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United States
Environmental Protection
Agency
Environmental Sciences Research
Laboratory
Research Triangle Park NC 27711
EPA-600/4-79-031
May 1979
Research and Development
Regional Air
Pollution Study
Quality Assurance
Audits
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U S Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are.
1. Environmental Health Effects Research
2 Environmental Protection Technology
3 Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6 Scientific and Technical Assessment Reports (STAR)
7 Interagency Energy-Environment Research and Development
8 "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the ENVIRONMENTAL MONITORING series.
This series describes research conducted to develop new or improved methods
and instrumentation for the identification and quantification of environmental
pollutants at the lowest conceivably significant concentrations. It also includes
studies to determine the ambient concentrations of pollutants in the environment
and/or the variance of pollutants as a function of time or meteorological factors.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
-------
EPA-600/4-79-031
May 1979
REGIONAL AIR POLLUTION STUDY
Quality Assurance Audits
by
0. Klein
F. Littman
Air Monitoring Center
Rockwell International
11640 Administration Drive
Creve Coeur, MO 63141
Contract No. 68-02-2093
Task Order 106
Project Officer
Stanley Kopczynski
Organic Pollutant Analysis Branch
Environmental Sciences Research Laboratory
Research Triangle Park, NC 27711
ENVIRONMENTAL SCIENCES RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
RESEARCH TRIANGLE PARK, NORTH CAROLINA 27711
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DISCLAIMER
This report has been reviewed by the Environmental Sciences Research
Laboratory, U.S. Environmental Protection Agency, and approved for publication.
Approval does not signify that the contents necessarily reflect the views and
policies of the U.S. Environmental Protection Agency, nor does mention of
trade names or commercial products constitute endorsement or recommendations
for use.
ii
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ABSTRACT
RAPS Quality Assurance audits were conducted under this Task Order
in continuation of the audit program previously conducted under Task
Order No. 58. Quantitative field audits were conducted of the Regional
Air Monitoring System (RAMS) Air Monitoring Stations, Local Air Monitoring
Stations (State of Illinois, St. Louis City, and St. Louis County), RAPS
helicopters and various measurement systems employed in the RAPS intensive
studies. Audit results are reported for systems measuring NO, NO , 03,
S02, total sulfur, total hydrocarbons, CH^ and CO. x
An investigation was conducted on the effect of Teflon particulate
filters on NO, NOp, Oo, and S02 concentrations in sampled air. Measured
sample losses are reported for synthetic pollutant -aair mixtures sampled
through new and used filters under both dry and humid conditions. The
investigation also revealed effects of humidity on the response of
analyzers to the various pollutants.
The accuracy of S02 calibration mixtures prepared with the commercial
dynamic calibration system employed in the audits was investigated. As
a result of this investigation and experence gained during the audits
the calibration system was modified to improve performance under field
conditions. The air scrubber and dilution air flow measurements and control
were modified to eliminate the undesirable effects of uncontrolled ambient
temperature and humidity. A new permeation tube holder was designed and
constructed to eliminate a recurrent air leakage problem.
m
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CONTENTS
Abstract 111
Figures vi
Tables vii
1.0 Introduction 1
2.0 Summary 2
3.0 Quality Assurance Audits 4
3.1 Instrumentation 4
3.2 Van Preparation 5
3.3 Van Operation 7
3.4 Bendix Portable Calibrator 7
3.5 Audit Standards 24
3.6 Results and Discussion 26
3.6.1 Data Analysis Methods 26
3.6.2 Audit Results 35
4.0 Filter Study 38
4.1 Experimental 38
4.2 Results and Discussion 40
5.0 Calibrator Operating Variables; an S02 Study 57
5.1 Equipment 57
5.2 Permeation Tube Variables 60
5.3 Temperature Excursions 62
5.4 Results and Discussion 62
Appendices
A. Audit Procedures for RAPS Instrument Systems 71
B. Modified Bendix Model 8861 Portable Calibration System 99
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FIGURES
Number Page
1 Winnebago Wiring 6
2 Installation of Instruments in Winnebago 8
3 Flow Calibration Equipment 10
4 Orifice No. 1 Calibration Curve 15
5 Orifices 1 and 2 Calibration Curve 16
6 Orifices 1 and 3 Calibration Curve 17
7 Orifices 1 and 4 Calibration Curve 18
8 Orifices 1 and 5 Calibration Curve 19
9 Orifices 1, 2 and 3 Calibration Curve 20
10 Orifices 1, 2, 3 and 4 Calibration Curve 21
11 Orifices 1, 2, 3, 4 and 5 Calibration Curve 22
12 NO Capillary Calibration Curve 23
13 Typical Audit Data Record 27
14 Schematic Layout for Filter Study 39
15 NO Pollutant 45
16 N02 + 03 Pollutant 47
17 Ozone Pollutant 49
18 S02 Pollutant (Tracer) 51
19 S02 + 03 Pollutant, S02 53
20 S02 + 03 Pollutant, 03 54
21 S02 Pollutant (Meloy) 56
22 Initial Equipment Configuration for S02 Study 53
23 Final Equipment Configuration for S02 Study 59
24 Meloy S02 Analyzer Calibration 61
25 Typical Strip Chart Trace, S02 Study 66
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TABLES
Number Page
1 Bendix 8861 Orifice Calibration Data 11
2 Data Summary - Rams Stations 29
3 RAPS Helicopters 31
4 St. Louis City and County Stations 32
5 Illinois Stations 33
6 Miscellaneous Audits 34
7 Summary of Results for Particulate Filter Study 41
8 Data Summary, NO Pollutant Monitor Labs Instrument 44
9 Data Summary NOp + Ozone Pollutant Monitor Labs
Instrument 46
10 Data Summary, Ozone Pollutant Monitor Labs Instrument 48
11 Data Summary, SO- Pollutant Tracer Instrument 50
12 Data Summary, Sulfur Dioxide Plus Ozone Pollutant
Tracor and Monitor Labs Instruments 52
13 Data Summary, S02 Pollutant Meloy Instrument 55
14 Effect of Permeation Chamber Flow Rate on Signal Response 63
15 Effect of S02 Permeation Tube Length 65
16 Effect of Cooling on Modified Bendix 8861P Calibrator 67
17 Effect of Heating on Modified Bendix 8861 Calibrator 68
v.n
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1.0 INTRODUCTION
The primary purpose of this task order was the support of the RAPS
quality assurance effort. This task order was a logical extension of Task
Order 58 under contract 68-02-1081. Under Task Order 58, quality assurance
audits were conducted in support of the 1975 Summer Intensive on the RAPS
helicopters, the MRI and Battelle airplanes, RTI and EMI vans, EPA aerosol
trailer, RAMS stations, portable 0, and CO monitors, and the gas chromatog-
raphy laboratory.
In the initial scope of work of this task order, emphasis was placed
on the preparation and deployment of various resources to perform calibra-
tions and audits of air monitoring systems employed in the RAPS 1976 winter
and summer field exercises. These resources consisted principally of a
Winnebago Mobile Laboratory Van equipped with a complete complement of
ambient air analyzers and a Bendix 8800 series portable calibrator. Sub<-
sequent modification to the task order included: an extension to provide
audit coverage to the 1976 Fall Intensive, selected audits of local agency
monitoring stations, a detailed study of the effect of the particulate
filters on the RAMS analyzers, and a detailed study and modification of the
Bendix portable calibrator.
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2.0 SUMMARY
The work performed under this task order was divided into four major
areas: first, preparation and calibration of the instrumentation and support
eouipment; second, audit of RAPS related instrumentation; third, modifica-
tions to the Bendix Model 8800 series calibrator; and fourth, special studies
concerning the particulate filters on the RAMS analyzers intake lines. Also
included as an appendix are the audit procedures developed for this task
order.
Preparation of the Winnebago Mobile Van consisted primarily of modifi-
cations to the electrical system and improved apparatus for securing the
instrumentation. Calibration curves were prepared for the Bendix 8861D
calibrator. The system was first leak-checked and then calibrated using
rising soap-film bubble meters. Data were converted to STP (0°C, 760 mm Hg,
dry). Standards for analyzer calibrations were obtained either directly
from the National Bureau of Standards (NBS) or traceable to NBS.
Field audits were performed in support of the RAPS 1976 Winter and
Summer Intensives and of selected RAMS stations. Audit results are given in
the text for RAMS stations, RAPS helicopters, Illinois agency sites,
St. Louis City and County sites and other miscellaneous audits. In general,
most instruments were good (errors within 15%); however, in selected cases
results were poor (errors > 20%).
An extensive study was also conducted on the effects of the Teflon
particulate filters placed in the inlet of the RAMS instruments measuring
atmospheric pollutants. Both new and aged filters were studied under con-
ditions of low and high relative humidity. Results indicate that: moist
air alters the instrument response for NO, 0.,, and S02; fresh filters tend
to attenuate the results, particularly for ozone; and humidity did not
affect instrument response to zero air.
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A thorough investigation of the Bendix 8861 calibrator's performance
in the delivery of SC^ was conducted. NBS permeation tubes were used in
studying flow rate over the tube, tube length, attitude of the permeation
tube chamber and ambient temperature. A Meloy SA185 analyzer was used to
monitor the results. As a result of this study, a new chamber was designed,
fabricated, and installed in the calibrator to minimize leakage and provide
adequate purge air temperature control.
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3.0 QUALITY ASSURANCE AUDITS
The St. Louis Regional Air Pollution Study was conducted to develop,
evaluate and validate air-quality simulation models on both regional and
local scales covering urban and rural areas, and stationary and mobile pollu-
tion sources. For this reason, a comprehensive, accurate and readily
retrievable data base of pollutants was developed for future model testing
and validation. To guarantee the quality of the data, it was necessary to
check the performance of the instruments used to make these pollution
measurements.
The quality assurance program provided an in-depth audit of the instru-
mentation by checking the instruments with gases of known composition. Any
discrepancy between the known gas composition and the concentration indicated
by the instrument was logged and reported within twenty-four hours.
Instruments which were checked included those at selected RAMS stations and
those of various RAPS Special Experiments, such as the RAPS helicopters.
3.1 INSTRUMENTATION
The following instruments were used in this study:
1) Bendix 8861P
2) Bendix 8861D
3) Monitor Labs Model 8440 Oxides of Nitrogen Analyzer
4) Tracor Model 270HA Atmospheric Sulfur Analyzer
5) Meloy Model SA 185-2 Total Sulfur Analyzer
6) Bendix Ozone Monitor
7) Monitor Labs Model 8410 Ozone Analyzer
8) MRI Integrating Nephelometer
9) Rikadenki five pen recorder
10) Beckman 6800 Gas Chromotograph
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Out of the above list, the following instruments were mounted in the
Winnebago Van:
1) Monitor Labs Model 8440 Oxides of Nitrogen Analyzer
2) Tracer Model 270HA Atmospheric Sulfur Analyzer
3) Monitor Labs Model 8410 Ozone Analyzer
4) MRI Integrating Nephelometer
5) Rikadenki five pen recorder
3.2 VAN PREPARATION
To prepare the Winnebago Laboratory Van for field use it was first nec-
essary to strip out all wiring and accessory internal batteries. It had been
demonstrated during the previous intensive effort period that the use of
batteries and an inverter to generate 115V power was unsatisfactory due to
excessive current drain. The exterior-mounted ONAN power generator had been
installed but power connections were incomplete.
All wiring was traced out and labelled and a color coded circuit diagram
was prepared (Figure 1) showing all of the breaker panels, generators and
switches necessary to the operation of the electrical system of the van.
The system was made operational using either the self-contained 115 volt
ONAN generator or 115 volts from an external source.
With this current configuration, a switch-over from generator to an ex-
ternal source (and vice versa) is awkward because of the power interruption.
The system could be improved by the incorporation of a shorting-type transfer
switch which would provide for an uninterrupted power transfer. This would
eliminate the necessity of relighting burners and awaiting restabilization
of the instruments which invariably drift when power is interrupted.
The Winnebago Laboratory Van was put in dependable running order. Both
gas tanks were removed and cleaned, all fuel lines were blown clean and
dried. The carburetor was rebuilt and readjusted. The carpet and draperies
were cleaned and a vinyl runner was installed to decrease carpet wear and
finally, the cabinets were covered with walnut grain contact paper to improve
the appearance of the interior. The continuous gas analyzers were installed
on a four inch thick styrofoam mattress pad and secured in place using a two
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inch square unistrut. A compression spring was incorporated in such a way
that the instruments were held in place by spring compression (Figure 2).
In addition to the continuous gas analyzers, the van was equipped with a wall
mounted integrating nephelometer on separate manifold. A Bendix 8861 cali-
brator, a Meloy S0? analyzer, and an alternate ozone analyzer were deployed
at various times during the course of audit activities on an as needed basis
and configured accordingly. The Bendix 8861 calibrator was completely
portable and was removed from the van and relocated on occasion as audit
requirements dictated.
3.3 VAN OPERATION
The EPA Winnebago Mobile Laboratory Van was deployed to various field
sites in the St. Louis area to perform audits of air monitoring systems
employed in the RAPS 1976 Winter and Summer field expeditions and of selected
RAMS stations. These audits were performed under the technical direction
and, in many cases, in the presence of the EPA Task Coordinator. Scheduling
of the audits was provided by the EPA Task Coordinator.
The audits were conducted using the Bendix 8861 portable calibration
systerr,. All spare equipment such as tubing, instrument parts, fittings,
test instruments (DVM, portable recorders) were conveniently carried in the
racks below the instrument shelf. The van was also used as a mobile labora-
tory when it became necessary to audit/calibrate instruments brought in for
a check. When fully operational, audit/calibrations were possible for NO,
N02, NOX, SOp, total sulfur, ozone, CH4> THC, CO and light scatter. Audits
of CH^, THC and CO analyzers were generally accomplished utilizing standard
gas cylinders and/or Teflon bags. When access to an (audit) analyzer was
required, a Beckman 6800 located in the RAPS laboratory was deployed. Instru-
ment output was observed using a Hewlett-Packard DVM and continuously moni-
tored by connecting the output of each instrument to the Rikadenki recorder.
3.4 BENDIX PORTABLE CALIBRATOR
The equipment used during calibration/audit work consisted of a Bendix
model 8861 portable calibration system capable of providing precise concen-
trations of 03, SO^, NO and N02- The 8861 system is composed of a model
8861P permeation tube assembly and a model 8861D dilution air/ozone generator
7
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assembly. The 8861 system is entirely self-contained within two aluminum
carrying cases.
The 8861P permeation tube assembly consists of a permeation tube
chamber, a pressure regulator/capillary flow system, temperature control
circuitry, and a battery pack. Chamber temperature was maintained at 30°C
+_ .01°C either by line power during calibration work or by battery pack
during transport. Chamber purge flow was provided by compressed air during
calibration work or by a small aquarium pump during transport.
The 8861D dilution air/ozone generator assembly consists of a pump, an
air drier, an air scrubber, pressure regulators, a series of temperature
controlled flow orifices, mixing chambers, and a temperature controlled,
constant current, ozone generator. Prior to use of the 8861D, it was neces-
sary to develop calibration curves for the flow controlling orifices.
Duplicate calibrations were performed at all available instrument pressures
from 30-100% of gauge on each of the five orifices. Several orifice combina-
tions were also calibrated yielding eight calibration curves in all.
All orifice calibrations were performed using the calibration train out-
lined in Figure 3. Initial leak checking of the 8861D was performed by
sealing the outlet line of the 8861D and pressurizing. Leaks were located
and eliminated with the aid of an in-line mass flow meter. Dry compressed
air was then allowed to flow through the 8861D orifice under calibration and
the exiting airflow rate was measured with a moving bubble flow meter.
