EPA-AA-TEB-83-2
Investigation of NOx Artifacts in Diesel Emission Tests
By
Edward Anthony Barth
January 1983
Test and Evaluation Branch
Emission Control Technology Division
Office of Mobile Sources
Environmental Protection Agency
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Investigation of NOx Artifacts in Diesel Emission Tests
INDEX
ABSTRACT Page 3
BACKGROUND Page 4
PROGRAM DESIGN Page 5
1. Methodology Page 5
2. Ames test Page 6
3. Artificial Combustion Air Page 6
4. Test Engine - Selection Criteria and Description Page 7
TEST PROCEDURES Page 8
1. Test System Page 8
2. Sample Size Page 11
3. Equipment Check Page 11
4. System Operating Checks and Adjustments Page 12
TEST RESULTS - AMES Mutagenicity Page 14
TEST RESULTS - GASEOUS AND PARTICULATE EMISSIONS Page 15
CONCLUSIONS Page 16
APPENDIXES
Appendix A Ames Bioassay Testing Page 18
Appendix B Physical Properties of the Combustion Gases Page 22
Appendix C Test Engine Description Page 23
Appendix D Artificial Air Analysis Page 24
Appendix E Fuel Analysis Page 24
Appendix F Operating Test Variables Page 25
Appendix G Test Filter Extraction Solubles Page 26
Appendix H ORD's Analysis of Ames Test Results
for the Artifact Samples Page 27
Appendix I Ames Test BioactLvity (linear regression model) Page 29
Appendix J Summary of Appendix I Page 30
Appendix K Ames Test Bioactivity (curve fitting model) Page 31
Appendix L Diesel Artifact Gaseous and Particulate Emissions Page 32
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ABSTRACT
It has been suggested by some researchers that there is a potential for
the diesel particulate sampling technique to alter the characteristics of
the samples. A test program was undertaken to investigate the effect of
diesel NOx emissions on diesel particulate samples collected in a manner
similar to standard EPA procedures. The specific purpose of the program
was to determine whether the NOx gases flowing across the particulates
trapped on the filtering media would alter the biological characteristics
of these samples. The test program was conducted from December 1978
through October 1979. Steady-state tests were run using a small,
single-cylinder diesel engine and the Ames bioassay technique was used on
the particulate samples to test for changes in biological activity.
The engine was tested using both No. 2 diesel fuel and a nitrogen-free
fuel (decane) using both air and a simulated nitrogen-free "air". These
tests provided an evaluation of the potential for diesel exhaust NOx
emissions to alter the characteristics of the particulate samples. The
Ames tests of these samples showed that the presence or absence of NOx
caused no significant difference in the bioassay activity of the
particulate samples.
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BACKGROUND
The Environmental Protection Agency has an ongoing program of studies to
investigate vehicle emissions and their related health effects. As part
of this effort, EPA's Emission Control Technology Division has for
several years been focusing a large effort on the detailed study of
diesel exhaust emissions.
The emissions of a diesel vehicle differ from the emissions of a gasoline
vehicle in several aspects. One of these is that there is a much greater
amount of carbonaceous particulate matter in the exhaust of a diesel
vehicle than in the exhaust of a gasoline fueled vehicle. Typically,
diesel vehicles emit 30 to 100 times more particulate per mile than a
catalyst-equipped gasoline vehicle. Since diesel vehicles are expected
to become an increasing percentage of the total vehicle population, the
contribution of the diesel emissions to the ambient total suspended
particulate (TSP) could be significant. Therefore, diesel particulate
levels are now regulated^.
Diesel particulate consists of both solid carbonaceous particulate matter
and organics bound to these solids. The study of the health effects of
these particulate-bound organics is the subject of considerable effort by
government, industry and educational institutions. A commonly used
method to investigate the biological activity, which may be health
related, of these organics is the Ames Test^.
Published work indicates that these particulate-bound organics may be
artificially modified by the sampling process due to the unusual
chemistry that can occur on the surface of the filter^. Because of the
•'•Standard for Emission of Particulate Regulations for Diesel Fueled
Light Duty Vehicles and Light Duty Trucks. 40 CRF Part 86 Published
March 5, 1980.
Test - bacteriological test, developed by Dr. Bruce Ames and
colleagues at the University of California at Berkley. The test is
used to evaluate the mutagenetic potential of compounds.
^Benzo[a] pyrene (BaP) is a known particulate-bound exhaust carcinogen
that is not directly active (mutagenic) in the Ames test. In order
for it to be an active mutagen in a body system, the Bap must be
activated by body enzymes. However, work by Dr. James N. Pitts of the
University of California at Riverside has shown "that when a filter
was preloaded with BaP and then a stream of 1 ppm N0£ (nitrogen
dioxide) and a carrier gas was drawn through it the BaP nitrosated to
nitrobenzo[a]pyrenes (the 1, 3 and 6 isomers). These nitrosated BaP
compounds are direct acting mutagens in the Ames test and as such do
not require metabolic activation." Reference: Memorandum dated
April 5, 1978 from Thomas M. Baines, EPA, to Charles L. Gray, EPA,
subject "Carcinogenesis, Dr. Bruce Ames, PNA's, and Characterization".
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potential impact of this effect on the accuracy of the test procedures
for unregulated emissions, the sampling methods needed to be further
studied. Therefore, EPA initiated a small in-house test program to
investigate whether NOx artificially influences the Ames test results.
The conclusions to be drawn from this EPA test effort are, necessarily,
of limited applicability to diesel vehicles. The Ames bacteria tester
strains used were those normally used in light-duty diesel vehicle
exhaust studies. The test engine was a small displacement, stationary,
diesel generator set and all testing was done at a constant speed and
load. Therefore, the conclusions of this EPA study can be considered to
be quantitatively valid only for the specific stationary diesel engine
tested and for only the specific Ames bacteria tester strains. However,
it is reasonable to suggest that similar trends may be observed in
vehicle testing for similar test conditions.
PROGRAM DESIGN
1. Methodology
During the engine combustion process, some of the nitrogen in the
combustion air is oxidized to nitrogen oxides (NOx). To determine if
NOx artifacts are introduced into the particulate samples gathered
for the Ames test, a diesel engine was tested both with and without
nitrogen in the fuel/"air" mixture. Diesel particulate samples were
obtained using both normal air and a nitrogen-free "air". The engine
was tested with both standard diesel fuel and a nitrogen-free fuel.
The nitrogen-free fuel, decane, was produced by reducing linear alpha
olefins. The fuels obtained by the process, (decane, duodecane, and
tetradecane) are nitrogen-free and readily separated. Since decane
is a light end component of diesel fuel, EPA anticipated no special
problems in starting or running the engine at the nominal test
temperature of 70°F.
To minimize the combustion air requirements, a small displacement
diesel engine was needed for the test program. To simplify the
application of the output shaft loads, a small-displacement diesel
generator set was selected.
