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Number: 

# 67 ) II--A0 4 Docket Number: 

# A-87-1 1

Printed 11/24/200812:41:50PM Sheet 67 of 82 P. 1P. 2 

# ^ " I ~1 f\4n\ a-ft-off

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* . . * • EPA-AA-SDSB-85-5c \ Technica l Repor t

Draf t Recommende d Tes t Procedur e fo r th e Measuremen t o f Refuelin g Emission s

By Lis a D . Snapp Jul y198 5

NOTIC E Technica l Report s d o no t necessaril yrepresen t fina l EPA decision s o r positions . The yar e intende d t o presen t technica l analysi s o f issue s using dat a whic har e currentl yavailable . Th e purpos e i n th e releas e o f suc h report s i s t o facilitat e th e exchang e o f technica l informatio n an

d t o infor

mth e publi c o f technica l development s whic hmayfor mth e basi s fo r a fina l EPA decision , positio n o r regulatoryaction . Standard s Developmen t an d Suppor t Branc h Emissio n Contro l TechnologyDivisio n Offic e o f Mobil e Source s Offic e o f Ai r an

d Radiatio n U . S . Environmenta l Protectio n Agenc yP. 3

Tabl e o f Content s
I . Introductio n 1 II . Historyo f th e Procedur e . 1 

### III . Recommende dProcedur e 3 A . Equipmen t 3 B . Procedur e 4 C . Parameter s 7 1 . Tes t Fue l Volatilit y1 2 2 . Dispense d Fue l Temperatur e 1 6 3 . Temperatur e Differentia l 2 0 4 . Fue l Leve l Prio r t o Refueling 2 4 5 . Fue l Dispensin g Rat e 2 5 D . Vehicl e Preconditioning 2 8 E . Caniste r Purging an d Vehicl e Drivedown 3 0 F . Testin g Requirement s fo r In-Us e Vehicle s ... . 3 3 1 . Preconditioning Problem s 3 3 2 . Testin g Problem s 3 6P. 4

I . INTRODUCTIO

N Th e emission s whic hoccu r a s a resul t o f vapor s displace d durin g th e refueling o f moto r vehicle s ar e currentl yo f publi c an d Agenc yconcern . Thes e vapor s hav e possibl e advers e healt h effects , a s doe s benzene , a substanc e i n gasolin e vapor s linke d t o cancerou s an

d mutageni c effects . The yals o contribut e t o th e formatio n o f photochemica l smog , whic hi s o f grea t concer n i n area s whic hexcee d th e Nationa l Ambien t Ai r Qualit yStandar d (NAAQS ) fo r ozone . Becaus e o f thes e concerns , EP Aha s undertake n a detaile d evaluatio n o f variou s regulatory strategie s whic hcoul d b e use d t o reduc e emission s du e t o refueling.[1 ] On e aspec t o f thi s evaluatio n involve s th e measuremen t o f refueling emission s frombot hcurren t vehicle s an d vehicle s equippe d wit hprototyp e refueling vapo r contro l systems . EPAha s bee n involve d i n th e developmen t o f a tes t procedur e designe d t o measur e thes e emission s fo r quit e some time . EPAbega n workin g wit htes t procedur e issue s durin g th e summe r o f 1984 . Aworksho p wa s hel d o n Octobe r 17 , 198 4 a t whic hEP Ashare d it s idea s o n th e tes t procedur e and o n critica l tes t parameter s wit hworksho p participants . Thos e presen t a t th e worksho p wer e urge d t o submi t comment s o n th e draf t recommende d practic e an d some o f them

di d so . A follow-u

p meetin g wa s hel d o n February15 , 198 5 a t whic h industryrepresentative s furthe r detaile d thei r thought s abou t th e draf t tes t procedur e a s propose d b yEPA . EP Aha s considere d th e comment s submitte d i n respons e t o th e initiall ypropose d tes t procedur e i n developmen t o f thi s curren t versio n o f th e recommende d practice . Thi s repor t summarize s th e developmen t o f th e recommende d tes t procedur e including discussion s o f equipmen t neede d an d value s fo r critica l tes t procedur e parameters . II . HISTORY O F TH E PROCEDUR E I n 1973 , th e Societ yo f Automotiv e Engineer s (SAE ) approve d Recommende d Practic e J1045 , "Instrumentatio n an d Technique s fo r Vehicl e Refueling Emission s Measurement, " whic h wa s designe d t o measur e refueling emission s fromuncontrolle d vehicles.[2 ] Th e procedur e wa s designe d mostl yfo r experimenta l purposes , i n tha t i t wa s t o b e use d t o determin e th e effect s o f variou s parameters , suc ha s temperatures , fue l volatility , an

d s o forth , o n refueling emissions . Wit hthes e parameter s hel d constant , i t coul d als o b e use d t o measur e th e contro l efficienc yo f refueling emissio n contro l devices .P. 5

-2

- Th e SAE procedur e incorporate d four ke yparameter s fo r us e whe n measurin g refueling emissions . Thes e wer e th e fue l volatility , fue l tank temperature , dispense d fue l temperature , an d fue l leve l prio r t o refill . Als o specifie d wa s th e testin g equipmen t t o b e used , mos t notabl yth e seale d housin g fo r evaporativ e determinatio n (SHED) , an d procedure s fo r conducting th e tests . I n th e SAE recommende d practice , th e tes t fue l specifie d ha d a volatilit yo f 9.0+0. 5 ps i a s measure d byRei d Vapo r Pressur e (RVP) , whic hi s comparabl e t o normall yspecifie d value s i n Federa l tes t procedure s an d SAE recommende d practice s fo r evaporativ e an d tailpip e emission s testing . Fue l tank temperatur e wa s recommende d t o b e 95+2°F , whic hSAE foun d t o b e a reasonabl e temperatur e t o expec t i n summe r drivin g conditions ; n o supporting dat a wa s cited . Dispense d temperatur e wa s 82+1°F , a n averag e summe r dispense d temperatur e reporte d byScot t Researc hLaboratories.[3 ] Fue l leve l prio r t o refil l wa s suggeste d a t one-fourt htank capacity ; again , n o dat a wa s cite d i n suppor t o f thi s value . Th e equipmen t t o b e used , particularl yth e SHED , wa s als o prescribe d b

yth e SAE procedure . I t wa s specifie d t o b e th e same a s th e SHE D generall yuse d fo r evaporativ e emission s testing , wit hmino r alteration s suc ha s a n adde d fue l dispensing hos e an d nozzle . Als o specifie d i n some detai l wer e th e equipmen t component s necessaryfo r heatin g th e fue l tank , analyzing th e H C emissions , mixin g an d purging th e air , an d recording temperatures . Procedure s fo r using th e equipmen t wer e given , along wit h tolerance s o f applicabl e parameters . Th e basi c tes t procedur e involve d drainin g th e fue l tank t o nominall yempty , filling i t t o one-fourt ho f tank capacity , an d pushing th e vehicl e int o th e SHED . Fue l tank temperatur e wa s the n t o b e raise d t o th e specifie d tes t temperatur e b ymean s o f an electri c heatin g pa d applie d beneat hth e tank , generall yreferre d t o a s singl e blanke t heating . Whe n th e desire d temperatur e wa s reached , th e SHE D wa s t o b e close d and , upo n stabilizatio n o f background hydrocarbo n concentration , th e operato r wa s t o ente r th e SHE D an d refue l th e vehicle , allowing th e nozzl e t o automaticall y shu t of f whe n th e tank wa s full . Reading s o f hydrocarbo n concentration , elapse d time , ambien t temperature , an d barometri c pressur e wer e t o b e taken , an d th e mas s o f emission s du e t o th e refueling coul d the n b e calculated . Th e SAE procedur e describe d abov e an d th e Federa l tes t procedur e fo r evaporativ e emission s wer e use d t o develo p th eP. 6

-3

- EP Arecommende d tes t procedur e fo r refueling emission s outline d below . Thi s procedur e use s th e basi c SHE D tes t approac hfo r measurin g H C refueling emissions , an d integrate s i t int o th e existin g federa l tes t procedur e (FTP ) fo r exhaus t an d evaporativ e emissions . Th e remaining section s o f thi s repor t discus s thi s procedur e an

d ar e organize d a s follows . First , th e equipmen t t o b e use d t o performth e testin g wil l b e describe d i n Sectio n III.A . Thi s wil l b e followe d i n Sectio n III.B . bya revie wo f th e tes t procedur e sequenc e itself . Section s III.C.1- 5 wil l dea l wit hth e derivatio n o f specifi c tes t conditions , including tes t fue l volatility , dispense d fue l temperature , temperatur e differential , fue l leve l prio r t o refueling , an d fue l dispensing rate . Vehicl e preconditioning i s discusse d i n Sectio n III.D , followe d b ya mor e detaile d discussio n o f th e caniste r purging an d vehicl e drivedow n portio n o f th e tes t sequenc e i n Sectio n III.E . Finally , th e applicatio n o f thi s tes t procedur e t o in-us e vehicle s i s describe d i n Sectio n III.F . III . RECOMMENDE D PROCEDUR E A . Equipmen t Th e equipmen t t o b e use d i n th e EPArefueling tes t i s simila r t o tha t recommende d bySAE an d tha t specifie d i n th e evaporativ e emission s portio n o f th e Federa l tes t procedure . Thi s equipmen t consist s o f a SHED , fue l dispenser , meters , an d recording devices . Th e SHE D itsel f i s essentiall yth e same , excep t tha t th e *|ue l lin e opening i n th e SHE D wal l mus t b e lowe r tha n th e fue l tank opening o n th e vehicle , t o eliminat e th e potentia l fo r siphonag e an d spillag e ont o th e floor . Othe r piece s o f equipmen t - th e flame ionizatio n detecto r (FID ) hydrocarbo n analyzer , purg e an d mixin g blowers , thermocouple s an d recording device s - ar e als o essentiall yth e same i n th e EP Ates t procedur e a s i n th e SAE procedure . Th e fue l dispensin g system

varie s i n tha t th e EPAprocedur e require s a self-supporting nozzl e an d a fue l flo wshut-of f switc ho n th e fue l cart . Thi s eliminate s th e nee d fo r a nozzl e operato r insid e th e SHE D whe n vapor s ar e accumulating . Anothe r differenc e i s i n th e fue l tank heatin g systemuse d durin g preconditioning . Th e SAE procedur e prescribe s a maximu m liquid-vapo r temperatur e differentia l o f 6F° , whic hlimit s th e spee d o f liqui d heating , whil e th e EP Aprpcedur e allow s heating a s quickl ya s possible , wit hth e temperature s the n hel d i n equilibriu

mfo r te n minute s afte r completio n o f heating . Thi s equipmen t i s use d t o conduc t th e refueling test , whic hi s integrate d int o th e FT P a s describe d i n th e following section .P. 7

