71-22
Exhaust Emissions From An Army M-151 Equipped With A
Mitsui Catalyst
March 1971
John C. Thomson
Mobile Source Pollution
Air Pollution Control Office
ENVIRONMENTAL PROTECTION AGENCY
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Vehicle Tested
A standard Army 1/4 ton M-151 vehicle was tested for exhaust
emissions before and after installation of a Mitsui Catalytic
exhaust reactor. This vehicle uses a 141 cubic inch, inline,
four cylinder engine and requires an inertia weight of 3000
pounds. For these tests the reactor was installed in place
of the standard muffler with an auxiliary air line provided
to supply air for the reactor and an exhaust by-pass to pre-
vent overtemperature in the reactor. The air was supplied by
a shop air system and flow was varied from 1.2 cubic feet
per minute '(cfm) at idle to 1.8 (cfm) at cruise with 3.6 (cfm)
during acceleration.
Tests Conducted
The vehicle was tested using the following test procedures:
1. The 1972 Federal test procedure using the LA4-S4
driving cycle (LA4).
2. The standard 1970 Federal test procedure for exhaust
emissions (FTP).
During the FTP tests, oxides of nitrogen were taken continuously
using an infrared detector.
Results
When the catalyst was first received it was installed on
the Army vehicle and tested on the LA4 driving cycle. Tempera-
ture was continuously monitored to prevent over temperature of
the catalyst. After about 10 minutes of operation, the tempera-
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ture exceeded a previously determined level, of 1150°F and
the test was halted. The temperature in the reactor, however,
continued to rise and eventually liquid C02 was used to cool
the reactor and prevent melting of the reactor case.
In order to reduce the chance of exceeding the temperature
in the second set of tests, a by-pass system was constructed
to allow the catalyst to cool if high temperatures were
reached. The catalyst was tested under these conditions and
the results are reported in Tables 1, 2 and 3. These results
are compared to tests run using the same exhaust and the same
vehicle but without catalyst. .The catalyst temperature is
i
reported in Table 1 during each cycle.
At the conclusion of these tests on the open cycle FTP, a
second LA4 was attempted. During this test the catalyst again
overheated even though the by-pass system was open to reduce
the temperature. The test was stopped at 1200°F but the
temperature continued to rise to 1450°F with all air to the
catalyst stopped.
Conclusions
The catalyst showed reductions after it reached temperature
but achieving the temperature took a long time.
The overtemperature problem appears to be the catalyst beginning
to burn at a temperature below the maximum rated temperature
of the catalyst. The most effective temperature for reduction
appears to be near the maximum temperature of the catalyst.
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Table 1
Hydrocarbon Comparison Data
M-151
Cycle 1
Cycle 2
Cycle 3
Cycle 4
Cycle 6
Cycle 7
Mode 1
Mode 2
Mode 3
Mode 4
Mode 5
Mode 6
Mode 7
Standard
ppm
2000
327
394
298
319
136
348
212
492
221
201
1764
Mitsui
ppm
919
339
254
221
182
•
67
130
124
145
105
99
359
Temperature
oF
300
500
1000
1000
1100
Total
305
143
1100
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Table 2
Carbon Monoxide Comparison Data
M-151
Standard Mitsui
Cycle 1
Cycle 2
Cycle 3
Cycle 4
Cycle 6
Cycle 7
Mode 1
Mode 2
Mode 3
Mode 4
Mode 5
Mode 6
Mode 7
4.96
3.44
4.35
3.93
3.97
I
i
2.09
4.04
4.98
3.36
5.71
4.04
4.01
7.17
3.17
3.43
3.24
2.20
0.29
2.04
2.25
0.82
2.24
1.76'
0.79
Total 4.17 2.04
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Table 3
Oxides of Nitrogen Comparison Data
M-151
Standard Mitsui
ppm ppm
Cycle 1 670 464
Cycle 2 868 848
Cycle 3 778 780
Cycle 4 666 . 546
Cycle 6 605 631
Cycle 7
i
Mode 1 140 . | 128
Mode 2 550 '. 443
Mode 3 428 523
Mode 4 178 302
Mode 5 203 243
Mode 6 741 620
Mode 7 295 295
Total 566 577
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