EVAP 76-5
Technical Support Report for Regulatory Action
Automotive Industry Effort
to Comply with a 2.0 g/test
Evaporative Emission Regulation
by
Michael W. Leiferman
December, 1976
Notice
Technical support reports for regulatory action do not neccessarily
represent the final EPA decision on regulatory issues. They are inten-
ded to present a technical analysis of an issue and recommendations
resulting from the assumptions and constraints of that analysis. Agency
policy constraints or data received subsequent to the date of release of
this report may alter the recommendations reached. Readers are cautioned
to seek the latest analysis from EPA before using the information contained
herein.
Standards Development and Support Branch
Emission Control Technology Division
Office of Mobile Source Air Pollution Control
U.S. Environmental Protection Agency
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Automotive Industry Effort to Comply with a
2.0 g/test Evaporative Emission Regulation
Introduction
On Jaunary 13, 1976, a Notice of Proposed Rule Making (NPRM) for
evaporative emission from 1978 and 1979 model year light duty vehicles
and trucks was published in the Federal Register (Vol. 41, No. 8). This
publication proposed an evaporative emission standard of 6.0 g/test for
the 1978 model year and 2.0 g/test standard for the 1979 model year.
Comments on the NPRM were received from 13 automotive manufacturers,
These comments contained a modest amount of data from test work con-
ducted in attempt to achieve low evaporative emission levels. Some of
the submitted test results were below 2.0 g/test, and several tests
closely approached this level of control.
In June 1976 a report by Exxon Research and Engineering Company
on evaporative emission control was published. This report described
a test program in which six production vehicles were modified in order
to lower evaporative emissions. In the final modified configuration,
each of these vehicles had an evaporative emission level of less than
2.0 g/test.
On September 1, 1977 (approximately six months after comments had
been received on the NPRM) letters were sent to the automotive manufac-
turers who had commented on the evaporative NPRM. This letter requested
up-to-date information regarding their efforts in meeting the proposed
2.0 g/test level of control. The manufacturers were asked to submit
test data and information on control system configurations and cost.
Manufacturers from which this information was requested were:
American Motors
British Leyland
Chrysler
Fiat
Ford
General Motors
International Harvester
Mercedes-Benz
Nissan
Toyo Kogyo
Toyota
Volkswagen
Volvo
"Investigation and Assessment of Light-Duty Vehicle Evaporative
Emission Sources and Control", P.J. Clarke, EPA-460/3-76-014.
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Test Results and Cost Information
Of the thirteen manufacturer's which were asked for recent evapora-
tive emission control information, responses were received from seven.
These seven were British Leyland, Chrysler, Ford, General Motors, Toyo
Kogyo, Toyota, and Volvo. Of these seven responses, two (General Motors
and Toyo Kogyo) contained no test data. GM stated that they were encoun-
tering previously unknown problems in regard to meeting the 1978 evapora-
tive standard at high altitude. Their development efforts have been
concentrated in that area and they could not add significantly to the
data previously submitted. Similarly, Toyo Kogyo stated that they have
been occupied with development of systems to meet the 6.0 g/test standard
for 1978.
Test information which was submitted by the other five manufacturers
is contained in Appendix A as Attachments A-I through A-V. Attachment A-I
contains results of sixteen development tests conducted by Chrysler on
stock and modified 1978 California prototype control systems. As shown,
the nine tests conducted on passenger cars with non-stock systems ranged
from 2.04 to 5.55 grams. It appears that controlling emissions from
vehicles with larger fuel tanks is more difficult, since the three
vehicles tested with large fuel capacity (36 to 41 gallons) had emissions
ranging from 7.14 to 22.01 grams.
Data submitted by Ford is contained in Attachment A-II. Tests on
21 vehicles are presented, and six of these had average evaporative
emissions of less than 2.0 g/test. All 21 vehicles were equipped with
the 1978 production evaporative control system, which has a design level
of 3.0 g/test.
Attachment A-III is a list of the test results submitted by Toyota.
The emission levels are average values for five vehicles designed to
meet the 1978 6.0 g/test standard. As shown the vehicle averages range
from 2.8 to 4.8 g/test. Toyota estimates that the cost increase for
these evaporative control systems will range from $10.75 to $14.75 per
vehicle on all engine types except one. For that engine they will also
use an underhood ventilating fan which costs another $25.
Attachment A-IV contains the data supplied by Volvo. These vehicles
were all equipped with the production continuous fuel injection system.
As shown, a substantial reduction in evaporative emissions was achieved
by reducing the fuel tank pressure. The 1977 production system has a
fuel tank to charcoal canister pressure relief valve with a setting of
24 kPa (3.5 psig). When this valve was removed, the maximum fuel tank
pressure encountered during testing was 3 kPa (0.4 psig) and all of the
four vehicles tested at low altitude had evaporative emissions less than
2.0 g/test. Interestingly, removal of the pressure relief valve on the
one vehicle tested at high altitude (approximately 5300 ft) increased
evaporative emissions significantly. As shown in Attachment A-IV, use
of a larger canister and increasing the canister purge rate on the Volvo
vehicles reduced evaporative emissions. In regard to cost, Volvo stated
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that use of a differently calibrated tank pressure relief valve and
increasing the purge rate would be no cost modifications. Increasing the
canister capacity by 66% would cost an estimated $2.50.