Existing test procedures and equipment used to test diesel vehicles
were modified to permit their use in testing this single-cylinder
engine. A description of the procedures and equipment used is given
on page 8.
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2. Ames Test
The Ames test is a bacteriological technique which is used to
evaluate the mutagenic potential of compounds. For diesel
particulate emissions, test samples are gathered on a filter medium
and the soluble organic fraction (SOF) is later chemically separated
by Soxhlet extraction using either methyl or dimethyl chloride. The
initial extraction solvent is then removed and the SOF is then
dissolved in dimethyl sulfoxide (DMSO) for the bioassay tests. This
solvent-extract is placed in Petri dishes with various standardized
Salmonella Typhimurium bacteria tester strains to test the
mutagenicity of the chemical compound. A broader and more detailed
description of Ames bioassay testing and its applicability to diesels
is given in Appendix A. '
For Ames tests of vehicle exhaust emissions, the cooled (less than
125° F) diluted exhaust is passed through a large teflon-coated glass
fiber filter to trap the vehicle exhaust particulate. Typically, a
20x20 inch filter is installed in the diluted exhaust stream to trap
as much particulate matter as possible.
3. Artificial Combustion "Air"
Engines are designed to run on an air/fuel mixture which has very
specific properties. To determine the properties for the best
artificial "air" blend, researchers who were known to have had
experience with using various blends of artificial combustion "air"
were contacted to solicit their ideas as to the proper blend of gases
to be used when there is to be no nitrogen in the combustion "air".
These included individuals from the Air Force Propulsion Lab, Air
Force Environmental Activities Group, Amoco, Bureau of Mines, Cummins
Engine Company, GM Research*, GM Truck & Coach, Gulf Research*,
Essex*, University of California*, and the University of Michigan.
None of these individuals had done work under the particular test
conditions required in this project.
As a result of these discussions, a limited literature search, and
some preliminary calculations, criteria were developed for the blend
of gases used to replace nitrogen in the artificial "air":
a. The gases had to be chemically inert during the combustion
process.
b.' The gases should not aid or detract from the normal
combustion process.
c. The gases should be readily available.
Individuals from these organizations had actually conducted some
testing with artificial "air" blends.
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d. The blend of gases should have the same physical properties
as air in terms of density, molecular weight, specific heat
at constant pressure, specific heat at constant volume,
specific heat ratio, thermal capacity, and viscosity.
Based on the preceding considerations, a blend of 15% argon, 35%
carbon dioxide, 29% helium, and 21% oxygen was selected for the
nitrogen-free combustion "air". The physical properties of air and
this blend of gases are tabulated in Appendix B.
4. Test Engine - Selection Criteria and Description
The basic objective of this test program was to obtain particulate
samples for Ames analysis from a diesel engine operating on both
normal air and nitrogen-free "air". Since the testing would require
large amounts of this artificial combustion "air", the primary
criterion for selection of the engine was that it have a small
displacement. Similarity to passenger vehicle diesel combustion
chamber design, ease of testing, and availablility were secondary
requirements.
The engine selected was a small Onan diesel which is part of a
generator set model DJA. It is a 4 cycle, single-cylinder,
air-cooled 30 CID unit. A more detailed description is given in
Appendix C. ,
This engine had the following similarities to those used in a diesel
passenger vehicle:
a. compression ratio
b. displacement similar to that of individual cylinders on
raulticylinder passenger car diesel engine
c. 4 stroke cycle
d. indirect injection
e. precombustion chamber in head
f. governed rpm of 1800 which is reasonably representative of
that of an engine in a passenger vehicle that is cruising
at 50 mph.
This engine differed from those used in a passenger vehicle in that
it was air-cooled and restricted to steady-state operation.
Since such a small engine cannot be tested accurately on EPA's large
dynamometers, it was decided that it would be tested in its designed
application using resistive loads. This engine was tested at 65% of
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the maximum rated continuous load of the engine. This would provide
a sufficient amount of sample without requiring an excessive amount
of artificial "air". Since Ames samples are generally obtained
during a 50-55 mph cruise or the HFET and the principal difference in
using different driving cycles is the rate of particulate generation
(the amount of particulates generated per unit time usually increases
with engine load and the Ames response is not appreciably altered by
these load changes), these were not thought to be serious differences.
TEST PROCEDURES
The procedures and equipment used to gather Ames samples are a
modification of the procedures normally used to obtain particulate
samples of diesel vehicles using either the Federal Test Procedure (FTP)
or Highway Fuel Economy Test (HFET)^. The main difference is the
addition of a large filter to collect as large a sample of the
particulate as possible for the bioassay testing. The test procedures
and equipment used to obtain the diesel NOx artifact samples were
patterned on the test procedures used to obtain vehicle particulate
samples for Ames tests.
1. Test System
The particulate generation and collection system consisted of the
artificial "air" gas cylinders, the diesel generator set, a resistive
load bank, an 8-inch dilution tunnel, 47mm particulate sampling unit,
a bulk stream filter for the Ames sample, a positive displacement
pump (PDF) Constant Volume Sampler (CVS), auxiliary analyzers,
instrumentation, plumbing, and ductwork. A schematic of the test
set-up is given in Figure 1.
The particulate sampling system used an 8-inch dilution tunnel. The
exhaust gases and dilution air are mixed by the turbulent flow
created by the orifice plate in the tunnel. The exhaust enters the
tunnel at the plane of the orifice plate. The total particulate mass
was obtained by taking particulate samples on 47mm filters downstream
of the orfice plate. The filter probe had a knife edge and the flow
rate through the filter was adjusted to permit isokinetic sampling*.
The total particulate mass was then calculated by relating the flow
through the 47mm filter to the total flow through the tunnel. This
calculation is described in Reference 4. A drawing of the tunnel is
given in Figure 2.
^Environmental Protection Agency 40 CFR Part 86 Federal Register
Vol.45, No. 45, March 5, 1980 "Standard for Emission of
Particulate Regulation for Diesel-Fueled Light-Duty Vehicles and
Light-Duty Trucks".
*For isokinetic sampling, the velocity of the flow at the sample
probe is equal to the velocity of the free stream flow.
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HC, CO, C02, NOx
Analyzers
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Figure 1 Schematic of Test Set-Up
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to spectrophotometer
to HFID
to particulate
sample pump
47mm particulate
sample probe
dilute exhaust
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filter and CVS
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Figure 2. Schematic of Particulate Sample Dilution Tunnel
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Six A-size cylinders (200 cubic feet each) were manifolded together
to supply the artificial combustion "air". A pressure regulator
controlled the flow of this high pressure "air" to the flow control
orifice. Since the expansion through the orifice would cool the
"air" it was routed though 50 feet of copper tubing. This allowed
the "air" to warm to the ambient test temperature. The "air" then
passed into a large sealed bag that was attached to the air intake of
the engine. This system ensured that artificial "air" was at ambient
pressure, eliminated waste, permitted adjustment of the flow rate to
operating flow needs, allowed the engine to be readily switched
between air and artificial "air", and permitted the operator to
readily monitor and control the "air" flow.
