United States
Environmental Protection
Agency
Environmental Monitoring
Systems Laboratory
Research Triangle Park NC 27711
Research and Development
EPA 600/S4-84-015 March 1984
Project  Summary
Performance  Test  Results and
Comparative  Data  for  Designated
Equivalent  Methods  for  Sulfur
Dioxide

R.M. Michie, Jr., F.F. McElroy, F.W. Sexton, and V.L Thompson
  This report summarizes the results of
postdesignation testing (both labora-
tory and field) conducted on 13 commer-
cially available ambient sulfur dioxide
(SO2)  analyzers to characterize their
performance, reliability, and operational
peculiarities.
  This Project Summary was developed
by EPA's Environmental Monitoring
Systems Laboratory. Research Triangle
Park. NC. to announce key findings of
the research project that is fully docu-
mented in a separate report of the same
title  (see Project Report ordering
information at back).

Introduction
  Under Part 53 of Title 40 of the Code of
Federal Regulations (40 CFR Part 53), the
U.S. Environmental Protection  Agency
(EPA) designates specific procedures or
analyzers  as reference or equivalent
methods for the monitoring of ambient air
pollutants. The methods are then accep-
table for use in National Air Monitoring
Stations (NAMS), State and Local  Air
Monitoring Stations (SLAMS), and Pre-
vention of Significant Deterioration (PSD)
monitoring. The Methods Standardiza-
tion Branch (MSB) of the Environmental
Monitoring Systems Laboratory (EMSL)
at Research Triangle Park, NC, is respon-
sible for EPA's reference and equivalent
method designation  program. In this
capacity, MSB has acquired performance
data and  other  information on these
methods, most of which arecommercially
available analyzer models.
  To summarize these data and make
them  available  to those who may find
them  beneficial in the selection of
analyzers, MSB, with the assistance of
the Research Triangle Institute (RTI),
prepared this report on designated
methods for sulfur dioxide.

Types of Tests Conducted
  Two principal types of postdesignation
tests were conducted by MSB. Phase I
tests were laboratory tests similar to the
predesignation tests required by 40 CFR
Part 53. Phase II tests simulated actual
use conditions and compared  simul-
taneously operating analyzers. Results
from these postdesignation tests provide
most of the data in this report.

Analyzers Tested
  The  report is intended to  cover all
currently designated reference methods
for S02. However, as of this writing, the
tests have not been completed for all
analyzers. Table 1 lists the designated
SO2 analyzers, their detection principles,
the tests that have been carried out, and
the dates of the tests.

Phase I Test Description and
Results
  Phase I laboratory performance tests
were conducted in accordance with the
same procedures and specifications
required for the applicant's predesigna-
tion tests, with the exception that fewer
trials (usually four) were performed for
each test parameter. All calibrations,
apparatus, pollutant standards, test
procedures, test atmospheres, and test
documentation were as specified in 40
CFR Part 53. (Individual reports contain-

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Table 1.    Sulfur Dioxide Analyzers Tested and Test Dates
Manufacturer
ASARCO
Beckman
Bendix
Lear Siegler
Lear Siegler
Meloy
Meloy
Meloy
Monitor Labs
Monitor Labs
Philips
Philips
Thermo Electron
Model
500
953
8303
SMWOO
AM2020
SA185-2A
SA285E
SA700
8450
8850
PW9700
PW9755
43
Detection
principle
COND
FD
FPD
D2
D2
FPD
FPD
FD
FPD
FD
EC
EC
FD
Phase 1 tests
May 1978-Jan 1979
May 1982-Apr 1983
NT
Sep 1976-May 1977
NT
Oct 1976-Feb 1977
NT
May 1982-Mar 1983
Mar 1977-Aug 1983
Aug 1982-June 1983
May 1978-Jan 1979
May 1978-Jan 1979
Oct 1976-Jan 1978
Phase II tests
NA
Nov 1978-Jun 1979
Feb 1979-Jun 1979
Nov 1978-Jun 1979
NT
Nov 1978-Jun 1979
Nov 1978-June 1979
NT
Nov 1978-Jun 1979
NT
NA
Jan 1979-Jun 1979
Nov 1978-Jun 1979
COND = Conduct/metric detection.
   FD - Fluorescence detection.
  FPD = Flame photometric detection.
   D2 - Second derivative spectroscopic detection.
   EC = Electrochemical (coulometric) detection.
   NA = No testing anticipated.
   NT = Not yet tested.
ing more detailed  information on the
Phase I  tests for  each  analyzer are
available from MSB.)
  Analyzers undergoing Phase I tests were
allowed to operate for several weeks prior
to actual testing. During this startup
period, preliminary  calibration and lin-
earity checks were performed. If a failure
occurred  during testing, the manufacturer
was notified and given the opportunity to
correct the failure. At the conclusion of
the tests, all failures and manufacturers'
involvement were included in routine
documentation.
  Phase  I tests included characterization
of output  signal noise  level, lower
detectable  limit (LDL),  interference
equivalents, 12-h and 24-h zero drifts,
span  drift at 20 and  80  percent of full
scale, lag time, rise time, fall time, and
precision. Results are reported in Table 2.
The total  interferent equivalent, zero drift,
and span drift data reported are averages
of absolute values;  all other values
represent the  arithmetic  averages of
several repetitions.
  Phase I results indicate that the 10S02
analyzers tested to date meet or exceed
the performance specifications. Testing
of three analyzers is not complete at this
time.

