July 1999
Environmental Technology
Verification Report
ECOM A-PLUS
Portable Emission Analyzer
Prepared by
0
Baiteiie
. , . Putting Technology To Work
Battelle Memorial Institute
Under a cooperative agreement with
wcfiA U.S. Environmental Protection Agency
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July 1999
Environmental Technology Verification
Report
Advanced Monitoring Systems
ECOM A-PLUS
Portable Emission Analyzer
By
Thomas Kelly
Ying-Liang Chou
Susan J. Abbgy
Paul I. Feder
James J. Reuther
Karen Riggs
Battelle
Columbus, Ohio 43201
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Notice
The U.S. Environmental Protection Agency (EPA), through its Office of Research and Develop-
ment has financially supported and collaborated in the extramural program described here. This
document has been peer reviewed by the Agency and recommended for public release. Mention of
trade names or commercial products does not constitute endorsement or recommendation by the
EPA for use.
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Foreword
The U.S. Environmental Protection Agency (EPA) is charged by Congress with protecting the
Nation's air, water, and land resources. Under a mandate of national environmental laws, the
Agency strives to formulate and implement actions leading to a compatible balance between
human activities and the ability of natural systems to support and nurture life. To meet this
mandate, the EPA's Office of Research and Development (ORD) provides data and science
support that can be used to solve environmental problems and to build the scientific knowledge
base needed to manage our ecological resources wisely, to understand how pollutants affect our
health, and to prevent or reduce environmental risks.
The Environmental Technology Verification (ETV) Program has been established by the EPA,
to verify the performance characteristics of innovative environmental technology across all media
and to report this objective information to permitters, buyers, and users of the technology, thus
substantially accelerating the entrance of new environmental technologies into the marketplace.
Verification Organizations oversee and report verification activities based on testing and Quality
Assurance protocols developed with input from major stakeholders and customer groups
associated with the technology area. At present, there are twelve environmental technology areas
covered by ETV. Information about each of the environmental technology areas covered by ETV
can be found on the Internet at http://www.epa.gov/etv.htm.
Effective verifications of monitoring technologies are needed to assess environmental quality, and
to supply cost and performance data to select the most appropriate technology for that
assessment. In 1997, through a competitive cooperative agreement, Battelle Memorial Institute
was awarded EPA funding and support to plan, coordinate, and conduct such verification tests,
for "Advanced Monitoring Systems for Air, Water, and Soil" and report the results to the
community at large. Information concerning this specific environmental technology area can be
found on the Internet at http://www.epa.gov/etv/07/07_main.htm.
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Acknowledgments
The authors wish to acknowledge the support of all those who helped plan and conduct the
verification test, analyze the data, and prepare this report. In particular we recognize Joseph
Tabor, Steve Speakman, and Joshua Finegold of Battelle, and Drew Wilson and Brock Pulliam of
ECOM America, Ltd.
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Contents
Notice ii
Foreword vii
Acknowledgments viii
List of Abbreviations xiv
1 Background 1
2 Technology Description 2
3 Test Design and Procedures 4
3.1 Introduction 4
3.2 Laboratory Tests 5
3.2.1 Linearity 7
3.2.2 Detection Limit 8
3.2.3 Response Time 8
3.2.4 Interrupted Sampling 8
3.2.5 Interferences 8
3.2.6 Pressure Sensitivity 9
3.2.7 Ambient Temperature 10
3.3 Combustion Source Tests 11
3.3.1 Combustion Sources 11
3.3.2 Test Procedures 12
4 Quality Assurance/Quality Control 16
4.1 Data Review and Validation 16
4.2 Deviations from the Test/QA Plan 16
4.3 Calibration of Laboratory Equipment 18
4.4 Standard Certifications 18
4.5 Performance System Audits 19
4.5.1 Internal Audits 19
4.5.2 External Audit 22
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5. Statistical Methods 24
5.1 Laboratory Tests 24
5.1.1 Linearity 24
5.1.2 Detection Limit 25
5.1.3 Response Time 26
5.1.4 Interrupted Sampling 26
5.1.5 Interferences 26
5.1.6 Pressure Sensitivity 27
5.1.7 Ambient Temperature 27
5.2 Combustion Source Tests 28
5.2.1 Accuracy 28
5.2.2 Zero/Span Drift 28
5.2.3 Measurement Stability 28
5.2.4 Inter-Unit Repeatability 29
5.2.5 Data Completeness 29
6. Statistical Results 30
6.1 Laboratory Tests 30
6.1.1 Linearity 30
6.1.2 Detection Limit 37
6.1.3 Response Time 38
6.1.4 Interrupted Sampling 40
6.1.5 Interferences 40
6.1.6 Pressure Sensitivity 42
6.1.7 Ambient Temperature 42
6.1.8 Zero and Span Drift 45
6.2 Combustion Source Tests 46
6.2.1 Relative Accuracy 46
6.2.2 Zero and Span Drift 49
6.2.3 Measurement Stability 51
6.2.4 Inter-Unit Repeatability 51
6.3 Other Factors 51
6.3.1 Cost 55
6.3.2 Data Completeness 55
6.3.3 Maintenance/Operational Factors 55
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7. Performance Summary 56
8. References 57
Appendix A: Data Recording Sheets A-l
Appendix B: External Technical Systems Audit Report B-l
Figures
Figure 2-1. ECOM A-PLUS 2
Figure 3-1. Manifold Test Setup 7
Figure 6-1. Results of First NO Linearity Test on ECOM Unit B 36
Tables
Table 3-1. Identity and Schedule of Verification Tests Conducted on
ECOM A-PLUS Analyzers 4
Table 3-2. Summary of Interference Tests Performed 9
Table 3-3. Span Concentrations Provided Before and After Each Combustion Source .... 14
Table 4-1. Results of QC Procedures for Reference NOx Analyzers for Testing ECOM
A-PLUS Verification Analyzers 17
Table 4-2. Equipment Type and Calibration Date 18
Table 4-3. Observations and Findings From the Internal Technical Systems Audit 20
Table 4-4. Performance Evaluation Results 21
Table 6-la. Data from NO Linearity Test Over 0-4,000 ppm Range for ECOM
A-PLUS Analyzers 31
Table 6-lb. Data from N02 Linearity Test Over 0-500 ppm Range for ECOM A-PLUS
Analyzers 32
Table 6-lc. Data from NO Linearity Test Over 0-1,000 ppm Range for
ECOM Analyzers 33
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Table 6-ld. Data from N02 Linearity Test Over 0-200 ppm Range for
ECOM Analyzers 34
Table 6-2a. Statistical Results for First Linearity Tests with ECOM Analyzers (1/17/99) ... 34
Table 6-2b. Statistical Results for Second Linearity Test with ECOM Analyzers 2/18/99) . . 35
Table 6-3a. Estimated Detection Limits From First Linearity Test (1/17/99),
for the ECOM Analyzers 37
Table 6-3b. Estimated Detection Limits From Second Linearity Test (2/18/99),
for the ECOM Analyzers 37
Table 6-4. Response Time Data for ECOM A-PLUS Analyzers 39
Table 6-5. Lower Limits of Response Times Estimated for ECOM A-PLUS Analyzers ... 39
Table 6-6. Data from Interrupted Sampling Test with ECOM A-PLUS Analyzers 40
Table 6-7. Pre- to Post-Test Differences as a Result of Interruption of Operation
of ECOM A-PLUS Analyzers 40
Table 6-8. Data from Interference Tests on ECOM A-PLUS Analyzers 41
Table 6-9. Results of Interference Tests of ECOM A-PLUS Analyzers 41
Table 6-10. Data from Pressure Sensitivity Test for ECOM A-PLUS Analyzers 43
Table 6-11. Pressure Sensitivity Results for ECOM A-PLUS Analyzers 43
Table 6-12. Data from Ambient Temperature Test of ECOM A-PLUS Analyzers 44
Table 6-13. Ambient Temperature Effects on ECOM A-PLUS Analyzers 44
Table 6-14. Data from Linearity and Ambient Temperature Tests Used to Assess
Zero and Span Drift of the ECOM A-PLUS Analyzers 45
Table 6-15. Zero and Span Drift Results for the ECOM A-PLUS Analyzers 46
Table 6-16a. Data from Gas Rangetop in Verification of ECOM A-PLUS
Analyzers 47
Table 6-16b. Data from Gas Water Heater in Verification of ECOM A-PLUS
Analyzers 47
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Table 6-16c. Data from the Diesel Generator at High RPM in Verification
of ECOM A-PLUS Analyzers 48
Table 6-16d. Data from the Diesel Generator at Idle in Verification
of ECOM A-PLUS Analyzers 48
Table 6-17. Relative Accuracy of ECOM A-PLUS Analyzers 49
Table 6-18. Data Used to Assess Zero and Span Drift for ECOM A-PLUS Analyzers on
Combustion Sources 50
Table 6-19. Results of Zero and Span Drift Evaluation for ECOM A-PLUS Analyzers .... 50
Table 6-20. Data from Extended Sampling Test with Diesel Generator at Idle,
Verification of ECOM A-PLUS Analyzers 52
Table 6-21. Results of Evaluation of Measurement Stability for
ECOM A-PLUS Analyzer 54
Table 6-22. Summary of Repeatability 54
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List of Abbreviations
AC
alternating current
AMS
Advanced Monitoring Systems
ANSI
American National Standards Institute
Btu/hr
British thermal unit per hour
ccm
cubic centimeter per minute
CEMS
continuous emission monitoring system
CO
carbon monoxide
co2
carbon dioxide
DC
direct current
EPA
U.S. Environmental Protection Agency
ETV
Environmental Technology Verification
FID
flame ionization detector
ft3
cubic feet
gpm
gallons per minute
kW
kilowatt
LOD
limit of detection
1pm
liters per minute
m3
cubic meters
nh3
anhydrous ammonia
NIST
National Institute of Standards and Technology
NO
nitric oxide
NOx
nitrogen oxides
no2
nitrogen dioxide
02
oxygen
PE
performance evaluation
ppm
parts per million, volume
ppmC
parts per million carbon
QA
quality assurance
QC
quality control
QMP
Quality Management Plan
rms
root-mean-square
RPM
revolutions per minute
SAS
Statistical Analysis System
XIV
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SCAQMD South Coast Air Quality Management District
SCR selective catalytic reduction
S02 sulfur dioxide
UHP ultra-high purity
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Chapter 1
Background
The U.S. Environmental Protection Agency (EPA) has created the Environmental Technology
Verification Program (ETV) to facilitate the deployment of innovative environmental technologies
through performance verification and dissemination of information. The goal of the ETV Program
is to further environmental protection by substantially accelerating the acceptance and use of
improved and cost-effective technologies. ETV seeks to achieve this goal by providing high
quality, peer reviewed data on technology performance to those involved in the design,
distribution, permitting, purchase and use of environmental technologies.
ETV works in partnership with recognized testing organizations, stakeholder groups consisting of
regulators, buyers and vendor organizations, and with the full participation of individual
technology developers. The program evaluates the performance of innovative technologies by
developing test plans that are responsive to the needs of stakeholders, conducting field or
laboratory tests (as appropriate), collecting and analyzing data, and preparing peer reviewed
reports. All evaluations are conducted in accordance with rigorous quality assurance protocols to
ensure that data of known and adequate quality are generated and that the results are defensible.
The EPA's National Exposure Research Laboratory and its verification organization partner,
Battelle Memorial Institute, operate the Advanced Monitoring Systems (AMS) program under
ETV. The AMS program has recently evaluated the performance of portable nitrogen oxides
monitors used to determine emissions from combustion sources. This verification statement
provides a summary of the test results for the ECOM A-PLUS Portable Emission Analyzer.
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Chapter 2
Technology Description
The objective of the ETV Advanced Monitoring Systems pilot is to verify the performance
characteristics of environmental monitoring technologies for air, water, and soil. This verification
report provides results for the verification testing of the ECOM A-PLUS electrochemical NO and
N02 analyzer, manufactured by ECOM America, Ltd., Norcross, Georgia. The following is a
description of the ECOM A-PLUS analyzers, based on information provided by the vendor.
The ECOM A-PLUS (Figure 2-1) is a portable, microprocessor controlled, electrochemical
sensor-based emission analyzer. The ECOM A-PLUS can be fitted with up to five separate gas
sensors to measure oxygen, carbon monoxide, oxides of nitrogen (NO and N02), and sulfur
dioxide. The A-PLUS measures 21" x 10" x 11.8" and weighs 30 pounds.
The ECOM A-PLUS is designed for a variety of applications: boiler/burner flue gas analysis;
engine emissions analysis; pollution source testing; and environmental reporting of stack gas
parameters, among others. Measuring ranges are oxygen (02), 0.0 percent to 21.0 percent; carbon
monoxide (CO), 0 to 4,000 ppm and/or 0 to 40,000 ppm; nitric oxide (NO), 0 to 4,000 ppm;
nitrogen dioxide (N02), 0 to 500 ppm; and sulfur dioxide (S02), 0 to 4,000 ppm. The A-PLUS
also measures gas and ambient temperatures and stack
draft (pressure) and will perform a standardized smoke
test. The calculated parameters include carbon dioxide
(C02), combustion efficiency, excess air, and losses.
Only the NO and N02 measurement capabilities were
verified in the tests reported here.
An on-board printer allows hard copy printing of vital
stack parameters, while an RS232 interface provides
the option to store the data to a computer. Windows-
based data acquisition software is available. The A-
PLUS incorporates a sample conditioning system that
includes a heated sample line, heated probe head,
peltier cooler, and moisture removal assembly. This
system cools and dries the gas sample, providing the
gas sensors with a stable sample of gas (i.e.,
temperature/humidity), to aid the long-term stability
and reliability of the instrument.
Figure 2-1. ECOM A-PLUS
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Designed for semi-continuous operation, the ECOM A-PLUS is not recommended for continuous
gas emission measurement.
In all verification testing reported here, two ECOM A-PLUS analyzers, designated as units A and
B, were operated simultaneously. The performance of each analyzer was verified independently;
however, results from the two analyzers were compared to assess unit-to-unit repeatability.
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Chapter 3
Test Design and Procedures
3.1 Introduction
The verification test described in this report was conducted in January and February 1999 on
commercial portable nitrogen oxides analyzers. The tests were conducted at Battelle in Columbus,
Ohio, according to procedures specified in the Test/QA Plan for Verification of Portable NO/NO 2
Emission Analyzers(A ) Verification testing of the analyzers involved the following tests:
1. A series of laboratory tests in which certified NO and N02 standards were used to
challenge the analyzers over a wide concentration range under a variety of conditions.
2. Tests using three realistic combustion sources, in which data from the analyzers
undergoing testing were compared to chemiluminescent NO and NOx measurements made
following the guidelines of EPA Method 7E.(2)
The schedule for the ECOM A-PLUS tests is shown in Table 3-1.
Table 3-1. Identity and Schedule of Verification Tests Conducted on ECOM A-PLUS
Analyzers
Test Activity Date Conducted
Laboratory Tests
Linearity* January 17, 1999, p.m. and Februaryl9, 1999, a.m.
Interrupted Sampling January 17, p.m. to January 18, a.m.
Interferences January 18, a.m.
Pressure Sensitivity January 18, a.m.
Ambient Temperature* February 18, p.m.
* The ECOM analyzers were damaged due to an overheating of the test chamber during the high temperature
test on January 18, 1999; this test and the source tests were completed February 17-19, after repairing the
analyzers. A repeat of the linearity test was also conducted at that time over reduced ranges for NO and N02.
Source Tests
Gas Rangetop
Gas Water Heater
Diesel Generator High RPM
Diesel Generator-Idle
February 17, a.m.
February 17, a.m.
February 19, a.m.
February 19, a.m.
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To assess inter-unit variability, two identical ECOM A-PLUS analyzers were tested
simultaneously. These two analyzers were designated as Unit A and Unit B throughout all testing.
The commercial analyzers were operated at all times by a representative of ECOM so that each
analyzer's performance could be assessed without concern about the familiarity of Battelle staff
with the analyzers. At all times, however, the ECOM representative was supervised by Battelle
staff. Displayed NO and N02 readings from the analyzers (in ppm) were manually entered onto
data sheets prepared before the test by Battelle. Battelle staff filled out corresponding data sheets,
recording, for example, the challenge concentrations or reference analyzer readings, at the same
time that the analyzer operator recorded data. This approach was taken because visual display of
measured NO and N02 (or NOx) concentrations was the "least common denominator" of data
transfer among several N0/N02 analyzers tested. Copies of the blank data recording sheets used
by Battelle and vendor staff are included as Appendix A of this report.
Verification testing began with ECOM staff setting up and checking out their two analyzers in the
laboratory at Battelle. Once vendor staff were satisfied with the operation of the analyzers, the
laboratory tests were begun. These tests were carried out in the order specified in the test/QA
plan.(1) Upon completion of laboratory tests, the analyzers were moved to a nearby building where
the combustion sources described below were set up, along with two chemiluminescent nitrogen
oxides monitors which served as the reference analyzers. The combustion source tests were
conducted indoors, with the combustion source exhausts vented through the roof of the test
facility. This arrangement assured that testing was not interrupted and that no bias in testing was
introduced as a result of the weather. Sampling of source emissions began with the combustion
source emitting the lowest NOx concentration and proceeded to sources emitting progressively
more NOx. In all source sampling, the analyzers being tested sampled the same exhaust gas as did
the reference analyzers. This was accomplished by inserting the ECOM analyzers' gas sampling
probes into the same location in the exhaust duct as the reference analyzers' probe.
3.2 Laboratory Tests
The laboratory tests were designed to challenge the analyzers over their full nominal response
ranges, which for the ECOM A-PLUS analyzers were 0 to 4,000 ppm for NO and 0 to 500 ppm
for N02. These nominal ranges exceed the actual NO or N02 concentrations likely to be emitted
from most combustion sources. Nevertheless, the lab tests were aimed at quantifying the full
range of performance of the analyzers.
Laboratory tests were conducted using certified standard gases for NO and N02, and a gas
dilution system with flow calibrations traceable to the National Institute of Standards and
Technology (NIST). The NO and N02 standards were diluted in high purity gases to produce a
range of accurately known concentrations. The NO and N02 standards were EPA Protocol
1 gases, obtained from Scott Specialty Gases, of Troy, Michigan. As required by the EPA
Protocol(3) the concentration of these gas standards was established by the manufacturer within
1 percent accuracy using two independent analytical methods. The concentration of the NO
standard (Scott Cylinder Number ALM 057210) was 3,925 ppm, and that of the N02 standard
(Scott Cylinder Number ALM 019660) was 493.2 ppm. These concentrations were confirmed in a
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performance evaluation audit conducted near the end of the verification tests by comparison with
independent standards obtained from other suppliers.
The gas dilution system used was an Environics Model 2020 mass flow controlled diluter (Serial
Number 2108). This diluter incorporated four separate mass flow controllers, having ranges of 10,
10, 1, and 0.1 1pm, respectively. This set of flow controllers allowed accurate dilution of gas
standards over a very wide range of dilution ratios, by selection of the appropriate flow con-
trollers. The mass flow calibrations of the controllers were checked against a NIST standard by
the manufacturer prior to the verification test, and were programmed into the memory of the
diluter. In verification testing, the Protocol Gas concentration, inlet port, desired output concen-
tration, and desired output flow rate were entered by means of the front panel keypad of the 2020
diluter, and the diluter then set the required standard and diluent flow rates to produce the desired
mixture. The 2020 diluter indicated on its front panel display the actual concentration being
produced, which in some cases differed very slightly from the nominal concentration requested. In
all cases the actual concentration produced was recorded as the concentration provided to the
analyzers undergoing testing. The 2020 diluter also provided warnings if a flow controller was
being operated at less than 10 percent of its working range, i.e., in a flow region where flow
control errors might be enhanced. Switching to another flow controller then minimized the
uncertainties in the preparation of the standard dilutions.
Dilution gases used in the laboratory tests were Acid Rain CEM Zero Air and Zero Nitrogen from
Scott Specialty Gases. These gases were certified to be of 99.9995 percent purity, and to have the
following maximum content of specific impurities: S02 <0.1 ppm, NOx <0.1 ppm, CO < 0.5
ppm, C02 < 1 ppm, total hydrocarbons <0.1 ppm, and water < 5 ppm. In addition the nitrogen
was certified to contain less than 0.5 ppm of oxygen, while the air was certified to contain 20 to
21 percent oxygen.
