 linear feet of
sample collected.  There is no general conversion factor which can be
used between the COM and RUDS units:  these measurements are depende.it
upon varying parameters such as the color of the particulates colU-.tyd,
their size distribution, depth of penetration in the filter tape, and
the variation of paper tape thickness.  There also is a general lack
                                 55

-------
of uniform correlation between tape  sampler measurements and high volume
                                    i
measurements.   Figure 12 is a diagram of a typical  tape sampler.
      Filter
      Paper
                       Sample Air
                          Inlet
 Timi ng
Mechani sm
                                      Pump Motor
    Figure 12.  Schematic diagram of a typical  tape sampler.
                                56

-------
      2.6.3.8   Nephelometry.  A common effect of participate air
pollution is the reduction of visibility.  Small particles suspended
in the air scatter light out of the line of vision, making distant
objects appear less distinct.  Visual range can be defined as that
distance at which the difference in contrast between the background
and the object being observed is too small to perceive.
      The air sample is drawn into the detection chamber where it ii
illuminated by a pulsed-flash lamp.  The scattered light is measured
over a range of scattering angles of 9° to 170° by means of a photo-
               19
multiplier tube   (See Figure 13).  The signal produced by the photo-
multiplier tube is averaged and compared with a reference voltage
from another phototube illuminated by the flash lamp.  Calibration
is performed by introducing clean filtered air and Freon 12 as
reference sources.  The amount of light scattering is proportional
to the mass concentration (ug/m ) of suspended particulates if the mass
and size distribution of the particles is assumed constant, a good
assumption owing to the inherent size-limitation constraints for
well-mixed, aged aerosols.
      Measurements of suspended particulates with this device afford the
user a continuous measurement in contrast with high volume sampling and
weighing techniques which are time consuming and provide after-the-fact
data.
      2.6.3.9   Chemiluminescence.  Chemiluminescent detection techniques
have been employed for the measurement of atmospheric ozone.  One
      ?fl
method   employs the reaction of Rhodamine B that is impregnated on
activated silica gel with ozone; the chemiluminescence produced is
                                 57

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                     Figure 13.   Schematic diagram of a typical  Integrating nephelometer.
en
oo
                  Air Sample
                     In
Flash Lamp
                                                Reference
                                                Phototube
                                  Electrdm c
                                   Control
                                   Module
                                                                                               To  Blower

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detected with a photomultiplier tube.  The recommended method21  as
described in the Federal Register, Vol. 30, No. 84, employs the gas-
phase reaction of ethylene and ozone; 21 the chemiluminescence is also
detected by means of a photomultiplier tube.  These specific ozone
chemiluminescent techniques were evaluated^ and were found
to be satisfactory as atmospheric ozone monitors.  The gas-phase
reaction is more advantageous for field use owing to its small size,
simplicity of construction, and ease of operation.  Figure 14 is a
typical diagram of the gas-phase ozone monitor.
      2.6.4   Compilation of Specific Monitors
      A compilation of pertinent information on continuous air quality
monitoring is presented in Appendix A.  This information was gathered
from the manufacturers' brochures and instrument manuals, product
information bulletins, advertisements in technical journals, plus
published and unpublished reports on instrument evaluation studies.
This compilation is intended as a preliminary guide to assist the user
in making an initial selection of two or three particular air quality
instruments which will fulfill his specific needs.  As noted previously,
a final selection should be made only after a comprehensive evaluation
is performed.
2.7   Installation of Monitors
      Consideration of the location of a continuous monitor with respect
to the remote station and other continuous monitors within the station
is necessary.  This should result in an optimum configuration whereby
the instrument performance and its ease of operation is maximized.  The
following factors should be considered.
                                 59

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               Samp!e  Air In
                 E E
                 E E
       Exhaust
       6  mm
         n,
6 mm
                                       Ethylene  In







,














..
—
—







•
\J







f
/






•- 1 0 mm
~ 6 mm
2 mm — \ k- 2 mm
« "
Photomul ti pi i er
Tube
Ol
X
o
i.
a.
o.

(
	 	 e
C
P
0
                                         Epoxy  Sealed
                                         Optically  Flat
                                         Pyrex  Window
                                         On End
                I  I  I  PI  I  IT I
High  Voltage
             Signal
Figure 14.   Schematic diagram of a typical gas-phase
           chemiluminescent ozone detector.
                       60

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      2.7.1   Monitor Location with Respect to Sample Manifold
      Minimum length of sample intake line from manifold to monitor
should be employed.  This presents no problem with the conventional
design since tiie manifold can be placed equidistant from all monitors.
However, with molecular diffusion design, some monitors will be located
at greater distances and in these cases the intake line will need to
be cleaned or replaced more frequently.  The sampling rate of the
specific monitor should also be considered.  Instrumentation requiring
the largest sampling rate should be placed near the exhaust end of the
sampling manifold.  Subsequent monitors should be placed, in decending
order of sampling rate, toward the inlet.  This factor becomes less
important with the use of conventional dynamic manifold which
incorporates a blower at the exhaust end.  It has no significance
when the molecular diffusion design manifold is used because of the
extremely large flow rate within this system.
      2.7.2  Monitor Location withRespect to Operationand Servicing
      Adequate space provisions for ease in operation and maintenance
are mandatory.  The amount of space required for each monitor will
depend on its specific physical dimensions and its ease of access.
If the equipment is to be rack mounted, ample room for a maintenance
man behind the rack is recommended.  Bench mounting requires more
linear space but provides the remote station with greater flexibility
since monitors can be removed or replaced with ease.  In both cases,
if the remote station is mobile, shock mounting is mandatory.
Commercially available, aircraft-type shock mounts are recommended
for this application.
                                61

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      2.7.3   Monitor Location with Respect to Power Requirements
      All Instruments and recorders should be powered by the regulated
voltage circuits within the remote station.  High current drain
equipment, such as pumps, heating baths, etcetera should be excluded
from the regulated circuits.
      2.7.4   Monitor Location with Respect to Reagent. Fuel, and
              Waste Requirements
      Equipment utilizing reagents, fuels, and waste provisions require
additional space considerations.  Reagent and waste storage containers
in many cases require as much room as the instruments themselves.  They
should be located to provide easy access by the operator.  In many cases
the reagents are light-sensitive and therefore must be protected from
light exposure.  This can be accomplished by storage below the bench,
within a cabinet.  Instrumentation requiring hydrogen as fuel should
be supplied by means of a hydrogen generator instead of storage
cylinders.  This is recommended from a safety standpoint.
2.8   Initial Startupof Mom toring Equj pment
      Prior to starting-up all continuous monitoring equipment, one
all-important prerequisite must be observed:  READ THE INSTRUMENT MANUAL.
The specific manufacturer's operational manual is a valuable source of
information; unless it is consulted, serious damage to the instrument
could occur.  These manuals generally provide detailed starting and
operating procedures which should be followed.  In addition, the
following subsystem checks are recommended.
      0   Electrical Grounding Check—Each instrument and its related
          accessories should share a common ground.  A continuity
          check with an ohmmeter can be used for this test.
                                 62

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      0   Gas Leak Check—All connections from pressurized  cylinders
          and/or hydrogen generators should be checked for  leakage.
          Use the soap bubble method for this test.
      0   Liquid Leak Check—Inspect all liquid reagent and waste
          connections for proper fit.  This check can be accomplished
          by visual observation.
      °   Flow Rate Checks—All gaseous and liquid flow measuring
          devices must be calibrated (see section 3.3).
      After the above checks are complete, and the instruments  are
operational in accordance with the specific instrument manuals,
dynamic calibration procedures should be performed.
      2.8.1   Preparation and Storage of Reagents
      The purity, stability, and shelf life of reagent supplies for use
with continuous monitors must be considered.  In most applications
recommended procedures for reagent preparation will  be supplied by the
manufacturer of the specific monitor.  In general, the use  of ACS
reagent grade chemicals and high purity deionized water (1  megohm  or
higher resistance) is required.  Reagents whose slight variation in
purity would have an effect on the sensitivity of the method—organic
dyes for example—should be purchased from a single lot in  a quantity
sufficient for at least one year of operation.  Light-sensitive reagents
should be stored in appropriate containers.  Standard gas mixtures for
zero and span calibration should be purchased from a supplier who  has
the laboratory capabilities to provide gaseous calibration  to a
tolerance of +2%.  One such supplier is Scott Research Laboratories.
                                 63

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A reference supply of these gases should be maintained for cross-
reference with all future standard gases to insure continuity.
      Often the stability of reagents is affected by fungus growth;
                                                                 23
to avoid this problem the addition of a fungicide is recommended.
The most effective fungicide found for Saltzman reagent, acid peroxide
reagent, and neutral buffered KI reagent is Dowicide G.
      Representatives of the Dow Chemical Company have recommended
the use of Dowicide B and G used together to control slime, fungi,
algae and corrosion in industrial process waters.  Dowicide B and G
together at a concentration of 10 ppm each should give adequate
protection against fungus growth in the Saltzman reagents, peroxide,
and neutral KI without affecting their chemical functions.
                                 64

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3.0   CALIBRATION
3.1   Role of Calibration in Air Quality Monitoring
      The ace racy and validity of the data derived from air monitoring
instrumentation are dependent upon the type and extent of quality control
procedures employed.  The first element of data quality control  is
instrument calibration.  Calibration determines the relationship between
the observed and true values of the variable being measured.  Instrument
calibration provides maximum quality control in collection of reliable
data and is the key to comparison and utilization of data being produced
by Federal, State, local, or even private air sampling networks.
      Most present-day monitoring instrument systems are subject to
drift and variation in internal parameters, and cannot be expected to
maintain accurate calibration over long periods of time.  Therefore,
it is necessary to check and standardize operating parameters on a
periodic basis.  These are predetermined by the manufacturer and are
usually listed in the operator's manual.  Direct, dynamic calibration
utilizing the pollutant species monitored is most desirable, although
pseudo-calibrations (static) may be carried out using a material having
the same effect on the sensor as the pollutant of interest.
      In many instances, static calibration tests are desirable since
they provide a simple, rapid means of obtaining operational data on
specific components of the system^  These tests are normally employed
on a frequent basis, in some cases, daily.  Dynamic calibration serves
the purpose of establishing the actual interrelationships between the
gaseous sample and the data output.  Thus, it provides the evidence
that all components of the continuous monitor are functioning
                                  65

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properly to yield valid, reproducible results.  Initially, frequent
dynamic calibrations (e.g., once per week) will be required to establish
some degree of conf". Jence.  Once this instrumental confidence is
established, dynamic calibration is normally performed on a less
frequent basis, perhaps monthly or quarterly depending on the specific
instruments prior performance.
3.2   Dynamic Calibration
      Simply stated, dynamic calibration involves the introduction of
gas samples of known composition to an instrument for the purpose of
producing a calibration curve or adjusting the instrument to a
predetermined curve.  This curve is derived from the instrumental
response obtained by introducing several successive samples of different
known concentrations.   These standard gas mixtures are introduced in an
increasing order of concentration to avoid contamination of the inlet
lines and to minimize response times.  The number of reference points
necessary to define this relationship will depend on the nature of the
instrument output.  For an instrument with a linear output, a zero
reference point, and two levels, approximately 30% to 90% span would be
sufficient to define the instrumental performance.  For nonlinear
instrumentation, several more points, in some cases as many as five,
will be required to adequately define the response characteristics.   To
insure that a negative drift does not go undetected, the zero should be
set at 5% scale.  Initially, dynamic calibration methods were primarily
considered for laboratory application where mobility is not an important
factor.  Recent developments employing standardized permeation tubes
                                  66

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and portable dilution apparatus have led to field  application  of
dynamic calibration.
      3.2.1   Permeation Tubes
      A permeation tube consists of a liquefied material  contained
under its own vapor pressure, in a sealed section  of permeable
fluorinated ethylene propylene (FEP Teflon) tubing.   The  gradual
permeation of the enclosed material through the FEP Teflon tubing
permits the dispensing of microgram quantities of  that material.
Following a "conditioning'1 period of a few hours to several weeks,
permeation proceeds at a highly constant rate until the enclosed
material is nearly exhausted.  The rate of permeation is  highly
temperature dependent, but is independent of normal changes in pressure
and composition of the atmosphere.
      To prepare specific permeation tubes for use in calibration of
$0)2 and N02 monitors, pure liquid SC^ or NOo is contained in a tube of
FEP Teflon and sealed at the ends with Teflon plugs.  The plugs are
held in place by flanging a small piece of stainless steel on Teflon
over the plug with a swaging tool.  Figure 15 is a diagram of a
permeation tube.
      The tubing is selected with diameter and length such that the permea-
tion rate of the gas that it contains 1s In the desired range.  The permea-
tion rate can be determined gravimetrically over a reasonable  period of time
to at least three significant figures.   Techniques used in making the permea
tion tubes and charging them with gas are "described by O'Keefe and Ortman.24
      Calibration of a liquid-filled tube consists of collecting weight
data losses over a period of approximately six weeks.  Between
                                  67

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              Figure 15.  Permeation tube,
       Teflon Tube
Retaining Ring

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weighings, the tube must be maintained at a controlled temperature
slightly above ambient, usually 25 j^O.rC, and low humidity using
silica gel or a comparable desiccant.  Weight losses per unit of time
are expressed as permeation rates.25'26  Calibrated permeation tubes
are commercially available from Metronics Associates, Inc., and
Analytical Instrument Development Co.; and certified SO- tubes are
available from the National Bureau of Standards.
      The following equation permits calculating parts per million
(V/V) pollutant in a gas flowing over a tube as a function of air flow
rate:
                            C -
PR   MV
-NT* T
where
      C  is  ppm (V/V) pollutant transferred to a
             gas flowing over the tube.
      PR is  Permeation rate at 25°C in micrograms/min.
      M  is  Molecular weight.
      MV is  Molecular volume at 25°C (24.45).
      L  is  Air flow in liters/min.
      An example involving the use of this calculation is as
follows:
      Given:  Permeation rate of S02 tube at 25.0°C   2.20 yg/min
      Total dilution air = 5.20 1/min.
      Find:  Concentration of standard  gas mixture
                                 69

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      Note:  If the permeation tube temperature employed is not
25.0°C, an appropriate correction factor'can be applied as presented
in Table C-3 in Appendix C.  This table was generated for S(>2
permeation tubes on y and if it is to be used for other tubes, its
applicability should be determined first.
      3.2.1.1  Permeation Tube Dilution Apparatus.  Figure 16
illustrates an apparatus for producing controlled low level concentra-
tions of standard gas mixtures employing permeation tubes.  The system
employs a gravimetrically calibrated permeation tube and purified air
as a diluent.
      The diluent gas is prepurified cylinder or ambient air from
which pollutants and moisture have been removed by passing through
scrubbing columns filled with 8- to 12- mesh activated charcoal and a
desiccant.
      The diluent air is passed through a needle valve and a precision
rotameter, calibrated within + 155 by a wet-test meter, to control and
measure the flow.  A purge flow of purified air (approximately 0.5 1/min.)
is passed through the temperature conditioning coil and over the
permeation tube, which is held in a Pyrex glass holder, submerged in a
water bath, and controlled to 25 +_ .1°C.  The diluent air and the
purge gas stream are mixed in the mixing bulb.  The resultant pollutant
concentration is varied by adjusting the needle valve to control the
air stream flow rate.  A vented Pyrex manifold distributes this
concentration to the instrument at atmospheric pressure.  All surfaces
in the distribution system that contact the test atmosphere must be
made of Teflon or Pyrex glass.
                                 70

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              Flowmeter
                  r-Permeation
                  \    Tube
     Mi xi ng
      Bulb
        Sampli ng
         System
Excess
                       Dryer
                       Column
                   Air
                   Cylinder
Valve
   Charcoal
    Column

Thermometer
                                                                           Oilless
                                                                              Pump
                                Dryer
                                Column
                    Water
                    Pump
                                   Constant Temp. Bath  (+  0.1QQC)
                                                                            Flow
                                                                            Meter
                      Figure  16.  Permeation tube dilution apparatus.

