July 1999
Environmental Technology
Verification Report
Horiba PG-250
Portable Emission Analyzer
Prepared by
o
Baireiie
, . Putting Technology To Work
Battelle Memorial Institute
Under a cooperative agreement with
U.S. Environmental Protection Agency
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Jmrnd Jmmd
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July 1999
Environmental Technology Verification
Report
Advanced Monitoring Systems
Horiba PG-250
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.
11
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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 com-
munity 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.
Vll
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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 David Vojtko of Horiba
Instruments.
Vlll
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Contents
Notice ii
Foreword vii
Acknowledgments viii
List of Abbreviations xiii
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
5.1.2 Detection Limit 32
6.1.3 Response Time 33
6.1.4 Interrupted Sampling 33
6.1.5 Interferences 33
6.1.6 Pressure Sensitivity 37
6.1.7 Ambient Temperature 39
6.1.8 Zero and Span Drift 40
6.2 Combustion Source Tests 41
6.2.1 Relative Accuracy 41
6.2.2 Zero and Span Drift 45
6.2.3 Measurement Stability 46
6.2.4 Inter-Unit Repeatability 49
6.3 Other Factors 50
6.3.1 Cost 50
6.3.2 Data Completeness 50
6.3.3 Maintenance/Operational Factors 50
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7. Performance Summary 52
8. References 53
Appendix A: Data Recording Sheets A-l
Appendix B: External Technical Systems Audit Report B-l
Figures
Figure 2-1. I Ioriba PG250 2
Figure 3-1. Manifold Test Setup 7
Tables
Table 3-1. Identity and Schedule of Verification Tests Conducted on
Horiba PG-250 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
Horiba PG-250 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 of Horiba PG-250 Analyzers 30
Table 6-lb. Data from N02 Linearity Test of Horiba PG-250 Analyzers 31
Table 6-2. Statistical Results for Test of Linearity 31
Table 6-3. Estimated Detection Limits for Horiba PG-250 Analyzers 32
Table 6-4. Response Time Data for Horiba PG-250 Analyzers 34
Table 6-5. Response Time Results for Horiba PG-250 Analyzers 35
Table 6-6. Data from Interrupted Sampling Test with Horiba PG-250 Analyzers 35
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Table 6-7. Pre- to Post-Test Differences as a Result of Interruption of Operation
of Horiba PG-250 Analyzers 35
Table 6-8. Data from Interference Tests on Horiba PG-250 Analyzers 36
Table 6-9. Results of Interference Tests of Horiba PG-250 Analyzers 36
Table 6-10. Data from Pressure Sensitivity Test for Horiba PG-250 Analyzers 38
Table 6-11. Pressure Sensitivity Results for Horiba PG-250 Analyzers 38
Table 6-12. Data from Ambient Temperature Test of Horiba PG-250 Analyzers 39
Table 6-13. Ambient Temperature Effects on Horiba PG-250 Analyzers 40
Table 6-14. Data from Linearity and Ambient Temperature Tests Used to Assess
Zero and Span Drift of the Horiba PG-250 Analyzers 41
Table 6-15. Zero and Span Drift Results for the Horiba PG-250 Analyzers 41
Table 6-16a. Data from the Gas Rangetop in Verification Testing of Horiba PG-250
Analyzers 42
Table 6-16b. Data from Gas Water Heater in Verification Testing of Horiba PG-250
Analyzers 42
Table 6-16c. Data from the Diesel Generator at High RPM in Verification Testing
of Horiba PG-250 Analyzers 43
Table 6-16d. Data from the Diesel Generator at Idle in Verification Testing
of Horiba PG-250 Analyzers 43
Table 6-17. Relative Accuracy of Horiba PG-250 Analyzers 44
Table 6-18. Data Used to Assess Zero and Span Drift for Horiba PG-250 Analyzers on
Combustion Sources 45
Table 6-19. Results of Zero and Span Drift Evaluation for Horiba PG-250 Analyzers 46
Table 6-20. Data from Extended Sampling Test with Diesel Generator at idle,
Using Horiba PG-250 Analyzers 47
Table 6-21. Results of Evaluation of Measurement Stability for Horiba PG-250 Analyzer .... 49
Table 6-22. Summary of Repeatability 50
xii
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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
Xlll
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SCAQMD South Coast Air Quality Management District
SCR selective catalytic reduction
S02 sulfur dioxide
UHP ultra-high purity
XIV
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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 Horiba PG-250 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 two Model PG-250 chemiluminescent NO
and NOx analyzers manufactured by Horiba Instruments, Inc., Irvine, California. The following is
a description of the Horiba portable emission analyzer based on information provided by the
vendor.
The Horiba Model PG-250 multi-gas portable analyzer is specifically designed for compliance
with 40 CFR 60, Appendix B, as a backup instrument and for conducting relative accuracy test
audits.
The compact (10.2 inches high, 10.2 inches wide, and 20.1 inches deep) and lightweight
(37 pounds) instrument can be hand carried to any test location. The PG-250 provides the user
with simultaneous analyses of CO, C02, 02, NOx, and S02 in flue gas samples. Each gas con-
stituent can be monitored over multiple ranges. The settings include ranges for NOx extending up
Figure 2-1. Horiba PG-250
5*
to 2,500 ppm, four ranges for S02
extending up to 3,000 ppm, five
ranges for CO over the span of 0 to
5,000 ppm and three ranges each for
C02 and 02. The chemiluminescence
NO detector uses a low-temperature
N02 to NO converter to achieve
measurement of NOx, Separate NOx
and NO measurements can be made.
N02 concentrations can be
measured by taking the difference
between the sequential NOx and NO
measurements. The PG-250 manual
states that the NO, concentration in
the sample gas must be less than
6 ppm. At this concentration the
expected life of the N02 converter is
one year; the lifetime of the
converter decreases linearly with N02 concentration above 6 ppm.
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The PG-250 employs non-dispersive infrared detection of S02, CO, and C02; chemiluminescence
detection of NO and NOx; and an electrochemical cell for 02 measurement. Only the NO/NOx
measurement capabilities were verified in this test. The PG-250 also incorporates a built-in sample
conditioner consisting of a dual-stage moisture removal system that includes a gravity drain
separator and thermal-electric cooler. Other sample conditioning components can include acid
mist eliminators, filters, sample pump, condensate drain pump, and a sample flow monitor.
Sampling is accomplished with a 316 stainless steel unheated sample probe equipped with an
external primary filter.
Data may be output from the instrument via 4 to 20 mA analog signals or from the instrument's
RS-232C serial communication port. A large LCD screen also provides real-time display of all
five gas parameters being measured, in addition to the selected measurement ranges for each gas
and the sample flow through the analyzer. In the verification testing reported here, data were read
from the LCD screen and recorded manually on standard data sheets. Menu-driven screens allow
the operator to easily step through instrument functions for selecting ranges and setting span
values when calibrating the instrument.
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Chapter 3
Test Design and Procedures
3.1 Introduction
The verification test described in this report was conducted in January 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.(l) 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)
These tests are listed in Table 3-1.
Table 3-1. Identity and Schedule of Verification Tests Conducted on Horiba PG-250
Analyzers
Test Activity Date Conducted
Laboratory Tests
Linearity
January
19,
1999, p.m.
Interrupted Sampling
January
19,
p.m-January 20, a.m
Interferences
January
20,
a.m.
Pressure Sensitivity
January
20,
a.m.
