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# OAR Box 1830 Prepped by Ollie Stewart



### Document

Number: 

# 163 ) IV-C-13

0 Docket Number: 

# A-87-1 1

Printed 11/13/20087:21:00AM Sheet 163 of 232P. 2 

## 1 2 ~c - ii o | A r * UNITE D STATE S ENVIRONMENTA L PROTECTIO N AGENC Y l-SS-ir /

AN N ARBOR . MICHIGA N 4810 5

OFFIC E O F AI R AN D FIADIATIO N SL; ' 2 1 1988 Mr . Jame s E . Pase k Aut o Emissio n Contro l Environmenta l Activitie s Staf f Genera l Motor s Corporatio n • 3040 0 Moun

d Roa d Warren , M I 48090-901 5

Dea r Mr . Pasek : Thank yo u fo r the briefing o f Septembe r 16 , 198 8 o n you r evaluatio n o f Genera l Motors ' simplifie d onboar d refueling contro l system

patterne d afte r the systemdesigne d b yEPA . A s w e hav e indicate d o n previou s occasions , EPAi s mos t intereste d i n evaluation s o f thi s concept . Thi s lette r i s intende d t o confirmsome o f the observation s whic h w e mad e during th e briefing a s wel l a s t o pas s on some specifi c question s whic h remai n unanswere d following you r presentation . Perhap s mos t importantly , i t became increasingl yclea r t o u s a s you r briefing progresse d tha t the hardwar e whic h yo u evaluate d perform s significantl ydifferen t fro mour equipment . Thi s can be seen , fo r example , i n you r testing o f fil l qualit y and , o f partia l fil l performance . Accordin g t o you r presentation , fil l qualit ywa s degrade d du e t o frequen t prematur e shutoff s an d the occurrenc e o f spitback . Additionally , yo u foun d a significan t los s o f contro l fo r partia l fil l operations . A s w e discusse d wit h you , neithe r o f thes e two problem s hav e occurre d wit h our hardware . Avery high qualit yfill , significantl yimprove d ove r eve n the stoc k fue l tank , ha s bee n characteristi c o f our design . A s fo r partia l fills , we hav e conducte d partia l fil l testing an d foun d tha t ou r systemwork s well , unlik e yours . Therefore , i t appear s tha t the G M systemi s differen t fro mthe EPAsysteman d tha t result s fro

myour testing , whil e instructive , can no t b e take n t o appl yt o our design . W e wer e no t abl e t o determin e the caus e o f the poo r performanc e o f th e G M design base d upo n th e limite d informatio n i n you r presentation . Ther e ar e severa l difference s betwee n

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you r hardwar e an

d ours , including th e placemen t o f the valve , hos e routing , an

d caniste r design . Al l o f thes e factor s affec t the operating backpressur e in th e tan k during refueling , an d mus t be chose n s o a s t o giv e satisfactoryfil l performance . I t appear s tha t yo u hav e use d sizing parameter s selecte d b yEPA withou t adjustmen t fo r the hardwar e difference s betwee n the tw o systems . I n orde r t o spee d th e resolutio n o f the problem s wit h you r system , we reques t tha t yo u provid e your hardwar e t o u s fo r some compariso n testing . Thi s woul d involv e some paralle l test s o n bot h system s t o mor e clearl yestablis h the difference s i n performanc e betwee n th e two . W e believ e thi s t o be the mos t rapi d wayo f resolving the question s surrounding you r hardware . Give n GM' s concern s abou t the performanc e o f simpl e design s suc h a s ours , yo u shoul d als o fin d suc h testing valuable . Othe r result s presente d i n you r briefin g indicate d tha t yo u encountere d liqui d carryove r fro mthe vapo r vent/rollove r valv e unde r variou s vehicl e maneuverin g tests . A s w e discussed , afte r you r modification s o f th e valve , yo u di d n o testing t o determin e ho wwel l the hand-modifie d floa t wa s abl e t o sea l th e ven t opening . Lackin g thi s information , i t i s impossibl e t o determin e whethe r the fue l carryove r i s a ch'aracteristi c o f you r particula r design , o r whethe r th e valv e wa s simpl yleaking . No r di d yo u evaluat e an ysolutions , whic h mayb e a s simpl e a s extending the lengt h o f the valv e barre l t o provid e fue l drainbac k capability . I n your presentation , yo u als o mad e th e statemen t tha t the EPAsystemcan generat e 2 0 time s mor e running los s vapor s tha n d o pressurize d tanks . Thi s statemen t i s misleading , implying a s i t doe s tha t the compariso n i s wit h the curren t stoc k versio n o f thi s system . I n fact , t o develo p thi s result , yo u modifie d th e stoc k vehicl e an d equippe d i t wit h a tan k pressur e contro l valv e whic h pressurize d the tan k an d suppresse d vapo r generatio n t o abou t l/10t h o f th e stoc k configuration . Compare d t o the stoc k car , th e EPAdesig n (assuming you r result s i n thi s cas e t o b e vali d fo r our design ) produce d abou t twic e the amoun t o f vapors . A s I note d above , ther e wer e a numbe r o f unanswere d question s resulting fro myou r briefin g on th e Genera l Motor s onboar d system . Thes e question s ar e include d a s a n attachmen t t o thi s letter . I woul d appreciat e you r promp t respons e t o thes e question s s o tha t w e can complet e our analysi s o f you r results . I als o believ e i t i s importan t t o respon d t o a matte r raise d i n you r recen t lette r o f Septembe r 15 , 198 8 respondingP. 5