Since the soap film would add an unknown amount of water vapor to an
otherwise dry air stream and introduce measurement error, the exiting air
stream was saturated with water vapor before measurement. Following the
determination of observed flow using the moving bubble flow meter, flow
rates were corrected to standard conditions of 0°C and 760 mm Hg, dry
basis. All calibration curves generated were maintained in the Bendix
8861D instruction manual.
Orifice calibrations were performed repeatedly during the course of
the audit program to insure the integrity of the orifice calibration data
in current usage. Typical calibration data is presented in Table 1.
Typical calibration curves are presented as Figures 4-12.
9
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25 PSIG
HUMIDIFIER
AP
MANOMETER
SOAP FILM
BUBBLE METER
FIGURE 3. FLOW CALIBRATION EQUIPMENT
10
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TABLE 1. BENDIX 8861 ORIFICE CALIBRATION DATA
% Of
Scale
30
40
50
60
70
80
90
100
*Correction
ORIFICE
Time For
1000 cc,
seconds
122.6
113.0
104.2
97.4
91.8
86.8
82.8
79.0
Factor = 0.88029
NUMBER 1
Observed
Flow
cc/minute
498.4
530.9
575.8
616.0
653.6
691.2
724.6
759.5
Flow at
Standard
Conditions
438.7
467.3
506.9
542.3
575.4
608.4
638.8
668.6
CF =
1°
T
P-Pw
where
To
T
P
Po
Pw
'K)
(continued)
Standard Temperature (273.2
Ambient Temperature; °K
Ambient Pressure, mm Hg
Standard Pressure (760 mm Hg)
Partial pressure of water at ambient temperature T, mm Hg
Flow at Standard Conditions = CF x Observed Flow
11
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TABLE 1 (continued)
I Of
Scale
30
40
50
60
70
80
90
100
30
40
50
60
70
80
90
100
30
40
50
60
70
80
90
100
ORIFICE NUMBER 1
Time For
1000 cc,
seconds
61.2
56.0
52.0
48.4
45.6
43.4
41.0
39.4
ORIFICE NUMBER 1
40.8
37.4
34.8
32.6
30.8
29.2
27.8
26.6
ORIFICE NUMBER 1
122.4
111.4
102.0
95.8
90.0
85.8
80.4
76.2
AND 2
Observed
Flow
cc/minute
980.4
1071.4
1153.8
1239.7
1315.8
1382.5
1463.4
1522.8
AND 3
1470.6
1604.3
1724.1
1840.5
1948.1
2054.8
2158.3
2255.6
AND 4
2451.0
2693.1
2941.2
3131.5
3333.3
3496.5
3731.3
3937.0
Flow at
Standard
Conditions
863.0
943.1
1015.7
1091.3
1158.3
1217.0
1288.2
1340.5
1294.5
1412.2
1517.7
1620.2
1714.9
1808.8
1900.0
1985.6
2157.6
2370.7
2589.1
2756.6
2934.3
3077.9
3284.6
3465.7
(continued)
12
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TABLE 1 (continued)
% Of
Scale
30
40
50
60
70
80
90
100
30
40
50
60
70
80
90
100
30
40
50
60
70
80
90
100
ORIFICE NUMBER
Time For
1000 cc,
seconds
120.6
110.4
102.0
96.0
91.0
86.2
82.0
78.6
ORIFICE 1, 2
152.8
140.0
129.4
121.6
114.2
109.0
103.4
99.2
ORIFICE 1, 2,
77.0
70.6
65.0
61.2
58.0
55.2
52.6
50.0
1 AND 5
Observed
Flow
cc/minute
2487.6
2717.4
2941.2
3125.0
3296.7
3480.3
3658.5
3816.8
AND 3
1963.3
2142.8
2318.4
2467.1
2627.0
2752.3
2901.4
3024.2
3 AND 4
3896.1
4249.3
4615.4
4902.0
5172.4
5434.8
5703.4
6000.0
Flow at
Standard
Conditions
2189.9
2392.1
2589.1
2750.9
2902.0
3063.7
3220.5
3359.9
1725.1
1882.8
2037.1
2167.8
2308.3
2418.4
2549.4
2657.2
3423.4
3733.8
4055.4
4307.3
4544.9
4775.5
5011.5
5272.1
(continued)
13
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TABLE 1 (continued)
ORIFICE 1, 2, 3, 4 AND 5
Time For Observed Flow at
x Of 1000 cc, Flow Standard
Scale seconds cc/minute Conditions
30 52.0 5769.2 5069.3
40 47.4 6329.1 5561.3
50 44.0 6818.2 5991.0
60 41.2 7281.6 6398.2
70 39.8 7537.7 6623.2
80 36.6 8196.7 7202.2
90 35.0 8571.4 7531.5
100 33.4 8982.0 7892.3
14
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80-
70-
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•z.
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=c
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10-
400 50 500 50 600 50 700
CC/MIN.
FIGURE 4. ORIFICE NO. 1 CALIBRATION CURVE
15
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100 -
90-
80 -
70 -
0 60 -
o
oo
CD
50 -
a 40 -j
LU
CD
Z3
SJ 30-
20-
10-
700 800 900 1000 1100 1200 1300 1400
CC/MIN.
FIGURE 5. ORIFICES 1 AND 2 CALIBRATION CURVE
16
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UJ
CD
Z
V—4
Q
ct
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o:
LU
CD
100
90 -
80 -
70-
60 -
50 -
40 -
30 -
20 -
10-
1200 1300 1400 1500 1600 1700 1800 1900
CC/MIN.
FIGURE 6. ORIFICES 1 AND 3 CALIBRATION CURVE
17
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100 -
90 -
80 -
^ 70 -
o
oo
fe 60 H
o 50 -
•z.
t—(
I 40 -
LU
CD
I 30 -
20 -
10 -
2000 2200 2400 2600 2800 3000 3200 3400
CC/MIN.
FIGURE 7. ORIFICES 1 AND 4 CALIBRATION CURVE
18
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100 -
90
80
uj 70
«=c
oo
u_ 60
50-
§ 40
o;
30
20
10
^i'i'i•r^i'|•|
2000 2200 2400 2600 2800 3000 3200 3400
CC/MIN.
FIGURE 8. ORIFICES 1 AND 5 CALIBRATION CURVE
19
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LU
O
oo
100 -
90 -
80 -
70 -
u. 60 -
o
1 50 H
CD
LU
CD
CD
40 -
30 -
20 -
10 -
T I I I | 1
1700 1900 2100 2300 2500 2700 2900
CC/MIN.
FIGURE 9. ORIFICES 1, 2 AND 3 CALIBRATION CURVE
20
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UJ
o
oo
O
<
UJ
CD
TOO
90
80
70
60
50
40
30
20
10
3400 3600 3800 4000 4200 4400 4600 4800 5000 5200
CC/MIN.
FIGURE 10. ORIFICES 1, 2, 3 AND 4 CALIBRATION CURVE
21
-------
LU
oo
LJ
CD
100 -
90 -
80 -
70 ~
60 -
50 -
40 -
30 -
20
10 -1
5000 5500 6000 6500 7000 7500 8000
CC/MIN.
FIGURE 11. ORIFICES 1, 2, 3, 4 AND 5 CALIBRATION CURVE
22
-------
TOO -
90 -
80 -
70 -
o
oo
u_ 60 ~
o
50 -
40 -
30 -
20 -
10 -
Q
<
a:
LU
CD
234
CC/MIN.
1 r
T
6
FIGURE 12. NO CAPILLARY CALIBRATION CURVE
23
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3.5 AUDIT STANDARDS
The calibration standards employed during the course of the audit pro-
gram were obtained either from the National Bureau of Standards (NBS) direct-
ly or from vendors supplying certification of analysis. In the latter case
the vender's analysis was certified by the Environmental Protection Agency
before the standard was submitted for use. The following specific gas
sources and/or techniques were used during the program to assure quality in
the audit standards.
Sulfur Dioxide (SQ?)
NBS Standard Reference Materials (SRM) 1625, 1626, and 1627, were used
exclusively throughout the project. The choise of a 10 cm, 5 cm, or 2 cm
permeation tube was governed by the operating range and sample flow rate of
the analyzer audited. The source gas permeation tube was maintained at con-
stant temperature (30.00°C +_ ,05°C) during use. Audit concentrations were
prepared by quantitative dilution of the source gas with ultrapure air.
Nitric Oxide (NO)
NBS SRM 1684, 100 ppm NO in nitrogen, was typically employed. This
cylinder was equipped with a low internal volume, stainless steel regulator
which was routinely evacuated and purged prior to withdrawal of cylinder con
tents for audit gas preparation. The cylinder was used either directly by
quantitative dilution and subsequent introduction of the audit gas to the
analyzer under test or it was used to certify a working standard. In the
latter case, the NBS cylinder was used to calibrate an oxides of nitrogen
analyzer and a vendor-supplied NO standard was then certified by analysis
under identical instrument operating conditions. The working standard, with
NBS traceability, was then used during field audits.
Nitrogen Dioxide
Nitrogen dioxide was generated by gas phase titration of nitric oxide.
A constant-current, constant temperature, ozone generator within the portable
calibrator served to provide the ozone for the titration. The procedure
employed to accomplish the gas phase titration is described in Appendix A.
24
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Ozone (03)
Ozone was generated within the portable calibrator as described above.
The concentration produced was a function of lamp current and was routinely
certified by gas phase titration of nitric oxide. The oxides of nitrogen
analyzer aboard the van served to monitor each titration performed for the
purpose of certifying the ozone concentration being delivered from the
portable calibrator during an audit. Frequent pre-audit and post-audit
certifications were performed to insure the integrity of the results
obtained in the field.
Total Hydrocarbons (THC). Methane (CH^). and Carbon Monoxide (CO)
THC, CH., and CO audit gas concentrations were derived from cylinders.
Generally, the cylinders were vendor supplied and EPA certified. The
standards were low level and prepared in air so that the cylinder contents
could be introduced to an analyzer without prior dilution. The cylinders
were either employed in the field with the contents introduced directly to
the analyzer being audited, or used to prepare an audit gas sample in a
Teflon bag. In the latter case, the bag was taken to analyzer to be audited
and the contents introduced to the analyzer.
NBS SRM 1681, 1000 ppm CO in nitrogen was used on occasion to certify
the contents of vendor supplied CO standards. NBS SRM 1658, 1659, and 1660,
CH. standards in air, were not available during the course of the study.
Zero Air
The source of zero air most commonly used during audits was vendor
supplied cylinder air certified by the vendor to meet the following specifi-
cations:
THC (as CH4) < 10 ppb
CO < 10 ppb
NOX < 10 ppb
S02 < 1 ppb
This zero air was also used routinely as diluent air during the prepara-
tion of audit gas concentrations where dilution of a source gas was required.
25
-------
On occasion, when an alternate source of dilution air was available, the
alternate source was substituted as diluent after quality was verified by
direct comparison to the cylinder gas. This practice was limited to audits
involving S02, NOX, and O.^. Audits involving THC, CH., and CO were performed
using zero air obtained only from the zero air cylinders.
3.6 RESULTS AND DISCUSSION
Various field sites in the St. Louis area were audited. Audits of air
monitoring systems employed in the RAPS 1976 winter and summer field
expeditions and of selected RAMS stations were also performed. RAMS stations
were audited in accordance with schedules provided by the EPA Task Coordi-
nator. A written report of each audit was prepared on the day following the
audit so that investigators could be advised of any errors discovered in
their instrument systems.
Audits were run by supplying a carefully calibrated source gas to the
instruments under test. Audits for ozone, NO-NO,, and sulfur dioxide were
performed using zero and four non-zero concentrations. Audits for CO, CH.
and total hydrocarbons were performed using gases of known concentration
supplied from a certified cylinder.
The results were recorded in tabular format. A typical data record is
shown in Figure 13. For each instrument, the concentration of the calibra-
tion gas was recorded in the "Auditor Value" column. The corresponding in-
strument reading (in volts) was recorded in the next column. This voltage was
translated into concentration using the applicable instrument transfer
equation, which is of the general form
ppm = MX + b
In the case of RAMS stations, the coefficients M and b were obtained
from the daily auto-calibration data reported in the station printouts.
For county and city stations, as well as helicopter instruments, the
corresponding conversion factors were obtained from the respective personnel.
3.6.1 Data Analysis Methods
The instrument values were then compared to the audit values by calcu-
26
-------
STATION 111
NO
NOv
6/25/76
03
. .350
.250
.150
j zero
3.2324
2.2680
1.4184
.0683
N0/N02 CONVERTER EFF
Instrument ppm = A+B
A = -0.005 B
.326
.226
.138
-.002
ICIEN'CY:
.350
.250
.150
zero
96%
3.3129
2.3364
1.4697
.0683
.334
.233
.144
-.011
(Auditor ppm)
0.951 A = -o.Oll 3 = 0.996
r2= 0.999 Sv v= 0.005
SO,
i Auditor
i Value
1 (PP'-O
j
Instrument
Reading
(volts)
Instr.
Reading
(ppm)
|
A = B
r2= S v=
CH4
Auaitor
Value
Instrument
Reading
Instr.
Reading
;
2
r = 0.999 Sv x= 0.006
TOTAL SULFUR
Auditor
Value
(ppm)
.700
.500
.300
.150
zero
Instrument
Reading
(volts)
3.3077
2.2680
1.4111
.6420
-.0048
Instr.
Reading
(pnm)
.614
.420
.261
.117
-.004
i = -0.009 B = 0.880
r2= 0.999 Sv. v= 0.009
TOTAL rfM'ROC -\R30NS
Auditor
Value
Instrument
Reading
Instr.
Reading
.142
zero
1.1938
.0708
.128 !
.000 '
j
A = .or," B = . 2?.c,
r2= .9998 Sy x= .002
CO
Auditor
Value
fppra)
40.60
20.15
3.43
5.29
zero
Instrument
Reading
(volts)
Instr.
Reading ;
(ppr )
3.8330 | 4C.9& ,
1.9213
1.6943
2.2705
.0463
20.50 :
3.54 ;
4.78 .
C. 018
1
A = -0.120 B =1.014
r2= 0.9997 Sy v= c.3195
XEPHEI/OMETER
Auditor
Value
Instrument
Reading
Instr. ;
Reading :
Auaitor
Value
(ppm)
2.20
zero
Instrument
Reading
(volts)
.9057
.0268
Instr.
Reading
(ppra)
1.89
-.062
Auditor
Value
(ppm)
2.20
zero
Instrument
Reading
(vclts)
.8276
.0170
Instr.
Reading
1.68
-.041
Auditor
Value
fnp-1
. .00-. 03
.00-. 03
1.00±. 03
4.00t.25
Instrument
Reading
fvolts)
.36
. C16
2.566
10.61
Instr. !
Reading :
;
*
i
i
t
j
j
i
t
A = -.062
r2=
Sy.x=
.887 A = -.041 3 .782
r2= 3>'.x=
A =
B
Sv.x=
FIGURE 13. TYPICAL AUDIT DATA RECORD
27
-------
lating the coefficient of a linear regression equation between the two sets
of values using a linear regression program of a Hewlett-Packard 65 cal-
culator. The equations used were
Zy. /EXA
A.-,,! .B(V-)
and
^y.; —J—L
B =
(Zx.)2
Zxi
where
A = intercept of regression line
B = slope of regression line
x. = audit gas concentration i
y. = instrument reading i
n = number of observations
As used here, the symbol Z means summation of values following the
symbol for index values, i, from 1 to n.