-4 - B . Procedur e The proposedtes t sequenc e fo r exhaust , evaporative , an d refuelin

g emission s use s th e current sequenc e fo r exhaus t an

d evaporativ

e emission s an

dadd s refuelin

g test s a

t th e beginnin

g an dend . Thes e tw o ne w test s are designedt o checkthe capacity

an dpurge capability of th e refuelin

g contro l syste

m separately . Thei r integratio ninto th

e FT P i s show

ni nFigur e 1 an ddescribedbelow . The tes t begin s witha refuelin g tes t performedt o ensur e that th

e overal l vapor contro l capacity of the canister i s sufficient fo

r a complet e fill-up . Certificatio ntes t vehicle s are expectedt o arriv e a t the tes t sit e purgedt o a leve l commensurat e witha nearl y empt y fue l level . Prior t o testing , the fue l tan

kwil l be drainedan dfille

dt o 1 0 percent o f capacity

wit hstandar

dtes t fuel . The refuelin g caniste r wil l be disconnecteddurin g thi s operation . In-us e vehicle s ma y arriv e i nan y condition , an

dwil l b

e preconditionedb y 5 0 mile s of drivin

g o nstandar

dtes t fue l usin

g th e durability

drivin

g schedul e containedi nAppendi xI

V of Par t 8 6 of th e Code of Federa l Regulation s (CFR) , o r equivalent urbandriving . Followin

g th e 5 0 mile s of driving , the fue l tan kwil l agai nb e draine dan dfuele

dt o 1 0 percent of capacity . A s wit h certificatio

nvehicles , the refuelin g canister wil l be disconnectedfo

r thi s step . To prevent an y canister loadin

g whil e an

y vehicl e await s testin g a t th e facility , the ga s cap wil l b e loosene

do r remove

dwhenth

e vehicl e i s no t in operation . Immediatel y

prior t o testing , the vehicl e wil l be pushed into : th

e SHEDan

dth e door s an

dluggage compartment s wil l be opened . The fue l i nth e vehicl e fue l tan kwil l thenundergo a hea t buil dto the prescribedtes t temperature , followe db y a te nminut e equilibriu m period . The fue l dispensin g nozzl e wil l be placedinthe vehicl e fil l neck , an dth e SHEDclose

dan d sealed . A

switchoutside of th e SHEDwil l thenbe usedto start the flo

w of fuel . Gasoline shal l be dispensedinto the fue l tan

kunti l th

e automati c shutof f feature o nth e fue l nozzl e i s tripped . A t the tim

e tha t fue l flo

w i s terminated , the fue l tan

kmus t b e fille

dt o a t leas t 9 5 percent o f nomina l tan kcapjacjity . The tota l vehicl e refuelin g emission s wil l be definedam

the hydrocarbonleve l i nth e SHED(as measuredb y FID ) a t the tim

e of terminatio

nof th e fuelin

g event . For baseline testin g of vehicle s equippedwithcurrent technology , som

e difficultie s withspillage a t nozzl e shutof f ma y occur . I

norder to avoi dexcessiv e emission s an

dhig hP. 8

Figur e1 § M.130-7 S TrH o 40—Protectio n o

fEnvironmont

DIURNA l MA TIUH 0

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T NO TRt Q OIURNA l

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TEXHAUS

TTES T Refueling Capacit yTes t

- 85 % fil l tes t

- caniste r saturatio n

I HOU R MA X

J MIN . MAX .

_Disconnec t

Caniste r Reconnec t

> < ? 3 6 HOURS (n o max . lo r

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T NO T PERFORME D HC RUNNIN G

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# 3Z > MI N

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CN D Refuelin g Purg eTes t

- IA- 4 drivedow

n

- 30 % fil l tes t

PlfW t l/ l 1 0 TtI TSIOUINC IP. 9

-6

- test-to-tes t variabilit ycause d b yspillage , manua l nozzl e shutof f a t th e 9 5 percen t ful l leve l i s sometime s necessaryi n thi s case . Fo r ne wvehicle s equippe d wit honboar d controls , however-^jEueling system s shoul d b e designe d suc htha t n o spillage^wil l occu r whe n a properl yfunctioning nozzl e i s use d t o fue l thfr vehicle . Anyemission s cause d b yspillag e woul d b e include d a s par t o f th e vehicle' s tota l refueling emissions . Next , th e vehicl e fue l tank wil l b e draine d an d refille d repeatedl yunti l th e caniste r i s saturate d an d hydrocarbo n breakthroughoccurs . "Breakthrough " wil l b e define d a s tha t poin t i n tim e tha t th e concentratio n indicate d byth e FI D hydrocarbo n trac e increase s bya facto r o f a t leas t 3 i n a on e minut e period . A t thi s point , th e vehicl e wil l begi n th e existin g tes t sequenc e fo r exhaus t an d evaporativ e emissions . Currently , th e tes t procedur e specifie s a fue l drai n an d fil l a t thi s point . I n th e refueling tes t procedur e th e vehicl e manufacture r wil l hav e th e optio n t o adjus t th e fue l leve l i n th e tank t o th e specifie d leve l o f 4 0 percen t following caniste r saturation , o r performth e existing drai n an d 4 0 percen t fil l operation . I n eithe r cas e th e refueling caniste r wil l b e disconnected . Th e nex t step s i n th e procedur e follo wth e existing FTP . First , a singl e dynamomete r preconditioning cycl e i s done , followe d bya col d soak fo r betwee n 1 0 an d 3 5 hours . Additiona l preconditioning , allowe d unde r th e curren t FTP , wil l n o longe r b e permitted . Afte r th e soak , th e FT P call s fo r th e fue l tank t o b e draine d an d fille d t o 4 0 percen t o f tank capacity . Fo r th e refueling procedure , th e caniste r wil l b e disconnecte d befor e thi s fue l drai n an d fil l i n orde r t o avoi d additiona l caniste r loading. * Th e caniste r wil l the n b e reconnecte d an

d th e FT P wil l continu e a s usual , wit hth e diurna l breathin g los s SHE D test , col d an d ho t star t dynamomete r exhaus t tests , an d ho t soak evaporativ e SHE D test . Thi s aspec t o f th e procedur e i s stil l subjec t t o change . Leavin g th e caniste r connecte d woul d requir e substantiall y increase d purg e capacit yduring th e dynamomete r preconditionin g cycl e an d migh t b e unnecessaril ysevere . O n th e othe r hand , i t mayhappe n tha t a purg e strategy capabl e o f adequatel ypurging al l th e collecte d refueling vapor s during norma l driving woul d hav e a purg e capabilit y a t saturate d caniste r condition s whic happroximate s thi s highe r rate . Thi s subjec t i s discusse d furthe r belo wi n connectio n wit hth e drivedow n portio n o f th e test .P.1 0

-7

- The&f-inal.. . stag e i n th e refueling tes t procedur e i s a purg e tes t sequenc e involving dynamomete r operatio n o f th e vehicl e t o drive * dovnif approximatel y3 0 percen t o f th e fue l i n th e tank , followedl~b5g j a partia l refueling operatio n t o replac e th e consumed ? fuel . Th e purpos e o f thi s stag e i s t o demonstrat e tha t th e refueling contro l systemha s adequat e purg e capacit y t o purg e accumulate d refueling vapors . Fo r reason s t o b e discusse d furthe r below , th e drivedow n sequenc e i n thi s draf t recommende d practic e i s initiall ybeing applie d onl yt o vehicle s employing refueling emission s contro l system s whic h ar e completel yseparat e froman yevaporativ e emission s controls . Vehicle s havin g refueling emission s contro l integrate d wit heithe r th e diurna l fue l tank emission s contro l o r al l evaporativ e emission s control s ar e no t bein g require d t o underg o th e drivedow n portio n o f th e tes t a t thi s time . However , i t i s no t ye t clea r t o EP Atha t th e refueling procedur e lacking th e drivedow n is , i n fact , completel y adequat e fo r testing integrate d refueling an d evaporativ e contro l systems . I n fact , ther e ar e indication s tha t a 3 0 percen t drivedown operatio n mayitsel f b e inadequat e t o verif y prope r caniste r purg e fo r a ful l refueling . Thes e uncertaintie s ar e discusse d furthe r belo wi n Sectio n E , Caniste r Purging an d Vehicl e Drivedown . Th e purg e tes t wil l begi n wit ha drivedow n sequenc e o n th e dynamometer , consisting o f sequentia l Urba n Dynamomete r Drivin g Schedules , containe d i n Appendi xI o f Par t 8 6 o f th e CF R an d normall yreferre d t o a s th e LA-4 , alternating wit hon e hou r ho t soaks . Thi s sequenc e i s intende d t o us e fue l an d allo w refueling caniste r purge , i n orde r t o subsequentl yperforma partia l refueling wit han amoun t o f fue l larg e enought o adequatel ytes t th e system' s purg e capability . Th e LA-4/ho t soak sequenc e wil l b e repeate d unti l approximatel y3 0 percen t o f th e tank fue l capacit yha s bee n used . Th e vehicl e wil l the n b e pu t bac k int o th e SHED , an d a refueling tes t conducte d a s a t th e beginning o f th e propose d procedure , excep t tha t th e refueling amoun t shal l approximatel ycorrespond t o th e amoun t o f drivedown . C . Parameter s I n th e draf t procedure , fiv e ke ytes t parameter s affecting refueling emission s wer e identified : tes t fue l volatility , dispense d fue l temperature , differentia l betwee n dispense d fue l temperatur e an

d vehicl e liqui d fue l tank temperature , initia l an d fina l fue l tank volumes , an d fue l dispensin g rate . Th e value s fo r thes e tes t parameter s hav e bee n chose n s o tha t roughl y9 0 percen t o f th e refueling event s unde r ozone-pron eP.1 1

