p.1 

OAR Box 1147 

Prepped by Ollie Stewart 

Document Number: 

197)IV-E-71 

Docket Number: 

A-87-11 

Printed 4/22/2008 2:42:57 PM Sheet 197 of 242 
P.2 

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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

ANN ARBOR. MICHIGAN 48105 

OFFICE OF 

AIR AND RADIATION 

SEP 2 2 1938 

MEMORANDUM 

SUBJECT: 

FROM: 

TO: 

Briefing on General Motors' Onboard Hardware 

John F. Anderson, Senior Proj 

Standards Development and Suppo 

Public Docket A-87-11 

ject Manager Sji^i''/LmU--^_ 

pport Branch / 

On September 16, 1988, Mr. Jim Pasek and Mr. Mike Lombardo 

of General Motors briefed EPA on GM's evaluation of onboard 

refueling hardware similar to the simple system built by EPA. 

EPA representatives were myself, Chet France, Peter Hutchins, 

Dave Bartus and Paul Laing. 

The briefing presented by GM is attached. During our 

discussions, a number of questions arose where further 

supporting information was needed to aid in our understanding 

of the presentation. As a result a followup letter will be 

sent to GM. 

Attachment 

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P.3 

Onboard Refueling Vapor Control System 

Evaluation of EPA Flowing Liquid Seal 

September 16, 1988 

presented by 

Michael S. Lombardo 

Environmental Activities Staff 

General Motors Corporation 

• _ . m-\ na /• ie\f 
P.4 

The EPA-designed liquid seal onboard refueling control system was 

evaluated by General Motors using several typical fuel system 

evaluation tests. The results showed: 

Liquid fuel can enter the vapor vent line in typical vehicle 

maneuvering situations. 

The EPA fuel system, which does not use tank vapor pressure 

controls, can generate about 20 times more vapor than a fuel 

system with tank pressure control. 

EPA's liquid seal design performed poorly in controlling partial 

tank fills during SHED measurements. 

Fill quality is poor. Excessive premature shutoffs occur, and the 

design is sensitive to variations in fill conditions. 
P.5 

Evaluation Procedures 

EPA: 

Bench refueling measurements, complete fills only 

GM: 

Bench refueling measurements, complete and partial fills 

Vehicle maneuvering 

High temperature/high load 

Fill quality 

Fuel expansion 

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P.6 

Refueling Emissions Measurement 

At the time of testing, there was no test procedure with which to 

evaluate refueling emissions control performance. 

Bench test, canister purged with vacuum pump between tests. 

Results of measurements with EPA-system equipped vehicle: 

Complete fills (10% to 95% nominal capacity fill) showed 

refueling emissions below 0.1 gram per gallon. 

Partial fills (10% to 50% nominal capacity fill) showed refueling 

emissions between 0.4 and 1.2 grams per gallon. 

"Topping off" (95% to 100% nominal capacity fill) produced 

refueling emissions between 0.4 and 0.9 grams per gallon. 

FA<;/AFOMSL9/16/88 
SHEDHC 

g/gal 

1.3 

1.2 

1.1 

1.0 

0.9 

0.8 

0.7 

0.6 

0.5 

0.4 

0.3 

0.2 

0.1 

0 

Measured Refueling Losses 

10% to 95% fills 

EPA system, bench purged canister 

I

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8.5 RVP 

9.2 RVP 

11.5 RVP 

Fill Rate, gpm 10.0 10.0 3.9 9.8 5.3 9.7 9.9 

TJ 
SHEDHC, 

g/gal 

1.3 

1.2 

1.1 

1 

.9 

.8 

.7 

.6 

.5 

.4 

.3 

.2 

.1 

0 

Measured Refueling Losses, Partial Fills 

EPA system, bench purged canister 

9.2 RVP 

9.8 RVP 

11.5 RVP 

10% to 50% Fill 50% to 95% Fill 95% to 100% Fill 

TJ 

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P.9 

Vehicle Maneuvering 

Vehicle maneuvering tests evaluate the ability of the fuel system to 

keep liquid fuel from entering the vapor vent line. 

Tests include various in-use driving patterns such as abrupt lane changes 

and sudden acceleration and deceleration. 

The EPA-system equipped vehicle does not control liquid loss to the 

vapor vent line in these tests. 

CAC/Acr/Mci Q/ifi/aa 
P.10 

Liquid Loss during Typical Vehicle Maneuvering 

Liquid Loss in Fuel Tank Vapor Vent Line, g 

(9 psi RVP fuel) 

Test 

1 lap of circle 

track, 1 lap of 

straightaway 

Right-hand and lefthand lane changes 

0-80-0 acceleration 

and braking 

Return to buildings 

EPA-System 

Equipped 

A-car 

52 

111 

126 

4 

Production 

A-car 

0 

2 

4 

0 

TOTAL 293 

CAC/AC*~/I\/1CI o/i<;/n« 
P.11 

Hot Driving under Load 

Tests are conducted under extreme conditions of ambient temperature 

and engine load to determine liquid and vapor loss from the fuel tank 

under these conditions. 

An EPA-system equipped vehicle and a production vehicle were driven 

over the same routes simultaneously. The routes included mountain 

and city driving in Arizona. 

The EPA-system equipped vehicle generated 20 times more vapor than 

a production vehicle with a tank pressure control valve. 

FAS/AEC/MSL 9/16/88 
Liquid Loss from Fuel Tank, g 

South Mountain and Phoenix City Traffic 

(9 psi RVP fuel) 

EPA-System Production Production 

Equipped A-car A-car 

A-car w/oTPCV w/TPCV 

459 23 

695 30 

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Vapor Loss from Fuel Tank, g 

South Mountain and Phoenix City Traffic 

(9 psi RVP fuel) 

EPA-System Production Production 

Equipped A-car A-car 

A-car w/oTPCV w/TPCV 

947 425 

1362 63 

FAVAEC/MSL 9/16/88 
P.14 

Fill Quality 

Fill quality tests evaluate how fuel systems function during refueling 

events. 

These tests determine fill quality under a variety of refueling 

conditions, measuring premature shutoff, spitback, consistent fill 

volume, and other factors. 

The fill quality of the EPA-system equipped vehicle was poor. 

Premature shutoffs were frequent, spitback occurred with high 

volatility fuel, and the tank could not be fueled at a gasoline flow rate 

of 12 gallons per minute. 

With poor fill quality, customer satisfaction is likely to be low, possibly 

leading to tampering of the fuel system components. 

rAf/»rriMf l OMC/Q Q 
P.15 

Fuel Expansion 

The fuel expansion tests determine the presence of leaks in fuel systems 

due to thermal expansion of the fuel when the tank is full. 

While the vehicle is held statically at a variety of attitudes, heat is 

applied to the tank. 

No fuel leaks occurred in the EPA-system equipped vehicle. 

EAS/AEC/MSL 9/16/88 
' " • - '• ' TM— — • - , r, , . ... . . .. , , -_ ^ ^ P 1R 

Conclusion 

The EPA onboard refueling control system design is inadequate for 

production vehicles. 

- Liquid fuel can enter the vapor vent line. 

- Vapor generation rates are high. 

- Refueling emissions are high with partial fills. 

- Fill quality is poor. 

EAS/AEC/MSL 9/16/88