2
In addition, the square of the correlation coefficient, r , was deter
mined, which measures the degree of fit of the points to the least squares
2
straight line. When r =1, the correlation is said to be perfect, with
2
all points falling on the regression line. When r = 0, the relationship
between the two variables, x and y, is completely random.
2
The equation used by the program to determine r is
\ Exi^i
LEVi - -F—
r2-
The coefficient B, the slope of the regression curve, is an indication
of the accuracy of the instrument under test (assuming that the auditor
values are unbiased). A slope of 1.000 indicates complete correspondence, a
slope of 1.0500 or .9500 indicates a concentration or instrument dependent
error of +5% and -5% respectively in the instrument under test.
28
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3.6.2 AUDIT RESULTS
Tables 2-6 give the results for the audits of RAMS station instruments,
RAPS helicopter instruments, St. Louis City and County stations, Illinois EPA
stations, and miscellaneous audits.
Audits of the RAMS station instruments indicate that
1. The Monitor Lab NO NOX instruments show an average slope of .9944,
with a standard deviation of only .0532 for NO. For NO^ the slope
is 1.0247, the SD is somewhat larger at .0815. With one exception,
NOp converter efficiency was found to be 97% or better.
2. The Monitor Labs ozone instruments show a somewhat lower slope
with audit values .9287, with a SD of .0646.
3. The Tracer sulfur dioxide instrument gave an average slope of
.9815. However, this number is somewhat misleading since individ-
ual instruments were off by large amounts, as indicated by an SD
of .1623.
4. The total sulfur measurments from the Meloy and Tracer instruments
gave a rather low average slope of .8706 with a SD of .1263. The
Tracer S02 analyses were generally in closer agreement with the
audit test gas values.
5. The Beckman 6800 total hydrocarbon analyzers gave an average
slope of .9205 with a SD of .0933.
6. The Beckman 6800 methane analyzers gave an average slope of
.9251 with a SD of .0717.
7. The Beckman 6800 carbon monoxide analyzers gave an average slope
of .9795 with a SD of .0905.
Helicopter audits are summarized in Table 3. The results are similar
to those obtained at the RAMS stations.
1. The Monitor Labs recorders gave an average slope of .9760 for NO,
.9804 for NOX. The standard deviations were .0817 and .0712,
respectively. These results compare well with the RAMS stations.
35
-------
Inspection of the data indicates a negative calibration bias prior
to 1 November, which changed to a positive bias after that date.
2. The REM Scientific Company ozone analyzer showed an average slope
of 1.0153, with a SD of .1569. The average slope is somewhat
better than that of the RAMS sensors, however the SD is greater.
3. The Meloy Total Sulfur recorders gave an average slope of .9230
with a SD of .2168. This is comparable to the performance of the
RAMS Meloys.
4. The carbon monoxide analyzers gave an average slope of .9255,
with a SD of .0379.
Helicopter audits were conducted pre-flight and post-flight in an effort
to quantify the degree to which instrument drift may have occurred as a
result of the rigors of flight. The agreement between pre-flight and post-
flight audits was generally good with the exception of the ozone analyzers.
St. Louis City and County Stations use a wide variety of instruments,
as indicated on the summary tables. The data were, nevertheless, summarized
for each pollutant, since any future intercomparison of data will probably
not take instrument types into account.
A number of the City and County sites employ relatively old analyzers
of the wet chemical variety with such long response times that multipoint
audits could not be conducted within a reasonable period of time.
Data for NO indicate a large negative error (average slope of 0.4330),
with a large standard deviation (.3047). Data for NOp, taken only at 2
stations, appear to be unrelated to actual concentrations. Ozone data show
an average slope of 1.0867; however, the large standard deviation of .4099 is
an indication of the large spread of actual values. Values for total sulfur
indicate an average slope of .9294, but the standard deviation is again
large (.3586).
The carbon monoxide analyzers gave an average slope of 1.1288 with a
rather large SD of .1599.
The total hydrocarbon analyzers gave an average slope of .7904 with
a SD of .1993.
36
-------
Thus, the audit results indicate that data from these sources are
subject to large error and should be used with caution.
Two Illinois State EPA stations were audited. These stations have
Dasibi ozone analyzers, which gave a slope of .9902, with a standard devia-
tion of .0144. The SO^ values obtained by Technicon IV analyzers yielded
a correlation of .9556 with a standard deviation of .0649.
Miscellaneous audits included the audits of instruments used on the
DaVinci balloon, and various aircraft and vans used by expeditionary groups.
The results, shown in Table 6, indicate slopes ranging from .460 to 1.2650.
During the course of all audit work, a wide variety of analyzers,
support equipment, and monitoring configurations were encountered. Addi-
tionally, the analyzers used for aerial studies were not always audited
in place in the aircraft. In a number of instances, ambient temperatures
differed significantly from normal room temperature. In all cases the
responsible investigator was consulted prior to the audit in regard to
instrument specifications relevant to the audit and to insure that the
introduction of audit gas would simulate the introduction of the monitored
pollutant during normal operation. When the introduction of audit gas
through normal sampling lines was not possible, as in the case where high
by-pass flows existed in sample lines, audit gases were introduced through
auxiliary ports specifically designed for calibration.
37
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4.0 FILTER STUDY
The primary purpose of this part of the task was to conduct a study of
the effect of particulate filters on measurements by RAMS analyzers. The
pollutants of concern were sulfur dioxide (SCL), nitric oxide (NO) and ozone
(03).
4.1 EXPERIMENTAL
A study was made of the effects of new and used Teflon particulate
filters placed in the inlet of instruments measuring atmospheric pollutants.
The filters were 47 mm in diameter with an average pore size of 10 microns.
Both dry air and humidified air were used as diluent. Gases studied wereS02>
NO, Oo, N02 + Oo, SOp + DO- NO was obtained by diluting the contents of an
NO in nitrogen compressed gas cylinder. Ozone was obtained from a constant-
current ozone generator. N0~ was obtained by the gas phase titration of NO
with ozone. S02 was obtained from an NBS permeation tube. Equipment was set
up in such a fashion as to allow rapid change from one filter to another and
from dry air to wet air (Figure 14). The flow diagram shows airflow from the
cylinder to the Bendix calibrator, either directly or through a water bubbler.
Output from the calibrator entered a glass manifold for distribution.
Manifold air was sampled by an EG&G dew point hygrometer, the output of
which was monitored by a Leeds and Northrup recorder. The dew point hygrom-
eter was checked by deriving relative humidity from outdoor dew point and
temperature measurements and comparison to relative humidity measurements
taken with a sling psychrometer. Crosschecks were also made with relative
humidity measurements from the National Weather Service. In no case was a
difference greater than 5% noted.
The second line from the glass manifold led to a series of valves and
filters so that the gas stream could be shifted from one filter to another
(or none) without interruption or without opening the circuit. The filters
were replaced during the changeover from wet to dry diluent air and again
38
-------
LU C3
>- -z.
o
CM
o
C\J
CO
LU CO LU
—J I I—
h- O -Z.
O O
O LD CO Q.
o:
LU
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39
-------
during the changeover from pollutant to pollutant. The "used" filters were
taken from station 120. Filter 'age' varied from five to thirteen days.
All filters taken were obviously "used": particulate matter was visible on
all.
Before the work was started a decision was made by the EPA Task Coordi-
nator to randomize the order of tests so as to remove any systematic bias as
the tests proceeded. Furthermore, it was decided that two replicates were
required per test condition. Proceeding in accordance with the above
directive the first randomization was made in the sequence of testing the
pollutants. The order was as follows:
1. S02 (Tracor and Meloy)
2. N02 + 03
3. NO
4. 03
5. S02 + 03
The random sequence established for the individual filter tests is
obvious from the tables of results (Tables 8-13). Nearly every test in-
volving a different pollutant and/or humidity condition was preceeded by
a run using zero gas. When the test was completed, the zero gas run was
repeated. Concentrations of pollutants observed represent an average of
at least 12 readings made 4 minutes apart after the system was judged to
have reached equilibrium.
4.2 RESULTS AND DISCUSSION
Table 7 summarizes the results of the particulate filter study. In
comparing wet and dry air results, it should be noted that no correction for
the volume added by water vapor has been included. This amounts to 1-1.5%
at the relative humidities encountered. Reproducibility of duplicate runs
was generally good, with standard deviations within a range of .001 to .008
ppm. Thus, changes of the order of 5% are significant.
The following conclusions can be drawn from the results for the pol-
lutants tested:
40
-------
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41
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Nitric Oxide (NO)
An increase of relative humidity from 5 to 50% results in about 10% at-
tenuation of the response of the NO analyzer. The presence of a particulate
filter appears to have no effect.
Nitrogen Dioxide NOp)
Moist air appears to have no effect on the N02 reading obtained from
mixtures of N02 + 03< A new particulate filter caused a 4% drop in the N02
reading for moist air, but had no effect on the N02 reading for dry air.
Ozone (0,)
Moist air enhanced the response of the instrument to ozone by 10%. A
fresh particulate filter resulted in a 23% decrease in ozone level. A used
filter had a lesser effect (approximately 8%). Analyzer response time was
significant. As a result, some compromise in data quality occurred yielding
apparent inconsistencies such as two significantly different observations
taken on the same filter tested twice in succession.
Sulfur Dioxide (SOp) - Tracer Analyzer
Moist air resulted in a significant signal attenuation (16%). The in-
troduction of a particulate filter did not affect the S02 level significantly.
Sulfur Dioxide - Ozone Mixtures
This mixture contained a much higher S02 concentration than the one
discussed above (.252 ppm vs. .085 ppm). However, the attenuation in S0£
measurement due to the presence of moisture was about the same (0.01 ppm).
The particulate filter produced no significant change in the S02 measurement.
No change in ozone level resulted from the use of moist air. A new
particulate filter resulted in a 12% reduction of ozone level, which dropped
to 5% when a used filter was introduced.
Sulfur Dioxide (SOp) - Meloy Analyzer
This instrument showed an enhanced response to the introduction of moist
air (11%); as before, the introduction of a particulate filter did not result
42
-------
in significant changes.
The results indicate:
1. Moist air alters the instrument response to NO, 0, and S02- This
effect can be alleviated by calibrating the instruments with air
of about the same relative humidity as that which will be sampled,
2. Particulate filters, especially fresh ones, have a pronounced
attenuating effect on the ozone level. This effect decreases as
the filter becomes conditioned, but remains significant (5-10%).
3. None of the analyzers employed in this testing were sensitive to
zero air humidity, with or without a filter.
Data for individual tests are shown in Tables 8-13 and Figures 15-21.
43
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TABLE 8. DATA SUMMARY, NO POLLUTANT
MONITOR LABS INSTRUMENT
I. Wet
A.
B.
C.
D.
E.
F.
G.
H.
II. Dry
A.
B.
C.
D.
E,
F.
G.
H.
air, 51% R.H., R.T. 70°F, NO
Zero Gas
1. No filter
2. New filter
3. Used filter
Used filter, NO
New filter, NO
Used filter, NO
New filter, NO
No filter, NO
No filter, NO
Zero gas
1. No filter
2. New filter
3. Used filter
air, 5.5% R.H., R.T. 70°F, NO
Zero gas
1. No filter
2. New filter
3. Used filter
No filter, NO
New filter, NO
Used filter, NO
Used filter, NO
New filter, NO
No filter, NO
Zero gas
1. No filter
2. New filter
3. Used filter
Cone. PPM
.005
.005
.005
.135
.135
.135
.135
.138
.138
.003
.002
.002
Cone. PPM
.001
.001
.001
.152
.153
.155
.156
.156
.156
.002
.002
.003
44
-------
,16
* = DRY GAS
A = WET GAS
..._•:.*.
.15
Q.
Q-
.13
NONE
NEW
USED
FIGURE 15. NO POLLUTANT
45
-------
TABLE 9. DATA SUMMARY, N0? + OZONE POLLUTANT
MONITOR LABS^INSTRUMENT
Wet air, 40.5% R.H., R.T. 70°F, N02 +
A. Zero Gas
Cone. N00, PPM
1. No filter .005
2. New filter .004
3. Used filter .006
B. Used filter, N02 + 03 .161
C. New Filter, N02 + 03 .155
D. No filter, N02 + 03 .162
E. No filter, N02 + 03 .164
F. New filter, N02 + 03 .156
G. Used filter, N02 + 03 .165
H. Zero gas not repeated
II. Dry air, 5.5% R.H., R.T. 70°F, N02 + 03
A. Zero Gas Conc' N02' PPM
1. No filter .002
2. New filter .002
3. Used filter .003
B. Used filter, N02 + 03 .161
C. No filter, N02 + 03 .161
D. Used filter, N02 + 03 .162
E. No filter, N02 + 03 .163
F. New filter, N02 + 03 .160
G. New filter, N02 + 03 .162
H. Zero gas not repeated
46
-------
.17
<(> = DRY GAS
.16
*
*
*
OH
,14
NONE
NEW
USED
FIGURE 16. N02 + 03 POLLUTANT
47
-------
TABLE 10. DATA SUMMARY, OZONE POLLUTANT
MONITOR LABS INSTRUMENT*
I. Dry
A.
B.
C.
D.
E.
F.
G.
H.
II. Wet
A.
B.
C.
D.
E.
F.
G.
H.
air, 7.4% R.H., R.T. 70°F, 0,
o
Zero gas
1. No filter
2. New filter
3. Used filter
No filter, 03
New filter, 03
New filter, 03
Used filter, 03
Used filter, 03
No filter, 03
Zero gas
1. No filter
2. New filter
3. Used filter
air, 64% R.H., R.T. 70°F, 03
Zero gas
1. No filter
2. New filter
3. Used filter
New filter, 03
New filter, 03
No filter, 03
Used filter, 03
Used filter, 03
No filter, 03
Zero gas
1. No filter
2. New filter
3. Used filter
Cone. PPM
.005
.005
.005
.157
.120
.128
.144
.151
.163
.005
.006
.006
Cone. PPM
.005
.005
.005
.133
.137
.170
.157
.161
.180
.004
.005
.004
* Bendix ozone monitor in Winnebago exchanged for M.L. Extreme instrument
drift on Bendix.
48
-------
.17
.16
,15
4 = DRY BAS
A = WET GAS
D-
Q_
oo
O
.13
.12
NONE
NEW -
USED
FIGURE 17. OZONE POLLUTANT
49
-------
TABLE 11. DATA SUMMARY, SO- POLLUTANT
TRACOR INSTRUMENT
I. Dry
A.
B.
C.
D.
E.
F.
G.
H.
II. Wet
A.
B.
C.
D.
E.
F.
G.
H.
air, 8.1% R.H., R.T 70°F, SO.
L.
Zero Gas
1. No filter
2. New filter
3. Used filter
Used filter, S02
No filter, S02
New filter, S02
No filter, S02
New filter, S02
Used filter, S02
Zero gas
1. No filter
2. New filter
3. Used filter
air, 71% R.H., R.T. 63°F, S09
C.
Zero Gas
1. No filter
2. New filter
3. Used filter
New filter, S02
New filter, S02
No filter, S02
No filter, S02
Used filter, S02
Used filter, S02
Zero gas
1. No filter
2. New filter
3. Used filter
Cone. PPM
.000
.000
.000
.087
.087
.081
.084
.081
.082
.000
.000
.000
Cone. PPM
.000
.000
.000
.070
.070
.072
.072
.071
.071
.000
.000
.000
50
-------
.08
Q-
Q.
O
o
OL
.0?