2. Sample Size
For Ames bioassay testing, the particulate-extractable organics are
tested at several logarithmically spaced doses. Typically, a 2 mg/jil
solution of extractables in DMSO (2 milligrams of extractable organic
material per microliter of dimethylsulfoxide) is applied to the Ames
tester strain at six doses (SOOjil, SOOjil, lOOpl, 50jil, 30pl, and
lOpl) . Each dose is tested in triplicate, both with and without
metabolic activation for each of the five tester strains (See
Appendix A). The entire test is replicated. Thus, 600mg of organic
extractables are needed for a complete Ames test of a diesel
vehicle. With typical extraction efficiencies of 20%, a total of 3
to 5 grams of particulate must be collected on the filters used for
five tester strains.
Since the TSP generated by a diesel vehicle in any one FTP or HFET
provides insufficient sample for analysis, multiple HFET or 50-60 mph
steady-state tests on each of several filters are required to obtain
sufficient sample. Similarily, for these tests to investigate NOx
artifacts, the diesel generator set was operated at 65% load until
the filter was fully loaded with particulate matter. The limiting
factors were the reduction in flow and the tendency of the
particulates to flake off the filter as the particulates accumulate
on the filter. The 20x20 inch filters were able to be loaded with 1
to 3 grams of particulates.
3. Equipment Checkout
The test hardware for this testing was integrated into a system.
After the initial leak and functional checks of the total system, the
performance of the individual components of the system was verified.
The 47mm particulate sampling system (probe, filter, flowmeter, pump,
and plumbing) calibration was checked by using it concurrently with a
calibrated system installed in an 18-inch tunnel that was being used
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to test a vehicle. The artifact sampling system and the calibrated
vehicle system agreed to within better than 1/2% for each of the
three bags of the FTP test cycle.
The ability of the 8-inch tunnel to mix the exhaust and dilution air
was checked by traversing the tunnel at the gaseous and particulate
sampling plane. Good mixing was noted. There was less than five
percent variation across the tunnel.
Due to the potential effect that even a small amount of nitrogen
dioxide could have on the organic-bound particulates-^, it was
necessary to insure that the nitrogen-free "air" and the two fuels
did not contain trace amounts of nitrogen. The commercial methods
used to manufacture and fill the nitrogen-free "air" bottles could
allow trace amounts of nitrogen to exist as a contaminant—possibly
even as high as 1%. After combustion, some of this nitrogen would
be in the form of NO and N02, and therefore, negate the efforts of
this study. Since the bottles had been filled in batches, a sample
of each batch was analyzed for trace nitrogen by a commercial lab
using a gas chromatograph—mass spectrometer technique. The results
of this analysis, Appendix D, showed that there was no nitrogen
detected in the artificial "air" blend.
Similarily the two fuels were analyzed for trace nitrogen. Due to
the method used to manufacture the decane, it was unlikely to contain
a trace of nitrogen. However, diesel fuels may contain traces of
nitrogen compounds. Therefore, duplicate samples of the two fuels,
decane and diesel fuel No. 2, were analyzed for trace nitrogen. The
results of this analysis, Appendix E, showed that there was no
nitrogen detected in the fuels.
System Operating Checks and Adjustments
Because the test engine was new, it was necessary to break-in the
engine. During the 225 engine operating hours required for break-in,
the test setup and procedures were adjusted and modified to optimize
the sampling process. A list of the test conditions monitored and/or
controlled while operating the engine are given in Appendix F.
The engine was cyclically operated at 0,5,16, and 25 (the rated full
load) Amp loads for break-in. Emissions and fuel consumption were
monitored in order to determine when they had sufficiently stabilized
so that the test samples could be taken. The CVS flow rate was
adjusted to the minimum flowrate that would still maintain the
diluted exhaust temperature below 125°F. The particulate mass
flowrate (47mm filter) was then adjusted for isokinetic sampling at
the test load, 16 Amps, (65% of full load) and the minimum CVS flow
rate (100 CFM).
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Operating procedures were developed for the bulk stream filter used
to obtain the Ames samples. Due to the operating constraints of
dilute exhaust temperature, available CVS flow rates, bulk filter
size, and allowable pressure drop across the filter, it was necessary
to have a portion of the flow bypass the bulk filter. Also, due to
the reduction in flow across the filter as it loaded, it was
necessary to periodically readjust the bypass damper to maintain
adequate flow through the filter. Typically, at the test conditions,
the pressure drop across the filter was 5 inches water when new and
13 inches when fully loaded. Initially, an 8xlO-inch bulk stream
filter was used and the diluted exhaust was drawn through the filter
by a small pump. This filtered exhaust did not pass through the
CVS. After the 20X20-inch filter holder had been fabricated and
checked out, it was possible to pass most of the diluted exhaust
through the filter and the entire flow, both filtered and bypass,
passed through the CVS unit.
Engine operating performance was checked with artificial "air" and
with decane. Several artificial "air blends" with different C02
concentrations were tried. It was found that with the blend of 35%
C0£, 21% 02, 15% argon, and 29% helium, the engine operating
conditons were nearly the same as they were with air (see next
paragraph). With decane, a slight lowering of the exhaust gas
temperature (EGT) was noted.
Engine performance was characterized by gaseous emissions,
particulate emissions, fuel consumption, EGT, and generator amperage
and voltage. Except for the slight decrease in EGT noted when
operating with decane, engine operation (load and temperature) was
essentially unchanged for all test conditions.
The NOx in the normal engine exhaust consists principally of NO
(nitric oxide) and N02 (nitrogen dioxide) with most of it being
NO. Since the concentration of N02 was of specific interest,
additional techniques and equipment were employed to monitor N02.
Although most of the NOx in an exhaust sample is NO, the
concentration is not stable. The NO oxidizes to N02 until an
equilibrium condition is reached. The chemiluminescence analyzer
used for NOx analysis can be readily operated in a bypass mode to
detect only NO. During testing, some of the samples of the exhaust
were checked by this method and the NOx was found to be over 90% NO.
This implies that the N02 was less than 10% of the NOx for all
tests using air. A second derivative spectrophotometer, a Lear
Siegler SM400, was also used to check the nitrogen oxides. This
instrument is able to directly measure the dilute exhaust
concentrations in real time. This instrument showed the same
NO/N02 exhaust relation. A bag sample of the dilute exhaust was
also crosschecked with both instruments over a 50 minute period. As
expected, the concentration of NO continually decreased. Both
instruments tracked this change and were in good agreement throughout
this check.
