P.1 

OAR Box 1856 

Prepped by Keeia Richards 

Document Number: 

64) ll-A-01 

Docket Number: 

A-87-11 

Printed 11/24/2008 12:41:50 PM Sheet 64 of 82 
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A-£"? - W -

 i'^"*/ 

February 1980 

Recommendation on Feasibility 

for Onboard Refueling Loss Control 

NOTICE 

Technical Reports do not necessarily represent final EPA decisions 

or positions. They are intended to present technical analysis of 

issues using data which are currently available. The purpose in 

the release of such reports is to facilitate the exchange of 

technical information and to inform the public of technical developments which may form the basis for a final EPA decision, position 

or regulatory action. 

Standards Development and Support Branch 

Emission Control Technology Division 

Office of Mobile Source Air Pollution Control 

Office of Air, Noise and Radiation 

U.S. Environmental Protection Agency 
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I. Introduction 

Gasoline refueling losses estimated to be in the range of 4-5 

g/gallon, can be controlled by use of control equipment at the 

service station (Stage II control) or by use of control equipment 

in the vehicle (onboard control). As required by the 1977 amendments to the Clean Air Act, the Emission Control Technology Division (ECTD) of EPA has reviewed and analyzed available data on the 

feasibility and desirability of onboard refueling loss control 

which will be discussed in this report. 

II. Summary of Conclusions and Recommendations 

Several hardware demonstrations and paper studies, Ref. 1, 2, 

have been conducted to determine the technical feasibility and cost 

effectiveness on onboard refueling loss control. Much of the 

current information is from the American Petroleum Institute (API) 

onboard demonstration program, Ref. 3. Other current information 

was obtained from motor vehicle manufacturers in response to a June 

27, 1978 Federal Register (43FR 27892) request for relevant information. These demonstrations and analyses deal with the state-ofthe-art emission control technology. 

Analysis of this information supports the following conclusions : 

1. Onboard refueling loss control is feasible for lightduty vehicles. 

2. The most probable control system uses hydrocarbon adsorption on charcoal (the same strategy that is used for evaporative 

emission control). 

3. Control effectiveness can be as high at 97%, but this 

depends especially upon the vehicle fillpipe/service station nozzle 

interface and upon control technology design. 

4. An analysis of data from three fillpipe/nozzle concepts 

(fillpipe seals, nozzle seals, and combination fillpipe/nozzle 

seals) shows that the effectiveness of all three concepts is 

approximately equal. Durability effects have not been extensively 

evaluated, especially for the nozzle seal concept. 

5. A vapor/liquid pressure relief valve is required to 

protect the integrity of the vehicle fuel tank during the refueling 

process. The pressure relief valve can be designed to function on 

the fuel nozzle, or it may be incorporated as part of the fillpipe 

seal mechanism, which would be sealed-off by the fuel cap during 

vehicle operation. Durability effects have not been evaluated for 

either the fillpipe or nozzle pressure relief. ECTD recommends 

that the fillpipe/nozzle seal and pressure relief be located on the 

vehicle if onboard controls are required. 
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6. The consumer cost for light-duty vehicle refueling loss 

control systems are estimated to be $17/vehicle. The $17 estimate 

does not include costs for a seal or pressure relief. Cost for a 

seal and pressure relief, if used on the vehicle, is estimated to 

be about $2.70. The cost of a seal on the nozzle should be the 

same as the cost for a Stage II nozzle. Except for the as yet 

undefined durability of the interface seal no maintenance costs are 

expected. 

7. The feasibility of controlling refueling loss emissions 

from gasoline fueled trucks and diesel fueled vehicles has not been 

evaluated to date. Technical feasibility and cost effectiveness of 

controlling these sources should be determined. 

8. Minor increases in CO exhaust emissions can probably be 

controlled by minor changes to either the refueling loss control 

system or to the exhaust emission control system. The ability to 

certify a vehicle to a 3.4 g/mi CO standard to 50,000 miles should 

not be seriously impaired. 

9. The use of a bladder in the fuel tank appears to be a 

viable alternative control strategy, but some problems exist and 

technical feasibility is yet to be demonstrated. 

10. Considering the lead time needed for regulation development and review within EPA and the lead time required by the 

industry for development and application of technology, implementation of onboard controls cannot occur before 1984. 

ECTD recommends that the choice between onboard control and 

Stage II control of refueling loss emissions be based upon air 

quality considerations and the relative cost effectiveness of the 

two strategies for the same overall level of control. 

It is recommended that methods of reducing the cost of onboard 

refueling control systems be examined by considering tradeoffs 

between control system capacity and cost. It may be possible to 

sacrifice some capacity that is only required under infrequent 

conditions and achieve proportionately more significant cost 

savings. 

The feasibility and desirability of control of refueling 

losses from light and heavy-duty gasoline fueled trucks and from 

diesel fueled vehicles should be considered. EPA should support 

the development of the bladder tank alternative for refueling loss 

control strategy. If regulations are to be developed for onboard 

refueling loss control, a certification test procedure must be 

developed. 
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III. Review of Available Information 

The data and information summarized in this section are based 

on material submitted to EPA by the American Petroleum Institute 

and information received in response to a request for information 

(43FR 27892) published on June 27, 1978. The API material, Ref. 3, 

is the result of their most recent study to assess onboard technical feasibility and compare the cost effectiveness of onboard 

refueling controls and Stage II controls. This study was initiated 

at the urging of EPA. Respondents to the Federal Register notice 

included General Motors, Ford, and AMC. The API, GM, and Ford 

information contain data from tests with onboard control hardware. 

All respondents, with the exception of AMC, submitted information 

on the cost and the desirability of onboard control systems. 

1. API Onboard Study 

The API Onboard Control Study was structured to address 

questions regarding onboard feasibility which were posed to API in 

a December 1977 meeting with EPA. The API study consisted of three 

tasks: a vehicle concept demonstration, a fillpipe/nozzle concept 

demonstration, and a cost/benefit analysis. Exxon Research and 

Engineering Company and Mobil Research and Development Corporation were the API contractors for the vehicle concept demonstration. Atlantic Richfield Company was the API contractor for the 

fillpipe/ nozzle concept demonstration. Exxon R & E completed the 

cost/benefit analysis for API. 

The vehicle concept modification task had the following design 

objectives: 

1) Minimum 90% overall refueling vapor recovery. 

2) No significant effect on exhaust emissions. 

3) No significant effect on evaporative emissions. 

4) Design should be durable, practical, and safe. 

The fillpipe/nozzle demonstration had the following objectives : 

1) 90% overall vapor control. 

2) Compatible with existing vehicle population. 

3) Compatible with existing Stage II nozzles. 

4) Design should be durable, practical, and safe. 

Test procedure guidelines for the API work were discussed at a 

meeting with API on March 15, 1978. Important procedural guide-
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lines which resulted from that meeting are summarized as follows: 

Fuel specification: Indolene unleaded test fuel was used for 

all exhaust, evaporative, and refueling loss measurements. 

Dispensed fuel quantity: Test vehicles were refueled to 100% 

of capacity from a condition of 10% tank capacity. 

Fuel tank temperature/Dispensed fuel temperature: The dispensed fuel temperature was selected to be representative of summer 

refueling conditions in Los Angeles during the month of August, or 

about 85°F. The fuel temperature in the tank was also selected to 

be 85°F. Thus, the refueling was isothermal.* 

Purge Cycle: For the purposes of the API study, the only 

driving cycle which was used for purging the refueling loss canister is the LA-4 cycle. 

Individually, these test procedure guidelines are considered 

to represent real world situations in a high oxidant forming 

location, e.g., Los Angeles during the month of August. Collectively, these guidelines imply that the API vehicles demonstrated 

the feasibility of onboard control systems in an approximate worst 

case condition. This reasoning is consistent with earlier EPA 

recommendations that API err on the conservative side during 

their study. For example, Exxon used the following test sequence 

to quantify the exhaust emissions interaction between the refueling 

control system and the exhaust emission control system: 

1) Load ECS (Evaporative Control System) canister to breakthrough. 

2) Condition the vehicle by driving 2 LA-4's. 

3) Soak vehicle overnight. 

4) Load RCS (Refueling Control System) canister to breakthrough. 

5) Condition the vehicle by driving 5 to 6 simulated city 

driving days (4.7 LA-4's with one hour hot soaks in between and a 

diurnal at the end of the day) to consume 90% of the fuel in the 

t ank. 

*This represents a conservative situation as survey data, Ref. 4, 

show that nationwide dispensed fuel temperatures are typically 

lower than tank fuel temperatures, thereby representing a vapor 

shrinkage situation during the refueling process. 
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6) Drain the fuel tank. 

7) Block RCS canister line. 

8) Fill tank to 40%, unblock RSC canister lines. 

9) Conduct diurnal evaporative test in SHED. 

