P. 1



# OAR Box 1856 Prepped byKeeia Richards



### Document

Number: 

# 80 ) ll-A-1 7 Docket Number: 

# A-87-1 1

Printed 11/24/2008 12:41:51 PM Sheet 80 of 82

# V P. 2 EPA-AA-SDSB-87-0 5

Technica l Repor t

Safet yImplication s o f Onboar d Refueling

Vapo r RecoverySystem s

Jun e 198 7
FINAL REPORT

Technica l Report s d o no t necessaril yrepresen t fina l EP A decision s o r positions . The yar e intende d t o presen t technica l analysi s o f issue s usin g 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 hma yfor mth e basi s fo r a fina l EP A decision , positio n o r regulatoryaction .

Standard s Developmen t an d Suppor t Branc h Emissio n Contro l Technolog yDivisio 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 

## V EPA-AA-SDSB-87-0 5

Technica l Repor t

Safet yImplication s o f Onboar d Refueling

Vapo r RecoverySystem s

Jun e 198 7
FINAL REPORT

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 EP A 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. 4 

## V Tabl e o f Content s Sectio n Pag e

I . Executiv e Summary3
II . Introductio n 7
III . Onboar d Contro l SystemDescriptio n 9
IV . Desig n Consideration s for a Saf e System2 7
V . In-Us e Fue l SystemSafet y5 0
VI . Cos t an

d Leadtime Consideration s 6 1
VII . Heavy-Dut yGasolin e Vehicl e Requirement s 7 4 VIII . Conclusio n 9 5
IX . Reference s 9 7P. 5 

### -3

- I . Executiv e Summary Th e purpos e o f thi s technica l repor t i s t o evaluat e th e safetyimplication s o f requiring onboar d refueling vapo r recover ysystem s o n gasoline-powere d passenge r cars , ligh t truck s an

d heavy-dut yvehicles . I n tha t light , specia l attentio n i s give n t o th e analysi s o f th e desig n consideration s for a saf e onboard systeman d th e othe r measure s necessaryt o insur e tha t th e desig n consideration s incorporate d ar e capabl e o f providing a highleve l o f in-us e fue l systemintegrity . Onboar d refueling system s ar e i n man yway s simila r t o presen t fue l tan

k evaporativ e emissio n systems . Th e emission s emanat e fro

mth e same locatio n o n th e vehicl e an d th e basi c technolog

yuse d t o contro l th e two type s o f emission s i s quit e similar . Man

yo f th e component s ar e analogous , i f no t essentiall yidentical , an d th e configuration/layou t o f th e system s o n th e vehicl e i s als o expecte d t o b e abou t th e same . I n fact , thes e two system s an d systemfunction s ar e s o simila r tha t man

ymanufacturer s wil l likel ycombin e thei r onboar d refueling an

d fue l tank evaporativ e emissio n system s int o on e integrate d systemwhic hca n serv e bot hpurposes . Th e fac t tha t thes e system s ar e simila r an d wil l b e integrate d ha s two effect s o n th e safet yo f onboar d systems . First , man yo f th e approache s an

d technique s use d t o safel yimplemen t evaporativ e emissio n contro l system s ca n als o b e applie d t o insur e th e saf e implementatio n o f an integrate d onboar d refueling/evaporativ e emissio n system . Second , an ysafet yproblem s relate d t o integrate d onboard/evaporativ e system s shoul d b e evaluate d incrementa l t o presen t evaporativ e systems . Quit e simply , ther e i s n o nee d t o ad d a whol e ne wsystemt o th e vehicle . Concern s ove r th e potentia l safet yimplication s o f onboar d system s have , however , bee n raised . Thes e concern s ca n b e groupe d int o four genera l areas . Thes e includ e requirement s t o pas s th e Nationa l HighwayTraffi c Safet yAdministratio n (NHTSA ) safet ytests , th e effect s o f tampering an d systemdefects , refueling operations , an d in-us e fue l systemsafety . Concern s wit hth e desig n requirement s necessaryt o compl y wit hth e NHTS Asafet ytest s focuse d o n th e nee d t o integrat e a n onboar d systemint o a vehicl e i n a manne r whic hwoul d provid e th e crashworthines s an d rollove r protectio n demande d b yFedera l Moto r Vehicl e Safet yStandar d (FMVSS ) 301 . EPA' s analysi s indicate s tha t crashworthines s fo r th e keyvapo r line s an d othe r systemcomponent s coul d b e accomplishe d usin g man yo f th e same approache s an d technique s no wapplie d successfull yt o evaporativ e emissio n systems . Further , th e rollove r protectio n no wprovide d fo r th e fue l tan k throughth e us e o f a limiting orific e ca n b e gaine d throughth e applicatio n o f on e o f th e severa l rollove r valv e design s no wavailable .P. 6

v 4 

### -4

-

Concern s hav e als o bee n expresse d tha t caniste r tampering an d componen t defect s coul d lea d t o in-us e safet yproblems . Whil e caniste r tampering i s infrequent , th e rat e ca n b e reduce d an d the potentia l safet yeffect s eliminate d throughprope r placement . Manufacturer s ar e expecte d t o conside r th e safet y implication s o f tampering whe n evaluating caniste r locatio n option s o n th e vehicl e a s theyd o no wwit hevaporativ e contro l syste mcanisters . Whil e th e concer n ha s bee n expresse d tha t defect s i n onboar d systemcomponent s coul d hav e safet y implications , n o dat a o r othe r base s hav e bee n foun d tha t sugges t onboar d system s woul d influenc e th e natur e o r frequenc y o f suchoccurrence s a s compare d t o thos e see n o n curren t evaporativ e emissio n systems . I n fact , give n th e experienc e gaine d b

yth e manufacturer s i n safel yimplementing evaporativ e controls , i t i s likel ytha t a n integrate d onboard/evaporativ e syste mcoul d b e implemente d wit hn o mor e (an d perhap s less ) problem s than presen t evaporativ e emission s systems . Concern s ove r th e safet yo f refueling operation s ar e centere d o n th e potentia l t o overpressuriz e th e fue l system . EPA' s analysi s find s tha t us e o f a liqui d sea l solve s al l overpressur e problems , an d tha t i f a mechanica l sea l i s use d a simpl e pressur e relie f devic e can b e use d t o eliminat e an y overpressur e concerns . A s discusse d i n th e analysis , a few othe r les s significan t potentia l problem s hav e very straightforwar d engineering solutions . Finally , whil e i t i s clea r tha t onboard-equippe d vehicle s can b e designe d t o compl ywit hFMVS S 30 1 requirements , ther e ha s bee n concer n expresse d tha t fue l systemintegrit yin-us e maydecreas e b

ysome non-quantifiabl e amoun t becaus e FMVS S 30 1 can' t cove r al l potentia l acciden t situation s an d an onboar d syste mrequire s modification s an d addition s t o th e presen t evaporativ e emissio n system . Whil e n o tes t procedur e ca n cove r al l potentia l situations , i t doe s no t necessaril yfollowtha t systemmodification s o r addition s wil l caus e an increas e i n ris k ove r presen t systems . Bot hvehicl e an

d fue l systemsafet yar e evaluate d a s an integra l par t o f th e overal l design an d developmen t process . Thi s involve s multipl e trade-offs , balances , an d compromise s wit hothe r ke ydesign considerations . Give n th e nee d t o conside r al l keydesign criteria , manufacturer s accep t or manag e a certai n amoun t o f risk . Sinc e th e safet ydemand s o f Federa l standard s suc ha s FMVS S 30 1 mus t b e incorporate d int o vehicles/systems , thes e standard s represen t th e minimum . I n man ycase s th e leve l o f safet yachieve d in-us e goe s beyond tha t require d b

yFedera l standards , being drive n b yin-us e liabilit y concerns .P. 7

> i 

### -5

- I f a manufacture r perceive s tha t th e adde d ris k mentione d above mayexis t fo r on e o r mor e o f it s vehicl e models , ther e ar e way s t o respon d throughdirec t measure s o r throughkeeping th e overal l ris k in-us e a t acceptabl e level s throughothe r design flexibilities . EPA' s analysi s identifie s an d describe s a numbe r o f thes e measures . Manufacturer s can mak e vehicle s safe r than theyar e now ; an onboard requiremen t doe s no t increas e th e amoun t o f ris k a manufacture r nee d incur or accept . Manufacturer s ar e expecte d t o integrat e onboar d control s int o thei r fue l system s withou t compromising safety . Further , a s par t o f overal l ris k management , implementing onboard control s provide s th e opportunit yt o improv e overal l fue l handling an

d fue l systemsafety . Refuelin g spill s wil l b e reduce d an

d flammabl e vapor s wil l b e trappe d i n th e caniste r instead o f being vente d ou t th e fillpip e nea r th e nozzl e operato r wher e inadverten t ignitio n i s possible . Also , installing rollove r valve s coul d improv e th e saf.e.t yfo r thos e vehicle s no wusing externa l fillpip e ven t line s withou t rollove r valves . Th e positiv e sea l provide d b ya rollove r valv e i s an improvemen t ove r th e "controlle d leak " rollove r protectio n currentl yprovide d b ya limiting orifice . I n addition , implementing onboar d system s coul d furthe r enhanc e safet yb

yprovidin g th e opportunit yt o mak e othe r safet y relate d fue l system s change s whic hhav e bee n delaye d fo r economi c or othe r reason s (e.g. , changing fromrea r t o sid e fill) . Finally , i f a manufacture r choose s t o us e a collapsibl e fue l bladde r t o contro l refueling emissions , thi s woul d eliminat e al l o f th e potentia l concern s raise d relativ e t o th e caniste r base d onboar d system , an d woul d provid e improvement s i n safet yove r th e presen t fue l system . Othe r keyconsideration s includ e safet yrelate d cost s an d th e leadtime neede d t o implemen t onboar d control s safely . Thi s analysi s estimate s tha t safet ycost s relate d t o implementing . onboard system s wil l rang e fro m$4.50-$9.0 0 pe r vehicle . Whil e th e cos t estimate s fo r th e neede d hardware , modification s an d fue l consumptio n impact s ar e reasonabl yaccurate , ther e i s some uncertaint yi n th e developmen t an d safet ycras htesting cos t estimates . However , safet yrelate d onboar d cost s ar e quit e insensitiv e t o eve n larg e change s i n th e estimate s fo r developmen t an

d safet ycertification . I n a genera l sense , EPA' s estimate s ar e supporte d b yth e fac t tha t th e modification s neede d fo r presen t vehicle s t o insur e fue l systemsafet yin-us e hav e bee n acquire d relativel y inexpensively , an

d vehicle s wit hevaporativ e emissio n system s compl ywit hFMVS S 30 1 today . Muc ho f th e groundwor k neede d t o implemen t an integrate d onboar d refueling/evaporativ e emissio n contro l systemsafel yha s bee n complete d an d man yo f th e sameP. 8 

### -6

- technique s an

d approache s can b e used . Th e fac t tha t integrated system s wil l b e use d mean s tha t some cost s incurre d t o implemen t evaporativ e emission s system s safel ywil l no t reoccur . EPA' s analysi s ha s adequatel yaccounte d fo r safet y cost s i n it s estimat e o f th e tota l onboar d system cost . Safet y cost s contribut e abou t 2 5 percen t o f th e $2 0 cos t estimate d for a passenge r ca r onboar d system . Wit hregard t o leadtime , give n th e magnitud e o f th e tas k an d pas t experienc e wit himplementing evaporativ e emissio n an d fue l system

integrit ystandard s (FMVS S 301) , thi s analysi s indicate s tha t 2 4 month s leadtime i s adequate . However , EPAi s committe d t o providing th e leadtime neede d t o implemen t onboard control s safel yan d effectively , an d i s ope n t o considering additiona l leadtime or a shor t phase-i n o f control s t o assis t manufacturer s in dealing wit hproblem s o n uniqu e vehicl e models . Finally , th e onboard system s whic hwoul d be_ . installe d o n HDGV s ar e quit e simila r t o thos e expecte d for passenge r car s an d light trucks , eve n thoughth e safet ytes t requirement s ar e differen t fo r HDGVs . Wit hth e exceptio n o f schoo l buses , th e fue l systemintegrit ytesting center s mor e o n evaluatio n o f fue l tan

k integrit ythan vehicl e cras htesting . Nevertheless , man yo f th e concern s raise d an d addresse d abov e regarding onboard safet yfo r lighter-weigh t vehicle s als o appl yt o HDGV s an d suppor t th e judgmen t tha t onboar d system s can b e applie d safel yt o thi s clas s o f vehicle s withi n th e leadtime lai d ou t above an

d fo r a reasonabl e cost .PJ _ 

# i : 

# " -7

- II . Introductio n EPAha s receive d severa l comment s from th e Moto r Vehicl e Manufacturer s Association , Automobil e Importer s o f Americ a (an d thei r membe r companies) , an d th e . Insuranc e Institut e fo r Highwa ySafet ywhic hhav e expresse d variou s level s o f concer n abou t th e potentia l safet yimplication s o f onboar d vapo r recover ysystems.[1,2 ] Also , some preliminarycomment s regarding onboar d safet yhav e bee n receive d fro mNHTSA' s technica l staff.[3 ] Th e America n Petroleu m Institut e (whic h ha s independentl ydevelope d severa l onboard-equippe d vehicles ) an d th e Cente r fo r Aut o Safet yhav e expresse d suppor t for th e implementatio n o f onboar d vapo r recoverysystems.[4,5 ] Th e purpos e o f thi s repor t i s t o discus s an d analyz e th e safet y relate d concern s raise d regarding onboar d vapo r recovery systems . Moto r vehicl e manufacturer s fac e man ydifficul t technica l decision s i n th e desig n an d developmen t o f vehicl e . system s an d th e integratio n o f thes e system s int o ne wvehicl e models . Th e difficult yo f thes e decision s ofte n arise s fro m th e fac t tha t thi s design , developmen t an d integratio n proces s require s th e simultaneou s consideratio n o f a numbe r o f ke ycriteria . On e o f th e mos t importan t o f thes e criteria , safety , i s normall ygive n a highpriorit yi n th e design an d integratio n process . However , th e proces s als o include s carefu l an d pruden t consideratio n o f th e trade-off s necessaryt o dea l wit hothe r importan t criteri a suc ha s performance , reliability , cost , styling , an

d regulatoryrequirement s suc ha s fue l econom yan d emissions . I n eac hcase , manufacturer s mus t fin d th e appropriat e balanc e o f al l th e importan t criteria . Sinc e th e design o f emissio n contro l system s ha s th e potentia l t o affec t th e overal l safet yo f vehicles , EPAview s safet ya s a primary concer n whe n evaluatin g th e feasibilit yo f a n emissio n contro l device . EPAi s presentl yevaluating th e us e o f onboar d vapo r recoverysystem s (onboar d systems ) a s a mean s o f controlling refueling emissions . Th e potentia l safet yimplication s o f suc h control s requir e specia l consideration , becaus e implementing onboar d system s wil l involv e some mino r modification s o f th e vehicl e fue l system . Whil e safet yinfluence s al l aspect s o f vehicl e design , fue l systemsafet yan d integrit yi s a ke y concer n i n th e desig n an d integratio n process . I n evaluating th e safet yimplication s o f requiring onboar d controls , EP Aha s applie d th e philosoph ytha t n o increas e i n overal l ris k shoul d b e cause d o r accepted , beyond tha t no w presen t wit htoday' s fuel/evaporativ e system . Thi s applie s t o bot hcomplianc e wit hth e applicabl e Federa l safet ystandard sP.1 0 V -8