Laboratory testing was conducted primarily by supplying known gas mixtures to the analyzers
from the Environics 2020, using a simple manifold that allowed the two analyzers to sample the
same gas. The experimental setup is shown schematically in Figure 3-1. The manifold itself
consisted of a 9.5-inch length of thin-walled 1-inch diameter 316 stainless steel tubing, with
1/4-inch tubing connections on each end. The manifold had three 1/4-inch diameter tubing side
arms extending from it: two closely spaced tubes are the sampling points from which sample gas
was withdrawn by the two analyzers, and the third provided a connection for a Magnehelic
differential pressure gauge (±15 inches of water range) that indicated the manifold pressure
relative to the atmospheric pressure in the laboratory. Gas supplied to the manifold from the
Environics 2020 always exceeded by at least 0.5 1pm the total sample flow withdrawn by the two
analyzers. The excess vented through a "T" connection on the exit of the manifold, and two
coarse needle valves were connected to this "T," as shown in Figure 3-1. One valve controlled the
flow of gas out the normal exit of the manifold, and the other was connected to a small vacuum
pump. Closing the former valve elevated the pressure in the manifold, and opening the latter valve
reduced the pressure in the manifold. Adjustment of these two valves allowed close control of the
manifold pressure within a target range of ±10 inches of water, while maintaining excess flow of
the gas mixtures to the manifold. The arrangement shown in Figure 3-1 was used in all laboratory
tests, with the exception of interference testing. For most interference testing,
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Figure 3-1. Manifold Test Setup
gas standards of the appropriate concentrations were supplied directly to the manifold, without
use of the Environics 2020 diluter.
Laboratory testing consisted of a series of separate tests evaluating different aspects of analyzer
behavior. The procedures for those tests are described below, in the order in which the tests were
actually conducted. The statistical procedures that were applied to the data from each test are
presented in Chapter 5 of this report.
3.2.1 Linearity
The linearity of analyzer response was tested by wide-range multipoint calibrations with NO and
N02. Linearity testing consisted of a 21-point response check for NO, and for N02. Prior to this
check, the ECOM analyzers were provided with the appropriate zero gas, and then with an NO or
N02 span gas concentration near the respective nominal full scale of the analyzers (i.e., near
4,000 ppm NO or 500 ppm N02). The actual values of the span gases provided were 3,925 ppm
NO and 493.2 ppm N02. After adjustments to the analyzers to accurately match that span value,
the 21-point check proceeded without further adjustments. The 21 points consisted of three
replicates each at 10, 20, 40, 70, and 100 percent of the nominal range, in randomized order, and
interspersed with six replicates of zero gas.(1) Following completion of all 21 points, the zero and
100 percent spans were repeated, also without adjustment of the analyzers. This entire procedure
was performed for NO and then for N02. Throughout the linearity test, the analyzer indications of
both NO and N02 concentrations were recorded, even though only NO or N02 were supplied to
the analyzers. This procedure provided data to assess the cross-sensitivity to NO and N02.
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When the ECOM analyzers were returned to complete the verification testing, a second linearity
test was conducted at the request of ECOM. This second test covered ranges of 1,000 ppm NO
and 200 ppm N02, but was otherwise identical to the 21-point procedure described above.
3.2.2 Detection Limit
Data from zero gas and from 10 percent of full-scale points in the linearity test were used to
establish the NO and N02 detection limits of the analyzers, using a statistical procedure defined in
the test/QA plan.(1)
3.2.3 Response Time
During the NO and N02 linearity tests, upon switching from zero gas to an NO or N02
concentration of 70 percent of the respective full scale (i.e., about 2,100 ppm NO or 350 ppm
N02), the analyzers' responses were recorded at 10-second intervals until fully stabilized. These
data were used to determine the response times for NO and for N02, defined as the time to reach
95 percent of final response after switching from zero gas to the calibration gas.
3.2.4 Interrupted Sampling
After the zero and span checks that completed the linearity test, the ECOM analyzers were shut
down (i.e., their electrical power was turned off overnight), ending the first day of laboratory
testing. The next morning the analyzers were powered up, and the same zero gas and span
concentrations were run without adjustment of the analyzers. Comparison of the NO and N02
zero and span values before and after shutdown indicated the extent of zero and span drift
resulting from the shutdown. Near full-scale NO and N02 levels (i.e., 3,925 ppm NO and
493.2 ppm N02) were used as the span values in this test.
3.2.5 Interferences
Following analyzer startup and completion of the interrupted sampling test, the second day of
laboratory testing continued with interference testing. This test evaluated the response of the
ECOM analyzers to species other than NO and N02. The potential interferants listed in Table 3-2
were supplied to the analyzers one at a time, and the NO and N02 readings of the analyzers were
recorded. The potential interferants were single components, except for a mixture of S02 and NO,
which was intended to assess whether S02 in combination with NO produced a bias in NO
response.
The CO, C02, S02, and NH3 mixtures used in the interference test were all obtained as Certified
Master Class Calibration Standards from Scott Technical Gases, at the concentrations indicated in
Table 3-2. The indicated concentrations were certified by the manufacturer to be accurate within
± 2 percent, based on analysis. The CO, C02, and NH3 mixtures were all in Ultra-High Purity
(UHP) air, and the S02 mixture was in UHP nitrogen. The S02/NO mix listed in Table 3-2 was
prepared by diluting the S02 standard with the NO Protocol Gas using the Environics 2020.
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Table 3-2. Summary of Interference Tests Performed
Interferant
Interferant
Concentration
CO
496 ppm
co2
5.03%
so2
501 ppm
494 ppm
485 ppm Cx, 98 ppm C2,
48 ppm C3 + C4
451 ppm S02 + 388 ppm NO
nh3
Hydrocarbon Mixture*
S02 and NO
* C| = methane; C2 = ethane; and C3 + C4 = 24 ppm propane + 24 ppm n-butane.
The hydrocarbon mixture listed in Table 3-2 was prepared at Battelle in UHP hydrocarbon-free
air, starting from the pure compounds. Small quantities of methane, ethane, propane, and n-
butane were injected into a cylinder that was then pressurized with UHP air. The required
hydrocarbon concentrations were approximated by the preparation process, and then quantified by
comparison with aNIST standard containing 8.61 ppm carbon (ppmC) in the form of propane.
Using a gas chromatograph with a flame ionization detector (FID) the NIST standard was first
analyzed twice, producing peak areas of 18,627 and 18,791 area units per 8.61 ppmC of propane.
The average FID response factor (18,709 units (±116 units)/8.61 ppmC) was then used to
determine the concentrations of the components of the prepared hydrocarbon mixture. Two
analyses of that mixture both gave a result of 485 ppm methane; the corresponding results for
ethane were 97 and 98 ppm; for propane 23 and 24 ppm; and for n-butane 24 and 25 ppm.
In the interference test, each interferant in Table 3-2 was provided individually to the sampling
manifold shown in Figure 3-1, at a flow in excess of that required by the two analyzers. Each
period of sampling an interferant was preceded by a period of sampling the appropriate zero gas.
3.2.6 Pressure Sensitivity
The pressure sensitivity test was designed to quantify the dependence of analyzer response on the
pressure in the sample gas source. By means of two valves at the downstream end of the sample
manifold (Figure 3-1), the pressure in the manifold could be adjusted above or below the ambient
room pressure, while supplying the manifold with a constant ppm level of NO or N02 from the
Environics dilution system. This capability was used to determine the effect of the sample gas
pressure on the sample gas flow rate drawn by the analyzers, and on the NO and N02 response.
The dependence of sample flow rate on pressure was determined using an electronically timed
bubble flow meter (Ultra Flow Primary Gas Flow Calibrator, Model 709, Serial No. 010928;
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SKC, Inc.). This flow meter was connected in line (i.e., inserted) into the sample flow path from
the manifold to one of the commercial analyzers. Zero gas was supplied to the manifold at
ambient pressure, and the analyzer's sample flow rate was measured with the bubble meter. The
manifold pressure was then adjusted to -10 inches of water relative to the room, and the
analyzer's flow rate was measured again. The manifold pressure was adjusted to +10 inches of
water relative to the room, and the flow rate was measured again. The bubble meter was then
moved to the sample inlet of the other commercial analyzer, and the flow measurements were
repeated.
The dependence of NO and N02 response on pressure was determined by sampling the appro-
priate zero gas, and an NO or N02 span gas equivalent to about 70 percent of the respective full
scale, at each of the same manifold pressures (room pressure, -10 inches, and +10 inches). This
procedure was conducted simultaneously on both analyzers, first for NO at all three pressures,
and then for N02 at all three pressures. The data at different pressures were used to assess zero
and span drift resulting from the sample pressure differences. The actual NO and N02 span
concentrations used were 2,600 ppm and 350 ppm, respectively.
3.2.7 Ambient Temperature
The purpose of the ambient temperature test was to quantify zero and span drift that may occur as
the analyzers are subjected to different temperatures during operation. This test involved provid-
ing both analyzers with zero and span gases for NO and N02 (at 700 ppm and 140 ppm con-
centrations, respectively) at room, elevated, and reduced temperatures. A temperature range of 7
to 41 °C (45 to 105°F) was targeted in this test. The elevated temperature condition was achieved
using a 1.43 m3 steel and glass laboratory chamber, thermostated at 105 °F using external heat
lamps. The reduced temperature condition was achieved using a conventional domestic
refrigerator (Crosley Model CT19A5W) with a refrigerator volume of 13.1 ft3.
The general procedure was to provide zero and span gas for NO, and then for N02, to both
analyzers at room temperature, and then to place both analyzers and the sampling manifold into
the heated chamber. Electrical and tubing connections were made through a small port in the
lower wall of the chamber. A thermocouple readout was used to monitor the chamber tempera-
ture and room temperature, and the internal temperature indications of the analyzers themselves
were monitored, when available. After 1 hour or more of stabilization in the heated chamber, the
zero and span tests were repeated. The analyzers, manifold, and other connections were then
transferred to the refrigerator. After a stabilization period of 1 hour or more, the zero and span
checks were repeated at the reduced temperature. The analyzers were returned to the laboratory
bench; and, after a stabilization period, the zero and span checks were repeated a final time.
In conducting the ambient temperature test on the ECOM analyzers, the analyzers were
inadvertently damaged due to accidental overheating in the heated chamber. After being repaired
at ECOM, the analyzers were returned to Battelle to complete the verification testing, and the
ambient temperature test was repeated in its entirety.
10
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3.3 Combustion Source Tests
3.3.1 Combustion Sources
Three combustion sources (a gas rangetop, a gas residential water heater, and a diesel engine)
were used to generate NOx emissions from less than 10 ppm to nearly 500 ppm. Emissions
databases for two of these sources (rangetop and water heater) exist as a result of prior
measurements, both of which have been published.(4'5)
3.3.1.1 Rangetop
The low-NOx source was a residential natural gas fired rangetop (KitchenAid Model 1340),
equipped with four cast-iron burners, each with its own onboard natural gas and combustion air
control systems. The burner used (front-left) had a fixed maximum firing rate of about 8 KBtu/hr.
The rangetop generated NO in the range of about 4 to 8 ppm, and N02 in the range of about 1 to
3 ppm. The database on this particular appliance was generated in an international study in which
15 different laboratories, including Battelle, measured its NO and N02 emissions.(4)
Rangetop NOx emissions were diluted prior to measurement using a stainless-steel collection
dome, fabricated according to specifications of the American National Standards Institute (ANSI
Z21.1).(6) For all tests, this dome was elevated to a fixed position 2 inches above the rangetop
surface. Moreover, for each test, a standard "load" (pot) was positioned on the grate of the
rangetop burner. This load was also designed according to ANSI Z21.1 specifications regarding
size and material of construction (stainless steel). For each test, the load contained 5 pounds of
room-temperature water.
The exit of the ANSI collection dome was modified to include seven horizontal sample-probe
couplers. One of these couplers was 1/4-inch in size, three were 3/8-inch in size, and three were
1/2-inch in size. Their purpose was to accommodate various sizes of vendor probes and one
reference probe simultaneously during combustion-source sampling.
This low-NOx combustion source was fired using "standard" natural gas, obtained from Praxair,
Inc., which was certified to contain 90 percent methane, 3 percent ethane, and the balance
nitrogen. This gaseous fuel contained no sulfur.
3.3.1.2 Water Heater
The medium-NOx source was a residential natural gas-fired water heater (Ruud Model P40-7) of
40-gallon capacity. This water heater was equipped with one stamped-aluminum burner with its
own onboard natural gas and combustion air control systems, which were operated according to
manufacturer's specifications. The burner had a fixed maximum firing rate of about 40 KBtu/hr.
Gas flow to the water heater was monitored using a calibrated dry-gas meter.
The water heater generated NO emissions in the range of 50 to 70 ppm, and N02 in the range of 5
to 10 ppm. NOx emissions dropped as the water temperature rose after ignition, stabilizing at the
11
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levels noted above. To assure constant operation of the water heater, a continuous draw of 3 gpm
was maintained during all verification testing. The database on this particular appliance was
generated in a national study in which six different laboratories measured its emissions, including
Battelle.(5)
Water heater NOx emissions were not diluted prior to measurement. The draft hood, integral to
the appliance, was replaced with a 3-inch diameter, 7-inch long stainless-steel collar. The exit of
this collar was modified to include five horizontal sample-probe couplers. One coupler was 1/4-
inch in size, whereas the two other pairs were either 3/8- or 1/2-inch in size. Their purpose was to
accommodate various sizes of vendor probes and one reference probe simultaneously during
sampling.
This medium-NOx combustion source was fired on house natural gas, which contained odorant-
level sulfur (4 ppm mercaptan). The composition of this natural gas is essentially constant, as
monitored by a dedicated gas chromatograph in Battelle's laboratories.
3.3.1.3 Diesel Engine
The high-NOx source was an industrial diesel 8 kW electric generator (Miller Bobcat 225D Plus),
which had a Deutz Type ND-151 two-cylinder engine generating 41 KBtu/hr (16 horsepower).
This device generated NOx emissions over a range of about 150 to 450 ppm, depending on the
load on the super-charged engine. High load (3,500 RPM) resulted in the lowest NOx; idle
(2,000 RPM) resulted in the highest NOx. At both conditions, about one-third of the NOx was
N02. The database on the diesel generator emissions was generated in tests conducted in the
2 weeks prior to the start of the verification tests.
NOx emissions from this engine were not diluted prior to measurement. The 1-inch exhaust outlet
of the engine, which is normally merely vented to the atmosphere, was fitted with a stack designed
to meet the requirements of the U.S. EPA (Method 5).(9) The outlet was first expanded to 2 inches
of 1.5-inch diameter copper tubing, then to 15 inches of 2-inch diameter copper tubing, and finally
to 2 inches of 3-inch diameter copper tubing. The 3-inch diameter tubing was modified to include
five horizontal sample-probe couplers. One of these couplers was 1/4-inch in size, two were 3/8-
inch in size, and two were 1/2-inch in size. These couplers held the sample probes in place. The
3-inch tube was connected to a 3-inch stack extending through the roof of the test laboratory.
This high-NOx combustion source was fired on commercial diesel fuel, which, by specification,
contains only 0.03 to 0.05 weight percent sulfur.
3.3.2 Test Procedures
The procedures followed during combustion source testing consisted of those involved with the
sampling systems, reference method, calibration gas supply, and the sources, as follows.
12
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3.3.2.1 Sampling Systems
Prior to sampling, the ECOM representative inserted two of its product's probes into the exhaust
duct of the rangetop, water heater, or diesel engine. The ECOM probes were fitted one above the
other, sampling from a point within about 1/4 inch of the inlet of the reference analyzers' probe.
The reference analyzer probe consisted of a 26-inch long, 1/4-inch diameter stainless-steel tube,
the upstream 2 inches of which were bent at a right angle for passage into the center of the source
exhaust duct. Each combustion source had a dedicated sampling probe, connected to the
reference analyzers with 1/4-inch tubing. The lengths of sample-transfer tubing required to
connect vendor instruments to the rangetop, water heater, and diesel engine were about 4 feet,
4 feet, and 8 feet, respectively. The lengths of sample-transfer tubing required to connect
reference instruments to the rangetop, water heater, and diesel engine were about 7 feet, 9 feet,
and 4 feet, respectively.
The ECOM analyzers were operated during source testing with their integral sample transfer lines
and sampling filtering and drying devices. Neither the reference sampling probe nor the reference
sample-transfer lines were heated. Visible condensation of combustion-generated water did not
occur. The reference analyzer moisture-removal system consisted of a simple ice bath (0°C,
32 °F). The reference particulate-removal system consisted of a 47-millimeter in-line quartz filter.
3.3.2.2 Reference Method
The reference method of NO determination against which the vendor analyzers were compared
was the ozone chemiluminescence method for NO that forms the basis of EPA Method 7E.(2) The
reference measurements were made using a Model 10 and a Model 14A source-level NOx monitor
(both from Thermo Environmental Instruments), located side-by-side near the combustion
sources. These monitors sampled from a common intake line and operated on identical ranges of
100 ppm or 1,000 ppm full scale, depending on the source. Both instruments use stainless steel
catalytic converters maintained at 650°C (1,202°F) for reduction of N02 to NO for detection.
Digital electronic voltmeters were connected directly to the amplifier output of the monitors, to
provide direct digital display of the data. The Model 10 and 14A monitors provide sequential,
rather than simultaneous, measurement of NO and NOx, so display of both readings required
manual switching of sampling modes on both instruments. This requirement resulted in the NO
and NOx readings from the reference analyzers being separated in time by about 15 seconds, due
to the stabilization needed after switching. This effect is believed to have negligible impact on the
verification results due to the stability of source emissions.
The chemiluminescence analyzers were calibrated using the Environics Series 100 and the EPA
Protocol 1 gases. The calibration procedure was specified in the test/QA plan, and required
calibration at zero, 30 percent, 60 percent, and 100 percent of the applicable range value (i.e., 100
or 1,000 ppm). Calibration results closest in time to the verification source test were used to
establish scale factors applicable to the source test data. The conversion efficiency of the stainless
steel converters was determined by calibrating with both NO and N02 on the applicable ranges,
using the EPA Protocol 1 gases. The ratio of the linear regression slope of the N02 calibration to
that of the NO calibration determined the N02 conversion efficiency. For the ECOM source tests,
13
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which took place on February 17 and 19, 1999, calibration data from February 16 were applied.
Conversion efficiency values of 94.5 percent and 94.1 percent were found for the Model 14A and
Model 10 monitors, respectively, and all reference analyzer results were corrected to account for
these conversion efficiencies.
3.3.2.3 Calibration Gas Supply
Before and after sampling of each combustion source, both the analyzers undergoing testing and
the reference analyzers were supplied with zero gas and with standard NO and N02 mixtures at
levels comparable to those expected from the source. To prepare these mixtures, Protocol 1 gases
identical to those used in the laboratory testing were diluted using an Environics Series 100
Computerized Multi-Gas Calibrator (Serial Number 2416). The same Acid Rain CEM zero gases
were used for dilution and zeroing as were used in the laboratory tests. When low dilution ratios
were required for some calibration points, Tylan FC-260 (3 1pm) and FC-280 (5 1pm) mass flow
controllers were used instead of the Environics calibrator. The Tylan flow controllers were
calibrated using the same SKC electronic bubble flow meter used in the laboratory tests, and were
operated with a Tylan four-unit control and readout device. The pre- and post-test span values
used with each combustion source are given in Table 3-3.
At the request of the ECOM representative, the ECOM analyzers were calibrated before any
source testing using 50 ppm NO and 30 ppm N02 standards, prepared as described above. No
adjustment was made to the ECOM analyzers when sampling the span gas indicated in Table 3-3
for the two gas combustion sources.
Table 3-3. Span Concentrations Provided Before and After Each Combustion Source
Source
NO Span Level (ppm)
N02 Span Level (ppm)
Gas Rangetop
20
10
Gas Water Heater
100
15
Diesel-High RPM
200
50
Diesel-Idle
400
100
The pre- and post-test zero and span values were used to assess the drift in zero and span
response of the reference and tested analyzers caused by exposure to source emissions.
3.3.2.4 Operation of Sources
Verification testing was conducted with the combustion sources at or near steady-state in terms of
NOx emission. For the rangetop, steady-state was achieved after about 15 minutes, when the
water began to boil. For the water heater, steady-state was achieved in about 15 minutes, when its
14
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water was fully heated. Because the water heater tank had a thermostat, cycling would have
occurred had about 3 gpm of hot water not been continuously drained out of the tank.