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      A portable calibration apparatus has been developed for field
application.  A schematic diagram of this apparatus is shown in
Figure 17.  The apparatus was designed specifically for portability;
therefore, since it does not include a thermostatically controlled
water bath, it does not permit unattended operation.  The general
specification, construction details and use of this apparatus have
                        27
been described by Rodes.    This system can be built with technician-
level personnel at a cost of approximately $800.  Commercially available
calibration systems are available from Tracer. Inc., and Analytical
Instrument Development Co.
      3.2.2   Standard Gases
      Mixtures of stable gases can be prepared to exact concentrations
in pressurized cylinders.  Following a confirmatory analysis by a
referee laboratory, they can be used as standard calibration gases.
Commercially available mixtures of methane in air or nitrogen and
mixtures of carbon monoxide in helium or nitrogen have been found to
be very stable over periods of several months.  Span calibration of
carbon monoxide and hydrocarbon monitors is achieved by direct
introduction of these standard gases to the monitors.  Normally a
manifold arrangement, such as shown in Figure 18, is employed to maintain
the appropriate sampling conditions.
      Preparation of cylinder-stored standards of the more reactive
gas mixtures such as sulfur dioxide or nitrogen dioxide in air cannot
be achieved since these gases are unstable at the required concentrations.
Higher concentrations of S02 or N02, in the 0.5 percent range, have
been found to be stable for several months providing inert diluent
                                 72

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                                                  Flowmeter
•vl
OJ
                                   Filter
                   Muffler
         Vent
         Valve
                                                                 Permeati on
                                                                 Tube Holder
                                                                                             Vent
                                                                                             Vent
                                                                                    To
                                                                                    Instruments
                                                                            Thermistor
                                                                            Temperature
                                                                            Moni tor
                          Figure 17.   Portable calibration apparatus for use
                                     with permeation tubes.

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                              To  Instruments
               Regu1ator
il
          	fc*3h
                         •Flowmeter

                                 Mani fold
         Needle Valve
           Standardized
           Gas Mixture
                                                     Vent
Figure 18.  Distribution system for use with standard gases.
                     74

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gas and clean storage cylinders  are  used.   Mixtures of these gases
can be diluted to lower calibration  levels  by means of a  dilution  board
device.28'29
      The N02 or S02 dilution board  used  for dynamic  referee analysis
(Figure 19) combines a simple flow proportioning  system with a  mixing
chamber and a self-contained sampling train for manual sampling and
analysis.  The gas proportioning system has two inlet connections:
one for a concentrated gas mixture (prepared and  transported  in a
stainless steel cylinder) and the other for diluent air  supplied by
a pump, preceded by columns containing activated  carbon  and soda lime
to remove impurities.  Each component gas flows through  a needle valve
and rotameter before the two are combined in a  mixing chamber.   The
diluted mixture then passes simultaneously to  the manual  sampling
system and to the analyzer being calibrated.   A series  of concentrations
of the calibration gas can be produced by varying the flow ratios.  As
long as the two flowrates are kept constant, the produced mixture is
uniform.  Fritted glass bubblers are used for collection of NC^, while
standard impingers are used for S02-
      The ozone calibration apparatus differs  from the one described
above in that it uses an ozonizer    (see Figure 20),  which consists of
an eight-inch pencil type mercury lamp which irradiates a 5/8  inch
quartz tube through which clean air  flows at 5-10 liters/min.   The
generation of ozone may be varied from 0-1 ppm by variable shielding
of the lamp envelope.  The flowrate  is controlled by a needle  valve
and measured by a  rotameter.  The ozonized air passes to a manifold
                                  75

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on
               Flowmeter



               Valve


             ORegul ator
       Concentrated
       Standard  Gas
                                                         Instrument      Referee

                                                             |              t           Excess
              Mixing Bulb
imFlowmeter
                               Charcoal
                                Column
               Drying
               Column
                     Oilless Pump
                                                                           Room Air
                                 Figure 19.  Dilution board device.

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Air
      6-in. Pen-Ray
          Lamp
              J

  Alumi num
Box Enclosure
                      Adjustable   _
                        Sleeve      \
                                  1 I
                                                •Collar
                      Quartz Tube, 	/
                      15-mm O.D.
                                           s
                     Ozone Source
J Flow
af-(o-io
_|<
k Needl
y
Meter
1 i ters/mi n)
e Valve
Micron Fi Her
")
Rn-Regi
ilator ^_ —


5 li
Ozone
Source

Sampl e
,', A ,(,
Manifold U


                           Vent
               Cylinder
                 Air
       Figure 20.  Ozone source, dilution, and manifold system.
                              77

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 from which the monitor under test draws its sample.  Standard impincers
 are used to sample the test atmosphere.  A certified ozone generator
 is available from the National Bureau of Standards.
      Wet chemical analysis of the sample collected simultaneously in
 the manual buboler provides data for the preparation of the calibration
 curve,  Methods which can be used for the preparation of calibration
                                                                     01 00
 curves for S02 and N02 are published by the Health Laboratory Service  '
while the calibration methods for oxidant is included in the reference
method for photochemical oxidants published by the Environmental
 Protection Agency.
      Another method of dynamic calibration commonly used prior to the
advent of the permeation tube employs standard gas mixtures prepared
                                                33
and contained in inert, impervious plastic bags.    Polymeric plastic
films such as Teflon, Mylar, Tedlar, Scotchpak, Kel-F, Saran and
cellophane have been used for this application.  Of these materials,
Teflon, Mylar, and Tedlar have been found to be the most desirable
for overall applications.
      Gas mixtures are prepared in bags by metering a large volume of
diluent gas into the bag and then injecting a small amount of
concentrated gas from a syringe through a serum stopper attached to the
inlet fitting.  Mixing is accomplished by kneading the bag.  Condition-
ing of the bag for several hours with the same magnitude of
concentration of pollutant prior to its use is necessary to avoid
losses through adsorption on the walls of the bag.
      If the volumes of diluent and sample gases have been accurately
measured, and if the mixtures are stable for the particular gas
                                  78

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rr.-.xcure-bag co.r.bination selected, the standard can be assumed to
contain its calculatec concentration.  Practically, the concentration
snould be verified by a referee wet chemical  method.
3.3   Calibration of Flow Parameters
      Most automatic monitors have gaseous flow systems which must be
maintained at a fixed rate for optimum operation.  These systems must
be maintained, calibrated, and adjusted to the manufacturers' recommended
specifications to provide accurate service.  Two methods for gas flow
calibration are in general laboratory use:  primary calibration using a
wet test meter and secondary calibration using a precalibrated mass
flowmeter.  The use of the mass flowmeter results in more rapid
measurements, but it is subject to instrumental drift and should be
periodically checked with a wet test meter.  All other flowmetering
devices such as rotameters should be checked against a wet test meter.
Another more rapid approach to insuring the performance of mass
flowmeters in routine usage is to reserve one calibrated mass flowmeter
at the central laboratory as a reference and check the field meters
against it before using.  The test meter is placed upstream to the
instrument's intake system in order to maintain atmospheric pressure
through the device.  Several data points (at least 5) are obtained by
varying the control valve on the instrument.  The volumetric flow data
is plotted on linear graph paper against the rotameter setting to
obtain a flow rate calibration curve.  A typical rotameter calibration
data sheet is presented in Figure 21.  A typical flow rate calibration
curve is presented in Figure 22.
                                  79

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Instrument
Rotameter Serial No.
Calibrated With 	
Location
Temperature
Atmospheric Pressure	mmHg
Relative Humidity	%
Calibrated By 	
Test           Rotameter       Total        Time        Flow rate
Point          Reading        Flow (1)      min.         (1/min.)
1
10
             Figure 21.  Rotameter calibration data sheet.
                                  80

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           300
           250
_£

en
           200
o>
      
-------
      Liquid flow calibration is achieved by means of the volumetric
displacement technique.  This method consists of measuring the volume
of liquid displaced by the reagent pump over a prescribed and measured
unit of time.  Often the reagent transfer plumbing must be disconnected
at a point beyond the liquid flow rotameter, preferrably in the waste
line, and directed into a graduated cylinder.  Care must be exercised
to insure that the pressure head remains constant.  Calibration curves
for liquid flow systems are unnecessary if the instrument is equipped
with a fixed-rate solution pump.  Instruments with an adjustable
solution metering pump, liquid rotameter, and flow control system should
be calibrated throughout their operational range.
      The flow parameters must be calibrated and adjusted to the
prescribed settings prior to dynamic calibration.  Once these variables
are fixed they should be recorded on the front panel of the continuous
monitor for ready reference during the periodic operational checks
described in section 4.0.
3.4   Static Response Checks
      Modified calibration methods are applied under static instrumental
conditions to check instrumental response.  Normally, no sample air
flow is permitted when utilizing these techniques.  The reagent flow
system is sometimes activated to introduce the test solution into the
detector.  Static methods, if used on a routine basis, provide a rapid
means to determine instrumental  operational response.  These data,
when compared to previously obtained values, provide a good indication
when maintenance and dynamic calibration procedures are necessary.  In
general static methods have found wide usage as a rapid standardization
                                  82

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check employing a single reference point, since a minimum of eqoiorent,
time, and skill are required.
      3.4,1   Static Chemical Methods
      A widely used method of static response employs standard solutions
which are chemically equivalent to the pollutant.  In this procedure,
dilutions of a standard solution are introduced into the measuring cell
of the analyzer.  A calibration curve can be plotted from points
obtained by comparing the instrument response with the equivalent
pollutant concentration.
      A similar static method employs standard solutions such as dyes
and electrolytes which are not necessarily chemically equivalent to
the reacted reagent, but which reproduce its measured property, such as
optical density or electrical conductivity.  Such solutions are useful
only when their pollutant equivalents have been determined on a properly
calibrated instrument.
      3.4.2   Static Electrical Methods
      Because so many types of circuitry are employed in the detector
section of continuous monitoring instruments, it is necessary to use
caution when employing static electrical checks on these systems.  The
manufacturer's manual should be consulted as to the type of signal
provided, i.e., current, voltage, or resistance.  In most cases
electrical signals can be simulated with commercially available test
equipment.  This mode of static electrical calibration serves the
purpose of standardizing the various electronic and recording systems
associated with the continuous monitor.
                                  83

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3,b   Dynamic Response Checks
      The response of many continuous monitors—such as those for the
determination of hydrocarbons, sulfur dioxide, nitrogen dioxide,  and
oxidants~can be dynamically checked by relatively simple means.
Output from an ultraviolet light source could be used for all  oxidant
instruments, while the appropriate permeation tube—SOgt N02i  and
butane (for hydrocarbons) can be used to check the response  from  the
corresponding instrument.  This technique is recommended only as  a
rapid dynamic response check, since errors can result from background
levels of pollutants in the ambient air used as the diluent  gas,  and
from the fluctuations in the temperature and moisture control  of  the
permeation tube.
                                 84

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4.0   OPERATION
4.1   Operational Performance Log—Check Lists
      Often problems encountered during operation of atmospheric
analyzers are slow in developing and therefore go undetected for some
time.  These minor malfunctions cause inaccurate readings and eventually
lead to instrument downtime unless a routine method of instrument
checking and performance logging is established to identify them before
they become severe.  Thus, an organized procedure of operational logging
and instrument checking must be established to define the chemical,
physical, and electronic operational parameters on a continuing basis.
It is highly recommended that the operational history of each specific
monitor be routinely recorded, preferrably in individual logs.  These
performance logs should be designed in a standardized format to insure
uniformity in recording all system checks, maintenance requirements,
maintenance schedule, calibration data, and all other pertinent
information.  A concise historical record of these parameters can be
attained provided that the log book is properly organized.  One approach
is to record these functions with reference to a predetermined
operational period.  Each operational period would occupy a separate
section within the log book, e.g., daily, weekly, monthly, quarterly,
etc.  The specific information to be logged in each section would be
dependent upon the operational characteristics of each individual
instrument.  This specific information can be developed from the
manufacturer's instrument manual.  However, for any monitor, general
information can be defined with respect to the operational periods
as follows:
                                 85

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(a)  Daily operational log requirements
  0  Instrument settings—All pertinent instrument settings,
     such as operational function switches, gain and zero-
     adjustment knobs, etc., should be included.
  0  Visual inspection of the past 10 to 30 hours of strip
     chart data.
  0  Flow parameters—Liquid and gaseous flow rates should
     be verified.
  0  Peripheral support items—Supplies such as reagents,  fuels,
     recorder paper and ink, waste reservoirs, etc., should be
     inspected.
  0  Zero drift measurements—Zero measurements should be
     included.
  0  Span drift measurements—Span measurements should be
     included.
  0  Static operational checks—Static checks to verify the
     operation  of  the various components of the total  system
     should be  employed.
  0  Specific routine maintenance—Maintenance schedules for
     daily use  should be developed from the manufacturer's
     instrument manual and regularly employed.
(b)  Weekly operational log requirements
  0  Peripheral support items—Same requirements as above.
  0  Span measurements—Single-point dynamic span checks are
     recommended.
                         86

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       0  Specific routine maintenance—Maintenance  schedules for
          weekly use should be developed  from the  manufacturer's
          instrument manual and employed.
     (c)  Monthly operational  log requirements
       0  Peripheral support items—Same  requirements  as  above.
       0  Specific routine maintenance—Maintenance  scheduled for
          monthly use should be developed from the manufacturer's
          instrument manual and employed.
     (d)  Quarterly operational log requirements
       0  Specific routine maintenance—Maintenance  schedules for
          quarterly use should be developed from the manufacturer's
          instrument manual and employed.
       0  Calibration—Full range dynamic calibration  procedures
          should be developed from section 3 and employed quarterly.
     In order to illustrate this systematic approach,  the following series
of operational log forms (Figures 23, 24,  25, and  26)  have been developed
for use with a conductivity monitor for S02, although  this type instrument
is not a recommended method.   In  addition to the  routine operational
sections, a final section cataloging major maintenance and parts
replacement is suggested.  With this  information  a  fatigue sequence
or failure rate of  components  can  be  established.   Future requirements
for maintenance can be predicted  and  scheduled thus avoiding instrument
downtime.
4.2   Data Logging
      4.2.1   Role of Data Logging
      The voltage output from  a continuous  analyzer must be input to  a
data logger in order to obtain a  usable record of the ambient

                                 87

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Date 	  Time	  Operator	
Instrument Ident.      	  	  Zero Set at
Station Ident. 	.	  Instrument Range	
Air Flow Set at	1/min.
Reagent Flow Set at	ml/min.
                            CHECK LIST

[  ] Check operational settings.
[  ] Check system for leaks—air and liquid.
[  ] Check recorder for "live trace" and time synchronization.
[  ] Check reagent supply.
[  ] Check waste reservoir.
[  ] Check recorder supplies (paper and ink).
     Air flow rate found at	1/min.   Set to	1/min.
     Zero check	%.  Shart set to	% chart.
     Record of electrical static check	ohms =	%  chart.
     Remarks and/or actions required to rectify unsatisfactory
     conditions:
Figure 23.   Daily operational  log (conductivity monitor).
                                88

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Date 	  Time 	  Operator	
Instrument Ident.  	  Station Ident.