10) Drain tank to 10%. 

11) Bring fuel tank liquid and vapor to equilibrium at 85°F 

(shake the vehicle to accelerate the equilibrium process). 

12) Refuel the vehicle to 100% in SHED with 85'F fuel. 

13) FTP 

14) Hot soak evaporative test in SHED. 

Obviously, these test procedures do not lend themselves to a 

routine laboratory certification test procedure. They do, however, 

permit an approximation of how an onboard control system would 

function in a severe "real-world" situation. 

A review of the three API contractor's activities is presented 

below. 

Exxon 

Exxon assumed the responsibilty for modifying four test 

vehicles. Their vehicles included the following: 

1978 Chevrolet Caprice 

1978 Ford Pinto 

1978 Plymouth Volare* 

1978 Chevrolet Chevette 

All vehicles were designed to comply with 1978 California 

exhaust and evaporative emission standards (.41 HC, 9.0 CO, 

1.5 NOx, 6.0 Evap). 

* Vehicle subsequently dropped from test program because of high 

baseline NOx levels. 
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The Caprice is a conventional oxidation catalyst vehicle, 

while the Pinto is a three-way catalyst vehicle with feedback 

carburetor control. Vehicle descriptions and complete refueling 

loss control system descriptions are presented in Table A-l and 

Figure A-l of the Appendix. The refueling loss canisters in the 

Caprice, Pinto and Chevette are described as follows: 

RCS 

Vehicle Carbon Volume Carbon Mass Carbon Type* Location 

Caprice 

Pinto 

Chevette 

5.0£ 

3.0£ 

3.0P_ 

1800 g 

1100 g 

1100 g 

BLP-F3 

BLP-F3 

BLP-F3 

Underhood 

Underhood 

Trunk 

* Same carbon currently used for controlling evaporative emissions, 

The Exxon exhaust and evporative emission test results which 

compare baseline and modified versions of the Caprice, Pinto and 

Chevette are summarized in Tables 1, 2 and 3. Engine-out data are 

summarized in Tables 4 and 5. Refueling loss effectiveness test 

results are summarized in Table 6. All Exxon refueling emission 

tests assumed a no-leak seal at the fillpipe/nozzle interface. In 

laboratory practice this was achieved with leak free connections 

from the fuel nozzle to the fillpipe. 

Benzene emissions from the Caprice and Pinto were measured 

during several of the refueling loss SHED tests. These results are 

summarized in Table 7. The Exxon data indicate that benzene 

control is directly proportional to refueling loss control effectiveness, although current benzene levels in the SHED are at the 

detectable limit of the instrumentation. 

Table 8 presents Exxon's manufacturer cost estimates for 

onboard control systems for the 1978 Caprice and Pinto. These 

estimates do not include the costs for fillpipe sealing devices and 

pressure reliefs. This hardware represents an additional cost 

of approximately $1.50 (manufacturer's cost) per vehicle. Exxon's 

cost estimates assume an estimated $.50 credit for downsizing the 

ECS canister, which in the two canister system, controls only 

carburetor losses. Exxon estimates the incremental cost of twocanister refueling control systems to range from $8.25 to $10.53. 

This estimate includes the above mentioned $.50 credit but does not 

include the $1.50 cost for the fillpipe seal and pressure relief. 

The corresponding cost range for single canister refueling control 

systems is $6.75 to $9.00. For light-duty trucks, Exxon estimates 

a cost range of $12 (large single canister) to $20 (two 

separate refueling loss canisters or multistage purge systems). 
Table 1 

FTP Exhaust and Evaporative Emissions - Caprice 

Exhaust (g/mi) Evap. (g) 

HC CO NOx Diurnal Hot Soak Total 

Baseline Configuration 

Modified Configuration 

n=4 

Ave. 

S.D. 

n=4 

Ave. 

S.D. 

0.345 

0.033 

0.338 

0.010 

6.48 

0.56 

7.10 

0.59 

0.95 

0.06 

0.86 

0.05 

n=3 

n=3 

0 . 8 

0 . 4 

1.1 

0 . 3 

n=4 

Ave. 

S.D. 

n=4 

Ave. 

S.D. 

0.187 

0.021 

0.217 

0.006 

1.70 

0.10 

1.83 

0.12 

0.77 

0.01 

0.79 

0.07 

n=3 

n=3 

1.0 

0 . 2 

0 . 9 

0 . 3 

2.1 2.9 

0.4 0.8 

2.1 3.1 

0.2 0.4 

Percent Change -2 +10 -10 +7 

Table 2 

FTP Exhaust and Evaporative Emissions - Pinto 

Exhaust (g/miJ Evap. (gT 

HC CO NOx Diurnal Hot Soak Total 

Baseline Configuration 

Modified Configuration 

Percent Change +16 +8 +3 -6 

2.5 

0.3 

2.4 

0.5 

3.5 

0.4 

3.3 

0.7 

I 

-J 

I 

TJ 

CO 
Table 3 

FTP Exhaust and Evaporative Emissions - Chevette 

Exhaust g/mi) Evap. (g) 

HC CO NOx Diurnal Hot Soak Total 

Baseline Configuration 

Modified Configuration 

n=3 

Ave. 

S.D. 

n=3 

Ave. 

S.D. 

0.27 

0.02 

0.26 

0.05 

3.7 

0.32 

3.6 

0.28 

1.09 

0.04 

1.13 

— 

n = 4 

0 . 8 

0.36 

0 . 3 

0.08 

2 . 6 

0.79 

1.2 

0.15 

3 . 4 

1.03 

1.5 

0.15 

I 

OO 

I 

Percent Change -4 - 3 +4 -56 

*FTP + 3 Hot Start LA-4s 

o 
Table 4 

Engine-Out Emissions - Caprice 

Baseline Configuration 

Modified Configuration 

n=5 

Ave. 

S.D. 

n=5 

Ave. 

S.D. 

1.28 

0.05 

1.29 

0.09 

26.42 

0.72 

32.04 

2.4 

1.17 

0.04 

1.17 

0.04 

Percent Change +1 + 21 

*FTP + 3 Hot Start LA-4s 

Table 5 

Engine-Out Emissions - Pinto 

FTP (g/mi) 

HC CO NOx 

City Driving Day* (g) 

HC CO NOx 

41.86 

2.00 

42.32 

1.90 

733.86 

39.27 

853.52 

61.51 

38.68 

1.17 

41.34 

3.17 

+1 + 16 + 7 

i 

vO 

I 

FTP (g/mi) 

HC CO NOx 

Baseline Configuration 

Modified Configuration 

n=4 

Ave. 

S.D. 

n=4 

Ave. 

S.D. 

1.83 

0.06 

1.77 

0.09 

52.7 

1.2 

60.1 

0.8 

1.25 

0.08 

1.12 

0.04 

Percent Change -3 + 14 -10 
Table 6 

Refueling Loss Measurements 

Potential HC (g) SHED HC (g) Percent Control Effectiveness 

Caprice 

Ave. 

93.4 

91.0 

89.3 

91.2 

0.4 

0.4 

0.3 

0.4 99 

Pint o 

Ave, 

51.0 

59. 3 

53.1 

54.5 

1.0 

1.3 

1.1 

1.1 

o 

i 

98 

Chevette 

Ave, 

62.5 

65.5 

60.1 

64.6 

63.2 

0.5 

1.5 

1.1 

1.6 

1.2 98 

TJ 

tV3 
Table 7 

Benzene Emissions 

Potential Benzene Emissions*SHED Measurements (ppm)Measure d Loss*SHED Measurements (ppm) 

Caprice 

Pinto 

3.0 

2.7 

*A11 refueling at 85°F, RVP 9 lbs., Benzene content 0.7%. 

<0.05 

<0.05 
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1 

$11 

$0 

50 

.03 

50 

$3 

2 

0 

1 

03 

00 

50 

72 

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Table 8 

COST ESTIMATES FOR ONBOARD SYSTEMS 

Caprice Pinto 

(2) 

Charcoal^' $4.96 

(3) 

Canister and Valves 2.50 

. . . (4) 

Tank Modifications 0.50 

Hoses and Tubing 1.57 

Assembling and Installing 

@ $20.00/hr. 1.50 1.50 

$8.75 

Credit for Downsized , . $0.50 $0.50 

Evaporative Control System $10.53 $8.25 

(1) Estimates are made for manufacturer's large volume production. 

(2) 1800 g for the Caprice canister, 1100 g for the Pinto canister 

at $1.25/lbm (Calgon BPL-F3 carbon). 

(3) Plastic container and valves. 

(4) Larger size float/roll-over valve. 

(5) 3/4" vapor line from fuel tank to canister, 3/8" purge line. 

EPDM tubing for vacuum control lines. 

(6) Additional 4.5 minutes labor at $20/hour. 