-

an d the in-us e safet yo f vehicle s equippe d wit honboar d systems . Th e following analysi s wil l showtha t straigh t forward engineering solution s ar e availabl e fo r al l o f th e potentia l safet yproblem s whic hhav e bee n identified , an d tha t whil e fina l choice s regarding exac t systemdesign s li e wit hth e manufacturers , saf e fue l systemdesign s ar e achievabl e b yall . Thi s analysi s o f onboard safet yissue s an d th e associate d cos t an d leadtime generall yapplie s t o an ycanister-base d onboar d syste mdesign . Further , a s wil l b e discusse d below , thi s analysi s indicate s tha t i t i s quit e possibl e tha t overal l fue l syste msafet yimprovement s coul d accompan yth e implementatio n o f onboard controls . Th e importanc e o f evaluating th e safet yo f onboard system s i s highlighte d b

yth e Clea n Ai r Ac t (Sectio n 20 2 (a)(6) ) whic h direct s EPAt o consul t wit hth e Departmen t o f Transportatio n (DOT ) befor e requiring th e us e o f onboard vapo r recovery systems . Thi s requiremen t i s intende d t o insur e tha t al l safetyissue s hav e bee n properl yidentifie d an d addressed . Thi s repor t wil l als o hel p t o assis t i n th e fulfillmen t o f thi s requirement . A s outline d below , th e remainde r o f thi s repor t i s divide d int o fiv e sections . Th e firs t sectio n following thi s introductio n (Sectio n III) , provide s a genera l descriptio n o f a n onboard systemt o ai d i n th e understanding o f an yrelate d safet yissues . Sectio n I V summarize s an

d provide s EPA' s analysi s o f th e comment s receive d regarding th e desig n o f a saf e onboar d system , an d Sectio n V

discusse s onboar d effect s o n in-us e fue l systemsafety . Sectio n V I discusse s th e effect s safet yconsideration s hav e o n othe r importan t factor s suc ha s vehicl e cost s an d leadtime . Heavy-dut ygasoline-fuele d vehicle s (HDGV ) pos e simila r ye t distinc t onboar d contro l systemsafet yissues , an d Sectio n VI I addresse s thes e similaritie s an

d differences . Th e fina l sectio n provide s conclusions .P.1 1

• / * -9

- III . Onboar d Contro l SystemDescriptio n Befor e considering an ysafet yissues , i t i s importan t t o hav e a clea r understanding o f onboar d refueling vapo r recovery systems (onboard systems ) an d ho wthe ywork . Likewise , befor e considering th e characteristic s o f th e contro l system , i t i s importan t t o understand th e natur e o f refueling emissions . Th e purpos e o f thi s sectio n i s t o provid e th e reade r wit hbot ha clea r understanding o f wha t refueling emission s ar e an d how onboard system s operat e t o contro l thes e emissions . I n man yrespects , onboar d system s ar e simila r t o th e evaporativ e emissio n contro l system s no wi n us e o n mos t gasoline-powere d vehicles . I n fact , i t ha s bee n suggeste d tha t onboard system s ar e mor e a n extensio n o r modificatio n o f curren t evaporativ e emissio n system s than th e implementatio n o f a ne wcontro l technology . A n explanatio n o f th e difference s an d similaritie s betwee n th e two system s wil l provid e a bette r understanding o f th e incrementa l natur e o f onboar d system s relativ e t o curren t evaporativ e systems , an d wil l "b

e usefu l i n assessing th e design , cost , an d leadtime implication s o f implementing onboar d control s safely , whic har e t o b e discusse d late r i n th e report . Thi s sectio n wil l firs t briefl ydescrib e evaporativ e emission s an

d ho wthe yar e currentl ycontrolled . Next , refueling emission s wil l b e discusse d an d similaritie s betwee n onboar d system s an d curren t evaporativ e emissio n system s wil l b e presented . Th e sectio n wil l en d wit ha discussio n o f th e difference s betwee n th e two contro l systems . A . Evaporativ e Emission s Evaporativ e emission s emanat e fromtwo basi c sources : th e fue l tan

k an d th e fue l meterin g system(eithe r a carbureto r o r fue l injectors) . Evaporativ e emission s arising fro mth e fue l tan k ar e primaril y"diurnal " emission s whil e thos e fromth e fue l metering system ar e terme d "ho t soak " emissions. * Thi s analysi s i s primaril yconcerne d wit hfue l tank evaporativ e o r diurna l emission s sinc e thes e emission s ar e currentl y controlle d usin g an approac hsimila r t o tha t envisione d fo r an onboar d system . I t shoul d b e note d tha t a smal l amoun t o f ho t soak emission s come fro mth e fue l tank ; th e fue l tank evaporativ e contro l systemwoul d handl e thes e a s wel l a s th e diurna l emissions .P.1 2 -10

- Diurna l evaporativ e emission s consis t o f gaseou s hydrocarbon s tha t ar e displace d fro m th e tan

k whe n fue l i n th e tan k i s heated . Fue l heating ca n resul t fro m change s i n ambien t temperatur e o r during vehicl e operatio n du e t o th e vehicl e exhaus t systemand/o r recirculatio n o f fue l heate d b y the engine . I n eithe r case , a s fue l i n th e tan k an d vapo r above th e fue l hea t up , mor e o f th e liqui d fue l evaporates , an d th e vapo r itsel f expands , thu s causing hydrocarbo n vapo r t o b e released int o th e atmospher e (unles s capture d b ya contro l system) . Fue l volatility , siz e o f th e vapo r space , initia l tan k temperature , an

d th e degre e t o whic hth e tan k i s heate d can al l impac t th e quantit yo f hydrocarbon s emitted . Diurna l emission s occur o n a t leas t a dail ybasis , an d a system designe d t o contro l thes e emission s mus t b e capabl e o f handling , repeate d evaporativ e emissio n loads . Sinc e th e earl y1970's , mos t vehicle s hav e come equippe d wit ha contro l syste mt o limi t th e amoun t o f diurna l evaporativ e emissions . Th e nex t sectio n discusse s th e typ e o f contro l systemtypicall yuse d o n today' s vehicles . B . Evaporativ e Emissio n Contro l System Figur e 1 depict s a fue l tank equippe d wit han evaporativ e emissio n contro l system.[6 ] A s ca n b e see n fro mthi s figure , th e contro l systemi s relativel ysimpl e i n desig n an d require s veryfewcomponents . Th e purpos e o f thi s sectio n i s t o describ e eac ho f th e system' s component s i n term s o f bot h physica l appearanc e an d function . I n orde r t o effectivel ypreven t th e escap e o f fue l tank vapor s t o th e atmosphere , an evaporativ e contro l systemmus t perfor mthre e basi c functions . First , th e systemmus t limi t th e numbe r o f exit s throughwhic hfue l tank vapor s migh t escape . Second , th e exi t tha t doe s allo wfue l tank vapor s t o escap e mus t lea

d t o a containe r wher e th e vapor s ca n b e captured . Third , th e systemmus t eventuall yrestor e th e capacit yo f th e storag e containe r b ypurgin g i t o f th e trappe d vapors . Th e discussio n belo wdescribe s ho wan evaporativ e emissio n systemperform s thes e thre e functions . Th e firs t functio n a n evaporativ e emissio n systemmus t perfor mi s t o limi t th e outlet s throughwhic hvapor s can escape . A s ca n b e see n in Figur e 1 , ther e ar e onl ythre e opening s throughwhic hvapor s ca n pass : 1 ) th e fillpip e opening , 2 ) th e externa l vapo r ven t lin e t o th e fillpip e to p (abou t 1/2 " diameter) , an d 3 ) th e smal l limiting orific e (approximatel y0.050-0.05 5 inch ) i n th e to p o f th e tank . Th e fue l tank cap i s designe d t o for ma tigh t sea l wit hth e fillnec k s o tha t onc e the ca p i s secure d i n place , vapor s fro m th e fillpip e opening an d th e externa l ven t lin e ar e trappe d withi n th e system . Thus , onl yon e outle t exist s throughwhic h fue l tank vapor s can escape . Thi s singl e availabl e outle t i s th e smal l limiting orific e i n th e to p o f th e tank .PRESSURE/VACUU M RELIE F CA P -EXTRENA L VENT LIN E Figur e 1 Typica l Curren t Evaporativ e Syste m

LIMITINGORIFIC E

3/8 " DIA . 8 ' LONG VALVE

1 4 GALLO NFUE LTAN K # PURG EVALV E 

# xxyy-+ 3/8 " DIA

. T O PURG E

INDUCTIO N POIN T 1 LITE R CARBO N CANISTE RP.1 4 -12

- A s th e tan

k undergoe s temperatur e changes , an d hydrocarbo n vapor s ar e generated , pressur e build s u p i n th e tank (a s lon g a s th e fue l tan

k cap i s secur e i n place) . Thi s pressur e build-u p i s slowl yrelieve d a s ga s tank vapor s eventuall yforc e thei r waythroughth e onl yavailabl e exit : th e smal l limiting orific e i n th e top o f th e fue l tan k whic hlead s t o th e vapo r storag e devic e (charcoa l canister) . B ylimiting th e numbe r o f vapo r escap e passage s an d routing th e evaporativ e hydrocarbon s t o a singl e point , th e contro l systemha s successfull y performe d th e firs t o f it s thre e basi c functions . Befor e discussing th e evaporativ e emissio n system' s secon d function , i t i s importan t t o understand wh yth e orific e i n th e top o f th e tan k i s s o limite d i n size . Th e orific e i n th e top o f th e tan k i s verysmal l i n siz e fo r thre e reasons . First , i t allow s pressur e t o buil d u p in th e tan k whe n vapor s ar e generated . Thi s pressur e build-u p inhibit s furthe r evaporatio n an d create s . . a pressur e differentia l whic heventuall ylead s t o hydrocarbon. , vapo r being force d throughth e limiting orifice . Second , th e limiting orific e act s a s a liquid/vapo r separator . I f liqui d gasolin e wer e t o splas hu

p int o th e ven t line leading t o th e evaporativ e emissio n contro l storag e devic e (charcoa l canister) , damag e coul d potentiall yoccur t o th e storag e medi a (charcoal) . However , th e orific e i n th e top o f th e tan k i s s o smal l tha t liqui d passe s throughi t a t onl ya veryslowrate . Essentiall y onl yvapo r i s allowe d t o continu e t o th e canister . Thi s poin t lead s t o th e fina l reaso n fo r limiting th e siz e o f th e ven t orific e t o suc han extent . Wer e th e vehicl e eve r t o b e i n a rollove r accident , a verylittl e amoun t o f liqui d fue l woul d b e abl e t o leak from

th e tank throughsuc ha smal l orifice . Thus , th e limiting orific e i s size d larg e enought o allowfor adequat e escap e o f evaporativ e emissions , bu t i s smal l enough t o permi t onl ya slowleak fro mth e fue l tank i n th e cas e o f a vehicl e rollove r an d thu s provide s th e protectio n neede d t o compl ywit hFMVS S 301 . Th e cos t fo r thi s i s low . However , some manufacturer s incorporat e an additiona l valv e fo r adde d protection ; a

n exampl e i s show

n i n Figur e 2.[7 ] Storing th e evaporativ e hydrocarbon s i s th e secon d basi c functio n a

n evaporativ e emissio n system mus t perform . Onc e th e vapor s escap e fro mth e fue l tan

k throughth e smal l limiting orifice , theyprocee d througha ven t line (usuall yabou t l/4"-3/8 " insid e diamete r an d mad e o f some typ e o f flexibl e rubbe r compound ) tha t lead s t o a caniste r containing charcoal . Th e caniste r itsel f i s usuall ymad e o f plasti c an d i s generall y a cylindrica l or rectangula r container . Onc e insid e the canister , th e hydrocarbon s ar e adsorbe d ont o activate d charcoa l wher e the yar e store d temporarily .P.1 5 -13 - Figur e2

Th e tan k mounte d sprin g balance d floa tvalve i s a lo wcos tuni tdesigne d fo rventin g fue l tan k vapo rt o th e carbo n canister

. Th e devic e employ s a floa twhic h remain s ope n unde rnorma l conditions . Shoul d th e tan k leve l reac h a critica l height , th e floa twil l clos e th e caniste rven t line . I n th e even t o fextrem e vehicl e attitud e orroll-over , th e float wil l clos e th e caniste rvent line . Afiltere d tan k

mounte d sprin g balanced float valv e i s availabl e tha

t perform s th e sam e function s a s th e abov e sketches except th e tan k sid e o fth e par t i s filtere d to prevent contaminate s fro m enterin g th e par t whic h migh t effec t float closin g o fth e caniste rvent line . Fo rhig h flowapplication s tha t requir e a larg e volum e o

fvapo rventing , suc h as fue l in jectio n applications , a hig h flo wvalv e ha s bee n developed tha

t has mor

e tha n twic e th e presen t flowcapacitywithou t loosin g othe rcritica l performance parameters .



# FLOA TVALV E Borg-Warne rAutomotive , Inc . 70 7 Southsid e Or. , Decatur , Illinoi s 62525 Phone 217/42*463 1 

# 43 7 SKETC H NUMBE RP.1 6
•14

- Th e working capacit yo f th e charcoal , th e quantit yan d frequencyo f th e evaporativ e emissions , an d th e capabilit yo f th e syste

m t o restor e it s working capacit yal l affec t th e amoun t o f charcoa l required . Curren t passenge r ca r evaporativ e emissio n contro l system s typicall yutiliz e a 0.85-1. 5 lite r canister . [8 ] (Thi s siz e i s sufficien t fo r bot hdiurna l an d ho t soak evaporativ e emissions. ) However , a finit e amoun t o f charcoa l i s use d i n th e canister , s o th e storag e capabilit yo f th e caniste r i s limited . Onc e th e evaporativ e hydrocarbon s hav e bee n adsorbe d ont o th e charcoa l i n th e storag e canister , theywil l remai n ther e unti l removed . Th e hydrocarbon s mus t b e strippe d fro

mth e charcoa l periodicall yi n orde r t o restor e enoughworking capacit yt o adequatel ycaptur e eac hsuccessiv e evaporativ e emissio n load . Whil e th e vehicl e i s operated , th e evaporativ e emissio n syste mperform s it s third basi c functio n o f restoring th e storag e capabilit yo f th e charcoa l canister., . Afte r th e vehicle' s engin e i s running , manifol d vacuu mi s use d t o draw hydrocarbon-fre e ai r throughth e charcoa l canister . Hydrocarbon s store d i n th e caniste r ar e desorbe d int o th e ai r strea mwhic hflow s int o th e fue l metering systemvi a a flexibl e rubbe r purg e lin e o f abou t 3/8 " diameter . Onc e purged , th e evaporativ e hydrocarbon s ar e burne d a s fue l throughnorma l combustio n i n th e engine . Thi s proces s "empties " th e canister , thereb ypreparing i t fo r th e nex t evaporativ e emissio n load . On e aspec t o f th e purg e proces s whic hneed s t o b e mentione d bu t wil l no t b e explaine d i n grea t detai l i s th e fac t tha t th e caniste r i s no t continuousl ypurge d during vehicl e operation.[8,9 ] Avalv e locate d betwee n th e caniste r an d th e fue l metering systemi s opene d an d close d a t opportun e time s t o contro l th e purg e proces s an d limi t disturbance s whic haffec t engin e performanc e an d exhaus t emissions . T o summarize , th e curren t evaporativ e emissio n contro l system perform s thre e basi c functions : 1 ) i t limit s th e exit s throughwhic hfue l tank vapor s can escape ; 2 ) i t trap s th e vapor s i n a storag e device ; an d 3 ) i t restore s th e capacit yo f th e storag e devic e t o prepar e i t fo r th e nex t evaporativ e emissio n load . Onboar d system s ar e verysimila r t o evaporativ e emissio n contro l system s becaus e theymus t als o effectivel yperformth e same thre e basi c function s t o efficientl ycontro l refueling emissions . However , du e t o difference s i n th e quantit yo f vapor s an

d th e rat e o f generatio n o f evaporativ e an d refueling emissions , equipping vehicle s wit honboar d system s wil l requir e tha t some mino r modification s b e mad e t o curren t fue l an d evaporativ e emissio n contro l systems .-15