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TEST RESULTS-AMES MUTAGENICITY
Due to scheduling priorities, the Ames analyses of the test samples was
to be done a considerable time after the samples were generated.
Therefore, as an initial screening control, the particulate SOF was
tested for 3aP* by HPLC ** to insure meaningful samples were being
generated. The results of this extraction and screening are given in
Appendix G^.
The particulate samples for the Ames analysis were all taken at 65% load
and 1800 rpm. The Ames results are given in Appendixes I, J, and K and
are more fully discussed by our Characterization and Technology
Assessment Branch in the analysis given in Appendix H. The results of
the diesel artifact testing are expressed by both the linear regression
(Appendix I) and curve fitting (Appendix K) models. The results of the
individual tests are also summarized as an average dose/response
relationship (Appendix J) for the linear regression model.
Overall, for the four test fuel/"air" combinations, there were no
significant differences in Ames activity when comparing like samples,
i.e. samples with (metabolic) activation to samples with activation and
samples without activation to samples without activation for the five
Ames tester strains used.
There were differences in Ames activity between samples with activation
and without activation for the decane and artificial air tests.
Differences were also observed to a lesser degree in the diesel fuel and
artificial air experiments. These results indicate that it is possible
that the lack of nitrogen may have caused a decrease in direct acting
mutagens. However, as noted in Appendix H, these observed differences
are within the acceptable limits for Ames test variability for the test
configuration.
*BaP - Benzo[a]pyrene - is a known carcinogen, gives a positive Ames
response, and is a normal component of diesel exhaust.
**HPLC-High Performance Liquid Chromatography - a fractionation
technique used to separate the compounds in the sample. The amount
of BaP was then determined by using UV with flourescence detection at
specific wave lengths.
-"Fuel and lubricants are inactive in the Ames test. Most of the
organic extract is inactive fuel and lubricant derived material
which serves only to dilute the sample and obscure the analysis.
Reference: Pre-test discussions with EPA researchers who were
conducting Ames tests on diesel particulates.
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15
Therefore, the overall conclusion is that, for these test conditions, the
Ames tests showed that the presence or absence of NOx caused no
significant difference in the bioassay activity of the particulate
samples. That is, there were no NOx artifacts observed in the Ames tests.
TEST RESULTS-GASEOUS AND PARTICULATE EMISSIONS
The gaseous and particulate emission results are given in Appendix L.
The emission levels are given in grams per kilowatt hour and the fuel
consumption is in kilowatt hours per gallon. These values are expressed
for the generator output rather than the engine output since the actual
efficiency* of the generator was unknown. These data were all taken at
65% load and 1800 rpm.
Although it appears there are significant differences in gaseous and
particulate emissions for the four test conditions, some of these
differences are not as significant as they might otherwise appear due to
changes in engine emission characteristics that were observed throughout
the test program. The following factors affecting these results were
noted:
1. There were long term trends of continually lower gaseous and
particulate emission levels. This new engine was operated for
over 225 hours before official testing began. Emissions were
periodically checked throughout this break-in period and at 225
hours these downward trends, although not stopped, were judged
to have sufficiently stabilized for the purposes of this test
program. Post test checks confirmed that these downward trends
had continued and that the changes were still acceptable.
2. The testing occurred sequentially in the order given in Appendix
L. Since it took several hours at each test condition to obtain
a sufficient particulate sample for Ames analysis, over 50 hours
elapsed between the start and end of testing.
3. The engine periodically exhibited changes in one or more
pollutants that would last throughout the sample period, i.e.,
for decane-normal air testing the hydrocarbon levels changed.
However the differences of the following items in Appendix L are probably
significant:
1. With normal air, the NOx emissions are lower with decane than
with No. 2 diesel fuel. This may be due to lower peak
combustion temperatures and/or reduction of the NOx that is
formed.
*At the test conditions of 60% load at 1800 rpm, the generator
efficiency was probably about 90%.
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2. The very low levels of NOx with artificial "air" are due
principally to the minimal amount of nitrogen in the combustion
oxidizer.
3. The levels of NOx with decane and artificial "air" are extremely
low, even lower than the No. 2 diesel fuel and artificial "air"
tests. The NOx gaseous samples were considerably less than 1
ppm and close to the background NOx levels. This could be
expected based on items 1 and 2. However the difference in NOx
levels for the two artificial "air" tests could also occur if
the artificial "air" blend used for the No. 2 diesel fuel tests
possibly had a higher level of nitrogen as an unmeasured
contaminant gas than the blend used for the decane tests.*
Another source of differences in these NOx levels could occur if
the No. 2 diesel fuel had a small amount of nitrogen as an
unmeasured contaminant (below the detection limit). No. 2
diesel fuel usually contains some nitrogen but the decane,
because of the manner in which it was manufactured, is nitrogen
free. However, since the minimum detectable level for the
nitrogen in the fuel was one-third of that for the nitrogen-free
"air" and the ratio of air to fuel is about 20 to 1, the fuel is
a less likely source of nitrogen for these low levels of NOx
than the combustion air.
4. The high levels of CO for the decane-artificial "air" tests is
probably real.
CONCLUSIONS
A 30 cubic inch, single-cylinder diesel engine was successfully operated
using two fuels and two combustion gases. The fuel and combustion air
combinations tested were:
1. No. 2 diesel fuel and standard air
2. decane fuel and standard air
*The absolute level of nitrogen in the artificial "air" was not
determined. In all cases it was not detectable. That is, the nitrogen
content was below the minimal detectable level of 100 ppm nitrogen.
**Similarly the absolute level of nitrogen in the fuels was not
determined. For both fuels it was not dectable. That is, the nitrogen
content was below the minimal detectable level of 30 ppm nitrogen.
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3. No. 2 diesel fuel and an artificial, nitrogen-free, "air" (21%
oxygen, 35% carbon dioxide, 15% argon, and 29% helium)
4. decane fuel and artificial "air" (same blend).
Gaseous emission and particulate samples were obtained at 60% load for
the preceding fuel/"air" combinations. The same test equipment and
procedures that are used to test diesel vehicles were used to the maximum
extent possible. High volume particulate samples were collected using
either 8x10 inch or 20x20 inch filters for extraction and subsequent
bioassay analysis by the Ames Test. There were no difficulties
encountered when operating the engine on decane or artificial "air".
Except for NOx, the gaseous and particulate emission data were similar
for all test conditions. As expected, the NOx values were very low for
the tests using nitrogen-free "air".
Overall, for the four test fuel/"air" combinations, there were no
significant differences in Ames activity when comparing like samples,
i.e. , samples with (metabolic) activation to samples with activation and
samples without activation to samples without activation for the five
Ames tester strains used.
There were differences in Ames activity between samples with activation
and without activation for the decane and artificial air tests.
