73-9
A Second Evaluation
of the
Questor Emission Control System
November 1972
Thomas C. Austin
Test and Evaluation Branch.
Division of Emission Control Technology
Environmental Protection Agency
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Background
EPA recently performed a short evaluation of a
vehicle prepared by Questor Automotive Products of
Toledo, Ohio. The vehicle equipped \vith the Questor
"Reverter" emission control system had been available
only long enough for one 1975 Federal Test Procedure
to be run. Because of the impressive emission levels
recorded during the first EPA test (below 1976 require-
ments) a decision was made to perform a more extensive
evaluation at a later date.
Approximately 4,000 miles had been accumulated
on the Questor vehicle since the first test. Total system
mileage was approximately 8,000 at the beginning of this
test series. Questor representatives claimed that all
of the mileage had been accumulated using highly leaded
fuels. A lead determination, performed by EPA, on a
sample of fuel from the vehicle's tank indicated a lead
content of 2.5 grams per gallon.
Vehicle Tested j
I
The Questor "Reverter" emission control system was
installed on a 1971 Pontiac Catalina equipped with a 400
CID V-8 engine, automatic transmission and air conditioning.
The heart of the system is a pair of non-noble reduction
catalysts sandwiched between partial thermal reactors.
Carburetor calibration and exhaust port air injection
rates are set such that a reducing atmosphere is still
present after the exhaust gas passes through.the first
partial thermal reactor stage. After the exhaust gas
passes through the NOX catalyst, additional air is added
to complete combustion of the HC and CO remaining. Exhaust
gas recirculation (EGR) is not used.
One "reverter" is used on each bank of a V-8 engine.
Figure 1 is an illustration of a reverter attached to a
cylinder head. "Limited oxidation" and "final oxidation"
takes place in the partial thermal reactors. The "reduction
zone" houses the expanded metal NOX catalyst. Figure 2
shows a cut-away reverter system installed on a cylinder
head. As can be seen from the picture, the construction
is double walled to reduce heat loss.
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The vehicle's exhaust system is constructed of
double walled pipe. Air pump discharge is routed
to the rear of the vehicle and pumped into the
annular cavity surrounding the inner exhaust pipe.
The air is then heated by the hot inner pipe as it is
pumped toward the front of the vehicle where it is
removed from the annular cavity and injected into the
partial thermal reactors at 800° F.
Incorporated in the Questor vehicle is a sub-system
to improve fuel economy and reduce system temperatures
during high load operation. This system, designated
"Normal Operating Temperature Control (N.O.T.C.)" senses
both load and time. When the vehicle is exposed to a
high enough load for a long enough period of time a
portion of the air pump discharge is diverted to the
intake manifold, causing enleanment of the mixture.
The system is activated when two separate chambers are
pressurized by a portion of the air pump discharge.
The time required to pressurize the chambers depends
on the air pump speed (a function of vehicle speed) and
the exhaust backpressure (a function of vehicle load).
Normally at loads below those required for a 50 mph
cruise the system will never activate because the air
pump discharge cannot overcome the built-in leakage
in the chambers. Above 50 mph the system will only
activate if the driver maintains a steady throttle
position and does not use his brakes. Brake application
causes one of the volumes to dump immediately.
As adjusted on this vehicle the N.O.T.C. system
would only be activated during expressway or highwav
operation in light traffic. Activation causes a
considerable loss in NOX control but good HC and CO
control is maintained. Our previous testing of the
Questor vehicle indicated that fuel economy of better
than 15 miles per gallon could be achieved at 60 mph
cruise with the system activated.. Properly calibrated
the system would not be activated in heavy traffic
situations or stop and go driving. As installed on the
vehicle tested, the N.O.T.C. system ivas fully adjustable.
A production version would use fixed orifices rather than
adjustable valves. The system was never activated during
the LA-4 driving cycle of the Federal Test Procedure.
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Test Program
The Questor vehicle was tested using the 1975
Federal Test Procedure with two different vehicle
weights simulated. Two tests were run at a 5,00^
pound test weight, the "correct" test weight for the
full size Pontiac and two tests were run at a reduced
weight of 3,nnn pounds simulating a compact vehicle.
A description of the Federal Test Procedures is enclosed
(Attachment I).
In addition to the gaseous emission tests, the
vehicle was also tested for particulate emissions. The
particulate testing was done by Dow Chemical of Midland,
Michigan through an existing EPA contract. The Dow
procedure simulates an air ciuench of the vehicle's
exhaust gas by routing the exhaust into a 15-7/8 inch
diameter tube where it is diluted to a 500 cfm floxtf.
Twenty-seven feet downstream of the tailpipe samples
are pulled from the diluted exhaust through fiberglass
filters, millepore filters and'an Anderson impactor.
Only the particulates still in suspension are captured.
While the Dow procedure is not necessarily going to end
up as a Federal Procedure, it does allow us to compare
particulate emission levels from different vehicles using
a common procedure.
