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OAR Box 1830 

Prepped by Ollie Stewart 

Document Number: 

174) IV-C-141 

Docket Number: 

A-87-11 

Printed 11/13/2008 7:21:00 AM Sheet 174 of 232 
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*«>*„ HZ-c-/y/ 

£ _ _

 Ti UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

ANN ARBOR. MICHIGAN 48105 

OFFICE OF 

AIR AND RADIATION 

DEC I 4 1933 

Mr. Kelly Brown, Executive Engineer 

Noise, Emissions, Fuel Economy Planning 

Ford Motor Company 

The American Road 

Dearborn, MI 48121 

Dear Mr. Brown: 

Thank you for your November 7, 1988 letter concerning the 

performance of the refueling control hardware which we have 

tested on a Ford Taurus fuel tank. As you know, we believe 

that the performance of this hardware demonstrates the 

successful application of our simplified refueling control 

concept to the Taurus tank. Hopefully I can address some of 

the questions which still exist in your mind. 

You first indicated some concern that the performance of 

our system may be overly sensitive to the precise dimensioning 

of the fillpipe orifice. This is not the case. As we 

indicated in our briefing, we obtained successful 

configurations that worked at both 3 and 10 gallons per minute 

dispensing rates employing orifice sizes from as small as 0.85 

inch diameter all the way up to the largest size tested, which 

was 1.05 inches. Since during this process we were doing a 

good deal of exploratory testing, it is not at all surprising 

that we also tested a number of configurations which did not 

perform successfully. The fact that such things as the shape 

of entry and exit surfaces for flow discontinuties affects 

turbulence levels and flow resistance does not in any way 

indicate sensitivity to "minor changes." As I am sure you are 

aware, in a production system one would not use special inserts 

to obtain reduced diameters, but would incorporate the 

appropriate reduced pipe diameter directly into the fillpipe 

design. 

I was somewhat surprised at your statements about the 

emissions performance of this system still being in doubt 

because some of the measurements were taken with the canister 

outside the SHED. You are as aware as we are that, short of 

the breakthrough point, canister emissions are essentially 

zero. We have seen no detectable difference in emissions when 

the canister is inside the SHED compared to when it is outside 
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the SHED. In any event, as you also know, final tests on our 

selected configuration were all done with the entire system 

inside the SHED. Of this series of six consecutive tests, all 

results were at or below 0.05 grams per gallon, meeting our 

proposed standard with a margin of safety of 50 percent or 

more. These tests were all done according to the requirements 

of our draft procedures including 10 percent initial fill, etc. 

Another significant issue in your letter concerns adequate 

rollover performance for the vapor control valve. There is no 

doubt that the valve which Ford tested had not been designed or 

adequately tested for full rollover protection. Whether you 

wish to attribute the problems you experienced to a "defective 

seal" (our term) or a "prototype design defect" (the valve 

supplier's term), is of no particular concern to EPA. The 

redesigned valve produced by the vendor for our use did pass 

rollover tests, and we have offered to show you video tapes of 

the test. You are incorrect in your understanding that other 

tests run over the same weekend were unsuccessful. As we have 

previously shared with you, we had earlier had some problems 

with the valve function, both for refueling shutoff and for 

rollover. These problems were due to the fact that prototype 

parts, being hand machined rather than molded, can only be made 

of plastics which are not totally stable when exposed to 

gasoline for extended periods. We were not aware that such 

prototypes are intended for limited testing only and found that 

the valve experienced gradual swelling and subsequent sticking 

which prevented it from closing properly. Upon being air 

dried, the valve regained full function. 

We understand such difficulties to be quite normal when 

dealing with prototype materials. For more extended use, the 

valve would have to be made from production type molds, which 

are too expensive when only one or two valves are needed, or 

machined from metal parts. However it is dealt with, this is a 

materials availability problem totally unrelated to the ability 

of a production version of this valve to function properly over 

the full life of a vehicle. The availability of suitable 

production materials is clearly demonstrated by the many 

plastic valves already in widespread use. 

You also raised a point about the occurrence of situations 

where an assumed suitable production version of a rollover 

valve was either defective or damaged in a severe crash. This 

concern is somewhat surprising, since the refueling vapor vent 

line on existing Ford vehicles, which our system replaces, has 

no protection whatsoever against fuel leakage. Thus, any 

valve, even if only partially functional, would greatly reduce 

any risk associated with fuel escaping from this large tank 

opening. If there were no valve at all, the risk would be no 

greater than on your current production vehicles. In addition, 

your current refueling vent line is located in a relatively 

vulnerable crash zone around the fillneck opening and is much 

more liable to be damaged in a crash than would our system, 

which uses a shorter line well protected under the vehicle. 

Finally, standard industry practice today is for all production 
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rollover valves to be individually tested before delivery. 

This makes it extremely unlikely that a defective valve would 

ever be installed on a vehicle. Overall, it is quite evident 

that a vapor vent system such as we have designed improves the 

safety of current fuel tank systems. Your concern suggests 

that the standard against which you are measuring our hardware 

is one which even current production cars do not meet. 

Overall, we do not agree with your conclusion that further 

work is needed to demonstrate a satisfactory system. We do 

agree that further work is needed on your version of our system 

to identify the difficiencies which have caused you to 

experience such poor results. We have demonstrated that 

"substantial redesign" of components, as you put it, is not 

needed. Clearly, "substantial redesign" was not even possible 

in the roughly two week period which was required for us to 

adapt our system to the Taurus tank. This is not to say that 

an even better, more carefully optimized, set of components 

could not be developed. That simply was not the intent of our 

program. Our goal was to demonstrate the basic applicability 

of our simplified design to your products, and that has clearly 

been done. 

Lastly you raised the question of the effect of our system 

on running losses due to the lack of a pressurized tank with 

our approach. You are correct in observing that the running 

loss data we have collected indicate a widespread lack of 

control of running losses based on current vehicle designs. 

That is not surprising given the lack of attention to running 

loss control in vehicle development and certification. What is 

significant, however, is the ability of some of the tested 

vehicles to control the release of running loss vapors, even 

with unpressurized tanks. We do not believe that high tank 

pressures are needed to successfully deal with running loss 

control during the ozone season. The modeling results you have 

given to us indicated a relatively small impact of tank 

pressurization for 9.0 psi RVP fuel. We think that the 

potential for safety risks associated with high pressure tank 

systems is a significant drawback of such an approach. 

Once again, thank you for your letter. We look forward to 

continued discussions with you and your staff on these areas. 

Hopefully we can soon resolve the open issues to our mutual 

satisfaction. 

Sincerely yours, 

Charles L. Gray, 

Director 

Emission Control Technology Division 

6632W