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# OAR Box 1830 Prepped by Ollie Stewart



### Document

Number: 

# 184 ) IV-C-15 1 Docket Number: 

# A-87-1 1

Printed 11/13/20087:21:01 AM Sheet 184 of 232g

_ \ \ UNITE D STATE S ENVIRONMENTA L PROTECTIO N AGENC Y \^StZJ

AN N ARBOR

. MICHIGA N 48105 

## N«^ / OFFIC E O F AI R AN D RADIATIO N JA N ! 7 I98 Q

Mr . Jame s E . Pase k ^T J Manager , Federa l Activitie s . > ^ r>c\' ^ Genera l Motor s Corporatio n ^. v0 , y;-y :
. ^ Genera l Motor s Technica l Cente r ^'"" c-"' ' 3040 0 Moun

d Road Warren , Michiga n 48090-901 5 Dea r Mr . Pasek : I n you r communicatio n o f Decembe r 8 , 198 8 t o Joh n Anderso n regarding the Octobe r 24 , 198 8 memorandu mfro mmysel f thr u J . Anderso n t o Docke t A-87-11 ) you- 5 commente d o n severa l issue s relate d t o EP

Atesting o f two vehicle s equippe d b yExxo n wit h onboar d refueling vapo r recover ysystems . Th e purpos e o f thi s lette r i s t o respon d t o your comments , an d t o provid e additiona l informatio n abou t th e test s tha t wer e performe d an d the . result s obtaine d fro mthem . Th e firs t o f you r concern s relate d t o caniste r preconditionin g prio r t o the firs t tes t o f eac h vehicl e an d betwee n subsequen t tes t sequences . I n particular , yo u note d tha t no informatio n wa s provide d abou t caniste r preconditionin g befor e th

e star t o f testing on eac h vehicle , an d tha t a

n "arbitrary " driving schedul e wa s applie d t o eac h vehicl e betwee n tes t sequences . A s yo u noted , th e draf t Federa l Tes t Procedur e fo r vehicle s equippe d wit h onboar d refueling vapo r recoverysystem s doe s no t contai n an yprovisio n fo r caniste r preconditionin g prio r t o the star t o f the propose d tes t procedure . I n fact , th e tes t procedur e itsel f i s specificall y designe d t o conditio n the onboar d caniste r t o a know n an d repeatabl e loading , regardles s o f prio r caniste r history . Therefore , provisio n fo r a caniste r preconditionin g procedur e i n additio n t o tha t containe d i n the propose d tes t procedur e i s specificall yomitted . I t shoul d be note d tha t th e existing Federa l Tes t Procedur e applicabl e t o vehicle s equippe d wit h curren t evaporativ e emission s contro l system s als o omit s the typ e o f caniste r preconditionin g step tha t yo u fin d lackin

g in the propose d tes t sequence , ye t the curren t procedure s hav e bee n prove n t o be bot h consisten t an d repeatable .P. 3

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- Although no t explicitl yprovide d fo r in the propose d tes t procedures , testing o f th e vehicle s di d includ e a n on-road driv e betwee n eac h o f th e tes t sequence s tha t wer e carrie d out . Th e purpos e o f thes e drive s wa s t o qualitativel yevaluat e driveabilit yo f th e vehicle s unde r condition s o f a fully-loade d refueling canister , a s wel l a s t o provid e some purg e t o ensur e tha t th

e refueling caniste r wa s no t loade d beyon d it s breakthrough poin t a t the star t o f the nex t tes t sequence . I t i s th e inten t o f EP

Atha t vehicle s equippe d wit h integrate d onboar d vapo r recover ysystem s b

e capabl e o f passing th e propose d tes t procedur e regardles s o f th e caniste r loading or historya t the star t o f the test . Thi s inten t i s reflecte d in th e tes t procedure , whic h provide s fo r a quantit yo f hydrocarbon s t o be adde d t o the caniste r during preconditionin g tha t ma yvar ydepending on th

e initia l caniste r load . Th e on-road drive s performe d betwee n tes t sequence s wer e non-specifi c in . th e sens e o f no t conformin g t o a rigi d time/spee d schedule , bu t al l drive s wer e highl ysimila r in nature . Eac h driv e consiste d o f a cor e rout e consistin g o f mostl yrura l an

d highwa

yroads . Poste d spee d limit s wer e followed , s o tha t th e driving schedul e ove r the rout e wa s consisten t fro

m tes t t o test . In some cases , thi s cor e rout e wa s supplemente d b yadditiona l highwa yan d cit ydriving t o furthe r evaluat e driveabilit yunde r differen t conditions . I d o no t believ e tha t the natur e o f thes e drive s contribute d in an y wa yt o tes t result s being inconsisten t or unrepeatable . Anothe r concer n raise d in yo u lette r wa s tha t EPAmeasure d emission s wer e highe r than the baselin e o r stoc k vehicl e emission s reporte d b yExxon , an

