EPA-AA-SDSB-82-08
Technical Report
Interim Report for
EPA/EMA Cooperative Test Program
By
Alex Azary
March 1982
NOTICE
Technical Reports do not necessarily represent final EPA
decisions or positions. They are intended to present
technical analysis of issues using data which are currently
available. The purpose in the release of such reports is to
facilitate the exchange of technical information and to
inform the public of technical developments which may form
the basis for a final EPA decision, position or regulatory
action.
Standards Development and Support Branch
Emission Control Technology Division
Office of Mobile Source Air Pollution Control
Office of Air, Noise and Radiation
U. S. Environmental Protection Agency
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Table of Contents
Section Page
I. Introduction 1
II. Inter-Lab Variability 1
III. Intra-Lab Variability 2
IV. Summary 2
References 3
Tables 4
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I. Introduction
The Engine Manufacturers Association/Environmental Protection
Agency (EMA/EPA) cooperative test program was initiated in May
1981 to analyze lab-to-lab variability in particulate emission
measurements and to assess whether or not the large amount of
transient emissions data generated at the Southwest Research Ins-
titute (SwRI) was repeatable at other laboratories. The program
also was designed to determine ways to improve repeatability. Six
engines which are newer models of engines tested under the SwRI
baseline program, were chosen to be tested by seven labs: Cum-
mins, Detroit Diesel Allison (DDA), International Harvester (IHC),
Caterpillar (CAT), Mack, SwRI, and EPA. Table 1 presents the test
plan for these engines. A total of 30 sets of tests were sched-
uled to be conducted on these six engines. Currently 77 percent
of these tests have been completed. By June 1, 90 percent of the
testing should to be complete, and the program will be completed
by July 1,1982.
This report will analyze all of the data currently available.
First, inter-lab variability will be discussed, followed by a
discussion of intra-lab variability. The correlation between
13-mode and transient particulate emissions will not be presented
in this report due to the limited amount of data available, but
will be reviewed in the final report.
II. Inter-Lab Variability
A. Transient Testing
Tables 2-4 present composite, cold start and hot start emis-
sion results for particulate, HC and NOx. Each lab conducted at
least 2 cold starts and 12 hot starts per engine. The inter-lab
variability (s/x) has been calculated for only those engines which
have been tested by more than two labs. Overall, the particulate,
HC and NOx variability has been quite acceptable at less than 10
percent with the exception of the Mack engine which has exhibited
signs of variability not associated with inter—lab variability
trends. Composite, cold start, and hot start variability are com-
parable, with NOx emission measurement appearing to have the least
variability. Initially, it was expected that there would be much
inter-lab variability for transient particulate emissions. How-
ever, an examination of the data to date does not bear this out.
The greatest variability for the HC emissions occurred with
the Mack and Cummins engines. The first set of data reported by
EPA for the Cummins engine was excluded from the inter-lab vari-
ability calculations because during testing by EPA the engine un-
knowingly developed a turbocharger oil leak. This leak was found
by DDA during their testing subsequent to EPA testing. It is
possible that HC results from the other test sites were affected
by this leak; this could be the reason for the high variability
for this engine. The engine completed a series of transient and
13-mode
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tests at EPA, with a replacement turbocharger installed, to verify
the above contention and has been shipped to Cummins for testing.
The variability of the Mack engine has been reviewed in an
earlier report and will not be discussed in this interim report.
In addition to transient composite and 13-mode steady-state
emission results, Tables 2 and 5 also include normalized data.
The data was normalized by dividing each laboratory's emission re-
sult by the mean value for the engine. Then the coefficient of
variation (s/x) for all of the normalized composite and 13-mode
data was calculated. This coefficient of variation is an indic-
ation of the degree of inter-lab variability associated with the
measurement of each emission. The overall variabilities for the
composite particulate, HC and NOx emission measurements are 8.7,
12.6, and 9.2 percent, respectively.
B. Steady-State Testing
The steady-state testing included NOx, HC and particulate
sampling over the 13-mode test and particulate sampling for modes
6 and 11 of the 13-mode test. These results are presented in
Table 5. In most cases results at each lab represent at least 2
tests. Once again the inter-lab variability for the Cummins en-
gine's HC and particulate emissions may have been high due to the
effect of the turbocharger oil leak.
