EPA-600/2-77-021
February 1977
Environmental Protection Technology Series
ALARM-LEVEL MONITOR FOR S02
EMISSIONS FROM STATIONARY
SOURCES
Environmental Sciences Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park, Nortfi Carolina 27711
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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 five series. These five broad
categories were established to facilitate further development and application of
environmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The five series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
This report has been assigned to the ENVIRONMENTAL PROTECTION
TECHNOLOGY series. This series describes research performed to develop and
demonstrate instrumentation, equipment, and methodology to repair or prevent
environmental degradation from point and non-point sources of pollution. This
work provides the new or improved technology required for the control and
treatment of pollution sources to meet environmental quality standards.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA Report No. 600/2-77-021
February 1977
ALARM-LEVEL MONITOR FOR S0_
EMISSIONS FROM STATIONARY SOURCES
by
Donald A. Wallace
and
Wayne Perkins
International Biophysics Corp,
2700 DuPont Drive
Irvine, California, 92664 .
Contract No. 68-02-2233
Project Officer
Roosevelt Rollins
Emissions Measurement and Characterization Division
Environmental Science Research Laboratory
Research Triangle Park, North Carolina 27711
ENVIRONMENTAL SCIENCES RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U. S. ENVIRONMENTAL PROTECTION AGENCY
RESEARCH TRIANGLE PARK, NORTH CAROLINA 27711
-------
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 recommendation for use.
-------
ABSTRACT
A field prototype, alarm-level monitor for SO- emissions
from stationary sources was designed, fabricated and tested.
The monitor was designed to be inexpensive, simple to operate
and easily maintained. The monitoring system is an extractive
type that employs an air aspirator to pull a sample through a
probe and sample conditioning assembly. The gas sample flows
through an analyzer that contains an electrochemical cell as
the sensing element. The analyzer has the sensitivity to
detect SO,, concentrations in a single range from 0 to 1000
parts per Million. Visual and audible alarms are activated
when SO- emissions are in excess of a preset level.
111
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CONTENTS
Abstract iii
Figures and Tables * v
1. Introduction 1
2. Summary 3
3. Conclusions 5
4. S0_ Monitor Description 7
5. SO- Sensor Operating Principle ' 12
6. Laboratory Tests 15
7. Field Tests 17
Appendix 24
A. Laboratory Reports of S02 Field Samples 25
IV.
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FIGURES AND TABLES
Page
Figures
Figure 1. S02 Monitory System 8
Figure 2. SOj Monitor Instrument Cabinet 9
Figure 3. Electrical Chemical S02 Gas Sensor 13
Figure 4. S02 Sensor Span Drift Test 16
Figure 5. S02 Monitor Field Test Setup 18
Figure 6a. Field Test Chart Records 21
Figure 6b. Field Test Chart Records 22
Figure 6c. Field Test Chart Records 23
Tables
Table 1. System Specifications 11
Table 2. Interference Equivalents 14
Table 3. Analyzer Accuracy Determination 20
v.
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SEGT-ION: .1 .
INTRODUCTION
EPA regulations require that all new and modified station-
ary sources be equipped and monitored for specific pollutants
emitted from specified categories of sources. The applicable
monitoring systems must be capable of quantitatively detecting
the pollutant gases of interest and generating and recording
emission data continuously as a function of time. There are
presently available several commercial monitoring systems to
meet these needs. Generally, these monitoring systems are com-
plex in design and require skilled personnel for set up, calibra-
tion, and operation. Thus, by nature, such monitoring systems
are expensive to purchase ($20,000-$50,000) as well as costly to
maintain. These costs are considered reasonable for new and
substantially modified sources.
However, existing sources outnumber new and modified sources
These existing unmodified sources are regulated by State Imple-
mentation Plans, which usually encompass legal limits on emis-
sions. Some states now require monitoring of emissions from
existing individual sources and it is anticipated that similar
requirements will be imposed for additional sources.
A large number of the existing source facilities are small
in size, production-wise, and do not normally employ the type of
skilled personnel needed to maintain complex monitoring systems.
It would be prohibitive, from a cost and practical standpoint,
to require monitoring these sources with present commercially
available systems.
Additionally, there are many existing sources in which the
type of operation involved does not necessitate the generation
of emission data on a continuous basis. Because of the nature
of the emissions (high concentrations for short periods and low
concentrations for longer period), continuous monitoring and
data collection is highly impractical. An alternate approach
would be to detect those instances when specified emission limits
are exceeded. An Alarm-type monitoring system will achieve es-
sentially the same control as the more complex systems but with
the inherent advantages of being simpler in deisgn and operation,
requiring a minimum of data collection and analysis, and thus
less costly to purchase and maintain.