- Th e nex t sectio n provide s additiona l detai l regarding refueling emission s t o hel p explai n th e fue l an d evaporativ e syste mmodification s tha t woul d b e require d t o equi p vehicle s wit honboar d systems . C . Refueling Emission s Thre e processe s contribut e t o th e releas e o f hydrocarbon s during a refueling operation . Th e firs t two ar e collectivel y terme d displacemen t losses , th e third spillage . First , th e hydrocarbo n vapo r presen t i n th e tan k i s displace d fro mth e fue l tan

k b yliqui d fue l entering throughth e fillpipe . I f th e vehicl e fue l tan

k i s equippe d wit ha n externa l vapo r ven t lin e (a s show

n i n Figur e 1) , muc ho f th e fue l tank vapo r escape s vi a th e externa l ven t line whic hi s connecte d t o th e to p o f th e fillpipe . However , i f n o suc hvapo r passag e exists , th e vapo r make s it s wayou t throughth e fillpip e concurren t t o th e incoming liqui d fuel . Hydrocarbon s ar e als o generate d an d release d during refueling a s a resul t o f liqui d fue l evaporating a s i t i s dispense d int o th e tank . Thi s second typ e o f displacemen t los s i s cause d b yth e turbulenc e i n th e liquid/ai r interfac e durin g th e refueling proces s an d i s enhance d b

yth e highe r volatilit yo f th e dispense d fue l relativ e t o th e fue l i n th e tank . Athir d sourc e o f hydrocarbo n refueling emission s i s th e evaporatio n o f an y liqui d fue l spille d during th e refueling operation . O f th e thre e refueling emissio n sources , th e two displacemen t source s ar e generall ymuc hgreate r (b yfar) , unles s a larg e spil l occurs . Becaus e th e bul k o f refueling emissio n emanat e fromwithi n th e fue l system , refueling emission s ar e i n man yway s simila r t o diurna l evaporativ e emissions . Therefore , i t follow s tha t a n effectiv e onboar d systemca n b e designe d whic hutilize s th e same basi c technolog yan d approac hutilize d b ycurren t evaporativ e emissio n systems . I n fac t virtuall yal l onboar d system s considere d b ymanufacturer s i n thei r comment s incorporat e thi s approac ha s d o th e prototyp e system s develope d t o date.[10,11,12,13,14,15 ] Th e similaritie s betwee n onboar d an d evaporativ e emissio n system s ar e discusse d below . D . Onboar d Refueling Contro l System s 1 . Similaritie s wit hEvaporativ e Emissio n Contro l System s I n orde r t o contro l refueling emissions , onboar d system s mus t performth e same thre e basi c function s a s describe d previousl yfor diurna l evaporativ e emissio n systems . Thes e includ e limiting th e numbe r o f exit s throughwhic hrefuelin g vapor s ca n escape , storing refueling emission s temporaril yi n aP.1 8 -16

- charcoa l canister , an d purging th e charcoa l caniste r o f the stored refueling vapor s t o restor e it s capacit yprio r t o th e nex t refueling operation . Becaus e thes e thre e function s ar e s o similar t o th e thre e function s a diurna l evaporativ e emissio n contro l syste

mmus t perfor

man d th e emission s aris e fro mth e sam e location , extrapolatio n o f know n technolog

ylead s t o th e conclusio n tha t a

n onboard syste

mwoul d us e th e same approac h an d simila r hardwar e t o tha t whic hi s currentl yuse d t o contro l evaporative emissions . Figure s 3 an d 4 depic t two representative onboard system s an d a compariso n wit hFigur e 1 show s tha t onboard control s ar e verysimila r i n overal l design t o curren t diurna l evaporativ e emissio n contro l systems . However , whil e onboard system s do us e man yo f th e same basi c component s a s evaporativ e systems , (i.e. , charcoa l canisters , flexibl e rubbe r tubing , purg e contro l valve , etc.) , th e basi c difference s betwee n refueling an d evaporativ e emission s requir e a fewadditiona l components , an d a n enlargemen t o f certai n existing hardwar e i s require d for th e onboard system . Thes e ar e th e keydifference s betwee n th e two systems . Befor e discussing th e componen t addition s an d enlargements , a

n importan t aspec t o f th e onboar d refueling vapo r recoverysystemmus t b e introduced . Sinc e bot hemission s emanat e fro mth e same location , a properl ydesigne d onboard systemcoul d contro l bot hrefueling emission s an

d diurna l evaporativ e emissions . Thus , i f a n onboard refueling systemwer e incorporate d int o a vehicle' s fue l system , th e curren t diurna l evaporativ e emissio n contro l syste m woul d n o longe r b e needed . Thi s aspec t o f onboar d system s ha s severa l implications . First , i t reduce s th e conceive d degre e o f complexit yth e systemadd s t o th e vehicle' s fue l system . An entirel ynew , larger , mor e comple xsystem woul d no t b e neede d in additio n t o tha t whic hcurrentl y exists . Rather , th e curren t contro l systemwoul d b e modifie d t o b e somewha t large r wit ha smal l increas e i n th e numbe r o f components . Second , sinc e onboard system s ar e basicall y modifie d evaporativ e emissio n systems , man yo f th e safet y design concern s associate d wit honboar d system s hav e alread y bee n addresse d i n curren t evaporativ e emissio n contro l system designs . Thes e approache s coul d als o b e use d i n th e integrate d system . On e fina l effec t a "dua l function " contro l systemha s i s i t require s les s "packaging " spac e an d i s les s expensiv e t o produc e than two separat e systems .Figur e 3 integrate d Evaporatiye/Refuelin g Syste m

Nozzl e Actuate d Valv e Fron t Mounte d Caniste r Mechanica l Sea l

I
—PRESSURE/VACUU

M RELIE F CA P NOZZL E ACTUATE D ROLLOVER/VENT VALVE

MECHANICAL SEA L 

# r 5/8 " DIA . 8 ' LONG 

# V05 " DIA . LIMITINGORIFIC E FLOAT/ROLLOVE R VALV E

1 4 GALLO NFUE L TANK PURG E VALV E

3 LITE R CARBON CANISTE R I

T O PURG E INDUCTION POIN T

T J C OFigur e 4 Integrate d Evaporative/Refuelin g System

Tan k Mounte d Valve s Rea r Mounte d Caniste r J-Tub e Sea l 

# r NOZZL E ACTUATE D ROLLOVER/VENT VALV E 5/8 " DIA . 3 ' LON G PURG E VALV E 3/8 " DIA . 5 ' LON G | fU J l^VA ] 

## •fh—^iXy—fT O PURG E INDUCTIO N POIN T

3 LITE R CARBO N CANISTE R

1 4 GALLONFUE L TANK

oP.2 1 -19

- 2 . Additions/Modification s t o Evaporativ e Emissio n Contro l Systems . Th e difference s betwee n onboard system s an d curren t diurna l evaporativ e emissio n contro l system s ca n b e separate d int o two broad categories : 1 ) thos e relate d t o th e sealing o f th e system , an

d 2 ) thos e relate d t o th e magnitud e an d frequenc y o f th e refueling emissions . Becaus e o f thes e differences , onboard system s requir e severa l additiona l components , an d severa l component s o f th e curren t evaporativ e systemmus t b e increased i n siz e or slightl ymodified . a . Addition s t o th e Presen t System Diurna l evaporativ e emissio n contro l system s limi t th e numbe r o f vapo r exit s b yusing a fue l tan k cap t o clos e of f th e fillneck . However , during a refueling operation , th e fue l tank ca p i s no t i n place , an d consequently , onboar d .-system s mus t rel yo n some othe r typ e o f sealing mechanis mt o .preven t th e escap e o f vapo r throughth e fillnec k opening . Currently , tw o type s o f fillnec k seal s ar e availabl e fo r us e o n onboar d system s —liqui d an d mechanical . Liqui d fillnec k seal s utiliz e modifie d fillpip e design s t o rout e incoming gasolin e i n suc ha waytha t a colum n o f gasolin e i s forme d whic hprohibit s th e vapor s i n th e fue l tank from escaping t o th e atmospher e vi a th e fillneck . Whil e thi s ma y soun d somewha t complicate d a t first , th e concep t i s fairl yeas y t o understand wit hth e hel p o f a drawing . Severa l liqui d sea l configuration s hav e bee n developed , bu t on e desig n whic hha s bee n show

n t o b e particularl yattractiv e frombot ha desig n an d cos t perspectiv e i s th e "J-tube " (show n i n Figur e 5).[16 ] A s fue l i s dispense d int o th e fillneck , i t i s force d t o pas s throughth e "U " shape d portio n o f th e fillpipe . Aliqui d trap i s forme d i n th e "U " shape d portio n o f th e fillpip e whic h prevent s vapor s fro mescaping vi a th e fillneck . Th e "J-tube " extensio n coul d b e mad e o f metal , plasti c or har d rubber . Anothe r typ e o f fillnec k sea l whic hha s bee n show n t o b e effectiv e i s th e mechanica l typ e seal . [14,15 ] Th e mechanica l typ e sea l (se e Figur e 6 ) i s basicall ya n elastomeri c devic e whic hform s a clos e connectio n wit hth e inserte d fue l nozzl e an d thereb

yeliminate s an

yspac e i n th e fillnec k opening throughwhic hvapo r coul d escape . Whil e bot hth e liqui d an d mechanica l typ e seal s performth e same basi c functio n o f limiting th e availabl e vapo r exits , th e liqui d typ e sea l i s inherentl ya simple r design .P.2 2 -20 - Figur e5

J-Tub eLiqui dSea l

"-TUB E T O CANISTS RP.2 3 -21 - Figur e 6 Mechanica l Sea l 

## FE L PIP E MOOffTCATIONS ROTAR YSEA L ROTAR

YSEA L 1 TRAPDOO

R ^_-^J l ijUS^^A

^r \ ^^"GUD E 1 LEA D RESTRICTO R



## FIL LPIP E MODIFICATION S ROTAR YSEA L

.

ROTAP YSEA L TRAPDOO R l l "

LEA O RESTRICTO R ^ SPOU T

^—SPOU T

- -

-

-

•P.2 4
-22

- I f a mechanica l typ e sea l wer e used , excessiv e pressur e coul d buil d i n th e fue l tank i f th e fue l nozzl e automati c shu t of f mechanis mfailed , or i f fo r some unusua l reaso n th e vapo r line leading t o th e charcoa l caniste r became blocked . T o avoi d th e possibilit yo f a fue l spitbac k Whic hcoul d b e cause d b y thi s overpressure , a simpl e pressur e relie f devic e woul d b e needed . Mor e detai l o n thi s devic e wil l b e provide d i n Sectio n IV . Therefore , eithe r typ e o f sealing mechanis m- liqui d or mechanica l - can b e use d t o preven t th e escap e o f refueling vapor s t o th e atmospher e vi a th e fillneck . Bot hsealing approache s hav e bee n teste d an d provid e simila r contro l efficiencies.[14,15 ] b . Modification s t o th e Presen t System Th e difference s i n th e frequency , magnitude,.-an d rat e o f generatio n o f refueling an d diurna l evaporativ e emission s lead s t o th e nee d fo r severa l modification s t o th e presen t evaporativ e system . Eac ho f thes e i s discusse d below . (1 ) Charcoa l Caniste r Siz e Generall yspeaking , o n a pe r even t basis , refueling emission s ar e produce d les s frequentl ybu t ar e large r i n magnitud e than diurna l evaporativ e emissions . Consequently , mor e hydrocarbo n storag e capacit y(large r charcoa l canister ) i s neede d t o contro l refueling emission s tha n i s neede d fo r evaporativ e emissions . Fo r an ygive n vehicle , th e siz e o f th e caniste r neede d depend s primaril yo n th e fue l tan k volume an

d th e refueling emissio n rate . Th e refueling emissio n rat e i s chiefl ya functio n o f th e fue l volatilit y(RVP) , dispense d fue l temperature , an

d th e temperatur e o f th e fue l i n th e vehicle' s tan k prio r t o refill . Fo r caniste r desig n purpose s th e temperature s an

d fue l volatilit yspecifie d i n EPA' s draf t refueling emissio n tes t procedur e woul d b e use d t o determin e th e desig n emissio n rat e whic hth e caniste r woul d nee d t o b e abl e t o capture . Caniste r sizing woul d the n b e a functio n o f tan k volume , th e design emissio n rate , a s wel l a s consideration s fo r safet yan d deterioratio n factor s t o assur e an adequat e workin g capacit yove r th e lif e o f th e vehicle . Th e siz e o f th e caniste r neede d fo r an integrate d refueling/evaporativ e contro l systemcanno t b e state d categoricall ysinc e ther e ar e severa l othe r variable s whic h mus t b e considere d suc ha s purg e rate , charcoa l workin g capacity , an

d caniste r geometry . However , o n averag e i t i s expecte d tha t a caniste r fo r an integrate d refueling/evaporativ e system woul d b e approximatel y3 time s a s larg e a s th e on e use d for th e presen t evaporativ e system . [17 ]P.2 5 -23

- Whil e th e large r caniste r doe s no t presen t an ytechnica l problems i t maycaus e packaging problem s o n a fewsmalle r vehicl e model s whic hcoul d lea d t o canister s bein g place d i n location s othe r than unde r th e vehicl e hood . Whil e virtuall y al l evaporativ e emissio n systemcanister s ar e no wlocate d unde r th e vehicl e hoo d ther e i s nothing inheren t i n th e desig n o f a n onboard systemwhic hrequire s tha t canister s fo r integrate d systems als o b e locate d there . I n fact , ther e mayb e some cos t advantag e t o locating th e caniste r nea r th e fue l tank sinc e th e amoun t o f large r vapo r line s can b e minimized . I t i s expecte d tha t manufacturer s woul d plac e canister s i n a locatio n whic h provide s th e optimu mmi xo f safety , cost , an d performanc e characteristics . (2 ) Refueling Ven t Lin e Modification s Also , i n orde r t o accommodat e th e highe r vapo r flowrate s associate d wit hrefueling emissions , a large r vent.lin e betwee n th e fue l tank an

d charcoa l caniste r i s neede d 'alon g wit ha large r opening in th e top o f th e fue l tan k t o accommodat e th e large r ven t line . Th e curren t ven t line t o th e caniste r associate d wit hth e evaporativ e systemi s abou t 3/ 8 inch . Th e ven t lin e wit hth e integrate d evaporative/refueling system woul d b e approximatel y1/ 2 - 5/ 8 inchi n diameter. [ 16 ] Th e large r ven t lin e (an d large r opening i n th e to p o f th e fue l tank ) introduc e a fewadde d complexities . Unlik e th e limiting orific e use d i n evaporativ e emissio n systems , th e large r opening require d fo r an onboar d system canno t provid e liquid/vapo r separatio n o r rollove r protection . Consequently , additiona l device s ar e require d o n an onboar d systemt o mee t thes e needs . Th e liquid/vapo r separator , example s o f whic har e show n i n Figure s 7 an d 8 , i s simpl e i n design an

d purpose.[14,18 ] I t act s t o remov e gasolin e droplet s fro mth e vapo r strea

man d return s th e liqui d t o th e fue l tank t o preven t liqui d gasolin e fro mentering th e charcoa l canister . Man

ydesign approache s ar e availabl e i n additio n t o thos e show

n here . Th e separato r itsel f mayb e a distinc t component , or it s functio n mayb e buil t int o anothe r componen t suc ha s show

n late r i n Figur e 21 . I n term s o f rollove r protection , severa l simpl e device s ar e availabl e whic hca n preven t fue l spill s during a n accident , an

d als o provid e th e benefit s o f a limiting orific e describe d above . Thes e wil l b e discusse d i n mor e detai l i n Sectio n I V o f thi s documen t sinc e rollove r an

d acciden t protectio n fo r th e fue l systemi s primaril ya safet yissue . Asid e fro

mth e difference s discusse d above , onboar d an d evaporativ e emissio n contro l system s ar e ver ysimila r i n design . The ybot hac t t o direct , trap , an d consum e hydrocarbo n vapor . Onboar d system s requir e onl ya fe wadditiona l components , an

d becaus e the ycoul d b e integrate d int o vehicl e fue l system s t o handl e bot hrefueling an d evaporativ eP.2 6 -24

