United States
Environmental Protection
Agency
Environmental Monitoring Systems
Laboratory
Research Triangle Park NC 27711
Research and Development
EPA-600/S4-83-026 Sept. 1983
4>EPA Project Summary
A Summary of the 1981 EPA
National Performance Audit
Program on Source
Measurements
E. W. Streib, R. G. Fuerst, and M. R. Midgett
In the spring and fall of 1981, the
Quality Assurance Division (QAD) con-
ducted its semi-annual National Audits
for certain Stationary Source Test
Methods. The audit materials consisted
of: a critical orifice for Method 5 (dry
gas meter only), five simulated, liquid
samples each for Method 6 (SO2) and
Method 7 (NOX), and two coal samples
for Method 19. Industrial laboratories,
contractors, universities, foreign la-
boratories, and local, state and Federal
agencies participated.
For the Method 5 spring audit, the
mean for all participants differed by
13.6% from the true (EPA) value. For
the fall audit, participants' mean was
4.3% from the true value. In the two
Method 6 audits, the median values
measured for 9 of 10 samples differed
by less than 1% from the true value,
whereas the median values for all 10
samples used in the two Method 7
audits were within 2% of the true
value. This was the first coal audit
conducted by QAD. For the sulfur, ash,
and moisture analysis, the participants'
accuracy was consistently better for
the higher concentration samples than
for the lower concentration samples.
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 doc-
umented in a separate report of the
same title (see Project Report ordering
information at back).
Introduction
In 1977 the Environmental Monitoring
Systems Laboratory (EMSL) of EPA estab-
lished a performance audit program to
evaluate the performance of organizations
that conduct source testing using EPA
Reference Methods. By participating in
this free and voluntary program, users of
these methods can compare their per-
formance to other laboratories conducting
similar measurements.
Laboratories participating in the audits
sent their data to the Source Branch and
later received a written report comparing
their results to EPA's. The participants had
eight weeks to return data to EPA. At the
end of this period, all data were statistically
analyzed to determine the participants'
precision and accuracy.
Audit Materials
In the Method 5 audit procedure, partici-
pants use a critical orifice to check the
calibration of the dry gas meter in their
EPA. Method 5 meter box. This device
allows a participant to compare his mea-
sured volume to EPA's expected volume.
Asummaryofthe 1 981 Methods audit
shows that 76% of the 350 laboratories
that requested samples returned data for
the spring and fall audits. The Code of
Federal Regulations requires that the dry
gas meter be calibrated to an accuracy of
within 2 percent, so this was used as the
criterion for accuracy. Only 42% of the
reporting laboratories in the 0381 audit
and 44% in the 0981 audit obtained this
accuracy.
For the Method 6 audit, a sample set of
five different dilutions of sulfuric acid was
prepared. This audit checks the partici-
pant's ability to analyze a Method 6 sample
for S02.
Asummaryofthe 1 981 Method6 audit
shows that 70% of the 31 1 laboratories
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requesting samples returned data for the
spring and fall audits. Two percent was
chosen as the criterion for accuracy. Of all
the data returned an average of 55% of the
participants achieved an accuracy within
2%.
For the Method 7 audit, a sample set of
five concentrations of potassium nitrate
was prepared. This audit checks the
participant's ability to analyze a Method 7
sample for NOX.
Asummaryofthe 1981 Method 7 audit
shows that 66% of the 250 laboratories
requesting samples returned data for the
spring and fall audits. Three percent was
chosen as the criterion for accuracy. Of all
the data returned, an average of 35% of
the participants achieved an accuracy of
3% for both audits.
The first coal audit by the Quality Assur-
ance Division was conducted in 1981.
This audit made use of two 60-mesh coal
samples. Participants analyzed each coal
sample for BTU content and percent sulfur,
moisture, and ash.
A summary of the 1981 coal audit
results shows that 83% of the 77 labora-
tories that requested samples returned
data. Five percent was chosen as'the
accuracy criterion for each of the four
parameters. For the high concentration of
sulfur and moisture, 61% and 80%, re-
spectively, of the analyses were within 5%
of the expected value. However for the low
concentration of sulfur and moisture, only
1 6% of the analyses were within the 5%
criterion. The data for the gross calorific
analysis were better, with 92% of the low
values and 85% of the high values within
5% of the expected value.
Recommendations
The Quality Assurance Division of the
Environmental Monitoring Systems La-
boratory maintains a repository of audit
samples for EPA Methods 6 and 7, and for
coal. These stable samples are available to
any laboratory having a need for them,
such as for training new personnel and
conducting quality control checks of the
laboratory. Since the expected values for
these samples are included with the
analysis instructions there is no require-
ment for the data to be returned to EPA
We recommend that participants make
use of this sample repository, to help
increase their overall analytical skills.
The EPA authors £. W. Streib (also the EPA contact, see below), R. G. Fuerst, and
M. R. Midgett are with the Environmental Monitoring Systems Laboratory,
Research Triangle Park, NC 27711.
The complete report, entitled "A Summary of the 1981 EPA National
Performance Audit Program on Source Measurements," (Order No. PB 83-
252 502; Cost: $10.00. subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA22161
Telephone: 703-487-4650
E. W. Streib can be contacted at:
Environmental Monitoring Systems Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
&U.S. GOVERNMENT PRINTING OFFICE: 1983-659-017/7177
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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