(7) Reduced size evaporative control canister. 
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Exxon estimates the average cost for onboard control systems 

to be $9/vehicle. This is based on the following assumptions: 

1) Onboard systems are designed to control refueling emissions from light duty vehicles with ah average fuel tank size of 17 

gallons refueled to 100% capacity from a condition of 10% tank 

capacity. The onboard systems are designed to control hydrocarbon 

emissions at a level of 6 g/gal. 

2) 70% of light-duty vehicles and single tank light-duty 

trucks are assumed to use single canister (evap + refueling) 

systems. 

3) 30% of light-duty vehicles and single tank light-duty 

trucks are assumed to use two canister systems. 

4) Light duty trucks with dual or large fuel tanks constitute approximately 10% of the light-duty vehicle and light-duty 

truck population. 

In summary, Exxon finds that onboard refueling controls for 

light-duty vehicles are a technically feasible, practical, and cost 

effective alternative to Stage II vapor recovery. They are of the 

opinion that the same may also be said for light-duty trucks. 

Mobil 

Mobil R&D has modified a 1978 Pontiac Sunbird for control of 

refueling losses. This vehicle has a three-way catalyst with a 

feedback carburetor control system, and is certified for complaince 

with California exhaust and evaporative emission standards. 

This modified vehicle uses a single canister which contains 1550 

grams of Calgon BLP-F3 carbon. The complete vehicle and refueling 

loss control system descriptions are presented in the Appendix. 

Table 9 presents comparisons of exhaust and evaporative emissions 

from the Sunbird for the baseline and modified configurations; a 

summary of the refueling emission data is presented in Table 10. 

Similar to Exxon's findings, Mobil states that their test 

results have demonstrated that onboard controls are a feasible and 

desirable method of controlling refueling losses from light-duty 

vehicles and light-duty trucks. 

Atlantic Richfield Company 

One of the requirements for the operation of an effective 

refueling loss control system is a no-leak seal at the fillpipe 

nozzle interface. Atlantic Richfield (ARCO) has designed and 

tested three types of sealing systems. They included: 

1) Modification of the vehicle fillpipe to achieve a seal 

when used with conventional lead-free nozzles. 
Table 9 

FTP Exhaust and Evaporative Emission Comparisons — Sunbird 

Exhaust (g/mi) 

HC CO NOx Diurnal 

Evap. (g) 

Hot Soak Total 

Baseline Configuration 

Modified Configuration 

n=9 

Ave. 

S.D. 

n=6 

Ave. 

S.D. 

0.39 

0.03 

0.40 

0.03 

6.41 

0.91 

6.35 

0.74 

0.98 

0.07 

0.99 

0.03 

n=2 

n=4 

0.87 

030 

0.72 

0.23 

1.12 

0.13 

1.27 

0.37 

2.00* 

0.34 

2.11 

0.56 

Percent Change + 3 -1 + 1 +6 

* Includes five tests at low mileage where individual diurnal and hot soak results are not available. 

•pi 

Table 10 

Refueling Loss Measurements — Sunbird 

Fuel Dispensed (gal) HC Collected in Canister (g)* 

Refueling Emissions 

SHED Measurements (g/gal) 

Control 

Efficiency (%) 

16.4 

15.3 

16.9 

17.1 

85 

73 

113 

109 

0.18 

0.02 

0.44 

0.36 

* Canister purged from a nominal working capacity load of 210 g. 

Fuel of nominal 9 lbs. RVP. 

8 gpm refueling rate, using modified Stage II nozzle. 

97 

99 

94 

95 
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2) Modifications to both the fillpipe and lead-free nozzle. 

3) Modification of a Stage II vapor recovery nozzle. 

A description of each type of seal and a summary of the 

durability data collected with each system are presented below: 

Fillpipe seals: Two types of fillpipe seals have been examined. They are a rotary grease seal (similar to grease seals 

used on rotating machinery shafts), and a doughnut shaped seal. 

The material types for these two seals are a compounded nitrile and 

thermosetting urethane, respectively. More complete descriptions 

of these seals, including durability data, are found in Figure 

A-5 and Tables A-2 and A-3 of the Appendix. Appproximately thirty 

days of durability tests with both types of seals have demonstrated 

that the rotary seal is more effective, basically due to the 

absence of expansion problems when exposed to gasoline liquid and 

vapor atmospheres. The seal effectiveness of the prototype fillpipe and nozzle hardware are determined by a bench test apparatus 

which pressurizes a particular system and measures the resulting 

leak rates. Seal effectiveness calculations are determined by 

dividing the leak rate by a nominal fueling rate (assumed to be 7.5 

gallons/min.). Durability tests conducted with the rotary seal 

have demonstrated that the rotary seal is effective after 700-1000 

nozzle insertions, which correspond to the number of fuel fills 

expected during the life of the vehicle. 

Combination fillpipe/nozzle seals: These systems consist of 

connecting parts on both the fillpipe and nozzle. Figure A-6 is an 

example of a prototype design evaluated by ARCO. Durability test 

results with these systems are similar to results obtained with the 

rotary seal. 

Nozzle Modification: Working prototypes of vapor recovery 

nozzles, modified for refueling loss control, have been developed 

by OPW and Emco Wheaton and evaluated by ARCO for effectiveness and 

durability. These nozzles are designed to seal on standardized 

fillpipes. The modified vapor recovery nozzles incorporate a 

pressure relief valve, which is located at the vapor return exit or 

cast into the nozzle body and designed to open at approximately 

14-17 in. water pressure*, thereby permitting the nozzle to refuel 

onboard control vehicles and in-use vehicles. Nozzle durability 

data are very limited but one nozzle has been inserted and latched 

7500 times, representatitve of one year of service at a high volume 

station, and showed a seal effectiveness of greater than 99%. 

ARCO concludes that the preferred seal techniques are either 

the fillpipe seal method or the combination fillpipe/nozzle seal. 

* Refueling loss control systems designed by Exxon and Mobil are 

designed to operate at fill pressures of less than 4 in. of water 

pressure. 
P.18 

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2. Vehicle Manufacturer Information 

General Motors 

General Motors has several reservations concerning the applicability of onboard controls, citing such things as: the uncertainty of the effectiveness of fillpipe/nozzle seals, potential 

cost increases associated with exhaust emission control systems 

which must be designed to control increased CO emissions, negative 

fuel penalties which are the result of this increased emission 

control, and the long lead time which is required to obtain a 

substantial reduction in atmospheric hydrocarbon and benzene 

loading. GM has stated that refueling losses can be controlled on 

the vehicle (feasibility for trucks has not been demonstrated) or 

at the service station. GM's disagreements with controlling 

refueling emissions with onboard controls are primarily based on 

the issue of cost/effectiveness. 

More recently, (Ref. 13 & 14), GM has expressed concern about 

possible inadequacies in the design of the API demonstration 

vehicles. Specifically, GM states that a large diameter refueling 

vent and a small restricted vent are necessary for protection from 

overfilling the fuel tank and preventing excessive hydrocarbon 

loading of the storage canister during high temperature vehicle 

operation. 

GM's March, 1978 submission to EPA presents a summary of their 

work on the control of diurnal evaporative emissions and refueling 

losses using fuel tank bladders. 

It is EPA's opinion that the theoretical control effectiveness 

of evaporative and refueling loss emissions using bladder tank 

technology is high and that problems related to vapor storage, 

pressure relief valves, and bladder materials can be solved. It 

is recommended that bladder tank feasibility be researched by 

funding a bladder tank hardware demonstration contract. 

The March, 1978 submission presents calculations showing that 

the additional weight of the components of an onboard control 

system will cancel out any potential energy saving which results 

from the combustion of the refueling vapors. ECTD agrees with 

this analysis. 

The June, 1978 submission is basically a cost effectiveness 

analysis comparing onboard controls with Stage II controls (balance 

displacement and vacuum assist systems). GM estimates that onboard 

control systems, effective with the 1982 model year, will range 

from $16 to $24. These figures are about $5 to $9 higher than the 

March, 1978 estimates due to higher estimates for larger canisters 

and a new vapor/liquid separator. GM assumes that the seal at the 

fillpipe/nozzle interface will be obtained using modified vapor 
P.19 

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covery. Rather, GM emphasizes certain technical concerns which 

they say are not fully addressed by the API study. According to 

GM, these include API's unsubstantiated support for the onboard 

fillpipe seal and pressure relief (lack of adequate durability 

results), an unknown CO penalty for light-duty vehicles (no sensitivity data relating CO to test procedure differences), and unproven feasibility for trucks. 

GM is of the opinion that accelerated laboratory durability 

tests are not sufficient to prove that proposed elastomer type 

seals will be effective in the extreme usage and environmental 

conditions of the real world, particularly when considering a ten 

year average lifetime for a light-duty vehicle. 