For the diesel engine, steady-state was achieved in about 10 minutes of operation. The diesel was
operated first at full speed (3,500 RPM) to achieve its lowest NOx emissions. Prior to sampling
the NOx emissions at idle, the diesel engine was operated at idle for about 20 minutes to
effectively "detune" its performance.
The order of operation of the combustion sources was (1) rangetop, (2) water heater, (3) diesel
engine (high RPM), and (4) diesel engine (idle). This allowed the analyzers to be exposed to
continuously increasing NO and N02 levels, and avoided interference in low level measurements
that might have resulted from prior exposure to high levels.
Sampling of each combustion source consisted of obtaining nine separate measurements of the
source emissions. After sampling of pre-test zero and span gases provided from the calibration
source, and with both the reference and vendor analyzers sampling the source emissions, the
ECOM operator indicated when he was ready to take the first set of readings (a set of readings
consisting of the NO and N02 response on both Units A and B). At that time the Battelle operator
of the reference analyzers also took corresponding readings. The analyzers undergoing testing
were then disconnected from the source, and allowed to sample room air until readings dropped
well below the source emissions levels. The analyzers were then reconnected to the source, and
after stabilizing another set of readings was taken. There was no requirement that analyzer
readings drop fully to zero between source measurements. This process was repeated until a total
of nine readings had been obtained with both the vendor and reference analyzers. The same zero
and span gases were then sampled again before moving to the next combustion source.
One addition to this procedure was the extended sampling test, conducted as the last operation in
the combustion source testing. This test involved continuous sampling of the diesel engine
emissions for a full hour with no intervals of room air sampling. Data were recorded for both
reference and vendor analyzers at 1-minute intervals throughout that hour of measurement. This
test was conducted only after nine sequential sets of readings had been obtained from all the
combustion sources by the procedure described above.
15
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Chapter 4
Quality Assurance/Quality Control
Quality control (QC) procedures were performed in accordance with the quality management plan
(QMP) for the AMS pilot(7) and the test/QA plan(1) for this verification test.
4.1 Data Review and Validation
Test data were reviewed and approved according to the AMS pilot QMP, the test/QA plan, and
Battelle's one-over-one approval policy. The Verification Testing Leader reviewed the raw data
and data sheets that were generated each day and approved them by adding his signature and date.
Laboratory record notebooks were also reviewed, signed, and dated by the Verification Testing
Leader.
Other data review focused upon the compliance of the chemiluminescent reference analyzer data
with the quality requirements of Method 7E. The purpose of validating reference data was to
ensure usability for the purposes of comparison with the analyzers undergoing verification. The
results of the review of the reference analyzer data quality are shown in Table 4-1. The data
generated by the reference analyzers were used as a baseline to assess the performance of the
technologies for N0/N02 analysis.
4.2 Deviations from the Test/QA Plan
During the physical set up of the verification test, deviations from the test/QA plan were made to
better accommodate differences in vendor equipment, availability of Battelle personnel and
equipment, and other changes or improvements. Any deviation required the approval signature of
Battelle's Verification Testing Leader and the pilot manager. A planned deviation form was used
for documentation and approval of the following changes:
1. Dr. Agnes Kovacs did not participate in the statistical analysis of data from the verification
test.
2. The order of testing was changed, and a span value of 70 percent of range (rather than
100 percent) was used in the pressure sensitivity test.
3. The order of the ambient temperature test was changed.
4. The exact concentrations used in the mixture of S02 and NO for the interference test were
changed.
5. A different diesel generator was used than that originally planned.
6. An oxygen sensor was not used during source tests.
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7. Thermo Environmental Models 14A/10 NO/NOx analyzers were used for reference method.
8. Triplicate calibration points were not run on reference method analyzers.
9. Unheated sample line and tubing were used, based on Battelle's previous experience in
sampling of the combustion sources used in this test and other similar sources.
Table 4-1. Results of QC Procedures for Reference NOx Analyzers for Testing
ECOM A-PLUS Analyzers
N02 conversion
efficiency
N02 conversion
efficiency
Calibration of reference
method using four points
at 0, 30, 60, 100% for
NO
Calibration of reference
method using four points
at 0, 30, 60, 100% for
N02
Calibrations
(100 ppm range)
Zero drift
94.5% for Model 14A in 100
ppm and 1,000 ppm ranges
94.1% for Model 10 in 100 ppm
and 1,000 ppm ranges
Meets criteria
(r2 > 0.9999)
Meets criteria
(r2 > 0.9999)
Meet ± 2% requirement (relative
to span)
Unit 10
Unit 14A
Interference check
Meets ± 3% requirement
(relative to span)
Rangetop Test
Rangetop Test
Water Heater Test
Water Heater Test
Diesel Engine Test (High RPM)
Diesel Engine Test (High RPM)
Diesel Engine Test (Low RPM)
Diesel Engine Test (Low RPM)
< ± 7% (No interference response
NO
NO
Error, % of
%of
Error, % of
%of
Span
Scale
Span
Scale
0.3%
30%
0.6%
30%
0.1%
60%
<0.1%
60%
no2
no2
Error, % of
%of
Error, % of
%of
Span
Scale
Span
Scale
0.3%
30%
0.1%
30%
<0.1%
60%
0.2%
60%
Unit 10
<
±3%
Unit 14A < ± 3%
Unit 10 > 3% on NO span (see text)
Unit 14A < ± 3%
Unit 10 < ± 3%
Unit 14A < ± 3%
Unit 10 < ± 3%
Unit 14A < ± 3%
detected)
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There was one undocumented deviation. Due to a delay in the arrival of the protocol gases used
in the verification test, Battelle was not able to run one instrument through the entire test
sequence prior to verification testing. The impact of this deviation on the final data is described in
the Performance System Audits section of this report.
4.3 Calibration of Laboratory Equipment
Equipment used in the verification test required calibration before use. Equipment types and
calibration dates are listed in Table 4-2. Documentation for calibration of the following equipment
was required before use in the verification test, and was maintained in the test file.
Table 4-2. Equipment Type and Calibration Date
Calibration Date/
Equipment Type
Temperature Check
Flow Controllers (Gas Dilution System) Environics Series 100
6/11/98
Flow Controllers (Gas Dilution System) Environics Model 2020
12/16/98
Digital Temperature Indicator Model 402A
1/7/99
Dwyer Magnahelic Pressure Gauge
1/11/99
Model R-275 In-line Dry Gas Meter
1/11/99
Doric Trendicator 400A Thermocouple Temperature Sensor
1/18/99
Model DTM-115 Reference Dry Gas Meter
9/22/98
4.4 Standard Certifications
Standard or certified gases were used in all verification tests, and certifications or analytical data
were kept on file to document the traceability of the following standards:
# EPA Protocol Gas Nitrogen Dioxide
# EPA Protocol Gas Nitric Oxide
# Certified Master Class Calibration Standard Sulfur Dioxide
# Certified Master Class Calibration Standard Carbon Dioxide
# Certified Master Class Calibration Standard Ammonia
# Certified Master Class Calibration Standard Carbon Monoxide
# Nitrogen Acid Rain CEM Zero
# Acid Rain CEM Zero Air
# Battelle-Prepared Organics Mixture.
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All other QC documentation and raw data for the verification test are located in the test file at
Battelle, to be retained for 7 years and made available for review if requested.
4.5 Performance System Audits
Internal and external performance system audits were conducted and the results are summarized
in the following sections.
4.5.1 Internal Audits
Three internal audits were conducted during verification testing. A technical systems audit was
conducted to assess the physical setup of the test, a performance evaluation audit was conducted
to evaluate the accuracy of the measurement system, and an audit of data quality was conducted
on 10 percent of all data generated during the verification test. A summary of the results of these
audits is provided below.
4.5.1.1 Techni cal Sy stem s Audit
A technical systems audit is a qualitative onsite audit of the physical setup of the test. The
auditors determine the compliance of testing personnel with the test/QA plan. A self-assessment is
required for each test as outlined in the AMS pilot QMP. The QA/QC Reviewer for the
verification test conducted the internal technical systems audit on January 18, 1999, by reviewing
data obtained prior to the ECOM tests reported here. Observations and findings from this audit
are listed in Table 4-3.
4.5.1.2 Performance Evaluation Audit
The performance evaluation audit was a quantitative audit in which measurement standards were
independently obtained and compared with those used in the verification test to evaluate the
accuracy of the measurement system. One such assessment was conducted by Battelle QA staff on
February 4, 1999. No independent assessments of this type were conducted by EPA staff.
The performance evaluation (PE) samples were NO and N02 calibration gases independent of the
test calibration standards containing certified concentrations of NO andN02. Accuracy of the
reference analyzers was determined by comparing the measured N0/N02 concentrations using the
verification test standards with those obtained using the certified PE values. Percent difference
was used to quantify the accuracy of the results. The PE sample for NO was an EPA protocol gas
having nearly the same concentration as the NO standard used in verification testing, but
purchased from a different commercial supplier. The PE standard for N02 was a commercial
standard of 50.5 ppm N02 in air, whose concentration had been confirmed by comparison with a
50 ppm standard reference material of NO in nitrogen, obtained from the National Institute of
Standards and Technology. Table 4-4 summarizes the reference method performance evaluation
results. Included in this table are the performance acceptance ranges and the certified gas
concentration values. The acceptance ranges are guidelines established by the provider of the PE
materials to gauge acceptable analytical results. As shown in Table 4-4, all of the observed
concentrations were well within the acceptance ranges.
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Table 4-3. Observations and Findings From the Internal Technical Systems Audit
Observation/Finding
Corrective Action/Impact on Final Data
Method 7E calibration was not completed prior to
verification testing. Analyzers gave unreliable results
during first test, which prompted a calibration on
1/13/99. Full four-point calibration was not
performed until 1/15/99 on the 0-100 range and
1/16/99 on the 0-1000 range for both Models 14A
and 10. All criteria meet stated objectives in Method
7E for the calibration (linearity, calibration error)
performed on the 15th and 16th.
From Pressure Sensitivity Test conducted 1/12/99 an
explanation is needed of correction factor to be
applied to data.
Start and stop time for instruments to equilibrate at
each temperature is not noted on data sheets.
Calibration drift for all data reviewed is less than
± 3% relative to the span except Model 10 span post-
test on 1/14/99 for diesel engine test which = 3.6%.
Data for test should be flagged at minimum.
Data and calculations for calibration drift test not
found on test data sheets. Recommend a better system
be implemented for assessing quality of the
calibration drift for reference analyzers immediately
following collection of test data so decision whether
or not to proceed is clear to all participants.
Zero/span values are documented on diesel engine
test data sheets for all tests except on 01-13-98 post-
test blank with no explanation.
Vendor source testing that was conducted prior to the
first full four-point Method 7E calibration was
repeated at a later date. Thus all vendor testing was
conducted with fully calibrated reference analyzers.
There is no impact on verification data because the
first vendor test was repeated after Method 7E
calibration was implemented.
The 02 sensors of the vendor's analyzers showed the
presence of 02 in the sample gas at a time when only
NO in pure N2 was being provided to the analyzers.
This indicated a leakage of air into the sample
manifold (which was at reduced pressure relative to
the room). The amount of dilution caused by the
leakage of air was calculated from the 02 level
observed, and exactly accounted for an apparently
low NO response from the vendor's analyzers. That
is, the 02 data were used to correct the observed NO
responses to what they would have been with no air
leakage. The leak was fixed, and no impact exists in
any test data.
Added start and stop time to data sheets as a method
to document equilibration.
All source tests with the ECOM analyzers met a
slightly expanded drift requirement (see text). No
impact on final data.
Comparison of drift is easily made visually; written
comments will be added if termination of a test is
called for.
This test was terminated. Notes were added as
suggested and the test was later repeated in its
entirety. No impact on ECOM data
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Table 4-4. Performance Evaluation Results
Reading (V)
Zero (V)
Zero Corrected
Apparent
Concentration*
Percent
Difference**
Limits
Unit 14A
Test Std
NO in N2
(ppm)
3,925
9.92
0.01
9.91
3905.3
0.5%
±2%
PE Std
3,988
10.13
0.01
10.12
Unit 10
Test Std
NO in N2
(ppm)
3,925
1.01
-0.01
1.03
3895.7
0.7%
±2%
PE Std
3,988
1.04
-0.01
1.05
Unit 14A
Test Std
N02 in
Air (ppm)
50.0***
4.40
0.01
4.39
48.7
2.5%
±5%
PE Std
50.5
4.56
0.02
4.54
Unit 10
Test Std
N02 in
Air (ppm)
50.0***
0.44
-0.01
0.45
50.0
0.1%
±5%
PE Std
50.5
0.44
-0.01
0.45
Concentration of Test Standard indicated by comparison to the Performance Evaluation Standard
**Percent difference of apparent concentration Relative to Test Standard concentration.
***Prepared by dilution of 493.2 ppm N02 Protocol Gas.
4.5.1.3 Audit of Data Quality
The audit of data quality is a qualitative and quantitative audit in which data and data handling are
reviewed and data quality and data usability are assessed. Audits of data quality are used to
validate data at the frequency of 10 percent and are documented in the data audit report. The goal
of an audit of data quality is to determine the usability of test results for reporting technology
performance, as defined during the design process. Validated data are reported in the ETV
verification reports and ETV verification statement along with any limitations on the data and
recommendations for limitations on data usability.
The QA/QC Reviewer for the verification test audited 10 percent of the raw data. Test data sheets
and laboratory record books were reviewed, and calculations and other algorithms were verified.
Calibration drift test results were calculated and compared to the Method 7E criteria. Calculations
that were used to assess the four-point calibration of the reference method were also verified to be
correct.
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Review of vendor and reference method data sheets revealed the following discrepancy which
may have an impact on data quality for the ECOM tests:
1. Relative accuracy test 2/17/99 using water heater, NO reading on Model 10 pre-test span
check = 0.950 V ppm and post-test span check =1.000 V, implying a drift of 4.4 percent
of full scale (after zero correction).
This item is noted in Table 4-1, which summarizes the reference method data quality for the
ECOM verification test. The span drift noted in this instance exceeded the Method 7E criterion of
±3 percent of scale. However, certain departures from strict Method 7E procedures were required
in this verification test, which argue for a slightly wider allowable tolerance on span drift. Those
departures are detailed in the QC test file for this verification effort; a brief summary follows.
Method 7E calls for using undiluted gas standards equal to the full- and mid-scale points on the
analyzer's measurement range. A drift in span of ±3 percent of scale is allowed over the course of
a source emission measurement. This ±3 percent allowable drift is that attributed to the analyzer
itself, since the undiluted standards are assumed not to change over the brief duration of a source
measurement. In contrast, in this verification test, gas standards were diluted using precision mass
flow controllers to achieve the wide range of span gases required. This dilution process
necessarily introduces additional uncertainty of up to about 1.4 percent (i.e., the root-mean-
square error resulting from two flow controllers each with 1 percent random error). As a result,
we estimate an allowable drift of about 4.4 percent, by adding the additional uncertainty noted
above to the 3 percent stated in Method 7E. The drift value noted in Table 4-1 is within this
allowable drift criterion, and no adverse impact on the ECOM test data is inferred.
4.5.2 External Audit
EPA conducted an on-site technical systems audit during the verification testing. This audit was
conducted to observe and evaluate whether the verification team followed the test/QA plan. The
external technical systems audit report is attached in Appendix B and the assessment is
summarized below.
The auditors assessed the verification test procedures and personnel against the Quality Manage-
ment Plan for the ETV Advanced Monitoring Systems Pilot,(7) the Test/QA Plan for Verification
of Portable NO/NO 2 Emission Analyzers,(1) and U.S. EPA Method 7E Determination of Nitrogen
Oxides Emissions from Stationary Sources (Instrumental Analyzer Procedure) {2) The auditors
were on site from January 20, 1999, through January 21, 1999. The technical systems audit was
performed on the flow rate and ambient temperature laboratory tests and the relative accuracy
tests with the gas rangetop, water heater, and a portion of the high RPM emissions of the diesel
generator. No performance evaluations were conducted as a part of this audit.
This external technical systems audit showed that the verification test was well managed,
particularly considering its complexity. All personnel appeared to be well trained for their
particular duties. All involved showed enthusiasm and ingenuity during the verification testing.
Personnel were very familiar with the test/QA plan. With one exception, differences for this
verification test from the original test/QA plan were well documented by deviation reports on file
22
-------
at Battelle. The deviation report format includes a date, cites the deviation, provides an explana-
tion of the deviation, and requires a Battelle approval signature. It was impressive that the
deviation reports were present and were completed up front.
Two major findings resulted from this external technical systems audit. First, as a result of a delay
in the arrival of the protocol gases used in the verification test, Battelle was not able to run one of
the instruments through the test sequence prior to the first test. This undocumented deviation was
from Section 5.6 of the test/QA plan, Test Schedule, and stated "To avoid bias in testing of the
first analyzers through the sequence, Battelle's personnel will first conduct the entire test
sequence using an analyzer already on hand at Battelle. Testing will then continue with analyzers
named in Section 2.4." Second, the test/QA plan states that "The chemiluminescent monitors to
be used for Method 7E reference measurements will be subjected to a four-point calibration with
NO prior to the start of verification testing, on each measurement range to be used for
verification." The combustion source tests were started on January 13, 1999. No four-point
calibration with NO was recorded in the combustion source testing laboratory notebook prior to
January 13. This finding is also a finding in Battelle's internal audit conducted during the first
week of the verification test.
The impact of these two findings on the data presented in this report is as follows. Although
Battelle did not run an instrument through the entire test sequence prior to initiating testing, each
component of the test system was checked independently. Therefore, the absence of this pre-test
check will not impact the final data. The lack of initial calibration of the reference analyzers does
not affect the ECOM A-PLUS data since the appropriate calibration was performed before
combustion source testing with the ECOM analyzers.
23
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Chapter 5
Statistical Methods
5.1 Laboratory Tests
The analyzer performance characteristics were quantified on the basis of statistical comparisons of
the test data. This process began by converting the spreadsheet files that resulted from the data
acquisition process into data files suitable for evaluation with Statistical Analysis System (SAS)
software. The following statistical procedures were used to make those comparisons.
5.1.1 Linearity
Linearity was assessed by linear regression with the calibration concentration as the independent
variable and the analyzer response as the dependent variable. Separate assessments were carried
out for each ECOM analyzer. The calibration model used was
where Yc is the analyzer's response to a challenge concentration c, h(c) is a linear calibration
curve, and the error term was assumed to be normally distributed. (If the variability is not
constant throughout the range of concentrations then weighting in the linear regression is
appropriate. It is often the case that the variability increases as the true concentration increases.)
The variability (oc) of the measured concentration values (c) was modeled by the following
relationship,
where a, k, and P are constants to be estimated from the data. After determining the relationship
between the mean and variability, appropriate weighting was determined as the reciprocal of the
variance.
Yc = h(c) + error
(1)
o2c =a + kc^
(2)
weight = w c =
(3)
24
-------
The form of the linear regression model fitted was h(c) ao a,c. In the concentration sub-
region where the linear calibration model provides a valid representation of the concentration-
response relation, concentration values were calculated from the estimated calibration curve using
the relation
, , Y - a
c = h \Yc) = (4)
a j
A test for departure from linearity was carried out by comparing the residual mean square
1 6 ~
t£ (Yc - ao - aiC)2ncwc. (5)
4 ,-=i ' ' '
to an F-distribution with 6-2 = 4 numerator degrees of freedom.
Yci is the average of the nci analyzer responses at the ith calibration concentration, cr The
regression relation was fitted to the individual responses; however, only the deviation about the
sample mean analyzer responses at each calibration concentration provide information about
goodness-of-fit.
E E
,=i j=i
(Xc
C'J
-a,
~aic)2
w . =
E E
,=i j=i
(Y - Y )2 w + (7 -a„ -a,c)
v CI CI' CI Z—/ V CIJ 0 1 I'
nw
CI CI
i = l
The first summation on the right side of the equation provides information only about response
variability. The second summation provides all the information about goodness-of-fit to the
straight-line calibration model. This is the statistic that is used for the goodness-of-fit test.