Ambient Temperature
January
20,
p.m.
Source Tests
Gas Rangetop January 21, a.m.
Gas Water Heater January 21, a.m.
Diesel Generator High RPM January 21, a.m.
Diesel Generator-Idle January 21, p.m.
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To assess inter-unit variability, two identical Horiba PG-250 analyzers were tested simul-
taneously. 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 Horiba 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 Horiba representative was supervised by Battelle
staff. Displayed NO and NOx 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 Horiba 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 Horiba 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
range; for the Horiba PG-250 analyzers, an NO range of 2,500 ppm and an N02 range of 500
ppm were used. These nominal ranges greatly 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® 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 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, gas standards of the
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>Vent to Hood
Coarse Needle Valves
Vent to Hood
Differential
P Gauge
Zero Gases
(N2 or Air)
Protocol 1
Standards
(NO or N02
Vacuum
Pump
Analyzer B
Analyzer A
Environics
2020 Diluter
Figure 3-1. Manifold Test Setup
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 Horiba 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. The actual
values of the span gases provided were 2,500 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 NOx concentrations were
recorded.
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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 1,700 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 (2,500 ppm NO and 350 ppm
N02), a second zero/span was conducted at 2,500 ppm NO and 50 ppm N02. The Horiba
analyzers were then 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 (2,500 ppm NO and 50 ppm N02) 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.
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
Horiba 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 NOx 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 + 381 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 3-2, 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;
9
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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 Horiba 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
appropriate zero gas, and an NO or N02 span gas of 1,700 ppm or 50 ppm, respectively, 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.
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 pro-
viding both analyzers with zero and span gases for NO and N02 (at the same values used in the
pressure test) at room, elevated, and reduced temperatures. A temperature range of 45 to 105°C
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 to be achieved using a conventional domestic refrigerator (Crosley
Model CT19A5W) with a refrigerator volume of 13.1 ft3. However, the large thermal mass and
internal heat sources of the Horiba analyzers prevented proper cooling in the refrigerator. Instead
the analyzers and manifold were placed outside the window of the laboratory, where the outdoor
ambient temperature of 45 °F provided the proper conditions.
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 outside location. 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 1 hour stabilization period, the zero and span checks were
repeated a final time.
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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 8KBtu/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. These were available 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 3
to 6 ppm. NOx emissions dropped as the water temperature rose after ignition, stabilizing at the
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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.
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3.3.2.1 Sampling Systems
As much as possible, common vendor and reference sampling systems were used throughout
combustion source testing. The sampling systems consisted of probes and sample-transfer lines.
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 two Horiba analyzers sampled from the same probe used by the reference analyzers, by means
of a "tee" fitting at the downstream end of that probe. 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 (32°F). The reference particulate-removal system consisted of a 47-millimeter in-line quartz
filter. The Horiba analyzers each used an in-line particle filter in sampling from the diesel source.
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
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that of the NO calibration determined the N02 conversion efficiency. For the Horiba source tests,
which took place on January 21, 1999, calibration data from the afternoon of January 20 were
applied. Conversion efficiency values of 88.1 percent and 88.3 percent were found for the Model
14A and Model 10 monitors, respectively, and all reference data were corrected for those
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.
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
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
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the N0X 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
Horiba operator indicated when he was ready to take the first set of readings (a set of readings
consisting of the NO and NOx 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. The Horiba analyzers were unable to
obtain simultaneous NO and NOx readings every minute, so NO readings were obtained on every
odd minute, and NOx readings on every even minute, for both analyzers. Thus the extended
sampling data consist of 30 NO and 30 NOx readings for each Horiba analyzer.
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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 chemiluminescence reference analyzer data
with the quality requirements of Method 7E. The results of this assessment are shown in Table 4-
1. The purpose of validating reference data was to ensure usability for the purposes of comparison
with the demonstration technologies. 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.
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Table 4-1. Results of QC Procedures for Reference NOx Analyzers for Testing for
Horiba PG-250 Analyzers
N02 to N conversion
efficiency
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
Span drift
Meets criteria
88.1% for Model 14A in 100
ppm and 1,000 ppm ranges
88.3% for Model 10 in 100 ppm
and 1,000 ppm ranges
Meets criteria
(r2 = 0.9994)
Meets criteria
(r2 = 0.9994)
Meet ± 2% requirement (relative
to span)
Model 10
Model 14A
NO NO
Error, % of Error, % of
Span % of Scale Span % of Scale
0.8% 30%
<0.1% 60%
no2
0.7% 30%
0.2% 60%
no2
Error, % of
Error, % of
Span
% of Scale Span % of Scale
2.0%
30% 1.9% 30%
0.2%
60% 0.1% 60%
Meets ± 3% requirement
(relative to span)
Rangetop Test
Unit 10
> ± 3% on NO span (see text)
Rangetop Test
Unit 14A
< ± 3%
Water Heater Test
Unit 10
< ± 3%
Water Heater Test
Unit 14A
> ± 3% on NO span (see text)
Diesel Engine Test (High RPM)
Unit 10
< ± 3%
Diesel Engine Test (High RPM)
Unit 14A
< ± 3%
Diesel Engine Test (Low RPM)
Unit 10
< ± 3%
Diesel Engine Test (Low RPM)
Unit 14A
< ± 3%
Interference check
< ± 7%
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5. A different diesel generator was used than that originally planned.
6. An oxygen sensor was not used during source tests.
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 previous Battelle experience in
sampling the combustion sources used in this test and other similar sources.
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
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# Nitrogen Acid Rain CEM Zero
# Acid Rain CEM Zero Air
# Battelle-Prepared Organics Mixture.
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. 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. 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
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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. Leakage was eliminated in all subsequent
tests—no impact on Horiba test.
Added start and stop time to data sheets as a method
to document equilibration.
All source tests with the Horiba 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 Horiba test.
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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.
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.
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
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that were used to assess the four-point calibration of the reference method were also verified to be
correct.
Review of vendor and reference method data sheets revealed the following discrepancies for
relative accuracy test 1/21/99, which may have an impact on data quality for the Horiba tests:
1. Using water heater, NO span drift >3 percent on Model 14A reference analyzer
2. Using gas rangetop NO span drift >3 percent on Model 10 reference analyzer.
These two items are noted in Table 4-1, which summarizes the reference method data quality for
the Horiba verification test. The span drift noted in these two instances slightly 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 two drift values noted in Table 4-1 are within
this allowable drift criterion, and no adverse impact on the Horiba 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.
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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
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 analyzer does
not affect the Horiba data since calibration was performed before combustion source testing with
the Horiba 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 Horiba 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 +
(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 (Y ) = (4)
a j
A test for departure from linearity was carried out by comparing the residual mean square
1 6 ~
7£ <7C " " aicifncwc. (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
t=i j=i
(Xc
a.J
-a,
~aic)2
w . =
E E
j=i
(Y - Y )2 w + (7 -a„ -a,c)
^ 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 = 3
-------
SE (LOD) a LOD —-—
\ 2(«-l)
+
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:
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:
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:
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
the actual concentration of the interferant. For example, an analyzer that measures NO is
Total Response = Rc - Rz
Response950/o = 0.95(Total Response) + Rz.