- Figur e7 

### VAPOR-LIQUI D SEPARATO R

Mountin g Hole s

FloatWeigh tFigur e8

VAPOR OU T

ADHESIV E SEA L

.7 5 HOS E TY R VAPOR/UGU D I N

UQUO/OOKOENSAT E RETUR N Cl UQU D REUE F SLOT 

## E __1. 1

_ . ->.— i y'/

2..0 _ i 

# ~Q~l.- i U l I

MOUNTIN Q TABS <3

)

A R OPE N CEL L FOA M AR MES H FABRI C NYLO N UPPE R »40USl» M PLASTI C 

# S LOWE R HOUMN a FLA6TIC W Macattwo * MMaauu . apcow. VAPO R - LIQUI D SEPARATO R MU«LL« R AliOCIATIl . IM C tttthlOW . M P **f«ti/i5/JaJ•<•*« ' FUL L | JmtM|« » rP.2 8
-26

- emissions , overal l contro l systemcomplexit yi s no t increase d significantly . Also , becaus e o f th e integratio n o f th e refueling/evaporativ e emissio n contro l functions , i t shoul d b e apparen t tha t man yo f th e safet yconcern s associate d wit h onboard system s hav e alread ybee n considere d i n design s o f th e presen t evaporativ e emissio n systems . Th e experienc e an d knowledg e gaine d in implementing saf e evaporativ e emissio n system s provide s a substantia l bas e o f informatio n t o us e i n designing an

d developing saf e integrate d evaporative/refueling systems . 3 . Volatilit yEffect s A s wa s mentione d above , th e refueling emissio n rat e i s a keyfacto r i n th e siz e o f th e onboar d systemcanister , an d th e refueling emissio n rat e itsel f varie s wit hth e fue l volatilit y an d th e dispense d an d fue l tan

k temperatures . Fo r desig n purposes , th e caniste r woul d b e size d base d o n th e volatilit y an d temperatur e specification s prescribe d i n EPA. ' s refueling emission s tes t procedure . Th e parameter s prescribe d i n EPA' s procedur e ar e base d o n nea r wors t cas e summe r seaso n conditions , s o th e onboar d caniste r woul d hav e capacit yt o achiev e contro l unde r virtuall yal l summe r conditions . However , a s averag e temperature s decreas e i n th e winter , RV P level s increas e an d dispense d an

d fue l tank temperature s decrease.[19 ] Th e questio n arise s a s t o whethe r th e onboar d caniste r woul d hav e adequat e capacit yt o captur e winte r emission s wit hhighe r RVP fuels . I f th e capacit yi s inadequat e caniste r breakthroughmayoccur an d some emission s ma yb e uncontrolled . Previou s studie s an d analyse s conducte d b yEP Aan

d other s hav e show

n tha t th e refueling emissio n rat e increase s wit hth e fue l volatilit y(RVP ) an d fue l tank temperatur e an d decrease s wit hth e dispense d fue l temperature.[19 ] On e stud y(CAP E 9 ) use d volatilitie s an d temperature s typica l o f winte r conditions.[20 ] Using winte r seaso n fue l volatilitie s an d temperature s i n th e relationshi p derive d fro mthi s stud

yyield s winte r refueling emissio n rate s les s tha n th e desig n load emissio n rat e fo r th e caniste r dictate d b yth e refueling emission s tes t procedure . Winte r seaso n value s (De c - Feb ) rang e fro

m5. 1 t o 5. 9 g/ga l fo r th e norther n state s wher e RVP s ar e quit e high(14-1 5 psi ) whil e th e design loa d valu e i s 7.2 5 g/gal . Thu s winte r emission s woul d b e controlle d a s well . EPAi s presentl yconsidering a program t o contro l th e volatilit yleve l (RVP ) o f in-us e fuel s durin g th e summe r month s (mid-Ma yt o mid-September) . A s par t o f tha t program , in-us e volatilit ylevel s nationwid e woul d b e limite d t o level s abou t 21. 7 percen t les s than th e curren t ASTMleve l fo r tha t are a during th e affecte d months . I f tha t programwa s enacted , th e volatilit yo f th e fue l for refueling emission s testing woul d b eP.2 9 -27

-

se t a t 9. 0 ps i RVP , th e design loa d emissio n rat e fo r th e caniste r coul d dro p t o 6. 0 g/gal , an d onboard canister s coul d b e somewha t smaller . However , a s can b e see n fromcompariso n wit hth e emissio n rat e figure s presente d above , winte r emission s woul d stil l b e controlled . Whil e no t th e primarymotivator , in-us e volatilit ycontro l mayhav e some attendan t safet ybenefits . Lowe r RVP fuel s generat e les s vapo r an d thu s coul d b e considere d somewha t safe r i n a genera l sense . Mor e specifically , lowe r volatilit yfuel s generat e les s fue l tan k evaporativ e emission s an d thu s coul d reduc e fue l tan

k pressurizatio n problem s whic hoccu r o n some vehicle s wit hdamage d or altere d evaporativ e emissio n system s (e.g . non-standar d ga s caps ) operating unde r extremel yatypica l conditions . Thi s pressurizatio n coul d lea d t o some fuel/vapo r being release d fro mth e fillpip e whe n th e ga s cap i s removed , especiall yi f th e fue l tank wa s relativel yful l a t th e time . Lowe r vapo r pressur e fue l woul d reduc e the . degre e o f pressurizatio n whic hcoul d occur unde r thes e circumstance s an d thu s reduc e o r eliminat e th e spillag e whic hma yresult . Thu s th e safet yo f refueling operation s woul d b e improved . IV . Desig n Consideration s fo r a Saf e System A s wa s discusse d previously , severa l commenter s hav e expresse d concer n regarding th e potentia l safet yimplication s o f onboar d systems . Arevie wo f thes e comment s indicate s tha t thes e concern s fal l int o two broad areas : th e desig n o f a saf e onboard systeman d effect s o n in-us e fue l systemsafety . Concern s i n th e firs t are a wil l b e addresse d i n thi s section . Th e sectio n whic hfollow s (Section V ) wil l addres s th e late r are a o f concern . Comment s receive d regarding th e design o f a saf e onboar d systemfal l i n thre e categories : 1 ) safet ytes t design , requirements , 2 ) safet yeffect s o f maintenance , defects , tampering an

d repairs , an

d 3 ) refueling operatio n safety . EPA' s summaryan

d analysi s o f th e comment s i n eac hcategoryi s presente d below . A . Safet yTes t Desig n Requirement s 1 . Introductio n Befor e analyzing th e safet ytes t design requirement s i t i s interesting t o look a t fue l systemsafet yfro man in-us e perspectiv e for passenge r car s meeting FMVS S 301 . Presently , abou t 1. 6 percen t o f al l accident s involve a vehicl e rollove r o f some typ e an

d abou t 0. 5 percen t o f th e rollove r accident s resul t i n a fire . [21 ] Thi s result s i n a fir e rat e o f 0.00 8 percent . Thus , neithe r rollove r accident s o r subsequen t fire s ar e common . Similarly , 0.1 4 percen t o f al l fron t an d rea r en

dP.3 0 -28

- collision s lea

d t o a vehicl e fire.[21 ] Althoughvehicl e cras h fire s ar e seemingl yuncommon , approximatel y160 0 fatalitie s resul t eac hyea r fro mthes e fires.[22 ] Thus , fro man in-us e perspective , vehicl e cras hfire s ar e unusua l bu t seriou s events . On e o f th e mos t effectiv e way s t o protec t agains t vehicl e cras hfire s i s t o restric t fue l leakag e during accident s b y insurin g th e overal l integrit yo f th e vehicle' s fue l system . T o insur e fue l systemintegrit yduring a crash , al l currentl y manufacture d passenge r car s an d light-dut ytruck' s wit ha Gros s Vehicl e Weigh t Rating (GVWR ) o f 10,00 0 lbs or less , mus t compl y wit hFedera l Moto r Vehicl e Safet yStandard (FMVSS ) 301.[23 ] Basically , FMVS S 30 1 require s a vehicl e t o restric t fue l leakag e t o les s than on e ounc e pe r minut e whe n subjecte d t o a rollove r tes t following fron t an d rear collision s a t 3 0 mile s pe r hour (mph) , an d sid e collision(s ) a t 2 0 mph . I n a rollove r test , a vehicl e i s turne d o n eac ho f it s side s an d completel y upsid e dow

n an d hel d in eac ho f thes e thre e position s fo r a perio d o f five minutes . Onboar d systemdesign s mus t tak e int o accoun t an

d protec t agains t fue l leakag e or othe r fir e hazard s whic hcoul d occur i n FMVS S 30 1 testing . Along thes e lines , two issue s exis t regarding th e desig n o f a n onboard systemcapabl e o f passing FMVS S 301 . Thes e includ e rollove r protectio n an d th e crashworthines s o f key onboard systemcomponent s an d connections . A s wa s discusse d previously , onboar d system s requir e th e us e o f a somewha t large r ven t lin e (abou t l/2"-5/8 " diamete r a s compare d t o l/4"-3/8 " o n curren t vehicles ) betwee n th e fue l tank an d charcoa l canister , an d a simila r size d orific e woul d exis t i n th e fue l tank . Whil e th e externa l ven t lin e use d o n many curren t fue l tank s als o require s a 1/2 " orifice , manufacturers ' onboard system

design s mayincorporat e a rollove r protectio n devic e t o protec t agains t fue l leakag e durin g an FMVS S 30 1 rollove r tes t eve n thoughpresen t design s d o not . Also , vehicl e crashe s presen t th e possibilit yo f direc t or indirec t damag e t o fue l systemcomponents . I n some case s thi s damag e coul d lea

d t o a fue l lea

k or increas e th e potentia l fo r a vehicl e fir e i n some othe r portio n o f th e fue l system . Thu s a properl ydesigne d onboar d systemmus t no t compromis e th e crashworthines s o f th e systeman d keycomponents . 2 . Rollove r Protectio n Arollove r protectio n devic e i s basicall ya valv e tha t woul d clos e of f th e refueling ven t lin e wheneve r th e ris k o f fue l leakag e existed . Severa l rollove r protectio n design s hav e bee n propose d b

yaut o manufacturer s an d othe r interest s whic h coul d adequatel yperformthi s safet yfunction . Severa l o f thes e ar e discusse d below .P.3 1 -29

- On e design whic hha s bee n propose d b ysevera l source s can b e terme d th e nozzl e actuate d valve . Th e valv e i s integra l t o th e fillpip e an

d i s locate d nea r th e top o f th e fillpipe , perhap s nea r th e leade d fue l restrictor . Durin g refueling , th e valv e i s opene d b

yth e insertio n of . a fue l nozzle . Wit hth e valv e open , a clea r passag e throughth e ven t lin e i s availabl e t o allowfo r th e routing o f refueling vapor s t o th e charcoa l canister . Othe r than during refueling , th e valv e remain s close d an

d effectivel yeliminate s th e potentia l fo r fue l leakag e throughth e refueling ven t line durin g a rollove r accident . Figure s 9 thorough1 5 showfiv e differen t nozzl e actuate d valv e assemblie s capabl e o f performing th e rollove r protectio n function.[13,15,18,24 ] Figure s 9 through1 3 als o demonstrat e ho wnozzl e insertio n woul d ope n th e valv e t o provid e a larg e orific e fo r th e venting o f fue l tank vapor s during refueling an d whe n th e nozzl e i s remove d th e ven t line woul d b e closed . Also , whil e a rollove r protectio n device , migh t b e necessary , i t i s interesting t o not e tha t man ycurren t productio n passenge r car an d light truc k model s (mostl ysid e fill ) employa

n externa l vapo r ven t line o f abou t 1/2 " diamete r tha t connect s th e fue l tank t o th e top o f th e fillpip e (se e Figur e 1) . Thi s externa l ven t line i s approaching th e siz e neede d fo r a refueling ven t line , an d ye t manufacturer s hav e include d thes e externa l ven t line s withou t an yrollove r protectio n device . A s wil l b e discusse d below , dependin g o n th e desig n used , a rollove r protectio n systemmayactuall y enhanc e safet yove r curren t designs . Thi s analysi s ha s presente d severa l basi c rollove r valv e design s capabl e o f providin g th e protectio n require d b yFMVS S 30 1 tests . Manufacturer s coul d choos e t o implemen t on e o f thes e approaches , o r coul d develo p another . Th e approac h ultimatel yselecte d wil l b e tha t whic hprovide s cos t efficien t protection , i s compatibl e wit hth e othe r component s o f th e manufacturer s onboar d system , an d can b e integrate d effectivel y int o th e vehicl e desig n fro m bot hsafet yan

d operationa l perspectives . 3 . Component/SystemCrashworthines s Th e second issu e regarding safet ytes t desig n requirement s involve s th e crashworthines s o f th e keycomponent s o f an onboar d system . Thi s include s thos e component s mos t susceptibl e t o damag e i n an acciden t (nozzl e actuate d rollove r valve , charcoa l canister ) an d th e structura l integrit yo f th e vapo r lin e (an

d connections ) whic hmayexis t betwee n th e to p o f th e fue l tan

k an d th e rollove r valve . Aproblemi n on e o f thes e thre e area s coul d caus e a vehicl e t o fai l FMVS S 30 1 test s an d mus t b e addresse d i n prope r systemdesign . Eac ho f thes e concern s i s discusse d below .Figur e9 

## SEALE D FILLE R NEC KSYSTE M TAN KVEN TVALV E ASSEMBL Y IDURIN G NORMA L VENICL E OPERATION ) T O CANISTE R - LIQUI D STO P

SHUT-OF F VALV E

LEADE O FUE L DEFLECTO R GA S CA P

OVERFIL L RELIE F VALV E i C O o IFigur e1 0 

## SEALE D FILLE R NEC KSYSTE M TAN KVEN TVALV E ASSEMBL Y (DURIN G REFUEUN O EVENT )

T O CANISTE R ~ LtOUi U STO P LEADE D FUE L OEFLECTO R

L O M I

OVERFIL L RELIE F VALV E

SEA L FUE L NOZZL EFigur e1 1 

## LIQUI D SEA L SYSTE M TAN KVEN TVALV E ASSEMBL Y IDURIN G NORMA L VENICL E OPERATION !

TO CANISTE R - SHU TOF F VALVE

LEADE D FUE L DEFLECTO R CA S CA P I CO t o IFigur e1 2 

## LIQUI D SEA L SYSTE M TAN KVEN TVALV E ASSEMBL Y IDURIN G REFUEUN O EVENT )

T O CANISTE R -

VAPO R FRO M TAN K SHUTOF F VALV E LEADE D FUE L

OEELECTO R

FUE L HQZ2LE I c o coFigur e1 3



### NOZZLE-ACTUATE D REFUEUN G EMISSION S VAPO R VEN TVALV E

Vapo rt o Caniste r Vapo rfro m

Vapor/Liqui d Separato r

i C O I

T l

C O 0 )Figur e1 4

NOTES : 1 . REMOV E AL L BURR S < SHAR P E06ti . 2 . NYLO N PART S MA YB E FABRICAT E O FRO*v \ PLASTI C COMPATIBL E W/OA&OUN E \ METHANO L % AI L DIMENSION * NO TSHOWN .

