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# OAR Box 1830 Prepped byOllie Stewart



### Document

Number: 

# 188 ) IV-C-15

5 Docket Number: 

# A-87-1 1

Printed 11/13/2008 7:21:01 AM Sheet 188 of 232> A v i UNITE D STATE S ENVIRONMENTA LPROTECTIO N AGENC Y PJ

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AN N ARBOR . MICHIGA N 4810 5

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Mr . Jame s E . Pasek , Manage r cP c °i?& Automotiv e Emissio n Contro l ^^v ^ Environmenta l Activitie s Staf f ^o^f-c-^ ' Genera l Motor s Corporatio n £^ M V .<$£

> Genera l Motor s Technica l Cente r ^< o riC)& S 3040 0 Moun d Roa d a$ & , v^\.^\ Warren , M I 48090-901 5 G ^ cVy : '.'.-
- Dea r Mr . Pasek : Thi s i s i n respons e t o you r recen t lette r o f Januar y11 , 1989 , concernin g th e performanc e o f refuelin g controls . I n you r lette r yo u raise d som e question s whic hI wil l respon d t o below . However , sinc e you r lette r wa s i n respons e t o m y earlie r correspondenc e o f Decembe r 14 , 1988 , I mus t rais e severa l othe r matter s first . Thes e concer n specifi c request s i n m yDecembe r 14 , 198 8 lette r whic hyo u didn' t addres s i n you r response . First , I mad e tw o specifi c request s fo r clarificatio n o f earlie r informatio n whic hG M ha d supplie d t o EPA . Thes e wer e fo r a n explanatio n o f a n apparen t inconsistenc yi n you r fil l tes t result s concernin g th e occurrenc e o f spitbac k fro myou r syste man d fo r a descriptio n o f th e "functiona l checks " whic h G Mperforme d t o verif yprope r performanc e o f you r tes t ven t valve . Bot ho f thes e item s dea l wit hke yquestion s i n th e hardwar e evaluation s whic hG M ha s performed . I woul d therefor e appreciat e you r respons e t o thos e requests , whic hwer e describe d mor e completel yi n mypreviou s letter . I als o reiterate d EPA' s reques t fo r copie s o f 1 9 specifi c Genera l Motor s Unifor mTes t Specification s (GMUTS ) relate d t o testin g o f fue l an d evaporativ e systems . A s I noted , w e ar e awar e tha t you r staf f ha d collecte d copie s o f th e requeste d documents , bu t tha t G M ha d decide d t o withhol d the mfro mEPA . Onc e again , I reques t copie s o f thes e documents .P. 3

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- Turning t o your curren t letter , yo u firs t propose d a n updat e o n our activitie s relate d t o refueling contro l hardwar e sinc e April , 1988 . A s i t relate s t o Genera l Motors ' fue l tan k systems , we have don e no newwork beyon d tha t alread

y reported . We have applie d simila r component s t o a Ford Tauru s fue l tank , an

d thi s ha s als o bee n documente d in the docket . Tha t systemused a large r caniste r an d involve d evaluation s o f improve d rollover/ven t valves , bu t neithe r o f thes e change s represen t significan t conceptua l departure s fromwha t wa s don e t o the G

M fue l tank . We woul d be glad t o showyo u thes e component s i f yo u desire , sinc e I understand , tha t a s a resul t o f Mr . Stempel' s Decembe r 13 , 198 8 meeting wit hAdministrato r Thomas , tha t G

M i s preparing a comprehensiv e briefing for u s on your technica l an

d safet yconcerns , we wil l plan t o bring thes e component s wit hu s a t the time o f tha t presentation . Als o a s par t o f your briefing , EP Awoul d appreciat e a n updat e on your onboard hardwar e evaluation . I appreciat e your suppor t for our proposa l t o contro l fue l RVP t o 9. 0 psi . I t appears , however , tha t som e o f m

y statement s abou t running losse s i n tha t contex t ma yhav e bee n somewha t confusing . I indicate d that , whe n comparing you r estimate s o f increase d vapo r generatio n fro munpressurize d fue l tank s t o thos e o f Ford , tha t the number s yo u foun d fo r 9 RV

P fue l wer e no t excessiv e give n the rarit yo f th e condition s involved . I wa s attempting t o indicat e tha t condition s o f significantl yincrease d vapo r generatio n rates , i f sufficientl y rare , need no t caus e running los s emission s fro mthe vehicl e sinc e th

e caniste r wil l be abl e t o contai n exces s vapor s periodicall yfor subsequen t purging unde r mor e favorabl e conditions . Our running los s measuremen t dat a indicat e tha t som e vehicle s wit hnon-pressurize d tank s ar e alread yabl e t o contai n tan

k vapor s a t ambien t temperature s u p t o 95 ° F . Althoughyo u hav e no t give n u s ful l detail s o n the condition s leading t o your running los s data , w e d o knowtha t they include d ambien t temperature s abov e 100°F , exceeding the 90t h percentil e uppe r limi t valu e o f 96° F for clas s C volatilit y areas , an

d extende d mountai n driving , whic hwoul d greatl y increas e fue l tan

k temperatur e ris e above ambient . Whil e w e ar e indeed concerne d abou t the contro l o f running losse s fo r extreme or nea r wors t cas e conditions , ther e ar e likel yt o alway s be some extreme case s wher e i t become s essentiall y impossibl e t o contai n al l generate d vapors . I n a wel l designe d system , thes e condition s woul d no t produc e direc t vapo r emissions , bu t woul d eventuall yoverload th e canister , leading t o indirec t releas e o f som e emission s fro

mthe canister .P. 4

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- W e stil l believ e there , i s caus e fo r concer n abou t safet y risk s associate d wit hoperating wit hsignifican t fue l tan k pressurization . Yo u indicate d tha t operating wit hpressure s u p t o abou t 4 0 inche s o f wate r woul d be helpful . Suc hpressures , i f no t properl ycontained , coul d caus e larg e amount s o f fue l t o b e ejecte d upo n removing the fue l cap . Th e experience s o f Ford wit hfue l expulsio n fro mambulanc e fue l tank s i s a clea r exampl e o f thi s risk . Thus , we continu e t o believ e tha t significan t fue l tan k pressurizatio n i s undesirable . Lastly , yo u aske d fo r informatio n on ' wha t refueling conditions , in term s o f amoun t o f fil l an d nozzl e clickoffs , manufacturer s woul d be require d t o control . The requiremen t whic hw e hav e propose d i s fo r a t leas t a n 8 5 percen t fueling fro m1 0 percen t ful l t o 9 5 percen t full , utilizing automati c shutoff . Thi s requiremen t i s easil yme t withou t the us e o f multipl e clickoffs . W e woul d als o expec t tha t a wel l designe d system woul d significantl ycontro l emission s during topping of f operations . Eve n thoug hw e disagre e on the performanc e o f simplifie d hardwar e designs , bot hour testing an d your s hav e confirme d thi s t o be the cas e fo r prototyp e refueling contro l systems . Our partia l fil l test s demonstrate d 9 5 percen t or greate r contro l during fill s fro m9 0 percen t full , including topoffs . I believ e thi s informatio n respond s t o th e question s i n your January11 , 198 9 letter . W e look forward t o your respons e t o th e ope n issue s mentione d abov e an d t o the upcoming technica l briefing fro mG M staff . jerely , Ches/ter^J . France , Chie f Standard s Developmen t an d Suppor t Branc h

cc : Docke t A-87-1 1 6744 W