RT = Time950/o - Time,,
26
-------
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 = p / (0.040825ct(c)) for the zero concentration test
t = p / (0.0707 1
-------
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:
ik
Jn (7)
V v ifirw. v '
_ v
JI ^ d
d\ + tn-i —
RA = = V— x 100%
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 ^ , 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
S
SE *
yfnx ^
0.3634 - (Cr)2 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
28
-------
values adjusts for variation in the source output. The slope and the standard error of the slope are
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 per-
formance 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 defection 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 and b list the data obtained in the linearity tests for NO and N02, respectively. The
response as both NO and NOx from each Horiba analyzer is shown in those tables.
Table 6-2 shows the results of the linear calibration curve fits for each unit and each analyte,
based on the data shown in Tables 6-la and b.
Table 6-la. Data from NO Linearity Test of Horiba PG-250 Analyzers
Actual NO
Unit A NO
Unit A NOx
Unit B NO
Unit B NOx
Reading
(ppm)
(ppm)
(ppm)
(ppm)
(ppm)
1
0.0
4
3
7
6
2
2510.7
2508
2501
2512
2511
3
240.5
236
249
233
244
4
1004.3
985
991
986
993
5
0.0
4
6
1
2
6
1703.3
1685
1684
7
501.9
499
497
497
494
8
240.5
238
241
235
238
9
0.0
5
9
3
5
10
501.0
490
492
488
491
11
1004.3
990
987
991
987
12
1703.3
1687
1686
1686
1689
13
0.0
4
5
1
2
14
2506.7
2486
2493
2487
2489
15
1703.3
1690
1688
1691
1693
16
1003.1
995
995
995
993
17
0.0
7
8
4
4
18
500.4
492
494
491
493
19
240.0
237
239
236
237
20
2506.7
2490
2484
2491
2492
21
0.0
9
9
5
9
30
-------
Table 6-lb. Data from N02 Linearity Test of Horiba PG-250 Analyzers
Actual N02
Unit A NO
Unit A NOx
Unit B NO
Unit B NO
Number
(ppm)
(ppm)
(ppm)
(ppm)
(ppm)
1
0.0
8
7
4
4
2
493.2
9
348
5
355
3
58.6
3
57
0
50
4
250.0
4
186
1
188
5
0.0
3
14
0
8
6
340.5
253
256
7
129.3
3
110
0
106
8
58.6
3
48
0
52
9
0.0
3
9
0
5
10
129.3
3
97
0
97
11
250.0
4
188
1
186
12
340.5
5
256
2
258
13
0.0
3
13
0
7
14
493.2
6
351
3
354
15
340.5
4
260
1
266
16
250.0
4
200
1
194
17
0.0
3
8
0
4
18
129.3
0
94
3
95
19
58.6
3
47
0
44
20
493.2
6
362
2
358
21
0.0
3
16
0
9
Table 6-2. Statistical Results for Test of Linearity
Unit A Unit B
Linear Regression NO N02 NO N02
Intercept (ppm) (Std 3.602 (1.311) 11.106(1.315) 1.142 (1.325) 6.456 (0.975)
Err)
Slope (Std Err) 0.990 (0.002) 0.705 (0.008) 0.991 (0.002) 0.722 (0.006)
R2 0.9999 0.9977 0.9999 0.9987
The results shown in Tables 6-1 and 6-2 confirm that the Horiba PG-250 analyzers provide linear
response to NO over a wide operating range. The slopes and regression coefficients for NO data
from both Units A and B compare well with the requirements for linearity generally expected of
these analyzers, as stated in the SCAQMD test protocol.(8) The regression slopes shown in
Table 6-2 for NO are both 0.99, and thus are well within the expected range of 0.98 to 1.02.(8)
31
-------
Similarly, the squared regression coefficient values (R2) for NO both exceed the expected
minimum value of 0.999.(8) The NO regression results shown in Table 6-2 are for NO response in
the NO mode of the PG-250 analyzers; essentially the same linear performance (slope > 0.99 and
R2 > 0.9999) was also observed for the NOx response of both analyzers when sampling NO (see
Table 6-la).
In contrast, Tables 6-lb and 6-2 show approximately linear but non-quantitative behavior of the
PG-250 analyzers in response to N02. At all N02 levels, the PG-250 analyzers read considerably
lower than the actual N02 levels provided; the slope of response to N02 was only about 0.7 on
both analyzers. Although the R2 values indicate a high degree of correlation, the low slopes
indicate relatively poor accuracy in responding to N02. This result is thought to be caused by the
inability of the N02 converters in the Horiba analyzers to completely reduce the N02 provided in
the linearity test. The Horiba manual indicates that the PG-250 is applicable for N02 only at levels
of 6 ppm or less, and that the lifetime of the converter will be substantially shortened by sampling
of N02 above 6 ppm. Table 6-2 indicates that conversion efficiency, as well as lifetime, is a
concern. Even for very short periods of time, the PG-250 converters appear to give incomplete
conversion of N02 to NO at levels between 50 and 500 ppm.
In actual source sampling, a correction could be applied for the incomplete N02 conversion
indicated by Table 6-2. The results in Tables 6-lb and 6-2 indicate that the conversion efficiency
is reasonably constant over the range of N02 tested. However, the efficiency might approach
100 percent at lower N02 levels. As a result, it would be necessary to determine the efficiency as
a function of concentration in order to apply a correction with confidence, or to determine the
efficiency at the N02 levels characteristic of a particular source before applying a correction. The
manufacturer's warning about converter lifetime also indicates that the stability of N02 conversion
efficiency over time is a concern, possibly requiring frequent efficiency checks to maintain
accurate N02 measurements even at low concentrations.
6.1.2 Detection Limit
Table 6-3 shows the estimated detection limits for each Horiba unit for both NO and N02,
determined from the data obtained in the linearity test.
Table 6-3. Estimated Detection Limits for Horiba PG-250 Analyzers
Unit A
Unit B
NO
no2
NO
no2
Estimated Detection Limit (ppm)
6.284
15.554
7.103
8.881
(Standard Error) (ppm)
(1.987)
(4.921)
(2.246)
(2.809)
Table 6-3 displays the estimated detection limits, and their standard errors for NO and N02,
separately for each Horiba analyzer. For each unit, the detection limit for NO is approximately
6-7 ppm. N02 detection limits are about 9 and 16 ppm, respectively. It must be noted that these
32
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detection limits were obtained on ranges of 0 to 2,500 ppm and 0 to 500 ppm, for the NO and
N02 tests, respectively. Lower detection limits can be obtained by use of lower detection ranges,
as demonstrated in the combustion source tests (Section 6.2).
6.1.3 Response Time
Table 6-4 lists the data obtained in the response time test of the Horiba PG-250 analyzers.
Table 6-5 shows the response times of the analyzers to a step change in analyte concentration,
based on the data shown in Table 6-4.
Table 6-5 shows that the Horiba PG-250 analyzers provide substantially faster responses for NO
than for N02, and that the two analyzers were similar in their response to both species. Time
response for NO was 40 seconds on both analyzers. The N02 time response was 90 seconds on
Unit A, but substantially longer, 131 seconds, on Unit B. The reason for this difference is not
known. These response times are well within the 4-minute time response criterion generally
required of portable NO/N02 analyzers.(8)
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 concentra-
tions of 2,500 ppm NO and 50 ppm N02 were used for this test. The latter value was chosen
based on the observations of the N02 linearity test, discussed above. Table 6-7 shows that zero
drift values were all less than 8 ppm, and somewhat smaller for N02 than for NO, perhaps due to
the much lower N02 span concentration used relative to that for NO. Span drift values for N02
were small in an absolute sense (6 and 9 ppm) but amounted to 12 and 18 percent, respectively, of
the 50 ppm span value. Before the shutdown the PG-250 analyzers indicated only about 70
percent of the 50 ppm span; after shutdown response was about 55 percent of the span. These
results further indicate the inability of the PG-250 analyzers to completely convert N02 for
detection.