4> = DRY GAS
A = WET GAS
-------
TABLE 12. DATA SUMMARY, SULFUR DIOXIDE PLUS OZONE POLLUTANT
TRACOR AND MONITOR LABS INSTRUMENTS
I. Dry
A.
B.
C.
D.
E.
F.
G.
H.
II. Wet
A.
B.
C.
D.
E.
F.
G.
H.
air, 7.6% R.H., R.T. 70°F, S0« + 0
2 3
Zero gas
1. No filter
2. New filter
3. Used filter
Used filter
Used filter
New filter
New filter
No filter
No filter
Zero gas
1. No filter
2. New filter
3. Used filter
air, 64% R.H., R.T. 70°F > SO, + 0,
c. O
Zero gas
1. No filter
2. New filter
3. Used filter
No filter
New filter
No filter
New filter
Used filter
Used filter
Zero gas
1. No filter
2. New filter
3. Used filter
Cone.
sp_2
.002
.002
.002
.251
.251
.242
.242
.251
.251
.002
.002
.002
Cone.
SO
*J\J r\
.002
.002
.002
.241
.231
.241
.231
.241
.241
.002
.002
.002
PPM
P_3
.004
.004
.004
.168
.176
.159
.161
.180
.182
.006
.006
.006
PPM
n
-3
.005
.005
.005
.178
.156
.178
.157
.171
.172
.004
.003
.004
52
-------
.26
O
w
S5 fe
M O
.25
O K
.23
NONE
* = DRY GAS
A a WET GAS
NEW
USED
FIGURE 19. S02 + 03 POLLUTANT, S02
53
-------
-------
TABLE 13. DATA SUMMARY, SCL POLLUTANT
MELOY* INSTRUMENT^
I. Dry
A.
B.
C.
D.
E.
F.
G.
H.
II. Wet
A.
B.
C.
D.
E.
F.
G.
H.
air, 7.3% R.H., R.T. 67°F, S00
C.
Zero Gas
1. No filter
2. New filter
3. Used filter
Used filter, S02
No filter, S02
New filter, S02
No filter, S02
New filter, S02
Used filter, S02
Zero gas
1. No filter
2. New filter
3. Used filter
air, 61% R.H., R.T. 67°F, SO,
L.
Zero Gas
1. No filter
2. New filter
3. Used filter
Used filter, S02
No filter, S02
New filter, S02
Ho filter, S02
New filter, S02
Used filter, S02
Zero gas
1. No filter
2. New filter
3. Used filter
Cone. PPM
-.008
-.008
-.008
.154
.151
.155
.160
.160
.163
-.009
-.018
-.016
Cone. PPM
-.004
-.007
-.006
.167
.169
.173
.173
.172
.173
-.008
-.018
-.018
*Meloy analyzer at RAMS station 102 was used to collect S09 data.
This test was not run until all of the other tests were completed.
55
-------
.18
.17
O-
D_
5-
o
.16
0 = DRT GAS
A = WET GAS
CM
O
oo
.15
NONE
NEW
FIGURE 21. S02 POLLUTANT (MELOY)
-------
5.0 CALIBRATOR OPERATING VARIABLES; AN S02 STUDY
This work is an extension of Task Order 106 using the modified Bendix
8861 portable calibration system and National Bureau of Standards S02 permea-
tion tubes in a study of the effect of several variables on the accuracy of
prepared S02 calibration gas mixtures. Variables investigated include flow
rate over the permeation tube, tube length, attitude of the permeation tube
chamber, and ambient temperature during the use of the 8861 calibration
system.
5.1 EQUIPMENT
The following equipment was used during this phase of the Task Order:
1. A Bendix portable calibrator (described in Section 3.4)
2. A Meloy S02 analyzer
3. An environmental chamber
The equipment employed during the first phase of testing was configured
as outlined in Figure 22. Scrubbed ambient air was used during all tests.
Scrubbing consisted of passage through Drierite, activated charcoal, and
Ascarite. Ascarite scrubbing of carbon dioxide proved necessary in order to
eliminate the variable suppression of S02 analyzer response due to changing
COp levels in the diluent air. Tests were performed to verify that C02
removal was complete by comparing the span response of the Meloy S02
analyzer with bottled zero air as diluent to the span response with ascarite
scrubbed air as diluent.
The equipment configuration during the second phase of testing is
displayed in Figure 23. An environmental chamber was constructed using a
wooden framework and cardboard sheeting to enclose the Bendix portable
calibration system. Components contained within the environmental chamber
are shown as being within a dotted line in Figure 23.
The Meloy S02 analyzer was calibrated prior to testing following
57
-------
BENDIX 88fclP
SO2 TO DILUTHR
_V '
OUTPUT-^
V
I
MELOY
INLET
EXHAUST
TO
ATMOSPHERE
BENDIX 8K,ID
-1 ~
-AMBIENT AIR IN
nun
/
DRIERVTE
ACTfVATED
CHARCOAL.
ASCARITE.
J
H-P RECORDER
O-5 V INPOT SIGNNL
H-P DIGITAL VOLT
METELR
FIGURE 22. INITIAL EQUIPMENT CONFIGURATION FOR S02 STUDY
58
-------
BENDIX8861D
AIR SUPPLY
BENDIX
TEMPERATURE
SENSOR IN
BLOCK
THERMISTOR
QVEN TEMp
UVLII i ti ir .
MONITOR
liumi IUt^
VARIABLE
.FLOW RATE
0-100 cc/MIN
c
PERM.
y
MOLECULAR
SIEVE
DRIERS
•Q TOGGLE
L_
EXHAUST TO
ATMOSPHERE
Equipment inside dotted line enclosed in chamber
for control tests at three different temperatures
*Provides air flow to purge permeation device
during transit
H.P.
RECORDER
FIGURE 23. FINAL EQUIPMENT CONFIGURATION FOR S02 STUDY
59
-------
standard procedures yielding the calibration data presented in Figure 24.
5.2 PERMEATION TUBE VARIABLES
An SO^ concentration of approximately 0.3 ppm was selected for testing.
At this concentration a 2 cm, a 5 cm, and a 10 cm S02 permeation tube could
be exchanged in turn within the permeation tube chamber without exceeding the
range of dilution airflow measurement within the Bendix 8861. The appropri-
ate dilution airflow rates were selected for the particular tube in use so
that the S02 concentration prepared should remain constant. Airflow over the
tube in use was varied using a mass flow controller with a range of 0-100
cc/minute. The effect of permeation tube chamber position was determined by
physically rotating the chamber through 90° between experiments. Chamber
temperature was monitored during the course of the study in two ways. The
Bendix platinum resistance thermometer embedded in the aluminum block sur-
rounding the Teflon permeation tube cylinder was monitored. In addition, a
small glass thermistor was placed within the tube cylinder and the actual
air temperature over the permeation tube was monitored by placing the therm-
istor in a voltage divider circuit and recording a voltage inversely pro-
portional to temperature. Thus, a change in air temperature could be
measured directly and without the time lag associated with the Bendix
temperature sensor.
The Meloy analyzer output voltage was monitored using a Hewlett-
Packard DVM and a Hewlett-Packard strip chart recorder. Once a stable trace
was obtained, readings were taken at 15 minute intervals and voltages were
converted to concentrations using the slope and intercept developed during
calibration of the Meloy analyzer.
Throughout this phase of testing, the sequence of operations was as
follows:
1. Permeation tube chamber placed in a horizontal position, purge
flow rate stabilized (5 cc/min., 10 cc/min., etc.), chamber
temperature at 30.0°C.
2. Recorder trace stable, analyzer signal level and chamber temper-
ature recorded.
60
-------
.3 -
.2 -
Q.
O-
.1 -
1 2
VOLTS
Cone. SOpj, ppm
0.00
0.10
0.20
0.30
Meloy Output, Volts
0.064
0.664
1.280
1.905
FIGURE 24. MELOY S02 ANALYZER CALIBRATION
61
-------
3. Chamber placed in a vertical position. Step 2 repeated.
4. Chamber returned to a horizontal position.
The results obtained are presented in Tables 14 and 15. A cypical strip
chart record is included as Figure 25.
5.3 TEMPERATURE EXCURSIONS
The second phase of testing involved the placement of the Bendix 8861
portable calibrator in an environmental chamber. Cooling of the system com-
ponents was achieved by exposing the chamber to a stream of outside air at
10°C. Heating was achieved by use of a strip heater. A blower and a damper
were employed for regulation of chamber temperature. This test was performed
with a 2 cm SO- permeation tube and at a purge flow rate over the tube of
5 cc/min. The results obtained are presented in Tables 16 and 17.
5.4 RESULTS AND DISCUSSION
A small effect was observed as the purge flow rate was varied over the
2 cm and the 5 cm permeation tubes. The data indicates an increase in
analyzer response of 1-2% as the purge flow rate was increased from 5
cc/minute to 50 cc/minute. Analyzer response remained constant at purge
flow rates above 50 cc/minute regardless of tube length.
The effect of varying the permeation chamber position was to create an
abrupt transitory disturbance within the chamber with a resulting change in
S02 concentration observed at the analyzer. The magnitude of the transitory
change in concentration ranged from 10-25% and appeared to depend on the
position of the tube within the chamber prior to the tilt. The disturbance
in the SCL concentration persisted for about 15-20 minutes with a 5 cc/
minute purge flow rate and for about 1 minute with a 100 cc/minute purge
flow rate. The equilibrium S0? concentration remained constant regardless
of the chamber position as the data in Table 14 indicates. Thus, the
reservoiring of SO- within the chamber would not appear to be a significant
source of error even at a purge flow rate of 5 cc/minute.
The data obtained in regard to tube length are anomalous. Analyzer re-
sponse increased 5% after the exhange of a 5 cm tube for a 2 cm tube. A 4%
62
-------
TABLE 14. EFFECT OF PERMEATION CHAMBER FLOW RATE ON SIGNAL RESPONSE
A.
FLOW
CC/MIN
5.0
10.0
25.0
50.0
100.0
B.
5.0
10.0
25.0
50.0
100.0
recheck
5.0
2.0 cm permeation
OVEN
POSITION
horizontal
vertical
horizontal
horizontal
vertical
horizontal
horizontal
vertical
horizontal
horizontal
vertical
horizontal
horizontal
vertical
horizontal
5.0 cm permeation
horizontal
vertical
horizontal
horizontal
vertical
horizontal
horizontal
vertical
horizontal
horizontal
vertical
horizontal
horizontal
vertical
horizontal
horizontal
tube
OBSERVED,
PPM
.306
.310
.312
.314
.314
.314
.317
.317
.317
.320
.320
.319
.320
.320
.320
tube
.330
.330
.328
.328
.330
.333
.339
.338
.336
.335
.335
.335
.327
.335
.335
.328
OVEN
THERMISTOR(V)
.549
.549
.549
.549
.549
.549
.549
.549
.549
.549
.549
.549
.549
.549
.549
.551
.551
.551
.550
.550
.550
.550
.550
.550
.550
.550
.550
.550
.550
.550
TEMPERATURE
(30.00°C)
(30.00°C
(30.00°C)
(30.00°C)
(30.00°C)
(30.00°C)
(30.00°C)
(30.00°C)
(30.00°C)
(30.00°C)
(30.00°C)
(30.00°C)
(30.00°C)
(30.00°C)
(30.00°C)
(29.92°C)
(29.92°C)
(29.92°C)
(29.96°C)
(29.96°C)
(29.96°C)
(29.96°C)
(29.96°C)
(29.96°C)
(29.96°C)
(29.96°C)
(29.96°C)
(29.96°C)
(29.96°C)
(29.96°C)
BENDIX °C
30.00
30.00
30.00
30.00
30.00
30.00
30.00
30.00
30.00
30.00
30.00
30.00
30.00
30.00
30.00
30.01
30.01
30.01
30.00
30.00
30.00
30.00
30.00
30.00
30.00
30.00
30.00
30.00
30.00
30.00
(continued)
63
-------
TABLE 14 (continued)
C. 10.0 cm permeation tube
FLOW
CC/MIN
5.0
10.0
25.0
50.0
100.0
OVEN
POSITION
horizontal
vertical
horizontal
horizontal
vertical
horizontal
horizontal
vertical
horizontal
horizontal
vertical
horizontal
horizontal
vertical
horizontal
OBSERVED,
PPM
.343
.345
.346
.345
.345
.343
.348
.346
.346
.346
.346
.344
.345
.346
.346
OVEN
THERMISTOR(V)
.549
.549
.549
.549
.549
.549
.549
.549
.549
.549
.549
.549
.549
.549
.549
TEMPERATURE
(30.00°C)
(30.00°C)
(30.00°C)
(30.00°C)
(30.00°C)
(30.00°C)
(30.00°C)
(30.00°C)
(30.00°C)
(30.00°C)
(30.00°C)
(30.00°C)
(30.00°C)
(30.00°C)
(30.00°C)
BENDIX °C
30.00
30.00
30.00
30.00
30.00
30.00
30.00
30.00
30.00
30.00
30.00
30.00
30.00
30.00
30.00
64
-------
TABLE 15. EFFECT OF S0£ PERMEATION TUBE LENGTH
2.0 cm Tube
FLOW OVER
PERMEATION
TUBE
CC/MIN
5.0
10.0
25.0
50.0
100.0
(NBS 29-99)
S0?
REPORTED,
PPM
.309
.314
.317
.320
.320
PERMEATION OVEN TEMPERATURE
THERMISTOR, V
.549
.549
.549
.549 (
.549 (
30.00°C)
30.00°C)
30.00°C)
30.00°C)
30.00°C)
BENDIX
30.
30.
30.
30.
30.
°C
00
00
00
00
00
AVERAGE
.316
5.0 cm Tube (NBS 27-12)
5.0
10.0
25.0
50.0
100.0
AVERAGE
.329
.330
.338
.335
.332
.333
.551
.550
.550
.550
.550
(29.92°C)
(29.96°C)
(29.96°C)
(29.96°C)
(29.96°C)
30.00
30.00
30.00
30.00
30.00
10.0 cm Tube (NBS 27-13)
5.0
10.0
25.0
50.0
100.0
AVERAGE
.345
.344
.347
.345
.346
.345
.549
.549
.549
.549
,549
(30.00°C)
(30.00°C)
(30.00°C)
30.00°C)
30.00°C)
30.00
30.00
30.00
30.00
30.00
Repeat 2.0 cm Tube (NBS 35-16)
5.0 .319
,551
(29.92°C)
30.00
65
-------
o
oo
LLJ
IE
O
•z.
I— I
CO
UJ
UJ
D-
oo
.MOVE CHAMBER FROM
VERTICAL TO HORIZONTAL
MOVE CHAMBER FROM
HORIZONTAL TO VERTICAL
5.0 cm SO^ Permeation Tube
5 cc/minute purge flow rate
FIGURE 25. TYPICAL STRIP CHART TRACE, S02 STUDY
66
FULL SCALE
-------
TABLE 16. EFFECT OF COOLING ON MODIFIED BENDIX 886IP CALIBRATOR
TIME
1300
1315
1330
1345
1400
1415
1430
1445
1500
Mean
SD
1515
1530
1545
1600
1615
1630
1645
1700
Mean
SD
SO,
OBSERVED,
PPM
.317
.319
.318
.321
.318
.322
.317
.319
.320
.319
.002
.329
.335
.336
.334
.334
.331
.330
.330
.332
.003
5 CC/MIN. PURGE FLOW
ENVIRONMENTAL SULFUR OVEN
CHAMBER T°C THERMISTOR(V)
22.1
23.8
23.2
23.3
23.3
23.8
23.3
23.0
22.8
10.0
9.0
8.0
8.0
8.0
8.0
8.0
8.0
-
-
.551
.551
.551
.550
.550
.551
.552
.557
.561
.564
.566
.567
.568
.568
-
-
(29.92°C)
(29.92°C)
(29.92°C)
(29.96°C)
(29.96°C)
(29.92°C)
(29.87°C)
(29.63°C)
(29.45°C)
(29.28°C)
(29.18°C)
(29.14°C)
(29.08°C)
(29.08°C)
BENDIX °C
-
-
30.00
30.00
30.00
30.00
30.00
30.00
30.00
30.00
30.05
30.05
30.05
30.05
30.05
30.05
67
-------
TABLE 17. EFFECT OF HEATING ON MODIFIED BENDIX 8861 CALIBRATOR
5 CC/MIN. PURGE FLOW
TRIAL 1
TIME
1000
1030
1300
1330
Mean
SD
1400
1415
1430
1445
1500
1515
1530
1545
1600
Mean
SD
0845
0900
0915
0930
0945
1000
1015
1030
Mean
SD
1045
1100
1115
1130
1145
1200
1215
1230
Mean
SD
S0?