Ford 

Ford has submitted test results from four 1978 model year 

vehicles (three non-feedback systems and one feedback control 

system) modified for refueling loss control. These vehicles are 

described in detail in Table A-4 in the Appendix and in their 

submission to EPA, Ref. 7. The purge control systems for these 

vehicles are shown in Figures A-7 and A-8 in the Appendix. 

Ford estimates the cost to the consumer of onboard controls to 

range from $15-$20. They note that the $15-$20 estimate does not 

include additional expense for such items as: packaging costs, 

incremental labor costs, or the costs for additional exhaust 

emission control, such as feedback control over a wider air/fuel 

ratio range. 

Recent Ford material, Ref. 12, suggest that the cost of 

onboard systems may range from $30 to $253. The $30 estimate 

includes costs over the original $15-20 estimate, including costs 

for such items as vehicle modifications to package onboard systems, 

incremental assembly, and material substitution. The $253 estimate 

includes the cost for a feedback fuel system and electronic controls for vehicles which are not planned to be equipped with these 

control devices. 

On the basis of their in-house test results, Ford has concluded that onboard controls are not technically feasible for lightduty vehicles. 

American Motors 

AMC has submitted a letter to EPA, Ref. 9, which states their 

concerns with the possible use of onboard controls. They state 

that packaging concerns, reduced quantities of purge air from 

downsized engines, and compliance with stringent evaporative 

emission standards are unresolved technical issues which have not 

been addressed by the API work to date. 
P.20 

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AMC does not find that API has demonstrated light-duty vehicle 

technical feasibility. 

IV. Analysis of Available Information 

1. API Work 

Exxon 

Exxon R&E appears to have done a credible job in characterizing the components of a hydrocarbon adsorption system. An 

examination of the results from baseline tests and tests with the 

modified Pinto (3-way + feedback carburetor system) show small but 

finite increases in engine-out (14%) and tailpipe (8%) CO emissions. HC, CO, and NOx emissions are still well below statuatory 

emission levels for low mileage vehicles. Engine-out CO emissions 

from the Caprice are approximately 20% higher than baseline test 

results; tailpipe CO emissions are approximately 10% higher than 

the baseline results. No increase in tailpipe CO was observed 

during tests with the Chevette. Exxon suggests that differences in 

CO emissions for the Caprice and the Pinto can be further reduced 

by minor modifications to the refueling loss control system or the 

exhaust emission control system, although this has not been demonstrated. 

Figure A-2 shows canister purge as a function of time. 

Although the data are bench test results, the results are also 

representative of actual control system purge data. It is significant to note that the refueling loss canister is essentially purged 

to its working capacity after three LA-4 driving days. This 

implies that the refueling control/exhaust emission interaction is 

likely to be less in a typical driving day than Exxon has measured 

using conservative test methods, which required running a cold 

start FTP immediately after a 90% refueling. 

ECTD expects that refueling loss control systems will result 

in slightly higher CO feedgas levels. Exxon estimates that the 

average increases in CO feedgas between refuelings will be approximately 5% for non-feedback control systems and less than 3% for 

feedback control systems. ECTD has no other data concerning either 

the magnitude of the average CO feedgas penalty or the resulting 

effect on catalyst durability. It is ECTD's opinion that the Exxon 

estimates are reasonable and that these additional CO penalties 

will make it more difficult for vehicle manufacturer's to certify 

some engine/families to the 3.4 g/mi CO standard. The higher CO 

levels somewhat reduce the margin available to allow for exhaust 

system deterioration over 50,000 miles. 

ECTD finds that light-duty vehicles equipped with onboard 

systems are capable of meeting a 2 gram evaporative emission 

standard. 
P.21 

-19-

An analysis of the control effectiveness of benzene emissions 

during refueling, Table 6, indicates that charcoal canisters can 

control in excess of 99% of the uncontrolled benzene emissions. 

Exxon conducted additional tests with the Caprice and Pinto using 

indolene test fuel with a high benzene content (4.2%). The results 

from these five tests suggest that benzene emissions are controlled 

in excess of 99% during refueling. 

Packaging refueling loss control systems is a difficult 

problem, but definitely not an insurmontable one. The refueling 

loss canister is located behind the rear seat and above the rear 

axle in the Caprice, and in the engine compartment of the Pinto. 

It is Exxon's opinion, and ECTD agrees, that' it is possible for 

manufacturers to locate a refueling loss canister on downsized 

vehicles without major engine compartment or sheetmetal modifications . 

The feasibility of refueling loss controls for light-duty 

trucks has not been evaluated by Exxon, but they are of the opinion 

that refueling loss control is feasible for light-duty trucks by 

using larger control systems and more sophisticated purging controls (refueling loss control canisters for each tank and/or two 

stage purging systems). It is ECTD's opinion that the control of 

refueling losses from light-duty trucks needs to be demonstrated, 

especially the ability to comply with a 2 g evap standard, before 

onboard controls are judged to be effective for these vehicles at 

the costs Exxon has estimated. 

Table 8 shows Exxon's detailed manufacturer's cost estimates 

for refueling control systems which have two canisters. ECTD finds 

these cost estimates to be reasonable for onboard systems designed 

to control 100% of refueling emissions from 90% fill conditions. 

Exxon estimates the average manufacturer's cost for the light-duty 

truck and light-duty vehicle population to be about $9. That 

number is derived as follows: 

One-cansiter vehicles* 

Two-canister vehicles* 

6,000 to 8,500. lbs. trucks** 

Weighted average $9.00 

As sume 

Average 

$7.88 

$9.3 8 

$16.00 

d 

Cost Pc 

% of 

>pulation 

70 

20 

10 

* Includes light-duty vehicles and light-duty trucks under 6000 

GVW - average fuel tank size = 17 gal. 

** Average fuel tank size = 35 gal. 

The charcoal cost per gallon of tank volume is assumed to be about 

$0.20. 
P.22^ 

-20-

Th e $9 incremental manufacturer cost may be translated to a 

consumer cost estimate of $16.20 by multiplying the manufacturer's 

cost estimate by a factor of 1.8 (Ref. 10, EPA Report "Cost Estimations for Emission Control Related Components/Systems and Cost 

Methodology Description" by Rath and Strong, March 1978). The 1.8 

factor is in general agreement with previous EPA studies, such as 

the EPA Report, Ref. 11, "Investigation and Assessment of LightDuty Vehicle Evaporative Emission Sources and Control," June 1976, 

which used a manufacturer to consumer cost factor of 2.0. The 

$16.20 estimate is in good agreement with consumer cost estimates 

submitted by GM ($16-$24) and Ford ($15-$20). It is possible to 

further reduce the cost of an onboard system by trading off some 

degree of refueling loss control effectiveness. 

Exxon has designed refueling loss control systems based on 

conservative criteria, and thus a different set of design criteria 

will afford reductions in the cost of onboard control systems. 

Texaco has submitted data (Figure A-ll) Ref. 12, which relates the 

number of light-duty vehicle refuelings and the percent of tank 

fill. A reasonable design criterion is to size the refueling 

canisters to control 90% of nationwide refueling emissions. 

Calculations (Figure A-12) show that 90% control can be achieved by 

designing systems to control 100% of refueling emissions from fills 

to 63% of fuel tank volume. If onboard control systems are designed to control emissions from refueling to 63% of tank capacity 

rather than 90% of tank capacity, the Exxon estimate of $9 per 

vehicle can be reduced by $1.60 as the result of reduced charcoal 

quantity. This cost reduction is proportional to the reduction in 

carbon bed volume. The net effect of this design change is a cost 

reduction to the consumer of approximately $2.88. Changes in 

design specifications such as the 90% fill requirement may afford 

additional cost reductions for other control system components as 

well as a general reduction in the problem of packaging onboard 

control systems. 

ECTD estimates the consumer cost of light-duty vehicle onboard 

control systems designed for maximum control effectiveness to be 

about $17. This estimate does not include an estimate for the cost 

of the fillpipe seal or pressure relief valve. The $17 estimate is 

based on Exxon estimates, which when translated to consumer costs, 

are in agreement with consumer cost estimates provided by GM and 

Ford. 

Exxon estimates the manufacturer's cost for a fillpipe seal 

and onboard pressure relief valve to be approximately $1.50. ECTD 

estimates the consumer cost of an onboard fillpipe seal and pressure relief to be $2.70. 

Mobil 

Comparisons of baseline and modified vehicle test results 

indicate that Mobil R&D is able to add refueling controls to the 
P.23 

-21-

1978 Pontiac Sunbird (3-way + feedback carburetor system) without 

adversely affecting exhaust or evaporative emissions. No changes 

in engine-out or tailpipe CO emissions are observed. Evaporative 

emissions are also unchanged, with both baseline and modified 

vehicle test results near the 2 g evaportive emission level. 