NO span drift values in Table 6-7 are 69 and 33 ppm, amounting to 2.8 and 1.3 percent,
respectively, of the 2,500 ppm span value.
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. The extent of interference is
shown in Table 6-9 both as a ppm difference relative to the preceding zero reading, and as the
apparent relative sensitivity to the interferant, as a percentage of the sensitivity to NO.
33
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Table 6-4. Response Time Data for Horiba PG-250 Analyzers
Unit A NO
Unit A N02
Unit B NO
Unit B N02
Time (sec)
(ppm)
(ppm)
(ppm)
(ppm)
0
3
6
0
11
10
3
6
1
11
20
25
6
15
11
30
912
127
1088
89
40
1597
215
1618
194
50
1650
227
1655
211
60
1666
234
1659
219
70
1665
236
1670
224
80
1667
238
1673
227
90
1668
240
1675
230
100
1671
242
1676
232
110
1672
243
1677
234
120
1673
245
1678
236
130
1674
245
1679
237
140
1675
246
1680
238
150
1676
247
1680
239
160
1676
248
1681
240
170
1677
249
1681
241
180
1678
249
1682
242
190
1678
249
1682
242
200
1679
250
1682
243
210
1679
250
1682
244
220
1680
250
1682
244
230
1680
251
1682
245
240
1681
251
1683
246
250
1680
251
1683
246
260
1681
252
1683
247
270
1681
253
1683
247
280
1681
252
1684
248
290
1682
252
1684
248
300
1682
253
1684
249
34
-------
Table 6-5. Response Time Results for Horiba PG-250 Analyzers
Unit A
Unit B
NO
no2
NO
no2
Response Time* (sec)
40
93
40
131
* 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.
Table 6-6. Data from Interrupted Sampling Test with Horiba PG-250 Analyzers
Unit A NO
Unit A NOx
Unit B NO
Unit B NOx
Pre-Shutdown Date:
1/19/99
Time:
18:53
Pre-Shutdown Zero (ppm):
9
7
5
3
Pre-Shutdown Span (ppm):
2490
35
2491
36
Post-Shutdown Date:
1/20/99
Time:
09:20
Post-Shutdown Zero (ppm):
2
3
-1
0
Post-Shutdown Span (ppm):
2421
29
2458
27
Table 6-7. Pre- to Post-Test Differences as a Result of Interruption of Operation of Horiba
PG-250 Analyzers
Unit A
Unit B
Pre-Shutdown—Post-Shutdown
NO
NOx
NO
NOx
Zero Difference (ppm)
7
4
6
3
Span Difference (ppm)
69
6
33
9
35
-------
Table 6-8. Data from Interference Tests on Horiba PG-250 Analyzers
Interferant
Interferant, Cone.
Response (ppm)
Gas
(ppm)
Unit A NO
Unit A NOx
Unit B NO
Unit B NOx
Zero
0
0
0
1
CO
496 ppm
0
1
0
1
Zero
0
0
0
0
o
o
N)
5.03%
-1
0
-1
0
Zero
-1
0
-1
0
nh3
494 ppm
-1
0
0
0
Zero
-1
0
-1
0
HCs
590 ppm
-1
-1
-1
0
Zero
-1
-1
-1
0
S02
501 ppm
-1
0
-1
0
Zero
-1
-1
-1
0
SO, + NO
451+381 ppm
330
329
333
332
Table 6-9. Results of Interference Tests of Horiba PG-250 Analyzers
Unit A Response, ppm Unit B Response, ppm
(relative sensitivity, %) (relative sensitivity, %)
Interferent NO NOx NO NOx
CO (496 ppm)
0
1 (0.2%)
0
0
C02 (5.03%)
-1
0
-1
0
NH3 (494 ppm)
0
0
1
0
HCs (590 ppm)
0
-1 (-0.2%)
0
0
S02 (501 ppm)
0
1 (0.2%)
0
0
S02 (451 ppm) +
-51
-52
-48
-49
NO (381 ppm)
(-11.3%)
(-11.5%)
(-10.6%)
(-10.9%)
The results in Table 6-9 indicate no significant interference from any of the individual interferants.
Differences between the individual interferants and the preceding zero gases were all ±1 ppm or
less. This is within the variability of the zero gas responses themselves, and indicates no real
response to the interferants. The only indication of an interference is the response to NO in the
presence of S02; Table 6-9 shows that the PG-250 analyzers indicated about 330 ppm NO, about
13 percent lower than the concentration provided. Reckoned as a relative interference from S02,
this effect equates to an 11 to 12 percent negative interference from the 451 ppm S02 present
(e.g.,-51/451 = -11.3%).
36
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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 Horiba PG-250 analyzer.
Changes in zero readings were 2 ppm or less. NO span changes were 5 to 18 ppm, equal to 1 per-
cent or less of the NO span value. N02 span changes were very small, but the response to the N02
span gas was only about half of its 50 ppm value. It is noteworthy that no consistent trend of
pressure dependence is indicated by the results in Table 6-11. For example, all of the NO span
readings at both +10 and -10 inches of water duct pressure are greater than those at ambient
pressure, suggesting (if the changes were significant) that an increase in response occurs both with
increased and with decreased pressure. This implication is contrary to the physical principles
governing the response of the analyzers, and further indicates that no substantial pressure
dependence exists over the range of pressures tested.
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. Surprisingly, sample flow rates at -10 inches of
water exceeded those at ambient pressure by 1 to 2 percent; flow rates at +10 inches of water
were reduced by almost 3 percent.
37
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Table 6-10. Data from Pressure Sensitivity Test for Horiba PG-250 Analyzers
Pressure
Unit A NO Unit A NO, Unit B NO Unit B NO,
Ambient
+10 in. H90
-10 in. H20
Flow rate (ccm)
421
421
445
445
Zero (ppm)
-1
-1
0
0
NO span (ppm)
1648
1646
1656
1653
Zero (ppm)
4
3
3
3
N02 span (ppm)
6
25
6
24
Zero (ppm)
0
1
0
1
Flow rate (ccm)
409
409
433
433
Zero (ppm)
2
2
2
2
NO span (ppm)
1653
1649
1663
1663
Zero (ppm)
4
6
4
4
N02 span (ppm)
0
23
0
24
Zero (ppm)
-1
0
-1
-1
Flow rate (ccm)
431
431
450
450
Zero (ppm)
3
3
2
2
NO span (ppm)
1661
1658
1674
1672
Zero (ppm)
6
5
5
4
N02 span (ppm)
0
24
0
24
Zero (ppm)
-1
1
0
1
Table 6-11. Pressure Sensitivity Results for Horiba PG-250 Analyzers
Unit A Unit B
NO
no2
NO
no2
Zero
High-Ambient (ppm cliff*)
0.67
1.67
0.67
0.33
Low-Ambient (ppm diff)
1.67
2
1.33
1
Significant Pressure Effect
N
N
N
N
Span
High-Ambient (ppm diff)
5
-2
7
0
Low-Ambient (ppm diff)
13
-1
18
0
Significant Pressure Effect
N
N
N
N
Flow
High-Ambient (ccm diff*)
-12
-12
Rate
Low-Ambient (ccm diff)
10
5
* ppm or ccm difference between high/low and ambient pressures. The zero differences were calculated based
on the average of the zero check responses.