The overall variability for the 13-mode particulate, HC and
NOx emission values are 16.7, 8.3 and 7.7 percent, respectively.
When comparing 13-mode and transient particulate emissions, it is
evident that the variability is 10 percent greater for the 13-mode
test. The variabilities between 13-mode and transient NOx and HC
emission measurements are approximately the same.
III. Intra-Lab Variability
Table 6 presents intra-lab variability for transient HC, NOx
and particulate emissions. The intra-lab variability for each lab
is expressed as the standard deviation divided by, the mean,
(s/x). The variability of NOx emission measurements is excellent,
ranging from 1.0 to 6.8 percent. Variability of HC measurement
ranges from 0.9 to 16.9 percent, while particulate measurements
range from 2.3 to 10 percent
IV. Summary
In summary, 73 percent of the testing from the EMA/EPA
cooperative test program has been completed. Six engines are
involved in this test program and are being tested by seven
different laboratories. Inter-lab variability for both transient
and 13-mode testing has been below 10 percent except for 13-mode
particulate which was on the order of 16.7 percent, and transient
HC at 13 percent. The NOx measurement appears to have the least
variability. When comparing 13-mode particulate emissions with
transient emissions, it appears that inter-lab variability is
greater for the 13-mode particulate emission. Variability between
13-mode and transient HC and NOx emissions are about the same.
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Intra-lab variability for NOx emission measurement was excel-
lent, averaging 3.3 percent. Intra-lab variability for HC and
particulate emissions are comparable with the average variability
for HC being 6.1 percent, and for particulate, 4.1 percent.
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References
1. "Diesel Hydrocarbon and Particulate Correlation
Status," Danyko, D., EPA, August 14, 1981.
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Table 1
Test Plan for EMA/EPA Cooperative Engine Test Program
No. of
Test Site Test Sets
Test Engine SwRI IHC CAT CUM MACK PDA EPA Per Engine
IHC DTI-466B 8/81 7/81 11/81 3/82 9/81 2/82 (4/82) 9
(5/82) (6/82)
CAT 3406 DITA 8/81 10/81 3
3/82
CAT 3208 DINA . 8/81 4/81 3
5/82
Cummins VTB-903 5/81 4/81 11/81 9/81 6
(5/82) (3/82*)
Mack ETSA-676 10/81 7/81 2/82 4
\ (4/82)
V
DDA 8V-71TA 8/81 5/82 9/81 1/82 6/81 _6
(6/82)
Engines Per Lab. 3254 33 3 31
* Retest at EPA due to turbocharger malfunction.
X/XX Date tests completed.
(X/XX) Date tests estimated to be completed.
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Table 2
EMA/EPA Cooperative Test Program
Transient Composite Emission Results (g/bhp-hr)
Particulate
Test Engine
1. Cummins VTB-903
Lab: Cummins
SwRI
EPA
DDA
X
s/x, %
2. Mack ETSA676
Lab: Mack
Caterpillar
EPA
X
x[l]
0.67
0.67
0.63
0.65
0.66
2.9
0.71
0.53
0.81
0.68
x/x[2]
1.02
1.02
0.95
0.98
1.04
0.78
1.19
s/x, % 20.8
3. IH DTI-466B
Lab: IHC
SwRI
Mack
Caterpillar
X
s/x", %
4. Cat 3208 DINA
Lab: Caterpillar
IHC
X
5. Cat 3406 DITA
Lab: Caterpillar
Cummins
X
6. DDA 8V-71TA
Labi DDA
SwRI
Cummins
X
s/x, %
Overall Average, x[3]
s/x, %, (Inter-lab
0.74
0.63
0.64
-
0.67
9.1
0.68
0.68
0.68
0.76
0.76
0.76
0.48
0.44
0.53
0.48
9.3
1.10
0.94
0.96
-
1.00
1.00
1.00
1.00
1.00
0.92
1.10
1.00
8.7
HC
X
1.69
2.24
2.01
1.91
1.96
11.6
0.85
0.73
0.57
0.72
19.6
0.99
0.87
0.91
0.99
0.94
6.4
0.95
1.32
1.14
0.58
0.39
0.49
0.74
0.63
0.69
0.69
8.0
x/x
0.86
1.14
1.03
0.98
1.18
1.01
0.79
1.05
0.93
0.97
1.05
0.83
1.16
1.18
0.80
1.07
0.91
1.00
.9967
12.6
X
5.63
5.57
4.92
4.87
5.25
7.8
6.32
6.82
8.54
7.23
16.1
3.86
4.41
3.97
4.44
4.17
7.1
7.95
7.66
7.81
4.7
4.7
4.7
7.38
7.91
7.90
7.73
3.9
NOx
x/x
1.07
1.06
0.94
0.91
0.74
0.94
1.18
0.93
1.06
0.95
1.06
1.02
0.98
1.00
1.00
0.95
1.02
1.02
.9906
9.2
Variability)
[1] The average emission measurement at a given lab.