-------
The purpose of this contract was to develop a field proto-
type, alarm-level monitor for sulfur-dioxide (802) emissions
from stationary sources. The system design was to be as simple
and straightforward as practical and such that future commercial
production of the system is possible.
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SECTION 2
SUMMARY
A field prototype alarm-level monitor for SC>2 emissions from
.stationary sources was designed, developed, fabricated and field
tested under this contract.
Design criteria for the monitor resulted from a parametric
study of all factors impacting a specific monitoring concept—
that concept being that small, unsophisticated, existing source
facilities faced with meeting local legal limits on emissions
need an inexpensive monitor that requires minimum instrument
maintenance. The parametric study considered the following:
a general industry emission study to identify potential
instrument users and obtain an overview of typical effluent
composition, effluent levels, and source monitoring operat-
ing practice.
- a study of applicable regulatory guidelines and stand-
ards for S02 source emissions to determine the required
instrument concentration level capability.
- general operator skill level, industrial procedures, ser-
vicing and maintenance requirements and reliability under
field service conditions.
- SC>2 measuring concepts, and potential manufacturing cost
reductions through design simplification.
Results of the study were as follows:
- An electrochemical transducer type SC>2 sensor most close-
ly matched the criteria.
- Analyzer sensitivity from 100-1000 ppm would meet the
vast majority of field applications.
- Visual and acoustical signaling devices activated when
preselected adjustable emission levels have been reached
is adequate operator alarm.
- Measurement accuracy of ± 20% relative to EPA method No.
6 is adequate for this usage.
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- System response time should be 10 minutes or less.
- Every effort should be made in the design to incorporate
plug-in component modules, roomy instrument cabinets, etc.,
for easy maintenance.
An electrochemical analyzer complete with refrigerated sample
dryer, heat trace sample line and sample probe was developed
and tested. The tests, performed on the scrubber section of a
light weight aggregate rotary kiln process, indicated the design
performance goals are met by the analyzer.
A cost analysis of the monitoring system indicated that
the system may be marketed at a cost below $2,500 excluding the
probe assembly.
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SECTION ,3
CONCLUSIONS
A source monitoring system was developed under this contract
for visual and audible alarm when SO? emission exceeds a prede-
termined level. The results of the field tests of this system
are presented below.
(1) The nature of the process plant chosen for field test
was such that the hot gas exhaust section had an exceeding-
ly high particulate loading which plugged the sample probe
almost immediately. Measurements were then taken on the
downstream side of a wet scrubber. The gas at this point
was cool and the particulate level was reduced but the sam-
ple was saturated with water vapor. This water vapor con-
densed in the unheated probe and backflushing was required
from time to time to prevent blockage.
In by far the majority of sources which use this instru-
ment, the gas will be much hotter, the probe temperature
will be higher and the water vapor condensation should not
be a problem. The sample line also may be backflushed if
the probe filter becomes loaded with particulates, using
the high pressure auxiliary air supply.
(2) The system calibration concept called for a pressure
operated check valve in the probe to allow span gas to be
introduced at the probe, thus providing a true 'system1
calibration. Unfortunately, in the field test the stack
gas was cool as well as the probe and check valve thus pre-
venting the check valve from seating and sealing properly
on a Teflon seat. The calibration concept seems correct,
however, further testing at hotter temperatures is needed.
(3) The new electrochemical cell developed for the analyzer
functioned well. Improved features such as the large elec-
trolyte reservoir for long operating life and the elimina-
tion of temperature conditioning on the cell cannot be
properly judged without long term testing which was not
possible in this program.
(4) Wherever the sample probe or stack fittings are exposed
to a gas flow with high water vapor, 316 stainless steel
should be used rather than 304 to reduce corrosion of the
metal.
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(5) The cyclic concentration component observed in some of
the analyzer data could not be traced to either a plant per-
formance parameter or to the analyzer. Further tests are
needed to fully establish analyzer performance.
(6) The field test, which compared the new analyzer con-
centration measurement on a strip chart to an EPA Method 6
measurement on side-byside sampling resulted in an analyzer
relative accuracy of 16.7%.