d tha t thi s indicate d tha t seriou s concer n shoul d b e give n t o purge/exhaus t interactions . Th e dat a als o show , however , tha t emission s fro mthe onboard vehicle s measure d b yEP Aar e highe r than thos e measure d b y Exxo n unde r th

e same conditions , indicating a systemati c offse t betwee n result s obtaine d fro mthe two laboratories . Eve n befor e accounting for thi s offset , emission s fro mth e onboard-equippe d vehicles , a s measure d b yEPA , ar e no t significantl yhighe r than thos e fro mthe stoc k vehicle , a s measure d b

yExxon . Whe n the apparen t laboratoryoffse t i s considered , the conclusio n tha t th e dat a showcaus e fo r seriou s concer n abou t caniste r purge/exhaus t emission s interaction s i s eve n les s credible . I t shoul d be note d tha t in al l cases , eve n the apparentl y"higher " emission s measure d b yEP Aar e withi n curren t standards , indicating tha t an yinteraction s tha t do exis t ar e smal l enough t o avoi d seriou s concern . As state d in th

e text , th

e refueling emission s system s designe d an

d fabricate d b

yExxo n di d no t provid e sufficien t purg e t o pas s th

e refueling test . Th e ver yfac t tha t th

e stoc k evaporativ e contro l systemdoe s provid e nearl yal l o f theP. 4

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- require d purg e volume , however , indicate s tha t "extensiv e developmen t work " i s no t neede d t o upgrad e performanc e o f critica l purg e system component s t o th e require d level . Evaluatio n o f th

e Exxon-designe d onboar d vapo r recover ysystem reveale d severa l design flaws , s o tha t tes t failure s can b e attribute d t o deficiencie s i n implementatio n o f th e system , rathe r than t o an yintrinsi c deficienc yi n the simplifie d refueling emission s contro l systemdesign . EPAcanno t agre e wit h you r conclusio n tha t extensiv e developmen t wor k i s neede d t o achiev e th

e desire d leve l o f performance . Finding s o f th e EP Aevaluatio n o f th e Exxo n refueling emission s contro l systemals o reveale d deficiencie s tha t relat e t o problem s encountere d wit h liqui d sea l establishmen t an d wit h fil l quality . I n particular , EPAfoun d tha t the Exxo n systems : 1 ) di d no t includ e prope r placemen t o f th e fil l pip e outle t insid e the fue l tank ; 2 ) di d no t us e th e correc t vent/rollove r valve ; 3 ) di d no t provid e acceptabl e qualit ycheck s on modification s mad e t o the . vent/rollove r valve s supplie d wit h the vehicle . Eac h o f thes e component s ar e essentia l t o prope r functioning o f a n integrate d onboar d refueling emission s contro l system . I t canno t be logicall yconclude d tha t failure s o f system s tha t do no t confor mt o design s know n b yEPAt o perfor mproperl yindicat e tha t th e liqui d sea l systemitsel f i s no t capabl e o f effectivel ycontrollin g refueling emissions . Finally , I acknowledg e tha t during productio n testing o f onboard-equippe d vehicles , refueling canister s woul d i n fac t remai n i n thei r intende d position . Th e experimenta l natur e o f the test s performe d on th e Buic k vehicle , however , dictate d tha t the caniste r no t remaining it s "normal " positio n s o tha t caniste r weight s coul d b e obtaine d t o ai d in understandin g th e influenc e o f th e tes t procedur e o n systemperformance . I d o no t believe , no r d o experimenta l dat a show , tha t placemen t o f the refueling caniste r o f the Buic k vehicl e significantl yo r adversel yaffecte d performanc e o f th e vehicl e or th

e tes t result s obtaine d fro mit . Severa l additiona l concern s wer e expresse d in your communication , including the fac t tha t the test s di d no t conside r th e effect s o f high temperature s an d fue l volatilities , running losses , o r high fue l deliveryrates . Th e test s performe d on th e tw o Exxo n vehicle s wer e intende d primaril yt o evaluat e the propose d Federa l Tes t Procedure s a s applicabl e t o vehicle s equippe d wit h onboar d refueling emission s contro l systems , an d t o provid e a n initia l evaluatio n o f th e Exxon-designe d systems . Evaluatio n o f th e effect s mentione d abov e ar e clearl ybeyon d the scop e o f the test s performe d on th

e Exxo n vehicles .P. 5

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Than k yo u fo r you r comment s o n result s obtaine d fro mthi s tes t program . I hop e tha t th e item s discusse d abov e wil l clarif yth e procedure s an d result s associate d wit h thes e tests , an d b e o f assistanc e t o yo u i n interpretin g th e significanc e o f th e tes t results . Sincerel y

Dr . Davi d B . Bartus , Chemica l Enginee r Standard s Developmen t and Suppor t Branc h

cc : D^pCffce

t A^87:-ll ?