-8

- summe r condition s woul d b e covered. * Tes t paramete r value s ar e show n i n Tabl e 1 . I n orde r t o choos e th e appropriat e values , i t wa s necessaryt o kno wtypica l level s o r hav e frequenc y distribution s o f th e level s o f th e ke yparameter s during th e month s an

d i n th e region s o f interest . Informatio n use d t o selec t th e appropriat e value s fo r th e ke yparameter s wa s take n fromsevera l sources . Thes e source s ar e briefl ydescribe d belo wan

d summarize d i n Tabl e 2 . On e importan t stud ywa s conducte d byth e America n Petroleu

mInstitut e (API ) Produc t Temperatur e Tas k Forc e i n 1975 . I n thi s survey , gasolin e temperatur e dat a wa s collecte d a t 5 6 servic e station s throughou t th e Unite d States.[4,5 ] Th e dat a analysi s repor t b yRadia n Corporatio n unde r contrac t t o API , an

d th e fina l AP I repor t generate d from thi s data , provide d informatio n whic hEPAuse d t o establis hfrequenc y distribution s o f dispense d fue l temperatur e an d temperatur e differentia l fo r th e country , divide d int o si xregion s a s show n i n Figur e 2 . Distribution s o f th e fue l leve l i n a vehicl e befor e i t i s take n i n fo r a fill-u p wer e derive d from si xstudie s don e a s par t o f California' s servic e statio n Stag e I I vapo r contro l program.[6,7,8,9,10,11 ] Thes e studie s recorde d amoun t o f gasolin e dispense d pe r refueling a t a variet yo f servic e stations . Typica l flowrate s use d i n dispensin g suc hfue l wer e provide d t o EPAb ya n informa l AP I surve yo f membe r companies.[12 ] Maximu mfue l volatilit yprescribe d i n th e summe r month s o f th e appropriat e region s wa s take n fro mth e America n Societ yfo r Testing an

d Material s (ASTM ) standards.[13 ] Th e effect s o f weathering o n volatilit ywer e studie d i n th e EPAbaselin e refueling testing programan d i n a n AP I stud yconducte d b

y Stanfor d Researc hInstitut e t o develo p a tes t procedur e fo r servic e statio n vapo r contro l systems.[14 ] Th e value s whic h thes e source s provide d fo r th e ke ytes t parameter s ar e discusse d i n th e following sections . Sinc e refueling emission s contro l i s als o importan t fo r reason s othe r tha n ozon e reductions , th e tes t parameter s mus t als o ensur e adequat e contro l requirement s fo r non-summe r conditions . Base d o n th e refueling emissio n factor s develope d i n EPA' s baselin e study[16] , th e choic e o f summertime conditio n wil l ensur e year-round control .P.1 2

Designatio

n Volatility , RV P Tabl e 1

Critica l Tes t Parameter s

Meanin g

dispensedtemperature , T D temperatur e differential , A T fue l leve l

dispensin

g rat e tes t fue l volatility , expresse

di nRei d Vapor Pressure temperature of dispense

dfue l tan ktemperature minu s dispense

dtemperatur e leve l of fue l invehicl e prior t o refueling , percent of capacity t o neares t 0. 1 U.S . ga l flo w rat e of fue l a s i t i s dispensed Value 11. 5 + 0. 5 ps i

8 8 + 2° F

+ 2 t o + 5 F

« 

### 10 %

8-1 0 gal/mi nme i P.1 3

Yea r Conducte d 197 5

198 4

197 4

198 4

197 6

197 6

197 9

198 2

197 6

198 1

198 4 Tabl e 2 Source s fo r Paramete r Value s Sourc e Radian/API[4,5 ]

ASTM[13 ]

Stanford[14 ]

SWRIC17 ]

Unio n 76[6 ]

Unio n 76[7 ]

Unio n 76[8 ]

HealyC9 ]

Exxon[10 ]

Emc o Wheaton[ll ]

AP I Letter[12 ] Paramete r TD , A T

RV P

RV P

RV P

fue l leve l

fue l leve l

fue l leve l

fue l leve l

fue l leve l

fue l leve l

dispensing rat e Comment s

Measure d underground , dispensed , and tan k fue l and ambien t temperature s Prescribe d fue l volatilit yclasse s by stat e and mont h Studie d effec t o f variables , including tan k fue l RVP (weathering ) o n refueling emission s Studie d amoun t o f fue l weathering experience d b yin-us e vehicle s Gav e fil l fractio n fo r 10 5 refuelings , fill-up s onl y Gav e gallon s o f fue l dispense d fo r 11 7 refuelings , fill-up s onl y Gav e gallon s o f fue l dispense d fo r 10 3 refuelings , wit h8 9 fill-up s Gav e gallon s o f fue l dispense d fo r 9 9 refuelings , wit h1 8 fill-up s Gav e gallon s o f fue l dispense d fo r 57 3 refue l ings , wit h32 7 fill-up s Gav e gallon s o f fue l dispense d fo r 9 9 refuelings , wit h4 0 fill-up s Surveye d AP I membe r companie s informall y fo r typica l fue l flow rate sP.1 4

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### .2P.1 5 mi

-12

- 1 . Tes t Fue l Volatilit y Fue l volatilit yha s a significan t impac t o n th e leve l o f refueling emissions , an d a s suc hi s on e o f th e critica l parameter s t o b e specifie d i n thi s tes t procedure . Commercia l fuel s wit hvolatilitie s tha t ar e highe r tha n tha t o f EPA certificatio n fuel s ar e currentl ysol d i n area s an d month s tha t ar e ozone-prone . Ozone-pron e state s currentl yinclud e an y stat e wit ha Standar d Metropolita n Statistica l Are a (SMSA ) whic hha d a violatio n o f th e NAAQ S fo r ozon e i n 198 2 o r 1983.[15 ] Th e month s o f violatio n ar e mainl yMa ythrough September , an

d th e state s ar e predominatel yi n th e Midwest , Northeast , Southeas t an d Southwes t area s o f th e Unite d States , a s ca n b e see n i n Figur e 3 . Th e 3 0 ozone-pron e state s fal l predominantl ywithi n four o f th e si xregion s whic hRadia n ha d designate d i n it s stud yo f gasolin e temperature[4] , als o show n i n Figur e 3 . Thes e regiona l designation s are : 1 (Northeast) , 2 (Southeast) , 3 (Southwest) , an

d 4 (West) , an

d sinc e the ycorrespond s o closel y t o th e ozone-pron e regions , the ywil l b e use d a s th e relevan t region s i n subsequen t choice s o f paramete r values . ASTMspecifies , b ystat e an

d month , maximu

mvolatilit y level s whic hca n b e use d bygasolin e distributors . Thes e level s ar e sufficientl yhig ht o ensur e eas e o f engin e start-up , bu t ar e no t s o higha s t o caus e vapo r lock . The yar e identifie d a s classe s AthroughE , wit hAbein g th e lowes t maximu mvolatilit ya t 9. 0 psi , an d E being th e highes t a t 15. 0 psi . Generally , classe s A , B an d C ar e fo r us e i n th e summe r months , whil e D an d E ar e fo r winte r use ; i n eac hseason , th e lowe r volatilit yclasse s ar e specifie d fo r th e hotte r regions . Clas s C volatility , wit ha maximu m allowabl e Rei d Vapo r Pressur e (RVP ) o f 11. 5 psi , i s th e highes t leve l prescribe d fo r th e summer . I t i s widel yprescribe d i n thos e month s i n state s whic hEPAha s identifie d a s ozone-prone , a s ca n b e see n i n Figur e 4 . I t i s clear , a t leas t fromth e ASTMspecification , tha t summertime fuel s ca n hav e significantl yhighe r volatilit ytha n th e 9 ps i RVP o f EPA' s curren t certificatio n fuel . EP Ai s no w i n th e proces s o f examining fue l volatilit yt o mor e accuratel y establis hth e characteristic s o f summertime fuel s fo r th e foreseeabl e future , an d i s therefor e not
- i n a positio n t o definitivel yestablis hit s tes t fue l RVP fo r thi s procedure . I n th e interim , EPAplan s t o requir e th e us e o f 11. 5 ps i fo r tes t fue l volatility . Thi s volatilit yrepresent s th e RV P o f summe r commercia l fue l a s use d i n curren t EPAemissio n factor sFigur e3

Correlatio no f Ozone-pron eStates . (•)an d Radian/APIRegion s flQ^

0 )Figur e 4

Numbe r o f Clas s C (.11. 5 RVP ) Month s

inMa y thruSeptembe r inOzone-pron e State s T )P.1 8

-15

- tes t programs , a s wel l a s th e ASTMclas s C volatilit ylimi t whic hshow s a widesprea d correlatio n wit hth e ozon e pron e area s an d months . Weatherin g o f th e . fue l i n th e vehicl e tank i s als o a facto r i n refueling emissions . Agitation , therma l cycling , temperatur e extremes , an d time aging ca n al l lowe r th e RVP o f th e fue l i n th e vehicle . Th e effect s o f thi s weathere d fue l ar e onl ybeginning t o b e studied ; however , i t seem s tha t tw o counteracting effect s occur . Th e firs t i s tha t th e weathere d fue l i n th e tank ha s a lowe r RVP , an d henc e a lowe r concentratio n o f vapors . Thi s woul d resul t i n lowe r refueling emission s compare d t o non-weathere d fuel , i f refuele d wit h simila r RVP fuel . However , th e fue l bein g adde d i s non-weathered , an

d ther e i s thu s a balancing o f th e pressure s o f th e new , non-weathere d fue l being adde d an d th e older , weathere d fue l i n th e tank . Th e highe r RVP fue l vaporize s a s i t enter s th e tank i n orde r t o equaliz e th e vapo r pressures . Exces s vapor s ar e the n vente d fromth e tank , causing highe r emissions . O f th e tw o effects , th e second i s apparentl ydominan t unde r mos t conditions , according t o limite d data . Thes e dat a come fro

m weatherin g effect s test s conducte d a s par t o f EPA' s baselin e testing fo r refueling emissions[16] , an d froma repor t b yStanfor d Researc hInstitut e concerning refueling.[14 ] Th e EP Atest s involve d dispensing commercia l fue l (RVP o f approximatel y1 2 psi ) int o a tank fille d t o 1 0 percen t o f capacit ywit ha n Indolene-commercia l blend (RV P o f approximatel y1 0 psi) . Th e emission s wer e abou t 2 g/ga l highe r tha n whe n dispensing blende d int o blende d fuel . Thi s wa s apparentl ydu e t o vaporizatio n o f th e commercia l fuel , wit h highe r RVP , a s i t wa s dispense d int o th e tank . I n fact , th e gram s pe r gallo n emission s whe n adding commercia l t o blend fue l (1 2 ps i t o 1 0 psi ) wer e approximatel y1 g/ga l highe r tha n thos e generate d whe n adding commercia l t o commercia l fue l (1 2 ps i t o 1 2 psi) . I n th e Stanfor d study , increase s i n emission s fo r weathere d fue l wer e als o seen . However , thes e increase s wer e significan t onl ywit hlarg e positiv e AT , create d by increasing tank temperatur e whil e holdin g dispense d temperatur e constant . Th e differenc e i n emission s betwee n weathere d an d non-weathere d fuel , increasing wit hincreasing ATs , reache d a hig ho f 1. 7 g/ga l a t th e highes t teste d AT , 35F° . A t A T betwee n 0 an

d 10F° , ther e wa s n o noticeabl e differenc e i n emission s wit hweathere d o r non-weathere d fue l initiall yi n th e tank . I t coul d b e tha t th e lowe r volatilitie s use d i n th eP.1 9

