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OAR Box 1830 

Prepped by Ollie Stewart 

Document Number: 

167) IV-C-134 

Docket Number: 

A-87-11 

Printed 11/13/2008 7:21:00 AM Sheet 167 of 232 
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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

I A\l/X. .» ANN ARBOR. MICHIGAN 48105 

OFFICE OF 

CTO O Q inOQ

 AI R AN D

 RADIATION 

Mr. Donald Buist, Director 

Automotive Emissions & Fuel Economy Office 

Ford Motor Company 

The American Road 

Dearborn, MI 48121 

Dear Mr. Buist: 

Thank you for the briefing which you and your staff 

presented to Dick Wilson, myself and other EPA staff on 

September 26, 1988 concerning the status of Ford's evaluation 

of the simplified onboard control concept used in the EPA 

demonstration hardware. This letter is intended to summarize 

some of the major conclusions from your presentation and 

associated discussions as we understood them. I have also 

summarized what we believe to be. the followup items agreed to 

at the conclusion of your presentation. 

We appreciate the amount of effort which Ford has invested 

in its investigations of this hardware concept. At the same 

time, as we discussed during your presentation, there appear to 

be some key areas which have not yet been dealt with in 

developing a well performing system. This was clearly evident 

in your evaluation of overall fill quality for the system which 

Ford has developed. You indicated that the system which you 

installed on a Ford Taurus could, not fill successfully at 

dispensing rates above 7 gal/min and that the F-250 light-duty 

truck could do so only after the fill pipe was raised some five 

inches. You also identified large numbers of premature 

shutoffs as a problem. Neither of these two problems are 

present on our hardware, although we had to deal with both of 

them in the course of our development program. 

From your presentation we identified two areas which you 

had not evaluated and which may be responsible for these 

problems. First, your vapor handling hardware downstream from 

the fuel tank is causing excessive backpressure in the tank 

during refueling. The canister appeared to be the most likely 

cause and you agreed to some followup work in this area. Based 

on our experience, the pressures you are using are simply too 

high to allow satisfactory fill performance, and it was a 

surprise to us that you had not already taken steps to lower 

your operating backpressure. Raising the fillpipe, using >.two 

vent valves, or lowering the dispensing flow TNtr.ate^0-a'tl* not 

appropriate solutions to this problem. b^L^-'. 
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The second problem we identified was the fact that you had 

not made any modifications to the anti-spitback ball valve. 

Our own experience with this valve, as described in our 

presentations on our hardware, was that the specific gravity of 

the ball had to be increased somewhat in order to prevent 

freguent premature shutoffs. However, Ford has used the valve 

with no modifications and no investigation of the effect of 

this valve on fill quality. You also agreed to followup work 

on this component. 

The above deficiencies in the Ford design of a simplified 

system need to be corrected before a meaningful evaluation can 

be completed. Prior to that, your conclusions about the 

performance of such systems on Ford products are premature. We 

know of no unique characteristic of Ford vehicles, nor did you 

identify any, which would impede the use of the basic simple 

system concept on your vehicles. In fact, at least for your 

F-250 light-duty truck, implementation should be even simpler 

than on the General Motors vehicle which we used because of the 

relatively straight fill pipe configuration of the stock system. 

Another important aspect of your presentation was a video 

tape of the rollover testing, which you performed on the 

enlarged vent valve. This tape showed that the hand modified 

valve which you used did not seal properly during rollover, and 

you indicated your belief that obtaining satisfactory and 

reliable rollover protection for an enlarged valve was a 

serious problem. We do not believe this to be the case. 

It was not at all surprising that the modified valve did 

not seal well during rollover tests. The valve was hand 

modified and not manufactured with the precision needed for 

tight sealing. It had not been intended to pass a rollover 

test, since the valve manufacturer had assured us that this 

requirement was easy to satisfy with production-type hardware. 

You indicated some contact with the valve supplier, wherein 

they indicated to you that even our recently procured prototype 

two-stage vent valve might not pass rollover testing. We have 

since reviewed this matter with them, and they have assured us 

that rollover protection was not difficult, and that the new 

valve which we procured was in fact tested extensively for 

rollover function before being supplied to us. In attempting 

to explain how you may have gotten an incorrect impression, the 

valve supplier indicated that it may have arisen from his 

comments that a production system would likely perform better 

than the prototype because production systems would have 

smoother wall surfaces and could have a float designed for 

greater closing power than the prototype. 

The valve supplier also indicated that the prototype valve 

which we procured was evaluated for its ability to prevent the 
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escape of liquid from the tank during sloshing due to such 

things as sharp cornering, sudden stops, etc. There were no 

conditions identified during which the valve passed liquid fuel 

(other than entrained fine droplets) out of the tank. Thus, 

another of the concerns you raised appears to be resolved. 

Your briefing contained a substantial amount of both 

modeling and test data related to vapor generation rates and 

the performance of your current evaporative controls. The 

modeling results were quite interesting, however we ended with 

a number of unanswered questions which you agreed to deal with 

in a future meeting. It appears from your presentation that, 

at 9 RVP, the difference in vapor generation between the stock 

Taurus tank and the simplified refueling system is less than 10 

percent. From your test data we note the fact that the stock 

evaporative" control system on the Taurus vehicle was able to 

nearly pass the double high temperature diurnal requirement of 

our new draft regulations, and that you believed that only a 

small increase in canister size would be required to satisfy 

our proposal. You agreed that the vapor storage capacity 

required to handle refueling emissions was very similar, and 

therefore that improved evaporative systems and refueling 

control systems would require similar canister sizes. You also 

agreed that, in order to handle possible extreme running loss 

conditions and not vent to atmosphere (even with 9 RVP fuel), 

the tank vent valve capacity for either evaporative or 

refueling controls would have to be similar. 

Finally, we had discussions about your conclusions as to 

the components required to control either refueling or only 

evap and running losses. We did not believe that your 

conclusions were adequately justified. Differences between 

your position and ours were not fully resolved, however. Much 

of this was due to your views on the workability of the simple 

refueling control system. Thus, resolution of these questions 

must wait until you have completed your followup hardware work. 

Thank you again for your presentation, we found it 

constructive. We look forward to an early followup meeting 

about your modeling and to continuing interaction on the other 

points reviewed above. If you have any questions on any of 

these areas, please feel free to contact me about them. 

Sincerely yours, 

Charles L. Gray,ytfr. 

Director • / 

Emission Control Technology Division 

cc: A-87-11 

A-85-21 

6421W