OBSERVED,
PPM
.323
.321
.322
.321
.322
.001
.328
.325
.328
.327
.327
.318
.328
.327
.327
.326
.003
.340
.341
.341
.343
.342
.341
.337
.338
.340
.002
.336
.337
.337
.339
.338
.338
.337
.334
.337
.002
ENVIRONMENTAL
SULFUR OVEN
CHAMBER T°C THERMISTOR
25.0
24.1
24.6
24.4
38.9
36.2
41.8
39.0
37.8
37.8
37.7
38.2
38.1
23.7
23.9
24.1
24.1
23.9
24.1
24.0
23.9
32.0
33.0
33.4
33.4
33.6
32.5
32.3
32.1
.548
.548
.548
.548
.545
.541
.540
.538
.538
.538
.538
.538
.538
TRIAL 2
.550
.549
.549
.549
.549
.549
.549
.549
.548
.547
.545
.544
.543
.543
.543
.543
(30.05°C)
(30.05°C)
(30.05°C)
(30.05°C)
(30.20°C)
(30.40°C)
(30.45°C)
(30.55°C)
(30.55°C)
(30.55°C)
(30.55°C)
(30.55°C)
(30.55°C)
(29.96°C)
(30.00°C)
(30.00°C)
(30.00°C)
(30.00°C)
(30.00°C)
(30.00°C)
(30.00°C)
(30.05°C)
(30.10°C)
(30.21°C)
(30.25°C)
(30.30°C)
(30.30°C)
(30.30°C)
(30.30°C)
BENDIX °C
30.00
30.00
30.00
30.00
29.95
29.95
29.95
29.95
29.95
29.95
29.95
29.95
29.95
30.00
30.00
30.00
30.00
30.00
30.00
30.00
30.00
30.00
30.00
30.00
30.00
30.00
30.00
30.00
30.00
68
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increase in analyzer response was observed following the exchange of a 10 cm
tube for the 5 cm tube. A recheck of the 2 cm tube agreed within 1%. The
time allowed for equilibration of the permeation tubes after exchange ranged
from 16 hours to two days.
Although the effect of permeation tube length on analyzer response
appears significant, conclusions do not seem warranted. Of necessity, due to
equipment limitations, the study period associated with the exchange and
equilibration of permeation tubes was two weeks in duration. The precision
of the measuring system over the two week period of time may be no better
than the magnitude of the apparent effect of permeation tube length on
analyzer response.
The data in Table 16 indicate an adverse effect of cooling on the
Bendix calibrator. The permeation tube chamber purge air temperature dropped
from the normal control temperature of 30.0°C to a low of 29.1°C as the
environmental chamber temperature decreased 15°C. The SO,, concentration
observed at the analyzer, however, increased. The reason for the increase
was not determined. The dilution air flow controlling orifices in the cal-
ibrator, normally thermostated, were observed to be operating below the
normal control temperature during the cooling test as indicated by contin-
uous heater operation. The dilution air mass flow meter, however, did not
indicate a change in dilution airflow.
The only effect of heating on the Bendix calibrator that was observed
was a rise in the purge air temperature from the normal control temperature
of 30.0°C to 30.6°C indicating an inefficiency in the thermoelectric cooling
assembly control. No significant change in S02 concentration was observed
at the analyzer during the course of the test. Trial 1 and trial 2 were
conducted under seemingly identical conditions several days apart. The
only variable known to have changed was the air scrubber (Ascarite was
changed). The difference in analyzer response at room temperature of 5%
between the two trials would appear to be an estimation of the precision of
the measuring system employed.
During the course of this study, the most significant problem observed
in regard to the routine operation of the Bendix calibrator was the difficulty
69
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in obtaining a complete seal of the permeation tube chamber after the
replacement of a permeation tube. Even a relatively minor leak was observed
to be of consequence with a purge airflow rate of only 5 cc/minute. The
problem was aggravated at high dilution airflow rates where significant
back pressure forced additional leakage. A new permeation tube holder
designed to eliminate this problem and to provide adequate purge air temper-
ature control was designed, fabricated, and installed. A description of the
holder is included in Appendix B.
The study described in this section was performed during the final
phase of the Task Order. The modified calibrator resulted from experience
gained during the course of the study. It is apparent from the data
obtained that the Bendix calibration system, as originally supplied by the
vendor, may have had limitations in routine operation, particularly in
regard to audit work performed at low ambient temperatures.
70
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APPENDIX A
AUDIT PROCEDURES FOR RAPS INSTRUMENT SYSTEMS
71
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CONTENTS
Figures 73
Tables 73
A.I Introduction 74
A.1.1 Preparation of Bendix Calibration/Audit Equipment 74
A.2 Calibration of Winnebago Instrumentation 81
A.2.1 Calibration of the Tracor Model 270HA Atmospheric
Sulfur Analyzer 81
A.2.2 Calibration of the Monitor Labs Model 8440 Oxides
on Nitrogen Analyzer 84
A.2.2.1 Ozone Generator 87
A.2.3 Bendix Ozone Analyzer 89
A.2.4 Calibration of MRI 1561 Nephelometer 90
A.3 Audit Procedures 92
A.3.1 Sulfur Analyzer Audits 92
A.3.2 Oxides of Nitrogen Analyzer Audit 92
A.3.3 Ozone Analyzer Audit 94
A.3.4 MRI 1561 Nephelometer Audit 96
A.3.5 Audit Procedure for Atmospheric Methane, Carbon
Monoxide and Total Hydrocarbons 96
A.4 Air Management 98
72
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FIGURES
Number Page
A.l Bendix 8861D Flow Diagram 75
A.2 Bendix 8861P Flow Diagram 76
A.3 Typical Calibration Curve for Bendix 8861D 78
A.4 Typical Interconnections for Introduction of Calibration 82
Gas into Instrument to be Calibrated or Audited
A.5 Conversion Efficiency Determination 94
TABLES
Number Page
A.I Sulfur Dioxide Calibration: Typical Bendix 8861
Settings 83
A.2 Settings for NOX Analyzer 85
A.3 Oxides of Nitrogen Calibration: Typical Bendix
8861D Settings 86
A.4 Sample Tabulation for a NO - 0., Titration 88
A.5 Values for Ozone Calibration 89
A.6 Sample Table to be Used in the NOX - NO Audit 93
A.7 Settings to use on Bendix Calibrator to Produce
Various Ozone Concentrations 95
A.8 Values for Ozone Audit at High Lamp Output 95
73
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A.I INTRODUCTION
The following procedures were established and tested during the initial
stages of work on Task Order 106. The procedures are presented in logical
sequence and related to both routine audit procedures, as well as the routine
calibration work performed, utilizing the pollutant monitoring equipment
aboard the Winnebago van.
A.1.1 PREPARATION OF BENDIX CALIBRATION/AUDIT EQUIPMENT
1. Calibration curves used to read air and gas flows from the Bendix
instruments must be developed as follows (reference Figures A.I and A.2):
a) Break the connection at the brass "T" upstream of pressure regu-
lator PR-2 on the 8861D and cap off the side of the "T" leading
to the instrument filter.
b) Attach a zero air cylinder to the 8861D at the "clean air" port
using a length of 1/4" tubing. Set the cylinder regulator
delivery pressure to 40 PSI.
c) Starting with pressure regulators PR-1 and PR-2 closed and
orifice No. 2, 3, 4, 5 closed, connect the 8861D "out" port to
a 1000 cc bubble tube.
d) Open PR-2 to 10% of gauge as monitored by pressure gauge P2 and
measure the air flow rate at the "out" port using the bubble
tube. Repeat this procedure at 20%, 30%, etc., to 100% of
gauge.
e) Repeat d) above with orifice No. 1 and No. 2 open.
f) Repeat d) above with orifice No. 1 and No. 3 open.
g) Repeat for the remaining orifices and all combinations of
orifices, i.e., finish with 1+2+3+4+5 for maximum flow through
74
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5
5
o 5
2
O
o
00
00
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75
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the 8861 D.
h) Repeat the above procedure and calibrate the nitric oxide capil-
lary using nitrogen entering the "NO Inlet". Flow from the
capillary to a 10 cc bubble tube can be taken at the NO "pull-
to-test" valve.
i) Repeat the above procedure and calibrate the capillary upstream
of 8861P permeation oven. Close VI toggle valve (off position),
introduce zero air into the "N,," port and with V2 closed and V3
open, attach a 10 cc bubble tube to the 8861 P outlet port for
the flow calibration.
j) After converting all of the flows to cc/minute for each of the
10% gauge increments, the flows must be corrected to standard
temperature of 0°C and standard pressure of 760 mm Hg by multi-
plying each reading by a factor. The correction factor is
derived as follows:
23.5°C = temperature in lab at time of calibration
746.3 mm mercury, barometric pressure in lab at time of calibra-
tion.
Correction _ _ 273 _ Bar. Press, in mm Hg
Factor 273 + Ambient Temperature 760
273 746.3
273 + 23.5 760
Graphs are now prepared by plotting "Gauge Reading - % of scale" as the
ordinate and "cc/minute" along the abscissa. This will facilitate reading
any flow within the range of the capillary or orifice under study (see
Figure A. 3).
2. With Bendix 8861 P set on "stand-by", the internal air pump is opera-
tive and keeps a flow of air through the permeation oven. If this pump is
shut off, twelve to twenty-four hours are required to re-establish equilib-
rium condition within the permeation oven. Assuming an equilibrium condition
with the permeation oven temperature at 30°C +_ 0.02°C (running for twelve to
77
-------
90 -
80 -
70 -
60 -
' 50 -
CJ3
a:
UJ
C3
40 -
30 -
20 -
10 -
4000 4500 5000 5500 6000 6500 7000 7500 8000
cc/tnin.
Bendix 8861D Orifice 2+3+4+5
FIGURE A.3 TYPICAL CALIBRATION CURVE FOR BENDIX 8861D
78
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twenty-four hours on 115 VAC with power switch in ON position, VI toggle
valve in OFF position and PR-1 pressure regulator set to 100% of scale on
the 0-15 psig) prepare the 8861D for operation.
3. Turn the power switch on the Bendix 8861D to the ON position, turn
OFF V3, 4, 5, 6 (corresponding to orifices 2, 3, 4 and 5). Connect a 1/4"
Teflon line between the 8861D "clean air" port and the N2 inlet on the 8861 P.
The 8861D is now providing zero air to the 8861P where it will flow through
the 5 cc/min capillary and purge the permeation oven. At this point, the
permeation tube oven effluent will exit either through the "vent" or through
the "outlet" depending on the settings on V2 and V3 (V3 open, V2 closed,
gas goes to "outlet". V3 closed, V2 open, gas goes through scrubber to
"vent").
The Bendix 8861D can produce air of quality adequate for conducting all
of the standard audits except for the Beckman 6800. Scrubbed air of good
quality is possible if scrubbers are installed as follows: remove the "U"
tube connector between the air surge tank and the particulate filter. At
the outlet of the surge tank install a short line leading to a "Drierite"
scrubber filled with indicating Drierite. In series with the Driertie
scrubber install a second Drierite column charged with cocoanut shell
charcoal, 6-14 mesh. The outlet from the charcoal scrubber is attached to
the Bendix particulate filter.
4. Before calibrations or audits actually begin it is necessary to
point out certain pitfalls which must be avoided.
a) Standards. The NO gas cylinders used in this work must be
certified as to exact composition, i.e., NBS or directly trace-
able to an NBS cylinder. For the CO, CH4, THC audits and
calibrations, cylinders of known composition will be used and
again, these must be certified as traceable to NBS or certified
as to exact composition by RTP. Sulfur dioxide permeation tubes
purchased directly from NBS will be used in the Bendix 8861P
and the permeation oven will be operated at 30°C +_ .02°C to
insure an accurate output of S02.
79
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Since the FID response of most hydrocarbon analyzers is sensi-
tive to oxygen concentration, it is necessary for zero air and
matrix air (in the standard cylinders) to have the same oxygen
content as ambient air. Similarly, for TS analyses employing
flame photometric detectors, the matrix air must have the same
COp content as ambient air.
b) Flow rates. Every instrument audited has a specific sample flow
rate and it is necessary to insure that the flow of calibration
gas (from the Bendix 8861D) exceeds the analyzer demand. Good
practice dictates a procedure whereby a rotameter is used to
measure the sample flow of any instrument when the demand is
unknown. The flow as measured by the rotameter must then be
exceeded when preparing calibration gas to avoid taking in
ambient air along with the calibration/audit gas entering the
sample port of the instrument under test.
c) Materials used. Since SO^ and (L both are quite reactive it is
mandatory to always convey these gases in glass and/or Teflon.
Span gases containing nitric oxide, carbon monoxide, methane,
or other hydrocarbons are less critical but nevertheless con-
veyed in Teflon tubing.
d) Distinction between "audit" and "calibration". When the opera-
tor is instructed to calibrate an instrument, known gas compo-
sitions are introduced and the instrument is adjusted to respond
in accordance with the known gas composition. This is accom-
plished in accordance with the instructions given in the manual
for that instrument and involves changing instrument dial
settings, potentiometer adjustments and any other adjustment
necessary to cause the instrument to read the same value as
the gas being introduced. An audit on the other hand involves
absolutely no instrument adjustment. A known composition gas
is introduced and the instrument read-out is taken and recorded.
80
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A.2 CALIBRATION OF WINNEBAGO INSTRUMENTATION
The Winnebago van is equipped with a full complement of air quality
analyzers for use in preparation of the Bendix 8861 calibration system for
audit activities and for use in running "side-by-side" field comparisons
in proximity to existing air quality monitoring sites. The following pro-
cedures relate to the calibration of this instrumentation for the above
mentioned purposes.
A.2.1 CALIBRATION OF THE TRACOR MODEL 270HA ATMOSPHERIC SULFUR ANALYZER
Figure A.4 depicts the interconnection described in the following para-
graphs and should be referenced for clarity.
1. Connect a 1/4" Teflon line between 8861D "out" port and the normally
open port of the input solenoid valve of the Tracer. Provide a "T" connec-
tion or a glass manifold in this line to vent excess gas delivered by the
8861D.
2. Provide zero air input to Tracer as follows:
a) A 1/4" Teflon line should be connected between the 8861D "out"
and the Tracer input (through a "T" or manifold as previously
described). With the 8861D operating, adjust pressure gauge
P-2 to 50% with valve (orifice) 5 in (M position. Zero air at
the rate of 3000 cc/min is now leaving the 8861D.
b) Set a DVM on 0-5 volt range.
c) Connect the DVM as follows: one set of leads to "TS low" and
"gnd" and another set of leads to "S02 low" and "gnd". These
connections are on the rear of the Tracer on the terminal
strips marked "TB2". The two sets of leads are alternately
plugged into the DVM to read sulfur dioxide or total sulfur.