-16

- Stanfor d progra

m(6. 9 an

d 8. 6 psi ) accoun t fo r th e smalle r differenc e see n a t smal l ATs . Fo r th e Stanfor d study , tank fue l RVP wa s abou t 2 0 percen t lowe r tha n dispense d RVP , a t 6. 9 an d 8. 6 psi , respectively . Fo r th e EP Astudy , th e differenc e wa s abou t 1 7 percent . I n a projec t b

ySouthwes t Researc hInstitute , th e amoun t o f weathering a tank o f fue l actuall yexperience s wa s studied . [17 ] Tw o vehicle s wer e eac hdrive n 5 0 mile s a dayan d parke d overnigh t unti l a ful l tank wa s used . Thre e fuel s wer e tested , wit hinitia l RVP s o f 9.0 , 10.5 , an d 12.0 . Fo r eac h fuel , th e RVP droppe d approximatel y9 percen t a s th e tank o f fue l wa s consumed . Verylimite d dat a indicate s thi s valu e may increas e i f th e fue l sit s i n th e tank fo r extende d periods , especiall ywhe n approaching empty . Using th e Southwes t dat a a s an indicato r o f typica l fue l weathering t o b e expecte d in-use , i t appear s tha t fue l weathering coul d increas e refueling emission s byup t o abou t 0. 5 g/gal . However , becaus e o f th e uncertaint yo f thi s amount , couple d wit hth e difficult yo f requiring th e handling o f tw o tes t fuel s an

d th e inherentl yconservativ e natur e o f th e res t o f th e tes t parameters , n o specifi c provision s t o accoun t fo r fue l weathering ar e include d i n th e recommende d practice . 2 . Dispense d Fue l Temperatur e SAE recommende d a dispense d fue l temperatur e o f 82+1°F , whic hwa s th e averag e dispense d fue l temperatur e observe d fo r summe r months , a s reporte d b yScot t Researc hLaboratories.[3 ] However , EPAdesire s t o tes t a t condition s whic hwil l assur e contro l fo r th e majorit yo f cases , rathe r tha n a t averag e conditions . Dat a describe d belo wshow s a 90t hpercentil e poin t o f 88° F fo r dail yaverag e dispense d temperature s i n Maythrough Septembe r fo r ozone-pron e areas . Therefore , th e recommende d practic e use s 88+2° F fo r th e dispense d fue l temperature . Thi s 90t hpercentil e poin t wa s determine d b yEPAusing dat a take n fromth e Radia n repor t analyzing th e gasolin e temperatur e dat a gathere d i n 197 5 b yth e AP I Tas k Force . [4] * Fo r th e month s o f interes t (May-September) , 197 5 temperature s wer e onl yapproximatel y0.2° F highe r tha n th e recorde d historica l averag e (ove r abou t 4 0 years ) fo r th e citie s i n whic hdat a wa s gathered . Therefore , th e ambien t temperature s fo r th e Radia n stud yar e considere d adequatel yrepresentativ e o f norma l conditions .-17

-

I n thi s study , temperature s recorde d wer e o f fue l in : 1 ) th e bul k deliverytank , 2 ) th e underground storag e tank , 3 ) th e dispensing nozzle , an d 4 ) th e vehicl e fue l tank . Fromthi s data , a mathematica l mode l o f dispense d temperatur e wa s formulated , i n whic hth e dispense d fue l temperatur e exponentiall yapproache s eithe r th e underground tank temperatur e (during fil l cycles) , o r ambien t temperatur e (betwee n fil l cycles) , a s a functio n o f cycl e time . Thi s mode l ha s bee n subsequentl yvalidate d b yAPI , an

d mayb e usefu l i n retai l dispense d fue l temperatur e adjustmen t i n th e future . Dispense d temperature s hav e bee n show n t o b e predicte d t o withi n +0. 5 percent . Th e dispense d fue l temperature s actuall ymeasure d i n thi s stud ywer e use d t o determin e th e appropriat e valu e fo r th e tes t procedure . O f specia l significanc e ar e temperature s i n ozon e problemarea s during month s i n whic hozon e effect s ar e significant . Thes e ar e th e four region s whic hcorrespond t o th e ozone-pron e states , show n previousl yi n Figur e 3 , wit hth e critica l month s being MaythroughSeptember . Distribution s o f dispense d fue l temperature s i n eac ho f thes e four region s sho w tha t 5-da

yaverag e dispense d fue l temperature s rang e from5 9 t o 93° F durin g th e month s o f interest.

- Highe r temperature s predominat e i n Regio n 2 (SE) , a s ca n b e se e i n Figur e 5 . Thi s regio n als o ha s a majorit yo f state s wit hfour o r fiv e o f th e fiv e ozone-pron e month s classifie d a s volatilit yclas s C , a s indicate d previousl yi n Figur e 4 . I t migh t b e argue d tha t inclusio n o f Regio n 2 woul d undul y bia s th e dat a towar d highe r dispense d temperatures . However , ther e ar e two othe r factor s whic hmus t als o b e considered . First , th e figur e show s 5-da yaverages , an

d s o doe s no t sho w th e peak s fro

mday s whic hexcee d th e average . Second , th e maximu mdispense d temperatur e o f th e day , calculate d fromth e mode l describe d abov e an d using typica l ambien t temperatur e differentials[4,18] , woul d generall yb e 4 t o 7° F abov e th e average , agai n indicating a nee d t o includ e highe r temperature s (suc ha s thos e foun d i n Regio n 2 ) i n th e tes t procedure . Th e 90t hpercentil e poin t covering al l four region s i s 88° F fo r th e fiv e ozone-pron e month s o f May-September , a s show n i n Figur e 6 . Mor e stringen t condition s coul d b e foun d b y looking a t jus t th e tw o majo r ozon e months , Jul yan d August . Fo r suc hconditions , th e 90t hpercentil e fo r al l four region s combine d i s 9l°F . However , th e fiv e mont hdispense d95 . Figur e 5 Regiona l Dispense d Fue l Temperatur e Five-DayAverage , Summe r 197 5

9 0 . 8 5

80
_ Dispense d Temperatur e 7C - (°F ) /D J

70

- 65 .
60

- ! • 55

- Regio n 1 (NE ) „ Regio n 2 (SE ) ——. . Regio n 3 (SW ) ——— • Regio n 4 ( W ) ' 

# »z r s nI

S » 25 5 T o I S 202 4 J 5Ti b I S 2 0 25 —jnffi " i nu» 5 U1 5 2 0 2 5 MA Y TJUEY " AUGUS T SEPTEMBE R Ozone-Pron eMonth sFigur e 6 Distritaition o f Dispense d Fue l Temperature s Ma ythr u Sep t 1975 , lil yAverages , Region s 1,2, 3 and 4

100-t-12 .

80 .



## S 

# I

- P tH 60 .

20-

- 40-

- 5.0-

-

50t hpercentil e * 80° F 8 5 91

90t hpercentil e a 98<> F &
Dispense dTemperatur e(F° )

T ) h oP.2 3

-20

- temperatur e valu e o f 88° F wa s deeme d mor e representativ e fo r th e ozone-pron e month s overall . 3 . Temperatur e Differentia l Th e differenc e betwee n fue l tank temperatur e an d dispense d temperature , AT , i s a critica l parameter . I t directl y affect s th e magnitud e o f vapo r growt ho r shrinkag e i n th e fue l tank , an

d thu s th e amoun t o f vapo r displace d fromth e tank . Th e SAE recommende d practic e doe s no t indicat e an yparticula r AT , althoughi t doe s stat e a desire d fue l tank temperatur e o f 95+2°F . Thi s value , i n conjunctio n wit hth e recommende d dispense d temperature , give s a A T o f +1 0 t o +1 6 F° . Eithe r paramete r coul d b e specifie d i n th e procedure , bu t AT i s th e paramete r whic hEP Afeel s shoul d b e directl yconstrained , sinc e i t i s s o critica l t o th e leve l o f refueling emissions . I t i s als o th e paramete r tha t wa s recorde d fo r individua l refueling event s i n th e Radian/AP I study , use d abov e t o determin e th e dispense d temperatur e value.[4,5 ] I t i s clearl ydesirabl e t o us e th e same stud

yfo r suc hclosel yrelate d parameters , a s th e dat a wer e gathere d a t th e same station s an d times . I n th e AP I report , A T value s wer e tabulate d separatel y fromdispense d temperatur e values . I n general , direc t correlatio n o f fue l tank t o dispense d temperatur e canno t b e made , becaus e dispense d temperatur e i s strongl ya functio n o f th e slowl yfluctuating underground temperature , whil e fue l tank temperatur e varie s wit hambien t temperature , tri p length , numbe r o f recen t trips , an d s o on . Thus , ther e ar e manyfue l tank temperature s whic hcoul d occu r fo r eac hdispense d temperature . I t i s impossibl e t o tell , fromth e availabl e independen t distributions , exactl yho wth e A T distributio n woul d b e affecte d b ychoosing a give n dispense d temperature . However , th e A