It must be emphasized, however, that Mobil and Exxon use 

different test procedures for measuring the refueling control/ 

exhaust emission interaction. Mobil's test procedure consists of 

the following sequence of events: 

1) Load canister to approximately one-half of working 

capacity. 

2) Condition vehicle by driving two simulated city driving 

days (4.7 LA-4's with one hour hot soaks in between and a diurnal 

at the end of the day). 

3) Drain fuel tank to 10% of volume. 

4) Refuel to 90% of volume in SHED. 

5) Conduct hot start emission test. 

6) Soak vehicle for 11 hrs. 

7) Conduct diurnal evaporative test in SHED. 

8) FTP 

9) Hot soak evaporative test in SHED. 

Steps 1, 2, and 5 are the important differences between the 

test procedures used by Exxon and Mobil. Mobil starts their test 

sequence with a canister loaded to one-half of working capacity, 

versus a saturated condition for the Exxon procedure. Mobil purges 

the refueling loss canister with two LA-4 driving days, versus the 

Exxon method of purging by running a series of LA-4 driving days 

until the fuel tank reaches 10% of capacity. Mobil runs a hot 

start emission test prior to the FTP; no such additional conditioning is used in the Exxon test sequence. It is ECTD's opinion that 

the the Mobil test sequence, particularly the addition of a hot 

start exhaust emission test, will result in a less severe refueling 

control/exhaust emission interaction. This is due to the smaller 

quantity of hydrocarbon which is purged during the cold start FTP 

when using the Mobil test sequence. The actual emission sensitivity to various test procedure arrangements has not yet been 

determined. 

Atlantic Richfield Company 

ARCO states that the fillpipe modification approach and the 
-22-

combination fillpipe/nozzle seal concept are the preferred techniques for achieving a no-leak seal. This recommendation is not 

supported from an analysis of leak rate and durability data because 

the test results show that seal effectiveness among all three 

concepts are equal. Cost estimates for the three designs have not 

been submitted. ARCO is continuing to collect field durability 

data on their prototypes, but the lack of a more extensive durability demonstration under simulated conditions of real world usage 

makes it questionable to assume that their seals will function as 

well in the field as they have in the laboratory. 

In particular, ARCO has not adequately addressed the issue of 

onboard pressure relief valves versus liquid pressure relief valves 

located on the fill nozzle. Pressure relief valves are necessary 

to prevent over-pressurization of the fuel tank in the event of a 

failure of the automatic shutoff on the fill nozzle. For the 

purpose of fuel tank integrity in the event of a vehicle crash, 

NHTSA recommends that the pressure relief not be located on the 

fuel tank. However, a relief valve might be incorporated safely 

with a fillpipe seal mechanism, which would be sealed-off by the 

fuel cap during vehicle operation. 

The achievement of a safe and durable seal at the nozzle 

fillpipe interface is critical to the performance of an onboard 

refueling loss control system. ARCO has demonstrated that the 

effectiveness of fillpipe seals, combination seals and nozzle 

seals are equal; but the design, location, and durability of the 

pressure relief valve have not been adequately addressed. 

Conceptually, a pressure relief may be designed to function 

properly when located on the vehicle or on the nozzle. However, if 

refueling losses are controlled on the vehicle, it is recommended 

that the fillpipe/nozzle seal and pressure relief valve also be 

located on the vehicle. Locating all parts of an onboard system on 

the vehicle will prevent the potentially serious problem of refueling a controlled vehicle without protection from overpressurization 

(no relief valve). Administrative and certification concerns also 

suggest that onboard controls are practical only if the seal and 

pressure relief are located .onboard. 

An alternative technique of achieving a seal at the fillpipe/ 

nozzle interface is the liquid trap or submerged fill. This seal 

concept has not been adequately investigated. Submerged fill 

offers the potential for significant advantages in terms of simplicity of operation and durability (mechanical, magnetic, or elastomer type seals are avoided). It is ECTD' s opinion that the 

submerged fill concept should be investigated. Submerged fill (and 

seal techniques investigated by ARCO) must be evaluated in the 

context of a complete refueling and evaporative emission control 

system. This includes incorporating features to provide adequate 

thermal expansion capability and rollover protection while still 

permitting normal safe refueling. 
-23-

2. Vehicle Manufacturer Information 

General Motors 

General Motors has several reservations concerning the applicability of onboard controls, citing such things as: the uncertainty of the effectiveness of fillpipe/nozzle seals, potential 

cost increases associated with exhaust emission control systems 

which must be designed to control increased CO emissions, negative 

fuel penalties which are the result of this increased emission 

control, and the long lead time which is required to obtain a 

substantial reduction in atmospheric hydrocarbon and benzene 

loading. GM has stated that refueling losses can be controlled on 

the vehicle (feasibility for trucks has not been demonstrated) or 

at the service station. GM's disagreements with controlling 

refueling emissions with onboard controls are primarily based on 

the issue of cost/effectiveness. 

More recently, (Ref. 13 & 14), GM has expressed concern about 

possible inadequacies in the design of the API demonstration 

vehicles. Specifically, GM states that a large diameter refueling 

vent and a small restricted vent are necessary for protection from 

overfilling the fuel tank and preventing excessive hydrocarbon 

loading of the storage canister during high temperature vehicle 

operation. 

GM's March, 1978 submission to EPA presents a summary of their 

work on the control of diurnal evaporative emissions and refueling 

losses using fuel tank bladders. 

It is EPA's opinion that the theoretical control effectiveness 

of evaporative and refueling loss emissions using bladder tank 

technology is high and that problems related to vapor storage, 

pressure relief valves, and bladder materials can be solved. It 

is recommended that bladder tank feasibility be researched by 

funding a bladder tank hardware demonstration contract. 

The March, 1978 submission presents calculations showing that 

the additional weight of the components of an onboard control 

system will cancel out any potential energy saving which results 

from the combustion of the refueling vapors. ECTD agrees with 

this analysis. 

The June, 1978 submission is basically a cost effectiveness 

analysis comparing onboard controls with Stage II controls (balance 

displacement and vacuum assist systems). GM estimates that onboard 

control systems, effective with the 1982 model year, will range 

from $16 to $24. These figures are about $5 to $9 higher than the 

March, 1978 estimates due to higher estimates for larger canisters 

and a new vapor/liquid separator. GM assumes that the seal at the 

fillpipe/nozzle interface will be obtained using modified vapor 
P.26 

-24-

recovery nozzles. GM does not include seal costs in its estimate. 

They assume these costs will be the same for either Stage II or 

onboard controls and hence, leave these costs out of their analysis of both options. General Motor's onboard cost estimates are 

costs to the consumer. These estimates are based on costs for 

hydrocarbon adsorption systems which control evaporative and 

refueling emissions with one canister and systems which use two 

separate canisters for containing evaporative (diurnal and hot 

soak) and refueling emissions. The GM cost estimates are consisten t with Exxon's manufacturers cost estimate s for onboard 

controls. As discussed earlier, i t is possible to design cheaper 

refueling loss control systems by not providing 100% control of 

refueling emissions under worst case conditions. If the design 

criterio n of 100% contro l for a 90% refuelin g is changed to 

100% control for a 63% refueling, it is possible to reduce the 

required working capacity of the charcoal canister, thus reducing 

the average system cost to the consumer by about $3.00. 

GM did not comment on the feasiblity of refueling loss controls for light-duty trucks and heavy-duty gasoline powered vehicles. 

Ford 

Ford emphasizes that the refueling loss/exhaust emissions 

interaction is a function of the test procedure and that the 

differences between emissions interactions measured by Exxon and 

Mobil are due to test procedure differences. This statement is 

correct, although the actual emission sensitivity to the test 

procedure is unknown. 

Ford attributes the high CO effects which they have observed 

with both conventional oxidation catalyst systems and three-way 

plus feedback carburetor systems to the presence of refueling loss 

controls. However, high CO emissions are likely the result of 

using a manifold vacuum purge control system. This system results 

in cold-start hydrocarbon loadings that are two to three times 

higher than results obtained with venturi vacuum control systems 

(Exxon system). This is the reason the Ford results are so high, 

particularly engine-out CO emissions. Ford maintains that refueling loss control systems produce peak enrichment effects equal to 

two air/fuel ratios, which is beyond the capability of their 

current feedback carburetor control system. Exxon has demonstrated, however, that venturi vacuum maintains the air/fuel ratio 

within the control limits of the feedback control system. Problems 

with the existing Ford feedback control system are likely to be the 

result of response time problems, not control range problems. 

Some of Ford's concerns with onboard refueling control systems, such as packaging, weight of onboard systems, and the design 

of vapor/liquid separators have been examined during the API study 
P.27 

-25 -

and shown not to be significant problem areas. Other concerns with 

onboard controls, including system durability, onboard feasiblity 

for light and heavy duty trucks, and high altitude feasibility, 

have not been adequately addressed in any of the information 

submitted to ECTD. It remains ECTD's judgment that these issues 

need further examination, particularly before onboard controls are 

determined to be feasible for light and heavy-duty trucks. Although onboard durability data are not available, ECTD finds that 

onboard control systems should be as durable as current evaporative 

emissions control systems, which last for the lifetime of the 

vehicle. 

