Formaldehyde Emission Measurement Method Comparison:

EPA Method 323 “Acetyl Acetone Derivitization Method”

And

EPA Reference Method 320 “Extractive Fourier Transform Infrared

(FTIR) Spectroscopy”

Technical Report

Prepared for:

Interstate Natural Gas Association of America American Petroleum Institute

10 G Street NE, Suite 700 1220 L Street, NW

Washington, DC 20002 Washington, DC 20005

Prepared by:

Innovative Environmental Solutions, Inc.

P.O. Box 177

Cary, IL 60013

May 12, 2010
Technical Report: Formaldehyde Methods Comparison

May 12, 2010

i

TABLE OF CONTENTS

Executive Summary.........................................................................................................................1

1. Introduction ...............................................................................................................................2

2. Approach ...................................................................................................................................3

2.1. Test Methods Measurements Uncertainty Overview .........................................................4

3. Test Results and Analysis..........................................................................................................6

4. Observations and Considerations for Methods Improvement .................................................11

5. Summary and Conclusions......................................................................................................13

Attachments

A. Technical Memorandum “EPA Method 323 Emission Test Data and Methodology Errors

from EPA Region 8..................................................................................................................13

B. Pertinent Correspondence and Test Reports ...........................................................................26

List of Tables

Table E-1. Summary of Method 323 and Method 320 Side-by-Side CH2O Measurements..........1

Table 1. Testing Summary ..............................................................................................................3

Table 2. Summary of Method 323 and Method 320 Formaldehyde Measurements .....................8

Table 3. Analysis of Method 323 and Method 320 CH2O Measurement Differences ..................9

Table 4. Analysis of Method 323 and Method 320 CH2O Measurement Differences with M320

Data Adjusted for QA Spike Recovery .........................................................................................10
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Executive Summary

This report provides the results of side-by-side formaldehyde (CH2O) measurements by

Proposed EPA Method 323 and EPA Method 320 (extractive FTIR). Table E-1 summarizes the

results from five test series conducted on both rich-burn and lean-burn gas-fired reciprocating

engines. The data in columns 2, 3, and 4 compare the average formaldehyde measurements for

each test series by the two methods. The Method 323 measurements were higher than the

Method 320 measurements for all of the test series with the difference ranging from 12 to 47

percent. The Method 320 QA spike recoveries can provide an indication of the measurement

bias. For this test program, all QA spike recoveries were less than 100% suggesting a low bias to

the measurements. The fifth column in Table E-1 shows the Method 320 measurements adjusted

for the QA spike recoveries. The data in the last column show good agreement, well within the

method uncertainties, between the Method 323 measurements and the QA spike adjusted Method

320 measurements. These data suggest that a low bias in the Method 320 measurements,

indicated by the low spike recoveries, contributed to the difference between the Method 323 and

Method 320 measurements for this test program.

Table E-1. Summary of Method 323 and Method 320 Side-by-Side CH2O Measurements.

M323 CH2O M320 CH2O

M323/

M320

M320SR CH2O (Corrected for

QA Spike Recovery)

A

M323/

M320SR

Test

Series

Avg ppmvd Avg ppmvd % Avg ppmvd %

1 31.3 26.3 119% 29.5 106%

2 48.5 32.9 147% 44.8 108%

3 52.0 44.1 118% 52.8 98%

4 58.4 50.5 116% 60.6 96%

5 47.3 42.3 112% 47.8 99%

A. M320 CH2O measurements adjusted by dividing by QA Spike Recovery.

In summary, based on accepted statistical evaluations to validate method performance, the results

demonstrate acceptable performance for Method 323 and support the conclusion that Method

323 should be included in the RICE NESHAP (40 CFR 63, Subpart ZZZZ) as an approved test

method for formaldehyde measurement. In addition, anomalous Method 323 results reported by

EPA in the March 2009 proposed RICE NESHAP amendments have been investigated and

determined to be a result of testing errors (i.e., human error). Therefore, Method 323 should be

accepted for formaldehyde measurement from gas-fired reciprocating engines and promulgated

as an accepted EPA test method when the final rule that amends 40 CFR 63 Subpart ZZZZ is

published, which is planned for late summer or fall 2010.
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1.0 Introduction

This report is for a project to compare formaldehyde emission measurements from gas-fired

reciprocating internal combustion engines using two test methods:

• Proposed EPA Method 323 “Measurement of Formaldehyde Emissions from Natural GasFired Stationary Sources—Acetyl Acetone Derivitization Method;” and

• EPA Method 320 “Measurement of Vapor Phase Organic and Inorganic Emissions by

Extractive Fourier Transform Infrared (FTIR) Spectroscopy.”

EPA Method 320 is a promulgated test method. An EPA Method 301 validation study was

successfully completed for EPA 323; however, the method has not been promulgated and thus

remains a proposed method.

This test program was initiated based on a request from the EPA Emission Measurement Center

(EMC) for additional side-by-side formaldehyde measurements using these two methods. This

request resulted from questionable test results from recent formaldehyde emission tests on gasfired (IC) internal combustion engines in EPA Region 8. These emission measurements were

performed using EPA 323 and the results were significantly lower (i.e. factor of 5 – 10) than

historical test results for these engines. These anomalous test results raised questions regarding

the reliability of EPA Method 323, and, as a result, Method 323 was excluded from the proposed

revisions to the National Emission Standards for Hazardous Air Pollutants (NESHAP) for

reciprocating internal combustion engines (RICE) (40 CFR 63 Subpart ZZZZ) as an option for

formaldehyde emission measurements.

EPA 320, and another FTIR test method, ASTM D 6348-03 “Standard Test Method for

Determination of Gaseous Compounds by Extractive Direct Interface Fourier Transform Infrared

(FTIR) Spectroscopy,” are the only formaldehyde test methods in the proposed RICE NESHAP

revisions. Subsequent review and analysis of the anomalous Method 323 test reports determined

numerous test method deviations, irregularities, and errors indicating the atypical measurements

were likely caused by testing errors rather than a fundamental test method deficiency. The test

reports review is documented in Attachment A, from an October 22, 2009 Technical

Memorandum “EPA Method 323 Emission Test Data and Methodology Errors from EPA Region

8” prepared for industry and EPA. EPA EMC further investigated the anomalous test results

and discovered additional testing errors. Consequently, EMC requested the side-by-side tests

documented in this report to further evaluate EPA Method 323 relative to the promulgated test

Method 320.

Section 2 of this report provides an overview of the project approach and considerations for the

side-by-side testing. The test methods uncertainties are discussed to provide context for the

methods comparison. Section 3 then presents and compares the formaldehyde measurements by

EPA 323 and EPA 320. Possible reasons for differences between the measurements by the two

test methods are discussed and evaluated. Observations during the testing and recommendations

for modifying and improving the test methods are then presented in Section 4 and Section 5

provides a summary and conclusions. The report attachments include related correspondence

and the full emission testing reports.
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2.0 Approach

EPA EMC requested side-by-side formaldehyde emission measurements by EPA Method 320

(M320) and EPA Method 323 (M323) on at least two uncontrolled gas-fired reciprocating IC

engines including at least one lean burn engine and one rich burn engine. Industry participation

resulted in five test series with testing completed on four engines, one rich burn engine and three

lean burn engines. These tests were conducted in Mississippi (MS), Oklahoma (OK), and

Wyoming (WY).

