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,
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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.
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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
-------
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
-------
Figure 2. Floor plan, remote air sampling station.
1
— *
o
1
0
=
— S.
1
o»
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
o>
cr
3
(D
r+
IN>
O
«•
1
o
A
O
3
(/»
= •=0
"«=0
o
(t>
VI
x-
-------
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
-------
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
-------
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
-------
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
-------
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
-------
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
-------
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
-------
Figure 13. Schematic diagram of a typical Integrating nephelometer.
en
oo
Air Sample
In
Flash Lamp
Reference
Phototube
Electrdm c
Control
Module
To Blower
-------
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
-------
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
-------
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
-------
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
-------
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
-------
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
-------
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.
-------
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
-------
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.
-------
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
-------
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
-------
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.
-------
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
-------
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
-------
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
-------
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
-------
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
-------
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
-------
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
-------
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
-------
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
-------
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
-------
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
SAROAD Hourly Data Form
Site Address
Parameter observed
Method
Stale Area Sue
I TT1
23* •> % " 6 9 ti>
Agency Project Time Year Month
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Parameter code Method Units OP
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OMB No. 158-R0012
Approval Expires 6/30/76
Figure 27. SAROAO hourly data form.
-------
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
Area Site
City Name
Site Address
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5
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7
8
9
0
1
St
21
Hr
22
Name
PARAMETER
Code
23 24 25 26 3
Method Units
28
29 30 31
33 34 35 3
1
7
DP
n
32
6
--
Name
PARAMETER
Code
37 38 39 40 a
Method . Units
42
1
43 44 45
47 48 49 50
DP
46
Name
PARAMETER
Code
51 52 S3 54 55
Method Units
47
56 58 S'J
61 6? 6} 6*
-
DP
60
Name
PARAMETER
Code
65 66 6' 68 69
Method Units
70
71 72 73
75/6 >i 78
1
(
DP
D
74
3210
43210
43210
Figure 28. SAROAD daily data form.
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
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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).
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to
10
SEC 468
(REV 10-61)
RECORD OF OPERATOR'S LOG
STATION
1 2 3 4 I
DATE:
OPERATOR.
GAS
t 7
MO.
8
:
9
.
h
DA.
10
11
-
YR.
12
13
a'
14
ITCM
15
!«
t—\
17
START
18
19
30
21
STOP
IM
23
24
25
PURGE
27
28 2fJ30
; T
1
COMMENTS
—
• Doy of W..k.
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.
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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.
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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
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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.
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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
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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
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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
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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
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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.
120
-------
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.
121
-------
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.
122
-------
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.
123
-------
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
-------
12. Willard, H., L. Merritt, Jr., and J. Dean. Instrumental Methods
of Analyses. New York: Van Nostrand Co., Inc. (May 1967),
pp. 76-78.
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.
"Gas Chromatography of Reactive Sulfur Compounds in Air at the ppb
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),
p. 3975. Vol. 69 (1964), p. 3795.
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,
Control of Fungus Growth in Reagent Systems of Automatic Air Monitoring
Instruments, April 8, 1969.
125
-------
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
------- |