T distribution s b yregio n (Figur e 7) , derive d fromth e AP I report , giv e th e indicatio n tha t thi s proble mmay no t b e significant . O f particula r interes t i s th e distributio n fo r Regio n 2 , whic hwa s identifie d earlie r a s having th e highes t dispense d fue l temperatures . I n term s o f AT , Regio n 2 fall s i n th e middl e ground o f th e regiona l distributions , indicating tha t i t i s reasonabl e t o us e th e averag e A T distributio n wit hth e dispense d fue l temperatur e alread ydeveloped . Tha t is , th e figur e show s tha t th e highaverag e dispense d temperature s foun d i n Regio n 2 d o no t undul yinfluenc e th e corresponding AT distribution . I f anything , th e inclusio n o f Regio n 1 dat a (representing th e lowes t recorde d dispense d temperatures ) wil l tend t o shif t th e A T distributio n towar d mor e positiv e (les sFigur e 7 Cumulative Distribution o f AT = T T -T D

Cunulative Percen t 10 0

9 0 ' 8 0 • 7 0 6 0 5 0 • 4 0 3 0 2 0 . 1 0 • ARegio n 1 , Northeas t 87 8 Vehicle s Q Regio n 2 , Southeas t 29 6 Vehicle s Q Region 3 , Southwes t 32 4 Vehicle s

+ Region 4 , Wes t 39 1 Vehicle s

-2 0 -1 5 -1 0 -5 0 5 1 0 1 5 2 0 2 5 3 0 3 5 4 0

Tan k Temp . - Dispensed Tenp . (°F ) 4 5 5 0 5 5 6 0P.2 5

-22

- stringent ) A

T value s tha n woul d otherwis e b e foun d usin g onl y highdispense d temperatur e data. * Therefore , th e averag e A T distributio n fo r th e four region s combine d wa s use d t o determin e th e 90t hpercentil e valu e fo r th e recommende d practice . Th e basi c distribution s wer e give n i n th e AP I repor t i n tabula r for

mbyincrement s o f 5F ° fo r eac hregio n b ymonth , fo r thos e case s whe n th e ambien t temperatur e wa s betwee n 6 5 an d 85°F** . Fromthese , a distributio n wa s develope d fo r th e ozone-pron e month s (Ma ythroughSeptember ) fo r eac hozone-pron e region . Th e rang e o f A T fo r thes e distribution s i s from-2 0 t o +5 5 F° , wit hnegativ e value s giving vapo r growt ha s th e warme r dispense d fue l enter s th e coole r tank . Sinc e vapo r growt hi s th e mor e stringen t conditio n i n tha t i t create s th e larges t amoun t o f emissions , th e 90t hpercentil e poin t wa s foun d b yaccumulating fromth e top down , tha t is , from positiv e AT . An examinatio n o f th e tabulate d dat a show s tha t th e 90t h percentil e poin t fall s i n th e 0 t o + 5 F ° rang e fo r al l four region s together , a s can b e see n i n Figur e 8 .

* Thi s conclusio n ha s bee n confirmed , b ysubsequen t analysi s performe d byEPAo n th e rawdat a use d fo r th e AP I report . Thes e dat a indicat e that , fo r hig hdispense d fue l temperature s betwee n (8 5 an d 95°F) , th e 90t hpercentil e A T woul d b e slightl ymor e negativ e tha n tha t derive d below , wit ha valu e nea r -3°F . However , EP Aha s decide d no t t o adjus t th e tes t condition s i n orde r t o counte r an y tendenc yfo r th e overal l tes t paramete r se t t o becom e unreasonabl ystringent . Thi s migh t occur throughth e us e o f a 9 0 percen t limi t o f on e paramete r whic hi s itsel f derive d froma 9 0 percen t limi t o f anothe r parameter , thu s defining a conditio n whic hmigh t onl yoccur on e percen t o f th e time . * * Whil e i t woul d b e preferabl e t o hav e th e A T distributio n base d upo n al l ambien t temperatur e conditions , i t wa s no t possibl e t o deriv e thi s informatio n fro mth e tabulate d data . Subsequen t analysi s b yEPAo f th e rawdat a file s ha s verifie d tha t thi s limitatio n di d no t substantiall y affec t th e A

T distributions .Figur e 8 Distribution o f A T = T T - T D Maythru Sep t 1975 , region s 1,2, 3 an d 4

10 0

80-

-



# y & A-3 6 0

40 .

20

-

505 5

Tan k Temp . - Dispense d Temp . (°F )P.2 7

-24

- I t wa s als o determine d tha t th e AT distributio n fo r al l si xregion s - th e 4 8 contiguou s state s - indicate s a mil d vapo r growt hcondition , wit ha 90t hpercentil e valu e i n th e - 5 t o 0 F ° range . Th e desir e fo r a wors t cas e conditio n migh t therefor e indicat e th e choic e o f th e nationwid e A T valu e rathe r tha n tha t foun d fo r th e ozone-pron e region s only . However , ther e i s an importan t reaso n wh ythi s approac hwa s no t adopted . I n 1975 , whe n dat a fo r th e Radian/AP I stud ywa s gathered , veryfe wfue l injecte d (Fl ) vehicle s wer e i n th e fleet . Suc hvehicles , whic har e becoming increasingl ypopula r an d wil l dominat e th e flee t i n futur e years , presumabl yhav e highe r fue l tank temperature s du e t o fue l retur n lines , whic h recirculat e heate d fue l t o th e fue l tank . Therefore , dat a withou t F l vehicle s give s a somewha t smalle r A T tha n migh t b e expecte d fo r F l vehicles . T o provid e some compensatio n fo r thi s situation , EPAha s decide d no t t o us e th e 48-stat e data , an d t o us e th e uppe r en d o f th e 0 t o + 5 F ° rang e fromth e ozone-pron e regions . Providing a rang e fo r testing variability , th e recommende d practic e employ s a AT valu e o f + 2 F ° t o + 5 F° . 4 . Fue l Leve l Prio r t o Refueling Fue l leve l i s importan t a s a vapo r contro l caniste r desig n parameter ; th e caniste r mus t b e size d t o contai n al l o f th e vapor s displace d durin g th e refueling tes t i n orde r t o avoi d breakthrough . Vapo r quantitie s involve d ar e 7 t o 8 g o f H C pe r gallo n o f dispense d fuel , a t th e temperatur e an d RVP condition s specifie d i n th e tes t procedure . A s an exampl e o f sensitivity , thi s translate s int o approximatel yan 1 1 t o 1 3 gramdifferenc e i n emission s pe r 1 0 percen t incremen t i n fue l level , fo r a mediu msiz e 1 6 gallo n tank . Therefore , accuratel yspecifying a fue l leve l prio r t o refil l i s importan t t o assur e in-us e control . Dat a o n fue l leve l prio r t o refil l come s fromstudie s conducte d a s par t o f California' s Stag e I I vapo r contro l program.[6,7,8,9,10,11 ] Thes e studie s observe d refueling event s a t variou s servic e station s i n Californi a t o determin e contro l efficienc yo f Stag e I I systems , and , a s par t o f th e program , reporte d amoun t o f gasolin e dispense d fo r eac h refueling even t tha t too k place . On e study , b yUnio n 76 , provide d fil l fraction s i n th e report , whil e fiv e othe r studies , byUnio n 7 6 ( 2 studies) , Exxon , Healy , an d Emc o Wheato n di d not . However , thes e studie s di d provid e informatio n o n vehicl e make , model , mode l yea r an d fil l amount . EPAestimate d fil l fractio n fo r thes e las t fiv e report s b

yassuming 13 , 1 8 an d 2 3 gallo n tank s fo r compact , mi d an d larg e siz e cars , respectively . Thes e estimate s wer e mad e b yaveraging th e tank sizes , b yvehicl e siz e category , o f 4 4 vehicle s using th e servic e station s i n th e studies .P.2 8

-25

- Th e vehicl e sampl e fo r thes e si xreport s include s 69 6 vehicle s an

d light-dut ytruck s receiving complet e fill-ups . Th e distributio n o f fue l leve l prio r t o refil l fo r thes e vehicle s i s show

n i n Figur e 9 . I t can b e see n that , i n orde r t o cove r 9 0 percen t o f fill-u p events , tank s shoul d b e fille d fromabou t 1 0 percen t o f tank capacit ybefor e refueling . Th e abov e valu e i s take n fro mdat a fo r fill-up s only ; partia l fill s ar e likel yt o hav e sufficien t contro l sinc e purg e rate s ar e highe r whe n th e caniste r i s full yloaded , an d henc e hav e bee n delete d fromthi s dat a base . Th e questio n arises , however , o f ho wmuc htota l fue l i s actuall ydispense d i n fill-ups , an

d ho wman

yevent s ar e fill-ups , i n orde r t o ensur e tha t basing contro l o n fill-u p condition s i s no t unnecessaril y stringent . Th e report s mentione d abov e sho wtha t a substantia l amoun t o f th e fue l dispense d i s par t o f a fill-u p event , suc h tha t ful l contro l b yth e caniste r i s necessary : i n th e four report s whic htabulate d bot hful l an d partia l fills , 5 4 percen t o f th e refueling event s an d 6 2 percen t o f th e gasolin e dispense d wa s use d i n fill-ups . Als o noteworth yi s th e fac t tha t mos t o f th e event s — 8 6 percen t —a t an entirel y full-servic e statio n use d i n on e Unio n 7 6 repor t ar e fill-ups . Therefore , i t i s importan t tha t contro l b e adequat e fo r a ful l refueling . Th e SAE recommende d practic e indicate s tha t th e fue l tank shoul d b e fille d t o one-fourt hcapacit ybefor e th e refueling . I t i s EPA' s desir e t o giv e a mor e precis e specification , a s wel l a s on e whic hduplicate s 9 0 percen t o f actua l refueling events . O n th e basi s o f th e abov e data , thi s valu e ha s bee n chose n t o b e 1 0 percen t o f tank capacity , t o th e neares t one-tent ho f a U.S . gallon . Th e refueling capacit ytes t a s define d i n thi s tes t procedur e wil l b e terminate d whe n automati c nozzl e shutof f occurs . I n orde r t o ensur e adequat e caniste r capacity , thi s automati c shutof f mus t occur whe n th e tank i s a t a leve l betwee n 9 5 an

d 10 0 percen t o f it s nomina l capacity . Thu s th e tota l amoun t o f fil l fo r a vali d tes t wil l b e betwee n 8 5 an d 9 0 percen t o f th e nomina l capacit yo f th e tank . 5 . Fue l Dispensin g Rat e N o valu e fo r a fue l dispensing rat e i s specifie d i n th e SAE recommende d practice . However , thi s i s an importan t paramete r becaus e i t directl yinfluence s th e rat e o f vapo r displacemen t an

d als o th e occurrenc e o f nuisanc e shut-offs , an dFigur e 9 Distribution o f Fue l Leve l Prio r t o Refil l 69 6 Vehicle s

2 0 - .

