71-21
Exhaust Emissions From a Reactor Equipped, Full-Sized
Automobile Using LPG Fuel
March 1971
John C. Thomson
Division of Emission Control Technology
Mobile Source Pollution Control Program
Air Pollution Control Office
ENVIRONMENTAL PROTECTION AGENCY
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Vehicle Tested
A specially equipped 1971 Oldsmobile Delta 88 was supplied
by General Motors for evaluation by APCO. This vehicle
was to have very low exhaust emissions, approaching the
1975 levels. A Century LPG Conversion Kit was used with
modifications made to provide low emissions. In addition,
a reactor, exhaust gas recycle and a pulse air injection
system were supplied. All vehicle tests were made using
the fuel supplied by GM and no attempt was made to analyze
the fuel composition. .
Tests Conducted
The following tests were performed on the vehicle:
1. Standard 1970 Federal test procedure for
exhaust emissions (FTP).
2. Closed, constant volume sampling technique
using nine repeats of the Federal emissions
test cycle (9x7). .
j
3. Closed, constant volume $amp~ing technique
using the LA4-S4 driving schedule as developed
for 1972 and later new vehicle certification
(LA4) .
Bag samples taken during closed cycle tests were analyzed
using non-dispersive infrared analysis (IR) for carbon
monoxide and catbon dioxide, flame ionization detection
(FID) was used for hydrocarbon analysis. In order to com-
pare oxides of nitrogen measurements with data taken on
other vehicles, a variety of techniques were used. A
modified Saltzman (Saltz) technique was used for wet chemi-
cal analysis, a chemiluminescent technique (CI), and an
electrochemical (ENVTS) technique were also used. All
results are reported as N02 and have been corrected for
humidity using the following: .
N02 measured
. . .
N02 corr =
1-0.0047 (H-75)
where H is the humidity in grains of water.
When open cycle tests were run, npn-dispersive infrared
oxides of nitrogen data were taken.
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Emission Results
All of the data taken during the test period can be found
in Tables 1 and 2. After the first test shown in Table 1,
the carburetor \vas adjusted to improve drive.abili ty. The
hydrocarbon values were consistantly higher than .the pro-
posed 1975 standards of 0.46 gpm while carbon monoxide was
lower than the standard of 4.7 gpm except on the last test.
No standard for oxides of nitrogen has been adopted, how-
ever, the values shown on these tests are very low. The
hydrocarbon values would probably be reduced if a density
for hydrocarbon in the exhaust had been determined and used
in place of the standard density for gasoline. The results
fell in the low ranges of the instruments used and the exact
numbers may be questionable, although repeatability was good.
Background hydrocarbon levels were quite high on some tests
and may have influenced levels also.
Conclusions
The vehicle
attempts to
runs.
showed low emission levels.
measure driveability except
!
~
There were no
for acceleration
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Table 1
HC CO C02 NOx NOx NOx
Date (FlD) (NDlR) (NDlR) (Saltz) (Cl) (ENVTS)
LA4-S4 Test Results (gpm) *
2/09 1.0 1.3 984 .0.3 0.4 0.6
2/11 1.0 2.9 952 0.4 0.4 0.8
2/16 0.6 5.0 981 0..4 0.1
9x7 Test Results
2/12 0.6 1.4 905 0.6 0.2 0.6
* Results obtained using HC density of 16.33 and no
correction for reactivity or fuel composition. The
effect 6f density correction would be less than 10%.
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TABLE 2
'1970 Federal Test Procedure (FTP)*
HC CO NO
Cycle ppm ppm ppm
1 280 0.08 92
2 61 0.02 100
3 44 0.02 106
4 36 0.02 100
6 45 0.02 100
7 40 0.01 102
Composite .93 gpm .61 gpm .45 gpm
* Results obtained using standard
method with no correction for fuel
type, reactivity or instrument re-
sponse.
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