—.06TV»r AL L OVE R I O I RIVE TWASHE R FVAT E S . STEEL .

V w r RWE T

CA M SPACE R CA M P»I 4 LAMIMATK D - FLAPPE R ' CA M FOLLOWER C A M FLOA TBAL L UPPE R VALV C MbN< « LOWE R VALVE . HV44 . 0«*CIU » HO N ft. 61XEL . ALUM . 3T . MEE L IUM A OM&lSCt NYLO M ALUM . MYLO M NYLO N MYLO N 31 6

3t* > fcOfcl-Ttfc 31 4

feOM-Tb

l i m \ REFUELIN G VAPO R VEN TVALV E

ASSEMBL Y UU«LL« H ASSOCIATE^ , w c iiin«w« . M O :*t a 

# 'M "AV» H SCALE : ruuJ | jr*a « | o > I .

c

o ^ iP.3 8 -36

- Figur e1 5

"ToyotaConcept "



## Rubbe rSea l Valv e\ t o Caniste r\ )( fro mFue l >

vh/yfyf

A 

# Tan kV^W^X / 

# A / t o Fue l Tan

k Refuelin g

/ Nozzl eP.3 9
-37

- However , befor e beginning thes e discussions , i t shoul d b e note d tha t component/systemcrashworthines s i s no t a t al l a ne w concern . Manufacturer s mus t addres s thes e same concern s i n th e design o f th e curren t evaporativ e emissio n systems . Give n th e similarit yo f onboard refueling an d evaporativ e controls , an d tha t man

ysystem s wil l b e integrated , ther e shoul d b e n o ne wo r uniqu e problem s i n thi s area . a . Rollove r Valv e First , th e crashworthines s o f th e rollove r protectio n devic e i s a design consideratio n for nozzl e actuate d valves , sinc e the ywoul d b e locate d nea r th e exterio r shel l o f th e vehicle . Integratio n o f nozzl e actuate d valve s int o th e overal l vehicl e design woul d hav e t o includ e a consideratio n o f th e potentia l t o sustai n damag e i f struc k in a collision . However , thi s design consideratio n i s straightforward , an d i t i s reasonabl e t o expec t tha t manufacturer s can an d wil l integrat e rollove r valve s int o thei r fillpip e design s withou t decreasing th e structura l integrit yo f th e fillpip e whil e providing crashworthines s for th e valve . Fo r example , i t i s wort hnoting tha t vehicl e manufacturer s hav e deal t wit hsimila r problem s i n thei r design s o f fillpipes , externa l vapo r ven t lines , an

d ga s caps , an

d i n fact , on e woul d no t expec t th e nozzl e actuate d rollove r valv e t o b e an ymor e susceptibl e t o damag e than thes e components . A s wa s mentione d previously , th e 1/2 " externa l ven t line lie s i n thi s same are a o n th e vehicle , an d ye t manufacturer s hav e include d suc hven t line s withou t a rollove r protectio n device . b . Vapo r Lin e Similarly , manufacturer s wil l hav e t o b e cognizan t o f th e structura l integrit yo f th e vapo r lin e an d vapo r lin e connections , i f any , betwee n th e fue l tan k an d th e rollove r valve . Thes e woul d hav e t o b e designe d t o withstand th e stresse s whic hmigh t occur i n a cras hi n orde r t o maintai n fue l systemintegrity . However , ther e i s n o significan t engineering challeng e t o accomplishing thi s objective . Th e integrit yo f thi s portio n o f th e vehicle' s vapo r lin e can b e assure d throughus e o f a vapo r line materia l o f prope r strength , flexibility , an d durability . Anumbe r o f vapo r line s o f differen t material , wal l thickness , an d constructio n ar e currentl yavailable . I n addition , routing o f thi s portio n o f vapo r lin e i s anothe r desig n paramete r availabl e t o manufacturers . A s a matte r o f course , manufacturer s ar e expecte d t o insur e tha t th e line i s protecte d fro m abrasio n an

d norma l wea r an

d tha t i t i s no t i n a vulnerabl e locatio n i n th e even t o f a collision . Thi s i s considere d straightforwar d give n tha t o n integrate d system s th e refueling vapo r lin e no w replace s tha t use d fo r contro l o f diurna l evaporativ eP.4 0 -38

- emissions . Simila r routing s woul d b e expected . Vapo r lin e integrityan

d connection s in curren t vehicle s mus t mee t simila r requirements , an

d i t i s reasonabl e t o expec t tha t simila r material s an

d connecting approache s woul d b e used . Finall ywit hregard t o vapo r line integrit yan d connections , i t i s wort hnoting tha t man yvehicl e model s no w us e a flexibl e inser t betwee n th e fillpip e an d fue l tan

k t o enhanc e th e fue l syste msafet yin-us e (se e Figur e 16).[15 ] Similarly , i n man yvehicl e model s th e externa l ven t lin e actuall yincorporate s a flexibl e vapo r line whic hconnect s th e meta l portion s o f the externa l ven t line fro mth e to p o f th e fue l fillpip e an

d th e fue l tan

k (se e Figur e 16) . Thes e connection s ar e subjec t t o th e same performanc e requirement s a s woul d b e neede d for onboard syste m vapo r line s an

d in some case s ar e eve n mor e critica l an d demanding . Evidenc e i s tha t thes e hav e bee n incorporate d safely . Th e manufacturers ' experienc e wit hcurren t vehicl e evaporativ e an d ..fuel system s describe d above demonstrate s tha t vapo r lin e and . vapo r lin e connection s can b e mad e t o withstand th e stresse s whic hoccu r i n a vehicl e accident . c . Charcoa l Caniste r Concern s regarding th e crashworthines s o f th e charcoa l caniste r cente r o n th e possibilit ytha t a caniste r rupture d i n a n acciden t coul d presen t a fir e hazar d i f an ignitio n sourc e exist s nearby . Eve n i f th e ruptur e o f th e integrate d refueling / evaporativ e caniste r occurre d i n some cases , th e potentia l hazard shoul d no t b e overstated . Whil e carbo n canister s d o contai n gasolin e vapor , theyar e strongl yadsorbe d t o activ e site s withi n th e carbo n be d an d no t easil yrelease d t o th e atmosphere . Thus , eve n i f a caniste r wer e crushe d an d it s content s dumped , gasolin e vapo r woul d no t b e presen t i n th e atmospher e i n sufficien t quantit yt o b e flammable . Ther e i s n o availabl e evidenc e o f "caniste r fires " i n an yaccident s involving vehicle s wit hevaporativ e systems . Th e fac t tha t onboard canister s woul d b e large r an d woul d hol d mor e vapor s initiall ytha n curren t evaporativ e system s make s n o difference . Whil e th e refueling loa d t o th e caniste r i s large r than th e evaporativ e load , afte r th e firs t fewmile s o f drivin g th e caniste r woul d b e purge d suc htha t th e amoun t o f vapo r remaining i n th e caniste r i s essentiall yth e same a s tha t presen t i n curren t evaporativ e emissio n canister s alone. * Th e Du e t o th e natur e o f th e charcoa l use d t o trap hydrocarbo n vapors , an

d stric t certificatio n tes t requirements , hydrocarbon s woul d b e quickl ystrippe d from th e charcoa l earl yi n th e purg e process . Therefore , durin g mos t o f th e operatio n o f th e vehicl e (9 0 percent) , th e charcoa l caniste r doe s no t contai n enoughhydrocarbo n vapo r t o presen t an

ysafet yrisks.[9 ]Figur e1 6



### BUIC KCENTUR YFUE L TAN K AN D FILLPIP E PRODUCTIO N CONFIGURATIO N

Fue l Sendin g Uni t an d Ven t Orific e Nozzl e Spou t

12«/

2 " i

u > <x > I

T

JP.4 2
-40

- lack o f ris k fro

mcharcoa l canister s i s supporte d b ya recen t submission fro

mNissa n t o EPA , stating tha t n o safet yproblem s woul d b e expecte d wit hrefueling canisters.[25 ] Thu s i t coul d b e argued tha t th e hazard , i f any , i s no t significantl y differen t than tha t no wfoun d o n presen t systems . Thus , i t i s hard t o perceiv e an yadde d ris k fro

mth e us e o f a large r charcoa l canister . Nevertheless , i f a manufacture r believe d tha t th e caniste r pose d a potentia l risk , the ris k coul d b e eliminate d through placemen t o f th e caniste r i n a protecte d are a suc ha s th e rea r o f th e engin e compartmen t or i n some underbod yare a a s ha s bee n suggested b

ysome manufacturers.[12,13 ] I n mos t case s i t i s expecte d tha t manufacturer s woul d simpl yplac e th e integrate d refueling/evaporativ e caniste r wher e th e presen t caniste r i s no wlocated ; in thes e case s n o ne wdesign issue s reall yexist . d . Summary I n summary , curren t fue l an d evaporativ e emissio n system s mus t mee t th e same FMVS S 30 1 requirement s an d muc ho f th e experienc e gaine d i n designing an d building curren t system s ca n b e directl yextrapolate d t o implementing an onboar d system . Th e analysi s presente d abov e lead s t o th e conclusio n tha t straightforward , viabl e engineering solution s exis t t o addres s an ypotentia l safet ydesign concerns , an d tha t onboar d system s can b e incorporate d int o th e vehicle' s fuel/evaporativ e system withou t compromising fue l systemintegrit yo r reducing th e vehicle' s abilit yt o pas s FMVS S 30 1 requirements . Whil e an onboar d systemcan b e designe d t o provid e fue l syste m integrit ybot hi n FMVS S 30 1 testing an d in-use , i t i s pruden t t o conside r th e effect s o f maintenance , defects , tampering , an

d repair s o n thes e systems , an d mean s t o addres s an ypotentia l problem s whic hmayexist . Thes e issue s wil l b e addresse d next . B . Maintenance , Defects , Tampering an d Repair s Eve n i f a systemi s designe d properl yan d function s safel y unde r "normal " an

d "extreme " in-us e conditions , some questio n remain s a s t o th e potentia l effect s o f maintenance , defects , tampering an

d repair s o n onboard systemsafety . Maintenanc e i s th e prescribe d action s neede d t o kee p a systemoperating a s designed . Defect s involv e th e imprope r operatio n o f th e systemor systemcomponent s cause d b ydesign , manufacturing , o r assembl yerrors . Tamperin g involve s th e intentiona l disablemen t (partia l o r total ) o r remova l o f th e systemo r a componen t withi n th e system , an d repair s involv e restoring o r replacing th e systemo r systemcomponent s becaus e o f malfunctio n o r damage . Eac ho f thes e event s an d thei r safet yeffect s ar e discusse d below .-41

- 1 . Maintenanc e First , an onboar d systemi s expecte d t o b e essentiall y maintenanc e fre e (n o schedule d maintenance ) a s ar e curren t evaporative contro l systems . EPA' s emissio n facto r testing ha s foun d tha t non-tampere d fuel-injecte d vehicle s generall ycompl y wit hth e evaporativ e emissio n standard s withou t maintenance . Furthermore , EPA' s requirement s fo r light-dut ytruc k an d heavy-dut ygasolin e vehicl e emission s certificatio n d o no t allowevaporativ e system maintenanc e u

p t o 100,00 0 miles , an d a simila r requiremen t i s being considere d for an onboard system . Th e technolog

yuse d her e can b e use d fo r passenge r car s a s well . Thus , maintenanc e wil l no t b e necessaryfo r prope r functioning o f a

n onboard systemove r th e lif e o f a vehicle . Therefore , lac k o f prescribe d maintenanc e wil l no t lea d t o safet yproblems . 2 . Defect s Second , wit hregard t o defects , th e primarysafet yrelate d concer n deal s wit hth e possibilit ytha t defect s i n th e operatio n o f on e or mor e component s o f th e onboar d system in-us e migh t lea

d t o safet yproblem s fo r th e vehicle . Thi s include s possibl e problem s wit hcomponent s suc ha s th e liquid/vapo r separator , purg e valve , charcoa l caniste r an d rollove r valve . Sinc e onboar d systemcomponent s suc ha s th e liquid/vapo r separator , purg e valve , an d charcoa l caniste r ar e verysimila r t o thos e use d i n evaporativ e systems , on e metho d t o asses s th e potentia l safet yeffect s o f defect s i s t o revie wth e experienc e see n wit hevaporativ e systems . I n an effor t t o quantif yth e potentia l fo r defec t problem s regarding onboar d systems , thre e differen t compute r file s provide d b yNHTS Awer e reviewe d fo r evidenc e a s t o defect s pertaining t o th e evaporativ e emissio n syste m whic hcoul d impac t vehicl e safet yin-use.[26 ] Th e file s reviewe d covere d recalls , servic e bulleti n reports , an d owne r complaint s curren t a s o f November , 198 6 fo r al l thre e vehicl e classe s (passenge r car , ligh t truck , an d heavy-dut ygasoline) . Arevie wo f th e recal l file s reveale d onl y1 2 case s tha t coul d b e eve n remotel ylinke d t o th e evaporativ e emissio n systemou t o f a n estimate d 3,00 0 familie s whic hhav e bee n certifie d wit h evaporativ e emissio n systems . Servic e bulleti n report s fo r dealer s adde d a

n additiona l 2 1 case s fo r a tota l o f 3 3 possibl e problem s ou t o f ove r 3,00 0 families . Non e o f thes e wer e identifie d a s havin g cause d an accident ; th e vas t majorit ywer e mor e emissio n system performanc e than safet ydefects . Finally , a reviewo f th e owne r complaint s indicate d onl yabou t 10 0 problem s ou t o f ove r 18 0 millio n vehicle s sol d wit hevaporativ e emissio n controls . I n onl ya fewo f th e owne r complaint s di d safet yproblem s actuall yoccur , an d n o significan t damag e wa s reported . O n a percentag e basi s thes e potentia l problem s ar e verysmall .P.4 4
-42

- Two othe r valuabl e observation s can b e draw n fro ma revie w o f thes e files . Problems/complaint s hav e diminishe d wit hnewe r mode l yea r vehicle s wit hevaporativ e controls , whic h demonstrate s tha t gaining experienc e lead s t o produc t improvement . Give n th e similarit ybetwee n onboar d refueling an d evaporativ e emissio n controls , an d th e fac t tha t th e two systems wil l b e integrate d in mos t cases , muc ho f thi s experienc e wil l b e directl ytransferabl e t o onboar d system s an d thu s improve in-us e performance . Second , th e reviewo f th e owne r complaint s file s indicate d n o trend s othe r than thos e related t o improvement s i n newe r mode l yea r vehicles ; thu s n o systemati c problem s in component s or system s wer e evident . Further , i t i s importan t t o not e tha t th e verymechanism s use d t o generat e th e file s fo r thi s surveywoul d actuall yac t t o hel p eliminat e an ypotentia l in-us e safet yeffect s o f onboard system s defects . Deale r servic e bulleti n report s ar e effective i n dealing wit hproblem s raise d a t the