                           CHECK LIST

[  ] Replenish reagent supply.
[  ] Empty waste reservoir.
[  ] Remove recorder chart and process data.
[  ] Check solution pump rate.
     Dial setting	  Flow Rate	ml/min.
     Remarks and/or actions required to rectify unsatisfactory
     conditions.
Figure 24.  Weekly operational log (conductivity monitor).
                                 89

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Date	 Time	  Operator	
Instrument  Ident. 	  Station Ident.

                           CHECK LIST

[  ] Remove and clean inlet sample tubing.
[  ] Remove and clean reagent tubing if necessary.
[  ] Remove and clean rotameter if necessary.
[  ] Tighten all fittings if necessary.
[  ] Change absorbent in zero scrub column.
[  ] Oil liquid and air pumps.
     Remarks and/or actions required to rectify unsatisfactory condi-
     tions:
Figure 25.  Monthly operational  log (conductivity monitor).
                                 90

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Date	  Time 	  Operator	
Instrument Ident. 	   	   Station Ident.
                           CHECK LIST
[  ] Electronic check of recorder zero and fullscale response.
[  ] Clean reagent reservoir.
[  ] Clean and flush conductivity cell.
[  ] Clean and calibrate sample rotameter.
[  ] Clean and flush contact column.
[  ] Clean sample manifold.
[  ] Replace carbon vanes in air pump.
[  ] Change vibration pads on air pump.
[  ] Replace solution pump with a refurbished unit.
          Dial Setting 	  Flow Rate 	ml/min.
     Dynamic calibration
     Concentration ppm                  Response % Chart
     Remarks and/or actions, required to rectify unsatisfactory
     conditions.
Figure 26.  Quarterly operational log (conductivity monitor).
                                91

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concentrations of a pollutant.  Typical data logging systoms employ strip
chart, punched paper tape and magnetic tape recorders.  As indicated
earlier in the manual, the SAROAD system has been designed to facilitate
the transference of strip chart data to hand recorded forms and from
these to punch cards.  A guideline manual has been generated to detail
                            •% *
this step-by-step procedure.    Data loggers may be located at the
field sampling station, at a central command station or a combination of
both.  Some recently installed systems transmit data from the remote
sensor via telephone lines directly to a computer.  This computer system
could be either a small computer dedicated to the support of the
continuous monitoring system or a large general purpose computer used
in a time-sharing mode.  For this application a large general purpose
computer is not a good idea.  Generally the priority of the continuous
recording might get displaced, preventive maintenance downtime destroys
required data, and the continual program shifting may destroy the
systems operation.  A small dedicated computer is better suited for
this type of operation.
      4.2.2   Logging Pollutant Level
      The voltage output from a continuous analyzer can be recorded in
a variety of ways.  A description of three currently used techniques
is given below.
      4.2.2.1   Continuous.  A continuous trace of the output signal
can be recorded on a strip chart.  The deflection of the pen on the
strip chart can then be related to the ambient concentrations of the
pollutant through either a linear or nonlinear function by means of a
calibration curve.  The continuous trace provides a visual record of
                                 92

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 the  pollutant concentration  fluctuation over a specified tine perioa.
 Peak pollutant concentrations  as well as time averaged concentrations
 can  be read from the  strip chart.
       4.2.2.2   Instantaneous.  Another way to record the output from
 the  sensor is to pick up  the instantaneous signal at precise increments
 of time.   The voltage is  digitized by an analog-to-digital converter
 and  recorded on punched paper  or magnetic tape.  Because of short time
 fluctuations in ambient concentrations as well as background noise in
 the  system,  it is advisable  to record instantaneous values at time
 intervals  of 5 minutes or less.
       4.2.2.3   Time  Averaged.  The high frequency fluctuations in the
 sensor signal,  caused by  background noise and short term variations in
 concentrations,  can be filtered out by including an electronic integrator
 in the data  logging system.  The integration period can be varied from
 a few  seconds  to perhaps  an  hour.  In order to provide some information
 about  short  term pollutant concentrations, integration times of 15
minutes or less  are advisable.  The integration method works only for
 linear output  signals.  Integrating a nonlinear response is invalid.
       4.2.3    Data Reduction and Validation
       The record produced by the data logging system  requires reduction
and processing  to obtain  pollutant concentrations in appropriate units.
Experience has  also shown that operational  difficulties may result in
the production of invalid data from continuous analyzers.   Thus data
validation is an extremely important part of data processing activities.
Methods of handling air quality data ranging from manual  to fully
automated are discussed below.
                                  93

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      4.2.3.1   Manual.  Measurements of pollutant concentrations
recorded on strip charts must be reduced to a set of discrete values.
This reduction is a manual operation requiring an individual to scan
the entire strip cha'r. to determine the appropriate time-averaged
concentrations.  Typically, hourly average and daily peak concentrations
are read from the chart.  The daily peak concentration is usually taken
to be the maximum 3 to 5 minute concentration for the day.  Oetermining
average concentrations by visually averaging the trace over a given time
period is admittedly subjective; however, experience has shown that
individuals who read charts in a routine basis become quite adept and
can in fact determine the average within the limits of accuracy of the
sensor system.
      Concentration data obtained from reading strip charts can be
recorded for further use in two ways, (1) on preprinted forms by hand,
and (2) on punched charts by means of a chart reader coupled with a
key punch.  The SAROAD format being used for hand recording hourly and
24-hour data is presented in Figures 27 and 28.3 Usually, hand recorded
data are transferred to punched cards for subsequent report preparation
and statistical analysis.
      Since the reduction of data from strip charts, either manually or
with the aid of a chart reader, is a very tedious task, it should be
performed by trained clerical personnel.  In order to maintain high
quality data reduction, it is good practice to have strip charts edited
by a skilled technician or even technical personnel who are familiar
with the operation of the sensor.  Through the editing process, comments
necessary to correct individual readings can be entered on the ehart.
                                  94

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       Less than 24-hour sampling interval
       m—
                      Agency
                     City Name
ENVIRONMENTAL PROTECTION AGENCV
   National Aeromewic Oala Bank
 Research Triangle Park. N. C. 27711

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-------
                                 ENVIRONMENTAL PROTECTION AGENCY
                                    National Aerometric Data Bank
                                  Research Triangle Park. N. C. Z7711

                                      SAROAD Daily Data Form
24-hour or greater sampling interval
                                                            State
                                OMB No. 158-R0012
                                Approval expires 6/30/76


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                                            96

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Such important things as current instrument zero and span  drift
corrections, and periods of invalid data can be so indicated.
      The data record on the strip chart is shown as a trace  on  a  0-100
percent scale.  In order to facilitate the conversion to concentration
units, it is customary to provide templates which can be superimposed
on the strip chart.
      The throughput of an individual who reduces data from a strip
chart can be significantly increased through the use of an automated
chart reader.  In using the chart reader the strip chart is advanced
over a light table.  The operator aligns the horizontal (time) and
vertical (concentrations) scales appropriately on the strip chart.  By
depressing the read switch, the data is automatically recorded on  a
hand copy through an electric typewriter or on punched cards  through
a key punch (or both).
      4.2.3.2   Semi automated System.  A semiautomated data logging
system is defined as one in which either paper or magnetic tape devices
are used to initially record the digital output from the sensor.  The
recording device may be located either at the field sampling  station or
at a central station.  In either system a new dimension is added to the
problem of data reduction and validation.  Data stored on tape (paper
or magnetic) provides no information about ambient pollutant
concentrations until a listing is prepared by the computer.  If the
tape recording device is located at the field station, the tapes must
be physically transported to the computer center.  This is usually done
once or perhaps twice each week.  Even when a telemetry system is  used
and data is stored on tape, there is no direct interface to the computer
                                  97

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and as a result data tapes are batch processed.   Such resulcs are
generally available in tabular form within 24 hours or less.
      In order to properly recognize that a continuous monitor is not
performing satisfactorily, it is necessary to observe the output data
immediately.  Thus, the remote station must be equipped with  either
a strip chart recorder or an electronic digital  readout device.   Even
telemetry systems usually employ a teletypewriter to obtain an
immediate printout of the transmitted data.
      Data logging systems must always incorporate the necessary means
to uniquely identify data as to location of sampling station, date and
time of sample collection, and the pollutant being measured.   In
addition they should provide a means of identifying periods when the
sensor is operating in a calibration mode as well as the calibration
results.  Likewise there is usually a mechanism by which the  operator
can insert "no-data" codes if the sensor is being serviced or is
malfunctioning.  An additional requirement to include in the  system
design is an external mechanism to instruct the computer to make changes
or deletions of data when it is determined, after the fact, that
invalid data were recorded on the tape.  This is an item of concern
since continuous monitoring instruments occasionally drift (or even
fail) when permitted to operate unattended.  A single erroneous  reading
can substantially alter an hourly or even daily average pollutant
concentration.  One way to accomplish this correction is through an
operator's log which can be transferred to punched cards and  read into
the computer at the time of data processing (Figure 29).
                                  98

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to
10
                SEC 468
               (REV 10-61)
RECORD OF OPERATOR'S LOG
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                                                 Figure 29.  Operator's log.

-------
       The initial  step in data processing by the computer  involves  tie
                                                                  2
 conversion of the  sensor output to pollutant concentrations  (ug/m  or
 ppm).  At this point the computer makes  the necessary adjustments for
 instrument calibration and deletes data  known or identified  as  being
 invalid.   The computer can also be programmed to make zero and  span
 drift corrections.   Prior to preparing an initial  output listing  of
 the basic measurement data,  it is possible to have the computer perform
 a first order validation of the data.  The criteria for such- validation
 can include among  other things a maximum pollutant concentration
 which is  unlikely  to be exceeded at a given sampling location,  or a
 maximum difference  between successive concentrations which is unlikely
 to be exceeded.
       Data validation criteria should be tailored to the air quality
 experience of a  given area.   Typical values which could be used for
 maximum concentrations not to be exceeded for 5-minute instantaneous
                              3                         3
 readings  are:   S02, 2618 pg/m  (1.0 ppm); C02>  57.2 mg/m   (50 ppm);
 N02, 940  pg/m3 (0.5 ppm); total  oxidant, 490 pg/m3 (0.25 ppm);  and  total
 hydrocarbons,  9.8 mg/m  (15 ppm).  Similarly, a reasonable criteria
 for questioning  the difference in concentration between successive
 5-minute  values  would be when such difference is more than 20 percent
 of the above maximum.
       Any pollutant concentration which  fails to meet the  criteria  is
 shown on  the output listing along with an appropriate symbol to identify
 the possible reason for being invalid.   The final  determination as  to
'the validity of  data must be made by an  individial  who is  knowledgeable
 about the location  and tne operation of  the sensor.
                                 100

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      After the data have been validated, it is again necessary to
have an external means of communicating the appropriate information
to the computer.  An example of recording forms from which punched
cards can be prepared was presented in Figures 27 and 28.
      4.2.3.3   Computer Controlled System.  A network of continuous
monitoring stations can be operated under the control of an on-line
computer located at a central facility.  In this system the computer
is programmed to sequentially interrogate the remote stations at some
predetermined interval.  When a remote station receives a command to
transmit, a scanning device interrogates each sensor  and assembles
the information into a message which is then transmitted to the
receiver at the central station where it is immediately input to the
computer.  When the computer reads the end-of-message, it signals the
next station, or if all stations have been interrogated, waits for
the beginning of the next cycle.
      The on-line control unit at the central station may be either a
small computer totally dedicated to functioning as a control module or
a time-shared general purpose computer.  When a small computer is used
as the control module, it is still necessary to have access to a
general-purpose computer.  This computer is used to maintain historical
files, prepare routine reports, and perform retrospective statistical
analyses.
      The decision as to the type of computer to be used as the control
module is determined to a large extent by the way in which the signal
from the remote sensor is presented to the telemetry system for
transmission.  The signal output from most sensors is an analog voltage.
                                 101