As shown in Table 1, at least three separate test-runs were conducted on each engine and for the

rich burn engine, two sets of three test-run tests were conducted at different operating conditions.

Thus, three sets of tests (i.e. three Test Series) were completed on lean burn engines and two sets

of tests were completed on rich burn engines for a total of 16 side-by-side tests.

Table 1. Testing Summary.

Test

Series

Site Unit

Test

Condition

Average O2

(% dry)

A

M323 Test

Runs

M320 Test

Runs

1 MS CB LSV-16-1 14.8 4 4

2 MS CB LSV-16-2 10.0 3 3

3 OK 80 hp 4SRB

High Load/

Low O2

1.3 3 3

4 OK 80 hp 4SRB

Mid Load/

High O2

2.3 3 3

5 WY Waukesha F18GL 8.0 3 3

A. EPA Method 3A measurements.

The emission measurements were conducted in accordance with the test methods. The test

reports in the attachments document the testing procedures. Other considerations for the side-byside tests included:

• Engines that normally operate at steady conditions (e.g. load, excess air) were selected for

testing to promote relatively stable formaldehyde emissions for the duration of the test

periods. Performance and evaluation of the Method 320 QA spike procedure, discussed in

Section 2.1, require a steady formaldehyde emission source;

• Sample ports were located well downstream of the engine exhaust manifolds such that the

engine exhaust gas would be well mixed/not stratified at the sampling location;

• The Method 320 and Method 323 sample probe inlets were located as close as practically

possible in the engine exhaust ducts;

• Method 323 sampling and Method 320 measurements were coordinated to start and stop at

the same time. The only exception to this schedule was that one of the Method 323 duplicate

sampling trains (for Test Series 5) was started approximately 15 minutes after the first train

due to a failed initial leak check; and

• To convert the wet FTIR formaldehyde measurements to a dry basis, engine exhaust moisture

measurements were conducted using the FTIR for the OK and WY tests. The moisture

measurements were compared to theoretical values calculated using combustion equations
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from fuel analyses and oxygen measurements as a QA check. For the MS tests, the moisture

was not directly measured and was determined using combustion equations from the fuel

analyses, oxygen measurements, and relative humidity. This is analogous to an “F-factor”

approach for determining exhaust emission rates.

2.1 Test Methods Measurement Uncertainty Overview

Comparisons of the formaldehyde measurements by Method 323 and Method 320 need to

consider that measurements for both test methods have uncertainty. This section is not intended

to be a rigorous analysis of the measurements uncertainty, but rather to examine the larger

potential sources of error and provide additional context for the methods comparison.

Sampling and analytical imperfections contribute to the uncertainty in EPA Method 323

measurements. For M323, the key QA/QC specifications that are indicators of the measurement

uncertainty include:

• Sample gas volume measured by dry gas meter accurate within 2 percent;

• Sample train leak check less than 2 percent of sample gas flow rate;

• Field duplicates within 20% of mean of duplicate samples;

• Spike sample recovery between 80 and 120 percent; and

• Lab duplicates within 10% of mean of duplicate samples.

The largest of these specifications, field duplicate samples precision and sample spike recovery,

have allowances of 20 percent. A propagation of errors analysis would determine a potential

allowable uncertainty greater than 20 percent.

For EPA Method 320, the formaldehyde calibration gas and QA Spike Recovery are two

indicators of the measurement uncertainty. Formaldehyde is an unstable gas and it is difficult

make a highly accurate calibration gas within the required concentration range. The calibration

gases used for the OK and MS test projects in this report have analytical accuracies of +/- 10%

and +/- 15%, respectively. A third formaldehyde calibration gas, acquired for the WY tests, was

returned to the supplier for reanalysis due to accuracy concerns. This gas was originally

delivered with a formaldehyde concentration of 84.0 ppm and sulfur hexafluoride (SF6)

concentration of 11.4 ppm. As discussed in the test report, field checks determined this

formaldehyde concentration was not accurate. The following summarizes the cylinder

reanalysis:

• Re-analysis upon receipt: 46.2 ppm formaldehyde and 11.4 ppm SF6:

• Rolling the cylinder for 20 minutes and analyzing again: 46.6 ppm formaldehyde and 11.5

ppm SF6: and

• Heating the cylinder for one hour to 50'C and analyzing again: 320 ppm formaldehyde and

11.4 ppm SF6.

The conclusion of the supplier was that the cylinder was exposed to cold weather and some

formaldehyde dropped out. This experience illustrates possible additional uncertainty in the

calibration gas concentrations.
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The QA spike recovery is performed by injecting a slipstream of the calibration gas into the

sample gas line at the probe at a flowrate that is less than 10% of the total resultant sample gas

flow rate. The spike recovery is calculated based on the incremental formaldehyde added to the

sample gas. Equation 1 from EPA Method 321 is used to calculate the spike recovery.

DF * CS

Sm - Su * (1 - DF) %Recovery = 100* M321 Eqn. 1

Where:

Sm = mean concentration of the analyte spiked effluent samples (observed).

DF = Dilution Factor (Total flow/Spike flow).

Total flow = spike flow plus effluent flow.

Cs = cylinder concentration of spike gas.

Su = native concentration of analytes in unspiked samples.

The method requirement for the QA spike recovery is 70 – 130%. Discussion with FTIR

operators (and the experience during the WY testing) indicates that CH2O calibration gases

greater than 30 ppmv are typically not stable and for the tests in MS and OK, the calibration

gases ranged from 20 to 25 ppm; thus, for a spike performed with a 20 ppmv calibration gas at

10% flow, the spike recovery is based on 2 ppmv formaldehyde. Evaluating the spike recovery

data becomes difficult when the native concentration is varying.

Considering an example test scenario with an initial (pre-spike) native concentration of 20 ppmv

and a 20 ppmv calibration gas, a change in the native concentration of about 0.66 ppmv (3.3%

relative change) from the time the native was measured (pre-spike) to the time the spike is

measured corresponds to the +/- 30% recovery allowance. Thus, when lower concentration spike

recoveries are poor and the native formaldehyde concentration is observed to marginally vary

while operating conditions are relatively constant (not uncommon for gas-fired engines), the

cause of the poor recovery could be poor system performance (e.g. sample line losses, analytical

interferences/errors) or an artifact of the native concentration variability. High analytical

accuracies for formaldehyde calibration gases can also contribute to the QA spike recovery

uncertainty.

For the test series conducted in Oklahoma and Wyoming, more rigorous QA spike procedures

(than required by the test method) were implemented in an effort to better evaluate method

performance. In addition to selecting engines running at steady loads and with low variability in

the formaldehyde emissions for the test conditions, the QA spike methodology included native

concentration measurements between each of the three required spike runs – the average of the

pre- and post-spike native concentrations were averaged to minimize the impact of native

concentration changes during the QA spike. In addition, the native and spike measurements

were of sufficiently long duration that emission variability was encompassed and a representative

average determined.
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3.0 Testing Results and Analysis

On-site observation of the OK and WY tests and review of all the test reports and QA/QC results

indicate the measurements were conducted per the test methods and complied with the QA/QC

specifications. The complete field test reports are provided as Attachments.