Ford estimate s the consumer cost of onboard controls for 

light-duty vehicles to range from $30 to $253. EPA estimates that 

the consumer cost of onboard control systems will be about $20 

(include s $2.70 for the cost of an onboard sea l and pressur e 

relief). 

American Motors 

AMC's concerns with the use of onboard controls are addressed 

to the issues of exhaust and evaporative emissions interactions, 

feasiblity of vehicles using small engines, costs, and light-duty 

truck feasibility. With the exception of feasibility for lightduty trucks, AMC's concerns have been examined in detail by the API 

study. EPA's analysis of that data is that refueling loss controls 

are feasible for light-duty vehicles at a consumer cost of approximately $17. 

V. Conclusions 

Feasibility 

An Analysis of the available information has shown that 

onboard refueling loss controls are feasible for light-duty 

vehicles designed to meet low exhaust and evaporative emission 

standards (0.41 HC, 3.4 CO, 1.0 NOx and 2.0 Evap.). However, the 

feasibility for light-duty trucks, particularly the assurance that 

onboard control systems are compatible with a 2 gram evaporative 

emission standard, has not been established. Feasibility for 

heavy-duty gasoline vehicles has not been established. 

An analysis of information and test data presented to EPA 

regarding the control of light-duty vehicle refueling emissions 

offers the following conclusions: 

1. Onboard control systems in laboratory use situations can 

control in excess of 97% of the uncontrolled hydrocarbon refueling 

losses. 
P.28 

-26-

2. The same systems in laboratory use situations can control 

in excess of 97% of the uncontrolled benzene refueling losses. 

3. Test results from two light-duty vehicles equipped with 

three-way catalysts, feedback carburetors, and prototype refueling 

loss systems show that tailpipe CO emissions range from a 0 to 8% 

increase. 

Test results from the same vehicles show that engine-out CO 

emissions range from a 0 to 14% increase. 

4. Emission data from two conventional oxidation catalyst 

equipped light-duty vehicles show that tailpipe CO emissions 

range from a 0 to 10% increase. 

Data from one of the conventional oxidation catalyst vehicles 

show that engine-out CO emissions increase by 10 to 20%. 

5. The addition of refueling loss controls to light-duty 

vehicles does not significantly affect evaporative emission losses. 

6. Minor increases in CO exhaust emissions seen for some 

vehicles can probably be controlled by minor change to either the 

refueling loss control system or to the exhaust emission control 

system. However, the addition of refueling loss controls will 

likely make it more difficult to certify some vehicles to the 3.4 

g/mi standard at 50,000 miles. 

7. Onboard controls do not affect vehicle fuel economy. 

8. Onboard controls do not affect vehicle driveability. 

9. Refueling loss control systems for light-duty vehicles 

are estimated to add $17 to the vehicle sticker price. The $17 

estimate does not include the costs associated with the fillpipe/ 

nozzle seal or pressure relief valve. The consumer cost of a seal 

and pressure relief in the fillpipe is estimated to be about $2.70. 

The cost of a seal on the nozzle should be roughly the same as the 

cost for a Stage II nozzle. However, it is recommended that all 

components of an onboard control system be located on the vehicle. 

Lead time 

Onboard refueling loss control can be implemented for 1984 

model year light-duty vehicles, provided that potential problem 
P.29 

-27-

areas such as the design and development of effective fillpipe/ 

nozzle seals and pressure relief valves do not require additional 

hardware demonstration programs. It is anticipated that the 

fillpipe/nozzle seal and the control feasibility for light and 

heavy-duty trucks are issues which can be resolved during the NPRM 

process. 

ECTD estimates that a minimum of two years leadtime will be 

required by manufacturers for development (purge system optimization, design and verification of fillpipe seal mechanisms) and 

production tooling changes (tooling associated with fabrication and 

relocation of new evaporative control components). These estimates 

are based in part upon data provided by manufacturers relating to 

carburetor tooling changes, and in part upon data supplied by GM 

relating to retooling changes for body panel modifications. 

Additional time will be required for EPA to develop a certification 

type test procedure and issue regulations; however, the certification procedure development can overlap the production tooling lead 

time. Therefore, the projection is that an NPRM can be published 

in 1980 with final rules promulgated by 1981 with the earliest 

possible implementation date being 1984. (See lead time chart, 

Figure 1). 

Compliance Costs 

ECTD estimates that certifying light-duty vehicles for compliance with a refueling loss standard will require an additonal 

one-half person-year at the EPA-MVEL. This is based on an estimate 

of 100-150 refueling loss tests per year. Facility modifications/ 

equipment procurements will cost from $30K to $80K. 

A potentially significant impact on refueling loss compliance 

costs is Inspection/Maintenance testing of light-duty vehicles. 

EPA has not developed, and is not aware of, a valid I/M test for 

determining the performance of evaporative emission control systems. Monitoring the performance of in-use refueling loss control 

systems will be difficult and cumbersome. At this time, it may be 

assumed that the onboard compliance costs associated with an I/M 

test will be equal to the cost of Stage II enforcement. 

VI. Recommendations for Future Work 

1. ECTD recommends that additional hardware testing be 

conducted to determine the optimal fillpipe-nozzle seal. Additionally, the operation and durability of a fillpipe or nozzle pressure 

relief (including overfill protection for liquid expansion) must be 

demonstrated. The use of an onboard liquid trap seal (submerged 

fill) as an alternative to elastomer type seals should be investigated. 
Publish NPRM 

Final Rule 

P.30 

-28-

Figure 1 

Lead Time 

Quarter: 

Develop Certification 

Test Procedure 

Continued Study of 

Fillpipe/Nozzle Seal 

Concepts 

Calendar Year 

1980 1981 1982 1983 1984 

1234 1 1234 1 1234 1 1234 1 1234 1 

Decision on Seal 

Concepts 

-(Decision to publish service station nozzle 

requirements or put seal on vehicle) 

EIS, EIA, NPRM 

Preparation 

Manufacturers 

Lead Time 1984 MY 
P.31 

-29-

2. ECTD recommends that additional hardware testing be 

conducted to assess the feasibility of controlling refueling 

losses on light-duty trucks and heavy-duty gasoline powered 

trucks. 

3. ECTD recommends that the need for controlling refueling 

losses from diesel powered vehicles be investigated since these 

vehicles are predicted to represent a substantial fraction of the 

entire motor vehicle population in the 1980's. 

4. ECTD recommends that the bladder fuel tank be investigated as an alternative to carbon adsorption technology. It is 

ECTD's opinion that the theoretical control of ecvaporative and 

refueling loss emissions with bladder tanks is high and that 

technical problems can be solved. It is recommended that bladder 

tanks feasibility be researched by funding a hardware demonstration 

contract. 

5. Finally, ECTD recommends that methods of reducing the 

cost of onboard refueling control systems be examined. Such 

studies should be directed toward tradeoffs between level of 

control effectiveness and cost. It may be possible to sacrifice 

control capacity that is required under only infrequent conditions 

to achieve a proportionally more significant cost savings. 
P.32 

-30-

References 

1. "Control of Refueling Emissions," Statement by General Motors 

Corporation, June 11, 1973. 

2. "Control of Refueling Emissions with an Activated Carbon 

Canister on the Vehicle - Performance and Cost Effectiveness 

Analysis," Interim Report Project EF-14, prepared for the 

American Petroleum Institute, Washington, D.C, October 1973. 

3. "On-Board Control of Vehicle Refueling Emissions - Demonstration of Feasibility," API Publication No. 4306, October 1978. 

4. "Summary and Analysis of Data from Gasoline Temperature Survey 

Conducted at Service Stations," Radian Corporation, Austin, 

Texas. Prepared for the American Petroleum Institute, Washington, D.C, November 1976. 

5. "General Motors Commentary to the Environmental Protection 

Agency Relative to On-Board Control of Vehicle Refueling 

Emissions," March 1978. 

6. "Suppplement to General Motors Commentary to the Environmental 

Protection Agency Relative to On-Board Control of Vehicle 

Refueling Emissions," June 1978. 

7. "Ford Motor Company Response to EPA Concerning Feasibility and 

Desirability of a Vehicle On-Board Gasoline Vapor Recovery 

System." 

8. "Ford Motor Company Position Concerning Feasibility and 

Desirability of Vehicle On-board Refueling Vapor Control 

Systems," November 6, 1978. 

9. AMC letter to Paul Stolpman, August 3, 1978. 

10. "Cost Estimations for Emission Control Related Components/Systems and Cost Methodology Descriptions," Rath and Strong, 

Inc., Lexington, Massachusetts. Prepared for the Environmental Protection Agency, Ann Arbor, Michigan, March 1978. 