5.1.2 Detection Limit
Limit of detection (LOD) is defined as the smallest true concentration at which an analyzer's
expected response exceeds the calibration curve at zero concentration by three times the standard
deviation of the analyzer's zero reading, i.e., a0 + 3 a0, if the linear relation is valid down to zero.
The LOD may then be determined by
LOD =
(a + 3o ) - a
^ O O' G
a,
3a
a,
(6)
where a0 is the estimated standard deviation at zero concentration. The LOD is estimated as
LOD = 3a0 / a0. The standard error of the estimated detection limit is approximately
25
-------
SE (LOD) * LOD
SEict^y
2(n-\)
a,
Note that the validity of the detection limit estimate and its standard error depends on the validity
of the assumption that the fitted linear calibration model accurately represents the response down
to zero concentration.
5.1.3 Response Time
The response time of the analyzers to a step change in analyte concentration was calculated by
determining the total change in response due to the step change in concentration, and then
determining the point in time when 95 percent of that change was achieved. Using data taken
every 10 seconds, the following calculation was carried out:
Total Response = Rc - Rz
where Rc is the final response of the analyzer to the calibration gas and Rz is the final response of
the analyzer to the zero gas. The analyzer response that indicates the response time then is:
Response950/o = 0.95(Total Response) + Rz.
The point in time at which this response occurs was determined by inspecting the response/time
data, linearly interpolating between two observed time points, as necessary. The response time
was calculated as:
RT = Time950/o - Time,,
where time950/o is the time at which ResponseRX occurred and Time; is the time at which the span
gas was substituted for the zero gas. Since only one measurement was made, the precision of the
response time was not determined.
5.1.4 Interrupted Sampling
The effect of interrupted sampling is the arithmetic difference between the zero data and between
the span data obtained before and after the test. Differences are stated as ppm. No estimate was
made of the precision of the observed differences.
5.1.5 Interferences
Interference is reported as both the absolute response (in ppm) to an interferant level, and as the
sensitivity of the analyzer to the interferant species, relative to its sensitivity to NO or N02. The
relative sensitivity is defined as the ratio of the observed N0/N02/N0x response of the analyzer to
26
-------
the actual concentration of the interferant. For example, an analyzer that measures NO is
challenged with 500 ppm of CO, resulting in an absolute difference in reading of 1 ppm (as NO).
The relative sensitivity of the analyzer is thus 1 ppm/500 ppm = 0.2 percent. The precision of the
interference results was not estimated from the data obtained, since only one measurement was
made for each interferant.
5.1.6 Pressure Sensitivity
At each of ambient pressure, reduced pressure (-10 inches of water), and increased pressure
(+10 inches of water), the analyzer flow rate, the response on zero gas, and the response on span
gas were measured for each analyzer. Variability in zero and span responses for reduced and
increased pressures was assumed to be the same as the variability at ambient pressure. The
variability determined in the linearity test was used for this analysis. The duct pressure effects on
analyzer flow rates and response were assessed by separate linear regression trend analyses for
flow rate and for response. The precision of the pressure effects on zero concentration response
and on span gas response was estimated based on the variability observed in the linearity test.
Statistical significance of the trends across duct pressures was determined by comparing the
estimated trends to their estimated standard errors, based on two-tailed t-tests:
t = pi (0.040825
-------
5.2 Combustion Source Tests
5.2.1 Accuracy
The relative accuracy (RA) of the analyzers with respect to the reference method is expressed as:
_ v
I ,71 ^ d
\d\ + fn-1
Jn (7)
RA = = s— x 100% v '
x
where d refers to the difference between the average of the two reference units and one of the
tested units and x corresponds to the average of the two reference unit values. Sd denotes the
sample standard deviation of the differences, based on n = 9 samples, while tan_i is the t value for
the 100(1 - a)th percentile of the distribution with n - 1 degrees of freedom. The relative accuracy
was determined for an a value of 0.025 (i.e., 97.5 percent confidence level, one-tailed). The RA
calculated in this way can be determined as an upper confidence bound for the relative bias of the
analyzer |<7|/x, where the bar indicates the average value of the differences or of the reference
values.
Assuming that the reference method variation is due only to the variation in the output source and
the true bias between the test and reference methods is close to zero, an approximate standard
error for RA is
SE *
S„
yfnx ^
0.3634 + \t
n-1
i
2(»-l)
X 100%
(8)
5.2.2 Zero/Span Drift
Statistical procedures for assessing zero and span drift were similar to those used to assess
interrupted sampling. Zero (span) drift was calculated as the arithmetic difference between zero
(span) values obtained before and after sampling of each combustion source. The same calculation
was also made using zero and span values obtained before and after the linearity and ambient
temperature tests. No estimate was made of the precision of the zero and span drift values.
5.2.3 Measurement Stability
The temporal stability of analyzer response in extended sampling from a combustion source was
assessed by means of a trend analysis on 60 minutes of data obtained continuously using the diesel
generator as the source. The existence of a difference in trend between the test unit and the
average of the reference units was assessed by fitting a linear regression line with the difference
between the measured concentration for a test unit and the average of the reference units as the
dependent variable, and time as the independent variable. Subtracting the average reference unit
values adjusts for variation in the source output. The slope and the standard error of the slope are
28
-------
reported. The null hypothesis that the slope of the trend line on the difference is zero was tested
using a one-sample two-tailed t-test with n - 2 = 58 degrees of freedom.
5.2.4 Inter- Unit Repeatability
The purpose of this comparison was to determine if any significant differences in performance
exist between two identical analyzers operating side by side. In tests in which analyzer perfor-
mance was verified by comparison with data from the reference method, the two identical units of
each type of analyzer were compared to one another using matched pairs t-test comparisons. In
tests in which no reference method data were obtained (e.g., linearity test), the two units of each
analyzer were compared using statistical tests of difference. For example, the slopes of the
calibration lines determined in the linearity test, and the detection limits determined from those
test data, were compared. Inter-unit repeatability was assessed for the linearity, detection limit,
accuracy, and measurement stability tests.
For the linearity test, the intercepts and slopes of the two units were compared to one another by
two-sample t-tests using the pooled standard error, with combined degrees of freedom the sum of
the individual degrees of freedom.
For the detection limit test, the detection limits of the two units were compared to one another by
two-sample t-tests using the pooled standard error with 10 degrees of freedom (the sum of the
individual degrees of freedom).
For the relative accuracy test, repeatability was assessed with a matched-pairs two-tailed t-test
with n - 1 = 8 degrees of freedom.
For the measurement stability test, the existence of differences in trends between the two units
was assessed by fitting a linear regression to the paired differences between the units. The null
hypothesis that the slope of the trend line on the paired differences is zero was tested using a
matched-pairs t-test with n - 2 = 58 degrees of freedom.
5.2.5 Data Completeness
Data completeness was calculated as the percentage of possible data recovered from an analyzer
in a test; the ratio of the actual to the possible number of data points, converted to a percentage,
i.e.,
Data Completeness = (Na)/(Np) x 100%,
where Na is the number of actual and Np the number of possible data points.
29
-------
Chapter 6
Statistical Results
6.1 Laboratory Tests
6.1.1 Linearity
Tables 6-la, b, c, and d list the data obtained in the linearity tests for NO and N02. Tables 6-la
and b list the results of the initial NO and N02 linearity tests, respectively. These tests were
performed over ranges of 0 to 4,000 ppm NO and 0 to 500 ppm N02 on January 17, 1999. Tables
6-lc and d list the corresponding results of the second linearity tests, performed over ranges of 0
to 1,000 ppm NO and 0 to 200 ppm N02 on February 19, 1999. The response of both the NO and
N02 sensors in each analyzer is shown in those tables.
Tables 6-2a and b show the results of the linear calibration curve fits for each unit and each
analyte, based on the data shown in Tables 6-la, b, c, and d. Table 6-2a shows the statistical
results obtained from a linear regression to all of the data points obtained in the first linearity test
(Tables 6-la and b). The results shown indicate substantial departure from linearity for both NO
and N02 with both analyzers. Table 6-2a indicates that all regression slopes are greater than 1.05,
well outside the range of 0.98 to 1.02 stated as acceptable in the SCAQMD test protocol.(8) In
addition, Table 6-2a indicates relatively high intercept values for NO, and R2 values for both NO
and N02 that are below the 0.999 value stated in the SCAQMD protocol.
In contrast, Table 6-2b shows good results from the second linearity test of the ECOM analyzers.
Intercepts are below 5 ppm for NO, and below 0.6 ppm for N02, on both analyzers, and the
slopes range from 0.994 to 1.011. All the slopes are well within the acceptable range of 0.98 to
1.02. The R2 values in Table 6-2b also all exceed 0.9995.
The results in Tables 6-2a and b give conflicting views of the linearity of the ECOM analyzers.
The main difference between these two sets of results is the concentration range over which the
analyzers were tested. Table 6-2a reports results from testing over 0 to 4,000 ppm NO and 0 to
500 ppm N02, whereas Table 6-2b reports results from testing over 0 to 1,000 ppm NO and 0 to
200 ppm N02. Investigation of the data has shown that the difference in these two sets of results
has to do with these concentration ranges and with the actual linear range of the ECOM
analyzers, as discussed below.
30
-------
Table 6-la. Data from NO Linearity Test over 0-4,000 ppm Range for ECOM A-PLUS
Analyzers
Actual NO
Unit A NO
Unit A N02
Unit B NO
Unit B N02
Reading
(ppm)
(ppm)
(ppm)
(ppm)
(ppm)
1
0.0
5
7
5
8
2
3925.0
3911
24
3906
30
3
397.5
469
13
520
10
4
1499.7
1665
14
1913
16
5
0.0
9
5
8
6
6
2600.7
2849
NR
3271
NR
7
747.3
869
11
978
13
8
397.5
468
9
521
10
9
0.0
10
7
9
7
10
747.3
847
7
965
8
11
1499.7
1668
9
1913
11
12
2601.3
2846
12
3269
14
13
0.0
12
7
11
8
14
3925.0
3912
12
3905
14
15
2601.3
2881
14
3290
15
16
1499.7
1706
12
1936
13
17
0.0
18
8
17
9
18
747.3
854
8
968
9
19
397.5
459
8
512
7
20
3925.0
3911
11
3906
12
21
0.0
16
7
19
8
NR: Not recorded.
31
-------
Table 6-lb. Data from N02 Linearity Test over 0-500 ppm Range for ECOM A-PLUS
Analyzers
Number
Actual N02
(ppm)
Unit A NO
(ppm)
Unit A N02
(ppm)
Unit B NO
(ppm)
Unit B N02
(ppm)
1
0.0
0
0
0
0
2
493.2
20
505
14
505
3
49.8
5
61
5
62
4
179.9
9
199
8
199
5
0.0
4
3
3
3
6
350.3
NR
375
NR
374
7
89.7
7
108
7
108
8
49.7
6
62
6
62
9
0.0
4
4
4
5
10
89.7
6
102
6
102
11
179.9
10
199
8
198
12
350.3
17
376
15
376
13
0.0
4
4
4
3
14
493.2
25
522
16
524
15
350.3
19
386
13
388
16
179.9
11
209
9
210
17
0.0
5
7
5
9
18
89.6
7
104
6
104
19
49.7
6
61
6
61
20
493.2
22
519
18
521
21
0.0
5
9
5
11
NR: Not recorded.
32
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Table 6-lc. Data from NO Linearity Test over 0 - 1,000 ppm Range for ECOM Analyzers
Number
Actual N02
(ppm)
Unit A NO
(ppm)
Unit A N02
(ppm)
Unit B NO
(ppm)
Unit B N02
(ppm)
1
0
0
0
0
0
2
997.8
1001
3
1000
3
3
96.6
108
1
106
0
4
400.2
417
1
416
1
5
0
4
0
3
0
6
700.5
718
1
718
1
7
200
214
0
212
0
8
100
109
0
107
0
9
0
4
0
3
0
10
200
209
0
209
0
11
400.2
416
0
415
0
12
700.6
718
1
718
0
13
0
3
0
3
0
14
997.8
1000
1
1001
1
15
700.5
718
1
718
1
16
400.2
422
0
419
0
17
0
4
0
3
0
18
200
210
0
209
0
19
100
109
0
107
0
20
997.8
1000
1
1001
1
21
0
3
0
2
0
33
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Table 6-ld. Data from N02 Linearity Test Over 0-200 ppm Range for ECOM Analyzers
Number
Actual N02 Unit A NO
(ppm) (ppm)
Unit A N02
(ppm)
Unit B NO
(ppm)
Unit B NO,
(ppm)
1
0
0
0
0
0
2
200
7
200
7
200
3
19.7
3
19
3
19
4
79.6
4
79
4
79
5
0
3
1
2
1
6
139.8
6
139
5
139
7
39.7
4
40
3
40
8
19.7
4
20
3
19
9
0
3
1
3
1
10
39.7
4
39
3
39
11
79.7
4
79
4
79
12
139.8
6
140
5
140
13
0
3
1
3
1
14
200
7
199
6
199
15
139.8
7
141
6
141
16
79.7
5
81
4
81
17
0
4
1
3
1
18
39.7
4
39
3
39
19
19.7
4
19
3
19
20
200
8
200
7
199
21
0
4
1
3
1
Table 6-2a. Statistical Results for First Linearity Test with ECOM Analyzers (1/17/99)
Unit A
Unit B
Linear Regression
NO
no2
NO
no2
Intercept (ppm) (Std
Err)
Slope (Std Err)
R2
20.514 (7.161)
1.080 (0.014)
0.997
6.600 (1.308)
1.054 (0.009)
0.9986
53.186 (33.002)
1.137 (0.035)
0.9828
7.336 (1.447)
1.053 (0.010)
0.9984
34
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Table 6-2b. Statistical Results for Second Linearity Test on ECOM Analyzers (2/18/99)
Unit A
Unit B
Linear Regression
NO
no2
NO
no2
Intercept (ppm) (Std
4.841(1.182)
0.566 (0.182)
4.326(1.191)
0.585 (0.185)
Err)
Slope (Std Err)
1.011 (0.004)
0.995 (0.003)
1.011 (0.004)
0.994 (0.003)
R2
0.9997
0.9999
0.9997
0.9999
The results shown in Table 6-2a are from linearity testing over the nominal full-scale ranges of the
ECOM analyzers (i.e., the ranges stated in vendor literature). Those tests were conducted by first
calibrating the analyzers with NO or N02 span gas at concentrations near the nominal full-scale
range values. Subsequent data points were then obtained without further adjustment of the
analyzers. Inspection of the test data has shown that the results in Table 6-2a are not due to a
non-linearity of analyzer response, but rather to a limitation in the extent of the linear range. This
is illustrated in Figure 6-1, which shows the linearity test data for the Unit B NO response, taken
directly from Table 6-la. That figure shows that the analyzer response at the full-scale data point
(3,925 ppm NO actual concentration) agrees well with the actual value, but for all lower data
points, the analyzer response is too high. However, except for the full-scale data point, all the
analyzer response data appear to be highly linear. The conclusion drawn from Figure 6-1 is that
the linear range of the Unit B NO sensor is not 4,000 ppm, as stated, but approximately 3,000
ppm. The analyzer's response to NO levels above 3,000 ppm flattens out, or saturates. The slopes
shown in Table 6-2a are an artifact of this saturation effect, since calibrating with an artificially
low response near full scale makes response at all lower concentrations appear erroneously high.
Based on those slopes, the effect seems to be larger for the NO sensors than for the N02 sensors.
Figures similar to Figure 6-1 indicate that the linear ranges of the Unit A NO and N02 sensors are
actually about 0 to 3,500 ppm and 0 to 450 ppm, respectively. The linear ranges of the Unit B NO
and N02 sensors are about 0 to 3,000 ppm and 0 to 450 ppm, respectively.
For the purpose of estimating detection limits (see Section 6.1.2), both sets of linearity test data
were used. However, before estimating detection limits, the data from the highest concentration
point in the first linearity test (Tables 6-1 a and b) were omitted, and the regression was
recalculated using the remaining points, to avoid biasing the intercept due to the effect shown in
Figure 6-1. In addition, consistently increasing responses on zero gas were observed in the first
linearity tests (Tables 6-la and b). This behavior is apparently due to a "memory" effect, in which
the analyzers do not fully return to baseline after exposure to elevated NO or N02 levels. This
behavior is a transient response, which can be minimized by sufficiently long refresh cycles
between measurements.(10) However, this behavior might be important in real sampling, as in
measuring widely different NOx levels upstream and downstream of a selective catalytic reactor
(SCR) for NOx removal. If a single calibration covering the entire range of concentrations to be
encountered were prepared, measurements at the low concentrations (i.e., downstream of the
SCR) might be compromised. In that instance it would be preferable to conduct a low-level
calibration and low-level measurements (downstream), followed by a high-level calibration and
upstream measurements. Alternatively, dilution of the high-level stream, or use of two separate
analyzers for the low and high concentration regimes, would be preferable.
35
-------
Actual NO, ppm
Figure 6-1. Results of First NO Linearity Test on ECOM Unit B
-------
The linearity test data in Tables 6-la through d also indicate the extent of cross-sensitivity of the
ECOM NO and N02 sensors. Using the results from the second linearity test (Table 6-lc), linear
regression of the N02 responses of the analyzers against the NO levels provided gives the
following regression equations:
Unit A N02 Response = 0.00159 (Actual NO) - 0.07 ppm
Unit B N02 Response = 0.00154 (Actual NO) - 0.15 ppm
with R2 values of 0.59 and 0.87, respectively. These results indicate a very slight sensitivity of the
N02 sensors to NO, amounting to about 0.15 percent of the actual NO level. This degree of
cross-sensitivity is negligible in any real-world application.
The corresponding linear regression of NO response to N02 levels provided in Table 6-ld gives
the following equations:
Unit A NO Response = 0.0224 (Actual N02) + 2.9 ppm
Unit B NO Response = 0.0214 (Actual N02) + 2.3 ppm
with R2 values of 0.78 and 0.84, respectively. These results indicate that the ECOM NO sensors
have a cross-sensitivity to N02 that amounts to about 2 percent of the actual N02 level. This
interference is likely to be significant only in a source where N02 levels equal or exceed NO
levels.
6.1.2 Detection Limit
Tables 6-3a and b show the estimated detection limits for each test unit and each analyte,
determined from the data obtained in the linearity tests.
Table 6-3a. Estimated Detection Limits From First Linearity Test (1/17/99) for the ECOM
Analyzers
Unit A
Unit B
NO
no2
NO
no2
Estimated Detection Limit (ppm)
12.834
8.957
12.896
11.738
(Standard Error) (ppm)
(4.061)
(2.834)
(4.078)
(3.713)
Table 6-3b. Estimated Detection Limits From Second Linearity Test 2 (2/18/99) for the
ECOM Analyzers
Unit A
Unit B
NO
no2
NO
no2
Estimated Detection Limit (ppm)
4.595
1.231
3.593
1.232
(Standard Error) (ppm)
(1.453)
(0.389)
(1.136)
(0.390)
37
-------
Table 6-3a shows the detection limits calculated based on the data from the first linearity tests of
the ECOM analyzers (Tables 6-1 and b), excluding the highest concentration points. Detection
limits of about 13 ppm for NO are indicated for both analyzers. Detection limits of about 9 ppm
and 12 ppm for N02 are indicated for Unit A and Unit B, respectively. These detection limits
result in part from elevation of the zero readings of the ECOM analyzers due to the high NO and
N02 levels used in the first linearity tests. For example, Table 6-la indicates that the NO readings
of the two ECOM analyzers on zero gas increased from 5 ppm to 16 and 19 ppm, respectively,
over the course of the NO linearity test. Similarly, Table 6-lb shows that the N02 readings of the
two analyzers on zero gas increased from zero to 9 and 11 ppm, respectively, over the course of
the N02 linearity test. These observations indicate a memory effect, in that the analyzers did not
return to their previous zero reading after exposure to elevated NO or N02 levels, and the zero
readings continued to increase with continued exposure through the test. Thus, the detection
limits shown in Table 6-3a are biased upward by this effect, but indicate the behavior that may be
expected when the analyzers are calibrated over their full-scale ranges.