[2] Normalized value.
[3] x of normalized values.
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Table 3
EMA/EPA Cooperative Test Program
Transient Cold Start
Test Engine
1. Cummins VTB-903
Lab: Cummins
SwRI
EPA
DBA
X
s/x, %
2. Mack ETSA676
Lab: Mack
Caterpillar
EPA
X
s/x, %
3. IE DTI-466B
Lab: IHC
SwRI
Mack
Caterpillar
X
s/x, %
4. Cat 3208 DINA
Lab: Caterpillar
IHC
X
5. Cat 3406 DITA
Lab: Caterpillar
Cummins
X
6. DDA 8V-71TA
Lab: DDA
SwRI
Cumimins
X
s/x, %
Particulate
X*
1.02
1.02
0.91
0.96
0.98
5.3
0.70
0.66
0.83
0.73
8.9
0.76
0.63
0.67
-
0.69
9.7
0.82
0.73
0.78
0.86
0.75
0.80
0.54
0.45
0.51
0.50
9.2
Emission Results
HC
X
2.79
4.42
3.65
3.41
3.57
18.9
0.99
0.80
0.64
0.81
21.6
1.26
1.18
1.21
1.12
1.19
4.9
1.25
1.71
"His"
0.64
0.43
0.54
0.78
0.74
0.72
0.75
4.1
NOx
x
3.87
4.59
3.93
4.42
"5720"
8.5
7.80
7.50
7.60
4.64
5.17
4.91
x = The average emission measurement at a given lab.
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Table 4
EMA/EPA Cooperative Test Program
Transient Hot Start
Test Engine
1. Cummins VTB-903
Labi Cummins
SwRI
EPA
DDA
X
s/x, %
2. Mack ETSA676
Lab: Mack
Caterpillar
EPA
X
s/x, %
3. IH DTI-466B
Labi IHC
SwRI
Mack
Caterpillar
X
s/x, %
4. Cat 3208 DINA
Lab; Caterpillar
IHC
X
5. Cat 3406 DITA
Labi Caterpillar
Cummins
X
6. DDA 8V-71TA
Labi DDA
SwRI
Cummins
X
s/x, %
Particulate
X*
0.63
0.61
0.54
0.58
0.59
6.6
0.66
0.56
0.76
0.66
15.2
. 0.75
0.63
0.66
-
0.68
9.2
0.66
0.70
0.68
0.72
0.77
0.75
0.47
0.44
0.54
0.48
10.6
Emission Results
HC
X
1.50
1.87
1.60
1.61
1.65
9.5
0.78
0.74
0.56
0.69
16.9
0.94
0.82
0.84
0.95
0789"
7.6
0.92
1.24
1.08
0.57
0.38
0.48
0.73
0.61
0.69
0.68
9.0
NOx
x
5.62
5.70
5.141
5.01
5.37
6.4
6.83
6.68
8.39
7.30
13.0
3.86
4.38
3.96
4.41
7715-
6.8
7.98
7.60
7.79
4.74
4.95
4.85
x = The average emission measurement at a given lab.