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SECTION 4
S02 MONITOR SYSTEM DESCRIPTION
The instrument system developed under this contract is an
extractive type that employs a probe assembly for taking a gas
sample from any selected location in a stack, flue or process
stream. Principle elements of the system are illustrated sche-
matically in Figure 1. A check valve located near the probe tip
provides a method of introducing span gas for true system cali-
bration by passing the calibration gas through every element of
the instrument system. A filter also located in the probe line
removes any solid particulates such as fly-ash from the sample.
The sample gas flows from the probe to the'instrument cabinet,
shown in Figure 2, through heat-traced line to prevent water
vapor condensation and consequent SO, loss by absorption in the
water. The sample passes through a heat exchanger coil which is
cooled by a reliable, low cost refrigeration unit. The gas
sample stream along with any water which is condensed out of the
gas stream at the end of the heat exchanger, enters a separator
section wherein a portion of the dried gas sample is continuous-
ly extracted for S0~ analysis.
The total probe gas sample is pulled through the system,
including the separator, by means of an air operated high volume
flow aspirator. The high volume sample flow results in a short
residence time for the SC»2 in the gas stream with the separa-
tor's condensed water. The low volume flow dry gas sample is
drawn from the separator by a separate vacuum pump, passes
through a flowrator and final particulate filter and enters the
S02 analyzer cell.
The analyzer contains an electrochemical membrane polar-
graphic type cartridge sensor. The sensor distinguishes the S02
gas from other components in the gas stream and produces an
electric current by electro-catalytic oxidation which is direct-
ly proportional to the S02 concentration. The concentration is
indicated on an analog meter and the signal is available as a
recorder output.
The analyzer is calibrated using 'zero1 gas as supplied by
atmospheric air which has been scrubbed of S02 and by means of
calibration span gas of known concentration introduced either at
the monitor cabinet or at the probe itself.
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00
'. CHECK VALVE
I . J._... ^
'. : PARTI CULATE
FILTER
• ~~^^ A
; VARIABLE
X STACK
rcF£L-X
1 1 ^N
| ° | BACK N~
| o FLUSH
L 1
TEMP
CONTROL
MODULE
AUX AIR
^CAL GAS
L>>
f1!
HEAT TRACE
SAMPLE LINE
VAC
GAGE TEMP
—• T ® ©
^ \7, T I ^HEAT EXCHANGER
i-rsfe^M.- i- ,~\ /
•*- SAMPLE r^/I
1 S3 | REFRIG.
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SEPARATOR -v _Z_. CSUOTI. _^ „_„_ -a(; SCRUBBER
^WF=7L SAMPLE ^.qc^ZERO GAS j 1 ^ aTM aTR
KTL-i i 1 — n /I 1 hst*k . -n^-CAL GAS
L— CXH 1— i / 1 rJ I^H u
ASPIRATOR 1 \^J
T PUMP
f~l DISCHARGE
ALARM H j , i 1
LIGHT T"~t- — {J 1 — • 1
1
ALARM /V/[S-L
HORN (UI/P- (J->
ALARM MO
. A
\ |
j S02 J
. ft SENSOR IS
| ^ CELL | FLOWMETER
DULE SO2 ANALYZER MODULE
FIGURE 1. S02 MONITOR SYSTEM.
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HEAT TRACED
SAMPLE LINE
ELEC CONTROL
PANEL PLUG-IN
MODULE
TEMP CONTROL
PLUG-IN MODULE
GAS
SELECTOR
MODULE
ALARM
LIGHT
S02 ANALYZER
PLUG-IN MODULE
ALARM
PLUG-IN MODULE
L ALARM '
'". ANNUNCIATOR
ANALYZER
PARTICULATE
FILTER
NEMA
ENCLOSURE
GAS/WATER
SEPARATOR
ASPIRATOR
REFRIGERATION
UNIT
ANALYZER
SAMPLE GAS
PUMP
HEAT EXCHANGER
FIGURE 2. SO2 MONITOR INSTRUMENT CABINET.
•
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An alarm module is adjustable to any desired SC>2 concen-
tration level. SC>2 levels above this preselected level are indi-
cated both by activation of ah annunciator and by an external
light.
The sample line may be backflushed if the probe filter be-
comes loaded with particulates, using the high pressure auxil-
iary air supply.
The monitoring system, with the exception of the probe and
sample line, is housed in a NEMA enclosure for rugged external
environment protection. The system is conveniently broken down
into [subsystems which, are designed as individual plug-in modules
to expedite removal by nontechnical personnel at the field site.