Table 2 presents the side-by-side Method 323 and Method 320 CH2O measurements. Individual

test run and average formaldehyde measurements are presented for each engine and test

condition. A review of the data indicates:

• As shown in Column I and Column J, the Method 323 measurements were greater than the

Method 320 measurements for all but one of the sixteen test runs.

• Column K shows the absolute difference (in ppmv) between the M323 and M320

formaldehyde measurements and Column L shows the M320/M323 ratio. Based on the test

averages, the M323 measurements were 12 to 47 percent higher than the M320

measurements (M323/M320 ratios are the inverse of Column L ratios).

• Excepting Test Series 2, the M320/M323 measurements ratio was fairly constant (range of

83.4% to 89.3%) and the M320 measurements were on average about 14 percent lower than

the M323 measurements; alternatively, the M323 measurements were on average about 16

percent higher than the M320 measurements.

• Column M lists the average QA Spike Recovery values for the tests. The agreement between

the M320/M323 ratios in Column L with these values suggests a correlation between the low

spike recoveries and the lower M320 measurements. Or, to state another way, quality

assurance checks indicate nominal negative bias in M320 tests that is within accepted

QA/QC criteria. Thus, when comparing M320 to M323 results, higher M323 results would

be expected if M323 measurement did not include this same bias. The ratio of M320 to

M323 results and nominally higher M323 results support this perspective. This issue is

further discussed below.

Table 3 provides further comparison of the M323 and M320 measurements. The measurement

differences from Table 2 are presented and for each Test Series, a t-value based on the paired

measurement differences is calculated and compared to a critical t-value based on an 80 percent

confidence interval (80% CI based on EPA Method 301 methodology) and n-1 degrees of

freedom, with n equal to the number of test runs. Equation 301-9 from EPA Method 301 is used

to calculate the t-value based on the paired measurement differences:

( )

n

STDEV di

davg

t = M301 Eqn. 9

where:

davg – average of the differences between the paired M323 and M320 measurements;

STDEV (di) – standard deviation of the differences between the paired M323 and M320

measurements (di);

n – test runs performed during the test series.
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As shown in Table 3, the calculated t-values are larger than the critical t-values for all five test

series. This indicates the differences between the M323 and M320 CH2O measurements are

significant and, for the data collected for this test project, there appears to be a bias between the

two measurement methods.

In Table 4, the M320 formaldehyde measurements are adjusted using the QA spike recovery

values and the statistical analysis is repeated. QA spike recoveries should not be considered an

absolute measure of the measurement bias (e.g. caused by sample line losses, analytical

interferences, or other factors) because, as discussed above, the spike recovery values are very

sensitive to variations in the native concentrations and calibration gas accuracy, and thus can

have considerable uncertainty. However, for these tests the QA spike recoveries provide an

indication of the measurement bias and the adjustment would be expected to correct the

measured values closer to the “actual” emissions. In addition, as discussed above, more rigorous

QA spike procedures were implemented for Test Series 3, 4, and 5 to reduce the spike recovery

uncertainties.

As shown in Table 4, the t-values are less than the critical t-values for Test Series 1, 2, and 5

indicating the M323 and adjusted M320 average measurements are not statistically different. For

Test Series 3 and 4, the t-values exceed t-critical; however, while the M323 and adjusted M320

measurements would be considered statistically different, they should not be considered

practically different. For Test Series 3, the absolute difference between the M323 and adjusted

M320 measurements is 1 ppmv or less for all three test runs and the relative difference is less

than 2%. These are minuscule differences for field emission measurements, especially

considering the scale of the two test methods uncertainty discussed in section 2.1. For example,

CH2O calibration gases used to calibrate the FTIR have uncertainties of 10 - 15% or more. For

Test Series 4, the average absolute difference between the M323 and adjusted M320

measurements is about 2 ppmv and the relative difference is less than 4%. Once again, these

differences are small relative to the uncertainty of the test methods.
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Table 2. Summary of Method 323 and Method 320 Formaldehyde Measurements.

A B C D E F G H I J K 

O2 M320 CH2O H2O M320 CH2O M323 CH2O M323 - M320 

Test Series Site Unit Test Condition Run % dry ppmvw % ppmvd ppmvd ppmvd 

1 15.3% 25.7 6.4% 27.5 28.5 1.1 2 15.0% 27.6 6.7% 29.6 28.4 -1.0 3 15.5% 20.5 6.2% 21.9 31.6 9.6 4 13.2% 24.2 8.4% 26.4 36.6 10.1 

1 MS CBLSV-16-1

Average 24.5 6.9% 26.3 31.3 4.9 

1 10.3% 27.4 11.1% 30.8 45.2 14.2 2 9.9% 28.6 11.5% 32.3 54.5 22.2 3 9.9% 31.4 11.7% 35.6 45.8 10.3 

2 MS CBLSV-16-2

Average 29.1 11.4% 32.9 48.5 15.6 

1-High 1.3% 36.6 16.8% 44.0 51.6 7.6 2-High 1.4% 37.3 16.8% 44.6 52.9 8.2 3-High 1.3% 36.0 17.6% 43.7 51.6 7.8 

3 OK 80 hp 4SRB High Load/ Low O2

Average 36.6 44.1 52.0 7.9 

1-Mid 2.3% 42.0 16.9% 50.6 58.7 8.0 2-Mid 2.3% 42.0 16.9% 50.6 59.2 8.6 3-Mid 2.4% 41.9 16.8% 50.3 57.3 6.9 

4 OK 80 hp 4SRB Mid Load/ High O2

Average 42.0 50.5 58.4 7.9 

1 8.0% 36.9 12.6% 42.2 47.8 5.6 2 8.0% 37.0 12.6% 42.3 48.5 6.2 3 8.0% 36.9 12.6% 42.2 45.7 3.5 

5 WY Waukesha F18GL

Average 36.9 42.3 47.3 5.1 
Technical Report: Formaldehyde Methods Comparison

May 12, 2010

Table 3. Analysis of Method 323 and Method 320 CH2O Measurement Differences.

Test Run M323 CH2O M320 CH2O M323 - M320

Series

Site Unit

Test

Condition ppmvd ppmvd ppmvd

1 28.5 27.5 1.1

2 28.4 29.6 -1.0

3 31.6 21.9 9.6

4 36.6 26.4 10.1

Average 31.3 26.3 4.9

STDEV 5.8

t value 1.713

1 MS

CB LSV16-1

t crit

A

1.638

1 45.2 30.8 14.2

2 54.5 32.3 22.2

3 45.8 35.6 10.3

Average 48.5 32.9 15.6

STDEV 6.0

t value 4.464

2 MS

CB LSV16-2

t crit

A

1.886

1-High 51.6 44.0 7.6

2-High 52.9 44.6 8.2

3-High 51.6 43.7 7.8

Average 52.0 44.1 7.9

STDEV 0.3

t value 44.433

3 OK

80 hp

4SRB

High Load/

Low O2

t crit

A

1.886

1-Mid 58.7 50.6 8.0

2-Mid 59.2 50.6 8.6

3-Mid 57.3 50.3 6.9

Average 58.4 50.5 7.9

STDEV 0.9

t value 15.754

4 OK

80 hp

4SRB

Mid Load/

High O2

t crit

A

1.886

1 47.8 42.2 5.6

2 48.5 42.3 6.2

3 45.7 42.2 3.5

Average 47.3 42.3 5.1

STDEV 1.4

t value 6.169

5 WY

Waukesha

F18GL

t crit

A

1.886

A. Critical t-value based on 80 percent confidence interval and n-1 degrees of freedom.
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Table 4. Analysis of Method 323 and Method 320 CH2O Measurement Differences with

M320 Data Adjusted for QA Spike Recovery.