Differences were also observed to a lesser degree in the diesel fuel and
artificial air experiments. These results indicate that it is possible
that the lack of nitrogen may have caused a decrease in direct acting
mutagens. However, these observed differences are within the acceptable
limits for Ames test variability for the test configuration.
Therefore, the overall conclusion is that, for these test conditions,
there were no NOx artifacts observed in the Ames tests.
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APPENDIX A
Ames Bioassay Testing
1. Purpose of the Ames Test
The Ames bioassay was developed by Dr. Bruce Ames of University of
California as a screening test for potential carcinogens. The
advantage of this test is that it can be conducted at a small
fraction of the cost and time required for whole animal tests.
According to Dr. Ames, when known carcinogens have been tested with
the Ames bioassay, up to 80-90% of them have yielded positive
mutagenic responses. On substances that have been shown not to be
carcinogenic in whole animal tests, only about 10% yield positive
mutagenic responses on the Ames test". Therefore, Dr. Ames feels
that mutagenicity, as determined by the Ames bioassay, correlates
reasonably well with carcinogenicity and can be used as an indicator
of potential carcinogenicity. Other researchers feel that the
positives are not as high a percentage.
2. Description of the Ames Test
The Ames test is a bioassay utilizing various strains of a certain
bacteria, Salmonella Typhimurium, to test for the mutagenicity of
chemical compounds. In the testing of diesel exhaust particulate,
the organic bound fraction of the particulates collected on the glass
fiber filter are extracted with methylene chloride. The methylene
chloride is then evaporated and the residue is compared to the
original filter particulate loading to determine the "percent
extractable". An organic solvent, such as dimethysulfoxide (DMSO) is
used to dissolve this fraction of the particulate for subsequent
bioassay tests. A measured quantity of this diluted extract is then
placed in a Petri dish with a strain of the Salmonella bacteria.
Tests are conducted with various tester strains because different
types of mutagens are detected by different strains of the bacteria.
The strains of Salmonella used in the test are histidine-requiring
strains, but they are mutant strains which are unable to produce
their own histidine. Therefore, unless histidine is supplied to them
or something causes them to revert to their original,
histidine-producing form, they will die. For the Ames test itself,
the mutant strain is placed in a Petri dish with the chemical being
tested and with a minimal amount of histidine (enough for a few cell
divisions). If the chemical mutates the bacteria (thus correcting
the genetic defect), the Salmonella returns to normal, produces
histidine, and is able to survive. Those that do not revert, die
upon using up the small amount of histidine available. By counting
the number of colonies of surviving bacteria that have thus
"reverted", an indication of the mutagenic potential of the chemical
can be obtained.
^Memorandum dated April 5, 1978 from Thomas M. Baines, EPA, to
Charles L. Gray, EPA, subject "Carcinogenesis, Dr. Bruce Ames,
PNA's, and Characterization."
-------
19
A chemical that causes a statistically significant increase in the
number of revertants is said to have given a positive Ames response.
Conversely, a chemical that does not cause a statistically
significant increase in the number of revertents is said to have
given a negative Ames response.
Dr. Ames and his colleagues have developed several tester strains of
Salmonella that are able to differentiate between various types of
mutation. For example, one mutation type would be a point mutation
where a specific sector of the DNA molecule would be disrupted, thus
yielding a mutation. Another type of mutation would be the frame
shift mutation which occurs in the repetitive sequence areas of the
DNA. This slippage occurs only in these repetitive sequence areas
and involves a much larger portion of the DNA.
In order to make the tests more valid, Dr. Ames eliminated the DNA
repair enzyme from the tester strains. Therefore, in the event that
a mutagenic compound affects the DNA, the DNA repair mechanism of the
cell will not be activated, thus repairing the damage done by the
chemical and thereby masking the mutagenicity of the chemical.
They have also developed a process by which they strip the
lipopolysacchride sheath from the exterior of the bacterial membrane
wall. This lipopolysacchride membrane serves to resist the entrance
of certain chemical species. With this barrier stripped off the
cells, they will take up a wider variety of chemicals.
3. Metabolic Activation of the Ames Samples
Many chemicals cause cancer by mutating. Certain polynuclear
aromatics (PNA) such as BaP (a diesel exhaust component) have been
proven to be carcinogenic but they are not by themselves mutagens.
However, BaP is one of a group of chemicals that are transformed in
the body to a form that can be carcinogenic. For example, liver
contains enzymes that are very effective at transforming these
compounds into mutagenic/carcinogenic compounds. In order for the
Ames test to make a truly effective analysis of this class of
compounds, the compounds must be converted into the chemically active
form. This is done by metabolically "activating" them with compounds
such as a liver microsomal extract obtained from ground up rat
liver. The samples are therefore tested for Ames response:
a. without metabolic activation - i.e., directly
b. with metabolic activation
-------
20
4. Application of the Ames Test to Diesel Vehicles
Most of the organic diesel exhaust products that are Ames reactive
condense on the exhaust solid particulates. The diluted cooled
exhaust is filtered to trap these particulates and then the organic
fraction is chemically extracted. This extract is then tested for
Ames response, both with and without activation. The following
Salmonella tester strains have proven useful for diesel studies.
a. TA 98 is a frame shift detection strain; the particulate extract
from diesel vehicles usually gives a positive response to this
tester strain.
b. TA 100 is a point mutation detection strain; the particulate
extract from diesel vehicles usually gives a strong positive
response to this strain.
c. TA 1535 is a point mutation detection strain; the particulate
extract from diesel vehicles usually gives a negative response
to this tester strain. It therefore serves as both a control
and detector of unusual activity.
d. TA 1537 is a frame shift detection strain; the particulate
extract from diesel vehicles usually gives a positive response
to this tester strain.
e. TA 1538 is a frame shift detection strain; the particulate
extract from diesel vehicles usually gives a positive response
to this tester strain.
5. Ames Results - presentation of data
The Ames test result is a dose/response result. Each tester strain
is tested at several logarithmically spaced dose levels. The
response (number of revertants), is a measure of the mutagenic
potential of the compound. The results are corrected for spontaneous
revertants and then expressed by a dose/response relationship as the
slope of the curve.
A major problem with the Ames test is toxicity. As the dose is
increased, the potential of the bioassay systems to produce
revertants is hampered by a concurrent increase in toxicity.
Therefore, there is typically a dose level at which the results are
not meaningful. To account for these difficulties, various
techniques are used to screen the data and to present the results.
Two methods of data presentation were employed here since the
modeling/methods of presentation are still being developed.
-------
21
The linear regression model expresses the results as a slope —
revertants per microgram of diluted extract. The other model, the
curve fitting model, corrects the results for the rate at which the
Ames assay becomes toxic. The results are again expressed as a slope
— revertants per microgram of diluted extract. Therefore, because
of this correction factor, the mutagenic rate predicted by the curve
fitting model is higher than that for the linear regression model.