The subsytems include the following:
a) Analyzer Plug-in Module.
b) Temperature Control Plug-in Module.
c) Alarm Plug-in Module.
d) Electrical Control Panel Plug-in Module.
e) Gas Handling Panel.
f) Refrigeration/Heat Exchanger Unit.
Each of these subsystems can be easily removed for factory
maintenance. The selected NEMA enclosure is purposely large
and roomy to ease maintenance.
System's performance specifications are shown in Table 1.
10
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TABLE 1. SYSTEM SPECIFICATIONS
Range: 0-1000 ppm
Direct reading in parts per million by volume.
Span has 300% over range capability.
Accuracy: System- - 20% of f.s. max. accumulated error for
24 hours. +
Analyzer- -2% of f.s. referenced to span gas
Repeatability: -1% of f.s. •
Minimum Detectability: -1% of f.s.
Linearity: -1% of f.s.
Span Drift: ^1% of f.s. (4 hrs)
-2% of f.s. (24 hrs)
Electronic Drift: -1% of f.s. per 24 hrs.
Response Time: 30 sec max to 95% of f.s.
o
Ambient Operating Temp: 10-115 F
Power: 115 Vac, 60 Hz, 800 watt
11
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SECTION 5
S02 SENSOR OPERATING PRINCIPLE
The SO- sensor, located in the analyzer, belongs to the
category of electrochemical membrane-type polarographic gas
detectors. The gas sample flows across the sensor membrane
during gas stream passage between inlet and outlet parts.
Some of the gas molecules diffuse through the membrane and
dissolve in a thin liquid film at the sensing electrode
surface where they are absorbed and undergo electroxidation or
reduction. The opposite reaction occurs at a reference
electrode resulting in electron current flow in the load
circuit. A separating matrix insulates the sensing and
reference electrodes and serves as an ionic conductor to
maintain electro-neutrality. Spare electrolyte is contained
in a reservoir in a bound state and maintains contact with the
matrix through capillary action. The sensor unit is shown in
Figure 3.
Sensor Selectivity
Sensor selectivity is based on the standard electrode
potential of the electrochemical reaction involving the gas
being measured. By controlling the potentials at which the
electrode reactions occur, reactions of certain interfering
gases can be minimized, thereby removing them as
interferences. With the SO- sensor biased to maximize SO
response the interference equivalents for other possible gas
constituents is given in Table 2 as determined by tests
reported in Reference 1.
12
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DISCHARGE
GAS
SAMPLE
FLOW
FIGURES. ELECTRO CHEMICAL SO2 GAS SENSOR.
13
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TABLE 2. INTERFERENCE EQUIVALENTS
Interference Gas
H2S
°2
MO
NO,
CO
He
CO,
KU
Equivalent Ratio
26:1
-0.3:1
1000:1
100:1
-0.6:1
100:1
100:1
1000:1
1000:0
Reference-..
"Evaluation of Portable Sulfur Dioxide Meters."
Contract No. HSM-99-73-1 (T.O. No. 2) for National Institute
for Occupational Safety and Health, by Research Triangle
Institute, Research Triangle Park, North Carolina 27709.
14
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SECTION 6
LABORATORY TESTS
Long term zero drift and span drift tests were
performed to check sensor cell performance. A sixty-four
(64) hour unattended test was performed in the laboratory
using 444 ppm SO- span gas and a programmable timer set on a
10% duty cycle i.e., one minute of sample gas and nine
minutes of zero gas. Portions of the chart record are shown
in Figure 4. The zero drift for the 64 hour period is
observed to be essentially zero.
The span drifted from 444 ppm to approximately 495
ppm { 11.5%) in the first eight (8) hours of operation while
the sensor cell was reaching equilibrium. For the regaining
56 hours of test the span remained constant with -5 ppm
maximum variation.
15
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16
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SECTION 7
FIELD TESTS
Field tests of the SO- Alarm Monitor were performed
during the month of May 1976 at the Crestlite Corporation's
light weight aggregate plant in San Clemente, California. The
aggregate is produced continuously in a rotary kiln. Exhaust
from kiln contains both large and fine particulate as well as
sulfur compounds released from heated clay. The bulk of the
large particulate is removed by a series of cyclone separators
and a wet scrubber removes a significant portion of the fine
particulate from the gas stream.
The field tests were intended to demonstrate the
overall operational capability of the monitoring system in a
field application and specifically to determine the system S02
measuring accuracy. The accuracy determination was
accomplished by comparing the integrated real time S0_
concentration reading of the monitoring system to the sample
concentration obtained by the standard EPA method 6. This side
by side sampling was performed at the downstream end of the wet
-scrubber as shown in Figure 5.