Attachment A-V contains the data submitted by British Leyland.
These are carbureted vehicles. In current production configuration,
vehicle type A appears to emit less than 2.0 g/test.
Discussion
The data and comments received from the manufacturers indicate that
very little effort has been directed at developing systems targeted at
evaporative emission levels of 2.0 g/test.
The low level of effort which has been directed toward achieving
evaporative levels under 2.0 g/test is best exemplified by General
Motor's response, which contained no data. GM stated that background
emissions are still a real problem and a better solution than that
currently offered is needed. GM also indicated that certain types of
evaporative control systems may result in unsafe vehicle operation.
They state that seals used to stop carburetor vapor leaks might cause
throttle sticking and choke binding, and development programs must be
implemented to eliminate any such problems. GM states, "We believe that
the performance of 1978 model vehicles must be addressed before determin-
ing the need and cost/effectiveness of additional evaporative emission
control."
Ford also did not submit any data on vehicles which were designed
or modified in an attempt to meet a 2.0 g/test evaporative emission
level. However, Ford did state that they are currently engaged in a
program to determine whether available technology could support a 2
g/test standard. This program consists of establishing background
levels, establishing emission levels and sources from their 1978 control
systems, and developing systems to totally eliminate evaporative losses.
Currently, background tests are being conducted and system components
are being designed and procured. Ford states that they plan to finish
this program by about March, 1977.
Along with their test data, Chrysler stated that their efforts have
been devoted almost exclusively to the development of systems to meet
the 1978 evaporative standard. In the course of that development program,
they have discovered no new technology which would enable them to achieve
a 2 g/test level.
Like GM and Chrysler, Toyota, Toyo Kogyo and British Leyland stated
that they have been concentrating their efforts on establishing evapora-
tive emission control systems capable of meeting the 6 g/test standard.
Toyota stated that they are now planning to reinvestigate the structure
of their canister and the possibility of using the air cleaner for vapor
storage.
Because of the fuel injection system on their vehicles, Volvo
appears to have the evaporative emission problem quite well in hand.
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Their current equipment development and testing consists of improving
leak tightness of ECS and FI systems, determining an optimum fuel tank
pressure relief setting, and determining optimum canister size and purge
rate.
Summary
Since receiving comments on the 1978-79 evaporative emission NPRM,
it appears that there has generally been very little manufacturer develop-
ment effort targeted to meet a 2.0 g/test evaporative emission level.
By letter, thirteen manufacturers were asked to supply up-to-date infor-
mation regarding their efforts since the evaporative NPRM comment submittal.
Seven of these manufacturers responded. Of these seven only one domestic
manufacturer (Ford) stated that it was engaged in a development program
aimed at designing a control system which would meet a 2.0 g/test standard.
To date, Ford hasn't conducted any vehicle tests in this program.
However, Ford's tests on 21 vehicles equipped with the 1978 control
system did show that six of these vehicles had evaporative levels less
than 2.0 g/test.
One foreign manufacturer (Volvo) is doing development and testing
to achieve very low evaporative levels. Largely due to the configura-
tion of their engine fuel system (fuel injection) they have been success-
ful in achieving evaporative levels less than 2.0 g/test on all five
vehicles on which they have submitted test data.
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Appendix A - Test Data
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Test
Number
47-76
49-76
184-76
243-76
141-76
416-76
317-76
57-76
364-76
197-76
365-76
438-76
Stock
External Bowl Vent
Stock*
External Bowl Vent
Stock*
External Bowl Vent.
Carter Carb.
High Purge Rate.
Bowl Vent.
Hoiley Carb.
High Purge Rate.
Stock*
External Bowl Vent
2-Way Bowl Vent
2-Way Bowl Vent.
High Purge Rate.
2-Way Bowl Vent.
High Purge Rate.
Vapor Volume Storage.
TABLE 1
1976 CHRYSLER EVAPORATIVE
SYSTEM DEVELOPMENT TESTS TO DATE
Attachment A-I
Chrysler Data
Prototype
Emission
Conclusions
Baseline
Good
Baseline
Adequate
Baseline
Adequate
Barely Adequate
Baseline
Adequate
Not Adequate
Adequate
Car.
F6W
F610
F610
F610
B536
B536
B536
F235
F235
B202
B202
Enq.
225-1
225-1
225-2
225-2
318-2
318-2
318-2
360-2
360-2
360-4
360-4
Package
1978 California
1978
1978
1978
1978
1978
1978
1978
1978
1978
1978
California
California
California
California
California
California
California
California
California
California
Total
12.75
2.
13.
3.
11.
3.
4.
6.
3.
5.
3.