Test Results
Results are summarized in Tables I and II. Table
I lists gaseous emission test results using the 1975
Federal Test Procedure for test weights of both 5,0^0
and 3,000 pounds. Emissions were under the 1976 levels
during each test. Hydrocarbon control was very good.
During the only test above .03 grams per mile HC (16-0023)
the vehicle did not restart well after the ten minute
soak. NOx control was quite good. A 40% reduction in
test weight from 5,000 pounds to 3,000 pounds caused a
36% reduction in NOX levels. CO levels were much
lower than normally expected from vehicles using thermal
reactors to control CO.
Fuel economy at 5,000 pounds test weight averaged
6.93 miles per gallon. This represents a 20% penalty
compared to the average of all 1973 certification proto-
types tested by EPA during the spring and summer of 1972.
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(Corrections were made for the slight difference
in test procedure.) The fuel economy improvement
measured when the test weight was lowered to 3,000
pounds was not very large because the carburetion,
engine size, and driveline were poorly matched for
a lighter weight application.
Results of the particulate testing are listed in
Table II. At 60 mph steady state the particulate levels
were comparable to a vehicle using 0.5 grams per gallon
lead fuel. An EPA lead determination run on the gasoline
used during the Ouestor testing indicated a lead level of
2.87 grams per gallon. A conventional (1970 production
Chevrolet) run with 3.0 gram fuel emitted particulate
levels over four times greater than the Questor vehicle.
More data points will be required to lend significance
to the results.
Conclusions
1. The Ouestor emission control system can achieve
the 1976 Federal emission levels at low mileage. Durability
is yet to be demonstrated. '
2. The Questor system causes a considerable (=s20%)
loss in fuel economy in stop and go driving. There
appears to be, however, potential for reducing this
penalty by modulating air injection as a function of
engine load which would allow leaner calibration.
3. Particulate emission levels from the Ouestor
system appear to be lower than those from conventional
systems using leaded fuels. Future testing will be
required to verify the preliminary results.
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TABLE I
Questor Emission Control System
1975 Federal Test Procedure
(emission data in grams per mile)
5000# Test Weight
Test Number
16-0023
16-0033
Average
Test Number
16-0029
16-0034
Average
HC
23 .
01
12
Weight
HC
03
02
03
CO
2.J55
1/98
2.27
-•
00
1.66
2.55
2.11
NOY
.34
.31
.33
NOy
.22
.20
.21
mpg
6.89
6J96
6.93
mpg
7.73
7.70
7.72
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TABLE II
Particulate Emissions
(all data in grams per mile)
Hot Start 60
Vehicle Fuel 72 FTP steady state
Questor 101 2.87 gpg Pb .15 .025
1971 Chevrolet .5 gpg Pb - .021
1970 Chevrolet 3.0 gpg Pb - .110
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CHEMICAL PROCESS
1: LIMITED OXIDATION ZONE
M-MWV.
2: REDUCTION ZONE
3: FINAL OXIDATION ZONE
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REVERTER PROCESS
•\UESTOR
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ATTACHMENT I
FEDERAL EMISSION TESTING PROCEDURES
FOR LIGHT DUTY VEHICLES
The Federal procedures for emission testing of light
duty vehicles involves operating the vehicle on a chassis
dynamometer to simulate a 7.5 mile (1972 procedure) or
11.1 mile (1975 procedure) drive through an urban area.
The cycle is primarily made up of stop and go-driving and
includes some operation at speeds up to 57 mph. The
average vehicle speed is approximately 20 mph. Both the
1972 and 1975 procedures capture the emissions generated
during a "cold start" (12-hour soak @ 68°F to 86°F before
start-up). The 1975 procedure also includes a "hot start"
after a ten minute shut-down following the first 7.5 miles
of driving. •
Vehicle exhaust is drawn through a constant volume
sampler (CVS) during the test. The CVS dilutes the vehicle's
exhaust to a known constant volume with make up air. A
continuous sample of the diluted exhaust is pumped into
sample bags during the test. -~
Analysis of the diluted exhaust collected in the sample
bags is used to determine the mass of vehicle emissions per
mile of operation (grams per mile). A flame ionization de^
tector (FID) is used to measure unburned hydrocarbon (HC)
concentrations. Non-dispersive infrared (NDIR) analyzers are
used to measure carbon monoxide (CO) and carbon dioxide (C02).
A chemiluminescence (CL) analyzer is used to determine oxides
of nitrogen (NOx) levels.
These procedures are used for all motor vehicles designed
primarily for transportation of property and rated at. 6,000
pounds GVW or less, or designed primarily for transportation of
persons and having a capacity of twelve persons or less. Each
new light duty vehicle sold in the United States in model years
1973 and 1974 must emit no more than 3.4 gpm HC, 39. gpm CO'
and 3.0 gpm NOx when using the 1972 procedure. In 1975 the
standards will change to .41 gpm HC. 3.4 gpm CO and 3.1 gpm NOx
using the 1975 procedure. In 1976 the standards will be .41
gpm HC, 3.4 gpm CO and .4 gpm NOx using the 1975 procedure.
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