1 5 - % o f Event s 1 0
_ 13.5 %

5 _ 18.7 % 

### L 

# > f 

# Vi o

• \

19.4 % - ^

18.2 %

0. 1 0. 2 0. 3 15.7 % 10.1 %

3.2 % 

### U0L 0. 4 0. 5 0. 6 0. 7 0. 8

Fue l Leve l Prio r t o Refil l (fractio n o f ful l tank )P.3 0

-27

- perhap s t o some degre e th e amoun t o f fue l spillage . Excessiv e bac k pressur e an

d prematur e nozzl e shut-of f occur s i n a system whic hi s to o smal l t o handl e th e volum e o f fue l bein g dispensed . Thus , th e dispensing rat e affect s th e design o f th e refueling contro l system , an d i t i s necessarytha t thi s paramete r hav e a realisti c value . Avalu e o f 8 t o 1 0 gallon s pe r minut e (gpm ) ha s bee n chose n t o cove r th e majorit yo f fil l events . A198 4 informa l surveyb

yAP I o f membe r companie s an d nozzl e manufacturer s indicate s flowrat e extreme s o f 6. 5 t o 1 2 gpm.[12 ] Lowe r rate s o f 6. 5 t o 8 gp

m ar e foun

d a t full-servic e pumps , wher e th e attendan t maypurposel ychoos e th e lownotc hsetting o n th e fue l nozzl e t o allo wenoughtime t o servic e th e vehicle . Th e lowrat e als o reduce s th e chanc e o f nuisanc e shut-off , whic h ma ycaus e th e nozzl e t o fal l of f th e vehicl e an d caus e larg e fue l spills . Highe r flo wrate s o f 9 t o 1 1 gpmar e typicall y foun d a t self-serv e pumps . Facilit ytyp e als o affect s flowrates . Newer , large r facilitie s generall yhav e submersibl e pump s whic hserv e al l o f th e dispenser s a t eac hunderground tank , an d thei r flo wrate s tend t o b e high , wit ha s muc ha s 10 . t o 1 2 gpmcapability . Older , smalle r station s usuall yhav e individua l suctio n pump s o n eac hdispenser , wit hnorma l rate s o f 8 t o 9 gpm . Al l flow rate s ar e affecte d bysuc hfactor s a s th e numbe r o f vehicle s being refueled , distanc e fromth e pump , ag e o f th e pump , an d vehicl e design constraint s whic hcaus e nuisanc e shut-off . Suc h shut-off s begi n t o occur generall ya t flowrate s abov e 8 t o 9 gpm . Th e nozzl e doe s no t appea r t o b e a significan t facto r i n altering flowrate , althoughi n conjunctio n wit hflowrat e i t ca n affec t fue l spitting . Fromth e availabl e surveys , i t wa s no t possibl e t o quantif ya distributio n o f fue l dispensing rates . However , th e informatio n generall yavailabl e indicate s tha t mos t refueling s tak e plac e a t 1 0 gpmo r less . Highe r rate s ar e possible , especiall ya t newer , self-serv e facilities , bu t ofte n resul t i n nuisanc e shut-off , whic hshoul d b e minimize d belo w1 0 gpmfo r a wel l designe d onboar d system . Therefore , th e specifie d valu e o f 8 t o 1 0 gp

mshoul d cove r th e majorit yo f th e refueling event s whil e minimizin g nuisanc e shut-off . I t i s wort hnotin g tha t Californi a specifie s a 1 0 gp mmaximu

mflo wrat e wit hit s Stag e I I vapo r contro l systems , makin g th e tw o set s o f specification s compatible , whic hi s importan t fo r fue l system design purposes .P.3 1

-28 - D . Vehicl e Preconditioning A variabl e wit hpotentia l fo r affecting th e outcome o f th e tes t i s vehicl e preconditioning . Fo r thi s tes t sequence , ther e are severa l aspect s o f preconditioning , including initia l canister purging , caniste r saturation , an d fue l tan

kheating . Initia l preconditioning ha s bee n describe d earlier , an d involve s ensuring a wel l bu t no t abnormall ypurgedcanister an d a nearl y

empt y fue l tank , s o tha t al l vehicle s wil l hav e bot h canister an

dfue l tank capacit yfo r th e 85 % refueling test . Certificatio

nvehicle s are expecte dt o arriv

e a t the tes t facility

withcanister s purgedt o a leve l commensurat e wit ha nearl y empt y fue l tank . Preparatio nfo r testin

g wil l involv

e drainin g the fue l tank an d fueling t o one-tenthof fue l tan k capacity

(withthe . refueling caniste r disconnected) . In-us e vehicles , o n th e othe r hand , wil l arriv e a t th e facilit yi n variou s conditions ; therefore , suc hvehicle s wil l b e drive n fo r 5 0 mile s o n th e EPAdurabilit ydrivin g schedul e o r equivalen t so tha t th e caniste r can b e adequatel ypurged . Prio r t o thi s mileag e accumulation , th e fue l tank wil l b e draine d an d fuele d wit htes t fuel . Following mileag e accumulation , th e fue l tank wil l agai n b e draine d an d the n fuele d t o one-tent ho f tank capacity . Th e refueling caniste r wil l b e disconnecte d fo r thi s fueling jus t a s fo r certificatio n vehicles . Bot hcertificatio n an d in-us e vehicle s wil l als o hav e thei r ga s cap s loosene d whil e awaiting testing i n orde r t o avoi d an ycaniste r loading during tha t time . Th e specificatio n o f a 5 0 mil e driving schedul e fo r in-us e vehicle s i s stil l tentativ e a t thi s time . EPAbelieve s tha t thi s amoun t o f continuou s driving shoul d b e sufficien t t o purg e eve n a full yloade d caniste r fo r a refueling contro l system capabl e o f passing th e res t o f th e tes t procedure . However , dat a i s stil l being gathere d t o verif ythi s conclusio n an d i t remain s subjec t t o change . Th e Agenc ydesire s t o allo w sufficien t preconditioning t o adequatel ypurg e th e system , bu t als o desire s t o minimiz e th e overal l testing time an d expense . Following th e initia l capacit ytest , i t i s importan t tha t vehicle s be standardizedi n a conditio n whic hwil l permi t th e subsequen t testing t o verif yprope r systempurging . Fo r thi s purpose , the recommende d practic e require s tha t th e caniste r b e full yloade

dfollowing th e capacit ytest . Thi s i s accomplishe d b yputting th e vehicl e i n th e SHE D an d repeatedl yfilling an d draining th e tank ; i n mos t cases , on e o r two fill s shoul d b e enough . Saturatio n i s detecte d bymonitorin g th e SHE DP.3 2

-29

- hydrocarbo n concentratio n wit ha FID ; a sudde n ris e indicate s break-througho f vapor s fro mth e canister . Base d upo n limite d EP A testin

g t o date , th e recommende d practic e define s thi s condition * a s producin g a chang e i n th e FI D reading b ya facto r o f a t leas t 3 i n a on e minut e period . Athir d aspec t o f preconditioning fo r refueling testing i s th e heating o f th e fue l i n th e fue l tank ; thi s bring s th e liqui d an

d vapo r o f th e fue l int o equilibriu m a s wel l a s simulate s th e warme r fue l o f a vehicl e whic hha s bee n driven . Fou r tank heating method s wer e teste d b yEPAa s par t o f th e baselin e refueling emission s study . Th e four procedure s teste d include d thre e type s o f heatin g wit han electri c blanket , an d drivin g ove r a n actua l road route . "Singl e blanket " heating i s th e simples t o f th e preconditioning methods . I t applie s an electri c heating pad t o th e bottomo f th e fue l tank , whic himpart s hea t directl yt o th e liqui d fuel . Thi s procedur e wa s initiall yuse d wit hth e constrain t from

th e origina l SAE recommende d practic e tha t th e temperatur e differenc e betwee n vapo r an d liqui d i n th e tank mus t remai n withi n 6F ° i n orde r t o maintai n equilibriu m throughou t th e hea t build . I t was , therefore , a relativel y long procedure , taking on e an d a hal f t o thre e hour s t o reac h th e desire d temperature , becaus e th e fue l heating mus t b e gradua l i n orde r staywithi n thi s constraint . "Dua l blanket " heating wa s therefor e evaluated , using a second hea t blanke t applie d t o th e top o f th e tank . Thi s metho d heat s th e vapo r a s wel l a s th e liqui d an d allow s mor e rapi d heating withi n th e 6F ° temperatur e differenc e constraint , typicall yrequiring unde r on e hou r fo r hea t build . I t ha s th e drawbac k o f requiring th e remova l o f th e fue l tank t o gai n acces s t o it s top surface . Afina l typ e o f blanke t preconditioning wa s teste d by . EPA i n an attemp t t o eliminat e th e problem s encountere d wit hth e firs t two methods : excessivel yslowhea t build s fo r th e singl e blanket , an

d th e necessit yo f dropping th e tank fo r th e dua l blanket . Thi s preconditioning use s a singl e blanke t bu t remove s th e constrain t o f n o mor e tha n a 6F ° temperatur e differenc e betwee n th e vapo r an d liqui d during th e hea t build . Instead , th e fue l i s heate d t o th e desire d temperatur e a s quickl ya s possible , whic hallow s th e vapo r t o b e heate d muc h mor e rapidl ytha n wit hth e origina l singl e blanke t approach . Onc e th e vapo r temperatur e come s withi n 3F ° o f th e liqui d temperatur e an

d th e temperatur e condition s prescribe d i n th e tes t procedur e hav e bee n reached , a te n minut e waitin g perio d i s begun s o tha t th e vapo r an d liqui d can attai n equilibrium .-30