Phase II Test Description and
Results
  The Phase II test was intended to test
the analyzers in a more or less typical
ambient monitoring  configuration where
each  analyzer's stability, reliability,
general  performance, and operational
peculiarities  could be observed  and
compared with those of other analyzers.
The test was conducted on a group of
eight S02 analyzers operating simultane-
ously  over a period of 8  months. All
analyzers measured ambient air sampled
from a common manifold.
  All  test  analyzers were  installed,
calibrated, operated, and maintained in
strict accordance with the manufacturer's
instruction manual and good monitoring
practice. Analyzers received a multipoint
calibration initially and once per month
during the test  period.  Zero and  span
checks were made two or three times per
week. Zero adjustments were made only if
the zero response  was not within 3
percent of  full-scale response  from
nominal; span adjustments were made
only if the span (slope of the calibration
curve) changed by more than 7 percent
from nominal. Data were acquired using
a  Monitor Labs 9300 Datalogger data
acquisition  system. The acquired data
were  transferred via magnetic tape to a
Hewlett-Packard 9845 Desk Top Compu-
ter where they were reduced to a useful
form.
  Phase II results indicate that most of
the S02 analyzers are stable and reliable.
The comparative data presented in Table
3  generally indicate high correlation
coefficients between 0.99 and  1.00.
Mean differences are generally with 4.0
ppb and standard deviations  of the
differences are generally less than 8.0
ppb. Likewise,  the individual analyzer
drift results  presented in Table 4 show
standard deviations of zero drifts to be
generally less than 5.0 ppb and standard
deviations of span drifts to be generally
less than 3.0 percent.

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Table 2. Phase 1 Postdesignation Test Results-Designated Sulfur Dioxide Analyzers
EPA Lear Lear
Performance specified- ASARCO Beckman Bendix Siegler Siegler Meloy Meloy Me/oy
parameters tions 500 953 8303 SM1000 AM2020 SA185-2A SA285E SA700
Noise-0% URL
Noise~8O% URL
Lower detectable limit
Interferents
CO
CO2
CiHt
HCI
H20
H2S
Metaxylene
Naphthalene
NH3
NO
NOi
03
Total
Zero drift-12 h
Zero drift-24 h
Span dr/ft-20% URL
Span dr/ft-80% URL
Lag time
Rise time
Fall time
Precision-20% URL
Precision-80% URL
0.005 ppm
0.005 ppm


0.02 ppm
0.02
0.02 ppm
0.02
0.02 ppm
0.02 ppm
0.02 ppm
0.02
0.02 ppm
0.02 ppm
O.02 ppm
0.02 ppm
 20 ppb
Maximum absolute difference.
ppb
Number of differences
Table 4. Phase II Postdesignation


Statistics
Standard deviation of
zero drift, ppb
Standard deviation of
span drift, %

Beckman
953
0.997
12.00

6.12

689

30
3,038
Test Results

Beckman
953

4.6

2.2

Bendix
8303
0.997
-2.61

4.68

1

21
1.969
for Drift

Bendix
8303

4.7

2.5
Lear
Siegler
SMI 000
0.936
+3.74

20.73

390

100
1.797

Lear
Siegler
SMI 000

16.1

5.5

Meloy
SA 185-2A
0.999
-3.81

3.95

0

20
3,285


Meloy
SA 185-2A

1.6

3.0

Meloy
SA285E
0.999
+0.50

3.43

0

17
3,290


Meloy
SA285E

2.4

2.3
Monitor
Labs
8450
0.999
+0.02

4.77

0

19
3.170

Monitor
Labs
8450

2.0

2.2

Philips
PW9755
0.998
+5.68

4.68

15

25
3.055


Philips
PW9755

3.4

2.5
Thermo
Electron
43
0.997
-0.43

7.20

49

30
3.209

Thermo
Electron
43

4.9

3.9.

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      Raymond M. Michie, Jr.. and Frederick W. Sexton are with the Research Triangle
        Institute, Research Triangle Park, NC 27709; the EPA authors Frank F. McElroy
        and Vinson L. Thompson (also the EPA Project Officers, see below) are with the
        Environmental Monitoring Systems Laboratory, Research Triangle Park, NC
        27711.
      The complete report, entitled "Performance Test Results and Comparative Data
        for Designated Equivalent Methods for Sulfur Dioxide," (Order No. PB 84-155
        373; Cost: $14.50, subject to change) will be available only from:
              National Technical Information Service
              5285 Port Royal Road
              Springfield, VA 22161
              Telephone: 703-487-4650
      The EPA Project Officers can be contacted at:
              Environmental Monitoring Systems Laboratory
              U.S. Environmental Protection Agency
              Research Triangle Park. NC 27711
      U.S. GOVERNMENT PRINTING OFFICE; 1984  759-015/7633
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Official Business
Penalty for Private Use $300

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