11. "Investigation and Assessment of Light-Duty Vehicle Evaporative Emission Sources and Control," Exxon Research and 

Engineering Company, Linden, New Jersey. Prepared for the 

Environmental Protection Agency, June 1976. 

12. Texaco statement submitted to Paul Stolpman, July 18, 1978. 
P.33 

APPENDIX 

The Appendix contains detailed descriptions and data from the 

test vehicles and fillpipe/nozzle seals which were used in the most 

recent testing and evaluation of refueling loss control systems. 

Exxon 

Table A-l presents a description of all Exxon test vehicles. 

Figure A-l is a schematic of the basic control system designed for 

the Chevrolet Caprice and the Ford Pinto. The refueling emissions 

(RCS) canister controls both refueling emissions and diurnal 

evaporative emissions; the evaporative emissions (ECS) canister 

controls carburetor hot soak losses. Exxon investigated several 

different purge mechanisms, including combinations of manifold 

vacuum and venturi vacuum, and two stage purge control valves 

controlled by fuel volume, but venturi vacuum, which is proportional to engine air flow, is the most effective purging method. 

Exxon's control system is designed to maintain the total purge air 

volume (RSC + ECS) equal to the purge air volume of the unmodified vehicle's evaporative control system. 

The air bleed control valve, shown in Figure A-l, is necessary 

because the RCS canitser is purged more efficiently (higher hydrocarbon purge per unit volume of air) than the unmodified ESC 

system, thereby resulting in richer A/F mixtures. This air bleed 

may not be necessary for other vehicles with feedback carburetor 

controls. 

Figure A-2 is a plot of the RCS canister purging as a function 

of time. These data are based on consecutive LA-4 driving days. 

As noted, the RCS system is purged at a rate of about 4 litres/ 

min., which corresponds to a total canister purge volume of about 

40 litres during an LA-4 driving cycle. 

Mobil 

Specifications for the vehicle Mobil has modified for refueling loss control are summarized as follows: 

Vehicle: 1978 California Pontiac Sunbird 

Engine Size: 151 cu. in. L-4 

Interia Weight: 3000 lbs. 

Emission Control System: 

Exhaust: 3-way catalyst with feedback carburetor, 

EGR 

Evaporative: Carbon canister 
A-2 

Fuel Tank Capacity: 18.5 gallons 

The production vehicle is modified for controlling refueling 

emissions by enlarging the existing carbon canister, (one canister 

controls refueling, diurnal, and hot soak loss), enlarging the 

vapor line between fuel tank and canister, redesigning the vapor/ 

liquid separator, and installing a purge control orifice between 

the canister and intake manifold. A schematic of the Sunbird's 

control system is shown in Figure A-3. Various flow control 

orifices were inserted in the canister purge line but best results 

are obtained with an orifice of 0.100 in. diameter. Mobil uses 

1550 grams of Calgon BPL-F3 carbon for their control system, which 

assumes a 20% safety factor. This quantity of carbon is based on a 

90% fill of the 18.5 gallon tank, and assumes a hydrocarbon loading 

of six grams per gallon of dispensed fuel. The working capacity of 

the canister is approximately 240 grams. The basic components of 

the canister control system are shown in Figure A-4. The ported 

vacuum purge control valve is from a 1978 Chevrolet Impala evaporative canister, while the two fuel tank vapor valves (two are 

used to reduce the pressure drop during the refueling operation) 

are carburetor bowl valves from a 1978 Impala. Using two fuel tank 

vapor valves results in fillpipe pressures as low as two inches of 

water pressure during refueling. The fuel tank vapor valves are 

also controlled by manifold vacuum such that the vapor valves 

are closed when manifold vacuum is present at the control port. 

Atlantic Richfield Company 

Figure A-5 shows the fillpipe seal which ARCO has developed 

and tested for durability. Tables A-2 and A-3 are typical of the 

durability results obtained with this seal. Figure A-6 is an 

example of a prototype combination fillpipe/nozzle seal which has 

been developed and evaluated by ARCO. 

Ford 

The vehicles which Ford has used for refueling loss testing 

are shown in Table A-4. A single 4.35 1 canister is used in the 

Mustang, while a duel canister system, 829 ml and 3.4 1, are used 

for controlling carburetor vapors and diurnal/refueling losses, 

respectively, in the Pinto. The purge systems for the Mustang and 

the Pinto are shown in figures A-7 and A-8. 

Figures A-9 and A-10 are plots of canister loading versus test 

procedure sequence. These plots indicate that Ford's refueling 

loss control system is quite sensitive to the particular test 

procedure which is used to quantify the refueling control/exhaust 

emission interaction. 
P.35 

A-3 

Table A-l 

Vehicle Descriptions 

Fuel Tank 

Engine Displacement/ Capacity 

Make Model Configuration Control Systems (gallons) 

Chevrolet Caprice 5.0 litre (305 CID)/V-8 Ox. Cat., AIR, EGR 

Ford Pinto 2.3 litre (140 CID)/L-4 3-Way, Ox. Cat., 

AIR , EG R 

Plymouth Volare 3.7 litre (225 CID)/L-6 Ox. Cat., AIR, EGR 

Chevrolet Chevette 1.6 litre (98 CID)/L-4 Ox. Cat., AIR, EGR 

21 

13 

18 

12 

0 

.0 

0 

5 
P.36 

Table A-2 

FILLPIPE MODIFICATION 

ROTARY SEAL-CR 7538 

LEAK RATE AS AFFECTED BY 

FILLNECK PRESSURE AND WEAR 

NO. OF SPOUT 

INSERTIONS 

0 

100 

100 

100 

100 

100 

100 

100 

100 

100 

100 

TYPE 

SPOUT 

Smooth 

Rough 

Smooth 

Rough 

Smooth 

Rough 

Smooth 

Rough 

Smooth 

Rough 

CUMULATIVE 

INSERTIONS 

0 

100 

200 

300 

400 

500 

600 

700** 

800 

900 

1000 

FT3/MIN LEAK * 

@ 5" W.C. 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

e 15" w.c , 

0.00 1 

0.00 1 

0.00 1 

0.00 1 

0.00 1 

0.00 1 

0.00 1 

0.00 1 

0.002 

0.002 

0.002 

* Leak rate average of six nozzle insertions. 

** Expected number of insertions during vehicle life. 

RGJ:ip 

7/13/78 
P.37 

Table A-3 

FILLPIPE MODIFICATION 

ROTARY SEAL-CR 7538 

EFFECT OF LIQUID AND VAPOR GASOLINE 

SOAK ON SEAL ID AND LEAK RATE* 

HOURS OF 

LIQUID 

SOAK 

0 

16 

35 

-

-

-

-

-

-

_ 

TOTAL WEEKS 

OF VAPOR 

SOAK 

0 

0 

o 

2 

3 

4 

5 

6 

7 

8 

SEAL 

ID,IN. 

.712 

.712 

.711 

.705 

.699 

.701 

.703 

.698 

.693 

.691 

FT3/MIN 

@ 5" WC 

0 

0 

0 

0 

0 

0 

.001 

0 

0 

.001 

LEAK** 

@ 15" WC 

0 

0 

0 

0 

.001 

.001 

.001 

0 

.001 

.002 

* Vapor and liquid soak at 72°F. 

** Leak rate average of nine nozzle insertions, 

RGJ:ip 

7/13/78 
Figur e A-l 

EVAPORATIVE AND REFUELING EMISSIONS CONTROL SYSTEMS 

*C 

REFUELING AND 

DIURNAL VAPORS 

M -

PURGE 

.CONTROL 

VALVE 

CONTROL VACUUM 

AIR BLEED 

CONTROL RESTRICTION l-i rf VALVE t ^V^ CARBURETOR BOWL VAPORS 

CARBURETOR VACUUM PURGE 

RESTRICTION 

VENT 

REFUELING EMISSIONS 

CONTROL CANISTER 

kj^-. ! < ^ CONTROL 

CARBURETOR 

EGR TVS 

VACUUM 

MANIFOLD VACUUM 

PURGE 

=n 

ECS CANISTER 
€ Figure A-2 

PURGE <§ 4 LITRE/MIN. WITH DIURNAL ADDITIONS 

ADSORPTION TO 35 g. FROM BREAKTHROUGH 

3.5 litre Canister (BPL-F3) 

DD 

1 

2 

3 

4 

5 

6 

GRAMS 

Purged 

89 

34 

29 

32 

32 

33 

Diurnal 

11 

14 

20 

22 

24 

--

320 

300 -

280 -

1 LA-4 = 40 litres = 10 min. 

5 LA-4's = 1DD = 50 min. 

t oo 260 ~ 

u 

o 

4-1 

W 

••-( 

§ 240 

c 

o 

cu 

2 220 

3 

PQ 

1st FTP5^>15 Min ;=^49 g. 