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If the transmission distance is more than a few miles, or if there are
several sensors at a remote station, it is necessary to convert the
signal to a digital voltage.  There are two ways of handling the
conversion:  (1) the instantaneous analog voltage may be converted to
digital at short time intervals (e.g., each minute), or (2) the
analog signal may be input to an electronic integrator and the output
from the integrator converted to digital.
      When instantaneous sensor outputs are transmitted to the central
station, the on-line computer accumulates the values for each sensor
over an interval of time (usually one hour or less) and computes a
time-averaged pollutant concentration.  The average concentrations are
then printed to obtain a hard copy which provides a continuing record
of air quality.  The on-line computer can be used to calculate running-
average concentrations (e.g., 6 hrs., 12 hrs., 24 hrs., etc.).  When
the basic time-averaged concentrations are calculated, they are also
written on computer-compatible magnetic tape.  This tape is processed
by the large general-purpose computer to update the master data files.
If the sensor output is integrated prior to transmission of the central
station, the computer is required to poll the remote station much less
frequently.
      A computer-controlled system must contain provisions for
validity checks on the data.  Errors of transmission are usually
identified by parity checks.  A more serious problem occurs when the
sensor is malfunctioning and produces an output signal that is not
representative of the ambient concentration of the pollutant.  It is
possible to program the computer to validate incoming data.  As each1
                                102

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pollutant concentration is calculated by the computer,  it can  be
checked against some maximum concentration which is unlikely to be
exceeded.  If the maximum is exceeded, the calculated value can be
tagged with an appropriate symbol on the ouput listing.   Secondly,
successive pollutant concentrations can be compared and,  if there is  a
•arge difference, the most recent value can be tagged with an
appropriate symbol.  It is then necessary for someone to  determine
whether or not the computed concentrations are valid.  Obviously, if
a value is determined to be invalid, it must be deleted or changed in
the master data file.
                                 103

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5.0   MAINTENANCE
5.1   Role of Maintenance
      Maintenance requirements for automatic monitoring equipment can
be divided into two areas:  routine (preventive), and nonroutine.
Routine maintenance procedures are necessary to provide optimum
operational performance and minimum instrument downtime.  Nonroutine
maintenance is required as needed to rectify instrument failures.  A
constant failure rate will be established as a result of routine
maintenance.  Proper preventive maintenance will decrease this failure
rate to its minimal  level.
5.2   RoutineMaintenance of Automatic Monitors
      The magnitude  of specific Biaintenance requirements will be a
function of each individual monitor.  Factors affecting this demand
are engineering design and the reliability of components employed within
the system.  Initially, careful consideration of maintenance requirements
should be made from  the manufacturer's instrument manual.  These
requirements should  be incorporated into the operational log in the
form of periodic checks.  An example of these maintenance requirements
for a conductimetric SC^ monitor has been presented in section 4.0.
In addition to the periodic checks contained in the operational log,
detailed procedures  for use by the instrument technician should be
developed.  These procedures will insure continuity in the performance
of all levels of maintenance requirement.
      Several years  ago, maintenance procedures were developed by the
Air and Industrial Hygiene Laboratory of the California State Department
of Public Health.  California's Statewide Cooperative Air Monitoring
Network (SCAM) employs these procedures to assist its personnel in the
                                104

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operation, calibration, and maintenance of its automatic eculf-enz,
which is primarily photometric monitors.  These procedures provide i/.c
inexperienced as well as the more experienced personnel with an organized
approach to t .e identification and rectification of chemical, mechanical,
and electronic problems.  These published35 procedures can serve as an
example of the type of approach to employ while developing routine and
nonroutine maintenance procedures for use with other types of autonatic
monitors.
5.3   Nonroutine Maintenance of Automatic Monitors
      Equipment failures will require immediate remedial actions.  The
course of these actions will vary with the cause of the failure.  One
method of effective nonroutine maintenance is to first determine the
source of failure by means of diagnostic troubleshooting procedures.
In most instances the best available source of information pertaining
to corrective measures will be found in the manufacturer's instrument
manual.  The frequency, source, and corrective measures necessary for
rectifying the failure should be recorded in the operational log.
Periodically, a review of these failures will provide an insight into
new areas in which routine and preventive maintenance schedules should
be developed.  Thus, the frequency of nonroutine maintenance will be
reduced.
      5.3.1   Troubleshooting
      Failures requiring nonroutine maintenance often become obvious to
the instrument technician upon visual inspection of the malfunctioning
instrument.  In these cases the need for troubleshooting procedures
for the identification of problem areas is not necessary.  When visual
inspection does not lead to an obvious solution, a diagnostic

                               105

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 troubleshooting approach may be employed to locate the problem area.  In
 many cases detailed troubleshooting guides are provided by the
 manufacturer.  In other cases it will be difficult to develop detailed
 guides without a complete knowledge of the physical, chemical, and
 electronic parameters of the system.  For this reason, complex nonroutine
 maintenance requirements should be reserved for the manufacturer's staff
 of qualified service engineers.
      Often the failure, at first observation, appears to be complex or
 of unknown origin.  To avoid unnecessary service calls, a simple
 troubleshooting guide can be developed and employed by an instrument
 technician which will aid him in determining the extent of the instrument
malfunction.  The development of this troubleshooting guide can best
be accomplished if each component or subsystem of the monitor is
considered separately.  Several subsystems are common to most
monitors, e.g.:
      (a)  Electronic Subsystems—The electronic system can be
           subdivided into three areas:   the detection, amplification,
           and display of the electronic signal.  Electronic checks
           for each of these subsystems  are necessary to define the
           operational performance of the total electronic system.
           In this regard, it is essential  to maintain a reference
           record of prior electronic measurements, at several  vital
           points within the various subsystems, under normal
           operational conditions.   To insure that the values  are
           representative, they should be made after dynamic calibration
           of the monitor.  Thus the electronic system troubleshooting
           guide would consist of a table of reference points  relating
                                106

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     to the schematic diagram or  tne monitor,  and  corresponding
     to the electronic reference  values obtained.   Subsequent
     comparison of the "standard" data obtained as a result of
     these measurements and measurements made  during trouble-
     shooting efforts would enable rapid identification of
     faulty components and subsystems.
(b)  Mechanical Subsystems--Host  automatic monitoring equipment
     has a limited number of mechanical components.  Therefore,
     troubleshooting this subsystem is usually limited to such
     items as switches, valves, pumps, and the like.  One simple
     approach to troubleshooting  this system is to observe the
     mechanical functions of the  various suspect components for
     normal operation.  Also, substitution of  new components
     often leads to identification of problem  areas through the
     process of elimination.  Thus there are no real guidelines
     necessary in this particular area.  However,  tests such as
     pressure and flow measurements can be made to verify the
     normal operation of these components.
(c)  Chemical Subsystems—Automatic monitors employing reagents
     which include gases, liquids, and solids  have an Inherent
     source of malfunction.  Reagents are another variable within
     the system which are subject to deterioration, depletion,
     and contamination.  Two ways of troubleshooting this system
     are practical.  The reagents can be directly replaced or,
     in some cases, tested for proper composition or quality by
     measuring a property such as conductivity  or optical
     density.  A prior knowledge  of the reagents  physical and
                          107

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           chemical parameters is required.  This information, in sor.e
           cases, can be obtained from published literature on the
           specific method.  Often it is necessary to develop it
           in-house.  This can be accomplished by making the
           appropriate measurements, e.g., optical density, conductivity,
           purity tests, etc., on reagents from working systems.  This
           information should then be entered into the troubleshooting
           guide for future reference.
      (d)  Optical Subsystems—Troubleshooting of many automatic monitors
           employing optical  measurement principles can be accomplished
           by inserting apertures of various size into the light path to
           decrease the signal to the detector.  Caution should be
           exercised while employing this test to avoid misalignment of
           the optical system.
      As a result of the use of these subsystems troubleshooting guides,
the instrument technician will be in a better position to schedule the
proper amount of maintenance necessary, and provide in-house capabilities
in these areas.  If the malfunction is found to be beyond the in-house
maintenance capabilities, an expert service engineer should be called.
5.4  Maintenance of Station Facilities
      Maintenance requirements for the physical care of the remote
station should not be overlooked.  Schedules for general housekeeping
duties should be prepared.  This schedule should include, as a minimum,
the following items:
      0  Interior housekeeping—Cleaning of floor, walls, windows,
         benches, etc.
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0  Physical  maintenance of monitors--CleanIng of monitors,
   sample lines,  and  sample manifold.
0  Maintenance of heating and cooling systems—Change filters
   and oil motors as  prescribed by the manufacture.
0  Exterior maintenance—Lawn care and snow removal.
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6.0   CHARACTERISTICS OF AIR MONITORING EQUIPMENT
      To describe physical and performance characteristics of air
monitoring equipment, various special terms are used.  However, the
terms used are not always consistent.  Currently, many different
terms are used synonymously, whereas at other times, the same term
may have connoted different meanings.  Thus, the terms listed in the
orecedinn sections of this manual and other commonly used performance
terms require general definition to avoid confusion.
      In an attempt to generally define these terms, definitions from
technical publications and dictionaries were utilized.  Many terms
were redefined and new definitions were introduced.  In this effort,
there was considerable consultation  with members of APCO's Standardization
Advisory Committee and other colleagues.   Also, in addition to terms
directly related to these characteristics, other general descriptions
of air monitoring instrumentation are included in Section 6.4.
6.1   Physical  Characteristics
      Pollutant:   The specific  chemical substance or physical property
that the instrument is designed to detect.
      Manufacturer:  The name of the company or organization which
assembled,  fabricated, or otherwise produced the instrument.
      Model:   An identifying name or alphanumeric code other than the
tradename assigned by the manufacturer to identify the instrument.
      Tradename:   The name used by the manufacturer to identify a
particular instrument or series of instruments.
      Vendors:   The independent dealers or distributors of the
instrument, instrument supplies, parts, and service.
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       Size:   The overall  dimensions  of height, width,  and  depth of
 the instrument.   Basic instrument usually  includes  the sampling,
 analysis,  an   detection systems  and  may consist of  more than  one
 unit.   Components such as data display and/or  recording systems,
 pumps,  reagent containers, etc., are included  even  though  these
 may be  external  to the instrument cabinet.   It does not include items
 listed  by  the  manufacturer as auxiliary or accessory.
      Space Requirements:  The dimensions of height, width  and depth
 required for installation, operation and maintenance of an  instrument.
 It  includes space needed by all  auxiliary items and  equipment  and
 includes swinging space for cabinet access  doors  and panels.
      Auxiliary  Equipment:  The identification  and specifications of
 items designed for but not required for the analyzer to produce air
 quality data.
 6.2  Measurement Principles
      Sample Transfer  Devices:   Apparatus  that are  used to bring gases,
 vapors, fumes, and particulate matter into  intimate contact with a
 liquid  or  solid  reaction  medium,  or  to an enclosure where a physical
measurement is made.   These include  various  kinds of absorbing tubes,
 columns (wet or  dry),  and flasks,  and selectively permeable membranes
 (see glossary  for terms and definitions).
      How Measuring and  Metering  Devices:   Apparatus  used to measure
and meter  rate of fluid flow.  Two main classes are flowrate  meters
 antl quantity  (volume.)  meters.
      The  first  type is represented  by  area  or mass methods (rotameters);
differential pressure methods (impact  and pitot tubes,  orifices, nozzles
and venturi meters); caloric methods  (hot-wire catharometer); and impulse
methods (vane  and cup anemometers).
                                 Ill

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      The second type is represented by wet gas meters; dry gas meters;
bellows or diaphram meters; cycloidal, rotary disk and rotary pistons.
Wet and dry gas meters measure total volume only.  The average volume
rate may be calculated when the time interval is known (see glossary
for definition of specific flow measuring devices).
      Detection Methods:  Those techniques which quantitatively detect
the presence of a pollutant through direct physical measurement or
through indirect measurement of a reaction product, and include the
following:  colorimetry, conductimetry, amperometry, potentiometry,
and several physical methods such as:  absorption, emission, ultra-
violet, infrared, and correlation spectroscopies; mass spectrometry;
and nondispersive infrared absorption and flame photometry.  Inherent
in most detection devices is a reference system in which the instrument
output is compared to a known quantity such as background voltage or
current, or color intensity of a blank solution (see glossary for terms
and definitions).
      Signal  Presentation Devices:  Those components such as ammeters,
voltmeters, various types of recorders, digital readout units, computers,
and other data acquisition systems that are used to convert the analyzer
output (the signal  from the detection device) to a usable form.  The
analyzer output is usually in the form of a voltage, a current, or
power.  The output is related to the input by either a linear or non-
linear function.   The nonlinear function is usually an exponential one
but occasionally an undefined, nonlinear function is used (see glossary
for terms and definitions).
6.3   Performance Characteristics
      The emphasis of the following characteristics is on the performance
of the overall analyzer system and not on the performance of individual
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 components.
       6.3.1    Environmental  Requirements
       Temperature  Operating  Range:  The range of ambient temperature
 over which  the instrument will meet stated performance specifications.
       Humidity Operating Range:  The range of ambient relative numidity
 over which  the instrument will meet stated performance specifications.
       Vibration Operating Range:  The range, in type and intensity, of
 mechanical  vibration over which the instrument will meet stated perfor-
 mance  specifications.  The emphasis is on analyzers designed for
 portability in  field use in  motor vehicles and aircraft.
       6.3.2  Measurement Output
       Accuracy:  The difference between a measured value and the true
 value  which is  known or assumed usually expressed as +_ % of full scale.
       Full  Scale:  The maximum measuring limit for a given range.
       Interference:  An undesired positive or negative output caused
 by a substance  other than the one being measured.
       Interference Equivalent:  The portion of indicated concentration
 due to the  total interference, commonly found in ambient air.
       Linearity:   The maximum deviation between an actual instrument
 reading and the reading predicted by a straight line drawn between the
 upper  and lower calibration  points.
      Minimum Detectable  Change  CSensltiylty):  The smallest change in
inlet concentration which can be detected distinguishable from instrument
noise for outputs  at  mid-scale and 80 percent of full scale.  The magnitude
of change in inlet concentration required may differ with pollutant
concentration  and  may also be different for positive and negative dis-
placements.
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      Minimum Detectable Sensitivity (limitsof  Detection):  The smallest
amount of input concentration which  can  be  detected as the concentration
approaches zero.
      Noise:  Spontaneous deviations from a mean output not caused
by input concentration changes.
      Operational Period:  The period of time over which the instru-
ment can be expected to operate unattended within specifications.
      Precision:  The degree of agreement between repeated measure-
ments of the same concentration (which shall  be the midpoint of the
stated range) expressed as the average deviation of the single
results from the mean.
      Range:  The minimum and maximum measurement limits.
      6.3.3   Dynamic Response
      Zero Drift:  The change in instrument output over a stated
period of unadjusted continuous operation when the input concentration
is zero.
      Span Drift:  The change in instrument output over a stated
period of unadjusted continuous operation when the input concentration is
a stated upscale value.
      Lag Time:  (initial response time, t^):  The time interval from
a step change in the inlet concentration at the instrument inlet to the
first corresponding change in the instrument output distinguishable from
instrument noise.
      Rise Time 90 Percent:   The interval between the initial response
time and the time to 90 percent response after a step increase in
inlet concentration.
      Time to 90 Percent Response(tgQ):  The time interval from a step
change in the input concentration at the instrument inlet to a reading
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of 90 percent of the ultimate recorded concentration.
      Fall Time 90 Percent:  The interval between the initial  response
time and the time to 90 percent response (tgg) after a step decrease in
the inlet concentration.
      Response Time Constant (t ):  The time required for the  instrument
output to go from zero--to full scale--to zero in response to  a full-
scale square-wave chanqe in inlet concentration of the shortest duration
which will indicate full scale.  It is represented as tc = tr  + tf,
and is a measure of the instrument's ability to resolve pulsed inputs
of pollutants.
      Warmup Time:  The elapsed time necessary after startup for the
instrument to meet stated performance specifications when the  instru-
ment has been shut down for at least 24 hours.  A short wartnup period
is essential for instruments designed for portable field use.
6.4   GLOSSARY
      Absorber (contactor, contact column, scrubber):  A device for
bringing gases, vapors, fumes, and particulate matter into intimate
contact with an absorbing medium.  An absorber design with minimum
surface area and turbulence consistent with complete absorption of
interferents.  The following seven terms apply to the absorber:
            (a)  Bubble^:  An absorber in which the sample gas stream
      is broken up into many small bubbles by being forced through
      multiple openings or a fritted glass tip below the surface of
      the absorbing solution.  Bubblers may be tall or short depending
      on the efficiency of the absorption process.
            (b)  Helical Column;  A column made from glass tubing which
      has been coiled around a cylindrical form with one or more turns
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 and mounted with  its  axis vertical.  Gas-liquid flow is concurrent
 and may  be up or  down  the column.  High wetted-surface area is
 achieved by selecting  a tube diameter sufficiently small to insure
 that  the surface  tension of the solution will cause the entire
 inter-"or surface  to become wetted.
      (c)  Helix  Insert Column:  A high-surface-area type abrorber
 composed of a narrow tube with a glass or wire helix placed
 axially  and in contact with the interior column wall.  Liqu-id
 usually  passes down the column in a thin film over the helix.
 Gas flow may be concurrent or countercurrent.  The helix may
 also  be  wrapped around a center support with the gas-liqu-'d
 mixture  passing between the column wall and the center support-
      (d)  Impinger jet:  Sample air blown or aspirated onto o*-
 below the surface of the absorbing medium.  Absorption '.s
 increased by both high surface area and by turbulence.
      (e)  Mechanical  Scrubber:  A device designed to brig t'-^e
qas and  absorbing medium into intimate contact by mechcnica'1
agitation.   Absorption is increased by both high surface a^ea
a*d by turbulence.
      (f)  Packed Column:   A high-surface-area type absorbe>%
usually  a tubular column loosely filled with an  inert pedia
such as   Raschig rings, helices, crushed or sintered glass,  beads,
or other materials of various shapes.   Gas and liquid flow may
be concurrent or countercurrent with  absorption  taking  pi ae-
on wetted surfaces.  A single or a series of sintered glass
plates through which the gas-liquic! mixture is passed "nay be
used in  place of inert packing.