t o m yreques t fo r a technica l briefing on you r onboar d hardwar e evaluation . I n you r lette r yo u raise d the concer n tha t m yus e o f th e word "critique " implie d tha t w e wer e approaching our analysi s wit h " a predispositio n t o eithe r discredi t o r ignor e Genera l Motor s dat a regardles s o f it s merit. " Thi s concer n i s disturbing , give n tha t I hav e repeatedl yemphasize d t o yo u i n previou s phon e conversation s tha t our interes t i n a technica l briefing wa s premise d o n th e fac t tha t EPAha s a n obligatio n t o objectivel yevaluat e an yinformatio n o r dat a tha t relate s t o our deliberations . I t i s fo r thi s reaso n alon e tha t I requeste d a detaile d technica l briefing fro mGM . I assur e yo u tha t your concern s ar e unfounde d an d tha t w e wil l certainl y evaluat e you r dat a o n thei r merit . W e hav e mad e simila r briefin g request s t o othe r manufacturer s an d theyhav e responde d favorably . Than k yo u onc e agai n fo r your presentation . I loo k forwar d t o hearing fro m yo u abou t the loan o f your equipmen t fo r testing an

d receiving you r respons e t o our remaining questions . Sincerel yyours ,
Cheste r J . France , Chie f Standard s Developmen t an d Suppor t Branc h Enclosur e ac: Richar d Wilson , EPA Charle s Gray , EP

A Samue l Leonard , G

M Docke t A-85-2 1 Docke t A-87-1 1 6394 WP. 6

; . •,..•:>'

• v ' • • » Followu p Question s t o Genera l Motors ' Onboar d Hardwar e Briefing Partia l fil l tes t procedur e Ho wwa s nomina l capacit ydefine d an d wha t wa s it s valu e Provid e dat a o n gram s emitte d pe r tes t rathe r than gram s pe r gallo n Describ e topping of f procedur e including numbe r o f shutoffs , etc . Identif ytest s wher e spitbac k occurred , an d whe n i n the tes t i t happene d Identif yfil l rate s fo r al l test s Vehicl e maneuverin g test s Identif yspecifi c test s performe d Provid e detail s o f the geometryo f th e installe d onboar d systemshowing al l lin e grade s an d length s fro mthe contro l valv e t o th e caniste r Provid e th

e same detail s o n the liqui d los s tes t configuration . Estimat e the volume o f liqui d los t a s wel l a s it s weigh t Provid e an

ydat a yo u hav e evaluating the basi c performanc e o f the floa t an d sea l mechanis mi n th e modifie d valve . Ho t driving unde r load Provid e dat a o n ambien t temperature s fo r al l test s Describ e the roa

d rout e i n detai l including averag e driving speed s Describ e vehicl e preparatio n prio r t o tes t including an ydriving Indicat e whic h portion s o f th e roa d rout e wer e drive n fo r eac h tes t an d exac t mileag e an d time s Base d upo n pas t G M experienc e wit h thes e route s or portion s o f routes , describ e th e expecte d effect s o n fue l tan

k temperatur e ris e abov e ambien t Describ e the sampl e collectio n equipment , including al l component s an

d physica l layou t Identif ytan

k operating pressur e wit h the tan k pressur e contro l valv e installe d Howdoe s thi s systemcontro l fue l spurting i f th e fue l ca p i s remove d fro

ma fue l tan

k whe n hot ? Identif ytypica l tan k operating pressure s unde r simila r ambien t condition s fo r the tan k withou t the tan k pressur e contro l valv e Fil l Qualit y Describ e specifi c fil l qualit ytest s performe d Provid e quantitativ e result s Provid e simila r dat a fo r the stoc k fue l tan k