81
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Z
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O GC.
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3. Allow the analyzer to sample zero air for fifteen minutes and then
take a voltage reading. Record sulfur dioxide and total sulfur voltages on
each channel.
4. Connect a short length of 1/8" OD Teflon tubing between the 8861P
"outlet" and the 8861D HpS/SO,, inlet. Sulfur dioxide gas is now entering
the 8861D so that it may be diluted to the desired concentration.
5. Run a calibration recording voltages as explained above and using
the following typical table (Table A.I) to obtain the desired dilutions.
TABLE A.I SULFUR DIOXIDE CALIBRATION; TYPICAL BENDIX 8861 SETTINGS
Dilution F * +
Concentration
Desired (PPB)**
0
50
60
70
90
100
150
190
300
500
700
900
-
7220 H
6015 H
5155 H
4008 -
3607 J
2402 H
1895 H
1197 H
715 H
509 H
395 H
FP
i- 7
H 7
i- 7
h 7
i- 7
h 7
H 7
h 7
H 7
H 7
i- 7
Orifice
Used
1,
1,
1,
1,
1,
1,
1,
1,
1
1
1
2, 3, 4, 5
2, 3, 4, 5
2, 3, 4, 5
4, 5
4, 5
4
3
2
Percent Station
of Voltage
Gauge S02 TS
-
69
43
26
25
16
30.5
72
14.5
91
35
12
* Where F = cc/minute of S02 air delivered by 8861P
(through permeation tube oven at 30.00°C) and
Fd = cc/minute of air delivered by the 8861D diluter.
** Calculated using NBS permeation tube 21-71 with a permeation rate
of .946 micrograms/minute at 30°C.
The calibration is run by selecting four or more points from the table
and recording the voltages at each of the selected dilution settings. A
graph is then plotted to determine response linearity.
83
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6. In the event additional points are required, they are calculated
as follows:
r = PR x K
ppm - Fp + Fd
Where C = desired concentration in parts per million
PR = permeation rate in ng/min (Ref. to oven temperature.)
K (Ref. to 0°C and 760 mm Hg) - Mo1ecu1ar ^ perm. gas
(22Al of an ideal gas = 1.00 mole at 0°C, 760 mm Hg)
F = cc/minute from the 8861P permeation device
F, = cc/minute from the 8861D dilution device
EXAMPLE: The 2.0 cm S02 permeation tube is NBS certified to deliver 946
ng/min at 30°C. To calculate the dilution air flow rate corre-
sponding to a desired gas concentration:
Flow Rate <946> < TT >
(cc/min) " Desired Concentration
ppm
Desired flow rates are read off the calibration curves developed for
the orifices in these instruments. These curves are kept with the service
manuals.
A.2.2 CALIBRATION OF THE MONITOR LABS MODEL 8440 OXIDES OF NITROGEN ANALYZER
1. Inspect rear panel of the analyzer unit and the sample conditioning
unit and check the following items:
a) Drier connected to brass air inlet
b) Teflon NO line connected between modules
c) Teflon NOX line connected between modules
d) Teflon ozone line connected between modules
e) Teflon sample inlet line connected to glass sample manifold
(see Figure A.4).
84
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f) Glass sample manifold should be connected to the 8861D output
2. Connect the nitric oxide source gas (typically 100 ppm NO in
nitrogen) to 8861D NO inlet.
3. Turn on the main power and the ozone generator power on NO,,
analyzer.
4. Adjust vacuum gauge to 20 inches. This results in rotometer flows
as follows:
NOX - between 150-200 cc/min
NO - between 150-200 cc/min
Ozone - between 100-150 cc/min
5. Connect a DVM to the DVM terminal blocks on the rear of the instru-
ment. Use the NO terminals.
6. Connect a 0-1 volt recorder to the terminal posts on the front of
the instrument and adjust instrument settings as shown in Table A.2.
TABLE A.2 SETTINGS FOR NOX ANALYZER
Channel Sec.
NOY 20
A
NO 20
Range
2
2
Vac. Flow
20 175
225
Ozone = 100
7. Start the Bendix diluter and adjust for 3000 cc/min zero air.
Allow the analyzer to sample the zero air and then adjust both NO and NO,,
channels using the respective zero potentiometers to give zero volts on the
DVM (or a slight positive off-set if this is desirable).
8. Introduce each span gas concentration in turn selecting points and
conditions as shown in Table A.3.
85
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TABLE A.3 OXIDES OF NITROGEN CALIBRATION: TYPICAL BENDIX 8861D SETTINGS
Dilution
Concentration
Desired (ppm)
0.45
0.35
0.25
0.20
0.15
0.05
FP * Fd *
467
601
841
1052
1402
4208
Orifice
Used
1
1
2
2
3
3, 4, 5
Percent of
Gauge PI
38.5
38.5
38.5
38.5
38.5
38.5
FP
cc/min
2.0
2.0
2.0
2.0
2.0
2.0
?2 Gauge
Setting
34
72
24.5
50.5
37.5
22.5
* Where F = cc/min of NO from the cylinder
F. = cc/min of air delivered through the 8861 D orifices
Calculation of other points can be accomplished using the following
equations:
(NO cone, in cylinder, ppm) x F
- = NO concentration, ppm
For example, if a final concentration of .05 ppm NO,, is desired, and
the concentration of NO in the cylinder is known to be 105.2 ppm, we
can fix F at 2 cc/min by setting P^ to 38.5% of gauge. F^ can be
determined from the above equation or:
Since F is set at 2 cc/min, Fd = 4208 cc/min. This can be achieved
by setting P« to 22.5% and opening orifice 3, 4 and 5.
86
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9. Determination of efficiency of NCL to NO converter. Proceed as
follows:
a) Starting with both channels properly zeroed, introduce diluted
NO to the calibrated analyzer to read 1.5 - 2.0 ppm NO.
b) When equilibrium is achieved, observe that equal response
obtained on the NO and NOX channels.
c) Reverse the channels to check for NO purity.
d) Turn on the 03 generator within the Bendix 8861D. Wait 10
minutes.
e) Adjust the Bendix 03 generator so NO reading is reduced to 50%
of original reading. Record stable NO and NOY values. The drop
A
in NO concentration is equal to the concentration of NOp formed
in accordance with the reaction equation
NO + 03 = N02 + 02
f) Calculate efficiency
MX
E = 1 -
(Orig.) - NOX (Final)
NO (Orig.) - NO (Final)
A.2.2.1 Ozone Generator
x 100
Immediately following the calibration of the oxides of nitrogen analyzer
and prior to the calibration of the ozone analyzer, the ozone generator with-
in the Bendix 8861D should be calibrated. To perform a gas phase titration
of nitric oxide within the Bendix 8861D, it is first necessary to establish
an equilibrium concentration of nitric oxide. This may be done using the
techniques described in section A.2.2 in regard to the calibration of the
oxides of nitrogen analyzer. The nitric oxide channel of the analyzer then
serves to monitor the results of the titration occurring within the Bendix
8861D. All that is required to perform the titration is to turn on the
ozone generator in the calibrator. Air flowing through orifice 1 will pass
over the ultraviolet lamp, undergo irradiation, and meet with nitric oxide
in a glass reaction chamber. The reacted mixture leaves the reaction chamber
87
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and is diluted in the mixing chamber. The residual nitric oxide concentra-
tion after ozone titration is then observed using the nitric oxide channel
of the analyzer. A step by step example is as follows:
Proceed initially as explained in section A.2.2 to prepare the Bendix
8861D and a Monitor Labs 8440 oxides of nitrogen analyzer. Establish zero
air flow either from the Bendix calibrator or from a cylinder to the sampling
manifold and subsequently to the sample inlet port of the 8440. Zero the
analyzer using the zero potentiometer. Establish an initial nitric oxide
concentration of 0.8 ppm. A typical set of conditions using a cylinder
certified at 105.2 ppm NO is presented in Table A.4.
TABLE A.4 SAMPLE TABULATION FOR A NO - 03 TITRATION
Desired p
Cone. , ppm 1
0.80 80%
Fp P2 Fd Orifice
4.0 49% 522 1
F + Fd = 526 cc/minute
Output,
NO
.800
Volts
NOV
A
.800
Once a stable trace is established on the recorder, the ozone generator
is set to Range 500, Set Point 440 and the lamp is turned on. After a short
time the NO channel will show a sharp decrease as ozone reacts with the NO.
After ozone addition the nitric oxide concentration is measured again by
monitoring the NO channel of the analyzer. In this particular example, the
NO channel decreased to 0.400 volts. The ozone output is now calculated
using the above information.
0.800 (original voltage before 0^ addition)
0.400 (final voltage after ozone lamp was started)
0.400 difference
On the analyzer used the slope was 1.00 ppm/volt
0.400 x 1.00 = 0.400 ppm decrease in NO concentration
Since NO reacts with 03 1:1 stoichiometrically, this means 0.400 ppm
ozone reacted in the diluted gas stream. To convert this figure to the
88
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undiluted concentration delivered from the ozone lamp source we use
microliters of ozone/min = ppm ozone x dilution air, liters/min
or .400 x .526 = 0.2104
The lamp is now calibrated at an air flow of 0.526 liters/minute and is
producing 0.2104 microliters of ozone per minute at standard temperature and
pressure.
A.2.3 BENDIX OZONE ANALYZER
Once the ozone generator in the Bendix 8861D has been calibrated, an
ozone analyzer calibration may be performed. In this case the pressure
setting on the capillary (No. 1) is not changed to insure a constant ozone
production as dilution air is varied. Dilution air is added in this case
only by using additional capillaries. To get the second point for the
calibration we now open capillary No. 2 and readjust P2 to 49%. The table
below indicates the capillaries used and the resulting concentration.
After each additional capillary is opened, P2 must be readjusted to 49% to
maintain a known standard air flow over the ozone lamp. Typical flow
settings are shown in Table A.5.
TABLE A.5 VALUES FOR OZONE CALIBRATION
Ozone
Desired
Cone, ppm
0.40
0.20
0.10
0.083
0.040
Orifice
1
1 + 2
1 + 3
1 + 4
1 + 2 + 3 + 4
Dilution Air
LPM
0.526
1.055
2.104
2.550
5.320
P2
49%
49%
49%
49%
49%
sample calculation:
lrr = 0<400 ppm ozone
89
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After the flow conditions have been established, perform the following
steps to complete the five point calibration of the ozone analyzer.
1. Attach the Teflon output line from the Bendix 8861D to the sample
input of the Bendix ozone monitor via a "T" or a glass manifold.
2. With power switch to "on" position (allow 120 minutes for warm-up),
adjust ethylene flow to 25 cc/minute.
3. Set mode selector to ambient, time constant to 10 seconds, and
range selector to 0.5 ppm.
4. The terminal block on the rear of the instrument may be used to
display a DVM response to the calibration gas.
5. Select each point in turn as illustrated in Table A.5 to complete a
five point calibration on the ozone instrument.
A.2.4 CALIBRATION OF MRI 1561 NEPHELOMETER
All pots and test points referred to in this procedure are located on
the electronics board on the inside of the instrument front door. In all
cases the voltages should be read with a digital volt meter connected to the
red and black terminals located on the righthand side of the instrument.
The meter on the face of the instrument should be used only as a rough in-
dication of instrument behavior. In RAMS stations the data acquisition
system digital display may be used with the analog signal appearing on
channel 37.
The following steps should be followed in sequence.
1. Unhook the inlet hose and plug the intake.
2. Move the "air - operate - Freon" switch to the "air" position.
3. Plug the lower outlet and wait at least 15 minutes or until meter
reading and/or voltage output are steady.
4. Readout should be 0.00 VDC+ .03; if not, adjust R-42 (background)
for proper reading.
5. Connect a jumper from TP-1 to TP-8 on the electronic board. This
should cause the light to go out. Readout should slowly return to 0.00 +_
90
-------
.03 VDC. If not, adjust R-61 (zero) for correct reading.
6. Repeat steps 5 and 6 until interaction is out of circuit.
7. Place "air - operate - Freon" switch in the "Freon" positon.
Unhook the tubing coming from the top of the Y shaped tube fitting above the
small clean air pump. Insert the delivery tube from the Freon bottle in the
tubing and turn the valve on top of the bottle on. A flow-limiting orifice
is in this valve so that proper flow occurs when the valve is fully open.
8. After readout becomes steady (15 minutes or more) the output voltage
should be 1.00 +_ .03 VDC. If not, adjust R-64 (Freon) for correct reading.
9. Connect jumper from TP-1 to TP-9. Readout should slowly rise to
4.00 +_ .25 VDC. If not, adjust R-57 (calibrate) for correct reading.
10. Remove jumper and observe that readout returns to 1.00 +_ .03 VDC.
If not, adjust R-64 (Freon) for correct reading.
11. Repeat steps 9 and 10 until there is no interaction.
12. Unit is calibrated. Unplug air inlet and outlet, remove Freon con-
nection and reconnect tubing to the top of the Y shaped tube fitting in the
clean air system, reconnect inlet hose at top of instrument and move "air -
operate - Freon" switch to "operate" position.
91
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A.3 AUDIT PROCEDURES
The audit work performed during the course of this study was in most
part performed with the Bendix 8861 portable calibrator. Additional audit
work was performed with standard gas cylinders introduced directly to the
analyzer audited. All such procedures are outlined below.
A.3.1 SULFUR ANALYZER AUDITS
Establish a flow of zero air from the manifold on the 8861D to the
sample air inlet of the sulfur instrument under audit. The flow rate used
is determined by the instrument under test. For example, an instrument such
as the Sign-X uses 2.5 LPM while a Tracor uses only 0.360 LPM. Choose an
air flow from the calibrator in excess of the demand of the instrument under
audit. Once a zero air flow is established and the instrument output
voltage is recorded, introduce the output from the 8861P into the dilution
air and establish the highest sulfur concentration to be used in the audit.
For example, when auditing a Tracor, set up to deliver 395 + 7 cc of zero
air. (The 8861D is set at 12% of gauge (P2) and orifice 1 is open as per
Table A.I.) Connect the 1/8" Teflon line (the permeation oven output) to
the input side of the dilution chamber on the 8861D. Sulfur dioxide gas is
now being mixed in the dilution air in the proper proportions to give 0.900
ppm S0?. After conditions have stabilized, read the voltage- corresponding to
0.900 ppm S02. Next, using only orifice No. 1, set P2 to 35% of gauge.
The concentration of S02 is now at 0.700 ppm. Continue to add more dilution
air as indicated in Table A.I until four or more points (plus zero air) have
been established.
A.3.2 OXIDES OF NITROGEN ANALYZER AUDIT
Use a rotameter on the input of the instrument to check total sample
flow which should be about 500 cc/minute.
92
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Calculate the desired gas concentrations to be used to audit the
instrument using the following equation:
(NO cone, in Tank, ppm) x (cc/min thru V,) ..n . ..
(cc/min thru VJ) + fcc/min thru Vg) ] = N0 concentration in ppm
A table should be developed and used throughout this audit. An example
of a calculation and an appropriate table is shown in Table A.6.
TABLE A.6 SAMPLE TABLE TO BE USED IN THE NOX - NO AUDIT
Desired
Cone, ppm
0.40
0.30
0.20
0.10
0.05
zero
cPJ
4.0
4.0
4.0
4.0
4.0
0
PI
% Gauge
80.5
80.5
80.5
80.5
80.5
0
P2
cc
910
1213
1820
3640
7280
7290
P2
% Gauge
33.0
75.0
81.0
24.5
88.0
88.0
Orifice
No.