38
-------
6.1.7 Ambient Temperature
Table 6-12 lists the data obtained in the ambient temperature test with the Horiba PG-250
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 1,700 ppm for NO and
50 ppm for N02.
Response of the analyzers tended to decrease with elevated temperature and increase with
reduced temperature. No statistically significant differences in zero readings with temperature
were found. However, statistically significant differences in span readings (using 1,700 ppm NO
and 50 ppm N02) were found for NO for both units, but not for N02. Relative to the room
temperature results, the differences in NO span response amount to 4.5 to 5.0 percent of the
1,700 ppm span value at elevated temperature, and 6.1 to 6.7 percent of the span value at reduced
temperature. This extent of temperature dependence is likely to be important and must be
Table 6-12. Data from Ambient Temperature Test of Horiba PG-250 Analyzers
Unit A NO
Unit A N02
Unit B NO
Unit B N02
Condition
(ppm)
(ppm)
(ppm)
(ppm)
(Room Temp.)
Temp. 28.3°C (83°F)
Zero
-1
0
-1
0
NO span
1653
1649
1659
1659
Zero
-1
1
0
1
N02 span
0
23
0
24
(Heated)
Temp. 41.1oC(106°F)
Zero
0
0
-2
-2
NO span
1553
1558
1558
1567
Zero
5
5
2
2
N02 span
4
26
2
25
(Cooled)
Temp. 8.3°C (47°F)
Zero
-2
-2
2
2
NO span
1733
1712
1758
1748
Zero
-2
-2
2
2
N02 span
-2
20
2
25
(Room Temp.)
Temp. 26.1°C (79°F)
Zero
-1
-1
-1
0
NO span
1605
1603
1628
1630
Zero
3
3
3
3
N02 span
1
24
2
25
39
-------
Table 6-13. Ambient Temperature Effects on Horiba PG-250 Analyzers
Unit A
NO
no2
Unit B
NO
no2
Zero
Heat - room (ppm diff*)
2.5
1.75
-0.25
-1
Cool - room (ppm diff)
-2
-2.75
1.75
1
Significant Temp. Effect
N
N
N
N
Span
Heat - room (ppm diff)
-76
2.5
-85.5
0.5
Cool - room (ppm diff)
104
-3.5
114.5
0.5
Significant Temp. Effect
Y
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.
recognized in actual use. No significant temperature dependence in N02 spans could be detected;
however, the very low N02 readings (about half of the 50 ppm value provided) make it difficult to
detect any differences.
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. The results in Table 6-15 are similar to
those found in the interrupted sampling test (Table 6-7). Zero drift was 6 ppm or less for both NO
and N02 on both analyzers in the linearity test, and was 2 ppm or less in the ambient temperature
test. The lower zero drift values in the temperature test may be due in part to the lower
concentrations of NO and particularly N02 to which the analyzers were exposed in that test. On
the other hand, NO span drift was greater in the ambient temperature test than in the linearity test.
NO span drift amounted to less than 1 percent of the 2,500 ppm span used in the linearity test, but
1.8 to 2.8 percent of the 1,700 ppm span used in the temperature test. This behavior may be a
consequence of the temperature dependence found in that test, as described in section 6.1.7. N02
span drift amounted to 0.6 to 2.8 percent of the 493.2 ppm span in the linearity test, and to about
2 percent of the 50 ppm span used in the temperature test. Comparison of these results is
confounded by the widely different span concentrations used. Note that the PG-250 analyzers
consistently read low on both N02 span concentrations.
40
-------
Table 6-14. Data from Linearity and Ambient Temperature Tests Used to Assess Zero and
Span Drift of the Horiba PG-250 Analyzers
Unit A NO
Unit A N02
Unit B NO
Unit B N02
Test
(ppm)
(ppm)
(ppm)
(ppm)
Linearity Pre-Test Zero
4
3
7
6
Pre-Test Span
2508
348
2512
355
Post-Test Zero
9
9
5
9
Post-Test Span
2490
362
2491
358
Ambient Temperature Pre-Test Zero
-1
1
-1
1
Pre-Test Span
1653
23
1659
24
Post-Test Zero
-1
3
-1
3
Post-Test Span
1605
24
1628
25
Table 6-15. Zero and Span Drift Results for the Horiba PG-250 Analyzers
Unit A
Unit B
NO
no2
NO
no2
Pre- and Post-Differences
(ppm)
(ppm)
(ppm)
(ppm)
Linearity Test Zero
-5
-6
2
-3
Span
18
-14
21
-3
Ambient Temperature Test Zero*
0
-2
0
-2
Span
48
-1
31
-1
* Drift is the difference (pre-monitoring minus post-monitoring) between the first and last zero check
response averages at room temperature.
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. 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 sampling 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.
41
-------
Table 6-16a. Data from the Gas Rangetop in Verification Testing of Horiba PG-250 Analyzers
Horiba Analyzer Data
Reference Analyzer Data
Unit A NO
Unit A N02
Unit A NOs
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
5.17
1.29
6.46
5.14
1.26
6.4
5.1
1.5
6.6
5.1
1.8
7.0
2
5.65
1.39
7.04
5.58
1.45
7.03
5.5
1.8
7.4
5.6
2.1
7.7
3
5.73
1.26
6.99
5.77
1.28
7.05
5.8
1.9
7.7
5.9
1.8
7.8
4
6.09
1.09
7.18
6.08
1.09
7.17
5.8
1.9
7.6
6.0
1.9
8.0
5
5.87
1.72
7.59
5.97
1.59
7.56
5.9
1.8
7.7
6.1
1.8
7.9
6
6.1
1.29
7.39
6.14
1.21
7.35
5.9
1.9
7.9
6.0
2.1
8.1
7
5.82
1.64
7.46
5.84
1.6
7.44
6.0
1.8
7.8
6.0
2.1
8.1
8
6.07
1.29
7.36
6.08
1.39
7.47
5.9
1.9
7.8
6.1
1.8
7.9
9
5.95
1.27
7.22
5.98
1.36
7.34
5.9
1.9
7.8
6.0
1.9
8.0
NJ
Table 6-16b. Data from Gas Water Heater in Verification Testing of Horiba PG-250 Analyzers
Horiba Analyzer Data
Reference Analyzer Data
Unit A NO
Unit A N02
Unit A NOs
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
63.4
4.4
67.8
63.4
3.4
66.8
59.6
4.4
63.9
60.8
3.6
64.4
2
62.8
2.3
65.1
62.6
2.6
65.2
58.5
4.4
62.8
59.8
4.6
64.4
3
62.1
3.9
66
62
4
66
58.2
4.3
62.4
59.7
