EPA-AA-TEB 71-32
Emissions From Two LPG Powered Vehicles
February 1970
Michael A. Caggiano
Division of Motor Vehicle Pollution Control
National Air Pollution Control Administration
Department of Health, Education, and Welfare
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Subject: Results of evaluations on vehicles run on LP-Gas
An evaluation of the emissions from two vehicles, equipped
to run on LP-Gas, has been completed. The two vehicles were:
a) A 1968 Buick Skylark, 350 CID automatic transmission
and the Impco "300 A" LP-Gas carburetor. This vehicle
was supplied by George Leek of Cities Service Oil Company.
b) a 1969 Ford Galaxie, 351 CID automatic transmission,
and Algas MX500 LP-Gas carburetor. This vehicle was
also equipped to run on gasoline. The National LP-Gas
Association provided this car.
The evaluation consisted of:
a) Simultaneous collection and measurement of exhaust
by the 1970 Federal Procedure and Constant Volume
Sampling (CVS) Procedure (nine 8-mode cycles). Both
cold and hot start tests were run.
b) Measurement of oxides of nitrogen content of the
sample bag from CVS using the Saltzman technique.
c) Reactivity measurement of exhaust using subtractive
column analysis of CVS sample bag.
d) Qualitative assessment of vehicle driveability by
several staff personnel.
A summary of results is included in the attached tables.
The results of the emissions measurements indicate that there
is, as expected, a substantial reduction in carbon monoxide
emissions, when compared to a similar gasoline fueled engine.
The Ford showed a significant reduction in hydrocarbon emissions
when switching from LP-Gas to gasoline. No such comparison
was possible with the Buick. Included in Table I are some
data from two NAPCA surveillance vehicles with similar engines
to the ones run on propane. .The hydrocarbon levels obtained
with LP-Gas vehicles are not impressive when compared to the
surveillance vehicle hydrocarbon levels.
Based on the subtractive column data, the hydrocarbons emitted
from a propane fueled engine are less reactive due to the
lower olefin and aromatic content of the exhaust.
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The oxides of nitrogen (NOX) output is higher with propane
as the fuel, perhaps as much as 50 percent higher.
While using the subtractive columns we noticed that it took
much longer for the column removing the olefins to reach
equilibrium than the cycle timer allowed. This suggests that
it would be wise to use a recorder with the FID and to
manually control the time spent in each cycle.
When comparing the CVS data with the data from the 1970
procedure for the two cars, the Buick is better than the Ford
by 1970 Procedures but the same or slightly worse by CVS.
This could be due to the two speed automatic in the Buick or
simply that the Buick has higher emissions than the Ford in
the modes not measured by the 1970 Procedure.
The dilution and reactivity factors used in the 1970 procedure
calculations are those used by the State of California, i.e.
for propane;;
i ->
Correction Factor =
% CO2 + (0.5)% CO + (1.8 x 6) HC
reactivity factor =0.75
The staff generally agreed that the driveability of both cars .
was good. In cold "drive-away" these cars are probably
superior to current vehicles. Power loss, was insignificant.
We had an opportunity to cold start the Buick Skylark at
ambient temperatures below 20° F. In these cold starts the
Buick started at least as well as gasoline fueled vehicles.
In summary, based on these vehicles and the tests performed,
LP-Gas fueled .engines when compared to similar gasoline fueled
engines are:
HC ; CO NOX Reactivity
perhaps better much better worse better
It should be stressed that time and manpower limitations did
not permit determining that these engines were in the optimum
state of tune for LP-Gas. Therefore, this data cannot be
interpreted as the best that can be expected from an LP-Gas
fueled vehicle. It is indicative of the kind of emissions
obtained from a simple conversion from gasoline to LP-Gas as
the motor fuel.
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TABLE
Vehicle
Buick
Ford
it
Test
Cold Start
n ti
Hot Start
Cold Start
n n
Hot Start
Summary of Results
Ford -
30-Cruise
40-Cruise
using gasoline
Cold Start 7.36
CVS
HC
(FID)
Procedure
CO
NOX
grams/mile
3.56
3.34
3.08
2.95
3.12
3.09
2.91
2.70
2.69
2.31
2.09
5.43]
4.22
4.15
5.26
6.40
8.32
8.17
5.97
6.76
2.02
1.48
9.5
8.4
7.4
7.5
_ —
8.6
8.4
9.4
9.3
7.5
1970
HC
PPM
171*
164*
225*
221*
Federal
CO
Procedure
HC
CO
% grams /mile
.154
.175
.243
.274
2.17
2.09
2.85
2.80
3.
4.
5.
6.
66
16
80
52
37.77
5.2
309
.95
1969 Surveillance Fleet Vehicles
Buick - Skylark - 350 CID
Cold Start
Hot Start
Ford - Fairlahe — 351 CID (3500 pound Inertia)
Cold Start 251
.52
3.91
2.90
22.67
CID
110 .81
1.92 29.60 4.0 102 .85
1.39 19.20
1.30 20.16
11.30
* Corrected using California dilution and reactivity factors.
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TABLE II
Exhaust Hydrocarbon Composition
by Subtractive Column Analysis
Parafins & .
Vehicle Test _ Benzene j Olefins Aromatics
% of Total Hydrocarbons
LP-Gas Buick Cold Start 74.5 25.5 0
" Hot Start 73.0 24.7 2.3
Standard 1969 Buick Hot Start 30 47.5 22.5
LP-Gas Ford Cold Start 72 22 6
11 ..i, 59 29 12
" Hot Start 67 27 6
57 .26.6 16
30-Cruise 63.5 22 14.5
11 " 40-Cruise 51.6 30 18.4
on Gasoline Ford Cold Start 40 36.4 23.6
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