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             (<})  Spray jet:   Absorbing solution  forced through  an
       orifice at hiqh velocity and impacted on  the  interior surface of
       the absorbing chamber.   Gas is  absorbed through mixing ana
       turbulence created by  the impaction.   Kinetic energy is imparted
       to the liquid by hydraulic pressure,  sample air pressure, or by
       aspiration caused by the air flow into the chamber.
       Absorption:   A reaction in which gas  molecules are  transferred to
 a  liquid phase by  diffusion.   The driving force  is  a function of the
 concentration differential at the gas-liquid interface.   The process is
 favored  by hiqh interfacial areas, turbulence, and  high diffusion
 coefficients.  Absorbents  should have hiah  solubility and react
 irreversibly with  the absorbed gas.
       Absorption Spectroscopy (ultraviolet,  visible, infrared,  and
 microwave):   A physical  means of detecting  and measuring  the presence
 of compounds by the selective absorption  of electromagnetic radiation
 which  is  passed through  a  region containing  the  compounds.
      Amperometry (frequently erroneously called  coulometry; coulometry
 suggests an  instrument output the same as that which can  be predicted
 theoretically):  The reaction and measurement of a  pollutant with  a
 chemical solution which causes an electrical current proportional  to
 pollutant concentration.
       Analysis.  Automated;  A process  in  which samples are  collected and
 analyzed  automatically by  a device.
      Analysis. Semi-automated:  An automated process in which one  or
more steps in the same collection, and/or  analysis procedure
is  performed manually.
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      Anemometer:  An instrument for measuring and indicating the speed
of the wind.
      Calibrating Solution:  A solution, containing a known amount of a
substance having an effect equivalent to a pollutant concentration, that
is passed through the detection component during the static calibra-
tion of an analyzer.
      Calibration, Dynamic:  A calibration of the complete instrument
by means of sampling either a gas of known concentration or an artifi-
cial atmosphere containing a pollutant of known concentration.
      Calibration, Static:  A performance test of the detection and
signal presentation components accomplished by using an artificial
stimulus such as standard calibrating solutions, resistors, screens,
optical  filters, electrical signals, etc., which has an effect
equivalent to pollutant concentrations.
      Collection Efficiency;  The amount of substance absorbed or
detected divided by the total amount sampled expressed as percent.
      Col on'metry;  The measurement of a color change caused by the
reaction between a pollutant and a reagent solution whose color
intensity is proportional to pollutant concentration.
      Conduetimetry;  The measurement of a conductance change between
two inert electrodes placed in a reagent solution whose electrical
conductivity has been changed by the absorption of a pollutant.
      Corre1 ation Spectrometry:  A method of making qualitative and
quantitative measurements upon a gas, in which an absorption spectra
is cross-correlated in real time against the spectral replica of the
species  sought.
      Dead_Band_:  The range through which the Input to a system may be
varied without initiating an output response.  (Commonly applied to
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servo-systems such as recorders but is applicable to continuous  analyzers
as wel1.
      Detector (sensor, transducer):  A device which detects the
presence of an entity of interest and indicates its magnitude as the
deviation from a reference and converts these indications into a
signal (e.g., photometer, infrared bolometer, flame-ionization
detector, etc.).
      Dry-gas Meter  (bellows or diaphram meter):  A device which
measures total volume of a gas passed through it without the use of
volatile liquids.
      Emission Spectroscopy:  The detection and analysis of substances
by measuring characteristic spectra emitted by the substance when
excited by heat, radiation, electrical discharge, or other stimuli.
      Flame Photometry:  The detection and analysis of substances by
measuring the characteristic spectra emitted by excitation in a flame.
Narrow-band-pass optical filters may be used to isolate a characteristic
emission line when measuring a single substance.
      Fl uo rime try:  The detection and analysis of substances by measure-
ment of characteristic electromagnetic radiation (usually visible
liqht) emitted by the substance during exposure to radiation of higher
frequency (usually ultraviolet light).
      Impact and Pi tot Tubes:  Devices used to measure the velocity of
fluid flow by measuring the difference between perpendicular pressures
(on-axis  and off-axis) at various points in the flow stream.
      Instrument Inlet:  The opening at the instrument through which
the sample enters the analyzer, excluding all external sample lines,
probes, and manifolds.

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       lonization Detector (flame and radiogenic):  A very sensitive
 device capable of detecting the presence of pollutant ions produced
 by  passage through a flame or a region of radioactive emissions.  The
 flame  ionization detector is specific for combustible organic compounds;
 the radiogenic detector is relatively nonspecific.
       Luminescence;  An emission of light that occurs at low temperatures
 and that is not incandescence.  It is often produced by physiological
 processes, chemical action, friction, or by electrical action.
       Noise:   The spontaneous, short-term variations in response
 occurrinq periodically or randomly at any concentration but not
 caused by variations in pollutant concentration.
       Nozzle:  An orifice in the shape of a tube designed for measuring
 fluid  flow.  The tube is so shaped as to impart velocity to a fluid
 stream to produce pressure-flow characteristics which can be translated
 to flow rate.
      Orifice:  An opening through which a fluid can pass.   The orifice is
 so shaped as  to provide pressure-flow characteristics which can be
 translated to flow rate.  At fluid flow rates approaching sonic veloci-
 ties,  the orifice provides flow characteristics useful for controlling
 flow.
      Portability:   A qualitative term, used to describe the relative
ease with which an analyzer may .be moved about, which is divided
 roughly into two classifications—portable and stationary.   All
 analyzers can be used as stationary units but portable analyzers must
 be designed to withstand the rigors of vibration and acceleration
 found in transportation, must be lightweight, and must have short
wartnup times.
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       Potentlometry:   The measurement  of  the  reaction of a pollutant
 with a liquid reagent in  an electrochemical  (oxidation-reduction) cell
 using unpolarized electrodes.   The reaction  produces an electromotive
 force proportional to the pollutant concentration.
       Primary Standard:   A substance with a  known property which can be
 defined,  calculated,  or measured,  and  which  is readily reproducible.
 The  standard  may  be traceable  to  the National Bureau of Standards or
 other accepted standards  organization.
       Rotameter (variable area  flowmeter):  A flow-measuring device
 that operates at  constant pressure  and consists of a weight or float
 in a tapered  tube.  As the  flow rate increases, the float moves to a
 region  of larger  area and seeks a new  position of equilibrium in the
 tapered tube,  the position  being related to flowrate.
      Sample:   A  representative portion or specimen of an entity
 presented  for inspection.
      Sample,  Grab:   A single sample rapidly collected at any specific
 period  in  time.   Gaseous  samples are usually collected in a container,
 absorbed on a  solid or in a solution over a time period not less than
 one minute.
      Sample,  Integrated:  The sum of a series of small  samples or a
 continuous flow of sample collected over a finite time period (from
minutes to hours) so as to create a large average sample.   An inte-
grated  sample  is often stored for a period of time before analysis
although losses may occur.
      Sample. Automated:   A process in which  a sample is  collected
automatically by a programmed device.   The sample is  not  detected
or analyzed during collection.

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       Sampling,  Continuous:  A process in which samples are collected
 continuously  at  a  known  rate.
       Sampling,  Discontinuous:  A process in which a single integrated
 sample is  collected over a discontinuous, predetermined time interval
 or  until a  predetermined volume is collected.  The ratio of on-time
 versus  off-time  is stated.
      Sampling.  Random:  A process in which grab or integrated samples
 are collected at random  intervals.
      Sampling, Sequential:  A process in which a series of individual
 grab or integrated samples are collected one after the other at regular
 predetermined intervals.
      Sampling and Analysis,  Automated:   A process in which a sample
 is collected, detected, and analyzed automatically by a device.
      SecondaryStandard:  A substance having a property which is cali-
brated against a primary standard to a known accuracy.
      Selectively Permeable Membrane:  A device which allows  a pollutant
or class of pollutants to selectively diffuse through a gas barrier to
react with  a reagent.
      Signal-to-noise  Ratio:   The ratio of the magnitude of the signal
to that of the noise.   A ratio of two is  usually the smallest value
that can be used with  confidence.
      Standardization:  Adjustment of the instrument variables to make
the output conform to  predetermined or convenient values.
      Stock Solution:   A solution of known concentration from which
more dilute solutions  are prepared.
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      Venturi Tube:  A specially shupeJ tji-t: 1'or measuring the rate of
fluid flow.  The tube is so shaped as to impart velocity to a fluid
stream, but is followed by a gradually expanding cone which minimizes
frictional loss of kinetic energy, and which at the same time produces
pressure-flow characteristics which can be translated to flow rate.
      Wet-gas Meter:  A volumetric flow measuring device that measures
the total  gas volume by entrapping the gas in inverted cups or vanes  under
a liquid.  The buoyancy of the gas causes a rotation of the cups  or
vanes that is proportional to the volume which is indicated on a
precalibrated meter.
      Working Solution:  A solution prepared from a stock solution,
standardized against a primary or secondary standard, and used for
preparing  a range of calibrating solutions.
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 7.0  REFERENCES
 1.  "Guidelines:  Air Quality Surveillance Networks."  U.  S.
     Environmental Protection Agency.   Office of Air Programs
     Publication No. AP-98, May 1971.

 2.  Requirements for Preparation,  Adoption and  Submittal of Implementation
     Plans.  Federal Register, Volume  36,  No.  158,  August 14,  1971, p.  15492.


 3.  SAROAD Users Manual.   U. S.  Environmental Protection Agency,
     Office of Air Programs Publication No. APTD-0663.  July 1971.


 4.  Yamada, V. M.  "Current Practices in  Siting and Physical  Design
     of Continuous Air Monitoring Stations," J^  Air Pollution  Control
     Assoc.  Vol. 20 (April 1970),  pp. 209-213.


 5.  Yamada, V. M. and R.  J. Charlson.  "Proper  Sizing of  Sampling
     Inlet Line for a Continuous  Air Monitoring  Station,"  Environmental
     Science and Technology.  Vol.  3 (May  1969), pp. 483-484"^

 6.  Ace Glass Incorporated, Brochure  on Air Pollution Sampling Glassware,
     Vine!and, New Jersey  (1969).

 7.  Wohler, H. C., H. Newstine,  and D. Daunis.   "Caroon Monoxide and
     Sulfur Dioxide Adsorption on - and Desorption  from Glass, Plastic
     and Metal Tubings," J. Air Pollution  Control Assoc.   Vol. 17
     (November 1967), pp.  753-756.

 8.  Byers, R. L. and J. W. Davis.   "Sulfur Dioxide Adsorption and
     Desorption on Various Filter Media,"  J. Air Pollution  Control
     Assoc.  Vol. 20 (April 1970),  pp. 236-238.

 9.  Stevens, R. K.  Private Communications pertaining to  reactivity
     of tubing materials for sampling  low  levels of various air pollutants.
     Air Pollution Control Office,  Durham, North Carolina,  (March 1971).

10.  Mueller, P. K.  Private Communication, Progress Report,  Federal
     Contract CPA-70-24 (Performance Evaluation  Procedures  for
     Continuous Analyzers), October 1970.

11.  National Primary and  Secondary Ambient Air  Quality Standards
     (Appendix A-E).   Environmental  Protection Agency, FederalRegister.
     Vol.  36, No. 84 (April 30, 1971), pp. 8186-8201.
                                124

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 12.  Willard, H., L. Merritt, Jr., and J. Dean.  Instrumental Methods
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 13.  Crider, VI.  L.  Analytical Chemistry.  Vol. 37 (1965), p. 1770.