Run

M323

CH2O

M320

CH2O

QA Spike

Recovery

M320SR

CH2O

B

M323 -

M320SR

Test

Series

Site Unit

Test

Condition

ppmvd ppmvd % ppmvd ppmvd

1 28.5 27.5 89.3% 30.7 -2.2

2 28.4 29.6 89.3% 33.1 -4.7

3 31.6 21.9 89.3% 24.5 7.0

4 36.6 26.4 89.3% 29.6 7.0

Average 31.3 26.3 89.3% 29.5 1.8

STDEV 6.1

t value 0.586

1 MS

CB LSV16-1

t crit

A

1.638

1 45.2 30.8 73.4% 42.0 3.2

2 54.5 32.3 73.4% 44.0 10.5

3 45.8 35.6 73.4% 48.5 -2.7

Average 48.5 32.9 73.4% 44.8 3.7

STDEV 6.6

t value 0.955

2 MS

CB LSV16-2

t crit

A

1.886

1-High 51.6 44.0 83.6% 52.6 -1.0

2-High 52.9 44.6 83.6% 53.4 -0.5

3-High 51.6 43.7 83.6% 52.3 -0.7

Average 52.0 44.1 83.6% 52.8 -0.8

STDEV 0.2

t value -5.316

3 OK

80 hp

4SRB

High Load/

Low O2

t crit

A

1.886

1-Mid 58.7 50.6 83.4% 60.7 -2.1

2-Mid 59.2 50.6 83.4% 60.7 -1.5

3-Mid 57.3 50.3 83.4% 60.4 -3.1

Average 58.4 50.5 83.4% 60.6 -2.2

STDEV 0.8

t value -4.591

4 OK

80 hp

4SRB

Mid Load/

High O2

t crit

A

1.886

1 47.8 42.2 88.4% 47.8 0.0

2 48.5 42.3 88.4% 47.9 0.6

3 45.7 42.2 88.4% 47.8 -2.1

Average 47.3 42.3 88.4% 47.8 -0.5

STDEV 1.4

t value -0.591

5 WY

Waukesha

F18GL

t crit

A

1.886

A. Critical t-value based on 80 percent confidence interval and n-1 degrees of freedom.

B. M320 CH2O measurements adjusted by dividing QA Spike Recovery.
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4.0 Observations and Considerations for Methods Improvement

Based on observations and discussion with test personnel, the following issues are presented for

consideration for EPA Method 323:

• Recommended best practices would include minimizing the sample line length where

possible;

• Recommended best practices would include ensuring the sample line has no upward sloping

sections where condensation could accumulate;

• Recommended best practices would include pre-test inspection and cleaning of sample lines

to remove possible contaminants and flush with dry air to remove all moisture;

• Recommended best practices would include using more than 10 ml of water for sample

recovery and use of a larger (than 40 ml) VOA vial if necessary to ensure the probe and

sample line are thoroughly rinsed. M323 Section 8.3 states “In general, combined rinse

volumes should not exceed 10 ml [emphasis added].” This statement may lead some testers

to use insufficient water for sample probe and line rinses, especially if the sample location

requires use of a longer sample line.

• It is difficult to accurately measure moisture with M323. Problems include the mass of water

collected is relatively small compared to the typical field scale units, the impingers must be

thoroughly dried on the outside before weighing, and any condensate in the sample line

(impingers weighted prior to sample recovery) will bias the moisture determination low.

Anecdotal observations indicate that combustion exhaust moisture measurements by M323

impinger weights can be inaccurate (e.g. relative to calculated values and other measurement

methods). In addition, weighing the impingers requires disconnecting the sample train prior

to sample recovery which needlessly complicates the recovery and exposes the sample

equipment to atmosphere.

• Based on the Section 12.1 Nomenclature and the description of the spectrophotometer

calibration curve procedure (Section 10.1), Equation 323-5 should be

1,000

1

* * *

Va

Vt

m = Kc A df * rather than

Va

Vt

m = Kc * A* F * ; that is, replace “F” with “df” and

add conversion factor for μg to mg:

g

mg

1,000 μ

1

.

- In Section 12.1 Nomenclature, engineering units should be included with all parameters.

For example, Kc should have units of “μg/(2 ml aliquot - unit absorbance)” based on

Equation 323-5. This will add clarity to minimize the potential for confusion when

developing the calibration curve constant.

Based on observations and discussion with test personnel, the following issues are presented for

consideration for EPA Method 320;

• The equation for QA spike recovery is not included in Method 320; it is in Method 321.

There are QA/QC differences between Method 320 and ASTM Method D6348, and some

testers appear to be incorrectly using an equation, from the ASTM Method to calculate the

QA spike recovery for EPA 320;

• The difficulties of performing the QA spike procedure on emission sources with nominal

variation in native concentrations are discussed in Section 2.1. Issues with this procedure
Technical Report: Formaldehyde Methods Comparison

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(and related concentration of the spike gas) are exacerbated for more variable sources (e.g.,

an engine with cyclic load). EPA Method 321 discusses the use of dual FTIR instruments to

conduct QA spikes if the native concentration is variable (e.g. exceeds 5% or 5 ppmv);

however, most test vans are not equipped with dual systems and this would increase testing

costs. An alternative that may be more practical could be the QA spike procedure in ASTM

Method D 6348, which appears to be better suited for emission sources with variable native

concentrations. However, this method may not be viable for formaldehyde testing on

engines because a CH2O standard with a concentration about ten times the native is required,

and reliable CH2O calibration gases appear to be limited to 30 ppmv or less. Development of

higher concentration CH2O standards would enhance the measurement of CH2O by FTIR.
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5.0 Summary and Conclusions

This report provides the results of side-by-side formaldehyde measurements by Proposed EPA

Method 323 and EPA Method 320. These results support that EPA Method 323 accurately

measures formaldehyde from gas-fired combustion sources and should be published in the

Federal Register as a promulgated method:

• A Method 301 validation study was successfully completed for EPA Method 323 by the Gas

Research Institute. The test method met all the validation criteria, and that performance was

reaffirmed by the recent tests reported herein.

• The anomalous EPA Method 323 measurements from EPA Region 8 have been investigated

and determined to be a result of numerous testing errors – i.e., human error – rather than

problems associated with the test method.