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Table 5
EMA/EPA Cooperative Test Program
Steady-State Emission Results
13-Mode Particulate 13-Mode HC 13-Mode NOx Mode-6 Part
Test Engine
1. Cummins VTB-903
Lab; Cummins
SwRI
EPA
DDA
x
s/x, %
2. Mack ETSA676
Lab; Mack
Caterpillar
EPA
x
s/x, %
3. IH DTI-466B
Lab; IHC
SwRI
Mack
Caterpillar
x
s/x, %
4. Cat 3208 DINA
Lab; Caterpillar
IHC
x
5. Cat 3406 DITA
Lab; Caterpillar
Cummins
x
6. DDA 8V-71TA
Lab; DDA
SwRI
Cummins
x
s/x, %
Overall x
s/x, %, (Inter-Lab
x*
0.44
0.38
0.44
0.33
0.40
(13.3)
0.40
0.69
0.44
0.51
30.8
-
0.53
0.35
-
0.44
0.61
0.50
0.56
0.72
0.66
0.69
0.23
0.25
0.19
0.22
13.7
x/x
1.10
0.95
1.10
0.83
0.78
1.35
0.86
-
1.20
0.80
-
1.22
0.89
1.04
0.96
1.05
1.14
0.86
1.01
16.7
x
0.81
0.95
0.94
0.84
0.89
(8.0)
0.58
0.52
0.48
0.53
9.5
0.68
0.77
0.86
0.63
0.74
13.8
0.97
0.97
0.97
0.34
0.32
0.33
0.63
0.68
0.55
0.62
10.6
X/X X
0
1
1
0
1
0
0
0
1
1
0
1
1
1
0
1
1
0
1
8
.93
.09
.06
.97
.09
.98
.90
.92
.04
.16
.85
.00
.00
.03
.97
.02
.10
.89
.00
.3
6.07
6.39
4.84
6.36
5.92
(12.4)
6.25
8.14
6.83
7.07
13.7
4.14
3.86
3.51
4.13
3.91
7.6
8.13
7.97
8.05
5.01
5.0
5.0
8.73.
8.97
8.88
8.85
1.6
X/X X
1.03
1.08
0.82
1.07
0.88
1.15
0.97
1.06
0.99
0.90
1.06
1.01
0.99
1.00
1.00
0.99
1.01
1.00
1.01
7.7
0.24
0.29
0.25
0.23
0.25
(10.5)
-
1.35
1.74
1.55
-
0.51
-
-
0.52
0.66
0.59
0.98
0.79
0.89
0.25
0.22
0.23
0.23
6.5
x/x
0.96
1.16
1.00
0.92
-
- ' •
-
-
-
-
0.88
1.12
1.10
0.89
1.09
0.96
1.00
1.01
9.6
. Mode-11 Part.
x
0.72
0.77
0.74
0.71
0.74
(3.6)
-
0.79
0.50
0.65
-
0.95
-
-
1.00
0.96
0.98
1.1
1.02
1.06
0.32
0.38
0.33
0.343
9.4
x/x
0.99
1.05
1.00
0.97
-
-
-
- .
- —
-
,
~*^
1.02
0.98
1.04
0.96
0.93
1.12
1.00
1.00
5.1
variability)
x = The average emission measurement at a given.lab.
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Table 6
EMA/EPA Cooperative Test Program
Test Lab
Test Engine
Cummins
DDA
Cat 3406
Cat 3208
Mack
IH
Test Lab
Test Engine
Cummins
DDA
Cat 3406
Cat 3208
Mack
IH
Test Lab
Test Engine
Cummins
DDA
Cat 3406
Cat 3208
Mack
IH
Curamins
16.9
2.4
Intra-Lab Variability
Transient Testing
HC Emissions Variability,
DDA Cat Mack
6.8
1.9
8.8
6.5
2.0 8.5
3.5 6.9
(s/x, %)
IHC SwRI
5.0
16.4
4.0
5.3 3.1
EPA
0.9
13.8
Particulate Emissions Variability, (s/x, %)
Cummins
3.5
2.6
Cummins
1.2
1.0
DDA Cat Mack
8.6
3.3
5.6
3.0
10.5 3.0
6.2
NOx Emissions Variability,
DDA Cat Mack
2.6
1.2
1.9
3.1
2.3 5.7
1.9 4.2
IHC SwRI
2.9
2.3
10.0
4.0 2.6
(s/x, %)
IHC SwRI
3.9
1.9
3.8
4.5 1.5
EPA
3.0
4.6
EPA
2.9
6.8
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