4.4
64.1
4
60.7
4.4
65.1
60.7
4.5
65.2
56.8
5.8
62.6
58.9
5.3
64.2
5
60.1
5.1
65.2
60.1
5.1
65.2
57.2
3.9
61.1
59.0
3.7
62.8
6
60.1
4.1
64.2
60.2
4.1
64.3
56.4
5.6
62.0
58.2
5.2
63.4
7
60.5
2.6
63.1
60.5
2.6
63.1
55.6
5.7
61.2
57.8
5.0
62.8
8
58.4
4.6
63
59.4
3.6
63
55.6
5.4
60.9
57.8
4.3
62.1
9
59
4.4
63.4
59
4.4
63.4
55.2
4.2
59.4
57.3
3.5
60.8
-------
Table 6-16c. Data from the Diesel Generator at High RPM in Verification Testing of Horiba PG-250 Analyzers
Unit A NO
(ppm)
Unit A N02
(ppm)
Horiba Analyzer Data
Unit A NOs 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)
iono2
(ppm)
10 NOx
(ppm)
1
80.2
31.6
111.8
80.4
37.4
117.8
74.5
68.6
143.1
75.5
70.5
146.0
2
73.8
29.2
103
74.7
35.2
109.9
67.4
57.1
124.5
68.9
60.9
129.8
3
72.1
33.2
105.3
72.9
39.2
112.1
70.2
53.1
123.3
71.7
56.6
128.3
4
79.4
32.1
111.5
80.3
36.2
116.5
72.3
56.1
128.4
74.5
58.8
133.3
5
76.6
32
108.6
78.2
38.2
116.4
73.4
53.6
127.0
75.5
56.6
132.1
6
76.1
30.9
107
76
34.9
110.9
70.6
53.3
124.0
74.5
53.4
127.9
7
75.3
34.3
109.6
76.9
36.4
113.3
70.2
53.6
123.8
72.6
55.6
128.2
8
74.8
33.8
108.6
75.5
37.9
113.4
69.7
56.4
126.1
71.7
58.8
130.5
9
77.1
35.1
112.2
77.5
36.9
114.4
70.6
54.8
125.4
72.6
56.6
129.3
Table 6-16d. Data from Diesel Generator at Idle in Verification Testing of Horiba PG-250 Analyzers
Horiba Analyzer Data
Reference Analyzer Data
Unit A NO
Unit A N02
Unit A NOs
Unit B NO
Unit B N02
Unit B NOx
14ANO
14A NO,
14A NOs
10 NO
iono2
10 NOx
(ppm)
(ppm)
(ppm)
(ppm)
(ppm)
(ppm)
(ppm)
(ppm)
(ppm)
(ppm)
(ppm)
(ppm)
1
302.9
71.4
374.3
304.2
75.7
379.9
279.9
125.4
405.3
284.9
123.9
408.8
2
307.8
66.4
374.2
308.3
72.3
380.6
286.1
118.3
404.4
288.7
116.5
405.1
3
306.4
66.6
373
306.7
71.7
378.4
284.2
120.4
404.7
285.9
120.7
406.6
4
306.4
75.9
382.3
306.4
80.6
387
285.2
124.8
410.0
288.7
122.9
411.5
5
310.6
73.6
384.2
310.6
77.4
388
290.4
120.0
410.4
293.4
116.5
409.9
6
309.6
67.9
377.5
309.1
71.6
380.7
289.0
118.3
407.3
288.7
118.6
407.3
7
310.1
70.4
380.5
310
74.6
384.6
286.4
122.3
408.7
286.8
119.7
406.5
8
306.5
75.2
381.7
306.1
79.4
385.5
286.8
124.1
410.9
284.9
123.9
408.8
9
279.7
78.5
358.2
280.5
84.8
365.3
262.4
130.0
392.4
259.4
126.1
385.5
-------
Table 6-17. Relative Accuracy of Horiba PG-250 Analyzers
Unit A
Unit B
NO
no2
NOx
NO
no2
NOx
Source
(%)
(%)
(%)
(%)
(%)
(%)
Gas Rangetop
1.85*
37.01
8.21
1.85
35.83
7.76
(6 ppm NO, 2 ppm N02)***
(0.63)**
(3.33)
(0.54)
(0.54)
(2.88)
(0.44)
Gas Water Heater
5.90
35.69
4.79
5.81
37.59
4.47
(60 ppm NO, 5 ppm N02)
(0.33)
(7.86)
(0.44)
(0.25)
(7.24)
(0.37)
Diesel Generator-High RPM
7.48
51.06
19.18
8.50
42.38
14.69
(70 ppm NO, 60 ppm N02)
(0.64)
(2.73)
(1.11)
(0.61)
(2.40)
(0.94)
Diesel Generator-Idle
7.60
42.85
7.73
7.67
38.94
6.43
(280 ppm NO, 120 ppm N02)
(0.14)
(0.64)
(0.16)
(0.14)
(0.62)
(0.13)
*Percent relative acuracy calculated using equation 7.
**Standard error of the relative accuracy results, estimated according to equation 8.
***Approximate NO and N02 levels from each sourceare shown; see Tables 6-16a through d.
Table 6-17 shows that both PG-250 analyzers provided very good relative accuracy for NO with
all combustion sources; relative accuracy for NO ranged from 1.85 to 8.5 percent over both
analyzers and all sources. Interestingly, accuracy for NO was best at the lowest NO levels (i.e.,
from the gas rangetop). This may be due to the use of different measurement ranges on the PG-
250 analyzers that allowed the operator to match the range to the source output concentration.
In contrast to the case for NO, accuracy for N02 was relatively poor with all sources, always
exceeding 35 percent. This finding is attributed to the limited capacity of the N02 converters in
the PG-250 analyzers, which results in incomplete reduction of N02 to NO. Accuracy for N02 is
relatively poor even for the low N02 levels emitted by the gas rangetop and water heater, which
are within the 6 ppm level recommended by the manufacturer for use of the PG-250. Similarly,
poor N02 accuracy was observed with zero and span gases, as described in Section 6.2.2.
As a result of the poor N02 accuracy, NOx relative accuracy is usually not as good as that for NO.
However, all NOx relative accuracy values are below 20 percent, and all but two are below
10 percent. It must be noted that the relative accuracy achievable for NOx with the PG-250
analyzers will depend on the relative proportions of NO and N02 in the sample gas. NOx relative
accuracy will be best when the ratio of NO to N02 is high.
In all combustion tests, the PG-250 analyzers exhibited excellent unit-to-unit agreement. For
example, the average NO values determined by the two Horiba analyzers in the four source tests
showed agreement ranging from 0.1 to 1.0 percent, and agreed more closely than did the corre-
sponding results from the two reference analyzers. For NOx, the unit-to-unit agreement of the two
Horiba analyzers ranged from 0.1 to 4.8 percent; and, in two of the source tests, the unit-to-unit
agreement of the Horiba analyzers was better than that of the reference analyzers. These results
44
-------
indicate a high degree of consistency in the performance of the PG-250 analyzers on combustion
sources.
6.2.2 Zero and Span Drift
Table 6-18 shows the data used to evaluate zero and span drift of the Horiba PG-250 analyzers
from the combustion source tests. The span values provided differed from one combustion source
to the next, as shown in Table 3-3.