-

Thi s fas t hea t buil d singl e blanke t metho d o f preconditionin g give s emissio n result s simila r t o th e slowhea t buil d an d dua l blanke t method s a s show n i n Figur e 10 , an d ha s therefor e bee n adopte d fo r th e recommende d practice . Th e fourt hmetho d o f preconditioning allow s heating o f th e fue l byhaving th e vehicl e drive n ove r a n actua l road route . Th e rout e involve s thre e hour s o f rura l an d urba n driving i n th e are a nea r Ann Arbor , Michigan , an d i s run i n orde r t o approximat e a rea l lif e situation . Whil e no t practica l i n itsel f du e t o it s lengt han d potentia l fo r variability , i t confirm s th e appropriatenes s o f blanke t preconditionin g by giving simila r emission s results , a s describe d i n th e baselin e report.[16 ] E . Caniste r Purging an d Vehicl e Drivedown A s mentione d previously , ther e ar e two ke yaspect s o f th e refueling vapo r contro l system whic hmus t bot hb e teste d i n orde r t o assur e tha t emission s ar e bein g properl ycontrolled . Thes e ar e th e capacit yo f th e caniste r whic hcapture s th e vapor s an

d th e capabilit yo f th e systemt o purg e thes e vapor s during vehicl e operation . Thes e aspect s mus t b e teste d withou t affecting th e result s o f othe r portion s o f th e tes t sequence . I t i s als o desirabl e t o kee p cost s lowan d testing tim e a s shor t a s possible , withou t placing an excessiv e burde n o n manufacturers . Al l thi s ha s t o b e accomplishe d whil e maintaining a representativ e an d standardize d test . T o ensur e adequat e purg e design , EP Aha s develope d a vehicl e drivedow

n sequenc e consisting o f consecutiv e LA-4' s an d on e hou r ho t soak s whic har e repeate d unti l approximatel y3 0 percen t o f th e fue l tank capacit yha s bee n consumed . Thi s drivedow

n i s the n followe d b ya 3 0 percen t refueling tes t t o verif ytha t th e systemha s purge d sufficien t vapor s t o handl e a proportionat e refueling . Subsequen t analysi s o f thi s drivedown requiremen t indicate s tha t i t mayno t b e neede d i n al l cases . Dependin g o n th e desig n o f th e refueling contro l system , th e tes t sequenc e frominitia l caniste r capacit ytesting an d subsequen t saturatio n throughth e remainde r o f th e existing FT P ma yb e sufficien t t o ensur e adequat e refueling systemperformance . Fo r thos e refueling contro l system s whic har e full yo r partiall yintegrate d wit hth e vehicle' s evaporativ e emissio n controls , a substantia l amoun t o f systempurg e i s require d t o pas s th e diurna l evaporativ e tes t following th e initia lFigur e1 0

O 

# 1 3 3 

# COMPARISO N O F REFUELIN G LOSSE S

R n — , O ,L J 

### 7. 5 

### - 7. 0 

### - 6. 5 

### - 6. 0 

### - 5. 5 

### - 5. 0 

### - 4. 5 

### -

A. n _i •"+ . u 

### +

i ESCOR T- DISP.TEMP. = 8 G RVP=11. 9

D D 

### n D + - + +

D + . • 

### +

1 1 1 1 1 i 1 1 1 1 a D &

1 1 1 •2. 0 0. 0 2. 0 STANDAR D HEA TBUIL D 4. 0 6. 0 8. 0 DELT AT(DEGREE S F ) 10. 0 12. 0 FAS THEA TBUIL D 

### 14. 0

co J >P.35
_

-32

- caniste r saturatio n step , an d i t mayb e tha t th e stringenc yo f thi s requiremen t i s sufficien t t o ensur e tha t th e vehicl e wil l als o purg e collecte d refueling vapor s ove r th e cours e o f th e drivedow

n sequence . A s an initia l tes t o f thi s hypothesis , EP Aevaluate d th e amoun t o f vapor s require d t o b e purge d fo r complianc e wit hth e diurna l evaporativ e emission s tes t i n compariso n wit hth e amoun t o f purg e require d t o satisf yth e drivedow n requirement . Thi s wa s initiall ydon e o n th e assumptio n tha t th e refueling caniste r ha d a linea r purg e respons e a s a functio n o f caniste r loading . Wit hthi s assumptio n th e calculate d purg e rat e fo r passing th e diurna l tes t wa s approximatel yte n time s th e purg e rat e neede d t o pas s th e drivedown , an d th e drivedown appeare d t o b e unnecessary . EPAthe n repeate d th e analysis , incorporating a n estimat e o f th e actua l non-linea r purg e characteristic s expecte d from th e refueling canister . O n thi s basis , th e diurna l tes t requiremen t wa s onl ymarginall yadequat e fo r ensurin g sufficien t refueling purge . Th e analysi s als o indicate d that , sinc e th e caniste r purg e rat e continue s t o declin e a s th e caniste r i s purged , a 3 0 percen t drivedow n ma yno t b e adequat e t o accoun t fo r systemperformanc e a s an empt ytan k i s approached . A t thi s time i t i s unclea r whethe r th e drivedown i s neede d fo r integrate d systems , o r i f i t is , whethe r a 3 0 percen t drivedow

n amoun t i s sufficient . EPAi s currentl yi n th e proces s o f gathering mor e dat a o n th e purg e characteristic s o f refueling an

d evaporativ e canister s an d o n way s t o avoi d th e nee d fo r an extende d vehicl e drivedown . On e optio n bein g considere d i s t o replac e th e drivedow n wit hth e requiremen t tha t th e refueling caniste r remai n connecte d during th e 4 0 percen t fil l preceding th e diurna l evaporativ e emission s test . Th e adde d purg e require d b ythi s approac hmaytur n ou t t o correspond wel l wit hth e performanc e characteristic s o f a refueling system

capabl e o f full ypurging collecte d refueling vapors , an

d thu s eliminat e th e nee d t o furthe r demonstrat e purg e capabilit yvi a a drivedown . Fo r refueling contro l system s whic hemplo yseparat e canister

- system s fo r refueling emission s an d evaporativ e emissions , th e drivedow n sequenc e appear s t o b e unavoidable . Th e completel yseparat e refueling systemincur s n o loading from evaporativ e emissions , s o tha t th e adequac yo f th e purg e canno t b e teste d during th e preconditioning cycl e an d evaporativ eP.3 6

-33

- loading sequenc e i n th e FTP . I n thes e instances , then , th e purg e tes t wil l hav e t o b e conducted , involving th e 30 % drivedown/refueling sequenc e appende d t o th e usua l sequence . A t thi s time , th e draf t recommende d practic e include s a drivedow

n requiremen t fo r onl ythos e vehicle s employing a non-integrate d refueling contro l system . I t remain s possible , however , tha t th e drivedow n requirement , o r som e othe r modificatio n t o th e tes t sequence , ma yb e neede d fo r integrate d systems . F . Testing Requirement s fo r In-Us e Vehicle s I t i s EPA' s inten t tha t moto r vehicle s mee t emission s standard s throughou t thei r usefu l life , i n orde r t o bes t protec t th e publi c an d environmen t fromth e harmfu l effect s o f mobil e sourc e pollutants . Certificatio n o f ne wmoto r vehicle s is , o f course , on e majo r aspec t o f assuring tha t onl yvehicle s likel yt o hav e lowemissio n level s in-us e ar e produced . I n orde r t o ensur e tha t productio n vehicle s continu e t o mee t th e standard s throughou t thei r usefu l lives , EPAroutinel yperform s test s o n in-us e vehicles , following th e certificatio n testin g procedur e a s closel ya s possible . However , some adjustment s t o th e procedur e ar e neede d t o accommodat e in-us e situation s whic h ar e distinc t fromcertificatio n testing . EPA' s proposal s fo r handling th e uniqu e aspect s o f in-us e emission s testing ar e discusse d i n thi s section . Include d ar e th e procedure s t o standardiz e th e vehicle s vi a preconditioning , a s wel l a s potentia l testing problem s no t encountere d wit h specially-equippe d certificatio n vehicles . Thes e issue s hav e largel ybee n identifie d b ymanufacturers , an d EPA' s approache s t o resolving themar e outline d here . Th e Agenc yremain s ope n t o furthe r comment s o n preconditioning an d testing o f refueling emission s fromin-us e vehicles . 1 . Preconditioning Problem s Residenc e Time Befor e Testing I t i s important , fo r full yo r partiall yintegrate d systems , tha t vehicle s no t stan d wit ha close d systemfo r extende d period s o f time prio r t o th e refueling test , a s thi s maycaus e loading o f th e caniste r whic hi s unrepresentativ e o f a vehicl e whic hi s drive n regularly . However , whil e vehicle s ar e teste d a s soo n a s possible , i t i s no t possibl e fo r EPAt o assur e tha t everyvehicl e brough t t o th e tes t sit e wil l b e teste d soo n afte r arrival , du e t o fluctuation s i n vehicl eP.3 7