• EPA Method 323 has been used by testers for many years to measure formaldehyde from

gas-fired combustion sources and the preponderance of test data has been accepted as

reliable;

• This test project – which included five test series on four different gas-fired engines –

consistently demonstrated the equivalency of EPA Method 323 formaldehyde measurements

with EPA Method 320 measurements, with results comparing extremely favorably when

M320 results are corrected for a bias identified by the QA spike recovery; and

• The fact that the M323 formaldehyde measurements were consistently higher than the M320

measurements supports the M323 data. Sampling system temperatures are well below the

formaldehyde formation window (e.g. partial CH4 oxidation) and formaldehyde is reactive,

water soluble, and could absorb on sample system surfaces; thus, the potential for low bias is

much greater than the potential for a high bias and the M320 QA spike recoveries provide

evidence that M320 measurements for this test program have a low bias.
Technical Report: Formaldehyde Methods Comparison Attachment A

May 12, 2010

14

Attachment A

Technical Memorandum “EPA Method 323 Emission Test Data and Methodology

Errors from EPA Region 8

i n n o v a t i v e e n v i r o n m e n t a l s o l u t i o n s , i n c .

Technical Memorandum

To: Lisa Beal, INGAA and Stephanie Meadows, API

From: Tom McGrath, Innovative Environmental Solutions, Inc

c: Gary McAlister/EPA, Bob Wayland/EPA, Melanie King/EPA, Hans Buenning/EPA

Region 8, Jeff Panek/IES, Jim McCarthy/IES

Date: October 22, 2009

Subject: EPA Method 323 Emission Test Data and Methodology Errors from EPA Region 8

Introduction

Recent formaldehyde emission test results from numerous gas-fired (IC) internal combustion

engines in EPA Region 8 were significantly lower (i.e. factor of 5 – 10) than historical test

results for these engines. These anomalous test results raised questions regarding the reliability

of EPA Method 323 “Measurement of Formaldehyde Emissions from Natural Gas-Fired

Stationary Sources—Acetyl Acetone Derivitization Method.” As a result, Method 323 was not

included in the proposed revisions to the RICE NESHAP (40 CFR 63 Subpart ZZZZ) as an

option for formaldehyde emission measurements.

In the docket for the recently proposed Subpart ZZZZ rule revisions, document EPA-HQ-OAR2008-0708-0020 discusses questionable test results from the Conoco Philips Sunnyside and

Argenta compressor stations. Review of tests referenced in the rulemaking docket indicated

testing errors rather than methodology as the cause of anomalous results. In addition,

conversations with EPA indicated that there were other questionable test results reported in

Region 8.

Since Subpart ZZZZ requires formaldehyde testing for rich burn engines and extractive FTIR is

the only other viable method, stakeholders are interested in retaining Method 323 if it is

technically acceptable and can meet test method performance objectives. Thus, Innovative

Environmental Solutions Inc. (IES) was tasked to review the basis for EPA’s decision to exclude

Method 323 from Subpart ZZZZ, review potential technical issues, and identify whether technical

evidence supports retaining the method to afford additional compliance testing flexibility for

Subpart ZZZZ. This memo discusses the result of that review and identifies systematic testing

errors, rather than method inadequacies, as the apparent cause for the questionable data reported in
Technical Report: Formaldehyde Methods Comparison Attachment A

May 12, 2010

15

Region 8. This review determined that questionable emission data were collected by a single

testing company which: frequently used a sample rate an order of magnitude or more above the

method maximum; appears to be improperly calculating the analytical calibration curve; and, could

have other introduced other measurement errors that are not evident in the test report (e.g., sample

recovery and sample line configuration, faulty analytical standards).

This memo includes background on the issue and a summary of test report review. In addition,

minor recommendations are provided for clarifying Method 323. An Attachment includes more

detailed discussion on the test report review, data comparisons, and testing deviations.

Method 323 and Comments on the Proposed Rule

Method 323 withdraws a sample from the stack and “bubbles” that sample through a chilled

impinger train (i.e., specialized glassware) containing water. Formaldehyde is absorbed in the

water, which is chemically treated and analyzed. Method 323 is an example of a “wet test

method” and important sampling and analysis parameters for wet methods include the total

sample volume, sample time, sample rate (volume divided by time), and amount (i.e., weight or

mass) of the species collected. When reviewing test reports for wet methods, there are many test

parameters, analytical results, and related calculations that warrant review. Sample rate, sample

volume, and recovered mass of the subject species (i.e., formaldehyde for Method 323) are key

starting points for the test report review. The procedures for Method 323 are standard

approaches for emissions testing. When compared to other “wet test methods”, Method 323 is

relatively simplistic in terms of sampling, sample recovery, and sample analysis.

Revisions to Subpart ZZZZ proposed in March 2009 concluded that Method 323 should be

excluded from the RICE NESHAP because it was not a final test method and performance

questions had been identified. In preparing comments for submittal by the June 2009 deadline,

IES reviewed related background material to identify whether technical comment was warranted.

IES reviewed the emission test reports from the Conoco Philips Sunnyside and Argenta

compressor stations and determined that the sample rate during the tests was approximately an

order of magnitude higher than the maximum sampling rate allowed by the test method (i.e.,

method maximum rate of 0.4 liters per minute (lpm) versus test rate of approximately 4 lpm).

Because the sample rate was well above the method specification, it is speculated that sample

breakthrough occurred (i.e., formaldehyde was not completely absorbed in the impinger solution

due to excessive sample rate) and the measurements were biased low. The emission tests that

appeared to include low bias were all conducted by a single company – referred to as Test

Company A. IES had follow-up conversations with Test Company A test personnel to discuss

whether data transcriptions could have occurred in the report – i.e., the sample volume and rate

were different than reported. Those conversations confirmed the higher sample rate. This

information was provided to EPA when comments were submitted on the Proposed Rule.

Summary of Test Report Review

In addition to the reports in the docket, it was indicated that additional Region 8 test reports

indicated questionable results. Based on discussion with Hans Buenning of EPA Region 8 and

review of numerous test reports, including both the recent “questionable” test data and historical
Technical Report: Formaldehyde Methods Comparison Attachment A

May 12, 2010

16

test data, it appears that all the questionable emission data are from a single emission testing

company – referred to as Test Company A in this memo. Historical test data from other testing

firms are labeled Test Company B and Test Company C. Figure 1 compares EPA Method 323

formaldehyde measurements conducted by Test Company A with Method 323 measurements by

the other companies on thirteen different engines.

The test reports reviewed typically addressed performance tests on engines with catalytic control

(e.g., engines subject to the RICE MACT). In Figure 1, eleven of the thirteen engines included a

catalyst. The two engines with higher emissions, identification numbers SR-E1 and SR-E2, did

not include catalytic control. Figure 1 clearly shows that Test Company A consistently

measured emission levels lower than the other two companies that completed tests on the same

engines. The Attachment provides additional discussion of systematic problems associated with

deviation from Method 323 procedures that contribute to the anomalous results.

0

5

10

15

20

25

BP-C2BP-C7BPTS8-1RC-C201RC-C202RC-C203SRE1SRE2SRE3SRE4SRE5SRE6

Engine ID

p

p

m

v

d

C

H2O

@ 15

%

O2

Company B

Company B

Company C

Company C

Company A

Company A

Company A

Figure 1. Comparison of EPA Method 323 CH2O Emission Measurements Conducted by

Test Company A and Other Testing Companies for Numerous Engines.

These data include emissions from engines with post-combustion controls (i.e. oxidation

catalysts) and engines with no controls. For all the engines, every Test Company A

formaldehyde test result is lower than every formaldehyde measurement conducted by other

companies. Test Company A measurements are consistently lower regardless of parameters that

could impact formaldehyde emissions including engine load and pre-catalyst gas temperature.