Table 6-3b shows the detection limits determined from the second set of linearity tests (Tables 6-
lc and d). NO detection limits are about 5 ppm and 4 ppm for Unit A and Unit B, respectively,
and N02 detection limits are 1.2 ppm for both units. The data from the second linearity tests
clearly show more stable zero readings as the tests progressed than those observed in the first
tests at higher concentrations, indicating that the differences in zero readings are related directly
to the exposure to high concentrations. The detection limits shown in Table 6-3b are more
representative of those achievable in actual source monitoring, since exposure to NO and N02 at
levels approaching the maximum full-scale range of the analyzer is not likely to occur. In fact, the
relative accuracy obtained with low-NOx sources (Section 6.2.1) suggests detection limits for
both NO and N02 that are comparable to the 1 ppm measurement resolution of the ECOM
analyzers.
6.1.3 Response Time
Table 6-4 lists the data recorded by the operator in the response time test of the ECOM A-PLUS
analyzers. It is clear from the first line of entries in Table 6-4 that data recording started after the
onset of the step change had been missed, and consequently only lower limits to the response
times can be determined. Table 6-5 shows the lower limit response times estimated from the data
in Table 6-4. For N02, lower limit response times of about 100 seconds are estimated. For NO,
the lower limit response times are quite different, 37 seconds for Unit A and 11 seconds for Unit
B. This difference is likely a result of the incomplete data recorded and consequent estimation of
the response times. However, the data do indicate that the ECOM analyzers respond more rapidly
to NO than to N02, and discussion with the vendor indicates that the results in Table 6-5 are
typical of the response times of the A-PLUS analyzers.
38
-------
Table 6-4. Response Time Data for ECOM A-PLUS Analyzers
Time (sec)
Unit A NO
(ppm)
Unit A N02
(ppm)
Unit B NO
(ppm)
Unit B N02
(ppm)
0
1455
118
1503
119
10
2606
251
3170
261
20
2734
295
3229
302
30
2761
331
3234
327
40
2780
339
3239
343
50
2791
346
3244
347
60
2798
351
3246
352
70
2802
355
3248
354
80
2806
358
3250
356
90
2810
360
3251
359
100
2813
361
3252
360
110
2816
362
3253
361
120
2818
364
3254
362
130
2819
365
3255
363
140
2822
366
3256
364
150
2823
367
3257
365
160
2826
368
3258
366
170
2828
369
3258
366
180
2828
370
3259
367
190
2830
370
3260
368
200
2832
370
3261
369
210
2833
371
3261
369
220
2834
371
3262
370
230
2835
371
3262
370
240
2837
372
3263
371
250
2838
372
3264
371
260
2839
373
3265
371
270
2840
373
3266
372
280
2841
373
3266
372
290
2842
374
3267
373
300
2843
374
3267
373
Table 6-5. Lower Limits of Response Times Estimated for ECOM A-PLUS Analyzers
Unit A
Unit B
NO
no2
NO
no2
Response Time* (sec)
37
102
11
103
* The analyzer's responses were recorded at 10-second intervals; therefore the point in time when the
95 percent response was achieved was determined by interpolating between recorded times to the nearest
second.
39
-------
6.1.4 Interrupted Sampling
Table 6-6 shows the zero and span data resulting from the interrupted sampling test, and
Table 6-7 shows the differences (pre- minus post-) of the zero and span values. Span concen-
trations of 3,925 ppm NO and 493.2 ppm N02 were used for this test. As noted above, the pre-
shutdown NO and N02 zero readings were apparently elevated due to prolonged exposure to high
levels in the linearity test. This elevation of zero levels was no longer present after the overnight
shutdown. That is, all zero readings dropped to zero as a result of the shutdown period. Units A
and B performed similarly in terms of both zero and span response for both NO and N02. The
changes in NO span response due to the shutdown are equivalent to less than 0.5 percent of the
3,925 ppm NO span value, and to 1.6 to 1.8 percent of the 493.2 ppm N02 span value.
Table 6-6. Data from Interrupted Sampling Test with ECOM A-PLUS Analyzers
Unit A NO
Unit A NO
2 Unit B NO
Unit B N02
Pre-Shutdown Date:
1/17/99
Time:
17:40
Pre-Shutdown Zero (ppm):
12
6
11
6
Pre-Shutdown Span (ppm):
3911
516
3906
511
Post-Shutdown Date:
1/18/99
Time:
09:15
Post-Shutdown Zero (ppm):
0
0
0
0
Post-Shutdown Span (ppm):
3928
507
3915
503
Table 6-7. Pre- to Post-Test Differences as a Result of Interruption of Operation of ECOM
A-PLUS Analyzers
Unit A
Unit B
Pre-Shutdown—Post-Shutdown
NO
no2
NO N02
Zero Difference (ppm)
12
6
11 6
Span Difference (ppm)
-17
9
-9 8
6.1.5 Interferences
Table 6-8 lists the data obtained in the interference tests. Table 6-9 summarizes the sensitivity of
the analyzers to interferant species, based on the data from Table 6-8. Note that cross-sensitivity
to NO and N02 has been addressed using the linearity data, in Section 6.1.1.
40
-------
Table 6-8. Data from Interference Tests on ECOM A-PLUS Analyzers
Interferant
Interferant, Cone.
Response (ppm)
Gas
(ppm)
Unit A NO
Unit A NO,
Unit B NO
Unit B NO,
Zero
3
1
2
1
CO
496 ppm
2
1
3
2
Zero
4
1
3
1
o
o
N)
5.03%
2
1
2
1
Zero
3
1
3
1
nh3
494 ppm
3
0
2
0
Zero
3
0
2
0
HCs
590 ppm
3
0
2
0
Zero
2
0
2
0
S02
501 ppm
3
0
3
0
Zero
2
0
2
1
SO, + NO
451+388 ppm
480
1
540
1
Table 6-9. Results of Interference Tests of ECOM A-PLUS Analyzers
Unit A Response ppm Unit B Response ppm
(relative sensitivity, %) (relative sensitivity, %)
Interferent NO N02 NO N02
CO (496 ppm)
-1 (-0.2%)
0
1 (0.2%)
1 (0.2%)
C02 (5.03%)
-2 (<0.01%)
0
-1 (<0.01%)
0
NH3 (494 ppm)
0
-1 (-0.2%)
-1 (0.2%)
-1 (-0.2%)
HCs (590 ppm)
0
0
0
0
S02 (501 ppm)
1 (0.2%)
0
1 (0.2%)
0
S02 (451 ppm) +
478
1
538
0
NO (388 ppm)*
(20.0%)*
(0.2%)*
(33.3%)*
*See text.
Table 6-9 indicates that none of the five individual interferants has a significant effect on the NO
or N02 sensors of the ECOM analyzers. The maximum difference in reading relative to the zero
readings was 2 ppm, and no individual interferant had an apparent relative sensitivity exceeding
0.2 percent of that for NO or N02.
The mixture of S02 and N02 produced NO readings on Units A and B of 478 ppm and 538 ppm,
respectively, after correction for zero gas readings (Table 6-9). If the excess signal above the
true NO value of 388 ppm were due to an effect of the S02 present, then the effect of the S02
would be equivalent to a 20 percent relative sensitivity for Unit A (i.e., (478 - 388)/451 xlOO =
41
-------
20.0). The corresponding calculation for Unit B gives a 33.3 percent relative sensitivity.
However, the elevated response to the S02/N0 mixture is more likely related to the "non-
linearity" found in the initial linearity tests, discussed in Section 6.1.1. As Table 6-la shows,
when sampling an NO concentration of 397.5 ppm in the first linearity test, Unit A gave
readings of 459 to 469 ppm, and Unit B indicated 512 to 521 ppm. This effect has been traced to
the actual linear range of the analyzers, as described in Section 6.1.1. Since the interference test
described here was done before the findings of Section 6.1.1 were known, and without
adjustment or calibration after the linearity test, it is likely that most if not all of the excess NO
response shown in Table 6-9 is an artifact of the linear range effect. No interference effect of
S02 in the presence of NO can be inferred from the results in Table 6-9.
6.1.6 Pressure Sensitivity
Table 6-10 lists the data obtained in the pressure sensitivity test. Table 6-11 summarizes the
findings from those data in terms of the ppm differences in zero and span readings at the different
duct gas pressures, and the ccm differences in analyzer flow rates at the different duct gas
pressures. No significant effect of duct pressure was seen with either ECOM A-PLUS analyzer.
Zero readings changed with pressure by 1 ppm or less for both NO and N02 on both analyzers.
Span readings for N02 changed by 4 ppm or less, equivalent to about 1 percent or less of the
350 ppm N02 span concentration. Span readings for NO changed by 40 ppm or less, equivalent to
about 1.5 percent or less of the 2,600 ppm NO span concentration.
Tables 6-10 and 6-11 also indicate that the sample gas flow rate drawn by the two analyzers is
only slightly dependent on the duct pressure. Sample flow rates at +10 inches of water exceeded
those at ambient pressure by 0.7 to 1.9 percent; flow rates at -10 inches of water were reduced by
3.1 to 4.3 percent. As noted above, no significant zero or span changes were associated with
these small flow differences.
6.1.7 Ambient Temperature
Table 6-12 lists the data obtained in the ambient temperature test with the ECOM A-PLUS
analyzers.
Table 6-13 summarizes the sensitivity of the analyzers to changes in ambient temperature. This
table is based on the data shown in Table 6-12, where the span values are 700 ppm for NO and
140 ppm for N02.
Table 6-13 indicates that no significant effect of ambient temperature was found with the ECOM
analyzers, with the exception of the NO span readings on Unit B. Zero differences over the course
of this test were 1.5 ppm or less for both NO and N02 on both analyzers. The span differences
observed for NO and N02 are larger (relative to room temperature results) for the reduced
temperature test (i.e., -9 to -21.5 ppm) than for the elevated temperature test (i.e., 0 to 8.5 ppm).
For N02 the span differences are equivalent at most to 7.5 percent of the 140 ppm span
concentration. For NO the span differences are equivalent to 0.6 to 3.1 percent of the 700 ppm
span concentration, with only the value for Unit B being statistically significant.
42
-------
Table 6-10. Data from Pressure Sensitivity Test for ECOM A-PLUS Analyzers
Pressure Unit A NO Unit A N02 Unit B NO Unit B N02
Ambient
+10 in. H20
-10 in. H20
Flow rate (ccm)
2280
2280
2175
2175
Zero (ppm)
0
0
0
0
NO span (ppm)
2975
2
3410
1
Zero (ppm)
0
0
0
0
N02 span (ppm)
14
378
14
371
Zero (ppm)
2
1
2
1
Flow rate (ccm)
2323
2323
2190
2190
Zero (ppm)
1
0
1
0
NO span (ppm)
2990
1
3431
1
Zero (ppm)
1
0
1
0
N02 span (ppm)
14
382
15
374
Zero (ppm)
1
1
1
0
Flow rate (ccm)
2209
2209
2082
2082
Zero (ppm)
1
0
2
0
NO span (ppm)
3008
1
3450
1
Zero (ppm)
1
0
1
0
N02 span (ppm)
16
377
11
370
Zero (ppm)
1
1
2
1
Table 6-11. Pressure Sensitivity Results for ECOM A-PLUS Analyzers
Unit A
NO
no2
NO
Unit B
no2
Zero
High-Ambient (ppm cliff*)
0.33
0
0.33
-0.33
Low-Ambient (ppm diff)
0.33
0
1
0
Significant Pressure Effect
N
N
N
N
Span
High-Ambient (ppm diff)
15
4
21
3
Low-Ambient (ppm diff)
33
-1
40
-1
Significant Pressure Effect
N
N
N
N
Flow
High-Ambient (ccm diff*)
43
15
Rate
Low-Ambient (ccm diff)
-71
-93
* ppm or ccm difference between high/low and ambient pressures. The differences were calculated based on the
average of the zero check responses.
43
-------
Table 6-12. Data from Ambient Temperature Test of ECOM A-PLUS Analyzers
Unit A NO Unit A NO, Unit B NO Unit B NO,
Condition (PPm) (PPm) (PPm) (PPm)
(Room Temp.)
Temp. 24.4°C (76°F)
Zero 2 0 2 0
NO span 716 0 717 0
Zero 2 0 10
N02 span 5 137 4 137
(Heated)
Temp. 40°C (104°F)
Zero 10 2 0
NO span 719 3 720 3
Zero 4 0 3 0
N02 span 6 135 6 135
(Cooled)
Temp. 8.9°C (48°F)
Zero 0 0 0 0
NO span 704 2 690 2
Zero 0 10 1
N02 span 0 126 0 124
(Room Temp.)
Temp. 24.4°C (76°F)
Zero 10 0 0
NO span 713 3 706 3
Zero 1111
NO, span 3 133 3 132
Table 6-13. Ambient Temperature Effects on ECOM A-PLUS Analyzers
Unit A Unit B
NO
no2
NO
no2
Zero
Heat - room (ppm diff*)
1
-0.25
1.5
-0.25
Cool - room (ppm diff)
-1.5
0.25
-1
0.25
Significant Temp Effect
N
N
N
N
Span
Heat - room (ppm diff)
4.5
0
8.5
0.5
Cool - room (ppm diff)
-10.5
-9
-21.5
-10.5
Significant Temp Effect
N
N
Y
N
* ppm difference between heated/cooled and room temperatures. The differences were calculated from the
average of the recorded responses at room temperature.
44
-------
6.1.8 Zero and Span Drift
Zero and span drift was evaluated from data taken at the start and end of the linearity and ambient
temperature tests. Those data are shown in Table 6-14, and the drift values observed are shown as
pre- minus post-test differences in ppm in Table 6-15. Table 6-15 is of interest because it provides
zero and span drift information from three different sets of span concentrations. Zero drift for
both NO and N02 on both ECOM units was greatest in the first linearity test, in which the highest
span concentrations were used. The cause of this drift is discussed in Section 6.1.1. In the other
two tests listed in Table 6-15, zero drift never exceeded 3 ppm on either analyzer. Span drift also
was greatest as a result of the first linearity test. Span values for NO decreased over the course of
that test (i.e., pre- minus post-test differences in Table 6-15 are positive), by amounts equal to less
than 0.5 percent of the 3,925 ppm span value. N02 span values increased over the course of the
first linearity test (differences in Table 6-15 are negative) by amounts equal to 3.6 to 4.6 percent
of the 493.2 ppm span concentration. Span differences in the second linearity test were 2 ppm or
less (less than 1 percent relative to span). In the ambient temperature test, span drift for N02 was
equivalent to about 3 to 4 percent of the 140 ppm span concentration and 0.4 to 1.6 percent of
the 700 ppm NO span concentration.
Table 6-14. Data from Linearity and Ambient Temperature Tests Used to Assess Zero and
Span Drift of the ECOM A-PLUS Analyzers.
Unit A NO
Unit A N02
Unit B NO
Unit B N02
Test
(ppm)
(ppm)
(ppm)
(ppm)
First Linearity*
Pre-Test Zero
0
0
0
0
Pre-Test Span
3925
493.2
3925
493.2
Post-Test Zero
12
6
11
6
Post-Test Span
3911
516
3906
511
Second Linearity* *
Pre-Test Zero
0
0
0
0
Pre-Test Span
1000
200
1000
201
Post-Test Zero
3
0
2
0
Post-Test Span
1000
200
1001
199
Ambient Temperature***
Pre-Test Zero
2
0
2
0
Pre-Test Span
716
137
717
137
Post-Test Zero
1
1
0
1
Post-Test Span
713
133
706
132
*NO 0 - 4,000 ppm and N02 0 - 500 ppm.
**NO 0 - 1,000 ppm and N02 0 - 200 ppm.
***Span values were 700 ppm NO and 140 ppm N02.
45
-------
Table 6-15. Zero and Span Drift Results for the ECOM A-PLUS Analyzers
Unit A
Unit B
NO
no2
NO
no2
Pre- and Post-Differences
(ppm)
(ppm)
(ppm)
(ppm)
First Linearity Test
Zero
-12
-6
-11
-6
Span
14
-22.8
19
-17.8
Second Linearity Test
Zero
-3
0
-2
0
Span
0
0
-1
2
Ambient Temperature Test
Zero
0
-1
2
-1
Span
3
4
11
5
6.2 Combustion Source Tests
6.2.1 Relative Accuracy
Tables 6-16a through d list the measured NO, N02, and NOx data obtained in sampling of the four
combustion sources. Note that the ECOM analyzers measure NO and N02, and the indicated NOx
totals are the sum of those data; in contrast, the reference monitors measure NO and NOx, and
N02 is determined by difference. Tables 6-16a through d show that a wide range of NO and N02
concentrations was emitted by the four sources.
Table 6-17 displays the relative accuracy (in percent) for NO, N02, and NOx of Units A and B for
each of the four sources. Estimated standard errors are shown with the relative accuracy
estimates. These standard error estimates were calculated under the assumption of zero true bias
between the reference and test methods. If the bias is in fact non-zero the standard errors
underestimate the variability.
Table 6-17 shows that for nearly all source sampling, the ECOM A-PLUS analyzers exhibited
relative accuracy of 1.3 to 15 percent for NO, N02, and NOx. For all sources tested, the NOx
relative accuracy was 12.1 percent or better. The only exceptions were those conditions in which
NO and/or N02 were present at levels of 6 ppm or less. For NO from the rangetop, relative
accuracy of about 20 percent was found on Unit B. For N02 from the rangetop, relative accuracy
values of about 50 percent were found with both analyzers. This relative accuracy at the low
levels observed from this source implies that the ECOM and reference results agree within about
1 ppm at these low levels, or within the measurement resolution of the ECOM analyzers (the
ECOM analyzers report data in whole ppm units only). Relative accuracy of 50 to 70 percent for
N02 was observed on the gas water heater (Table 6-17). Although the 1 ppm resolution of the
ECOM analyzers certainly contributes to these relative accuracy values, inspection of Table 6-16b
shows that variability in the N02 data from the two reference analyzers also contributes.
Determination of N02 by difference using the chemiluminescence method is especially subject to
error at high N0/N02 ratios, as in the water heater emissions.