04
23
53
83
22
74
28
33
55
46
Hot
Soak
12.24
0
12
1
11
1
3
5
1
3
2
.98
.42
.79
.32
.97
.77
.69
.58
.51
.03
Diurnal
0
1
0
1
0
1
0
0
1
1
1
.51
.06
.81
.74
.51
.25
.97
.59
.75
.98
.43
Adequate
C593
440-4
1978 California
3.36
1.50
1.86
*Stock is prototype 1978 California exhaust
emission system with 1977 "carryover"
evap. emission system.
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TABLE 1
Test
Number
455-76
Hardware
Changes Conclusion
External Bowl Vent. Not Adequate
Hi ah PiirciR Rate.
Cont.
Car Enq.
L554 1:7
liters
Emission
Package
1978 California
Total
4.44
Heat Shields.
Special Canister.
468-76 2-Way Bowl Vent.
High Purge Rate.
Vapor Storage Volume.
462-76 External Bowl Vent.
High Purge Rate.
Vapor Storage Volume.
469-76 External Bowl Vent
Intersecting
Vapor Storage Volume.
Hot Adequate D328
Hot Adequate D261
Hot Adequate B296
360-2 1978 California
41 Gal.
Dual
Tanks
225-2 1978 California
36 Gal.
360-2 1978 California
36 Gal.
Hot
Soak Diurnal
3.00
1.44
22.01 5.74 16.27
7.14 3.04 4.10
7.9O 2.39 5.51
r
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A-3
Attachment A-II
Ford Data
Attachment II
Vehicle
No.
1
p
3
4
5
6
7
8
9
10
11
12
13
lU
15
16
17
18
19
PO
21
Engine
CID/L
2.3
'2.3
2.8
2.8
200
200
250
250
250
300
300
300
300
302
302
302
305
351
35?
'too
400
1
1.30 -
3.24
3.14
4.18
1.80
1.57
1.11
0.70
0.82
2.76
2.91
5.25
2.21
3.oi»
3.95
2.37
3.31
2.44
1.57
2.66
2.21
2
iJlO
3.79
3.35
1.51*
3.90
1.89
1.06
1.99
0.90
2.91
2.76 '
1.92
2.23
2.83
3.66
2.U5
2.61
2.21
1.15
2.50
2.50
3.99 4.02
2.93 3.12 3.38 2.79
2.U5
2.30
1.06
P. 21
2. 45
2.35 2.43
2.43 2.35 3.19 3.01
7-35 2.4.1
1.95
1.99 2.94 2.51 2.95
2.49
2.25 2.56
2.00
2.19
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Table 1 Average Evaporative Emissions and Exhaust Emissions
Attachment A-lll
Toyota Data
^"~"~-----^Model
I tern ~~-~~-^_^
Evaporative
Emission
(g/mile)
Exhaust
Emission
(g/mile)
Diurnal
Hot Soak
Total
HC
CO
NOx
Number of Test
Engine
Displacement
(cu.in)
Charcoal volume (cc)
Purge Control
i
Purge to
Emission Control
System
Corolla
(49 States)
3.2
1.2
4.4
0.94
7.8
Corolla
(49 States)
Corolla
(California)
1.8 j 1.8
1.0
2.8
1.0
2.8
0.77 0.28
12.4
1.3 i 1.3
i
5 11
3K-C j 2T-C
71.2
1300
Throttle
Opening
96.9
Throttle Opening
&
Coolant Temp. '
4.8
1.1
12
\
4
^
Corona
(49 States)
2.3
0.9
3.2
0.54
12.6
1.6
3
20R
133.6
<
Vehicle Speed ]VehiclJ sPee*
1
jCoolant Temp.
Carburetor J
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A-5
Attachment A-IV
Volvo Data
Vehcile
1
2
3
4
5
Test Site Control System
Volvo (1)
(2)
(3)
Volvo (1)
(3)
(2) (3)
Volvo (1)
(3)
Volvo (1)
(3)
ATL (Denver) (1)
(3)
(4)
Total Emissions, g
2.22
1.75
0.93
4.84
1.50
0.94
5.90
1.38
1.47
0.82
2.95
9.53
1.17
(1) 1977 production
(2) Increased purge rate
(3) Decreased fuel tank pressure setting
(4) 1.0 liter canister in place of standard
0.6 liter canister
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A-6
Attachment A-V
British Leyland Data
Vehicle Type
A
A
B
C
D
E
Control System
(D
(D
(D
(D
(2)
(D
(D
(D
(D
(D,(5)
(D
Diurnal, g
0.7
0.8
0.8
0.1
3.0<3>
1.3
2.7
Hot Soak, g
1.0
0.8
1.58
1.93
1.18
2.9
3.8
23.3(4)
18.5
10.1
2.05
Total, g
1.7
1.6
3.7
3.9
26.3
19.8
12.8
(1) Production System
(2) Modified 1977 California System
(3) Hydrocarbons escaping from canister
(4) Line from carburetor to canister was wet
at end of hot soak
(5) High mileage vehicle
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