Review of the emission test reports indicates that Test Company A frequently used a sample rate

an order of magnitude or more above the maximum specified in Method 323 and that Test

Company A may be incorrectly calculating the analytical calibration curve (i.e. low bias due to

calculation error). These two method deviations were specifically identified for Test Company

A and other procedural deviations could also have occurred. The calibration curve issue is

discussed in the Attachment and related recommendations for test method clarification are

provided below. In addition to method errors identified for Test Company A, minor deviations
Technical Report: Formaldehyde Methods Comparison Attachment A

May 12, 2010

17

were also observed for the other two companies – i.e., sample rate marginally above the method

specification.

Additional review and discussion of the test errors are provided in the Attachment. In summary,

this data review determined that the questionable data are very likely the result of systematic

errors by a single testing firm rather than fundamental flaws with the method. EPA Method 323

has been successfully employed for years for HAP characterizations (e.g., for major HAP facility

determinations), 40 CFR 63 Subpart ZZZZ compliance testing, and state required testing. In

addition, EPA Method 301 validation testing of the acetyl acetone colorimetric method

conducted by Radian Corporation that formed the basis for Method 323 met all the EPA Method

301 validation criteria. Thus, it appears that EPA Method 323 promulgation as an approved test

method and inclusion in the Subpart ZZZZ Final Rule planned for release in 2010 are warranted.

Method 323 procedures are straightforward and consistent with common procedures for wet

chemistry emission measurement test methods. This review indicates that testing errors were

relatively common in the test reports reviewed. Thus, testing companies should be attentive to

method requirements and agency test report review should ensure that method requirements are

followed.

Recommended Modifications to the Test Method

• Equation 323-5 should be

1,000

1

* * *

Va

Vt

m = Kc A df * rather than

Va

Vt

m = Kc * A* F * ; that is,

replace “F” with “df” and add conversion factor for μg to mg:

g

mg

1,000 μ

1

This revision is needed to correct the nomenclature and parameters referenced in the equation.

• In Section 12.1 Nomenclature, Kc should have units of “mg/2 ml aliquot”

This will add clarity to minimize the potential for confusion when developing the calibration

curve constant.

In addition, based on field experience, IES suggests the following method operating practice:

Orient the sample line and the impingers such that condensation in the sample line flows down into

the first impinger; that is, avoid a parallel, upward sloped, or looped sample line that may

contribute to sample line losses due to condensation (with formaldehyde retained in the

condensate) that collects in the line or backflows into the probe. During sample line recovery,

ensure that this sample line configuration is retained to avoid potential sample losses.
Technical Report: Formaldehyde Methods Comparison Attachment A

May 12, 2010

18

Attachment:

Detailed Discussion of Testing Anomalies Identified from

Review of EPA Region 8 Method 323 Test Reports

Method 323 Summary

Method 323 withdraws a sample from the stack and “bubbles” that sample through a chilled

impinger train (i.e., specialized glassware) containing water. Formaldehyde is absorbed in the

water, which is chemically treated and analyzed. Method 323 is an example of a “wet test

method” and important sampling and analysis parameters for wet methods include the total

sample volume, sample time, sample rate (volume divided by time), and amount (i.e., weight or

mass) of the species collected. When reviewing test reports for wet methods, there are many test

parameters, analytical results, and related calculations that warrant review. Sample rate, sample

volume, and recovered mass of the subject species (i.e., formaldehyde for Method 323) are key

starting points for the test report review. The procedures for Method 323 are standard

approaches for emissions testing. When compared to other “wet test methods”, Method 323 is

relatively simplistic in terms of sampling, sample recovery, and sample analysis.

Test Report Review and Measurement Anomalies

The tables below compare Region 8 emission measurements by Test Company A to Method 323

emission data measured by other testing companies on the same engine. For each engine, the

data include emission controls, engine load, pre-catalyst or stack temperature, measured

emissions (3-run average), analytical calibration curve slope, and the average EPA Method 323

sample rate. It should be noted that there was not sufficient time to review all Region 8 test

reports, the test reports include varying levels of detail, and the primary focus was on test reports

questioned by Region 8 personnel; thus, there may be additional reports at Region 8 pertinent to

this analysis. It should also be noted that a detailed quality assurance (QA) review of these test

reports (either Test Company A reports or reports from other testing companies) has not been

completed and that the Method 323 sample rate and the analytical calibration curve slope were

the only test method parameters reviewed for every report. These testing issues were the focus

of the review because they were identified as problem areas where test procedures used in

practice deviated from Method 323 requirements. However, as discussed below, this cursory QA

review identified anomalies in the majority of the tests including incorrect sample rates, full-size

rather than midget impingers, and calculation errors.

The potential impact of a very high sampling rate on the formaldehyde emission measurements

was discussed above for the Test Company A emission test reports from the Conoco Philips

Sunnyside and Argenta compressor stations. In addition, additional review of some emission test

reports determined that Test Company A could be incorrectly calculating the analytical

calibration curve slope and, consequently, the formaldehyde emissions. This calibration issue is

explained here based on our understanding of the information provided in the test reports.
Technical Report: Formaldehyde Methods Comparison Attachment A

May 12, 2010

19

Method 323 equation 323-5, presented below, is used to calculate the mass of formaldehyde in

each sample based on sample absorbance during the colorimetery analysis.

Va

Vt

m = Kc * A* df *

Where: m = mass of formaldehyde in liquid sample (μg);

Kc = spectrophotometer calibration factor, slope of the least squares linear

regression line (μg/2 ml aliquot);

A = measured absorbance of 2 ml aliquot;

df = dilution factor, 1 unless dilution is required to reduce the absorbance into the

calibration range;

Vt = total volume of the impinger catch/rinsate (ml); and

Va = volume of the analyzed sample aliquot (2 ml).

Note that Va is included in the calculation to properly account for sample aliquot size. However,

the report indicates that Test Company A calculates Kc in units of “μg/ml” rather than “μg/2 ml

aliquot”. If the reported units are correct, Test Company A calculations of formaldehyde mass

per sample are a factor of 2 low – i.e., Va should be removed from the equation for Test

Company A calculations. A comparison of the Test Company A least squares linear regression

line slope (Kc) with Kc’s reported by other companies and analytical labs determined that the Kc

for Test Company A is about half of all other values, supporting the supposition that Test

Company A calculations of formaldehyde mass per sample are a factor of 2 low.