46
-------
Table 6-16a. Data from Gas Rangetop in Verification of ECOM Analyzers
ECOM Analyzer Data
Reference Analyzer Data
Unit A NO
Unit A N02
Unit A NOx
Unit B NO
Unit B N02
Unit B NOx
14ANO
14A N02
14A NOs
10 NO
10 no2
10 NOx
(ppm)
(ppm)
(ppm)
(ppm)
(ppm)
(ppm)
(ppm)
(ppm)
(ppm)
(ppm)
(ppm)
(ppm)
1
5
1
6
5
1
6
4.1
1.9
6.1
5.2
1.9
7.1
2
5
1
6
6
1
7
4.8
1.6
6.4
5.7
1.6
7.3
3
6
1
7
6
1
7
4.9
1.8
6.7
5.6
1.8
7.4
4
6
1
7
6
1
7
5.1
1.6
6.7
5.9
1.9
7.8
5
6
1
7
6
1
7
5.1
1.8
6.8
6.0
1.8
7.8
6
6
1
7
7
1
8
5.3
1.6
6.9
6.0
1.9
7.9
7
6
1
7
7
1
8
5.3
2.0
7.3
6.0
2.3
8.2
8
7
1
8
7
1
8
5.5
1.9
7.4
6.4
1.8
8.2
9
7
1
8
7
1
8
5.4
2.0
7.4
6.5
1.8
8.3
Table 6-16b. Data from Gas Water Heater in Verification of ECOM Analyzers
ECOM Analyzer Data
Reference Analyzer Data
Unit A NO
Unit A N02
Unit A NOx
Unit B NO
Unit B N02
Unit B NOx
14ANO
14A NO,
14A NOs
10 NO
10 no2
10 NOx
(ppm)
(ppm)
(ppm)
(ppm)
(ppm)
(ppm)
(ppm)
(ppm)
(ppm)
(ppm)
(ppm)
(ppm)
1
72
4
76
73
4
77
69.6
8.5
78.1
66.9
4.6
71.5
2
64
3
67
66
3
69
59.8
3.0
62.8
58.3
1.7
60.0
3
63
3
66
65
2
67
57.4
3.9
61.3
56.2
2.6
58.8
4
64
3
67
66
3
69
58.2
3.7
61.9
56.5
3.9
60.4
5
64
3
67
66
2
68
59.0
3.8
62.8
57.4
2.9
60.3
6
64
3
67
65
2
67
59.1
2.8
62.0
57.1
2.1
59.2
7
65
3
68
66
2
68
53.1
9.7
62.8
56.4
3.7
60.1
8
63
3
66
64
2
66
58.5
1.2
59.7
56.9
1.6
58.4
9
61
3
64
62
2
64
54.5
5.6
60.1
55.0
3.9
58.9
-------
Table 6-16c. Data from Diesel Generator at High RPM in Verification of ECOM Analyzers
ECOM Analyzer Data
Reference Analyzer Data
Unit A NO
Unit A N02
Unit A NOx
Unit B NO
Unit B N02
Unit B NOx
14ANO
14A N02
14A NOs
10 NO
10 no2
10 NOx
(ppm)
(ppm)
(ppm)
(ppm)
(ppm)
(ppm)
(ppm)
(ppm)
(ppm)
(ppm)
(ppm)
(ppm)
1
118
73
191
117
69
186
115.8
71.2
187.0
113.2
75.5
188.7
2
112
69
181
109
66
175
106.0
68.9
174.9
109.2
62.8
172.0
3
109
67
176
108
64
172
108.0
60.5
168.5
111.2
66.0
177.2
4
110
65
175
108
62
170
102.1
62.6
164.6
106.3
69.1
175.4
5
110
65
175
109
63
172
106.0
58.4
164.4
111.2
66.0
177.2
6
110
64
174
108
62
170
102.1
60.5
162.5
106.3
70.2
176.4
7
109
65
174
107
63
170
101.1
62.6
163.6
106.3
70.2
176.4
8
110
65
175
109
63
172
102.1
63.6
165.7
107.2
71.3
178.5
9
115
65
180
114
62
176
107.0
56.3
163.3
114.2
61.8
176.0
00
Table 6-16d. Data from Diesel Generator at Idle in Verification of ECOM Analyzers
Unit A NO
(ppm)
Unit A N02
(ppm)
ECOM Analyzer Data
Unit A NOx Unit B NO
(ppm) (ppm)
Unit B N02
(ppm)
Unit B NOx
(ppm)
14ANO
(ppm)
14A NO,
(ppm)
Reference Analyzer Data
14A NOs 10 NO
(ppm) (ppm)
10 no2
(ppm)
10 NOx
(ppm)
1
328
137
465
326
135
461
326.6
131.9
458.5
325.7
130.2
455.9
2
332
135
467
332
134
466
330.5
134.0
464.6
326.7
134.4
461.1
3
335
136
471
332
135
467
331.5
135.1
466.6
329.7
135.5
465.2
4
335
135
470
333
134
467
332.5
132.0
464.5
330.7
131.3
461.9
5
335
135
470
335
133
468
330.5
129.8
460.4
326.7
131.2
457.9
6
332
137
469
329
135
464
325.6
135.0
460.6
322.7
133.3
456.1
7
332
138
470
330
136
466
332.5
126.7
459.2
324.7
130.2
454.9
8
336
141
477
333
139
472
331.5
136.1
467.7
328.7
132.3
461.0
9
303
157
460
299
154
453
302.1
151.5
453.6
289.0
142.8
431.7
-------
Table 6-17. Relative Accuracy of ECOM A-PLUS Analyzers
Unit A
Unit B
NO
no2
NOx
NO
no2
NOx
Source
(%)
(%)
(%)
(%)
(%)
(%)
Gas Rangetop
14.95*
51.50
8.57
20.63
51.50
3.73
(5.5 ppm NO, 2 ppm N02)***
(2.04)**
(2.06)
(1.45)
(1.90)
(2.06)
(1.34)
Gas Water Heater
12.81
52.60
10.78
15.31
70.72
12.09
(60 ppm NO, 4 ppm N02)
(0.84)
(12.15)
(0.77)
(0.85)
(12.43)
(0.79)
Diesel Generator-High RPM
5.24
5.00
3.97
3.62
5.77
1.47
(105 ppm NO, 65 ppm N02)
(0.57)
(1.24)
(0.40)
(0.51)
(1.18)
(0.38)
Diesel Generator-Idle
2.00
5.62
2.85
1.33
4.00
1.82
(325 ppm NO, 135 ppm N02)
(0.18)
(0.70)
(0.26)
(0.17)
(0.60)
(0.19)
*Relative accuracy calculated using equation 7.
**Standard error of relative accuracy value, estimated using equation 8.
***Approximate NO and N02 levels from each source are shown; see Tables 6-16a through d.
In addition to exhibiting good relative accuracy even at low analyte levels, the ECOM A-PLUS
analyzers exhibited excellent unit-to-unit precision in source emission measurements. In all
combustion tests, the two ECOM analyzers actually showed better unit-to-unit agreement than
did the two reference analyzers. For example, the differences between the average NOx values
obtained by ECOM Unit A and Unit B on the four combustion sources ranged from 0.8 to
4.2 percent, relative to the mean NOx values. This result indicates a high degree of consistency in
the performance of the ECOM analyzers on combustion sources.
6.2.2 Zero and Span Drift
Table 6-18 shows all the data used to evaluate zero and span drift of the ECOM A-PLUS
analyzers from the combustion source tests.
Table 6-19 summarizes the zero and span drift results, and shows that zero and span drift for both
NO and N02 with both analyzers was within ± 1 ppm in sampling of the two gas combustion
sources. Zero and span drift increased in progressing to the diesel source, indicating that exposure
to higher NOx levels increases both types of drift. With the diesel source, zero and span drift for
NO were both larger than the corresponding drift values for N02. The span drift values for NO on
the diesel source are equivalent to 1 to 3 percent of the respective NO span concentrations used.
The span drift values for N02 on the diesel source at idle are equivalent to 4 to 5 percent of the
N02 span concentration used. This drift is a transient phenomenon that can be minimized by
allowing sufficiently long refresh cycles between source measurements.(10)
49
-------
Table 6-18. Data Used to Assess Zero and Span Drift for ECOM A-PLUS Analyzers on
Combustion Sources
Unit A NO
Unit A N02
Unit B NO
Unit B N02
Source
(ppm)
(ppm)
(ppm)
(ppm)
Gas Rangetop*
Pre-Test Zero
1
0
1
0
Pre-Test Span
20
11
21
11
Post-Test Zero
1
0
1
0
Post-Test Span
20
10
20
10
Gas Water Heater* *
Pre-Test Zero
1
0
1
0
Pre-Test Span
100
16
100
16
Post-Test Zero
2
0
2
0
Post-Test Span
100
15
100
15
Diesel-High RPM***
Pre-Test Zero
0
0
0
0
Pre-Test Span
200
50
200
50
Post-Test Zero
3
1
3
1
Post-Test Span
196
50
198
50
Diesel-Idle****
Pre-Test Zero
3
1
3
1
Pre-Test Span
400
100
400
100
Post-Test Zero
NR
NR
NR
NR
Post-Test Span
390
105
388
104
*Span values 20 ppm NO and 10 ppm N02.
**Span values 100 ppm NO and 15 ppm N02.
***Span values 200 ppm NO and 50 ppm N02.
****Span values 400 ppm NO and 100 ppm N02.
NR: Not recorded.
Table 6-19. Results of Zero and Span Drift Evaluation for ECOM A-PLUS Analyzers
Unit A
Unit B
Pre-Test—
NO
no2
NO
no2
Post-Test
(ppm)
(ppm)
(ppm)
(ppm)
Gas Burner
Zero
0
0
0
0
Span
0
1
1
1
Gas Water Heater
Zero
-1
0
-1
0
Span
0
1
0
1
Diesel Generator-High RPM
Zero
-3
-1
-3
-1
Span
4
0
2
0
Diesel Generator-Idle
Zero*
—
—
—
—
Span
10
-5
12
-4
* Post-test zero readings were not recorded.
50
-------
6.2.3 Measurement Stability
Table 6-20 shows the data obtained in the extended sampling test, in which the ECOM A-PLUS
and reference analyzers sampled diesel emissions at engine idle for a full hour without interruption
or sampling of ambient air. The ECOM data were compared to the average of the reference
analyzer data to assess whether a different trend in the emission data was observed for the ECOM
analyzers relative to the reference analyzers. Table 6-21 shows the results of this evaluation, in
terms of the slopes and standard errors of the NO, N02, and NOx data with time.
Table 6-21 indicates that both the ECOM analyzers and the reference analyzers showed a gradual
decrease in NO and an increase in N02 during the 1-hour sampling period. The trends shown by
ECOM analyzers were not significantly different from those of the reference analyzers. For NO,
N02, or NOx. This result is consistent with the relative accuracy for all three species achieved by
the ECOM analyzers on diesel emissions, as shown in Section 6.2.1.
6.2.4 Inter- Unit Repeatability
The repeatability of test results between the two ECOM analyzers was assessed in those cases
where the data lent themselves to application of a t-test. The resulting t-statistics and associated
p-values are listed in Table 6-22. Highlighted in bold are those p-values less than 0.05, which
indicate a statistically significant difference between the two ECOM A-PLUS units at the 95 per-
cent confidence level. As Table 6-22 shows, significant differences between Units A and B were
found only in relative accuracy and in the slopes of the first NO linearity test. The differences
found indicate the variability that may be expected from one analyzer to the next. Nevertheless,
although some significant differences were found between the two analyzers, the practical
importance of those differences is small. Considering the relative accuracy results (Table 6-17), it
is apparent that statistically significant differences in relative accuracy may exist even when the
two analyzers are equally applicable to the measurement at hand. To show just one example, the
relative accuracy results for Unit A on the diesel generator at idle (Table 6-17) are 2.00, 5.62, and
2.85 percent for NO, N02, and NOx, respectively. These results may differ significantly from
those for Unit B (1.33, 4.00, and 1.82 percent, respectively), but either unit would be more than
adequate for determining emissions from that source. The fine degree of discrimination provided
by the statistical tests should not obscure the fact that the two ECOM A-PLUS analyzers
essentially worked equally well throughout the verification tests.
6.3 Other Factors
In addition to the performance characteristics evaluated in the laboratory and source tests, three
additional factors were recorded: analyzer cost, data completeness, and maintenance/
operational factors.
51
-------
Table 6-20. Data from Extended Sampling Test with Diesel Generator at Idle, Verification of ECOM Analyzers
Unit A NO
(ppm)
Unit A N02
(ppm)
ECOM Analyzer Data
Unit A NOx Unit B NO
(ppm) (ppm)
Unit B N02
(ppm)
Unit B NOx
(ppm)
14ANO
(ppm)
14A N02
(ppm)
Reference Analyzer Data
14A NOs 10 NO
(ppm) (ppm)
10 no2
(ppm)
10 NOx
(ppm)
1
333
142
475
330
140
470
330.1
137.2
467.2
327.7
138.7
466.3
2
339
143
482
335
142
477
332.0
137.2
469.2
329.7
138.7
468.3
3
335
144
479
332
142
474
330.1
128.8
458.8
328.7
127.0
455.7
4
333
145
478
329
143
472
331.0
130.9
461.9
329.7
128.1
457.7
5
331
145
476
327
142
469
330.1
130.9
460.9
328.7
129.1
457.8
6
333
146
479
329
144
473
332.0
133.0
465.0
330.7
131.3
461.9
7
328
145
473
324
143
467
320.2
134.9
455.2
320.7
133.3
454.1
8
329
147
476
326
144
470
323.2
135.0
458.2
323.7
133.3
457.1
9
324
146
470
321
144
465
318.3
138.1
456.3
316.8
137.6
454.3
10
327
147
474
324
144
468
324.2
137.1
461.3
320.7
135.5
456.2
11
328
147
475
321
145
466
314.3
147.5
461.8
310.8
147.1
457.9
12
324
148
472
324
146
470
319.2
141.2
460.5
319.7
137.6
457.3
13
330
150
480
327
148
475
324.2
141.3
465.5
321.7
140.7
462.5
14
330
148
478
327
146
473
326.1
134.0
460.1
322.7
133.3
456.1
15
333
149
482
329
147
476
331.0
134.0
465.1
326.7
134.4
461.1
16
332
148
480
327
146
473
326.1
134.0
460.1
322.7
133.3
456.1
17
331
149
480
328
146
474
328.1
134.0
462.1
324.7
132.3
457.0
18
335
149
484
331
147
478
331.0
134.0
465.1
328.7
132.3
461.0
19
334
150
484
332
147
479
326.1
141.3
467.5
325.7
137.6
463.3
20
331
150
481
327
147
474
324.2
140.3
464.4
323.7
134.4
458.1
21
332
150
482
328
148
476
325.1
140.3
465.4
324.7
135.5
460.2
22
332
150
482
328
148
476
324.2
141.3
465.5
323.7
136.5
460.2
23
330
150
480
325
147
472
328.1
131.9
460.0
321.7
132.3
454.0
24
331
150
481
326
148
474
323.2
135.0
458.2
328.7
122.8
451.5
25
327
150
477
324
148
472
324.2
133.9
458.1
329.7
122.8
452.5
26
326
150
476
322
148
470
321.2
138.1
459.3
316.8
135.4
452.2
27
318
150
468
315
148
463
311.4
143.2
454.6
306.8
140.7
447.5
28
320
151
471
317
149
466
319.2
134.9
454.2
313.8
134.4
448.2
29
318
151
469
313
149
462
310.4
145.3
455.7
305.8
141.8
447.6
30
324
151
475
322
149
471
324.2
130.8
454.9
321.7
125.9
447.7
-------
Table 6-20. Data from Extended Sampling Test with Diesel Generator at Idle, Verification of ECOM Analyzers (continued)
Unit A NO
(ppm)
Unit A N02
(ppm)
ECOM Analyzer Data
Unit A NOx Unit B NO
(ppm) (ppm)
Unit B N02
(ppm)
Unit B NOx
(ppm)
14ANO
(ppm)
14A N02
(ppm)
Reference Analyzer Data
14A NOs 10 NO
(ppm) (ppm)
10 no2
(ppm)
10 NOx
(ppm)
31
324
151
475
319
149
468
316.3
141.2
457.5
310.8
139.7
450.5
32
320
152
472
315
150
465
311.4
147.5
458.8
304.9
144.9
449.8
33
320
153
473
319
151
470
314.3
145.4
459.7
308.8
140.7
449.5
34
322
152
474
318
150
468
315.3
144.4
459.7
309.8
140.7
450.5
35
325
152
477
325
150
475
316.3
145.4
461.7
313.8
140.7
454.5
36
327
151
478
325
149
474
324.2
135.0
459.2
317.8
131.2
449.0
37
331
151
482
328
149
477
323.2
136.0
459.2
317.8
132.3
450.0
38
329
151
480
325
149
474
321.2
140.2
461.4
317.8
130.2
447.9
39
332
151
483
328
150
478
322.2
143.4
465.6
318.8
130.2
448.9
40
328
151
479
321
149
470
323.2
143.4
466.6
319.7
136.5
456.3
41
324
151
475
320
149
469
323.2
133.9
457.1
315.8
131.2
447.0
42
323
151
474
319
149
468
318.3
134.9
453.2
311.8
128.0
439.8
43
321
150
471
319
149
468
320.2
138.1
458.3
314.8
132.3
447.0
44
319
152
471
313
150
463
315.3
140.1
455.5
305.8
139.6
445.5
45
310
151
461
304
149
453
308.4
137.9
446.4
298.9
133.3
432.2
46
307
153
460
302
151
453
309.4
133.7
443.2
300.9
132.2
433.1
47
305
154
459
302
152
454
311.4
133.8
445.2
301.9
132.2
434.1
48
309
153
462
305
151
456
308.4
142.2
450.6
297.9
139.6
437.5
49
306
154
460
301
152
453
304.5
141.0
445.6
294.9
136.4
431.3
50
306
154
460
302
152
454
303.5
142.1
445.6
296.9
136.4
433.3
51
306
154
460
302
152
454
308.4
141.1
449.5
299.9
146.0
445.9
52
303
154
457
299
152
451
302.5
143.1
445.7
294.9
137.5
432.4
53
301
154
455
297
152
449
296.7
145.1
441.8
289.0
137.5
426.4
54
305
154
459
301
152
453
300.6
143.1
443.7
294.9
135.4
430.3
55
299
154
453
295
152
447
299.6
142.0
441.6
293.9
135.4
429.3
56
302
155
457
298
153
451
301.6
148.4
449.9
294.9
140.7
435.6
57
306
155
461
303
153
456
302.5
148.4
450.9
295.9
140.7
436.6
58
303
156
459
298
154
452
300.6
153.6
454.2
292.9
144.9
437.8
59
302
157
459
298
155
453
303.5
143.1
446.7
294.9
139.6
434.5
60
304
157
461
299
155
454
302.5
145.2
447.8
294.9
140.7
435.6
-------
Table 6-21. Results of Evaluation of Measurement Stability for ECOM A-PLUS Analyzer
Unit A
Unit B
Reference Units
NO
no2
NOx
NO
no2
NOx
NO N02 NOx
Slope
-0.554
0.178
-0.375
-0.568
0.184
-0.384
-0.545 0.123 -0.423
(Std Err)
(0.044)
(0.009)
(0.045)
(0.045)
(0.008)
(0.047)
(0.043) (0.034) (0.036)
Difference in Slopes
(ppm/min)
-0.009
0.057
0.048
-0.023
0.062
0.039
— — —
(Std Err)
(0.023)
(0.033)
(0.027)
(0.023)
(0.033)
(0.029)
Table 6-22. Summary of Repeatability
Unit A vs. Unit B
NO
no2
NOx
First Linear
Intercept
t-statistic
0.030
-0.378
___
Regression
p-value*
0.977
0.714
—
Slope
t-statistic
-21.481
0.078
—
p-value
<0.001
0.939
—
Detection Limit
t-statistic
-0.010
-0.595
___
(First Linearity Test)
p-value
0.992
0.556
...
Second
Intercept
t-statistic
0.307
-0.072
...
Linear
p-value*
0.765
0.944
Regression
Slope
t-statistic
0.014
0.267
...
p-value
0.989
0.795
—
Detection Limit
t-statistic
0.544
-0.002
...
(Second Linearity Test)
p-value
0.591
0.998
...
Relative
Gas
t-statistic
2.000
**
2.000
Accuracy
Rangetop
p-value
0.081
**
0.081
Gas Water
t-statistic
8.222
4.000
2.800
Heater
p-value
<0.001
0.004
0.023
Generator-
t-statistic
6.424
11.314
13.034
High ppm
p-value
<0.001
<0.001
<0.001
Generator-
t-statistic
4.642
8.000
6.614
Idle
p-value
0.002
<0.001
<0.001
Measurement
Slope
t-statistic
1.452
-1.954
0.824
Stability
p-value
0.152
0.056
0.413
* p-value < 0.05 indicates that two test units are statistically different at the 5% significance level.
** Unit A and Unit B had exactly the same N02 readings on the gas rangetop emission. The matched-
pairs t-statistic could not be calculated.
54
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6.3.1 Cost
The cost of each analyzer as tested in this verification test was approximately $12,000. This
represents the cost of the analyzers, sampling probe, and sample conditioning system.
6.3.2 Data Completeness
The data completeness in the verification tests was 100 percent for both ECOM analyzers.
6.3.3 Maintenance/Operational Factors
The verification tests were too short to assess the long-term maintenance costs or reliability of the
ECOM analyzers. The analyzers showed no operational difficulties during laboratory or source
testing. The interruption in verification testing of the analyzers was caused by a loss of
temperature control in the heated chamber during the ambient temperature test, and not by a fault
of the analyzers themselves. The ECOM analyzers successfully completed the ambient
temperature test and all other tests when testing was resumed.
55
-------
Chapter 7
Performance Summary
The ECOM A-PLUS analyzers provided linear response, but not quite over their full nominal
ranges of 0 to 4,000 ppm for NO and 0 to 500 ppm for N02. The actual linear ranges for the
ECOM analyzers were about 0 to 3,500 ppm for NO, and about 0 to 450 ppm for N02. Detection
limits estimated from the wide-range linearity test data were 1.2 ppm for N02 and about 4 ppm
for NO. Subsequent combustion source tests indicated NO and N02 detection limits comparable
to the 1 ppm measurement resolution of the analyzers. Response times found were 11 to
37 seconds for NO and about 100 seconds for N02. Drift in zero and span readings obtained
before and after source combustion and laboratory tests varied with the NO and N02 levels to
which the analyzers were exposed. In the worst case, drift in span gas readings amounted to about
5 percent of the span value. Shutting the analyzer off completely overnight had no significant
additional effect on the drift observed. No interference was found from any of the following: 496
ppm CO; 5.03 percent C02; 494 ppm NH3; 590 ppm of total hydrocarbons; 501 ppm of S02; and
451 ppm of S02 in the presence of 388 ppm NO.