1+2
1+2
1+3
1+4+5
1+2+3+4+5
1+2+3+4+5
NOY
AVolts
.808
.604
.390
.194
.094
.004
NO
Volts
.808
.600
.390
.193
.092
.002
Sample Calculation:
= 91° cc/min flow
(91.0 ppm) = cone, of NO in NBS supply tank
(4.0) = cc/minute flow thru capillary 1
(0.40) = desired ppm of NO for first audit point
The flow is established for the first point (0.40 ppm of NO) and after
the recorder indicates stable conditions the voltage is read on both channels.
Next, P2 is opened to 75% giving a flow of 1213 cc/minute. The NO concentra-
tion now flowing to the manifold is 0.30 ppm. Again, after conditions have
stabilized a voltage reading is taken after the last reading (0.05 ppm). The
NO tank is turned off and a zero air reading is taken.
The N0? converter in the oxides of nitrogen analyzer is challenged
during the course of the audit by the partial conversion of nitric oxide to
nitrogen dioxide prior to delivery to the analyzer audited. The results
obtained by monitoring the nitric oxide (NO) and the oxides of nitrogen
93
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(NOX) channels of the analyzer audited are used to determine the converter
efficiency. As a typical example, the following audit data obtained at
RAMS station 114 is presented.
NO
Auditor
Value
(ppm)
.450
ozone
added
.350
.250
.150
zero
Instrument
Reading
(volts)
4.8413
1.5258
3.7792
2.6635
1.6479
.0341
Instr.
Reading
(ppm)
.473
.146
.368
.258
.158
-.001
Auditor
Value
(ppm)
.450
ozone
added
.350
.250
.150
zero
Instrument
Reading
(volts)
4.8217
4.7998
3.7792
2.6684
1.6074
.0512
Instr.
Reading
(m-1
.483
.480
.377
.254
.163
-.001
N0/N02 CONVERTER EFFICIENCY: 99%
Converter Efficiency =
(ppm NOY, 0, off) - (ppm NOY, 0, on)
_ _ . . _
(ppm NO, 03 off) - (ppm NO, QS on)
inn
IUU
FIGURE A.5 CONVERSION EFFICIENCY DETERMINATION
The partial conversion of nitric oxide is achieved by energizing the
ozone generator within the Bendix auditor just after the establishment of
an equilibrium analyzer response to the first audit nitric oxide concentra-
tion delivered at .45 ppm (in this example). The equilibrium response after
ozone addition is recorded for both the NO channel and the NOX channel.
Conversion efficiency is then calculated as indicated in Figure A05.
A.3.3 OZONE ANALYZER AUDIT
Prior to the audit of every ozone analyzer, it is advisable to check the
output of the ozone source in the Bendix 8861D by performing a N0-0~ titra-
tion. A convenient time for this check will occur during the oxides of
nitrogen audit, if the monitoring station being audited is equipped with an
oxides of nitrogen analyzer. If it is not so equipped, the ozone source
should be checked before and after the audit using the Winnebago instrumen-
tation and the procedures described in section A.2.2.1. After verification
of the ozone generation rate, develop the conditions for the audit such as
94
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those indicated in Table A.7.
TABLE A.7 SETTINGS TO USE ON BENDIX CALIBRATOR
TO PRODUCE VARIOUS OZONE CONCENTRATIONS
Fixed conditions:
!i !^
80% 4.0
Des i red
Ozone
Cone, (ppm)*
0.400
0.200
0.138
0.100
0.083
0.040
P2 Orifice
49% 1
cc Air/mi n
used to dilute
NO supply
526
1055
1530
2104
2550
5320
Orifice used
develop desi
air flow
1
1, 2
1, 3
1, 2, 3
1, 4
1, 3, 4, 5
to
red
*Lamp at 440 set point, 500 range
The Bendix ozone lamp may be calibrated for a higher ozone output. This
becomes necessary whenever high sample flow rate instruments are to be
audited. For example, a Sign-X or a Dasibi uses a minimum of 2500 cc/minute.
This demand would only allow the use of the last two concentrations in the
above table. An alternate scheme is given below for high ozone outputs. In
this case, the lamp is at SET POINT = 500, RANGE = 1000.
TABLE A.8 VALUES FOR OZONE AUDIT AT HIGH LAMP OUTPUT
Ozone
Desired
Cone, ppm
0.2550
0.2158
0.1420
0.110
Orifice
1 + 5
1 + 2 + 4
1+4+5
1+2 + 3 + 4+5
Dilution Air
LPM
3.364
3.975
6.044
7.730
95
-------
After establishing the appropriate Bendix 8861 settings for the analyzer
under audit, introduce each point in turn and record the analyzer response.
A.3.4 MRI 1561 NEPHELOMETER AUDIT
A red and black binding post are located on the right hand side of this
instrument. Connect a DVM to these terminals. Do not use the meter on the
front cover to assess instrument behavior. Next, proceed as follows:
1. Unhook the inlet hose and plug the intake.
2. Move the "air - operate - Freon" switch to the "air" position.
3. Unplug the lower outlet and wait at least fifteen minutes after the
machine is turned on or until meter reading and/or voltage output are steady.
4. Readout should be 0.00 VDC +_ .03. Record this voltage.
5. Connect a jumper from TP-1 to TP-8 on the electronic board. Record
the voltage after it reaches a steady value. Remove jumper when step 5 is
complete.
6. Unhook the tubing coming from the top of the glass "T" above the
small clean air pump. Insert the delivery tube from the Freon-12 bottle in
the tubing and turn the valve on the top of the bottle on. A flow-limiting
orifice is in this valve, supplied by the vendor along with the bottle, so
that proper flow occurs when the valve is fully open.
7. After the readout becomes steady, record the voltage.
8. Connect a jumper from TP-1 to TP-9. Readout should rise slowly.
When it is steady, record the voltage.
9. Remove the jumper and record the voltage after it again stabilizes.
A.3.5 AUDIT PROCEDURE FOR ATMOSPHERIC METHANE, CARBON MONOXIDE AND TOTAL
HYDROCARBONS
Establish a flow of zero air from a tank of known purity as follows:
connect a 1/4" Teflon line to the tank and terminate this line with a "T".
One side of the "T" goes to the sample air inlet of the instrument under
test and the other side goes to a rotameter. The outlet valve on the tanks
is regulated so as to keep excess air flowing through the rotameter. If
96
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the demand of the instrument under test exceeds the regulated output of the
tank the rotameter reading will fall to zero and the instrument under test
will take in ambient air. After a voltage value is established for zero air,
replace the zero air tank with a tank containing a gas mixture of known
composition and obtain the analyzer response for the mixture.
As an alternate procedure, the audit standards are prepared in Teflon
bags. The bags are first purged and evacuated several times with zero air.
The bags are then filled with audit gas(es) and delivered for introduction
to the analyzer audited. Sampling in this case is directly from the bag to
the analyzer through the analyzer sample line with no external venting.
97
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A. 4 AIR MANAGEMENT
Because of the fact that the Bendix calibrator does not produce air of
quality adequate for all audits, it is frequently necessary to substitute
cylinder zero air. Depending upon whether the audit is performed at a RAMS
station using RAMS zero air, or at some other location, the choice of zero
air is somewhat determined by the pollutant under study. A comparison of
RAMS station zero air (No. 101 on 2/20/76) and Scott cylinder zero air
showed the following:
STATION AIR CYLINDER AIR
Analyzer Response, Analyzer Response,
ANALYZER Volts/ppm Volts/ppm
03 .0284/ .000 .0207/-.001
NO -.0056/-.002 .0402/ .002
NOX .0479/-.002 .0476/-.002
TS Low .0634/-.002 .1171/-.001
H2S Low .0284/-.002 .1134/ .000
S02 Low .0284/-.002 .0976/ .000
CO .1310/-.036 .1318/-.034
CH4 .1896/-.017 .0683/-.267
THC .2368/-.198 .2575/-.149
In general:
1) The Bendix auditor with charcoal scrubbers will furnish air of
sufficient quality to audit only the sulfur, NO, and ozone
analyzers.
2) Ultra pure cylinder air should be used for CH., CO, and THC.
The Bendix auditor is not capable of removing these gases from
ambient air. RAMS station zero air is generally of high
quality but depends on the efficient operation of a catalytic
oxidizer.
98
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APPENDIX B
MODIFIED BENDIX MODEL 8861 PORTABLE CALIBRATION SYSTEM
99
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CONTENTS
B.I Introduction 102
B.2 Modifications 103
B.2.1 Zero Air System 103
B.2.2 Flow Measuring System 103
B.2.3 Permeation Tube Chamber 115
B.2.4 Monitoring Console 118
B.3 Instructions for Use of the Modified 8861 123
100
-------
FIGURES
Number Page
B.I Modified Bendix 8861P Flow Diagram 104
B.2 Modified Bendix 8861D Flow Diagram 105
B.3 MFM #1 108
B.4 MFM #2 (NO) 110
B.5 MFM #3 (Ozone) 112
B.6 MFM #4 (Sulfur) 114
B.7 Permeation Tube Holder 116
B.8 Modified Bendix 8861P Permeation Tube Holder 117
B.9 Calibration of Fenwal GB41P2 Thermistor 119
B.10 Wiring Diagram 122
TABLES
Number Page
B.I Mass Flow Meter No. 1 (Main Dilution Air) 107
B.2 Mass Flow Meter No. 2 (NO) 109
B.3 Mass Flow Meter No. 3 (Ozone) 111
B.4 Mass Flow Meter No. 4 (S02) 113
B.5 Pin Assignments - Mass Flow Meters 120
101
-------
B.I INTRODUCTION
During the course of RAMS-RAPS audit work involving the routine use
of the Bench'x Model 8861 portable calibration system, a number of problem
areas were noted. Experience gained during the use of the system enabled
the audit team to design, install, and test several modifications to the
calibrator to improve reliability in future use. The modifications and the
instructions for use of the modified 8861 are reported herein.
102
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B.2 MODIFICATIONS
All modifications to the 8861 are referenced to Figure B.I, the Modified
Bendix 8861P Flow Diagram and Figure B.2, the Modified Bendix 8861D Flow
Diagram. All modifications have been completed, tested, and documented.
B.2.1 ZERO AIR SYSTEM
As delivered, the Bendix 8861D dilution air system is supplied with a
small and generally inadequate zero air scrubber system. Only at relatively
low flow rates and low background pollutant levels was the supplied scrubber
found to be adequate. The stock scrubber was removed and replaced with
Drierite columns as shown in Figure B.2. Generally a single column con-
taining 6-16 mesh coconut shell activated charcoal was found to be adequate
for pollutant removal. Two columns charged with Drierite were used for
water vapor removal. Ascarite was employed only in cases where carbon
dioxide removal was required and this usage occurred only during the in-
vestigation of the effect of carbon dioxide on the response of flame
photometric sulfur dioxide analyzers.
The series configuration of Drierite and charcoal was adequate for all
audit work conducted with the exception of audits involving carbon monoxide
and/or hydrocarbon analyzers. Cylinder zero air was substituted in these
instances.
B.2.2 FLOW MEASURING SYSTEM
Flow control within the Bendix 8861 as delivered is by pressure drop
across capillaries. All five dilution air capillaries and the nitric oxide
capillary are housed in a thermostated chamber. Purge flow through the
permeation tube chamber is controlled by capillary but this capillary is
not temperature controlled.
During the course of work involving the 8861, it became obvious that
103
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CD CX
o:
ts
o
o
00
00
X
I—I
o
•z.
LLJ
CO
O
O
O
02
UJ
104
-------
105
-------
mass flow meters would be a desirable addition to the system. The 8861 is
only conveniently flow calibrated in a laboratory under controlled conditions
of temperature and pressure. Since the 8861 must be transported and used
under a variety of conditions involving significant departure from normal
temperature and pressure, the capability of measuring mass flow would repre-
sent an improvement. Additionally, the mass flow meters are an invaluable
aid in leak checking the 8861 after field transport and prior to use.
The first mass flow meter added to the system is shown in Figure B.2 as
MFM 1, a 0-5 liter per minute Tylan unit just upstream of pressure regulator
PR2. Total dilution air flow is conveniently monitored at this point. Addi-
tionally, the entire 8861D system is conveniently leak checked by sealing
the 8861 outlet port and monitoring the MFM 1 flow signal. The calibration
data and calibration curve for MFM 1, Dilution Air, are presented as Table
B.I and Figure B.3 respectively. The second mass flow meter is shown in
Figure B.2 as MFM 2, a 0-10 cc/minute Tylan unit just upstream of pressure
regulator PR1. This flow meter monitors nitric oxide flow from an external
cylinder. The calibration data and the calibration curve are presented as
Table B.2 and Figure B.4 respectively. The third mass flow meter is shown
in Figure B.2 as MFM 3, a 0-500 cc/minute Tylan unit just upstream of the
ozone generator serving to monitor the air flow over the ultraviolet lamp
within the generator. The calibration data and calibration curve are pre-
sented as Table B.3 and Figure B.5 respectively. The fourth mass flow meter
is shown in Figure B.I as MFM 4, a 0-100 cc/minute Tylan mass flow controller
just upstream of the permeation tube chamber. This mass flow controller
replaces the flow controlling capillary which, prior to removal, limited
flow through the permeation tube chamber to 5 cc/minute. The capillary
removed was not thermostated and variations in room temperature during
audits of sulfur analyzers caused the purge flow to change and eventually
result in an analyzer trace in oscillation reflecting the cyclic flow
pattern through the permeation tube chamber. The mass flow controller has
eliminated this problem and enables an operator selected purge flow rate up
to 100 cc/minute. The calibration data and calibration curve for MFM 4 is
presented as Table B.4 and Figure B.6 respectively.
106
-------
TABLE B.I MASS FLOW METER NO. 1 (Main Dilution Air)
MFM #1
VOLTS
0.500
1.000
1.500
2.000
2.500
3.000
3.500
4.000
4.500
5.000
5.500
6.000
P-2
% OF
GAUGE
47.
51.
18.
49.
88.
18.
32.
49.
68.
90.
41.
54.
5
0
5
0
0
0
5
0
5
0
0
5
TIME
FOR
1000CC
118.
58.
39.
30.
no.
100.
86.
75.
67.
60.
55.
50.
6 sec
0
2
0
2*
2*
6*
6*
4*
0*
0*
0*
OBSERVED
FLOW
CC/MINUTE
506
1034
1531
2000
2517
2994
3464
3968
4451
5000
5455
6000
FLOW
CC/MINUTE
AT ST'D
CONDITIONS
451
922
1364
1782
2243
2668
3087
3536
3966
4456
4861
5347
ORIFICE
1
1
1
1
1
1
1
1
1
1
1
1
+ 2
+ 2 +
+ 2 +
+ 2 +
+ 2 +
+ 2 +
+ 2 +
+ 2 +
+ 2 +
+ 2 +
+ 2 +
3
3
3
3
3
3
3
3
3
3
+ 4
+ 4
+ 4
+ 4
+ 4
+ 4 +
+ 4 +
5
5
*Time for 500 cc
All flows corrected to standard conditions of 0°C and 760 mm Hg.