Table 1 compares test data collected by Test Company A and another firm, Test Company B, at

the Red Cedar Spring Creek Compressor Station. The data are for three Caterpillar G3516

TALE engines identified as Units C-201, C-202, and C-203. The test reports indicate that these

engines are equipped with post-combustion emission controls (i.e., oxidation catalysts). For the

three engines, the Test Company A emission measurements (CH2O @ 15% O2) are about a

factor of five or more lower than the Test Company B measurements. The Test Company A

Method 323 sample rate is about a factor of 6 or 7 higher than the Test Company B sample rate

and the slope of the Test Company A analytical calibration curve is about half the Test Company

B analytical calibration curves slopes. Operating parameters expected to impact emissions, such

as Engine Load and Pre-Catalyst Temperature, varied little between the tests suggesting that

engine operation did not introduce a significant difference and the difference in the results is due

to a low bias to the Test Company A measurements caused by testing anomalies from excess

sample rate and calibration computational errors. Information on other equipment and

operational parameters and activities that could impact emissions, such as catalyst replacement

and/or maintenance/cleaning, was not provided in the test reports. It should be noted that the

Test Company B sample rate also exceeded the method maximum rate of 0.4 lpm; albeit only by

a relatively small margin of about 0.1 lpm.
Technical Report: Formaldehyde Methods Comparison Attachment A

May 12, 2010

20

Table 1. Emission Data for Red Cedar Spring Creek Compressor Station Engines C-201, C-202, 

Facility

Engine

Make/

Model

Rating

(hp)

Engine

Load

Engine

ID

Emission

Controls

Pre-Cat/

Stack

Temp (°F)

Testing

Company

Test

Date

CH2O

(ppmvd)

O2%

(dry)

CH2

(@ 15

O2

95% OxCat 770 Test Company A 9/24/08 0.58 8.8 0

100% OxCat 796 Test Company B 10/12/07 6.7 7.6 100%

RC-C201

Ox Cat 798 Test Company B 4/1/08 22.4 7.7 

98% OxCat 820 Test Company A 9/24/08 0.77 7.2 0

100% OxCat 792 Test Company B 10/11/07 15.8 10.6 100%

RC-C202

Ox Cat 795 Test Company B 4/1/08 3.2 7.8 

95% OxCat 807 Test Company A 9/24/08 0.53 8.0 0

100% OxCat 815 Test Company B 10/10/07 6.8 10.0 

Spring

Creek

Compressor

Station

CATG3516TALE

1,340

100%

RC-C203

Ox Cat 815 Test Company B 4/1/08 8.7 7.8 

Table 2 compares test data collected by Test Company A and third firm, Test Company C, at the Samson Resour

Compressor Station – South Ignacio Central Delivery Point. The data are for two Waukesha L594LT engines ide

and E2. The test reports indicate that these engines are not equipped with post-combustion controls. The Test C

measurements (CH2O @ 15% O2) for the two engines are five to more than ten times lower than the Test Compa

For both engines, the Test Company A Method 323 sample rate is about a factor of 4 higher than the Test Compa

the slope of the Test Company A analytical calibration curve is about half the Test Company C analytical calibra

Engine load, which is expected to impact emissions, varied little between the tests and the stack gas temperature 

Test Company A tests; thus, if formaldehyde emission differences occurred due to operating conditions, the Test measurements would be expected to be higher because lower combustion temperature typically increases formald

opposite results suggest a low bias to the Test Company A measurements. It should be noted that the Test Comp

also exceeded the method maximum rate of 0.4 lpm, but by a smaller margin than Test Company A tests.
Technical Report: Formaldehyde Methods Comparison Attachment A

May 12, 2010

21

Table 2. Emission Data for Samson Resources Jaques Compressor Station Engines E1 an

Facility

Engine

Make/

Model

Rating

(hp)

Engine

Load

Engine

ID

Emission

Controls

Stack

Temp (°F)

Testing

Company

Test

Date

CH2O

(ppmvd)

O2%

(dry)

CH2O (

15% O2

1,400 92% None 626 Test Company A 3/25/09 3.8 8.0 11,400

SR-E1

None 765 Test Company C 4/1/08 44.0 7.9 22

1,400 92% None 607 Test Company A 3/25/09 5.1 10.3 2

JaquesCompressorStation

WaukeshaL5794LT

1,400 90%

SR-E2

None 771 Test Company C 4/2/08 29.4 8.5 14

Z. Calibration curve was not included in the test report. Calibration data provided by lab on 9/29/09 as typical fo

Table 3 compares test data collected by Test Company A and Test Company C at the Samson Resources Jaques C

South Ignacio Central Delivery Point. The data are for a Waukesha L594LT engine identified as Unit E6. The t

that this engine is equipped with post-combustion controls, an oxidation catalyst. The Test Company A emission 

@ 15% O2) is about a factor of four lower than the Test Company C formaldehyde measurement. The Test Com

sample rate is about a factor of 3.5 higher than the Test Company C sample rate and the slope of the Test Compa

calibration curve is about half the Test Company C analytical calibration curve slope. Operating parameters exp

emissions, such as Engine Load and Pre-Catalyst Temperature, varied little between the tests suggesting a low bi

Company A measurements. Information on other equipment and operational parameters and activities that coul

such as catalyst replacement and/or maintenance/cleaning, was not provided in the test reports. It should be note

Company C sample rate also exceeded the method maximum rate of 0.4 lpm, but by a smaller margin.
Technical Report: Formaldehyde Methods Comparison Attachment A

May 12, 2010

22

Table 3. Emission Data for Samson Resources Jaques Compressor Station Engine E6

Facility

Engine

Make/

Model

Rating

(hp)

Engine

Load

Engine

ID

Emission

Controls

Pre-Cat/

Stack

Temp (°F)

Testing

Company

Test

Date

CH2O

(ppmvd)

O2%

(dry)

CH2

(@ 15

O2)

92% Ox Cat 777 Test Company A 3/25/09 0.78 9.1 0

Jaques CompressorStation

WaukeshaL594LT 1,400 90% SR-E6 Ox Cat 783 Test Company C 4/1/08 3.33 8.2 1

Z. Calibration curve was not included in the test report. Calibration data provided by lab on 9/29/09 as typical f

Table 4 compares test data collected by Test Company A and Test Company C at the Samson Resources Jaques C

South Ignacio Central Delivery Point. The data are for three Waukesha L594LT engines identified as Units E3, E

reports indicate that these engines are equipped with post-combustion controls. For these three engines, the Test 

323 sample rate conforms with the test method while the Test Company C sample rate exceeded the method max

however, the Test Company A emission measurements (CH2O @ 15% O2) are lower than the Test Company C m

factors ranging from about two to six. The slope of the Test Company A analytical calibration curve is about hal

C analytical calibration curve slope. These tests were conducted after the Argenta and Sunnyside Compressor S

discussed with Test Company A personnel and Test Company A apparently corrected the sampling rate. Five of Company A emission measurements are lower than the Test Company C data by more than a factor of two (the e

analytical calibration curve slope / error in the calculated mass of formaldehyde in the samples); thus, these data operating or measurement parameter could be impacting the Test Company A measurements. Operating parame

impact emissions, such as Engine Load and Pre-Catalyst Temperature, varied little between the tests suggesting a 

Company A measurements. Information on other equipment and operational parameters and activities that coul

such as catalyst replacement and/or maintenance/cleaning, was not provided in the test reports. A specific findin

the differences was not identified. However, evidence of method deviations raises questions about other deviatio

occurred but are not evident in the tests reports.
Technical Report: Formaldehyde Methods Comparison Attachment A

May 12, 2010

23

Table 4. Emission Data for Samson Resources Jaques Compressor Station Engines E3, E4, a

Facility

Engine

Make/

Model

Rating

(hp)

Engine

Load

Engine

ID

Emission

Controls

Pre-Cat/

Stack

Temp (°F)

Testing

Company

Test

Date

CH2O

(ppmvd)

O2%

(dry)

CH2O

(@ 15

O2)