 14.  Brody, S. S. and J. E. Chaney.  J. Gas Chromatoqrapnv.  Vol. V
     (1966), p.  42.	'

 15.  Stevens, R. K., A. E. O'Keeffe, J. D. Mulik, and K. J. Krost.
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     Level," Presented at the 15/th Nat. ACS  Meeting, Minneapolis,
     Minnesota (1969).

 16.  Stevens, R. K., A. E. O'Keeffe, and G. C. Ortman.   "An Automated
     Gas Chromatographic Procedure to Measure Atmospheric Concentra-
     tions of Carbon Monoxide and Methane."  Presented  at the llth
     Conference  on Methodoian Air Pollution and Industrial Hygiene
     Studies, University of California, Berkeley, California (March 30
     to April 1, 1970).

 17.  Hemeon, W.  L. C., G. F. Haines, Jr., and H. M. Ide.  J. Air
     Pollution Control Assoc.  Vol. 3, No. 22 (1953).

 18.  Gruber, C.  W. and E. L. Apaugh.  J. Air Pollution  Control  Assoc.
     Vol. 4, No. 143 (1954).

 19.  Charlson, R. J., N. C. Ahlquist, H. Selvidge, and  P. B. MacCready,
     Jr.  "Monitoring of Atmospheric Aerosol Parameters with the
     Integrating Nephelometer," J. Air Pollution Control Assoc.
     Vol. 19, No. 12 (December 19691:

20.  Regener, V. H.  J. Geophysical Research.  Vol. 65  (1960),
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21.  Nederbragt, G. W., A. Van der Horst, and J. Von Duign.  Nature.
     Vol. 206, No. 87 (1965).

22.  Hodgeson, J. A., B. E. Martin, and R. E. Baungardner.  "Comparison
     of Chemiluminescent Methods for Measurement of Atmospheric Ozone,"
     Progress in Analytical Chemistry.  Vol. 5, New York:  Plenum
     Press, 1971,

23.  Elfers, L.  A.  Memorandum to K.  Foster, Air Pollution Control Office,
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     Instruments, April 8, 1969.
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24.  O'Keeffe, A. E. and G. C. Ortman.  "Primary Standards for Trace
     Gas Analysis," Anal. Chem.  Vol. 38, No. 760 (1966).

25.  Scaringelli, F. P., S.-A. Frey, and B. E. Saltzman.  "Evaluation
     of Teflon Permeation Tubes for Use with Sulfur Dioxide,"
     Amer. Ind. Hygiene Assoc.. J. Vol. 28, No. 260 (1967).

26   Scaringelli, F  P., A. E. O'Keeffe, E. Rosenberg, and J. P. Bell.
     "Preparation of Known Concentrations of Gases and Vapors with
     Permeation Devices Calibrated Gravimetrically," Anal. Chem.
     Vol. 42, No. 871 (1970).

27.  Rodes, C. E., J. A. Bowen, and F. J. Burmann.  "A Portable
     Calibration Apparatus for Continuous Sulfur Dioxide Analyzers,"
     Distritubed in a Refresher Course entitled:  "Selection and
     Calibration of Continuous Sulfur Dioxide Analyzers."  62nd
     Annual Meeting of the Annual  Meeting of the Air Pollution
     Control  Association, St. Louis, Missouri (June 1970).

28.  Chrisman, K. F, and K. E. Foster. . "Calibration of Automatic
     Analyzers in a Continuous Air Monitoring Program," Presented
     at the Annual Meeting of the Air Pollution Control Associa-
     tion, Detroit, Michigan (June 1963).

29.  Nishikawa, K-  "Portable Gas  Dilution Apparatus for the Dynamic
     Calibration of Atmospheric Analyzers," Presented at the Fifth
     Conference on Methods in Air Pollution Studies, Los Angeles
     (January 1963).

30.  Hodgeson, J. A. and B. E. Martin.  "Laboratory Evaluation of
     Alternate Chemiluminescent Approaches for the Detection of
     Atmospheric Ozone," Presented ACS Meeting, Chicago (Sept. 1970).

31.  "Tentative Method of Analysis for Sulfur Dioxide Content of the
     Atmosphere (Colorimetric)," Health Laboratory Science.  Vol. 7,
     No. 1 (1970), pp. 1-12.

32.  "Tentative Method of Analysis for Nitrogen Dioxide Content of
     the Atmosphere (Griess-Saltzman Reaction)," Health Laboratory
     Science. Vol. 6, No. 2 (1969), pp. 106-113.

33.  Altshuller, A. P., A. F. Wartburg, I. R. Cohen, and S. F. Sleva.
     "Storage of Vapors and Gases  in Plastic Bags," Intern. J. Air and
     Water Pollution.  Vol. 6, No. 75 (1962).

34.  Mueller, P. K.  "Guide to Operation of Atmospheric Analyzers,"
     Department of Public Health,  Air and Industrial  Hygiene
     Laboratory, State of California, Berkeley,  California.
                               126

-------
      Appendix A
Compilation of Monitors
         127

-------
                               APPENDIX A

                          COMPILATION OF MONITORS
Manufacturer
and address
Beckman Instrument Co.
2500 Harbor Blvd.
Fullerton, Calif. 92634
Bendix Corp.
Environmental Science Div.
1400 Taylor Ave.
Baltimore, Md. 21204
Pollutant
measured
Total
hydro-
carbon
do
Measure-
ment
principle
Flame
ioniza-
tion
do
Approx.
cost
$
2,000
1,200
to
7,800
Remarks
Without
recorder
do
Davis Instrument Co.           do
Route US 29 North
Box 751
Char!ottesvilie, Va. 22902

Mine Safety Appliances Co.     do
201 N. Braddock Ave.
Pittsburgh, Pa. 15208
do
do
 2,700
 2,000
do
do
Beckman Instrument Co.
2500 Harbor Blvd.
Fullerton, Calif. 92634



Total
hydro-
carbon ,
methane ,
4 carbon
monoxide
Gas
chroma to-
graphic



10,000 New
Instrument
with
recorder


Mine Safety Appliances Co.     do
201 N. Braddock Ave.
Pittsburgh, Pa. 15208

Tracer, Inc.                   do
6500 Tracer Lane
Austin, Texas 78721

Union Carbide Corp.            do
5 New Street
White Plains, N.Y. 10601
do
do
do
10,000
10,500
10,000
do
do
do
                                128

-------
                   Compilation of Monitors (continued)
Manufacturer Pollutant
and address measured
Beckman Instrument Co. Carbon
2500 Harbor Blvd. monoxide
Fullerton, Calif. 92634
Bendix Corp.
Environmental Science Div.
1400 Taylor Ave.
Baltimore, Md. 21204
Intertech Corp.
262 Alexander Street
Princeton, N.J. 08540
Mine Safety Appliances Co.
201 N. Braddock Ave.
Pittsburgh, Pa. 15208
Atlas Electric Devices Co.
4114 N. Ravenswood Ave.
Chicago, Illinois 60613
Barton Instrument Corp.
Div. of ITT
580 Monterey Pass Road
Monterey Park, Calif. 91754
Beckman Instrument Co.
2500 Harbor Blvd.
Fullerton, Calif. 92634
Beckman Instrument Co.
2500 Harbor Blvd.
Fullerton, Calif. 92634 &
Beckman Instrument Co.
2500 Harbor Blvd.
do
do
do
Sulfur
dioxide
do
do
Sulfur
dioxide
hydrogen
sulfide
Sul fur
dioxide
Measure- Approx.
ment cost
principle $
Infrared
do
do
do
Coulo-
metric
do
do
Flame
photo-
metric
gas C
Conduct i -
metric
3,500
2,600
to
3,200
3,300
1,700
to
2,700
4,400
5,000
2,600

3,560
Remarks
Without
recorder
do
do
do
Includes
recorder
with
automatic
zero or
span
Includes
recorder
Without
recorder
New instru-
ment with-
out recorder
Without
recorders
Fuller-ton, Calif. 92634
                                129

-------
                    Compilation  of  Monitors  (continued)
Manufacturer
and address

Bendix Corp.
Environmental Science Div.
1400 Taylor Ave.
Baltimore, Md. 21204
Pollutant
measured

Sulfur
dioxide


Measure-
ment
principle
Flame
photo-
metric

Approx .
cost
$
3,700
to
3,950


Remarks

With
recorder


Calibrated  Instruments
17 West 60th Street
New York, N.Y.  10023
Davis Instrument Co.
Division of Scott Aviation
Box 751, Route US 29 North
Charlottesville, Va  22902

Dynasciences
9601 Canoga Ave.
Chatsworth, Calif. 91311
do
do
do
Enviro Metrics, Inc.
13311 Beach Ave.
Marina Del Rey, Calif. 90291
do
  Conducti-   4,000
  metric
    do
  Coulo-
  metric
  Coulo-
  metric
(Fairstor)
2,300
2,300
1,900
Equipped
with
printout
device

Without
recorder
New
instrument
electro-
chemical
(dry)
without
recorder

   do
Intertech Corp.
262 Alexander Street
Princeton, N.O. 08540
do
           Coulo-
           metric
                                130
              3,300
        New
        instrument
        electro-
        chemical
        cell  (dry)
        without
        recorder

-------
                  Compilation of Monitors (continued)
Manufacturer
and address
Intertech Corp.
262 Alexander Street
Princeton, N.J. 08540
Kimoto Electric Corp. Ltd.
42 Funahashi-cho
Tennoji-Ku
Osaka, Japan
Leeds & Northrup
Sumneytown Pike
North Wales, Pa. 19454
Litton Systems, Inc.
3841 E. Santa Rosa Road
Camarillo, Calif. 93010
Meloy Laboratories
6631 Iron Place
Springfield, Va. 22151
Monitor Labs, Inc.
10451 Rosel! e
San Diego, Calif. 92121
Monitor Labs, Inc.
10451 Rose lie
San Diego, Calif. 92121
Philips, Inc.
Eindhoven, Netherlands
Pollution Monitors, Inc.
722 West Fullerton Ave.
Chicago, 111. 60614
Precision Scientific
3737 West Cortland Street
Chicago, 111. 60647
Process Analyzers, Inc.
fiann southwest Freeway
Pollutant
measured
Hydrogen
sulfide
Sulfur
dioxide
do
do
Total
sulfur
Sulfur
dioxide
do
do
do
do
do
Measure-
ment
principle
Col on" -
metric
Conduct 1 -
metric
Conductl -
metric
Colorl-
metric
Flame
photo-
metric
ColoM-
metrlc
Conductl -
metric
Coulo-
metric
Col or 1-
metric
Col or i-
metric
Coulo-
metrlc
Approx .
cost
$
3,300
2,900
4.9CO
5,000
3,300
1,500
1,500
5,000
2.000
2,000
4,000
Remarks
New
instrument
wi thout
recorder
With
recorder
(batch
system)
Without
recorder
do
do
do
do
do
New
instrument
without
recorder
do
Without
recorder
Houston, Texas 77036
                                131

-------
                   Compilation of Monitors (continued)
Manufacturer
and address

Scientific Industries
15 Park Street
Springfield, Mass. 01103
Technicon Controls, Inc.
Tarry town, N.Y. 10502
Tracor, Inc.
6500 Tracor Lane
Austin, Texas 78721 &







Milkens-Anderson Co.
4525 West Division Street
Chicago, 111. 60651
Atlas Electric Devices Co.
4114 N. Ravenswood Ave.
Chicago, 111. 60613
Pollutant
measured

Sulfur
dioxide

do

Sulfur
dioxide
hydrogen
sulfide






Sulfur
dioxide

Nitrogen
dioxide

Measure- Approx.
ment cost
principle $
Conducti- 2,000
metric

Col or i- 5,240
metric
Flame 5,700
photo-
metric
gas C






Colon'- 3,000
metric

Colon'- 2,830
metri c


Remarks

With
recorder

do

New
instrument
without
recorder
must
include
auto-
function;
price:
$3,200
With
recorder

With
recorder

Beckman Instrument Co.          do          do
2500 Harbor Blvd.
Fullerton, Calif.  92634

Beckman Instrument Co.          do        Coulo-
2500 Harbor Blvd.                         metric
Fullerton, Calif.  92634
Dynasciences                   do          do
9601 Canoga Ave.
Chatsworth, Calif.  91311
3,560   Without
        recorder
3,200   New
        instrument
        without
        recorder

2,300   New
        instrument
        electro-
        chemical
        transducer
        without
        recorder
                                132

-------
                   Compilation of Monitors (continued)
Manufacturer
and address
Enviro Metrics, Inc.
13311 Beach Ave.
Marina Del Rey, Calif.
90291



Intertech Corp.
262 Alexander Street
Princeton, N.J. 08540

Litton Systems, Inc.
3841 E. Santa Rosa Road
Camarillo, Calif. 93010
Pollution Monitors
722 West Fullerton Ave.
Chicago, 111. 60614

Pollutant
measured
Nitrogen
dioxide





do



do


do



Measure-
ment
principle
Coulo-
metrlc





Coulo-
metric


Colori-
metric

do



Approx.
cost Remarks
$
1 ,900 New
instrument
electro-
chemical
(dry)
without
recorder
3,300 New
instrument
without
recorder
5,000 Without
recorder

1 ,800 New
instrument
wi thout
recorder
Precision Scientific           do
3737 West Cortland Street
Chicago, 111. 60647

Scientific Industries          do
150 Herricks Road
Mineola, N.Y. 01103

Technicon Controls, Inc.       do
Tarrytown, N.Y. 10591

Milkens-Anderson Co.        Nitrogen
4525 West Division Street   dioxide
Chicago, 111. 60651
               do
               do
               do
            1,800   Without
                    recorder
            2,000   With
                    recorder
            5,240
do
             Colori-     2,800   Without
             metric              recorder
Atlas Electric Devices Co.
4114 N. Ravenswood Ave.
Chicago, 111. 60613

Beckman Instrument Co.
2500 Harbor Blvd.
Fullerton, Calif. 92634
Oxidant
(03)


   do
Coulo-      3,300   With
metric              recorder
Colori-     3,600   Without
metric              recorder
                                133