Correction factor = Observed Flow x
= 0.891
P 273 1 [748 - 18.61
[273 + 2l| I 760 I
107
-------
1000
2000 3000 4000
FLOW, SCCM
5000
FIGURE B.3 MFM #1
108
-------
TABLE B.2 MASS FLOW METER NO. 2 (NO)
P-2
MFM #2 % OF
VOLTS GAUGE
0.445
0.618
0.800
1.000
1.220
1.446
1.670
1.920
2.175
2.452
All flows
Correction
10
20
30
46
50
60
70
80
90
100
corrected to
TIME
FOR
4.0 CC
217.0
158.2
124.9
101.8
83.8
69.0
60.3
53.0
47.2
41.4
standard
factor = Observed Fit
OBSERVED
FLOW
CC/MINUTE
1.106
1.517
1.922
2.358
2.864
3.478
3.980
4.528
5.085
5.797
FLOW
CC/MINUTE
AT ST'D
CONDITIONS
0.99
1.36
1.72
2.11
2.56
3.11
3.56
4.05
3.55
5.19
conditions of 0°C and 760 mm Hg.
jw x f 273
M X [273 + 23.8
759.2 - 22.1
760
i. j
= 0.892
109
-------
567
FLOW, SCCM
8
10 11
FIGURE B.4 MFM #2 (NO)
no
-------
TABLE B.3 MASS FLOW METER NO. 3 (Ozone)
MFM #3
VOLTS
3.151
3.598
3.975
4.341
4.705
5.020
5.317
5.616
5.889
over
range
P-2
% OF
GAUGE
10
20
30
40
50
60
70
80
90
100
TIME
FOR
1000 CC
172.4
150.8
136.8
125.4
115.8
108.8
101.8
96.8
91.4
87.4
OBSERVED
FLOW
CC/MINUTE
348
398
438
478
518
551
589
620
656
686
FLOW
CC/MINUTE
AT ST'D
CONDITIONS
310
355
390
426
462
491
525
553
585
611
All flows corrected to standard conditions of 0°C and 760 mm Hg.
Correction factor = Observed Flow x
= 0.891
273
273 + 21
748 - 18.65
760
in
-------
6 -
5 -
oo
5 4
3 -
300 350
I
400
»
450
I
500
I
550
600 650
FLOW cc/min.
FIGURE B.5 MFM #3 (Ozone)
112
-------
TABLE B.4 MASS FLOW METER NO. 4 (S02)
This is a mass flow controller operating from a 10 turn command potenti-
meter.
POTENTI-
METER
READING
100
200
300
400
500
600
700
800
900
1000
MFM #4
VOLTS
0.486
0.975
1.467
1.956
2.445
2.938
3.426
3.918
4.410
4.905
TIME
FOR
10 CC
53.9
26.6
17.8
13.3
10.6
89.8*
78.2*
68.2*
60.7*
54.6*
OBSERVED
FLOW
CC/MINUTE
11.131
22.556
33.708
45.113
56.604
66.815
76.726
87.976
98.847
109.890
FLOW
CC/MINUTE
AT ST'D
CONDITIONS
9.939
20.141
30.099
40.283
50.543
59.661
68.511
78.556
88.263
98.124
OVEN
TEMPERATURE
(VOLTS)
0.548**
0.548**
0.548**
0.548**
0.548**
0.548**
0.548**
0.548**
0.548**
0.548**
* Time for 100 cc
** 0.548 volts corresponds to 30.00°C
All flows corrected to standard conditions of 0°C and 760 mm Hg.
. Correction factor = Observed Flow x
= 0.893
273
273 + 22
753.1 - 19.8
760
113
-------
oo 3
h-
_i
o
--".t:
---I
7t:
;:.t;-
I- -:t-
777t7
-t:;-;
1.17;
:::-:^
NIFM».OQS\/
in::;:;
10
20
I
30
40 50 60
FLOW, SCCM
i
70
80
i
90
100
FIGURE B.6 MFM #4 (Sulfur)
114
-------
B.2.3 PERMEATION TUBE CHAMBER
A platinum resistance thermometer which measures the temperature of the
permeation tube is part of the Bendix design. It does not measure the air
temperature surrounding the permeation tube but rather the temperature of a
massive aluminum block surrounding the inner chamber.
A redundant back-up system capable of measuring purge air temperature
seemed highly desirable and was installed. A 3/4" diameter Teflon rod was
bored out, milled and threaded as shown in Figure B.7. The interior was
enlarged to accommodate two 5.0 cm permeation tubes. As a precaution
against future leaks, stainless steel bands were turned on the lathe and
press-fit over the ends of the Teflon permeation tube holder. As Teflon
ages it has a tendency to spread, which could cause leaks at both ends of
the holder. The steel bands will prevent this from occurring.
A male run "T" was fitted to the rear of the holder and a previously
calibrated glass thermistor was sealed into the side of the "T". The
thermistor was secured in place and the joint was made gas tight using
epoxy cement. Finally, a five foot length of 1/8" copper tubing was
spirally wound around the Teflon permeation tube holder and the three
components were assembled as shown in Figure B.8. The entire assembly is
contained within the permeation tube oven.
The outlet of the permeation tube holder was plugged, 15 psi air was
introduced and the system was leak-tested. The new design advantage be-
comes obvious at this point. If the rear connections are leak-free it is
unlikely they will leak in the future because this connection is never
disturbed. (In the old design, the permeation tube was inserted from the
rear.) To reconnect the permeation tube holder to the purge air it is only
necessary to make a final connection between the 'air in1 and the outlet of
mass flow controller No. 4. This connection is accessible for leak check-
ing.
To change permeation tubes the front fitting (purge air exit) can be
removed and the permeation tube becomes accessible with forceps. The
entire assembly is free to slide from the oven. Tilting the assembly
discharges the permeation tube from the Teflon cavity. After a new tube
115
-------
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KH
fi
CO
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tx.
3
116
-------
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Q-
UD
00
00
X
I—4
O
z
UJ
CO
Q
O
O
CO
GO
UJ
cc
117
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is inserted, all leak checks can be made external to the chamber.
With the new design, the purge air temperature may be monitored directly
just prior to exposure to the permeation tube. The leading copper tubing
insures that air temperature reaches the control temperature of 30.0°C re-
gardless of ambient temperature. The data included in Table B.4 clearly
shows that this temperature is maintained throughout the 0-100 SCCM oper-
ating range of MFC 4. The calibration curve for the Fenwal thermistor
installed in the tube holder is presented as Figure B.9.
B.2.4 MONITORING CONSOLE
The wiring diagram for the monitoring console enabling an operator to
display any mass flow meter signal or thermistor signal is shown in Figure
B.10. All pin assignments are given in Table B.5. The console consists of
a 6000 count digital voltmeter mounted in a control panel. The input to the
DVM is switched to display either the thermistor signal (position 1) or the
mass flowmeter signals (MFM 1-4, positions 2-5). The command potentiometer
for MFM 4 is also mounted on the panel. The pot is 10-turn and is linearly
proportional to a flow of 0-100 cc/minute through the permeation tube
chamber.
All of the mass flow meters require a regulated +_ 15 VDC supply for
operation. Connections to Tylan power supply PS-14 are shown in Figure
B.10. Detail for connections (typical, 4 places) to MFM 4 is also shown in
Figure B.10. The Fenwal thermistor mounted in the permeation tube chamber
is in a voltage divider across the regulated + 15 VDC Tylan supply.
118
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31.0-
o 30.0-
29.0-
LU
28.0.
30.O°C
I i t i i 1 I r
.51 .52 .53 .54 .55 .56 .57 .58
INDICATED VOLTS
FIGURE B.9 CALIBRATION OF FENWAL GB41P2 THERMISTOR
119
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TABLE B.5
Pin
Assignment
W
S
17
U
V
R
L
12
N
P
K
E
7
F
J
PIN ASSIGNMENTS - MASS
FLOW METER NUMBER 1
AIR
0-5LPM
Function
-15 V
Case Gnd.
Common
Output
+15V
FLOW METER NUMBER 2
NO
0-10 cc/min
-15V
Case Gnd.
Common
Output
+15V
FLOW METER NUMBER 3
OZONE
0-55 cc/min
-15V
Case Gnd.
Common
Output
+15V
FLOW METERS
Wire
Color Code
White
Braided shield
Black
Green
Red
White
Braided shield
Black
Green
Red
White
Braided shield
Black
Green
Red
120
(continued)
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TABLE B.5 (continued)
FLOW METER/CONTROLLER NUMBER 4
so2
0-100 cc/min
Pin
Assignment Function
25 -15V
Y Central
X Case Gnd.
a Common
Z Output
F +15V
Wire
Color Code
White
Yellow
Braided Shield
Black
Green
Red
121
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DETAIL-MFM. NO. 4
FC 26O
IOO ec/mio.
Switch
Position
1
2
3
4
5
CONTROL
veusw)
O-Sv/OC
COMK.
(1BLACK)
ounvr
COMM.
COMM.
AN
JER
PLY
14
1 v^
\O TUR
BOURN
POT.
Signal
Thermistoi
MFM 1 (Oil
MFM 2 (NO
MFM 3 (Oz<
MFM 4 (SO.
-D OUTPUT 1 VIOLET
- K otrrPUT 3 6REEN ,
-A -t-Bv/OC PINK — |
-5 COP<^^^ON BiACK — •
-(t> COMMON SLOE — i
-7 -MSvOC ORANGE -i
Y ' V
N
IS
1 3;
5
«
ution)
( H5VAC
3ne)
,)
-i r-IBvDC
r«o>)
ZENER
TESTPT
4
6
D
F
VALVE
TE5TP
-ISv/D
(WHITE,
^
'• ^_^\_ . •
, Ti-
1 j
i
RED
3
^ *TJ :
• -t
re' THE
Tft2 i
A «
uj
i
DVM
TR?i '
4
FENVVA\_
THERMISTOR
FIGURE B.10 WIRING DIAGRAM
(Interconnections between Power Supply - Mass Flow Meter
and Control Box mounted on the modified Bendix 8861P)
122
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B.3 INSTRUCTIONS FOR USE OF THE MODIFIED 8861
The following operating procedures pertain to the operation of the
modified Bendix 8861D and 8861P and involve the use of mass flow meters to
measure the flow of dilution air and/or calibration gas delivered by the
above.
To set up for audit proceed as follows:
1. Open both cases, side by side and make the following intercon-
nections;
a) Connect the 52" Teflon line between the "Clean Air" on the
8861D and the input filter marked "air in" in the 8861 P. This
line supplies purge air to the S0£ permeation assembly. Refer
to Figure B.I, Modified Bendix 8861P Flow Diagram and Figure B.2,
Modified Bendix 8861D Flow Diagram.
b) Turn the toggle switch VI, Figure B.I to "off" when the pump in
the 8861D is started.
c) Make sure the air scrubbers are connected together as shown in
Figure B.2 (i.e., drierite - drierite - carbon - ascarite).
Connect the first drierite bulb to the air "out" and the outlet
of the ascarite bulb to the "in" connections on the 8861D.
These scrubbers will produce dry pollutant free air, free of
carbon dioxide. Under certain conditions it may be advisable
to use charcoal alone depending on the analyzer being cali-
brated or audited.
d) Connect the mass flow meter cables being careful to match the
number on the plug with the number on the mass flow meter
(i.e., No. 1, 5.0 LPM dilution air; No. 2, 10 cc NO; No. 3,
500 cc ozone; No. 4 100 cc S02). Use the Phillips head screws
to secure the plug to the circuit board connection on the top
123
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of the mass flow meter.
e) Plug in the 8861D using the plug strip mounted in the 8861P
and connect the plug strip to a 115V source.
f) Turn on the power switch on the 8861D. This turns on the pump.
The toggle valve mentioned in part b) above can now be turned
to "off" and the "stand-by - off-on" switch on the 8861P can
now be turned to "on".
The equipment is now in operation.
2. Dilution flow calculations can be made as shown in the "Audit
Procedures for RAPS Instrument Systems" and reviewed briefly below:
For S02:
C = £R x £
where: C is concentration in PPM
PR is permeation rate in ng/min. (Ref. oven temperature)
K is 22.4/M.W. of permeation gas (M.W. S02 = 64)
F is permeation oven flow rate
F. is dilution flow rate
d
For NO:
r v = r v
Lri L2V2
where: C-, is concentration of NO source gas
V-, is the flow rate of NO source gas
C2 is final concentration
V2 is total dilution flow rate.
3. The quantity of dilution flow can be read from the graphs accom-
panying this report. The total dilution air flow is read from mass
flow meter No. 1, the NO flow is read from mass flow meter No. 2,
the ozone is read from mass flow meter No. 3 and the S02 is read
from mass flow meter No. 4. The volume of purge air entering the
permeation oven is continuously variable between 2-100 cc/min and
care must be taken to insure that this volume is added to F. when
d
124
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the flow calculations are made.
4. On shut-down, disassemble in the reverse order to set-up and observe
the following precautions:
a) Turn the "stand-by, off, on" switch to stand-by. The air pump
is now running off the internal battery in the 8861 P.
b) The toggle valve VI is turned to "on".
c) The "air-in" filter in the 8861D is closed with a cap. If this
is not done, air from the pump escapes through the filter and
no purge air goes through the permeation oven. As a final check,
turn the selector switch on the control panel to position 5 and
note that a voltage is indicated on mass flow meter No. 4 show-
ing that purge air is flowing through the permeation oven.
d) The Bendix 8861P should not be left on its stand-by battery for
more than 24 hours. High current drain will nearly totally
discharge the battery in this time interval.
125
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/4-79-031
3. RECIPIENT'S ACCESSION"NO.
4. TITLE ANDSUBTITLE
REGIONAL AIR POLLUTION STUDY
Quality Assurance Audits
5. REPORT DATE
May 1979
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
0. Klein and F. Littman
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Rockwell International
Air Monitoring Center
11640 Administration Drive
Creve Coeur, MO 63141
10. PROGRAM ELEMENT NO.
1AA603 AA-126 (FY-79)
11. CONTRACT/GRANT NO.
68-02-2093
Task Order 106
12. SPONSORING AGENCY NAME AND ADDRESS
Environmental Sciences Research Laboratory - RTP, NC
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
Final
14. SPONSORING AGENCY CODE
EPA/600/09
15. SUPPLEMENTARY NOTES
16. ABSTRACT
RAPS Quality Assurance audits were conducted under this Task Order In contin-
uation of the audit program, previously conducted under Task Order No. 58, Quantita-
tive field audits were conducted of the Regional Air Monitoring System (RAMS) Air
Monitoring Stations, Local Air Monitoring Stations (State of Illinois, St, Louis City
and St. Louis County), RAPS helicopters and various measurement systems employed in
the RAPS intensive studies, Audit results are reported for systems measuring NO, NO
03, S02, total sulfur, total hydrocarbons,
CH4 and CO,
An Investigation was conducted on the effect of Teflon parttculate filters on
NO, NOo, 0,, and SQ2 concentrations In sampled air, Measured sample losses are
reported for synthetic pollutant T- air mixtures sampled through new and used filters
under both dry and humid conditions. The investigation also reyealed effects of
humidity on the response of analyzers to the various pollutants.
The accuracy of S02 calibration mixtures prepared with the commercial dynamic
calibration system employed In the audits was investigated, AS a result of this
Investigation and experience gained during the audits, the calibration system was
modified to Improve performance under field conditions,
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
COS AT I Field/Group
* Air Pollution
* Quality Assurance
Auditing
St. Louis, MO
Regional Air
Pollution Study
13B
14D
05A
18. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19. SECURITY CLASS (ThisReport)
UNCLASSIFIED
21. NO. OF PAGES
134
20. SECURITY CLASS (Thispage)
UNCLASSIFIED
22. PRICE
EPA Form 2220-1 (9-73)
126
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