92% Ox Cat 763 Test Company A 5/28/09 1.97 7.6 095% Ox Cat 756 Test Company C 11/19/08 9.18 7.8 492%

SR-E3

Ox Cat 767 Test Company C 4/1/08 11.0 8.1 5

92% Ox Cat 777 Test Company A 5/28/09 1.71 7.3 094% Ox Cat 787 Test Company C 11/19/08 10.2 7.7 592%

SR-E4

Ox Cat 762 Test Company C 4/1/08 9.44 7.8 4

90% Ox Cat 780 Test Company A 5/28/09 2.95 7.8 93% Ox Cat 780 Test Company C 11/19/08 7.37 8.1 3

Jaques

Compressor

Station

Waukesha

L594LT 1,400

90%

SR-E5

Ox Cat 780 Test Company C 4/1/08 4.75 7.7 2

Z. Calibration curve was not included in the test report. Calibration data provided by lab on 9/29/09 as typical fo

Table 5 compares test data collected by Test Company A and Test Company B at two BP America Production C

The data are for two 1,334 hp Waukesha L7042GL engines identified as Units C-2 and C-7 at the Salvador Comp

1,090 hp Waukesha 5790 GL engine at the Treating Site #8 Compressor Station. The test reports indicate that th

equipped with post-combustion emission controls (i.e. oxidation catalysts). For five of the seven Test Company 

engines, the Method 323 sample rate is about a factor of 5 higher than the Test Company B sample rate. For fou

the Test Company A emission measurements (CH2O @ 15% O2) are a factor of ten or more lower. For the fifth 

Compressor Station Unit C-7, the Test Company A measurements were about half the Test Company B measurethe Test Company A tests were conducted after the Argenta and Sunnyside Compressor Stations’ test data were dCompany A personnel (6/18/09 tests) and Test Company A apparently reduced the sampling rate; however, the Temissions are still an order of magnitude or more lower than the Test Company B measurements. The slope of th

analytical calibration curve is about half the Test Company B analytical calibration curve slope with the exceptio
Technical Report: Formaldehyde Methods Comparison Attachment A

May 12, 2010

24

the Treating Station #8 engine. These data suggest, consistent with the above discussion, that something other than 

incorrect analytical calibration curve could be impacting the Test Company A measurements. Review of expecte

parameter impacts do not explain the difference. However, Test Company A systematic deviations from method 

serious questions their results. It should be noted that the Test Company B sample rate also exceeded the method 

0.4 lpm; albeit only by about 0.1 lpm.

Table 5. Emission Data for BP America Production Company Engines.

Facility

Engine

Make/

Model

Engine

ID

Rating

(hp)

Engine

Load

Emission

Controls

Pre-Cat/

Stack

Temp (°F)

Testing

Comp.

Test

Date

CH2O

(ppmvd)

O2

(%dry)

C

(p

@ 

75% 704 Test Company A 7/30/08 0.74 10.0 78% 736 Test Company A 1/8/09 0.13 9.5 85% 706 Test Company A 6/18/09 0.41 7.8 

BP-C-2 1,334

54%

Ox Cat

569 Test Company B 5/30/07 4.1 10.4 

60% 654 Test Company A 7/30/08 3.68 10.3 85% 596 Test Company A 6/18/09 0.21 8.0 

Salvador

Compressor

Station

Waukesha

L7042GL

BP-C-7 1,334

75%

OxCat

577 Test Company B 5/31/07 7.9 9.4 

60% 706 Test Company A 6/10/08 1.03 11.4 65% 601 Test Company A 2/6/09 0.1 9.9 

Treating Site

#8Compressor

Station

Waukesha

5790 GL

BPTS8-1 1,090

75%

Ox Cat

787 Test Company B 8/1/07 15.3 9.6 
Technical Report: Formaldehyde Methods Comparison Attachment A

May 12, 2010

25

Summary and General Observations on Test Method

Over a wide variety of engines and wide range of operating loads and pre-catalyst and stack gas

temperatures, Test Company A formaldehyde measurements were consistently lower than

Method 323 measurements performed by other testing firms. Very high sampling rates and

potential calculation errors likely contributed to the low bias for many of the tests. However,

after Test Company A made some corrections to their sampling approach, their results continued

to exhibit an apparent low bias. This could be due to other method deviations that are not

apparent from the test report.

Test Company A is not the only testing company that is conducting Method 323 with notable

method deviations. In addition to the EPA Region 8 data, IES reviewed numerous EPA 323 test

reports submitted to State of Colorado DPH&E and State of Wyoming DEQ. A general

observation was that the majority of the M323 emission tests were not performed in accordance

with the method. The most common method deviation, observed for a majority of the test

reports reviewed, was that the sampling rate exceeded the test method maximum of 0.4 liters per

minute. Typical sample rates (for companies other than Test Company A) ranged from 0.5 to 1.0

lpm. Another common method deviation was the use of sample trains configured with full size

EPA Method 5 impingers. In addition, many test reports were incomplete such that the emission

data could not be verified; for example, field data sheets and/or equipment calibrations were not

included in the report. As noted above, the procedures for Method 323 are “ordinary”, yet

method deviations were common. This indicates that testing companies and agency reviewers of

test plans and test reports need to be more attentive to ensure proper methods are followed.

In addition, IES review identified issues with Method 323 that require clarification.

Recommended corrections and clarifications are discussed in the memo.
Technical Report: Formaldehyde Methods Comparison Appendix B

May 12, 2010

26

Attachment B

Pertinent Correspondence and Test Reports

Bruce Nemet of Resolution Analytics, Inc. - (919) 774-5557 - provided the following

suggestions for method improvement

1) Sec 11.2.2 refers to the analysis of reagent water. This procedure can be eliminated, in my

opinion, because the analysis of a field blank (Sec 8.4.3) includes both the tester's on-site reagent

water as well as the lab's reagent water used in the derivitizing solution. The lab's reagent water

can be tested separately if a "hit" is observed on the field blank analysis greater than 50 percent

of the lowest calibration standard to determine source of contamination. This, however, is a rare

circumstance and can be eliminated from the procedure on a routine basis.

2) The QA/QC specifications (Sec 8.4) do not include the requirement for a field spike

preparation and analysis. Formaldehyde is a "delicate" analyte in aqueous solution without

preservation treatment and Chris Knott (of Oasis Emission Consultants, Inc.) and I both agree

that a field spike is necessary to determine any analyte degradation in the field samples and

should be a requirement of the method.

Test Reports

The following test reports from the testing companies are provided as separate documents:

• Attachment B1_ LSV Feb 2010 test report-Final_041510.pdf. This report includes the

Method 323 and Method 320 test reports for the MS engines.

• Attachment B2_bp-10-hinton[1].ok-ftir_1-rpt_032310.pdf. This report includes the Method

320 test reports for the OK engine.

• Attachment B3_10-0059_CHK_API_CH2O_InhouseRPTR1.pdf. This report includes the

Method 323 test reports for the OK engine.

• Attachment B4_M323_4SLB_F18GL_HCOH_March 18,2010_REV3.pdf. This report

includes the Method 323 test reports for the WY engine.

• Attachment B5_ M320_4SLB_F18GL_HCOH_March 18,2010_REV1.pdf. This report

includes the Method 320 test reports for the WY engine.