-34

- procuremen t an

d tes t site/technicia n availability . Therefore , i n orde r t o kee p th e leve l o f caniste r loading down , th e refueling systemwil l b e opene d byloosening o r removing th e ga s ca p t o allo wth e escap e o f vapors . I t shoul d b e note d tha t certificatio n vehicle s ca n als o hav e thei r ga s cap s loosene d upo n arriva l a t th e tes t site . Residua l Fue l Th e variet yo f th e RVP o f fuel s i n th e tank s o f in-us e vehicle s coul d caus e excessiv e variatio n i n tes t result s i f suc hfuel s wer e allowe d t o remai n i n th e tank . Therefore , vehicle s wil l hav e thei r tank s draine d o f residua l fue l an d wil l b e preconditione d an d teste d onl ywit hth e specifie d tes t fuel . Fo r presen t testing , suc hfue l wil l hav e a n RVP o f 11.5+0. 5 psi ; th e fue l t o b e use d i n actua l certificatio n an d in-us e enforcemen t testing wil l b e specifie d afte r furthe r investigation , an

d wil l b e simila r t o averag e in-us e fuels . Manufacturer s hav e als o expresse d concer n tha t consume r us e o f highRVP fuel s wil l caus e long-ter meffect s o n th e refueling and/o r evaporativ e systemwhic hwil l significantl y affec t tes t results . Thes e concern s are , i n th e Agency' s opinion , unwarranted . Firs t o f all , a s alread ynoted , EP Ai s changing it s tes t fue l t o mor e closel ymatc hin-us e fuels . Therefore , normall yavailabl e fuel s shoul d no t diffe r widel y fromcertificatio n fuels . Secondly , vehicle s shoul d b e designe d s o tha t system s ar e no t permanentl ydisable d byth e us e o f an

ynormall yavailabl e fuel , an d i n fac t shoul d remai n largel yoperational . Anylos s i n functio n shoul d b e restore d b yadequatel ypreconditioning wit hth e tes t fuel . Thi s i s no t t o sa ytha t concer n abou t suc hthing s a s alcoho l additives , whic hma ydamag e emissio n control s i f use d improperly , i s unwarranted . Suc han issu e i s simpl ybeyond th e scop e o f thi s proposal , an

d mus t b e deal t wit hseparately . Finally , manufacturer s hav e expresse d a desir e tha t th e tes t fue l use d fo r residua l tank fue l b e weathered , i.e. , hav e a lowe r RVP tha n th e dispense d fuel . EPAha s considere d th e us e o f weathere d fuel , a s describe d earlier , an d decide d agains t it . Weathere d tank fue l increase s emission s slightly , bu t no t enought o warran t th e adde d complexit yo f handlin g tw o tes t fuels . Suc ha decisio n shoul d no t b e objectionabl e t o manufacturer s sinc e i t reduce s th e stringenc yo f th e tes t somewhat .-35

-

In-Us e Driving Pattern s Th e driving pattern s encountere d in-us e ca n affec t refueling emission s contro l byaltering th e purg e capabilit yo f th e refueling system . Permanen t damag e t o th e systemcause d by a lowtri p frequenc yan d corresponding lowleve l o f purg e i s a manufacture r concern , but , i n Agenc yopinion , shoul d no t occur . Lik e th e effect s o f variou s fuels , a rang e o f norma l driving pattern s shoul d no t caus e an yirreversibl e disablemen t o f systems ; tha t is , vehicle s shoul d b e designe d t o withstand th e vas t majorit yo f in-us e conditions . Aprope r preconditioning cycl e shoul d b e abl e t o standardiz e vehicle s whic hwil l hav e arrive d a t th e tes t sit e unde r a variet yo f driving conditions . Th e procedur e currentl yt o b e use d involve s drivin g th e vehicl e fo r 5 0 mile s o n th e durabilit ydriving schedul e o r equivalent , o n a tank o f standar d tes t fuel . Thi s i s intende d t o allowth e systemt o purg e th e canister , thereb yrestoring th e system , an

d shoul d adequatel ystandardiz e th e purg e leve l o f in-us e vehicle s fo r subsequen t testing . A s note d i n earlie r discussio n o f vehicl e preconditioning , EPAi s ope n t o commen t shoul d manufacturer s hav e informatio n showing tha t thi s preconditioning cycl e wil l no t mee t thei r needs , o r hav e suggestion s fo r alternativ e preconditionin g fo r caniste r purge . Fue l Tank Heatin g An additiona l aspec t o f preconditioning involve s fue l tank heating , whic hfurthe r standardize s th e vehicle s byattaining a uniformtank temperatur e an d liquid/vapo r equilibrium . Tank heating i s ofte n don e usin g th e dua l blanke t metho d discusse d i n Sectio n III.D. , whic hwa s originall ypresente d byEP Aa s th e chose n metho d fo r refueling testing . However , thi s metho d present s practica l problem s fo r in-us e vehicles , sinc e i t involve s dropping th e fue l tank from it s norma l position . O n th e othe r hand , th e traditiona l singl e blanke t method , wit ha constrain t o f a maximu m 6F ° differenc e betwee n liqui d an d vapo r fue l temperatures , require s severa l hour s t o complete , an d s o i s als o undesirable . I n respons e t o thes e problems , a ne wmetho d wa s devise d whic hi s muc hquicke r tha n th e origina l singl e blanke t metho d an d require s n o majo r alteration s o f the . vehicle . Thi s metho d allow s rapi d heating o f th e liqui d wit hth e us e o f a singl e blanke t applie d beneat hth e tank . Upo n arriva l o f th e liqui d fue l a t th e specifie d temperature , th e vapo r an d liqui d ar eP.3 9

-36

- allowe d t o com e int o equilibriu mduring a 1 0 minut e waitin g period , onc e the yar e withi n a 3F ° difference . Rapi d singl e blanke t heatin g give s result s comparabl e t o othe r methods , an d i s th e metho d tha t wil l b e use d o n in-us e vehicle s t o sav e tim e an d kee p consume r vehicl e fue l system s intact . 2 . Testing Problem s Caniste r Disconnec t Th e recommende d practic e contain s severa l step s whic h requir e th e refueling caniste r t o b e disconnecte d i n orde r t o avoi d excessiv e loading wit hvapors . Manufacturer s hav e expresse d th e concer n tha t th e caniste r ma yb e inaccessibl e fo r disconnect , an

d tha t th e integrit yo f th e vapo r lin e sea l upo n reconnec t ma yb e suspect , causin g leak s o r spillage . I t i s EPA' s expectatio n tha t th e easies t wa yt o allo wfo r th e refueling caniste r t o b e disconnecte d fo r testing wil l b e throughth e insertio n o f a valvin g mechanis mi n th e vapo r line . Thi s woul d b e don e during initia l vehicl e preparation , allowing adequat e opportunit yfo r th e integrit yo f th e vapo r lin e seal s t o b e verified . Thereafter , th e require d caniste r disconnect s ca n b e produce d throughsimpl e operatio n o f th e valve . A s fo r accessibility , EPAdoe s no t believ e tha t th e requiremen t fo r vapo r lin e accessibilit ypose s an yseriou s desig n constrain t t o manufacturers . Tes t Void s Test s whic hd o no t mee t specification s wil l nee d t o b e aborte d an

d rerun , an

d i t i s apparen t tha t thes e vehicle s wil l nee d t o b e res t andard i ze d an d reente r th e tes t sequenc e a t an appropriat e point . Fo r th e refueling tes t ther e ar e severa l convenien t place s wher e partia l testing ca n b e restarte d t o avoi d havin g t o rerun th e entir e sequenc e i n th e cas e o f a tes t void .Fo r thos e vehicle s whic hhav e no t complete d th e initia l refueling capacit ytest , th e prim e concer n wil l b e t o retur n th e caniste r t o a purge d conditio n simila r t o tha t wit hwhic h i t entere d th e test . Thi s ca n b e accomplishe d b yrecycling th e vehicl e throughth e preconditioning sequenc e fo r in-us e vehicle s (5 0 mil e driv e sequence ) an d beginning th e testing anew .P.4 0

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- Fo r vehicle s whic hhav e complete d th e refueling capacit y tes t an d subsequen t caniste r saturation , bu t whic hhav e no t ye t complete d th e diurna l test , i t wil l b e sufficient , i n th e even t o f a tes t void , t o retur n t o th e caniste r saturatio n ste p an d procee d fromthere . Subsequen t t o th e diurna l tes t an d prio r t o beginning th e drivedow n test , th e curren t FT P remain s essentiall yunchange d an d tes t void s ma yb e handle d according t o curren t practice . Th e las t portio n o f th e refueling tes t i s th e drivedown an d partia l refueling test . Ates t voi d durin g th e refueling operatio n her e ca n b e accommodate d b ycompleting th e prescribe d amoun t o f fill , repeating th e drivedow n sequenc e (appropriatel y calculating th e require d amoun t o f driving an d refueling ) an

d repeating th e refueling test . A s th e abov e discussion s indicate , EP Abelieve s tha t th e recommende d practic e a s currentl ydesigne d adequatel ydeal s wit hissue s o f concer n relativ e t o testing in-us e vehicles . O f course , EP Ai s alway s ope n t o furthe r comment s concerning th e appropriatenes s o f thes e solutions , an d t o alternat e solution s shoul d thes e b e deeme d unsatisfactory .P.4 1

Reference s 1 . "Evaluatio n o f Ai r Pollutio n RegulatoryStrategie s fo r Gasolin e Marketing Industry, " (EPA-450/3-84-012a) , U.S . EPA , OAR , OAQP S an

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C Dispensing Nozzle s - Attendan t Serv e Operating Mode, " Scot t Environmenta l Technology , Augus t 30 , 1979 . 9 . "Heal yPhas e I I Vapo r RecoverySystemCertificatio n Report, " Scot t Environmenta l Technology , Jun e 1982 . 10 . " AServic e Statio n Tes t o f a Vapo r Balanc e Systemfo r th e Contro l o f Vehicl e Refueling Emissions, " A.M . Hochhause r an d L.S . Bernstein , Exxo n Researc han d Engineerin g Company , Jul y1 , 1976 . 11 . "Efficienc yEvaluatio n o f Emc o Wheato n A300 6 Dispensin g Nozzle, " Scot t Environmenta l Technology , Jul y8 , 1981 .Reference s Cont'd .

12 . Letter fro

m Edwar dP . Crockett , AmericanPetroleu m Institute , t o Charle s L . Gray , U.S . EPA , regardin g fue l flo

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Stud y of Variable s tha t Affec t the Amount of Vapor EmittedDurin

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dResearchInstitute , Ma y 16 , 1975 . 15 . "1981-8 3 Standar dMetropolitanStatistica l Are a (SMSA ) Ai r Quality

Dat a Bas e fo

r Us e inRegulator y Analyses, " Technica l Memorandu

m fro m RichardG . Rhoads , U.S . EPA , MD-14 , t o Charle s L . Gray , U.S . EPA , OMS , Februar y 25 , 1985 . 16 . "Refuelin

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m UncontrolledVehicles, " Dal e Rothma nan dRober t Johnson , EPA-AA-SDSB-85 - , Jul y 1985 . 17 . "Fue l Volatility Trends, " Fina l Report , Lette r fro m Bruc e B . Bykowski , Southwes t ResearchInstitute , t o Crai g Harvey an dAm y Brochu , U.S . EPA , September 28 , 1984 . 18 . The Weather Almanac , Thir dEdition , Jame s A . Ruffne r an d Fran kE . Bair , Ed. , Gal e ResearchCompany : Detroit , 1981 .



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