- dealerships , an d owne r complaint s assis t th e manufacturer s an d NHTS Ai n assessing th e nee d t o conduc t voluntaryo r mandatoryrecalls . Finally , t o plac e th e potentia l for defec t problem s from onboard system s i n context , i t shoul d b e note d tha t th e onboar d ris k i s essentiall yincrementa l t o tha t no wsee n fo r evaporativ e systems , sinc e i n mos t case s th e refueling an d evaporativ e system s woul d b e integrated . O n a n incrementa l basis , th e frequenc yo f defect s woul d likel yb e unaffected . Finally , sinc e a rollove r valv e coul d b e use d o n som e onboard systemdesign s specificall yt o enhanc e safet yan d the y ar e no t use d o n curren t vehicles , i t i s wort hdiscussing th e possibilit yo f valv e defects . First , i t shoul d b e note d tha t defect s i n thes e valve s shoul d b e rare . Manufacturin g engineering technique s permi t th e developmen t an d productio n o f highl yreliabl e valve s an d statistica l qualit ycontro l technique s ar e availabl e t o insur e tha t productio n valve s mee t design standards . I n fact , i f a rollove r valv e i s defectiv e a t th e vehicl e assembl ypoint , th e vehicl e wil l probabl yno t b e abl e t o accep t th e fue l provide d a t th e en d o f th e assembl y line , an

d repair s wil l b e neede d eve n befor e th e vehicl e leave s th e plant . Second , t o insur e in-us e protection , rollove r valve s mus t b e designe d t o fai l i n th e close d position . Thi s woul d b e considere d "safe " becaus e a close d positio n valv e failur e woul d neve r ceas e providing rollove r protectio n an d i t woul d effectivel ybloc k th e refueling ven t lin e an d mak e refueling th e vehicl e extremel ydifficult . Thi s difficult y woul d provid e incentiv e fo r th e vehicl e operato r t o identif y an d repai r th e failure . I f th e valv e faile d during operatio n o f th e vehicle , th e fue l tan k woul d ven t an

yvapor s throughth e limiting orific e or ga s cap t o preven t an ypressur e buil d up (Se e Figure s 3 an

d 4) . Also , rollove r valv e failur e migh t b e on e componen t o f a n onboard syste

mwhic hcoul d b e incorporate d int o onboard vehicl e diagnostic s an d thu s allo wth e operato r notic e o f th e problem whe n i t occur s an d provid e an opportunit yP.4 5

-43

- for repai r befor e th e fue l leve l become s critical . Fai l saf e design s woul d b e effectiv e i n achieving bot hprotectio n an d repair , an

d tha t th e othe r measure s discusse d abov e woul d assis t i n eliminating o r addressing an yin-us e defects . 3 . Tampering Athird are a o f potentia l safet yproblem s involve s th e effect s o f possibl e systemtampering . Whil e severa l type s o f tampering occur wit hevaporativ e emissio n system s (se e Tabl e 1) , pas t in-us e experienc e wit hthes e system s show s tha t onl y on e type , disconnectio n and/or ' remova l o f th e charcoa l canister , migh t b e a safet yproblemfor onboar d systems . Thi s typ e o f tampering pose s a possibl e safet yhazar d becaus e during th e refueling operatio n i t woul d lea d t o a flo wo f gasolin e vapo r int o th e atmospher e a t th e poin t wher e th e missin g caniste r had bee n located . Whil e th e gasolin e vapo r mixtur e reaching th e caniste r locatio n in thi s situatio n -woul d b e wel l above th e uppe r flammabilit ylimit , i t woul d - - brie f lyb e flammabl e a s th e vapo r dissipate s an d a t th e air/vapo r transitio n zones . I f a spark or othe r ignitio n sourc e wer e present , th e mixtur e coul d briefl yburn . Whil e thi s situatio n i s likel yt o b e rare , th e possibl e safet yeffect s o f suc han occurrenc e mus t b e considere d i n th e onboard systemdesign . Ther e ar e severa l point s whic hnee d t o b e mad e relativ e t o caniste r tampering . First , thi s i s no t uniqu e t o onboar d system s - simila r potentia l problem s nowexis t wit hevaporativ e emissio n canister s bu t a safet yconcer n regarding tampering wit hevaporativ e emissio n systemcanister s ha s no t surfaced . Second , using curren t evaporativ e emissio n canister s a s an indicator , thi s situatio n i s likel yt o b e rar e fo r integrate d onboard refueling/evaporativ e canisters . A s i s show n i n Tabl e 2 , curren t averag e caniste r tampering i s onl yabou t 3 percen t o f al l vehicles , an d simila r rat e woul d b e expecte d fo r integrate d refueling/evaporativ e emission s canisters . Third , i f th e caniste r wer e locate d i n an are a whic hwoul d b e difficul t t o access , tampering coul d b e furthe r discouraged . Further , th e potentia l problemcoul d b e reduce d through prope r placemen t o f th e caniste r i n a locatio n distan t froman y ignitio n sources . Possibl e location s includ e th e rea r o f th e engin e compartmen t (a s i s don e wit hsome evaporativ e canisters ) o r i n some underbod yare a a s ha s bee n suggeste d b ysome manufacturer s fo r packaging reasons . Placing th e caniste r i n an underbod

yare a woul d als o reduc e th e potentia l fo r tamperin g b ymakin g i t les s accessibl e t o th e owne r a s mentione d above . Whil e caniste r tampering i s infrequent , an d mean s exis t t o discourag e suc haction s eve n further , goo d engineering judgmen t dictate s tha t canister s no t b e place d i n a locatio n wher e tampering coul d creat e a safet yhazard . I t i s expecte d tha t manufacturer s wil l tak e al l reasonabl e step s necessaryt o reduc e tampering , an d tha t refueling canister s woul d no t b e place d i n location s wher e thei r remova l coul d creat e a safet y risk .P.4 6 -44

- Tabl e 1 Type s o f Tampering Problem s An d Typica l Rate s o f Occurrenc e Rat e o f ProblemOccurrenc e (% ) Ga s Ca p Removed

- 1 . 2 % Caniste r Vacuu

mDisconnecte d 1. 7 Cap Remove d & Caniste r Vacuu mDisconnecte d 0. 1 Caniste r Remove d 0. 3 Non-vacuu

mCaniste r Disconnectio n 0. 2 Tota l Disablement s 3.5 %

Tampering rate s calculate d fro mth e combine d dat a fro mth e EPATampering survey s performe d ,i n 1982 , 198 3 an

d 198 4 (9,14 2 vehicles) .P.4 7 -45

- ~ - Tabl e 2 Caniste r Tampering SurveyResult s

B yYear * Passenge r Ca r an

d Ligh t Truck* * Yea r I Tampere d 197 8 3 197 9 2 198 0 No Repor t 198 1 2 198 2 2 198 3 5 198 4 3 198 5 4 

### Av g

* * Moto r Vehicl e Tampering Survey- 1985 , U S EPA , OAR , OMS , FOSD , Novembe r 1986 . Sinc e HDGV s di d no t requir e evaporativ e control s unti l 1985 , surve ydat a i s currentl yno t availabl e fo r thes e vehicles .P.4 8
-46

- 4 . Repair s Finally , repair s o f onboard system s mayhav e some safet y implications . Sinc e a n onboard systemi s essentiall y maintenanc e free , an ydamag e t o th e system(beside s tha t fro m defect s o r tampering ) woul d in mos t case s resul t fro ma vehicl e accident . A

n acciden t whic hdamage s th e vehicle' s fue l system woul d b e relativel ysever e an d requir e critica l vehicl e repairs . Suc hvehicl e repairs , i n general , woul d demand a professiona l certifie d mechani c i n a license d facility . Thes e mechanic s shoul d b e properl ytraine d an d hav e acces s t o curren t shop manual s t o repai r an d packag e th e fue l systeman d onboar d component s correctl yt o ensur e effectiv e an d saf e performance . The yals o shoul d b e awar e o f an ypotentia l safet yhazard s o f imprope r installatio n or omissio n o f onboard system components . Furthermore , thes e mechanic s woul d normall yhav e no economi c incentive for improperl yrepairing a n onboar d systemo r omitting som e component s sinc e th e facilit ywoul d b e compensate d fo r al l o f th e part s an d time spen t repairing th e vehicle . I n an yrepair s o f th e fue l systemwit han onboar d contro l system , ther e i s onl yon e critica l are a wit hrespec t t o safety . Thi s critica l are a i s th e connecting lin e betwee n th e top o f th e fue l tank an d th e rollove r valv e a t th e to p o f th e fillpipe . An imprope r installatio n or connectio n i n thi s are a coul d resul t wit hfue l leakag e i n th e even t o f a vehicl e rollover . Thi s connection , however , i s no t uniqu e t o fue l tank s wit honboar d systems . I t i s verysimila r t o th e externa l vapo r ven t lin e tha t appear s o n man yo f today' s vehicles , an d thu s incrementall yth e situatio n mayb e n o differen t tha n o n today' s vehicles . Thus , repair s o f onboar d system s shoul d no t creat e an

ypotentia l safet yhazard s a s compare d t o presen t da y fue l systems . 5 . Summary I n summary , componen t maintenance , defects , tampering , o r repair s shoul d no t creat e th e potentia l fo r in-us e safet y risks . An onboar d systemi s expecte d no t t o requir e an y schedule d maintenance . Thus , an ylac k o f maintenanc e b yth e vehicl e owne r shoul d no t introduc e safet yhazards . Ther e i s n o evidenc e t o indicat e tha t possibl e defect s i n othe r onboar d systemcomponent s woul d lea d t o safet yproblems . Ther e ar e ver yfewdefect s wit hpresen t evaporativ e emissio n systems , an

d sinc e i t i s likel ytha t refueling an d evaporativ e emissio n system s woul d b e integrated , th e overal l defec t rat e i s likel yt o b e no differen t tha n tha t see n i n presen t vehicles . Further , method s ar e availabl e t o assur e tha t reliabl e rollove r valve s ar e installe d i n vehicle s an d t o insur e rollove r protectio n i n th e unlikel yeven t o f a valv e failure .-47

- Whil e caniste r tampering effect s mus t b e considered , i t shoul d b e note d tha t i t presentl yi s uncommon , an d thi s lo

w rat e i s expecte d t o continu e fo r onboar d systems . Also , tampering coul d actuall ydecreas e throughjudiciou s caniste r placemen t o n th e vehicle . Nevertheless , pruden t desig n practice s dictat e tha t manufacturer s no t plac e canister s i n a location wher e tampering coul d lea d t o a safet yproblem , an d i t i s expecte d tha t thi s approac hwoul d b e followed . An yrepair s o f an onboard system , beside s thos e resulting fro mdefect s or tampering , wil l probabl yoccur a s a consequenc e o f acciden t damag e t o th e vehicle . Sinc e th e damag e wil l mos t likel yb e severe , i t wil l requir e th e us e o f a certifie d mechani c wh o i s properl ytraine d fo r suc hrepairs . Further , th e onl ycritica l are a o f th e onboar d systemwhic hcoul d impos e an ysafet yhazar d i f improperl yrepaire d ar e th e component s an d connection s betwee n th e fue l tan k an d fillpip e top . Repair s ar e als o critica l i n thi s are a fo r curren t vehicle s usin g externa l vapo r ven t lines , s o ther e mayb e n o chang e i n ris k ove r presen t vehicles . Repair s t o an onboar d systemshoul d no t inherentl yincreas e th e potentia l fo r in-us e safet yrisks . An onboar d systemdesign mus t als o includ e consideratio n o f potentia l effect s o n th e safet yo f refueling operations . Thi s i s discusse d i n th e nex t section . C . Refueling Operatio n Safet y 1 . Fue l Tank Overpressur e During Refuelin g Th e firs t potentia l safet yissu e involve s th e possibilit y o f pressur e build-u p i n th e fue l tank during th e refueling o f a vehicl e equippe d wit han onboar d system . Wheneve r a systemi s designe d t o b e "sealed " fro m it s environment , some forethough t mus t b e exercise d t o evaluat e th e possibilit yan d consequence s o f an overpressur e withi n th e system . Althougha

n onboar d systemdoe s no t completel ysea l of f a vehicle' s fue l tank , i t i s designe d t o allo wfo r onl yon e opening , th e refueling vapo r ven t line . I f fo r some unusua l reason , th e ven t lin e wer e t o become full yo r partiall yblocke d o r th e nozzl e automati c shut-of f mechanis m faile d durin g a ful l refill , exces s pressur e coul d buil d i n th e fue l tank . Thi s concer n i s onl yassociate d wit han onboar d system utilizing a mechanica l sea l a s illustrate d i n Figur e 3 . Wit ha liqui d sea l system(se e Figur e 4) , exces s pressur e canno t buil d up i n th e tank during refueling becaus e fue l woul d simpl yflo wou t th e fillnec k opening (the same wayi t currentl ydoes ) an d th e nozzl e operato r coul d the n stop th e fue l flow . Liqui d sea l system s woul d functio n i n th e same manne r a s curren t fue l systems . Fromth e nozzl e operator' s viewpoint , th e refueling operatio n remain s th e same .P.5 0 -48

- I f a manufacture r elect s th e mechanica l sea l design , h e mus t incorporat e a simpl e pressur e relie f devic e capabl e o f relievin

g fue l tan

k pressure. . I n th e even t o f a nozzl e failur e or ven t line blockage , thi s devic e woul d eliminat e potentia l tan k overpressurizatio n b yopening an "emergency " passag e t o th e atmospher e throughwhic hpressurize d vapo r an d an ygasolin e woul d spil l ont o th e pavemen t or some othe r locatio n noticeabl e t o the nozzl e operator . Thi s spillag e woul d mak e th e fue l pum p operato r awar e o f the probleman d fue l flowcoul d b e stoppe d withou t causing damag e t o th e fue l systemo r causing fue l t o spitbac k o n t o th e operator . Ther e hav e bee n severa l differen t design s suggeste d fo r suchpressur e relie f devices . Asampl e desig n i s show n i n Figur e 1 7 whic hwoul d b e incorporate d directl yint o th e design o f the fillpip e s o tha t th e conditio n woul d b e noticeabl e b y th e operator.[18 ] Th e operato r woul d the n b e prompte d t o repai r an

yproblem s i n orde r t o resume norma l refueling actions . (The nee d for promp t repai r woul d hav e positiv e safetyan

d ai r qualit yimplications. ) A s wa s show n i n Figur e 9 , i t migh t als o b e possibl e t o incorporat e th e pressur e relie f functio n int o some othe r componen t o f th e systemsuc ha s th e rollove r valve . An yoverpressur e concern s can b e eliminate d througha simpl e pressur e relie f devic e suc ha s these . 2 . Pre-RefuelinqOverpressur e Effect s Anothe r potentia l safet yissu e raise d relating t o refueling operation s ha s t o d o wit hth e "U " bend i n th e "J-tube " fillnec k seal . I f th e tan k ven t becam e blocked , an d pressur e buil t u

p substantiall yi n th e tank , upo n remova l o f th e fue l cap , th e liqui d gasolin e whic hwa s lef t standing i n th e "U " ben

d coul d b e spi t bac k ou t th e fillpipe . Thi s concer n can b e easil yaddresse d b ydrillin g a smal l hol e i n th e bottom o f th e "U " ben

d (se e Figur e 4 an d 5) , whic h woul d allowan

yfue l lef t standing i n th e fillpip e subsequen t t o a refueling even t t o drai n ou t int o th e fue l tank . Give n th e rang e o f fue l dispensing rate s see n in-use , thi s hol e ca n b e size d t o quickl yprovid e drai n capacit yan d stil l provid e th e sea l neede d during refueling . Furthermore , th e hol e siz e can b e size d s o tha t n o foreign objec t wil l bloc k i t durin g a refueling event . B yevacuating th e colum n o f fue l lef t standing i n th e fillpipe , th e potentia l for spitbac k t o occu r upo n remova l o f th e fue l tan k cap woul d b e eliminated . Fillpipe s wit ha "J-tube " sea l employing a drai n hol e hav e bee n tested . Thes e test s showtha t thes e seal s provid e refueling emissio n contro l efficiencie s comparabl e t o thos e o f mechanica l seals.[16 ]P.5 1