200 

180 

160 

158 g 

capacj 

30 60 90 120 150 

Time (Min.) 

180 210 240 270 31 
o 

Figure A-4 

Refueling System Carbon Canister 

Sunbird 

Carb. Bowl 

Fitting 

Chevy Carb. 

Bowl Valves 

0.047" Bleed 

To Fuel Tank 

Chevy Purge 

Valve, Drilled 

To 0.180" 

CarbonSide View Of Top Disc 

77777///!//'////// / 

^S.'F^'m 

i i 

Canister Dimensions 

6" High 

8" Diameter 

i—r -!—i-l/8 " Plexiglass 

Wire Mesh Glued To 

Bottom of Tube 

1" dia. x 1 3/4" long 

Plexiglass Tube 

Foam 

Foam 

Wire Mesh 

< -Fiberglass Air Filter 

Carbon: BPL-F3 

1550 grams 

4350 ML 
Figure A-5 

P.41 

FILL PIPE MODIFICATIONS 

ROTARY SEAL 

ROTARY SEAL 

TRAP DOOR 

LEAD RESTRICTOR 

FILL PIPE MODIFICATIONS 

ROTARY SEAL 

ROTARY SEAL 

TRAP DOOR 

SPOUT 

LEAD RESTRICTOR 
P.42 

Figure A-6 

NOZZLE / FILLPIPE MODIFICATION 

CONE SEAL 

LEAD RESTRICTOR 

TRAP DOOR 

SPOUT 

LATCH COLLAR 

CONICAL SEAL 

NOZZLE / FILLPIPE MODIFICATION 

CONE SEAL 

LEAD RESTRICTOR 

TRAP DOOR 

SPOUT 

LATCH COLLAR 

CONICAL SEAL 
r-l 

VACUUM ACTUATED PURGE 

VALVE AND TANK VAPOR 

INLET VALVES ARE SIMILAR 

TO CURRENT PURGE VALVES 

ON BOARD VAPCSTRECOVERY SYSTEM 

Mustan g 8Z18 & 8Z19 

Syste m A 

TANK.-VAPOR INLET VALVES 

VACUUM CLOSED 

PURGE VALVE WITH 

0.180 IN ORIFICE 

VACUUM OPEN 

FILL PIPE OPENING 

THIS VALVE CONTAINS 

A .OU7 IN. BY-PASS 

.ORIFICE FOR TANK RUNNING 

LOSES 

CARB BOWL 

VENT CONNECTION 

SERVICE STATION 

NOZZLE 

PURGE LINE TO 

PCV HOSE 

CARB BOWL 

VENT LINE 

PURGE SIGNAL 

X

--3/8"DI A 

TUBING 

(REPLACES CONVENTIONAL 

TUBING) 

•I+35O ML CARBON VOLUME 

OPEN CELL FOAM 

WIRE SCREEN 

FIBERGLASS 

CANISTER (REPLACES CONVENTIONAL CANISTER) 

ENGINE COMPARTMENT MOUNTED 

TANK VAPOR 

LINE Z. 

FUEL TANK 

CW 

c 

fD 

I 

CO 
ON BOARD vy. RECOVERY SYSTEM 

PINTO 8E79 & 8E121+ 

Syste m B 

Ot PURGE LINE TO PCV HOSE 

-t>- CARB BOWL VENT LINE 

VAPOR -PURGE 

TO PCVXLINE 

THRU BOTH .090" 

& .085" ORIFICES 

•+• PURGE SIGNAL 

.// 

>URGE LINE 

PURGE 

SIGNAL 

.085" 

(PROD. VLV.) 

^.090" REMOTE PURGE VLV. 

925 ML CARBON VOL. ' 

TANK VAPOR 

LINE 

3^+00 ML CARBON VOL. 

FUEL TANK 

OQ 

c 

H 

> 

1 

00 
P.45 

^ 

Procedure 02 Set 2 

• Mustang 5.CL (8Z18) 1973 +9 States 

Date 7-17-73 Test 29 

- U35O ol Canister, Tank ci Carb. Ecwl v/.l8C" Purge Orifice 

r I Grass of Vapor Purged (-), Absorbed (+) 

Figure A-9 

+55 I-9 8 I+27 I-50 I +35' -38 1+39 1+3 I .+95 I -7k \ +18 ! 

•If6 _ 

^ 

o 

• 0 

H 

X! 

5. 

co 

•H 

O 

Production 

Sys. Purge 

+ 5 _ 

o 

-3" 

++ _ 

ON BOARD SIS. 

.Feedgas 

Cms/Mi CO 

Bag 1,223 CO Gos. 

Bag 1 CO Gos. 

Bag 1 CO. Gas. 

BASELIKE SYS. Bag 1,25:3 CO Gos. 

Gms/Mi CO 

15.9 

205 

I o p « 

118 

9.* 

v^y 

rH 

Cl 

•H 

•P 

-ri 

c 

H O 

r H i j 

•H 3 

Ci. O 

n 

*-3. O 

0 u 

cseu 

H n 

^ 0 

r-i 

•x0 2 d: ' 

^ '-> 0 

H O 

r-i 

I J •-* 

3 a O !« 

-H 

H CJ 

OJ n • 

-.•^ C 

rH 

~ d 0 s 

,-* t, 0 

H ^0 

H 

t , ci 

3" q 

0 M 

= : 3 

- H 

H O 

on n 

=*i; O 

' rH 

^ - H 

O s . 

rf 

'-i O 

£-1 VO 

CO 

u 

1f\ 

r H ^J 

1 SJ 

rH O 

H 03 

r H 

&g 

O « 

~ 3 

T-f. 

H Q 

H O 

•H d 

. r^i 01 

• co 

•oJ O 

0 f* 

CNO . 

O 

•H :=: 

63 O 

00 1 

•H cn 

w 5 

,M 

-* t* 0 

3 C/J 

0 

rr. -P 

• 0 

H rc 

Test Sequence 
j 

Procedure #3 Set 2 

Mustang 5.0L (8Z19) 1978 If9 States ' ' 

Date 7-8 & 9-78 Tost #11*, 15

 : 

— H35O trd Canister, Tank & Carb. Bowl Vapors w/.l80" Purge Orifice 

I Grams of vapor, Purged (-), Absorbed (+•) 

I +30 I -33 I +77 I —**5

 J +22 I +3 I -17 ' +13 • 

H 

;-. 

o 

- • 

-p 

j . 

QJ 

-P 

[/J 

o 

o 

i.r\ m 

-3-

^5 J A A 

88 

rH 

ul 'T-i 

"P 

•rt 

ri M 

3^ 

r*-t to 

LO 

v \ <i> 

0 f. 

~ r fL, 

a J - CD 

«=5 f-i 

HH fX, 

rH 0) 

f>H W 

CO 

»s 

ON OH 

* 77 • 

A A 

rl 

o -P 

•H O 

CO W 

CO 

•d w 

Teut Stjouance 

t 

o 

• ca 

<H O 

rH CO 

L_ 

r^ 

1 

PM 

O 

O i/ \ 

8°° W O 

-P 

* ^fl 

r-t - ^ 

66 j 

76 i 

i 

1 

0 

•rl « 

CO O 

CO 1 

• -d w ri > w G 

y 

0 

•gb 

. 

4 

CO «J 

0 

• 1/ 1 

W -P 0 

rH r. -* 

1 On Board 1 

Baseline 

• 

Feedgas CO Grama Bag //l 

OQ 

e 

I 

TI 

cn 
100 

Ui 

UJ 

Ui 8 0 

< 

I o 

cc 

=> 

a. 

O

 6 o 

Figur e A-11 

DISTRIBUTION OP GASOLINE PURCHASES 

• • 

4 0 

Z 

UJ 

o 

cc 

a. 

in 

> 

< 

3 20 

• • 

• • 

• • 

• • 

• • 

• • 

• •• • 

• - • • » » • — 

3 0 4 0 SO 6 0 7 0 

PERCENT OF TANK CAPACITY 

—*-. 

8 0 

— *— 

SO 

— • 

100 10 2 0 

^i 
Figur e A-l2 

REFUELING EMISSIONS CONTROLLED 

100 

Q 

UJ 

_J 

_J 

O 

QC 

»-

2 

O 

O 

Ui 

2 

O 

Ui 

Ui 

2 

UJ 

a 

_J 

OC 

o £ 

_J 

< UJ 

cc 

8 0 

tiO 

4 0 

?o 

• • • 

••• • 

• • 

• • • 

** 

** 

** 

** 

** 

** 

** 

** 

10 20 3 0 4 0 SO 6 0 7 0 8 0 9 0 

REFUELING TEST REQUIREMENT FOR NO EMISSIONS. % of TANK CAPACITY 

— • 

IOO 

00