Since the methods of presentation of data were still being developed,
the results of the diesel artifact testing are expressed by both
methods. The results of the individual tests are also summarized as
an average dose response relationship.
6. Handling and storage of particulate filters.
In the absence of completed studies on the handling, storage, and
shipping of diesel particulate samples for chemical and biological
analysis, the following procedures were developed with the help of
ORD to preserve the sample integrity;
a. Polyethylene disposable gloves were worn by the technicians
handling the filters. This protected the technician from
contact with the filter particulates. The gloves also protected
the clean and particulate laden filters from biological
contamination by the technicians.
b. The loaded filters were handled in the dark or under yellow
light (Eastman Kodak Kodachrome Yellow II filter) to minimize
the possibility of ultraviolet (UV) light altering this
biological sample. BaP, a typical particulate bound component
of diesel exhaust, is altered by UV light.
c. The loaded filters were double folded to prevent sample loss in
handling.
d. The folded, loaded filters were placed in a glassine envelope
and then in a manila envelope. The manila envelope was placed
in a Ziplock plastic bag which was sealed inside a polyethylene
plastic bag.
e. The sealed, loaded filters were stored in the dark at -30° C
(-22°F) to preserve the biological sample.
f. For shipment the samples were packed with dry ice in an
insulated shipping container. The samples were sent to EPA at
Research Triangle Park (RTF) for chemical extraction and Ames
testing.
-------
22
Gas
Argon
Carbon Dioxide
Helium
Nitrogen
Oxygen
Air
Nitrogen-free
"air"
APPENDIX B
Physical Properties of the Combustion Gases*
Density Molecular Specific Specific Thermal Viscosity
gm/1 Weight heat ** heat ratio Capacity Poises x
Cp Cp/Cv ***
1.78
1.98
.18
1.25
1.43
1.29
1.31
39.94
44.00
4.00
28.01
32.00
28.95
29.27
.12
.20
..25
.24
.22
.24
.49
.67
.30
.66
.40
.40
.40
1.48
.22
.39
.22
.30
.31
.31
.30
224
146
197
171
196
181
183
* Properties of the nitrogen-free artificial "air" were calculated by
ssuming that they are the percentage weighted sums of the properties
of the individual gases. These are based on a blend of 15% argon, 35%
carbon dioxide, 29% helium, and 21% oxygen by volume.
** Cp is gram-cal per gram (Btu per pound) at constant pressure.
***Thermal capacity is the density x Cp.
-------
23
APPENDIX C
Test Engine Description
3000 Watt Onan Diesel Generator Series DJA
Engine
mfg Onan
model DJA
type 4 cycle diesel, single cylinder over-
head valve
bore and stroke 3.25 x 3.625 in/82.6 x 92.0 mm
displacement 30 CID/491.6 cc
compression ratio 19 : 1
maximum continuous power @rpm 5.7 horsepower/4.25 kW @1800 rpm
combustion chamber precombustion chamber in head
governor gear driven, mechanical flyball
governed speed 1800 rpm, stable within +. 3%
cooling aircooled by centrifugal flywheel
blower
fuel system American Bosch injection pump with
pintle injection nozzle
fuel Diesel no. 2, tested with Diesel no.
2 and decane
starting aids intake air preheater, glow plug, and
a decompression solenoid
Generator
mf g Onan
type revolving armature, 4 pole, self
excited, mounted to engine shaft
volts/amps 120/240 volts 25/12.5 amps
pha se 1
power 3000 Watts
frequency 60 Hertz
frequency regulation 3 Hertz no load to full load
cooling direct drive, centrifugal blower
-------
24
APPENDIX D
Artificial Air Analysis by Gas Chromatography
Mass Spectrometer
Bottle Nominal BlendC1) Analysis
No. gas percentages Nitrogen Carbon Dioxide Oxygen Argon Helium (>JJ
1 0, 35, 21, 15, 29 ND(2) 35.4% 16.9% 14.6% NA
2 0, 35, 21, 15, 29 ND 32.9% 21% 12.6% NA
3 0, 35, 21, 15, 29 ND 34.8% 23.3% 13.5% NA
4 0, 35, 21, 15, 29 ND 38.8% 16.5% 13.5% NA
5 0, 30, 21, 20, 29 ND 28.4% 19.3% 17.6% NA
(1) Percentages of nitrogen, carbon dioxide, oxygen, argon, and helium
respectively.
(2) ND - not detectable, below minimal detectable level of 100 ppm
nitrogen.
(3) Helium content was not measured as this gas is used as the carrier gas
in the analysis.
APPENDIX E
Fuel Analysis for Trace Nitrogen
by Gas Chromatography with Thermal Conductivity
No. 2 diesel Fuel ND (duplicate analysis)
Decane ND (duplicate analysis)
ND - Not detectable below minimal detectable level of 30 ppm nitrogen.
Blank samples also had no nitrogen response.
Note: Analysis by gas chromatograph analysis with thermal conductivity.
Procedure used combustion with a hot catalyst to eliminate oxygen present
and break up NOx.
-------
25
APPENDIX F
Operating Test Conditions Measured and Controlled
CVS
Emissions
Generator
Filter weights
47mm particulate
sampling unit
Pressures
Temperatures
Time
dilute exhaust volume, time
HC, CO, C02> and NOx with standard gas
analysis system
HC by HFID (Heated Flame lonization Detector) for
total hydrocarbons
NO with standard gas analysis system in bypass
mode
NO directly with second derrivative
spectrophotometer
amperage, frequency, voltage
bulk stream filter before and after test
47mm filter before and after test
volume through 47mm filter
barometric, pressure drop across bulk stream
filter
ambient dry bulb
ambient wet bulb
artificial air at engine inlet
dilute exhaust temperature
exhaust gas temperature (EGT)
47mm sampling system at filter probe and gas flow
meter
HFID at sample probe, inline filter, sample line,
and oven
sample time, total engine operating time
-------
26
Ame s ' '
Sample No.
TAEB-79-
Diesel Fuel No.
0001 !
0002
0003
0004
0005
Decane - Normal
0012
0013
0014
0015
0016
Diesel Fuel No.
0047
0048
0049
0050
Solubles^2)
Extracted
2 - Normal Air
.458 gm
.275 gm
.544 gm
.476 gm
.336 gm
Air
.972 gm
.481 gm
.682 gm
.800 gm
.375 gm
2 - Artificial Air
.507 gm
.405 gm
.770 gm
.208 gm
Decane - Artificial Air
0059
0060
0061
0062
0063
0064
0065
0066
0067
.139 gm
.221 gm
.221 gm
.157 gm
.227 gm
.275 gm
.250 gm
.244 gm
.256 gm
APPENDIX G
Test Filter Extraction Solubles
Extraction^)
Efficiency
30%
22%
39%
36%
44%(5)
53%(5)
59%(5)
28%
29%
30%
31%
30%
32%
30%
29%
29%
Extracted
2.35 jigm
2.03 jigm
1.52 pgm
1.31 jigm
4.71 jigm
1.31 jigm
.92 togm
1.39 jigm
.53 jigm
12.66 jigm
22.06 jigm
13.76 pgm
11.03 jigm
11.00 jigm
22.96 jigm
18.43 jigm
16.58 ugm
12.16 ;igm
(1) All four digit numbers in first column have the prefix TAEB-79-.