OJ u -3P.5 2 -50

- 3 . Summary Th e analysi s presente d above demonstrate s tha t simple , straightforward engineering solution s exis t fo r th e specifi c concern s raise d b

ythe commenters . I n al l cases , manufacturer s have a numbe r o f design option s availabl e t o addres s thes e concerns . V . In-Us e Fue l SystemSafet y 1 . Summaryo f Concern s Some concern ha s bee n expresse d tha t an ytime a system increase s i n siz e or complexity , th e potentia l fo r a failur e withi n th e systemals o increases . Applying thi s lin e o f thinking t o vehicl e emissio n contro l systems , i t ha s bee n suggeste d tha t onboard system s woul d inherentl ydecreas e overal l fue l system safet ybecaus e severa l component s ar e large r an

d a fewmor e component s ar e neede d than.-for curren t evaporative emissio n systems . In-us e vehicle s ar e subjec t t o innumerabl e acciden t situations , an d some concer n exist s a s t o whethe r o r no t a

n increas e i n componen t size/numbe r coul d lead t o safet yproblems . Further , i t ha s bee n state d tha t eve n i f a vehicl e fue l syste mi s saf e enought o pas s FMVS S 301 , i t doe s no t insur e tha t i t i s fre e o f al l safet yrisk s in-us e a s evidence d b yth e numbe r o f vehicl e cras hfire s tha t occu r eac hyear . I t ha s bee n argue d tha t vehicle s equippe d wit han onboar d systemcoul d pas s al l FMVS S 30 1 test s an d ye t directionall yincreas e ris k in-us e b

ysome unquantifiabl e (presumabl ysmall ) amount . Thus , i t follow s tha t becaus e some in-us e situation s diffe r from FMVS S 30 1 tests , onboard system s mus t no t onl yb e designe d t o b e capabl e o f passing Federa l safet ystandards , bu t thes e system s mus t als o b e designe d s o a s no t t o increas e in-us e ris k fo r fue l systemrelate d hazards . 2 . Analysi s o f Issue s Fundamentally , EPAbelieve s tha t overal l ris k in-us e shoul d no t increase . And , whil e i t i s tru e tha t FMVS S 30 1 canno t protec t agains t everyconceivabl e in-us e situation , manufacturer s ar e motivate d t o conside r fue l systemsafet y implication s fo r reason s othe r than insuring tha t thei r vehicle s pas s Federa l safet ystandards . Manufacturer s mus t determin e wha t theyconside r t o b e an appropriat e leve l o f safet yan

d in-us e risk , an

d the n design thei r vehicle s t o mee t thi s level . Ofte n thi s lead s t o differen t overal l level s o f safet yi n differen t vehicl e models . Befor e discussing ho wt o addres s thi s issue , i t i s valuabl e t o discus s ho wsafet y concern s ar e integrate d int o th e overal l vehicl e desig n an d developmen t process .P.5 3 -51

- First , safet yi s an integra l par t o f th e desig n proces s an d i s normall yno t considere d incrementally . However , managing ris k involve s a serie s o f trade-offs , balances , an d compromise s wit hothe r keydesign criteria . Manufacturer s choos e no t t o mak e thei r vehicle s fre e o f al l ris k becaus e o f othe r vali d design consideration s suc ha s performance , styling , weight , cost , an

d othe r factors . I t i s generall yaccepte d tha t no technologica l constraint s exis t whic hwoul d preven t th e productio n o f a nearl y"fire-proof " vehicle , an d certainl y vehicle s coul d b e mad e safe r than theycurrentl yar e a s evidence d b

ynumerou s "safet ycar " designs.[27 ] However , cos t an d othe r consideration s ar e vali d an d theypreven t "zero " ris k (or a perfectl ysaf e vehicle ) fro mbein g considere d appropriate . On e analys t ha s stated , "I t i s definitel yno t reasonabl e t o expec t manufacturer s t o produc e 'Sherman Tanks '

.. . a s suc hvehicle s woul d neithe r serv e th e need s o f societa l safety , mobility , or economy."[28 ] Thi s same logi c an d ris k managemen t process - applie s t o fue l system

safety . Factoring safet yint o fue l system desig n i s a complicate d proces s tha t involve s numerou s tradeoff s an d compromise s a s above . Fue l systemdesign s ar e no t al l alike , an d fue l systemsafet yconsideration s varyfro mon e desig n t o another . Fo r example , fue l tan k siz e an

d locatio n o n th e vehicl e hav e a substantia l impac t o n a vehicle' s safet ydurin g a collision . Rea r fil l tank s ar e i n a mor e acciden t pron e locatio n tha n sid e fil l tanks , an d ar e usuall ylocate d close r t o th e exterio r shel l o f vehicle . Sid e fil l tank s ar e generall yconsidere d safe r than rea r fil l tanks , an d consequently , rea r fil l fue l tank s ar e graduall ybeing phase d ou t o f vehicl e designs . However , i t shoul d b e note d tha t thi s chang e ove r ha s no t occurre d immediatel ydu e t o othe r desig n consideration s suc ha s cos t an d conflicting interactio n wit h othe r aspect s o f th e tota l vehicl e design . Asimila r se t o f argument s ca n b e mad e wit hplasti c versu s meta l fue l tanks . Thes e simpl e example s demonstrat e ho wrisk s ar e manage d relativ e t o othe r considerations . Eve n curren t fue l system s coul d b e safe r bu t some ris k i s accepted . Anothe r interesting exampl e lie s i n th e are a o f fue l systemexterna l plumbin g suc ha s emissio n contro l vapo r line s o r externa l ven t line s along th e fillpipe . A t on e time adde d piping connection s simila r t o th e externa l vapo r ven t line s tha t appea r o n some o f today' s vehicle s wer e characterize d a s an unacceptabl e adde d safet yris k b yGenera l Motors.[29 ] Afte r furthe r testing an

d design , tha t same manufacture r incorporate s an externa l vapo r ven t lin e int o man yo f it s curren t vehicle' s fue l systems . wit hsafet yengineering an d fiel d testing an y potentia l safet yrisk s associate d wit hthes e externa l ven t line s ha s bee n managed .P.5 4 -52

- Thi s particula r design chang e illustrate s a very significan t aspec t o f fue l systemsafety . Eve n thoughconcer n existed ove r th e potentia l safet yaspect s o f additiona l fue l syste mplumbing , th e mer e fac t tha t thes e additiona l line s appear o n today' s vehicle s confirm s tha t safet yconcern s ca n b e technicall yaddresse d i f desired . An yperceive d in-us e ris k can b e managed . Safet ydoe s no t hav e t o b e an obstacl e t o fue l syste m improvement s or modifications . Th e technolog yt o reduc e safetyrisk s i s currentl yavailable , an d th e degre e t o whic hi t i s utilize d depend s o n howmuc hris k a manufacture r i s willin g t o accept . A s illustrate d in th e discussion s above , manufacturer s accep t or manag e varying amount s o f ris k i n orde r t o strik e a balanc e o r compromis e wit hal l o f th e importan t desig n criteria . Clearl ysafe r vehicle s coul d b e made , an d th e amoun t o f in-us e ris k reduced . A s consideration s change , th e amoun t o f ris k accepte d mayals o change . Ofte n th e leve l o f acceptabl e ris k mayb e mor e constraine d b yin-us e liabilit y concern s than governmen t safet ytests . Fo r example , cras h testing result s fro mNHTSA' s ne wcar assessmen t progra msho w tha t th e vehicles ' abilit yt o protec t it s occupant s fro minjury varyb yvehicl e model.[30 ] Differen t vehicl e model s provid e differen t level s o f protectio n fo r th e head , chest , an d femur during barrie r cras htesting a t 3 5 mph . Some manufacturer s chos e t o incorporat e safe r design s o n some model s fo r liabilit y an d perhap s marketabilit yreasons . Similarly , th e safet yo f an onboar d systemo n in-us e vehicle s wil l depen d o n th e desig n decision s mad e b yth e manufacturers . Onboar d system s woul d increas e th e siz e an d numbe r o f fue l systememissio n contro l components , an d some concern ha s bee n expresse d tha t th e safet yo f thes e component s i n FMVS S 30 1 testing mayno t necessaril yb e indicativ e o f in-us e performance . However , adding thes e system s doe s no t nee d t o affec t th e leve l o f ris k a manufacture r i s willin g t o o r can afford t o accept . A s wit han yothe r systemchange , manufacturer s woul d integrat e onboar d system s int o thei r vehicles ' fue l system s withou t increasing overal l systemrisk , an d clearly , ther e ar e n o inheren t technica l constraint s prohibiting themfro mdoing so . Further , ther e i s littl e meri t t o th e assertio n tha t an onboard system

mus t b e inherentl yles s saf e tha n an evaporativ e emissio n systembecaus e i t i s mor e "complicated" . Addin g a few component s an

d enlarging a coupl e o f other s present s n o ris k whic hcanno t b e manage d t o level s no wdeeme d acceptable . A s a matte r o f fact , man yo f th e improvement s recentl yimplemente d o n passenge r car s an d light truck s hav e resulte d i n vehicles/system s whic har e increase d i n bot hsafet yan d complexity . Conside r fo r exampl e advance s mad e i n vehicle/engin e contro l systems . Electroni c engin e control s hav e increase d vehicl e engin e complexit ytremendousl yove rP.5 5 -53

- previou s systems , ye t ther e i s n o evidenc e tha t thes e system "complications " hav e jeopardize d safety . I n fact , manufacturer s ar e no wconsidering compute r control s fo r othe r vehicl e system s suc ha s th e suspensio n an d handling , wit hth e direc t purpos e o f improving vehicl e safety.[31 ] Amor e complicate d system doe s no t impl ya les s saf e on e i f give n prope r consideratio n during design . A s discusse d in detai l earlier , manufacturer s hav e man y option s availabl e i n th e design o f a n onboar d systemwhic hca n manag e o r eliminat e an yperceive d increas e i n in-us e risk . However , fo r manufacturer s wit hspecia l concern s regarding in-us e safet yther e ar e eve n mor e design option s available . Fai l safe , redundant , o r breakawayrollove r valve s coul d b e used . Th e integrit yo f th e critica l portio n o f vapo r lin e betwee n th e fue l tan k an d rollove r valv e coul d b e assure d throughth e us e o f stee l brai d covere d rubbe r hos e i n keyarea s o r stee l tubing.[32 ] Bot hrubbe r an d stee l vapo r line hav e bee n use d o n pas t vehicl e models . I f chafing o f thi s critica l portio n o f vapo r lin e i s a concern , th e affecte d area s coul d b e wrappe d i n a spira l spring for protection . Also , slac k coul d b e provide d i n thi s critica l portio n o f vapo r lin e t o minimiz e th e possibilit yo f separatio n o r ruptur e i n an accident . Improve d o r additiona l fittings , adhesives , o r clamp s coul d b e use d t o increas e th e strengt ho f keyvapo r lin e connection s betwee n th e fue l tank an d th e rollove r valve . Concern s relate d t o th e charcoa l caniste r can b e addresse d b yusin g a reinforce d caniste r shel l o r a protectiv e barrier . Whil e thes e mayb e somewha t extraordinary , thi s brie f listing demonstrate s tha t furthe r desig n option s ar e availabl e whic hi f use d coul d improve safet yove r curren t vehicles . I n summary , manufacturer s can manag e thei r in-us e ris k an d can choos e t o mak e an onboar d system a s saf e a s the ydeem appropriate . Onboar d system s presen t n o safet yconcern s whic h canno t b e eliminate d throughprope r design , an d eac h manufacture r wil l develo p th e fue l systemdesig n whic h represent s th e bes t balanc e fo r eac hparticula r vehicl e model , wit hful l consideratio n o f th e safet yrisk s an d al l othe r ke y factors . 3 . Opportunitie s fo r Improvemen t Implementing onboar d control s coul d actuall yresul t i n a ne t improvemen t i n overal l fue l systemsafety . Sinc e manufacturer s woul d nee d t o redesign some aspect s o f thei r vehicles ' fue l system s t o incorporat e onboar d systems , th e opportunit ywoul d b e provide d t o reexamin e othe r aspect s o f fue l systemsafet ya s well . Some o f th e potentia l fue l system improvement s tha t coul d resul t fro mthi s reexaminatio n includ e an acceleratio n o f th e transitio n fro m rea r fil l t o sid e fill , integratio n o f th e curren t externa l vapo r ven t lin e insid e th e fillpipe , bette r placemen t o f th e fue l tank , o r eve nP.5 6 -54

- improvemen t i n th e fue l tan k integrit yitself . Also , an ynumbe r o f othe r mino r modification s o r improvement s i n th e fue l o r emission contro l system s coul d b e mad e whic hcoul d enhanc e safetyan

d performanc e an

d perhap s reduc e cost . Thes e includ e area s sucha s tan k venting , purg e valv e operation , an d eliminating man

yproblem s identifie d throughowne r complaint s an d othe r simila r surveymeasures . Also , i t i s likel ytha t a n onboard refueling contro l requiremen t woul d lea d t o a decreas e i n th e amoun t o f fue l spilled in-us e an

d thu s improve th e overal l safet yo f refueling events . I n the certificatio n refueling test , vehicle s woul d hav e t o b e designe d t o accommodat e a refueling dispensing rat e nea r th e highen

d o f the presen t rang e o f in-us e value s (8-1. 0 gallon s pe r minute ) withou t an yspillag e or spitbacks . Thi s i s becaus e an

yfue l spille d during th e tes t i s considere d a s par t o f th e tes t results . Sinc e on e tablespoo n o f gasolin e evaporate s t o a substantia l amoun t o f vapo r (abou t 1 0 grams) , almos t an

yspillag e tha t occurre d during th e certificatio n tes t woul d resul t i n a failure . Thus , th e tes t procedur e requirement s wil l insur e tha t manufacturers ' fue l system fillpip e design s ar e capabl e o f handling dispense d fue l a t flo w rate s u p t o 1 0 gallons/minut e withou t allowing an yspitback . Th e us e o f thes e fillpip e design s ar e predicte d t o lea d t o a reductio n i n th e amoun t o f fue l spille d in-use . Thi s i s compare d t o some curren t vehicl e fillpip e design s whic hhav e difficult yaccepting fue l a t th e lowe r en d o f th e in-us e rang e (8-1 0 gpm ) withou t spitback . T o assur e thi s benefi t accrue s i n the lon

g term , EPAi s considering a n in-us e dispensing rat e limi t o f 1 0 gallon s pe r minut e along wit han yonboar d requirement . Also , fro

mth e analysi s presente d above , i t i s eviden t tha t implementing onboar d control s woul d provid e a t leas t thre e othe r direc t safet ybenefit s ove r presen t systems . First , depending o n th e design used , adding a rollove r protectio n devic e mayimprove th e safet yo f presen t fue l tank system s whic hus e a 1/2 " externa l ven t line withou t rollove r protection . Second , adding a rollove r valv e ma yenhanc e th e safet yfo r thos e vehicle s whic hno wus e a limiting orific e fo r rollove r protection , sinc e a rollove r valv e wil l provid e a positiv e sea l i n lie u o f th e "controlle d leak " approac h provide d b

yth e limiting orifice . Las t o f all , i t shoul d b e note d tha t refueling vapor s ar e currentl yvente d t o an are a whic hpose s somewha t o f a safet yhazard . Thi s i s becaus e th e potentia l exist s fo r refueling vapor s t o ignit e inadvertentl y a s theyescap e fro m th e fillnec k opening . However , a s onboar d control s ar e phase d in , an d mor e an

d mor e vehicle s rout e refueling vapor s awa yfro mth e fue l pum

p operato r t o a safe r poin t (the charcoa l canister ) th e overal l ris k involve d i n refueling a vehicl e wil l b e reduced .P.5 7
-55