Testing was first attempted at the hot (500 F gas
temperature) upstream end of the wet scrubber, however, the
high particulate load plugged the sampling probe almost
immediately. Testing was accomplished then on the downstream
*end of the scrubber where the gas stream particulate
concentration was significantly reduced. The gas termperature
was very low in the scrubber exhaust resulting in partial
condensation of the saturated water vapor. The sampling probe
was pointed downstream to prevent excessive entertainment of
water mist into the sample gas stream. The low gas
temperature, however, meant a low probe temperature with some
water vapor condensation prior to the heated sample line.
Frequent backflushing was required to prevent flow restriction
during the one hour test period. The Teflon seat in the probe
check valve requires an elevated temperature in order to seal
properly with back pressure. With the probe at the low
temperature of the exhaust stack gas, the system calibration
from probe on through to analyzer could not be performed
because of the check valve leakage. Calibration thus was
performed at the analyzer for these field tests.
17
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CRESTLINE ROTARY KILN AGGREGATE PLANT
*.- - - ...
END OP SCRUBBER MEASUREMENT STATION
-
SO, MONITOR
INSTRUMENT CABINET
ON VAN AT THE
MEASUREMENT STATION
FIGURE 5. SO2 MONITOR FIELD TEST SETUP.
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Test Procedure
The system was backflushed and the analyzer zeroed and
spaned with 430 ppm span gas prior to each run. A strip chart
record was made of the analyzer output at the same time the
sample was being taken with the sampling train. All sampling
with the standard sampling train was done in accordance with
EPA method 6 procedures. These samples were analyzed by an
independent laboratory, Analytical Research Laboratories Inc.
of Monrovia, California, and compared with the integrated strip
chart record.
Test Results
The summarized results of eight tests are given in
Table 3 and the pertinent data from the sampling train tests in
Appendix A. The strip chart records from the S02 analyzer are
presented in Figure 6.
The comparative, results indicate the S02 Alarm Monitor
is well within the -20% accuracy design goal (with the
exception of one test point) assuming the sampling train test
results are accurate.
The cause of the cyclic analyzer signal in Run 2 and
part of Run 3 could not be traced to the analyzer which
responded normally during span gas calibration nor to any
cyclic plant process phenomena. Likewise, backflushing failed
to eliminate the phenomena. Further field tests are needed to
achieve a high level of reliability in the instrument.
19
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TABLE 3. ANALYZER ACCURACY DETERMINATION
Reference Method Difference
Test. Samples Analyzer 1-Hr* Continuous
No. Date & Time SO 9 - ppm SO? Aver age -ppm Ref. — ppm
1
2
3
4
5
6
7
8
5/10/76 10:00
5/12/76 9:00
5/12/76 10:00
5/12/76 11:00
5/12/76 12:00
5/12/76 13:00
5/12/76 14:00
5/12/76 15:00
372
276
242
223
174
221
262
328
328
206
241
203
193
238
253
300
-44
-70
-1
-20
+15
+17
-9
-28
NJ
O
Mean Reference Method
Test Value = 262.25
Mean Differences = 26
95% Confidence Intervals = -11.11
26 + 17.77
Accuracy = 262.25 = 16.7%
*Analyzer average obtained by integrating strip chart records
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FIGURE 6a. FIELD TEST CHART RECORDS.
-------
NJ
FI CURE 6b. FIELD TEST CHART RECORDS.
-------
to
U)
FIGURE 6c. FIELD TEST CHART RECORDS.
-------
APPENDIX A
Laboratory reports of SO? field samples from Crestlite
Corporation, San Clemente, California, by EPA Method 6.
24
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ANALYTICAL RESEARCH LABORATORIES, INC. -
Log Numb if r
160 TAYLOR STREET, P.O. BOX 369, MONROVIA, CALIFORNIA 91016
,213. 357-3247
Mate rial/Sample Identity
IBC - Celesco/Scrubber samples 7 runs, 14 samples,
Date Received
5/17/76
P.O. or R.P. Number
nqi i s?. s
Requested By
Wayne Perkins
Work Order
5141-01
Sample Disposition
D Retain Q Return 0 Destroy
Nature of Hazard
Due Date
5/24/76
Ship To:
Invoice to:
Wayne Perkins
2700 DuPont Drive
Irvine, CA 92715
International Biophysics
(same address)
Attn: Mr. Mike Turner
Nature of Work and Information Desired
SO,, SO? content, ppm
Sumrr-ary of Laboratory Report
Q. C. Level
SO,
son
Test #2
Test #3
Test #4
Test #5
Test #6
Test #7
Test #8
4. 7
33.