Table 6-18. Data Used to Assess Zero and Span Drift for Horiba PG-250 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
-0.04
0.14
-0.06
0.14
Pre-Test Span
20.08
7.43
20.07
7.47
Post-Test Zero
0
0.09
0.04
0.05
Post-Test Span
19.96
7.5
20.02
7.55
Gas Water Heater**
Pre-Test Zero
0.5
0.6
0.4
0.5
Pre-Test Span
100
10.5
100
10.4
Post-Test Zero
0.3
0.5
0.2
0.5
Post-Test Span
98.5
8.4
98.8
8.6
Diesel-High RPM***
Pre-Test Zero
0.6
0.6
0.4
0.5
Pre-Test Span
200
26.2
199.9
31.6
Post-Test Zero
0.6
1.8
0.5
1.3
Post-Test Span
197.5
32.6
198
35
Diesel-Idle****
Pre-Test Zero
0
1.6
0
1.2
Pre-Test Span
400
65.5
400
70.2
Post-Test Zero
1.3
3.3
0.9
2.7
Post-Test Span
402.9
70.7
403.1
73
*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
45
-------
Table 6-19 summarizes the zero and span drift observed in the combustion source tests. Zero drift
was always within 2 ppm. Span drift was somewhat larger, and was greater for N02 than for NO
in most cases. Both zero and span drift values increased in progressing from low- to high-NOx
sources. The span drift values for NO in Table 6-19 are generally equivalent to 1 percent or less
of the span values provided in the various source tests (see Table 3-3). However, the N02 span
drift values in Table 6-19 are more variable, ranging to 10 percent or more of the N02 span values
provided (Table 3-3). At all N02 span levels, the PG-250 analyzers read considerably low on the
span gases.
Table 6-19. Results of Zero and Span Drift Evaluation for Horiba PG-250 Analyzers
Unit A
Unit B
Pre-Test—
NO
no2
NO
no2
Post-Test
(ppm)
(ppm)
(ppm)
(ppm)
Gas Burner
Zero
-0.04
0.05
-0.1
0.09
Span
0.12
-0.07
0.05
-0.08
Gas Water Heater
Zero
0.2
0.1
0.2
0
Span
1.5
2.1
1.2
1.8
Diesel Generator-High RPM
Zero
0
-1.2
-0.1
-0.8
Span
2.5
-6.4
1.9
-3.4
Diesel Generator-Idle
Zero
-1.3
-1.7
-0.9
-1.5
Span
-2.9
-5.2
-3.1
-2.8
6.2.3 Measurement Stability
Table 6-20 shows the data obtained in the extended sampling test, in which the Horiba PG-250
and reference analyzers sampled diesel emissions at engine idle for a full hour without interruption
or sampling of ambient air. The Horiba 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 Horiba
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 and NOx data with time. Also shown in
Table 6-21 is an indication of whether the slopes indicated by the Horiba analyzers differed
from those observed by the reference analyzers.
Table 6-21 indicates that both the Horiba analyzers and the reference analyzers showed a gradual
decrease in NO and a smaller decrease in NOx during the 1-hour sampling period. For both NO
and NOx, there was a difference statistically between the trend shown by the two Horiba analyzers
and that shown by the reference analyzers. For both NO and NOx, the Horiba analyzers showed
larger trends than did the reference analyzers.
46
-------
Table 6-20. Data from Extended Sampling Test with Diesel Generator at Idle, Using Horiba PG-250 Analyzers
Unit A NO
(ppm)
Horiba Analyzer Data
Unit A NOs Unit B NO
(PPm) (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
309.4
308.8
285.2
124.3
409.4
284.9
125.0
409.9
2
377.4
388.2
285.2
129.7
414.9
284.0
125.0
409.0
3
307.8
307.9
288.0
130.8
418.8
288.7
123.9
412.6
4
383
386.6
289.2
125.2
414.3
288.7
126.1
414.8
5
304.2
303.2
285.9
124.5
410.4
284.0
127.1
411.1
6
382.1
386.2
287.3
121.9
409.2
285.9
125.0
410.9
7
302.6
303.6
284.9
125.7
410.6
283.0
128.2
411.2
8
380
385.3
284.2
126.4
410.7
283.0
129.3
412.3
9
302.8
303.6
285.8
126.9
412.6
284.9
128.2
413.1
10
382.1
387.2
285.2
127.5
412.7
284.0
129.3
413.2
11
298.8
299.3
283.4
126.3
409.7
281.1
126.1
407.2
12
374.8
380.6
282.3
127.5
409.8
283.0
126.1
409.1
13
298
300.4
281.9
127.0
408.8
280.2
129.3
409.5
14
374.8
379.2
279.5
126.4
405.9
276.4
130.3
406.8
15
295.8
297.3
280.4
127.5
407.9
279.2
129.3
408.5
16
377.9
383.3
283.3
126.4
409.7
280.2
130.3
410.5
17
297.8
297.2
280.4
129.7
410.1
279.2
129.3
408.5
18
374.2
381
283.0
124.6
407.6
281.1
131.4
412.5
19
295.6
297.2
281.4
126.4
407.8
279.2
129.3
408.5
20
375.4
383.5
280.4
126.4
406.8
277.4
132.5
409.8
21
293.5
295
278.5
131.8
410.3
277.4
132.5
409.8
22
380.1
387.6
282.3
129.7
412.0
281.1
131.4
412.5
23
298.5
297.8
282.3
128.6
410.9
280.2
130.3
410.5
24
378.3
384
285.2
124.3
409.4
283.0
127.1
410.2
25
298.4
298.7
283.3
128.6
411.9
281.1
130.3
411.5
26
379.7
385.6
282.3
128.6
410.9
280.2
130.3
410.5
27
294.4
296
280.4
129.7
410.1
279.2
130.3
409.6
28
373.4
379.2
281.4
126.4
407.8
279.2
127.1
406.4
29
297.5
298.7
285.2
125.3
410.5
280.2
128.2
408.4
30
375.4
381
278.5
127.5
406.0
276.4
130.3
406.8
-------
Table 6-20. Data from Extended Sampling Test with Diesel Generator at Idle, Using Horiba PG-250 Analyzers (continued)
Unit A NO
(ppm)
Horiba Analyzer Data
Unit A NOs Unit B NO
(PPm) (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
292.8
294.6
281.4
126.4
407.8
276.4
129.3
405.7
32
377.9
383.5
281.4
129.7
411.0
279.2
129.3
408.5
33
296
298
280.4
127.5
407.9
278.3
126.1
404.4
34
376.9
376.4
278.5
127.5
406.0
275.5
128.2
403.7
35
287.2
290.8
275.7
130.7
406.4
273.6
131.4
405.0
36
370.5
378.6
279.5
126.4
405.9
275.5
128.2
403.7
37
294.5
297.8
281.4
127.5
408.9
278.3
128.2
406.5
38
370.9
378.8
273.8
133.9
407.7
271.7
132.5
404.2
39
285.7
288.2
271.9
131.8
403.6
269.8
131.4
401.2
40
370.1
377
277.6
127.5
405.0
274.5
128.2
402.7
41
291.5
293.5
279.5
127.5
407.0
274.5
128.2
402.7
42
367.2
374.6
273.8
133.9
407.7
269.8
129.3
399.1
43
283
284.6
270.0
133.9
403.9
267.0
133.6
400.5
44
372.2
379.7
275.7
130.7
406.4
273.6
129.3
402.9
45
289
292.1
275.7
130.7
406.4
273.6
129.3
402.9
46
372.3
379.4
277.6
129.6
407.2
273.6
130.3
403.9
47
286.4
288.5
271.9
127.4
399.3
269.8
127.1
397.0
48
361.6
368.7
270.9
127.4
398.3
268.9
127.1
396.0
49
283
285.9
270.9
132.8
403.8
267.9
131.4
399.3
50
366.8
375.4
274.7
129.6
404.3
271.7
129.3
401.0
51
288.2
292.8
275.7
129.6
405.3
272.6
130.3
403.0
52
368.4
376.4
273.8
131.8
405.5
270.8
131.4
402.2
53
286.3
288.1
273.8
129.6
403.4
270.8
129.3
400.0
54
364.5
372.8
271.9
131.8
403.6
268.9
131.4
400.3
55
282.3
284
269.0
130.6
399.7
267.0
130.3
397.3
56
364.8
372.7
268.1
135.0
403.1
264.2
135.7
399.8
57
275.1
276.8
264.3
130.6
394.9
261.3
130.3
391.7
58
362.6
369.3
268.1
130.6
398.7
266.0
131.4
397.5
59
280.4
284.2
269.0
129.6
398.6
266.0
130.3
396.4
60
364
370.5
269.0
129.6
398.6
267.0
128.2
395.2
-------
It should be pointed out that, although statistically significant differences are shown in Table 6-21,
their practical significance is very small. For example, the reference analyzers indicate a
downward trend in NOx of -0.245 ppm/min, or -14.7 ppm per hour, whereas the two Horiba
analyzers indicate NOx trends of -0.308 ppm/min (-18.5 ppm/hr) and -0.273 ppm/min
(-16.4 ppm/hr). Considering that the diesel engine emitted approximately 400 ppm of NOx, these
slight differences in slope are negligible, amounting to a difference of no more than 4 ppm, or
about 1 percent of the source output, over 1 hour of sampling.
