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# OAR Box 1830 Prepped by Ollie Stewart



### Document

Number: 

# 127 ) IV-C-9

3 Docket Number: 

# A-87-1 1

Printed 11/13/20087:20:58AM Sheet 12 7 of 232P. 2

-* ' ^ \ UNITE D STATE S ENVIRONMENTA L PROTECTIO N AGENC Y ^ ^ " 

# i a s

' / AN N ARBOR . MICHIGA N 4810 5

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### I T198 8 OFFIC E O F AI R AN D RADIATIO N Mr . Samue l A . Leonard , Directo r Automotiv e Emissio n Contro l Environmenta l Activitie s Staf f Genera l Motor s Corporatio n 3040 0 Moun

d Road Warren , M I 48090-901 5 Dea r Mr . Leonard : Thi s lette r i s a followu p t o conversation s m ystaf f hav e ha d wit h Genera l Motor s concerning on e o f the vide o tape s whic h G M submitte d a s par t o f it s comment s o n th e onboar d refueling proposal . Th e tap e i n questio n document s test s don e fo r G M b y Failur e Analysi s Associate s (FAA ) evaluating the possibilit yo f underhoo d fire s fro mdamage d refueling systems . I n the . tes t sequence , th e refueling vapo r hos e wa s disconnecte d fro

mthe refueling canister , whic h ha d bee n locate d unde r th

e hood , an

d re-route d s o a s t o en d immediatel y adjacen t t o a damage d spark plug wire . Th e vehicl e wa s refuele d wit h 1 5 gallon s o f fuel , th e nozzl e wa s returne d t o the fue l dispenser , an d the vehicl e subsequentl ywa s restarted . I n a vide o tap e o f th e hos e outle t unde r th e hood , the vapo r surrounding the en d o f the hos e wa s see n t o ignit e upo n engin e engagement . Th e vapo r continue d t o be emitte d an d bur n for th e approximatel y6 second s o f filming . I n addition , the hos e itsel f bega n t o burn almos t immediately . M ystaf f ha

d contacte d yo u t o as k ho w i t wa s tha t vapor s appeare d t o continu e t o flow fro mth e hos e eve n thoug h the refuelin

g even t ha

d ende d an

d the vapo r chec k valv e wa s closed . Yo u ha

d apparentl yreferre d th e questio n t o Mr . Ji m Pase k who , alon

g wit h Mr . Rober t Lang o f FAA , contacte d u s fo r followu p discussions . During th e discussions , Mr . Pase k an d Mr . Lang offere d severa l possibl e explanation s fo r th e event s show n o n th e video : (1 ) Th e vapor s flowing in the line durin g the refueling ha d sufficien t inerti a s o a s t o continu e t o flo w whil e the engin e wa s being started .P. 3

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" (2 ) Th e combustio n proces s woul d creat e a vacuu ma t the en d o f the hos e an

d dra w th e vapor s ou t o f th e line . (3 ) Th e evaporativ e ven t orific e wa s venting residua l tan k pressur e int o th e hose , sinc e the liqui d sea l woul d preven t ful l tan k depressurizatio n immediately . W e fin d non e o f thes e answer s t o b e full ysatisfactory . Th e firs t tw

o reason s ar e inconsisten t wit h th e fac t tha t th

e refueling vapo r shutof f valv e on the othe r en d o f the lin e ha

d bee n close d sinc e th e en d o f th

e refueling operation . A s fo r the third explanation , venting a t the hig h rat e see n in the vide o woul d hav e equilibrate d the tan k i n a few seconds , mos t likel ybefor e the engin e star t sequenc e eve n began . I f th e venting wer e slow , then i t i s difficul t t o understan d ho w th

e larg e bur n rat e wa s sustained . Furthermore , i f venting through th e evaporativ e ven t orific e wa s capabl e o f releasing suc h a hig h volume o f vapor s a t the relativel ylow in-tan k pressure s generate d during refueling , the n muc h highe r vapo r flow rate s coul d occu r fro

mcurren t fue l tan k ven t line s during period s o f vehicl e operatio n a s fue l tan k temperature s increase . A s yo u ar e undoubtedl yaware , fairl yhig h in-tan

k pressure s can occu r unde r suc h conditions , muc h highe r than the liqui d sea l system produce s during refueling . Thus , th e potentia l hazard fro ma disconnecte d vapo r lin e woul d appea r t o be greate r wit h curren t vehicle s than fro

mrefuelin

g contro l syste

madditions . Sinc e the safet yo f bot h curren t an d propose d contro l system s i s a

n importan t concern , I a m writing t o reques t a furthe r explanatio n o f th e vapo r releas e during thes e tests . Pleas e identif ypossibl e source s o f vapor s an d mechanism s fo r releas e fro

mthe refueling ven t hos e i n quantitie s sufficien t t o produc e the observe d fire . Also , pleas e addres s th e mean s b ywhic h th

e vapo r hos e itsel f an d th e spark plug wire s wer e abl e t o ignit e almos t immediately . Our experienc e indicate s tha t i t i s normall yquit e difficul t t o ignit e heav yrubbe r hosing an

d wiring suc h a s picture d i n your system . Finally , pleas e describ e how th e car wa s conditione d prio r t o th e refueling test , an d whethe r the ca r wa s drive n or standing stil l whil e th

e engin e wa s bein

g run . Sinc e we ar e alread yin the mids t o f ou r review o f comments , an

d sinc e safet yconcern s ar e o f paramoun t importance , I reques t your promp t repl yt o thi s matter . I woul d appreciat e a respons e befor e Marc h 30 , 1988 .

.e s L . Gray , Directo r / Emissio n Contro l Technolog yDivisio n

cc : Docke t A-87-1 1