9. 5
8. 6
49.
20.
44.
276.
242.
223.
174.
221.
262.
328.
Ai o n-ytuts! p'c'.'di:1 fo t!:tnli, liiii r.-;>j'* »'. t"l>ai:t-tl fo' t'i; ;»c!-.»u/-lir.;l:»= of th- qj^'i/t .3!
OU'^O ••Tll.'.l ii proKib''"
-------
ANALYTICAL RESEARCH LABORATORIES, INC.
Log Number
160 TAYLOR STREET. P.O. BOX 369. MONROVIA. CALIFORNIA 91016
(213)
357-3247 56039
Material/Sample Identity
IBC Celesco, Inc. /Method 8 Impingers
Date Received
5/13/76
P. O. or R. P. Number
Verbal
Requested By
Mr. Wayne E. Perkins
Work Order
f 131-01
Sample Disposition
D Retain G Return O Destroy
Nature of Hazard
Due Date
5/13/76
Ship T D:
IBC/Celesco, Inc.
2700 DuPont Drive
Irvine, Ca. 92664
Nature of Work and Information Desired
Sulfuric Acid and SO-
SumrniLry of Laboratory Report
Q. C. Level I 3
Blanks were nil for the peroxide and isopropanol solutions.
Ircpinger #1
139 mg, as H2SO4
113 mg, as SO,
Total H2SO4 received
Irrpinger #2
Total SO. received
41 ppm H2SO or SO,
821 mg, or 0. 01015 ft @ STP, or
372 ppm based on 29. 48 ft3 gas at 22°C
A'n
p.r
dy
•fi. Uie
» prior
: L
of Ihls r-V'0'1, v.S
wrill?n O"l>3'i:.o
RF
Da tc
5/1
,l« Of in par?, o-
3/76
Of Gf>y l"u!l Of in',iy,i:n c1;-" t".'CVfl fli-r':*-!!^, i'l t.'y O-lvrfi. ii:.j P' put
/^»
Approvcrl r''/x^^^^^» ^-
o wSoin il i
I-iSl/ n;oM'.T
r.ook- r
';i^e
a
Research and Development
26
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TECHNICAL REPORT DATA
I Please read Instructions on the reverse before completing}
1. REPORT NO.
EPA-600/2-77-021
3. RECIPIENT'S ACCEESIOP*NO.
4. TITLE ANDSUBTITLE
ALARM-LEVEL MONITOR FOR S09 EMISSIONS FROM
STATIONARY SOURCES ^
5. REPORT DATE
February 1977
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Donald A. Wallace and Wayne Perkins
8. PERFORMING ORGANIZATION REPORT NO
9. PERFORMING ORGANIZATION NAME AND ADDRESS
International Biophysics Corporation
2700 DuPont Drive
Irvine, California 92664
10. PROGRAM ELEMENT NO.
1AD712
11. CONTRACT/GRANT NO.
68-02-2233
12. SPONSORING AGENCY NAME AND ADDRESS
Environmental Sciences Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park, North Carolina 27711
13. TYPE OF REPORT AND PERIOD COVERED
Final 7/75-5/76
14. SPONSORING AGENCY CODE
EPA-ORD
15. SUPPLEMENTARY NOTES
16. ABSTRACT
A field prototype, alarm-level monitor for S0£ emissions from stationary
sources was designed, fabricated and tested. The monitor was designed to be
inexpensive, simple to operate and easily maintained. The monitoring system is
an extractive type that employs an air aspirator to pull a sample through a
probe and sample conditioning assembly. The gas sample flows through an analyzer
that contains an electrochemical cell as the sensing element. The analyzer has
the sensitivity to detect S02 concentrations in a single range from 0 to 1000
parts per million. Visual and audible alarms are activated when S02 emissions
are in excess of a preset level.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
*Air pollution
*Sulfur dioxide
Monitors
Electrochemical cells
*Warning systems
l).IDENTIFIERS/OPEN ENDED TERMS
c. COSATI 1'icld/Cjroup
13B
07B
07D
13L
18. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
I 19. SECURITY CLASS /Tills Kepnrtl
' UNCLASSIFIED
21. NO. OF PAGES
36
20. SECURITY CLASS f Tills page)
UNCLASSIFIED
22. PRICE
EPA Form 2220-1 (9-73)
27
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