Over the tested range of -10 to +10 inches of water (relative to ambient pressure), the sample gas
pressure had no significant effect on the zero or span readings of the ECOM analyzers. Ambient
temperature over the range of 7 to 41 °C (45 to 105°F) also had little impact on zero and span
readings of the ECOM analyzers. For example, NO span values differed by 3 percent or less due
to temperature effects over this range, using a 700 ppm span gas; and N02 span values differed by
7.5 percent or less, using a 140 ppm span gas.
The relative accuracy of the ECOM analyzers was 1.3 to 15.3 percent for NO, N02, and NOx, in
nearly all measurements on a gas rangetop, gas water heater, and a diesel engine at both idle and
high RPM. The only exceptions were conditions in which NO or N02 were present at levels
below 6 ppm. In those cases, the ECOM analyzers were accurate within about their 1 ppm
measurement resolution at those low levels. Relative accuracy for NOx was 12.1 percent or better
with all combustion sources, including one producing less than 10 ppm of NOx. In source testing,
the two ECOM analyzers showed unit-to-unit agreement within 4.2 percent or less at NOx levels
from about 7 ppm to over 450 ppm. The agreement between the two ECOM analyzers was
actually better than that between the two reference analyzers.
Comparison of verification results from the two ECOM analyzers shows only slight differences in
performance, which would be of negligible importance in actual sampling. The performance of the
two analyzers tested was essentially the same.
56
-------
Chapter 8
References
1. Test/QA Plan for Verification of Portable NO/NO 2 Emission Analyzers, Battelle, Columbus,
Ohio, December 1998.
2. U.S. EPA Method 7E, Determination of Nitrogen Oxides Emissions from Stationary Sources
(Instrumental Analyzer Procedure) Code of Federal Regulations, 40 CFR, Ch. 1, Part 60,
Appendix A (1991).
3. Traceability Protocol for Establishing True Concentrations of Gases Usedfor Calibrations
and Audits of Continuous Source Emission Monitors: Protocol Number 7, Research
Triangle Park, NC: U.S. Environmental Protection Agency, Quality Assurance Division, June
1978.
4. Interlaboratory Program to Validate a Protocol for the Measurement of NO 2 Emissions from
Rangetop Burners, GRI-94/0458, Gas Research Institute, Chicago, Illinois, December 1994.
5. Interlaboratory Study to Determine the Precision of an Emission Measurement Protocol for
Residential Gas Water Heaters, GRI-96-0021, Gas Research Institute, Chicago, Illinois,
March 1996.
6. American National Standard (ANSI Z21.1) "Household Cooking Gas Appliances," American
National Standards Institute, 24th Edition, American Gas Association, 1990.
7. Quality Management Plan (QMP) for the ETV Advanced Monitoring Systems Pilot, U. S.
EPA Environmental Technology Verification Program, Battelle, Columbus, Ohio,
September 1998.
8. Portable NOx Analyzer Evaluation for Alternative Nitrogen Oxide Emission Rate
Determination at Process Units, Source Testing and Engineering Branch, South Coast Air
Quality Management District, Los Angeles, CA, September 21, 1994.
9. U.S. EPA Method 5, Determination of Particulate Emissions from Stationary Sources, Code
of Federal Regulations, 40 CFR, Ch. 1, Part 60, Appendix A (1991).
10. Determination of Nitrogen Oxides, Carbon Monoxide, and Oxygen Emissions from Natural
Gas-Fired Engines, Boilers, and Process Heaters Using Portable Analyzers, Conditional
57
-------
Test Method (CTM)-030, U.S. EPA, Office of Air Quality Planning and Standards, Emission
Measurement Center, October 13, 1997.
58
-------
Appendix A
Data Recording Sheets
A-l
-------
Date:
Linearity Test Data Sheet
_ Vendor/Analyzer: _
Form Filled Out By:
Pre-Test Z/Span: Unit A: Zero (NO/NO2)
Unit B: Zero (NO/NO2)
NO Test
Unit A
(NO/NO2)
UnitB
(NO/NO2)
1.
2.
3.
4.
5.
Time Response 6.
7.
Span (NO/NO2) L
Span (NO/NO2) L
NO? Test
Unit A
(NO/NO2)
UnitB
(NO/NO2)
L_
L.
7.
9.
10..
11-.
12..
13..
14..
15..
16..
17..
18..
19..
20..
21.
9.
10.
11.
12.
13.
14.
15.
16.
17.
iiL
19.
20.
21.
Post-Test Z/Span: Unit A: Zero (NO/NO2) / Span (N0/N02) /
UnitB: Zero(NO/NC>2) / Span(N0/N02) /
-------
Interrupted Sampling Data Sheet
Date: Vendor/Analyzer:
Form Filled Out By:
Pre-Shut Down Z/Span:
Date: Time:
Unit A (NO/NO2) Zero / Span
Unit B (NO/NO2) Zero / Span
Post-Shut Down Z/Span:
Date: Time:
Unit A (NO/NO2) Zero / Span
Unit B (NO/NO2) Zero / Span
-------
Date:
Interference Test Data Sheet
Vendor/Analyzer:
Form Filled Out By:
Interference Gas Concentration
Zero
CO 496 ppm
Zero
C02 5.03%
Zero
NH3 494 ppm
Zero
Hydrocarbons 590 ppm
Zero
S02 501 ppm
Zero
SO2 + NO 451 ppm + 393 ppm
Response fNO/NO-A
Unit A UnitB
-------
Flow Rate Sensitivity Data Sheet
Date: - Vendor/Analyzer:
Form Filled Out By:
Flow Rate Data: Unit A Unit B
Tccml (ccrn)
Ambient P
+10inH2O
-lOinEbb
Response Data:
Ambient P
Unit A
(NO/NCM
UnitB
(NO/NO
Zero
NO Span
Zero
NO2 Span
Zero
+10inH2O Zero
NO Span
Zero
NO2 Span
Zero
-lOinE^O Zero
/NO Span
Zero
NO2 Span
Zero
-------
Ambient Temperature Test Data Sheet
Date: Vendor/Analyzer:
Form Filled Out By:
Room Temperature: Response fNO/NCM
Unit A UnitB
Zero / /
NO Span / /
NO2 Span / /
Zero / /
Cold Chamber Temperature:
Zero / /
NO Span / /
NO2 Span / !_
Zero / !_
Heated Chamber Temperature:
Zero / L
NO Span / /
NO2 Span / L
Zero / !_
Room Temperature:
Zero
NO Span
NO2 Span
Zero
-------
Accuracy Test Data Sheet: Rangetop Combustion
Date Vendor Analyzer:
Form Filled Out By:
Pre-Test Zero/Span
Calibration Gas & Concentration: Instrument Range:
Calibration Gas & Concentration: Instrument Range:
Unit 14A: Zero (NO/NCtyNOx) / / Span (N0/N02/N0x)
Unit 10: Zero (N0/N02/N0x) / / Span (NO/NOz/NOx) / I
Unit 14A Unit 10
(N0/N02/N0x) (N0/N02/N0x)
1. / / _/
2. / / /
3. / / /
4. / / /
5. / / /
6. / / /
7. / I /
8. / / /
9. / / /
Post-Test Zero/Span
Calibration Gas & Concentration: Instrument Range:
Calibration Gas & Concentration: Instrument Range:
Unit 14A: Zero (N0/N02/N0x) / / Span (N0/N02/N0x)
Unit 10: Zero (NO/NOz/NOx) / / Span (N0/N02/N0x) _/_/
Mod-1:01/17/99
-------
Accuracy Test Data Sheet: Water Heater Combustion
Date Vendor Analyzer:
Form Filled Out By:_
Pre-Test Zero/Span
Calibration Gas & Concentration: Instrument Range:
Calibration Gas & Concentration: Instrument Range:
Unit A: Zero (NO/N02/NOx) / / Span (N0/N02/N0x) / /
Unit B: Zero (NO/N02/NOx) / / Span (N0/N02/N0x) / /
Unit A Unit B
(NO/N02/NOx) (N0/N02/N0x)
1. /
2. /
3. /
4. /
5. /
6. /
7. /
8. /
9. I
Post-Test Zero/Span
Calibration Gas & Concentration: Instrument Range:
Calibration Gas & Concentration: Instrument Range:
Unit A: Zero (NO/N02/NOx) / / Span (NO/N02/NOx)
Unit B: Zero (NO/N02/NOx) / / Span (N0/N02/N0x)
Mod-1:01/17/99
-------
Accuracy Test Data Sheet: Diesel-Engine Combustion
Date Vendor Analyzer
Form Filled Out By: __
Pre-Test Zero/Span
Calibration Gas & Concentration: Instrument Range:
Calibration Gas & Concentration: Instrument Range:
Unit 14A: Zero (N0/N02/N0x) / / Span (N0/N02/N0x) /
Unit 10: Zero (N0/N02/N0x) / / Span (N0/N02/N0x) /
Unit 14A Unit 10
(N0/N02/N0x) (N0/N02/N0x)
1. / / /
2. / / /
3. / / /
4. / / /
5. / / /.
6. L
7. / / ./.
8. /
9. / / /.
Post-Test Zero/Span
Calibration Gas & Concentration: Instrument Range:
Calibration Gas & Concentration: Instrument Range:
Unit 14A: Zero (N0/N02/N0x) / / Span (N0/N02/N0x) /
Unit 10: Zero (N0/N02/N0x) / / Span (N0/N02/N0x) /.
Mo-1: 01/17/99
-------
Measurement-Stability Test Data Sheet: Diesel-Engine Combustion
Date Vendor Analyzer
Form Filled Out By:
Diesel-Engine Load:
Time Unit A
(t+min#) (N0/N02/N0x)
I- / /
2. / /
3.
4. / /
5. / /
6. / /
7. / /
8. / /
9- / /
10. / /
II- / /
12. / /
13. / /
14. / /
15. / /
16. / /
17. / /
18. / /
19- / /
20. / /
21. / /
22 / /
23. / /
24. I /
25. / /
26. / /
27.
28. / /
29. / /
Unit B
(N0/N02/N0x)
30.
-------
Measurement-Stability Test Data Sheet: Diesel-Engine Combustion
Date Vendor Analyzer:
Form Filled Out Bv:
Diesel-Engine Load:,
Time
(t + min#)
31.
32.
33.
34.
35.
36.
37.
38.
39.
40.
41.
42.
43.
44.
45.
46.
47.
48.
49.
50.
51.
52
53.
54.
55.
56.
57.
58.
59.
Unit A
(N0/N02/N0x)
Unit B
(N0/N02/N0x)
60.
-------
Appendix B
External Technical Systems Audit Report
B-l
-------
Environmental Technology Verification Program
Advanced Monitoring Systems Pilot
Air Monitoring Systems
N0/N02 Monitors Verification Test
January 20-21,1999 Audit
Audit Report: ETVAMS001
Revision 1
d Elizabeth A. Betz r _
Elizabeth T. Hunike -
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ETV AMS Air Audit
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1.0 Audit Information
1.1 Auditors:
Elizabeth A. Betz
Human Exposure & Atmospheric Sciences Division
U. S. EPA, NERL (MD-77)
Research Triangle Park, NC 27711
(919)541-1535
Elizabeth T. Hunike
Atmospheric Methods & Monitoring Branch
Human Exposure & Atmospheric Sciences Division
U. S. EPA, NERL (MD-46)
Research Triangle Park, NC 27711
(919) 541-3737
1.2 Dates of Audit: January 20-21, 1999
1.3 Location of Audit: Battelle Memorial Institute, Columbus, Ohio
1.4 Battelle Staff Interviewed and/or Observed:
Karen Riggs ETV AMS Pilot Manager
Susan Abbgy QA/QC Reviewer
Sandy Anderson QA Manager
Verification Test Team:
Tom Kelly Verification Test Leader
Joe Tabor Laboratory Verification Testing
Jim Reuther Emission Source Verification Testing
Steve Speakman Operator, Emission Sources/Reference Method
2.0 Background
Throughout its history, the U.S. EPA has evaluated technologies to determine their effectiveness in
preventing, controlling, and cleaning up pollution. EPA has expanded these efforts by instituting the
Environmental Technology Verification Program (ETV) to verify the performance of a larger number of
innovative technical solutions to problems that threaten human health or the environment. The goal of
ETV is to verify the environmental performance characteristics of commercial-ready technology through
the evaluation of objective and quality assured data, so that potential purchasers and permitters are
provided with an independent and credible assessment of what they are buying and permitting. The
ETV Program Verification Strategy outlines the goals, operating principles, pilot selection criteria, and
implementation activities. ETV includes twelve pilot projects. In these pilots, EPA is using the
expertise of partner verification organizations to design efficient processes for conducting performance
tests of innovative technologies. The implementation activities involve forming stakeholder groups who
identify technologies needing verification, designing a generic verification protocol and then Test/QA
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ETV AMS Air Audit
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Plans for the specific technology to be verified. The verification tests are run on the identified
technologies wishing to participate and verification statements based on the test results are generated.
One pilot, entitled Advanced Monitoring Systems (AMS), is to verify the performance of commercially
available technologies used to monitor for environmental quality in air, water and soil. This pilot is
managed by EPA's National Exposure Research Laboratory in Research Triangle Park, North Carolina
and their verification partner for the AMS pilot project is Battelle Memorial Institute, Columbus, Ohio.
This pilot has been divided into three sub-pilots, each looking at monitoring systems for a specific
media, air, water and, eventually, soil. The Air AMS portion has evolved to the point of actually
running verification tests on available air monitoring instrumentation.
3.0 Scope of Audit
3.1 Audit Preparation. The auditors reviewed the following documents pertinent to the ETV AMS
Pilot:
a. Environmental Technology Verification Program Quality and Management Plan for the
Pilot Period (1995-2000), May 1998
b. Environmental Technology Verification Program Quality Management Plan for the
ETV Advanced Monitoring Systems Pilot, September 1998
c. Test/QA Plan for Verification of Portable NO/NO 2 Emission Analyzers, December 4,
1998
d. U. S. EPA Method 6C, Determination of Sulfur Dioxide Emissions from Stationary
Sources (Instrumental Analyzer Procedure)
e. U. S. EPA Method 7E, Determination of Nitrogen Oxides Emissions from Stationary
Sources (Instrumental Analyzer Procedure)
Based on the above material, a checklist was prepared. The U. S. EPA ETV AMS Pilot Manager,
Robert G. Fuerst, was provided the checklist prior to the audit. The completed checklist for this audit is
attached.
3.2 Audit Scope.
The audit encompassed a technical systems audit of a verification test (VT) on nitrogen oxides monitors
at Battelle. A technical systems audit is a qualitative onsite audit of the physical setup of the test. The
auditors determine the compliance of testing personnel with the test/QA plan. The auditors were on site
from Wednesday afternoon through Thursday afternoon. The technical systems audit was performed on
the flow rate and ambient temperature of the laboratory portion of the VT and the relative accuracy
tests with the gas cooktop, water heater and a portion of the lower range emissions of a diesel
generator. No performance evaluations were conducted as a part of this audit.
4.0 Executive Summary
4.1 The VT is well-managed, particularly considering its complexity. All personnel appeared to be
well-trained for their particular duties. All involved showed enthusiasm and ingenuity during the VT.
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ETV AMS Air Audit
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4.2 The significant findings of this audit, cited in paragraph 5.0 below, had also been found by
Battelle's QA staff during their audit earlier in the VT.
4.3 The technical systems audit showed that the VT personnel were very familiar with the Test/QA
Plan. With one exception, differences for this VT from the original Test/QA Plan were well
documented by deviation reports on file at Battelle. The deviation report format includes a date, cites
the deviation, provides an explanation of the deviation and requires an approving Battelle signature. It
was impressive that the deviation reports were present and were completed up front. The one
difference from the VT that was not cited in a deviation report was that Battelle had intended to run an
analyzer already on hand completely through the VT before the first vendor's analyzer. This was not
done nor was a deviation report generated. The remaining differences were cited in the deviation
reports.
5.0 Major Findings
5.1 Undocumented Deviation from the Test/QA Plan. The undocumented deviation was from
section 5.6, Test Schedule, and stated "to avoid bias in testing of the first analyzers through the
sequence, Battelle's personnel will first conduct the entire test sequence using an analyzer already on
hand at Battelle. Testing will then continue with analyzers named in section 2.4." Due to a delay in the
arrival of the protocol gases used in the VT, Battelle did not run one of their instruments through the
test sequence. As a result a leak in the gas supply system in the laboratory test portion was not detected
before the first vendor started the VT sequence.
5.2 Initial Calibration of Instruments for Emission Source Testing. The Test/QA Plan states that
"the chemiluminescent monitors to be used for Method 7E reference measurements will be subjected to
a 4-point calibration with NO prior to the start of verification testing, on each measurement range to be
used for verification." The initial Emission's portion of the VT was started on January 13, 1999. There
was no 4-point calibration with NO recorded in the Emission's VT laboratory notebook prior to the
January 13th testing. This finding is also a finding in Battelle's Internal Audit conducted during the first
week of the VT.
6.0 Results of Technical Systems Audit
6.1 Organization. The Battelle ETV AMS VT team consisted of four members. All team members
were very knowledgeable of the procedures and helpful to the auditors. There are also two Battelle
Quality Assurance staff members that are members of the ETV AMS team. Both were available and
very helpful to the auditors. These Battelle QA staff members are responsible for running the internal
audits required by the ETV related QMPs. One such audit was conducted the week prior to this EPA
audit.
6.1.1 The Test/QA Plan stated that a Dr. Agnes Kovacs would be providing statistics and data
analysis for this VT. One of the documented deviations was that Dr. Kovacs would not be participating
in the VT as she has left Battelle. Although the deviation report stated that someone in the Statistics
and Data Analysis Department would be taking her place, there was no indication in the deviation report
as to who it would be.
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ETV AMS Air Audit
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6.2 Gas Cylinder Certifications. A review of the gas cylinder certifications uncovered some minor
discrepancies. The expiration date on two of the cylinder certifications did not match the expiration
date on the cylinders. The discrepancy was corrected by the gas manufacturer on the day of inspection.
Battelle did not initially have certifications for the gas cylinders used in the source test. The gas
manufacturer was contacted by phone and faxed in certifications for 3 of the 4 cylinders. The original
certificates were later located on one of the team member's desk. The gas cylinder for one of the
certificates reviewed was not found among the ETV VT equipment.
6.3 Temperature Sensor Certification. The certificate in the notebook maintained for the Laboratory
Test Portion was for Model 402A, Serial # 40215 Temperature Indicator. This indicator was not seen
by the Auditors. The Temperature Indicator used in the Laboratory Test portion to read the
temperature of the monitors during the Ambient Test was Model 400A, decal # LN-560558. The
certificate was not in the notebook, however, the indicator did have a label on it that stated that it was
certified 1-7-99. Discussion with Susan Abbgy, after the audit, clarified that LN-560558 was an internal
Battelle laboratory number and that the manufacturer's serial number on LN-560558 was 40215.
However, the certificate did reflect an incorrect model number for Temperature Indicator Serial #
40215.
6.4 Deviation Reports. The dated reports cited the deviation, provided an explanation/justification of
the deviation and required an approving Battelle signature. It was impressive that the deviations reports
were present and were completed up front.
6.4.1 The Flow Rate Sensitivity Test procedure had three deviation reports. The Test/QA Plan
called for the use of 60% span value during the test. A deviation report cited that this was changed to
70% span value to correlate to the Linearity Test. The two other reports related to the Flow Rate
Sensitivity Test were very similar and called for a change in the order of the procedure to reduce the
amount of plumbing changes required.
6.4.2 The Ambient Temperature Test had one deviation report. The order of the test was
changed. The procedure called for doing a cooled chamber test first and then hot. The deviation report
stated that all VTs will be done in the reverse order. The reason for the deviation was based on
discussions with the vendors that indicated the rise in temperature after exposure to NO may cause
more drift. The order was reversed to more clearly observe any drift.
6.4.2.1 During the Ambient Temperature Test observed, slight changes were made to
accommodate the mass of the monitors. The vendor's monitors were larger than previous monitors and
generated and held heat longer. The door to the heated chamber, once the monitors reached its
temperature, had to remain slightly ajar to hold the chamber temperature at a constant value. The
heated monitors were then placed in the cold chamber (a standard household refrigerator). The heat
given off by the monitors raised the temperature in the refrigerator over 100°F. To obtain a cooled
chamber reading the team members relocated the monitors to the outdoors which produced a cooled
ambient temperature within the 45°F ±5°F for the one hour required for temperature equilibration and
the additional time required to perform the zero and span check. This was a fine example of the
ingenuity the VT team members showed to accommodate differences in monitors.