-------
                   Compilation of Monitors (continued)
Manufacturer
and address
Beckman Instrument Co.
2500 Harbor Blvd.
Fullerton, Calif. 92634
Bend ix Corp.
Environmental Science Div.
1400 Taylor Ave.
Baltimore, Md. 21204
Oasibi Corp.
3223 North Verdugo
Glendale, Calif. 91208
Intertech Corp.
262 Alexander Street
Princeton, N.J. 08540
Litton Systems, Inc.
3841 E. Santa Rosa Road
Camarillo, Calif. 93010
Mast Development Co.
2212 East 12th Street
Davenport, Iowa 52803
Rem, Inc.
3107 Pico Blvd.
Santa Monica, Calif. 90405
Technicon
Tarry town, N.Y. 10591
Gel man Instrument Co.
P. 0. Box 1448
Ann Arbor, Mich. 48106
Instrument Development Co.
1916 Newton Square So.
Pollutant
measured
Oxidant
(o3)
do
do
do
do
Oxidant
do
do
Soiling
do
Measure-
ment
principle
Cou To-
me trie
Gas phase
chenri lu-
minescent
UV
absorption
Coulo-
metric
Col or i-
metric
Coulo-
metric
Gas phase
chemilu-
mi nescent
Colori-
metric
Tape
Sampler
Tape
Sampler
Approx.
cost
$
3,000
4,700
to
4,950
4,000
3,300
5,000
1,100
3,500
5,240
1,000
400
Remarks
New
instrument
wi thout
recorder
Without
recorder
do
New
instrument
without
recorder
Without
recorder
Without
recorder
New
instrument
without
recorder
With
recorder
With reader
& recorder
Without
reader &
Reston, Va.  22070
recorder
                               134

-------
                   Compilation of Monitors (continued)
Manufacturer
and address
Pollutant   Measure-    Approx.
measured      ment       cost
            principle     $
                    Remarks
Research Appliance Co.
Route 8 & Craighead Road
Allison Park, Pa 15101
Soiling
Tape
Sampler
750
With reader
& recorder
Gelman Instrument Co.
P. 0. Box 1448
600 S. Wagner Street
Ann Arbor, Mich. 48106

General Metal Works
Air Sampling Equipment
Cleves, Ohio 45002

Meteorology Research, Inc.
P. 0. Box 637
Altadena, Calif. 91001
Research Appliance Co.
Route 8 & Craighead Road
Allison Park, Pa. 15101

The Staplex Co.
774 5th Ave.
Brooklyn, N.Y. 11232
Suspended    Filtration    500
partic-
ulates
   do
   do
   do
  do
             Integrat-
             ing
             nephel-
             ometer
350
            5,300
Filtration    350
  do
                           150
                    With flow
                    recorder
   do
      With
      recorder
      With flow
      recorder
      Without
      flow
      recorder
                                135

-------
         Appendix B
National Primary and Secondary
Ambient Air Quality Standards
             136

-------
                           Appendix ;j
                  National Primary and becondary
                  Ambient Air Quality Standards

      On April  30,  1971, Administrator William D. Ruckelshaus of the
Environmental Protection Agency established National Primary and
Secondary Ambient Air Quality Standards for six common classes of
air pollution:  sulfur dioxide, particulate matter, carbon monoxide,
photochemical oxidants, nitrogen dioxide, and hydrocarbons.  As
published in the  Federal Register,   these standards are designed to
protect public  health and welfare by setting limits on levels of
pollution in the  air.  They apply to all areas of the United States.
      The Environmental Protection Agency has authority, under
amendments to the Clean Air Act (1970), to set national primary and
secondary air quality standards for those air pollutants for which
air quality criteria are published.  Primary standards are designed
to protect human  health.  Secondary standards are designed to protect
against effects on  soil, water, vegetation, minerals, animals, weather,
visibility, personal comfort and well-being.  The criteria describe the
relationship between levels of pollution and the associated effects on
health and welfare.  Criteria for sulfur oxides, particulate matter,
carbon monoxide,  oxidants, hydrocarbons, and nitrogen oxides were
previously published by the Federal Government.
      With each set of criteria, the Federal Government has published
a control technology document.
      The primary and secondary standards for the six common classes
of pollution follow:
                                137

-------
Sulfur dioxide
      Primary standard^
      0   80 micrograms per cubic meter (0.03 ppm) annual arithmetic
             mean
      0   365 micrograms per cubic meter (0.14 ppm) maximum 24-hour
             concentration not to be exceeded more than once per year.
      Secondary standards
      0   60 micrograms per cubic meter (0.02 ppm) annual arithmetic
             mean
      0   260 micrograms per cubic meter (0.10 ppm) maximum 24-hour
             concentration not to be exceeded more than once per year.
      0   1,300 micrograms per cubic meter (0.5 ppm) maximum 3-hour
             concentration not to be exceeded more than once per year.
      Sulfur oxides in the air come primarily from the combustion of
      sulfur-containing fossil fuels.  Their presence has been associated
      with increased incidence of respiratory diseases, increased
      death rates, and property damage.
Particulate matter
      Primary standards
      0   75 micrograms per cubic meter, annual  geometric mean
      0   260 micrograms per cubic meter, maximum 24-hour concentration
             not to be exceeded more than once per year.
      Secondary standards
      0   60 micrograms per cubic meter, annual  geometric mean
      0   150 micrograms per cubic meter, maximum 24-hour concentration
             not to be exceeded more than once per year.
      Particulate matter, solid or liquid, may originate naturally or
      as  a result of industrial  processes and other human activities.
      By itself or in association with other pollutants,  it may injure
      the lungs or cause adverse effects elsewhere in the body.
                               138

-------
      Particulates also reduce visibility and contribute to property
      damage and soiling.
Carbon monoxide
      Primary and secondary standards
      0   10 milligrams per cubic meter (9 ppm).maximum 8-hour
             concentration not to be exceeded more than once per year.
      0   40 milligrams per cubic meter (35 ppm), maximum 1-hour
             concentration not to be exceeded more than once per
             year.
      Carbon monoxide is a product of incomplete burning of carbon-
      containing fuels, and of some industrial processes.  It decreases
      the oxygen-carrying ability of the blood and, at levels often
      found in city air, may impair mental processes.
Photochemical oxidants
      Primary and secondary standards
      0   160 micrograms per cubic meter (0.08 ppm), maximum 1-hour
             concentration not to be exceeded more than once per year.
             Measurement to be corrected for interferences due to
             nitrogen oxides and sulfur dioxide.
      Photochemical oxidants are produced in the atmosphere when
      reactive organic substances, chiefly hydrocarbons, and nitrogen
      oxides are exposed to sunlight.  They irritate mucous membranes,
      reduce resistance to respiratory infection, damage plants, and
      contribute to deterioration of materials.
Nitrogen oxides
      Primary and secondary standards
      0   100 micrograms per cubic meter (0.05 ppm), annual arithmetic
          mean
      Nitrogen oxides usually originate in high-temperature combustion
      processes.  The presence of nitrogen dioxide in ambient air has
                               139

-------
      been associated with a variety of respiratory diseases.
      Nitrogen dioxide Is essential to the production of photochemical
      smog.
Hydrocarbons
      Primary and secondary standards
      0   160 mlcrograms per cubic meter (0.24 ppm), maximum 3-hour
             concentration (6 to 9 a.m.) not to be exceeded more than
             once per year.  Measurement corrected for methane.
      Hydrocarbons come mainly from the processing, marketing, and use
      of petroleum products.  Some of the hydrocarbons combine with
      nitrogen oxides in the air to form photochemical oxidant.

      Under the 1970 amendments, the States were given nine months
from the date that the standards are promulgated (i.e. April 30, 1971)
to submit plans for controlling the sources of pollution to meet the
standards.  EPA may allow a State up to 27 months to submit plans
for achieving secondary standards.
                              140

-------
   Appendix C
Conversion Tables
    141

-------
            Table C-1.  CORRECTION OF OBSERVED PERMEATION RATE

                     TO STANDARD TEMPERATURE (25.0° C)

                        FOR S02 PERMEATION TUBES3
Temp
°C
10.0
10.1
10.2
10.3
10.4
10.5
10.6
10.7
10.8
10.9
11.0
11.1
11.2
11.3
11.4
11.5
11.5
11.6
11.7
11.8
11.9
12.0
12.1
12.2
12.3
Correct-
Ion
factor^
0.280
0.283
0.285
0.287
0.290
0.293
0.295
0.298
0.300
0.303
0.306
0.308
0.311
0.314
0.316
0.319
0.322
0.322
0.324
0.327
0.330
0.333
0.336
0.339
0.342
Temp
°C
12.4
12.5
12.6
12.7
12.8
12.9
13.0
13.1
13.2
13.3
13.4
13.5
13.6
13.7
13.8
13.9
14.0
14.1
14.2
14.2
14.3
14.4
14.5
14.6
14.7
Correct-
ion
factor
0.345
0.347
0.351
0.353
0.356
0.360
0.362
0.366
0.368
0.372
0.375
0.378
0.382
0.385
0.388
0.392
0.395
0.399
0.402
0.402
0.406
0.409
0.412
0.415
0.419
Temp
°C
14.8
14.9
15.0
15.1
15.2
15.3
15.4
15.5
15.6
15.7
15.8
15.9
16.0
16.1
16.2
16.3
16.4
16.5
16.6
16.7
16.8
16.8
16.9
17.0
17.1
Correct-
Ion
factor
0.423
0.426
0.430
0.434
0.437
0.442
0.445
0.449
0.453
0.456
0.461
0.465
0.468
0.473
0.476
0.481
0.485
0.490
0.493
0.497
0.501
0.501
0.506
0.510
0.515
Temp
°C
17.2
17.3
17.4
17.5
17.6
17.7
17.8
17.9
18.0
18.1
18.2
18.3
18.4
18.5
18.6
18.7
18.8
18.9
19.0
19.1
19.2
19.3
19.4
19.4
19.5
Correct-
ion
factor
0.519
0.523
0.528
0.532
0.535
0.542
0.547
0.550
0.556
0.560
0.563
0.568
0.573
0.578
0.582
0.588
0.592
0.599
0.602
0.609
0.613
0.619
0.622
0.622
0.629
*G. P. Scargingelli, s. A. Frey, and B. E. Saltzman.
 Teflon Permeation Tubes for Use with Sulfur Dioxide
 Assn. J.. Vol. 28 (May-June 1967).

bMultiply by this factor.
                                142
  "Evaluation of
," Am.  Ind.  Hygiene

-------
Table C-l   (continued).
Temp
°C
19.6
19.7
19.8
19.9
20.0
20.1
20.2
20.3
20.4
20.5
20.6
20.7
20.8
20.9
21.0
21.1
21.2
21.3
21.4
21.5
21.6
21.7
21.8
21.9
22.0
22.1
22.2
Correc
ion
factor
0.634
0.640
0.646
0.652
0.658
0.662
0.667
0.676
0.680
0.685
0.690
0.694
0.699
0.704
0.714
0.725
0.730
0.735
0.741
0.746
Temp
°C
22.3
22.4
22.5
22.6
22.7
22.8
22.9
23.0
23.1
23.2
23.3
23.4
23.5
23.6
23.7
23.8
23.9
24.0
24.1
24.2
0.752 24.3
1
0.758 24.4
0.763
0.769
0.781
0.787
0.794
24.5
24.6
24.7
24.8
24.9
Correct-
ion
factor
0.800
0.813
0.820
0.826
0.830
0.833
0.840
0.848
0.855
0.862
0.866
0.870
0.877
0.885
0.893
0.901
0.917
0.926
0.930
0.935
0.943
0.952
0.957
Temp
°C
25.0
25.1
25.2
25.3
25.4
25.5
25.6
25.7
25.8
25.9
26.0
26.1
26.2
26.3
26.4
26.5
26.6
26.7
26.8
26.9
27.0
27.1
27.2
0.962 27.3
0.971
27.4
0.976 ! 27.5
0.990 ! 27.6
Correct-
ion
factor
1.000
1.010
1.020
1.026
1.031
1.042
1.053
1.064
1.070
1.081
1.093
1.099
1.111
1.117
1.130
1.136
1.149
1.163
1.170
1.183
1.191
1.198
1.212
1.220
1.235
1.242
1.250
Temp
°C
27.7
27.8
27.9
28.0
28.1
28.2
28.3
28.4
28.5
28.6
28.7
28.8
28.9
29.0
29.1
29.2
29.3
29.4
29.5
29.6
29.7
29.8
29.9
30.0



Correct-
ion
factor
1.266
1.282
1.290
1.299
1.307
1.325
1.333
1.342
1.351
1.370
1.379
1.399
1.409
1.418
1.429
1.439
1.46C
1.471
1.481
1.493
1.504
1.527
1.539
1.550



      143

-------
                     Table C-2.
PERCENT TRANSMISSION (XT) AND OPTICAL DENSITY (O.D.)
                    EQUIVALENTS
%T
100
99
98
97
96
95
94
93
92
91
90
89
88
87
86
85
84
83
82
81
80
79
78
77
76
O.D.
0.000
0.004
0.009
0.013
0.018
0.022
0.027
0.032
0.036
0.041
0.046
0.051
0.056
0.061
0.066
0.071
0.076
0.081
0.086
0.092
0.097
0.102
0.108
0.114
0.119
XT
75
74
73
72
71
70
69
68
67
66
65
64
63
62
61
60
59
58
57
56
55
54
53
52
51
O.D.
0.125
0.131
0.137
0.143
0.149
0.155
0.161
0.168
0.174
0.181
0.187
0.194
0.201
0.208
0.215
0.222
0.229
0.237
0.244
0.252
0.260
0.268
0.276
0.284
0.292
XT
50
49
48
47
46
45
44
43
42
41
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
O.D.
0.301
0.310
0.319
0.328
0.337
0.347
0.357
0.367
0.377
0.387
0.398
0.409
0.420
0.432
0.444
0.456
0.469
0.482
0.495
0.509
0.523
0.538
0.552
0.569
0.585
XT
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
O.D.
0.602
0.620
0.638
0.658
0.678
0.699
0.721
0.745
0.770
0.796
0.824
0.850
0.886
0.921
0.959
1.000
1.046
1.097
1.155
1.222
1.301
1.398
1.523
1.699
2.000
                          144

-------
   CONVERSION  FACTORS  FOR GAS-VAPOR CONCENTRATIONS—

              FOR  CONVERTING  ppm TO
Gas
Nitric oxide
Nitrogen dioxide
Sulfur dioxide
Ozone5
Methane0
Carbon monoxide
Formaldehyde
Carbon dioxide
Sulfur trioxide
Ammonia
Chemical
symbol
NO
N02
so2
°3
CH4
CO
HCHO
co2
S03
NH4
Molecular
weight
30.01
46.01
64.06
48.00
16.04
28.01
30.03
44.00
80.06
17.03
Factor3
1226
1880
2618
1961
655
1144
1227
1798
3272
696
aEach factor represents the concentration in yg/m  equivalent
 to 1 ppm by volume.  The figures were generated for 25° C
 760 mm Hg.