(2) Methylene chloride soluble organics extracted from large particulate
filter (8X10 inch or 20X20 inch).
(3) Soluble organics extracted as a percentage of the total particulate
loading.
(4) Amount of Bap contained Ln soluble organics.
(5) Relatively high extraction efficiency due to oil residue in the
sample.
-------
APPENDIX H
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
PATE-.
SUBJECT:
FROM:
September 12, 1980
ORD's Analysis of Ames Test Results for the Artifact Samples
Karl H. Hellman, Chief, CTAB
TO:
Ralph Stahman, Chief, TEB
In my memo of 6 June 1980 entitled "Preliminary Ames Test Results for
TAEB Artifact Samples", I explained the situation with ORD concerning
the analysis of Ames test data. At that time, ORD had not fully developed
their computer programs for analyzing Ames data, so we analyzed the data
ourselves. Since my memo, ORD has completed its development of the data
analysis program for the Ames test and has reduced the data from the
artifact experiments. These data are presented in this memo.
The analyzed artifact data represents two types of reduction methodologies.
One method is based on a linear regression model. This is the basic
method we used in our analysis of the artifact data (our memo is attached).
However, the ORD method for linear regression analysis is different in
at least one way; that they used the net number of revertants (number of
revertants at a given dose minus the spontaneous revertants) while we
used the total number of revertants (number of revertants at a given
dose). There may well be other differences between our method of analysis
and ORD's of which we are currently unaware. When we receive a written
copy of ORD's present linear regression method (which is currently being
written) a more complete list of differences will be presented to you.
The data presented in Table 1 has been analyzed by ORD's linear regression
method. The data from Table 1 is summarized in Table 2.
After analyzing the data in Table 1, Larry Claxton concludes that
within the four major divisions of this experiment, (Diesel Fuel (DF)
2 - Normal Air, Decane - Normal Air, DF2- Artificial Air, and Decane -
Artificial Air), there are no significant differences when comparing
like samples, i.e. samples with activation to samples with activation,
samples without activation to samples without activation. The only
exception is sample TAEB-79-0012. Larry contends that the results for
samples TAEB-79-0013 through 0016 are in good agreement with one another
and that the results for 0012 is an anomaly. Because of this observation,
I did not include TAEB-79-0012 in the average of the Decane-Normal Air
experiment.
Another observation which Larry notes is the difference between samples
with activation and without activation in the Decane-Artificial Air
experiment. In. this experiment, the samples with activation gave con-
EPA Form 1320-6 (Rev. 3-76)
-------
28
sistently higher revertants per plate per ug extract values than those
without activation in all the strains which gave positive results. This
trend can also be seen in the DF2-Artificial Air experiment, but to a
lesser degree. Since the results from samples tested without activation
are indicative of the presence or absence of direct acting mutagens, and
since the trend of higher values for samples with activation versus
without is seen only in Artificial Air experiments and not Normal Air
experiments, one might assume a decrease in direct acting mutagens due
to the lack of nitrogen in the Artificial Air. The decrease in direct
acting mutagens can be seen if one uses Table 2 to compare the results
of strain TA100 for all four experiments, and strain TA98 for the
Decane-Artificial Air versus the Decane-Normal Air experiment. In each
case, the samples produced with Artifical Air and tested without activation
are less than those samples produced with Normal Air and tested without
activation. With the Ames test there are large variations in results
and these differences may fall within acceptable limits of variation,
but there is a consistent trend of lower values for samples produced
with Artificial Air and tested without activation.
The results shown in Table 3 are the data analyzed by Larry Claxton's
and ORD's model based on curve fitting rather than linear regression.
Attached is a draft report entitled "Modelling the Ames Test" which
explains the basis for the curve fitting mode. This draft is being
revised and we will pass on a copy of the revised draft as soon as we
receive one.
The curve fitting data from Table 3 show the same general trend which is
mentioned above for the linear regression mode. Table 3 does not contain
any averaged values since numerous samples were considered statistically
unacceptable for within-experiment comparison by Larry Claxton. The
reasons for the unacceptable sample data are listed at the bottom of
Table 3. I have also included Larry Claxton's summary sheets as an
attachment.
Attachments
NOTE TABLE 1 is APPENDIX I, Page 28
TABLE 2 is APPENDIX J, Page 29
Table 3 is APPENDIX K, Page 30
-------
29
APPENDIX I
Ames Test Bioactivity (linear regression model)
Slopes (revertants per plate/ug extract)
with activation/without activation
Sample No.
TAB B-79-
TA100
TA1535
TA1537
TA1538
TA98
DF2-Normal Air
0001
0002
0003
0004
Avg.
.51/.82
.447.59
.467.56
7.71
.477.67
0
-/-
.167.09
.39/.22
.29/.17
.3S/.22
.35/.20
.34/.20
.61/.42
Decane-Normal Air
0012
0013
0014
0015
0016
Avg.
DF2-Artificial
0047
0048
0049
0050
Avg.
-/-
.327.42
.45/1.14
.59/1.29
.627.81
.507.92
Air
.707.61
.437.22
.307.18
.167.14
.407.29
-7-
-7-
-7-
— /—
-/-
-/-.
.03(?)/.03('O
-/-
-/-
-7-
— /—
-/-
.077.04
.097.07
.117.11
.177.14
.117.09
.267.13
.107.03
.097.01
.047.01
.12/.04
.12/.06
.21/.15
.30/.16
.447.22
.547.31
.37/.21
.S4/.54
.30/.15
.13/.12
.20/.07
.37/.22
.14/.05
.26/.18
.32/.22
.50/.48
.67/.46
.44/.34
1.69/.70
.45/.12
.26/.06
.19/.07
.6S/.24
Decane-Artif ical Air
0591
0601
0621
Avg.