6.4.3 Interference Test. The mixture of S02 and NO for the Interference Test was changed
from interferant levels of 250 ppm each of S02 and NO to interferant levels of 451 ppm S02 and 393
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ETV AMS Air Audit
Page 5
ppm NO. According to the deviation report, this change was made because the NO standard available
wasn't at the anticipated concentration when the Test/QA Plan was written.
6.4.4 Source Testing.
6.4.4.1 The Test/QA Plan cited the use of two diesel generators for the Source Test.
The selection of these generators was made based on studies that Battelle had used in the past that
provided a database of emission levels generated by these sources. However, these generators were
property of the Air Force and were unavailable at the time of the VT due to military activities in the
Middle East. Battelle substituted one generator they had on site and collected emission data at two
speeds to provide two higher emission levels than previously provided by the cooktop or water heater.
This substituted generator produced two levels of emissions; however, neither level was over 500 ppm
of NO. The database that Battelle had on the originally planned generators showed that one model
would produce ranges between 100-1000 ppm NOx and the second model would produce ranges
between 600-2300 ppm NOx. The impact of this change is that there will be no verification for higher
ranges.
6.4.4.2 The oxygen sensor was not used during the source test. This VT's focus was
the verification of NO/N02 levels and not to compare oxygen data. Source stability will be documented
by NOx measurements instead of oxygen measurements. The source stability for the water heater and
the cooktop is also documented in two Battelle reports on data from these specific sources used in
interlaboratory comparisons from 1994 through 1998. The initial generators planned for the VT also
had similar data bases. The source stability of the generator actually used was verified by data collected
in December and January prior to the VT. The actual data collected by the reference monitors during
the VT also verified the source stability.
6.4.4.3 ThermoEnvironmental Models 14A and 10 NO/N02 analyzers were used for the
reference method. The Test/QA Plan called for identical Beckman Model 955 monitors. The reason
stated in the deviation report for the substitution was that the Thermo Instruments are newer and are in
more current use.
6.4.4.4 Triplicate readings of calibration points were not run in the calibration of the
reference method analyzers. Method 7E does not require triplicate readings of calibration points.
6.4.4.5 One deviation report addressed the use of unheated sample lines and poly tubing.
The Test/QA Plan is based on EPA Method 7E but based on Battelle's own experience with the sources
in the laboratory environment an unheated inlet was used. Additionally it should be noted that the VT is
conducted inside in a laboratory setting with controlled temperature and humidity and Method 7E is for
stack sampling. The only comment on this deviation report is that the originator of the deviation signed
the report instead of obtaining an independent approval signature.
6.5 Leak Detected in the System in the Laboratory Test Portion. During the first vendors's
laboratory test portion, a leak was detected in the system. The data sheets for the laboratory test
portion of the first vendor's VT showed a note that a leak was detected and the vendor recorded
oxygen levels. Also noted on the data sheet was a correction factor that would be used on the vendor's
data that was made based on the vendor's oxygen readings. The correction factor notes were brought
to the auditor's attention by Battelle's QA staff. Because the VT did no verification of oxygen levels,
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ETV AMS Air Audit
Page 6
the correction factor may be inaccurate. As part of the documentation for that VT, the accuracy of the
oxygen readings by the vendor needs to be addressed.
6.6 Initial Calibrations and Tests in the Source Laboratory. As stated under major findings,
paragraph 5.2 above, the initial calibrations of the chemiluminescent monitors used as the Method 7E
references were not done before the first VT. In addition no interference test was conducted prior to
1-18-99 which was after the second VT. However, all subsequent VTs had the required initial
calibration and interference tests. This was also a finding in Battelle's internal audit conducted a week
earlier. Battelle will need to address this in the VT report.
6.7 Corrections of Data Sheets. In most instances, corrections made on the data sheets followed
Good Laboratory Practices; however, some did not (i.e., one line was not drawn through the incorrect
entry and the correction was not dated and initialed).
6.8 Source Laboratory Notebook Entries. The initial entries were difficult to follow because the
writing was almost illegible and there were missing entries. However, with the exception of the first
VT, the four-point initial calibrations are recorded and the time and dates of the VTs are also shown.
The actual source test data are recorded on data sheets. The notebook is only used to record the
calibration and interference test data on the reference monitors and to record the times, dates and
comments on the VTs.
-------
Checklist for Verification Test (VT) of Portable N0/N02 Emission Analyzers
Date(s): January 20-21. 1999 Location: Battelle. Columbus. Ohio
Personnel Involved in the Audit:
Titles
Names
EPA Auditor(s):
| Elizabeth Betz
| Elizabeth Hunike
Battelle QA Rep present:
QA/QC Reviewer
Susan Abbgy
QA Manager
Sandy Anderson
Battelle Auditees:
ETV AMS Pilot Manager
Karen Riggs
Verification Test Leader
Tom Kelly
Laboratory Verification Testing
Joe Tabor
Emission Source Verification
Testing
Jim Reuther
Operator, Emission
Sources/Reference Method
Steve Speakman
Vendor(s) Present:
Horiba
J. David Vojtko
General
Comments
Are the Testers familiar with:
ETV QMP
All staff seem familiar with the
documents and there are copies of each
in the ETV reference notebooks
maintained in the Laboratory and
Source Testing areas
Verification Protocol
Test/QA Plan
QA Manager
Generic Verification Protocol:
Finalized?
The Protocol has been finalized and is
in the process of being placed on the
web.
Test Plan:
Approved and Signed?
The test plan has been reviewed by the
vendors. Approval signatures have
been received as vendors have arrived
to participate in the verification test
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ETV AMS Pilot
N0/N02 Checklist
Page 2
Technologies:
-Electrochemical (EC) sensors
Testo's Model 350 electrochemical NO and N02 analyzer
Also by direct measurement: 02, CO, S02, Stack Temperature, Stack Pressure
By calculation: C02
Energy Efficiency System's ENERAC 3000SEM electrochemical NO & N02 analyzer
Also by direct measurement: 02, CO, S02, C02, Stack Temperature
TSI's COMBUCHECK electrochemical NO or N02 analyzer
ECOM's A-Plus electrochemical NO and N02 analyzer
Also by direct measurement: 02, CO, S02, Stack Temperature, Stack Pressure
By calculation: C02
-Chemiluminescence emitted from the reaction of NO with 03 produced within the analyzer
Horiba's Model PG-250 portable gas analyzer
Also by direct measurement: 02, CO, S02, C02
The audit was run during the second week of the Test Plan and the 4th vendor was being verified. The
vendor was Horiba.
Pre-Test Requirements:
Dry Gas Meter: Initial Calibration Date: See Below
Accurate within 1% and measured in ft3
Calibrated against a volumetric standard within 6 months preceding VT
During VT, checked at least once, against reference meter
In-Line Meter. Serial # 1036707. Rockwell R-275. certified 1/18/99
Reference Meter model DTM 115 certified 9/22/98
Temperature Sensor/Thermometers: Initial Calibration Date: See Below
Calibrated against a certified temp, measurement standard within 6 months preceding VT
During VT, checked at least once, against an ASTM mercury-in-glass reference thermometer at
ambient temperature and be within 2%.
Temperature Indicator. Serial #40215. Model 402A. certified 1/7/99. certificate available but didn't
locate this indicator. Temp indicator in Lab. LN-560558. Model 400A. certified 1/7/99.
Oxygen Monitor: Initial Calibration Date:
Calibrated within the last six months
During VT, checked once every test day by sampling of ambient air
During operation of one combustion source, assessed for accuracy
Did not use as cited in a documented deviation report.
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ETV AMS Pilot
N0/N02 Checklist
Page 3
Chemiluminescent Monitors to be used for Method 7E
Initial Interference Response conducted prior to VT Date: See Below
Measurement System Preparation prior to VT Date: See Below
Analyzer Calibration Error prior to VT Date: See Below
Sampling System Bias Check prior to VT Date: See Below
N02 to NO Conversion Efficiency Date: See Below
Calibrations Initial Calibration Date: See Below
4-point calibration with NO & N02 prior to VT, on each measurement range
For Horiba's VT both were run 1/20/99. however neither were done before first VT. Interference
response was conducted prior to Horiba's VT but not prior to the first VT.
Each point shall be prepared in triplicate - cited in a documented deviation report
Calibration error requirement: <±2% of span for the zero, midrange and high-range calibration
gases.
Zero and Span checks done daily AM and PM during the VT
Observed AM checks before source test, not present for PM.
Gas Dilution System Initial Calibration Date: 12/16/98
Flow measurement/control devices calibrated prior to VT by soap bubble flow meter.
Calibration Standards:
EPA Protocol 1 Gases (Calibration paperwork available):
NO in N2, High Range: 80-100% of span
Mid-Range: 40-60% of span
Zero: Concentration <0.25 % of span, ambient air
Protocol Cylinder # ALM057210 expiration date on certificate and cylinder tag did not match.
Cylinder # ALM017108 expiration date on certificate and cylinder tag did not match.
Certificate available for Cylinder # ALM036273 but could not locate cylinder.
Certificates for Source Lab cylinders (AAL14789. ALM014050. AAL17452. ALM015489N) could not
be initially located.
Sample Location:
Minimum of 8 duct diameters downstream and 2 duct diameters upstream of flow disturbances
and center point of the flue vent
The minimal distances from flow disturbances cited in the Reference Method relate to particulate and
are not critical for gases and were not used. Vendor's instrument sampling tubes were placed beside
those for the reference instruments.
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Day One - Laboratory Tests:
Linearity: (response over the full measuring range) - Not Observed
21 measurements for each analyte (NO, N02 or NOx)
Zero six times, each other three times
Calibration points used: 0, 10, 20, 40, 70 and 100% of the analyzer's measuring range
Horiba: 0-25, 0-50, 0-100, 0-250, 0-500, 0-1000, 0-2500
0, 250, 500, 1000, 1750 for 0-2500
Initial Zero and Span check?
After every three points, pure dilution gas provided and the analyzers' readings recorded?
Is the order of concentration points followed?
Final Zero and Span Check?
Linearity test was not observed; however, data sheets were examined. The 100% span used for the
Horiba was 500 ppm. The laboratory log sheets verified that 21 measurements were made, the order of
concentration points cited was used, and that initial and final Zero and Span checks were done.
Response Time Determinations - Not Observed
Analyzer's response recorded at 10 second intervals during Response Time check (estimated to be 30
readings)
Detection Limit - Not Observed
Detection limit is based on data from zero and 10% readings during Linearity test (9 readings)
Interrupted Sampling (four readings total) - Not Observed
Zero and Span recorded at end of Linearity Test on Day One
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Day Two - Laboratory Tests
Interrupted Sampling continued - Not Observed
Zero and Span are recorded after analyzer has been powered up before any adjustments
Same Span from previous day is used
Interference Tests: - Not Observed
Actual concentrations were obtained from the data sheets. A documented deviation cited the change in
the SOt and NO interferant concentrations.
Interferant
Interferant Concentration
Target Analyte
CO
500 ppm - Actual concentration used - 496 ppm
NO, N02, NOx
o
o
N)
5% - Actual percentage used - 5.03%
NO, N02, NOx
so2
500 ppm - Actual concentration used - 501 ppm
NO, N02, NOx
nh3
500 ppm - Actual concentration used - 494 ppm
NO, N02, NOx
Hydrocarbon Mixture
~ 500 ppm Cl3 -100 ppm C2, ~ 50 ppm C3 and C4
Hydrocarbon concentration used - 590 ppm
NO, N02, NOx
S02 and NO
250 ppm each - Actual concentration used -
451 ppm S02 & 393 ppm NO
NO, N02, NOx
Analyzer zeroed first and recorded
Interferant gas supplied, analyzer stabilized and analyte concentrations recorded (6 readings)
Flow Rate Sensitivity (9 readings) - Not Observed
Type of flow measuring device: automated bubble flowmeter, rotameter, or other
Ambient atmosphere and ambient flow rate recorded
Zero gas provided and recorded, span gas provided and recorded, zero provided again and recorded
Adjust pressure in system to +10" of water, record flow rate, repeat zero, span and zero
Adjust pressure in system to -10" of water, record, flow rate, repeat zero, span and zero
A leak was detected during the running of the flow rate test for the first vendor. The data sheets reflect
this and also indicate a correction factor would be used in the calculations. The correction factor was
based on the O^ value recorded on the vendor's monitors.
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Ambient Temperature (12 readings)
Room Temperature recorded (assumed to be above 45°F and below 105°F)
Zero and Span and Zero done at each temperature
Instrument allowed to equilibrate to chamber temperature for 1 hour
The ambient temperature test was observed. Room temperature readings were done first. Then the
monitors were placed in a heated chamber at 105°F at 13:24 and first readings were at 14:45. The
chamber door had to remain slightly aiar to keep the temperature constant. Next the monitors were
placed in the cooling chamber which was a household refrigerator. The heated monitors kept
overheating the refrigerator. After the initial hour to equilibrate the monitors, the refrigerator
temperature was at 110° F. To obtain the cooled ambient temperature needed for the test, the monitors
were placed out the laboratory window onto the adjacent roof for an hour and were brought to 47°F.
The cooling chamber test readings were taken from 6:38 pm to 6:43 pm.
This showed great ingenuity of the laboratory test staff to obtain the required ambient conditions for the
test.
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Day Three and Four - Source Tests
Method 7E
Measurement System Performance - Chemiluminescent Monitors
Thermo Environmental Instruments Model 10 and Model 14 A. Data were recorded off a voltage
meter attached to each instrument and voltage readings were then converted to concentrations.
The Fluke voltage meter attached to Model 14A was calibrated 11/2/98 and the one attached to
Model 10 was calibrated 11/3/98.
Zero Drift: <± 3% of the span over the period of each run
Calibration Drift: <± 3% of the span over the period of each run
Interference Check: <±7%
Measurement System Specifications:
A documented deviation cited changes to the sample probe and lines initially indicated to be allowed by
EPA Method CTM-022 but later revised per July 16. 1999 letter from Battelle indicating the changed
was based on Battelle's own experience with the sources used in the laboratory environment.
Sample Probe - Glass, stainless steel, or equivalent
Sample Line - Heated stainless steel or Teflon tubing
Sample Transport Lines - Stainless Steel or Teflon tubing
Calibration Valve Assembly - 3-way valve assembly or equivalent
Moisture Removal System - refrigerator-type condenser or similar device(?) - Ice Chest was used.
Particulate Filter - borosilicate or quartz glass wool or glass fiber mat, non-reactive with NOx,
in-stack or heated out-of-stack
Sample Pump - Leak free pump of any non-reactive material
Sample Flow Rate Control - control valve and rotameter or equivalent
Sample Gas Manifold - any non-reactive material
Data Recorder - strip chart recorder, analog computer or digital recorder;
resolution shall be 0.5% of span
A data recorder was not used. The test data was recorded on log sheets, one filled out by the
vendor on his monitors and one filled out by source laboratory operator for the reference
monitors. Calibrations prior to VT are recorded in a bound notebook. Entries are also made to
indicate the date and times the VTs in the source laboratory were run.
Sampling:
Measurements obtained only after twice the response time has elapsed
Zero and Calibration Drift tests performed immediately preceding and following every run
Adding zero gas & calibration gas (closely approximates the source) at calibration valve
Sampling continues only when zero and calibration drift are within specifications
Emission Calculations: - No calculations were observed
Concentrations are: avg readings (initial & final sampling system bias checks are averaged)
adjusted for the zero and upscale sampling system bias checks
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Relative Accuracy Tests
Low NOx Sources
Gas Cooktop: NO and N02 ranges 1-9 ppm
Must operate continuously during test (can't cycle off)
Must operate at steady-state (See Page 8 or 9)
Condition/Specification
Comments
Analyzers (two each) zeroed and span checked
initially only
/- Span was 20 ppm NO and 10 ppm N02
Sampling probes of analyzers placed beside
reference method probe
/- Lines to instruments are then connected into a
metal tube to top of stove top.
Analyzers are allowed to stabilize
/
After initial readings, probes are switched to
ambient air and stabilized
/
Sample Probes are returned to source for a total
of nine samplings
/
Final zero and span check conducted on analyzer
after each source, using the same span as initial
check
/
The cooktop used in the VT has been used by Battelle in a previous study. The data on the source
levels generated by the cooktop are documented in a Battelle report entitled "An Interlaboratory
Program to Validate a Protocol for the Measurement of MX Emissions from Rangetop Burners." The
data covers 1994 through 1998.
The gas supply for the cooktop is from a certified cylinder without sulfur.
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Water Heater: NO and N02 ranges 10-80 ppm
Must operate continuously during test (can't cycle off)
Must operate at steady-state (See Page 8 or 9)
Condition/Specification
Comments
Analyzers (two each) zeroed and span checked
initially only
/ - Span was 100 ppm NO and 15 ppm N02
Sampling probes of analyzers placed beside
reference method probe
/ - connect in a "T" together
Analyzers are allowed to stabilize
/
After initial readings, probes are switched to
ambient air and stabilized
/
Sample Probes are returned to source for a total
of nine samplings
/
Final zero and span check conducted on analyzer
after each source, using the same span as initial
check
/
The water heater used in the VT has been used by Battelle in a previous study. The data on the source
levels generated by the water heater is documented in a Battelle report entitled "An Interlaboratorv
Study to Determine the Precision of an Emission Measurement Protocol for Residential Gas Water
Heaters." The data covers 1994 through 1998.
The gas supply for the water heater was from the city gas supply. However. Battelle has a gas
chromatograph monitoring the concentration of the gas daily.
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Medium NOx Source
First Diesel Generator: NO and N02 ranges 100-1000 ppm NOx
Must operate at steady-state
Condition/Specification
Comments
Analyzers (two each) zeroed and span checked
initially only
/ - Generator was run at high RPM
Span was 200 ppm NO and 50 ppm N02
Sampling probes of analyzers placed beside
reference method probe
/
Analyzers are allowed to stabilize
/
After initial readings, probes are switched to
ambient air and stabilized
/
Sample Probes are returned to source for a total of
nine samplings
/- initial sampling observed only, auditors
departed
Analyzers are evaluated at three separate load
conditions per generator
Extended sampling interval (one hour) is
conducted during one load condition
See Note Below
Final zero and span check conducted on analyzer
after each source, using the same span as initial
check
Note: The Test/OA Plan called for two specific generators from the Air Force that were unavailable at
the time of the VT. A generator on-site was modified to be both the medium and high source. This
generator was run at a high RPM for the medium source and at idle for the high source. Because of the
noise level at the high RPM. most of the extended sampling interval (one hour) was done during the
high source test and not the medium source. One vendor chose to not submit its monitors to the high
source so its extended sampling interval was done during the medium source (high RPM).
Steady-State:
Temperature changes in the center position of the exhaust of not more than ±10°F;
NOx changes at the center of the exhaust duct of < ±5% relative to the mean over the 15 minute
interval as determined using the EPA reference method
02 changes, at the center of the exhaust duct of < ±0.50% absolute (±5000 ppm) from the mean
sampled over the 15 minute interval.
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High NOx Source - Not Observed
Second Diesel Generator: NO and N02 ranges 600-2300 ppm NOx
Must operate at steady-state
Condition/Specification
Comments
Analyzers (two each) zeroed and span checked
initially only
Sampling probes of analyzers placed beside
reference method probe
Analyzers are allowed to stabilize
After initial readings, probes are switched to
ambient air and stabilized
Sample Probes are returned to source for a total of
nine samplings
Analyzers are evaluated at three separate load
conditions per generator
Extended sampling interval (one hour) is
conducted during one load condition
Final zero and span check conducted on analyzer
after each source, using the same span as initial
check
Note: Instead of a second generator, the generator was run at idle to produce a span of 400 ppm NO
and 100 ppm MX.
Steady-State:
Temperature changes in the center position of the exhaust of not more than ±10°F;
NOx changes at the center of the exhaust duct of < ±5% relative to the mean over the 15 minute
interval as determined using the EPA reference method
02 changes, at the center of the exhaust duct of < ±0.50% absolute (±5000 ppm) from the mean
sampled over the 15 minute interval.
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