DTotal oxidant is reported as ozone.


°Total hydrocarbon is reported according to calibration used,
 normally in methane equivalents.
                          145

-------
                                   Table C-4.  CONVERSION FACTORS-LENGTH
x. Desired
X Units
Given x.
Units N^^
Inch
Foot
Yard
Mile
(Statute)
Micro-
meter
(micron)
Millimeter
Centimeter
Meter
Kilometer
Inch
1
12
36
6.3360
x. 104
3.937
x 10"5
3.937
x 10"2
3.937
x 10"1
39.27
3.927
x 104
Foot
83.33
x 10"3
1
3
5280
32.808
x 10"7
32.808
x 10"4
32.808
x 10"3
32.808
X 10"1
32.808
x 102
Yard
27.778
x 10"3
.3333
1
1760
10. .94
X 10"7
10.94
x 10"4
10.94
x 10"3
10.94
x 10"1
10.94
x 102
Mile
(Statute)
1.578
x 10"5
1.894
x 10"4
5.682
x 10"4
1
62.137
x 10'11
62.137
x 10"8
62.137
x 10"7
62.137
x 10"5
62.137
x 10~2
Micro-
meter
(micron)
2.54
x 104
30.48
x 104
91.44
x 104
1.6094
x 109
1
1 x 103
1 x 104
1 x TO6
1 x 109
Milli- Centi-
meter meter
25.4 2.54
304.8 30.48
914.4 91.44
1.6094 1.6094
x 106 x 105
1 x 10"3 1 x 10"4
1 0.1
10 1
1 x 103 1 x 102
1 x 106 1 x 105
Meter
2.54
x 10"2
30.48
x 10"2
91.44
x 10"2
1.6094
x 103
1 x 10'6
1 x 10"3
1 x 10"2
1
1 x 103
Kilo-
meter
2.54
x 10"5
30.48
x 10"5
91.44
x 10"5
1.6094
1 x 10"9
1 x 10"6
1 x 10"5
1 x 10"3
1
To convert a value from a given unit
units and beneath the desired  unit.
to a desired unit, multiply the given value by the factor  opposite the given

-------
                                     Table C-5.   CONVERSION FACTORS-AREA
N^Deslred
NSjnits
Given \.
units N.
Square
inch
Square
foot
Square
yard
Square
mile
(Statute)
Acre
Square
centimeter
Square
decimeter
Square
meter
Square
Vilometer
Square
inch
1
144
1296
40.144
x 108
62.73
x 107
15.5
x 10"£
15.5
15.5
x 102
15.5
\ 10E
Square
foot
6.9444
x 10'3
1
9
2.788
x 107
4.3560
x 104
10.764
x 10"4
10.764
x 10"2
10.764
10.764
x 106
Square
yard
77.1605
x 10"5
0.1111
1
3.098
x 106
4840
1.1960
x 10"4
1.1960
x 10"2
1.1960
1.1960
x 106
Square
mile
(Statute)
2.49
x ID'10
3.587
x 10'8
3.228
X 10"7
1
15.625
x 10"4
3.8610
x 10-11
3.8610
x 10"9
3.8610
x 10"7
3.8610
x 10"1
Acre
15.94
x 10-6
2.296
x 10"5
2.066
x 10"4
640
1
2.4/1
x 10'8
2.471
x 10'6
2.471
x 10"4
2.471
x 102
Square
centimeter
6.452
929.0341
83.61
x 102
2.589998
xlO10
4046.873
x 104
1
1 x 102
1 x 104
1 x 1010
Square
decimeter
6.452
x 10"2
929.0341
x 10"2
83.61
2.589998
x 108
4046.873
x 102
1 x 10"2
1
1 x 102
1 x 108
Square
meter
6.452
x 10~4
929.0341
x 10"4
83.61
x 10"2
2.589998
x 106
4046.873
1 x 10"4
1 x 10"2
1
1 x 106
Square
kilometer
6.452
x ID'10
929.0341
x ID'10
83.61
x 10"3
2.589998
4046.873
x 10'6
1 x 10-10
1 x 10'8
1 x 10"6
1
To convert  a v
-------
                                           Table  C-6.   CONVERSION FACTORS-FLOW
§
N>Desired
\units
Given N.
units \
sec
min
hour
ft!
sec
min
n!
hour
L
sec
L
min
cm!
sec
cm!
min
sec
1
0.0167
2.778
x 10"5
28.317
x 10"3
4.7195
x 10"4
7.8658
x 10"6
1.000027
x 10"3
1.6667
x 10"5
1 x 10"6
1.6667
x 10"8
min
60
1
16.667
x 10"3
1.699
28.317
x 10"3
4.7195
x 10~4
6.00016
x 10"2
1.000027
x 10"3
6 x 10"5
1 x 10"6
M3
hour
3600
60
1
101.94
1.699
28.317
x 10"3
3.6
6.00016
x 10"2
3.6 x 10"3
6 x 10"5
ft!
sec
35.3144
0.5886
98.90
x 10'4
1
16.667
x 10"3
2.778
x 10"4
35.316
x 10"3
5.886
x 10'4
3.5314
x 10"5
5.886
x 10"7
ft3
min
21.1887
x 102
35.3144
0.5886
60
1
16.667
x 10"3
2.11896
35.316
x 10"3
2.1189
X 10"3
0.3531
x 10"4
ft3
hour
12.7132
x 104
21.189
x 102
35.3144
3600
60
1
127.138
2.11896
1.271
x 10"3
2.11887
x 10"3
I
sec
999.973
16.667
27. 777
x 10"2
28.316
47.193
x 10"2
7.866
x 10"3
1
1.6667
x 10"2
9.99973
x 10"4
5.9998
x 10"2
L
min
59.998
x 103
999.973
16.667
16.9896
X 102
28.316
0.4719
60
1
5.9998
x 10"2
9.99973
x 10"4
cm
sec
1 x 106
16.667
x 103
2.777
x 102
2.8317
x 104
4.7195
x 102
78.650
1000.027
16.667
1
60
on3
min
6 x 107
1 x 106
1.666
x 104
1.699
x 106
2.8317
4.7195
x 102
16.667
1000.027
16.667
x 10"3
1
     To convert  a value from a given  unit to a desired unit,  multiply the given value by the factor opposite the given units
     and beneath the desired unit.

-------
                                 Table  C-7.  CONVERSION FACTORS—WEIGHT
N. Desired
N. Units
Given \.
Units N.
Micro-
gram
Milli-
gram
Gram
Kilogram
Grain
Ounce
(avdp)
Pound
(avdp)
Ton
(U.S. short)
Tonne
(metric)
Micro-
gram
1
1 x 103
1 x ID6
1 x 109
64.799
x 103
28.349
x 106
453.59
x 106
985.185
x 109
1 x 1012
Milli-
gram
1 x 10" 3
1
1 x 103
1 x 106
64.799
28.349
x 103
453.59
x 103
987.185
x 106
1 x 109
Gram
1 x 10"6
1 x 10"3
1
1 x 103
64.799
x 10"3
28.349
453.59
987.185
x 103
1 x 106
Kilo-
gram
1 x 10"9
1 x 10'6
1 x 10~3
1
64.799
x 10"6
28.349
x 10"3
453.59
X 10"3
987.185
1 x 103
Grain
15.4324
x 10'6
15.4324
x 10"3
15.4324
15.4324
x 103
1
437.5
7000
14 x 106
1.543
x 107
Ounce
(avdp)
3.5274
x 10"8
3.5274
x 10"5
3.5274
x 10"2
35.274
22.857
x 10"4
1
16
3.2
x 104
3.5274
K 104
Pound
(avdp)
2.2046
x 10"9
2.2046
x 10"6
2.2046
x 10"3
2.2046
1 .4286
x 10"4
62.5
x 10~3
1
2000
2204.62
Ton
(U.S. Short)
1.1023
x ID'12
1.1023
x 10'9
1.1023
x 10'6
1.1023
x 10"3
7.143
x 10'8
3.125
x 10'5
5 x 10"4
1
1.10231
Tonne
(metric)
1 x 10-12
1 x 10"9
1 x 10'6
1 x 10"3
64.799
x 10'9
28.349
x 10'6
153.59
x 10"6
0.907185
1
To convert a value from a given unit to a desired unit, multiply the
units and  beneath the desired unit.
given value by the factor opposite the given

-------
                                         Table C-8.   CONVERSION  FACTORS—CONCENTRATION
in
O
NV Desired
N^units
Given \.
units Nv
?
?
ML
oz
ft.3
Ibs.
f7
grams
ft.3
Ibs. „
ToWft.3
grains
ft.3
?
1
1 x 10"3
.999973
1.00115
x 106
1.602
x 107
3.531
x 104
1.602
x 104
2.288
x 103
P|
NT
1000
1
9.99973
x 102
1.00115
x 109
1.602
xlO10
3.531
x 107
1.602
x 107
2.288
x 106
H2.
l
1.000027
1.000027
x 10"3
1
1.00118
x 106
1.602
x 107
3.531
x 104
1.602
x 104
2.288
x 103
oz_._
ft.3
9.989
x 10"7
9.989
x ID'10
9.988
x 10"7
1
16
3.5274
x 10"2
1.6
x 10~2
2.2857
x 10"3
Ibs.
ft.3
6.243
x 10"8
6.243
x lO"11
6.242
x 10'8
62.5
x 10"3
1
2.20462
x 10"3
1 x 10"3
1.4286
x 10"4
grams
ft.3
2.8317
x 10"5
2.8317
x 10"8
2.8316
x 10"5
28.349
453.59
1
453.59
x 10"3
6.4799
x 10"2
Ibs.
1000 ft.3
6.243
x 10"5
6.243
x 10"8
6.242
x 10"5
62.5
1 x 103
2.2046
1
14.286
grains
ft.3
4.37
x 10"4
4.37
x 10~7
4.37
x 10"4
4.375
x 102
7 x 103
15.43
7
1
           To convert a value from a  given unit to a desired
           the given units and beneath the desired unit.
unit, multiply  the given value by the  factor opposite

-------
                                 Table C-9.   CONVERSION FACTORS—VOLUME
\Desired
\units
Given N.
units N.
Cubic
yard
Cubic
foot
Cubic
inch
Cubic
meter
Cubic
decimeter
Cubic
centimeter
Liter
Cubic
yard
1
3.7037
x!0-2
2.143347
x 10~5
1.30794
1.3079
x TO"3
1.3079
x 10'6
1.3080
x TO"3
Cubic
foot
27
1
5.78704
x 10"4
35.314445
3.5314
X 10"2
3.5314
x 10~5
3.5316
x 10~2
Cubic
inch
4.6656
x 104
1728
1
6.1023
x 104
61.023
6.1023
x 10"2
61.025
Cubic
meter
0.764559
2.8317
x 10~2
1.63872
x 10"5
1
0.001
1 x 10"6
1.000027
x 10"3
Cubic
decimeter
764.559
28.317
1.63872
x 10~2
1000
1
1 x 10"3
1.000027
Cubic
centimeter
7.64559
x 105
2.8317
x 104
16.3872
1 x 106
1000
1
1000.027
Liter
764.54
28.316
1.63868
x 10~2
999.973
.99997
1.99973
x 10"4
1
To convert a value from a given unit  to a desired unit, multiply the given value by the  factor opposite the given
units and beneath the desired unit.

-------
                              Table C-10.  CONVERSION FACTORS-PRESSURE
NJ Desired
\units
Given N.
units N.
Atmos-
pheres
Bar
Millibar
In. Hg.
Cm. Hg.
Mm. Hg.
ID. H20
Lbs./sq. in.
Atmos-
pheres
1
9.8692
x 10"1
9.8692
x 10'4
33.421
x 10"3
1.3158
x 10"2
1.3158
x 10"3
2.4583
x 10"3
6.8046
x 10"2
Bar
1.0133
1
.001
33.864
x 10"3
1.3332
x 10"2
1.3332
x 10"3
2.49086
x 10"3
6.8947
x 10~2
Millibar In. Hg.
1013.3 29.921
1000 29.5296
] 29.5296
x 10"3
33.864 1
13.332 39-37°]
x 10"*
1.3332 39-37<"
x 10'J
2.49086 7<355f,
x 10"^
68.947 2.0360
Cm. Hg.
76
75.0059
75.0059
x 10"3
2.540005
1
0.1
0.186828
5.1715
Mm. Hg.
760
750.059
75.0059
x 10"2
25.40005
10
1
1 .86828
51.715
In. H20
406.788
401.467
40.1467
x 10"2
13.595
5.35251
0.535251
1
27.673
Lbs./sq. ir
14.696
14.504
14.504
x 10"3
4.9116
x 10"1
19.337
x 10"2
19.337
x 10"3
3.6136
x 10"2
1
To convert a value from a given  unit to a desired unit, multiply the given value by the factor opposite the given
units and beneath the desired unit.

-------
                                    Table C-ll.  CONVERSION FACTORS-TEMPERATURE
v Desired
\sUnits
Given \.
units ^v
Degrees
Fahrenheit
Degrees
Centigrade
Degrees
Rankine
Degrees
Kelvin
°F
1
1.8°C + 32
1.8°C + 32
°R - 460
1.8(°K-273) + 32
°C
.5555 x
(°F - 32)
1
.5555 x
(°R - 492)
°K - 273
°R
°F + 460
1.8°C + 492
1
1.8(°K-273) + 492
°K
.5555 x
(°F-32) + 273
°C + 273
.5555 x
(°R-492) + 273
1
                To convert a temperature from given units to desired units, use the formula  opposite  the given
                units and beneath the desired unit.

-------
Table C-12.   CONVERSION FACTORS-TIME (mean  solar)
N. Desired
\un1ts
Given N.
units N^^
Second
Minute
Hour
Day
Week
Month
Year
Second
1
60
3600
8.64
x 104
6.048
x 105
2.628
x 106
3.154
x 107
Minute
1.667
x 10"2
1
60
1440
1.008
x 104
4.380
x 104
5.256
x 106
Hour
2.778
x TO"4
1.667
x 10"2
1
24
1.680
x 102
730
8760
Day
1.157
x 10"5
6.944
x 10"4
4.166
X 10"2
1
7
30.42
365
Week
1.653
x 10"6
9.920
x 10"5
5.951
x 10"3
1.429
x 10"1
1
4.346
52.143
Month
3.805
x 10"7
2.283
x 10"5
1.370
x 10"3
3.287
x 10"2
8.333
x 10"2
1
12
Year
3.171
x 10"8
1.903
x 10~6
1.142
x 10"4
2.740
x 10"3
1.934
x 10"2
8.333
x 10"2
1

-------