*
All 4 digit
o
1.06/.16
.61/.20
.27/.07
.65/.14
numbers in
-/-
-/-
—7-
-7-
first column have
.64/.03
.20/.03
.13/.09
.32/.05
the prefix
.20/.05
.27/.08
.18/.05
.22/.06
TAEB-79-
.24/.07
.30/.09
.25/.08
.26/.08
-Indicates a negative result
-------
30
APPENDIX J
Summary of Table 1
Averaged Slopes (revertants per plate/ug extract),
with activation/without activation
DF2-Normal Air
Decane-Normal Air
DF2-Artificial Air
Decane-Artificial Air .65/.14
TA100
.A7/.67
.50/. 92
.40/.29
.65/.14
TA1535
-7-
-/-
-7-
TA1537
.11/.09
.12/.04
.32/.05
TA1538
.34/.20
.377.21
.377.22
.22/.06
TA98
. '
.447.34
.657.24
.267.08
-------
APPENDIX K
Ames Test Bioactivity (Curve fitting model)
Slope (revertants per plate/ug extract)
with activation/without activation
1.20/2.58
.85a/2.78a
1.32a/1.40a
1.27a/1.63a
TAEB-79-
DF2-Normal Air TA100
0001
0002
0003
0004
Decane-Normal Air
0012
0013
0014
0015
0016
DF2-Artificial Air
0047
0048
0049
0050 .40u/.35
TA1535
+d/+d
0.4/.08
—/—
.17s/-
Decane-Artificial Air
0591
0601
0621
2.25h/.16b
1.717. 43
+d/.08g
-7
—f
TA1537
TA1538
TA98
0.27/0.26 1.21/0.56 1.02b/1.09b
3.19a/0.29a
1.85a/1.27a
1.30a/0.43a
0.3#V-
1.07/1.30
1.49/2.64
1.49/3.38
2.25/2.94°
-/-
-/-
-/-
-/-
-7-
ie/-
0.16/0.22
0.26/0.38
0.19/0.13
0.42/0.23
0.12/0.06
0.41/0.46
0.90/0.49
1.33/0.51
1.30/0.71
0.29/0.27
0.26/0.47
0.67/0.56
0.89/107°
1.40/1.41
.66/.14 2.06/1.18 +d/+d
.21/.06 .70/.26 1.20/.24
.207.02 .45/.15 .577.12
.048/.02S .04/.078 .19/.07
1.47/.03g 1.28/0.118 1-28/°'22S
1.54/.038 1.408/0.08hl.41/0.27s
.967.51 0.50/0.06g 1.88/0.22
a - only 4 dose levels and the degrees for freedom for the adequacy test is zero
b - low p valve for adequacy of fit, results not comparable to 'other samples
c - data does not fit model adequately
d - samples are positive, slope unattainable for statistical reasons
e - questionable positive
f - chi-square of Pousson low, result not comparable to other samples
g - low response when confidence limits considered
h - low p valve for mode.
-------
32
APPENDIX L
Diesel Artifact Gaseous and Particulate Emissions at 60% Load
Ames
Sample No.^
TAEB-79- Test No.
Emissions gms/kW-hr
HFID CO C02 NOx
Particu- Particulate Fuel
NOx lates(2) filter consumption
ppm gms/kw-hr efficiency kW-hr/gal(3)
Diesel Fuel No. 2 - Normal Air
0001
0002
0003
0004
0005
79-6855
"
79-6856
"
79-6857
'*
M
79-6858
"
11
79-6859
it
"
Decane-Norraal Air
0012
0013
0014
0015
0016
79-6493
••
"
79-7457
* *
79-7465
"
79-7458
**
79-7464
••
.65
.50
.52
.65
.64
.60
.33
.56
.44
.51
.63
.46
.45
.47
.46
(5)
1.25
1.44
2.05
-
-
-
-
-
-
.65
.71
3
3
3
3
3
3
2
2
2
2
2
2
2
2
2
3
3
4
3
3
3
3
3
2
3
2
.19
.27
.33
.27
.47
.09
.23
.45
.41
.18
.39
.36
.48
.30
.21
.24
.98
.14
.63
.52
.08
.33
.17
.75
.27
.67
1508
1499
1552
1631
1617
1562
1589
1493
1484
1337
1367
1374
1356
1443
1425
1313
1356
1428
1314
1360
1315
1399
1290
1357
1308
1212
10.94
10.67
11.11
13.48
12.24
11.63
12.39
12.37
12.66
11.84
12.67
12.40
11.85
12.44
12.59
7.89
8.29
8.96
7.99
8.23
7.91
8.27
8.02
8.51
7.98
7.45
66
64
67
68
62
59
71
71
73
67
72
70
69
73
74
46
49
52
47
49
45
48
50
54
50
47
.4 14.1
.2
• 1 "™
.9 28.3
.6
.1
.9 8.3
.6
.4
.7 7.9
• J "~
.1
.7 12.1
.1
.0
.7 3.3
.0
.9
.8 3.3
.1
.9 2.1
.0
.9 1.8
.7
.9 2.2
.4
99%
—
—
93%
-
—
97%
—
—
91%
-
-
91%
-
-
97%
—
—
94%
-
91%
-
91%
-
95%
-
6
6
6
6
6
6
6
6
6
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
8
.7
.8
.5
.2
.3
.5
.4
.8
.8
.6
.4
.4
.5
.0
.1
.7
.5
.1
.7
.4
.7
.2
.8
.5
.7
.4
-------
33
Ames
Sample No. 'I' Emissions gms/kW-hr
TAEB-79- Test No. HFID CO C02 NOx
Diesel Fuel No. -2 Artifical "Air" (5)
0047
0048
0049&
0050
79-9399
.67 3.29 (6)
.06 3.29 (6)
.06 3.20 (6)
Decane - Artificial "Air" (4)
0059
thru
0067
.21
.19
.20
79-7757 1.71 19.57 (6) .07
79-9401 - 19.56 (6) .05
NOx
ppm
1.1
1.0
1.1
.4
.3
Particu- Particulate Fuel
lates(2) filter consumption
gms/kw-hr efficiency kW-hr/gal(3'
1.4
82%
2.8
(6)
(6)
(6)
(6)
(6)
(1) All four digit numbers in first column have the prefix TAEB-79-.
Ames samples were taken using either an 8X10 inch filter or 20X20
inch filter.
(2) Particulate emission rate and efficiency were obtained using a 47mm
filter. These filter samples were taken at the same time as the
gaseous samples. However only one particulate sample was obtained
for each group since the time required to obtain a sufficient loading
on the 47mm filter was considerably longer than the time required to
obtain a gaseous sample.
(3) Fuel consumption was calculated by the carbon balance technique.
Fuel consumption of decane is expressed as the equivalent quanity of
diesel fuel No. 2.
(4) Nine 8 X 10 inch filters were used in sequence for each Ames sample.
Gaseous samples were obtained before and after the Ames samples.
(5) One 20 X 20 inch filter was taken for the Ames sample. Gaseous
samples were obtained before and after the Ames sample.
(6) Carbon Dioxide and fuel economy were not calculated for the
artificial ,"air" sample since the artificial "air" contained
approximately 35% C02 and, therefore, the dilute exhaust C02
levels were outside the range of the highest instrument calibrations
normally used. Also the exact C02 concentration of each bottle of
the blended "air" was unknown. Thus, fuel consumption could not be
calculated by the carbon balance technique.
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