Table 6-21. Results of Evaluation of Measurement Stability for Horiba PG-250 Analyzer
Unit A
Unit B
Reference Units
NO
NOx
NO
NOx
NO
NOx
Slope
-0.439
-0.308
-0.384
-0.273
-0.323
-0.245
(Std Err)
(0.033)
(0.032)
(0.034)
(0.030)
(0.018)
(0.017)
Difference in Slopes
(ppm/min)
-0.114
-0.072
-0.059
-0.037
—
—
(Std Err)
(0.016)
*
(0.022)
*
(0.015)
*
(0.016)
*
* Statistically significant difference in slope among test unit and the averages of the reference units at the
5 percent significance level.
6.2.4 Inter- Unit Repeatability
The repeatability of test results between the two Horiba 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 Horiba PG-250 units at the 95 per-
cent confidence level. As Table 6-22 shows, significant differences between Units A and B were
found, primarily in relative accuracy, and these results indicate the variability from one analyzer to
another. However, it must be stressed that the statistical tests used to make this comparison are
extremely sensitive, and a distinction must be made between the statistical and the practical
significance of any differences.
For example, referring to the relative accuracy data in Table 6-17, it is clear that relatively minor
differences in performance may show up as statistically significant. For example, Units A and B
show relative accuracies of 7.5 and 8.5 percent, respectively, for NO from the diesel at high RPM.
Although statistically different, in a practical sense these results show that both Horiba analyzers
are equally applicable to this measurement. The important point is that the behavior of the two
Horiba PG-250 analyzers was essentially the same in nearly all verification tests.
49
-------
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.
Table 6-22. Summary of Repeatability
Unit A vs. Unit B
NO
no2
NOx
Linear Regression
Intercept
t-statistic
1.320
—
2.841
p-value*
0.216
—
0.018
Slope
t-statistic
-0.213
—
-1.709
p-value
0.835
—
0.118
Detection Limit
t-statistic
-0.273
—
1.177
p-value
0.787
...
0.248
Relative Accuracy
Gas Rangetop
t-statistic
0.898
0.043
0.603
p-value
0.395
0.967
0.563
Gas Water Heater
t-statistic
0.758
1.037
0.668
p-value
0.470
0.330
0.523
Generator-High
t-statistic
4.065
7.938
8.712
RPM
p-value
0.004
<0.001
<0.001
Generator-Idle
t-statistic
1.092
15.453
11.184
p-value
0.306
<0.001
<0.001
Measurement
Slope
t-statistic
-5.141
...
-1.691
Stability
p-value
<0.001
—
0.102
* p-value <0.05 indicates that two test units are statistically different at the 5 percent significance level.
6.3.1 Cost
The cost of each analyzer as tested in this verification test was approximately $25,000.
6.3.2 Data Completeness
The data completeness in the verification tests was 100 percent for both units of the Horiba PG-
250.
6.3.3 Maintenance/Operational Factors
The short duration of the verification tests prevented assessment of long-term maintenance costs,
durability, etc. However, the Horiba analyzers appear to be rugged and well-designed units. A
serious operational limitation is the N02 converter in the PG-250, which is designed to provide
50
-------
accurate measurements only at N02 levels below 6 ppm, but which, in fact, provided relatively
poor accuracy for N02 at all levels tested.. This limitation may prevent accurate N02 and NOx
measurements with any source that emits significant N02 concentrations.
51
-------
Chapter 7
Performance Summary
The Horiba PG-250 analyzers provided linear response to NO over the full 2,500 ppm range
tested. Response to N02 was approximately linear but exhibited a slope much less than one (i.e.,
about 0.7) on both analyzers. This behavior is attributed to the limited capacity of the N02 con-
verters in the analyzers, which cannot completely convert N02 to NO. For analyzers A and B,
respectively, detection limits determined from the linearity test data were 6 and 7 ppm on the
0 to 2,500 ppm range for NO, and 16 and 9 ppm on the 0 to 500 ppm range for N02. Lower
detection limits can be achieved using lower measurement ranges, as was evident in the com-
bustion source tests. Response times of both analyzers for NO were 40 seconds; for N02 analyzer
A had a response time of about 90 seconds and analyzer B had a response time of 130 seconds.
Zero drift during laboratory tests was 6 ppm or less. Span drift in those tests was equivalent to
about 1 to 3 percent of the corresponding span concentration. Shutting the analyzers down over-
night produced no additional effect on zero or span drift. No interference was found from
elevated concentrations of S02, CO, C02, NH3, or hydrocarbons when each was present alone,
but a reduction of about 13 percent in response to 381 ppm NO was seen when S02 was also
present at about 450 ppm.
No significant effect of sample gas pressure on response to NO or N02 was found over the range
of+10 to -10 inches of water relative to the ambient atmosphere. Ambient temperature over the
range of 7.22° to 40.56°C (45° to 105°F) had a significant effect only on response to NO. The
effect was about a 5 percent increase in NO response at reduced temperature, and about a 6 per-
cent decrease in response to NO at elevated temperature, relative to response at room
temperature.
Accuracy of the Horiba PG-250 analyzers for NO ranged from less than 2 percent to about
8.5 percent relative to the reference method, in emission measurements on a range of sources.
However, accuracy for N02 from those same sources was relatively poor, ranging from about 35
to 50 percent. This result is attributed to the limited capacity of the N02 converters, as noted
above. The sources tested emitted predominantly NO, so the overall accuracy for NOx determi-
nation ranged from about 5 to 19 percent for the two PG-250 analyzers. Good accuracy for NOx
can only be expected, however, when the proportion of emitted NO is high relative to N02.
Comparison of selected results from the two PG-250 analyzers shows that they performed
essentially identically. The unit-to-unit agreement of the two PG-250 analyzers for NO and NOx in
source tests was usually better than that of the two reference analyzers.
52
-------
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).
53
-------
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 -
-------
ETV AMS Air Audit
Page 1
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
-------
ETV AMS Air Audit
Page 2
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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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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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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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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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.
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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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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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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
C02
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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