- Finally , t o addres s an yspecia l concern s regarding onboar d syste mcrashworthines s an d t o perhap s improve crashworthines s ove r curren t vehicles , ther e i s a n alternativ e onboar d system design availabl e whic hmanufacturer s mayelect . A s i s show n i n Figur e 18 , thi s systemi s simila r t o Figur e 4 , excep t al l th e neede d valve s (rollover , vent , liquid/vapo r separator ) ar e buil t int o th e top o f th e fue l tank , instead o f externally . Asolenoi d activate d rollove r valv e coul d b e use d (Figur e 19 ) whic hi s located o n to p o f o r insid e th e fue l tank . [33 ] Thi s valv e woul d normall yb e close d excep t durin g refueling whe n i t woul d b e electronicall yopene d b ya switc hlocate d nea r th e opening o f th e fillpipe . Th e switc hcoul d b e activate d eithe r b

yth e opening o f th e doo r ove r th e fue l cap o r remova l o f th e fue l ca

p itsel f (se e Figur e 20) . Ye t anothe r approac hi s a mechanica l bal l valve . Thi s devic e woul d normall yremai n ope n t o provid e a- clea r vapo r passage . However , in th e even t o f a rollove r acciden t gravit y cause s a meta l bal l t o rol l int o a fitte d sea t an d sea l of f th e ven t line . On e variatio n o n thi s design (se e Figur e 21 ) woul d b e simpl e mechanica l bal l valv e buil t i n combinatio n wit hothe r neede d valves.[15 ] A s i s show

n i n Figur e 18 , thi s onboar d systemdesig n ma y nee d a fil l limite r t o allowfo r norma l refueling operation s (i.e. , automati c shut-off ) an d t o preven t overfillin g th e tank during ful l refills . Asampl e desig n i s show n i n Figur e 22.[33 ] Th e operatio n o f th e fil l limite r i s quit e simple . Whe n th e tan

k i s ful l th e floa t rise s i n th e fil l limite r an d close s of f th e refueling ven t line . Thi s cause s pressur e t o ris e i n th e tank , subsequentl yfue l run s u p th e fillpip e an d activate s th e nozzl e automati c shu t of f mechanism . Whil e incorporatio n o f a fil l limite r i s quit e simpl e froman engineering perspective , th e design woul d hav e t o incorporat e a "sof t close " t o avoi d bac k pressur e "spikes " an d possibl e spill s a t th e en

d o f a ful l refill . Froma safet yperspectiv e thi s alternativ e i s attractiv e becaus e al l th e externa l component s ar e eithe r remove d o r mounte d i n a mor e protecte d location . Th e externa l ven t lin e (Figur e 1 ) ca n b e eliminate d an d th e othe r systemvalve s an d vapo r line s ar e move d awa yfro mth e vehicl e shel l t o a mor e protecte d are a withi n th e vehicl e body . Also , n o vapo r lin e exist s betwee n th e fue l tan k an d th e rollove r valve , s o vapo r lin e integrit yan

d connection s ar e les s critical . Finally , depending o n ho whigha priorit ya manufacture r assign s t o safet yo r i f significan t in-us e ris k i s perceived , a collapsibl e bladde r tank desig n coul d b e use d t o mee t th e onboar d requirement . Bladde r tank s coul d lea d t o a substantia l improvemen t i n fue l systemsafet yb yproviding an additiona l shel l o f protectio n t o hel p reduc e fue l spillag e i n cas e o f an. PRESSURE/VACUU M RELIE F CAP Figur e 1 8 ALTERNATIV E INTEGRATE D EVAPORATIVE/REFUELINGSYSTE M

TANK MOUNTE D VALVE S REA R MOUNTE D CANISTE R J-TUB E SliA

L

»., .

MJJCI1ANICA

LO RSOI.ENOI D ACTUATE

D VENT/ROUDVE R VALVE , LIMITIN GORIFIC E & LIQUID/VAPO RSEPARATOR I c n as I PURG E VALV E 5/0 " DIA

. 3 ' LON G

J *- J-TUB ESEAT , ^CONTROLLE D LEAK 3/8 " DIA
. 5 ' LON G 

# i}—t«H- T O PURGE INDUCTIO N POIN T

• 3 LITE R CANISTE R

1 4 GALLO NFUE L TAN K

U l o oFigur e1 9



### £A P 7 

### ACT^ATOK SOLENOI D \/ALV £ 

### 05O " aY^AS S

BAUU-IKJ-cCAc^ e I u n

- J I



### M O 5CAL g

SCHEMATI C O FPOTENTIA L ONBOAU D VAPO RBECOVEH Y SYSTE M S C 

# L^fi | A MUELLE R ASSOCIATES . INC . |£2(f40 l • - IOOIWOO O •THCC f •ALVIMOIIC . MAMVLAM O 3 1 3 2 ? MNUAI Vat . ••• •Figur e2 0

»* . p 6jA S CA P



# 1 ^j "

LKOKieKilA^. ^

SWIf^ H LSJA S CA P POOR



### C\AS CAP

T O ALLO W 

## K^H^ )V/A L

## ^ f CAp 

## ) i 0 0 I

POTENTIA L MOMENTAK Y SWITC H LOCATION S 

### tJOjSCAUL 

# K B MUELLE R ASSOCIATES . INC . 140 1 • . COOCWOO O ITHfl T •ALTIMOIIC . MANTLAN O 2122 ? JANUAR YJI . !•• •P.6 1 -59 -
Figur e2 1 

### COMBINATIO N VALV E

^0.0. * .* • 1.0 .

WLLOVC TSHUTOF F
1/2 - Ol AS S BAL L ?/• ' 1.0 . •SCREE N

I l/ f .OVERFIL L SHUTOF F

.TA*A»A*A'»'A7A»A*A'rA'»A*A»A^A»AVA*ATA*ATA T

A*A*A*ATA*A*ATA»A*A*A*A'A*ATA*A*A*A^A* A ATATAVATA , »AVAViTATATAVAVAT»TA»A , 'A»A'r » •» ' s. s MCS H

ViWiWAWiWiWAV I 

### s - VAPOR LIQUt O SEPARATO R-60 - P.6 2

C d > J < > < sfl

C U < 

### u i 

### z I J <



# I

- A 

### 3-61

-

accident . Also , a bladde r tan k coul d eliminat e essentiall yal l o f the safet yconcern s raise d regarding contro l o f refueling emissions . Thi s i s becaus e a vapo r spac e woul d no t b e presen t i n a bladde r tank , an d withou t a vapo r space , refueling emission s woul d no t occur . Thu s neithe r a refueling emission s canister , externa l plumbing , or a rollove r valv e woul d b e needed . I t migh t eve n b e possibl e t o eliminat e th e presen t evaporative systeman d enhanc e safet yeve n more . Also , bladder s shoul d b e an attractiv e optio n fo r thos e wh o clai m hig hcost s or packaging problem s wit hcanister-base d onboar d systems . EPAi s quit e intereste d i n collapsibl e bladde r tank s a s a n optio n t o canister-base d onboar d systems . Thi s analysi s o f design an

d i n us e safet yissue s an d th e associate d cost s an d leadtim e i s no t directl yapplicabl e t o collapsibl e bladde r tanks . However , EPAplan s t o furthe r explor e th e cos t an d technologica l feasibilit yo f bladder s a s wel l a s thei r safet y an d emissio n benefits . I n conclusion , th e informatio n an d rational e presente d above refut e th e assertio n tha t adding an onboar d systemwoul d directionall yincreas e in-us e risk , eve n i f onl ybysome unquantifiabl e (presumabl ysmall ) amount . An yperceive d ris k i s manageable , an

d furthermore , i t appear s tha t th e ne t effec t o f an onboar d refueling contro l requiremen t coul d b e a potentia l increas e i n fue l systemsafety . A s discusse d above , an d i n Sectio n I

V ther e ar e numerou s desig n alternative s t o addres s th e safet yconcern s raised . T o varyin g degree s al l option s hav e th e potentia l t o improv e th e safet yo f fue l system s in-use . VI . Cos t an

d Leadtime Consideration s Th e comment s receive d regarding onboar d vapo r recovery system s als o addresse d th e cos t an d leadtime implication s o f implementing suc hcontrols . Mor e specifically , severa l o f th e comment s addresse d onboar d safet ycost s i n some for m(usuall y addressing hardwar e costs) , an d severa l commenter s expresse d som e concer n ove r EPA' s leadtime estimate . An analysi s o f th e cost s an

d leadtime necessaryt o implemen t onboar d control s safel yi s an integra l par t o f th e overal l evaluatio n o f th e feasibilit yo f thi s contro l approach . A s wa s mentione d above , cos t i s on e o f th e othe r keyconsideration s whic hi s ofte n balance d carefull yagains t safet yconcerns , an d th e cost s neede d t o implemen t onboar d system s safel ymus t b e reasonabl e relative t o othe r safet ycost s an d th e overal l cost s o f onboar d systems . Further , th e analysi s mus t carefull yconside r th e manufacture r leadtime neede d t o implemen t onboar d control s o n thei r productio n vehicles . Thi s include s th e tim e neede d t o identify , evaluate , an d addres s al l safet yconcern s an d t o compl ywit hth e tes t requirement s prescribe d i n FMVS S 301 .P.6 4 -62

- Th e firs t portio n o f thi s sectio n addresse s onboard safety costs ; th e secon

d discusse s leadtime an d describe s th e basi s fo r EPA' s leadtime estimate . Some o f th e cos t figure s cite d in th e safet ycos t analysi s ar e draw n fro ma broade r EPAanalysi s whic hdevelop s tota l onboar d syste mcost s i n 198 4 dollars.[17 ] A . Safet yCost s A s i s eviden t fro

mth e discussio n presente d in Sectio n IV , th e cost s neede d t o implemen t onboard control s safel yfal l in severa l areas . R& D typ e cost s wil l b e incurred , some ne wor modifie d component s wil l b e neede d whic hmayslightl yaffec t vehicl e operating costs , an d safet ycertificatio n testing wil l b e necessary . Howeve r befor e beginning a discussio n o f thes e costs , i t i s valuabl e t o discus s ho wth e FMVS S 30 1 standard s an d EPA' s evaporativ e emissio n contro l requirement s impac t onboard safet ycosts . Th e contro l o f refueling emission s through , a n onboar d systemwoul d no t b e th e firs t Federa l regulatio n t o requir e an investmen t t o improv e fue l syste msafety . Th e firs t fue l systemintegrit ystandard s (FMVS S 301 ) wer e implemente d b y NHTS Afo r 196 8 vehicles , an d sinc e the n ther e hav e bee n 2 majo r addition s t o thes e requirements . Eac ho f thes e ne w requirement s ha s cause d a smal l cos t increase , bu t eac hha s als o led t o an improvemen t in fue l systemsafet yo n in-us e vehicles . I n th e mi d 1970's , FMVS S 30 1 wa s substantiall y upgrade d t o extend th e coverag e o f impac t type s t o includ e rollove r event s and , rea r en d an d sid e collisions . A198 3 NHTS ATechnica l Repor t describe s th e natur e o f th e modification s mad e i n respons e t o th e upgrading o f th e standar d an d estimate s th e cost s incurre d b yvehicl e manufacturer s i n orde r t o mee t th e revise d standard an d provid e a highe r leve l o f in-us e assurance.[21 ] Tabl e 3 describe s modification s tha t wer e mad e t o 197 7 mode l yea r vehicl e fue l system s in respons e t o th e increase d requirement s o f FMVS S 301 . Thes e modification s range d fro m mino r change s suc ha s th e sligh t revisio n o f mountin g bolt s o r clip s t o mor e majo r one s suc ha s recontouring th e fue l tank . Base d o n informatio n submitte d t o NHTS Ab yvehicl e manufacturers , th e averag e (sales-weighted ) cos t increas e require d t o mak e thes e modification s wa s $4.6 0 pe r vehicle. * Thes e modification s wer e als o estimate d t o increas e vehicl e weigh t slightl y(a n averag e o f thre e pound s pe r vehicle) , whic h woul d ten

d t o marginall yincreas e th e amoun t o f fue l consume d ove r th e lif e o f th e vehicl e (abou t 3 gallon s o f fuel) . Whe n thes e two cost s ar e added , NHTS Aestimate d th e tota l safet y cos t resulting fro mth e 197 7 revision s t o FMVS S 30 1 average d abou t $8.5 0 pe r vehicl e (198 2 dollars) . ABurea u o f Labo r Statistic s analysi s estimate d tha t vehicl e cost s incurre d t o mee t th e 197 7 revisio n t o FMVS S 30 1 wer e $4.7 0 an

d cost s t o mee t th e 197 6 revisio n t o th e standar d (added rollove r test ) cos t $2.10.[34,35 ]P.6 5 

### -63

- Tabl e3 Summar y o f Vehicl e Modification s i nRespons et o 301-7 7 Vehicl eComponent s Fue lSyste m Component s Fue lTan k

Fue l Gaug e Senso r Fue l Line s Fue l Vapo r Line s Fue l Pum

p Modification(s ) t o Improve Crashworthines s

- Increas e gauge , o f tan k materia l

- Add protectiv e shiel d

- Recontou r t o minimiz e contact/punctur e b

yothe r adjacen t vehicl e components .

- Strengthen/shiel d fille r nec k

- Increas e strengt ho f solder/wel d seams

- Strengthe n mounting b yadding brackets , revising mounting bolts , increasing tor.qu

e o f mountin g strap s

- Strengthe n fille r cap seal , improve impac t resistanc e

- Strengthe n mountin g

- Recontou r

- Recontour , revise , revis e clamp s

- Provid e shiel d Othe r Vehicl e Component s Change d t o Improv e Fue l SystemIntegrit y Rea r Floo r Pan/Suppor t Rails/Whee l Housing Rea r Suspensio n (Springs , Shoc k Absorbers )

Rea r Axl e Assembl y

t m Rea r Axl e Assembl y Sea t Bel t Bracket s Engin e Moun t Powe r Steering Pum

p Bracke t - Revise , ad d support s

- Chang e suppor t brackets , revis e mountin g bolts , revis e mountin g procedure , an

d shiel d

- Mino r change s i n contou r o f lines , scre wheads , mountin g clips , recontou r ven t cove r

- Revis e hing e assembl y

- Revis e anchorag e

- Sligh t revisio n

- Sligh t revisio nP.6 6
-64

- Base d o n an evaluatio n o f in-us e acciden t informatio n fo r 197 7 an d late r mode l yea r vehicles , NHTSA' s 198 3 Technica l Repor t als o estimate d tha t th e upgrading o f FMVS S 30 1 woul d i n th e lon g termannuall ypreven t 40 0 fatalities , 63 0 injuries , an d 650 0 pos t cras hfires . Thi s indicate s tha t FMVS S 30 1 ha s bee n effectiv e i n substantiall yimproving man yaspect s o f overal l fue l system safet yan

d tha t thes e improvement s wer e purchase d relativel yinexpensively . Th e secon

d are a o f interes t i s th e effec t o f curren t evaporativ e emissio n system s o n potentia l onboar d syste msafet y costs . A s wa s describe d in Sectio n II I o f th e report , an onboard system

i s i n man

yway s an extrapolatio n o f curren t evaporativ e emissio n contro l technolog yan d th e two system s ar e quit e similar . Man yo f th e contro l technique s an d basi c system component s use d woul d b e similar , an d th e same syste man d vehicl e assembl yapproache s coul d b e used . I n fact , man y manufacturer s wil l likel yintegrat e thei r refueling an d fue l tan k evaporativ e contro l systems . Al l curren t .vehicl e fue l system s incorporat e fairl ysophisticate d evaporativ e emissio n contro l systems . Sinc e thes e fue l system s hav e al l bee n designe d t o mee t th e mos t recen t an d mos t stringen t versio n o f FMVS S 30 1 an

d als o provid e a highleve l o f in-us e safet y performance , i t follow s tha t a thoroughevaluatio n o f th e potentia l safet yimplication s o f evaporativ e contro l system s ha s alread

ybee n conducted . Sinc e onboar d system s ar e basicall yextension s o f evaporativ e emissio n systems , clearl y man yo f th e safet ydesign consideration s associate d wit h onboard system s relate d t o passing FMVS S 30 1 or providin g in-us e assuranc e hav e alread ybee n resolve d o r a t leas t addresse d i n evaporativ e emissio n system designs . Consequently , muc ho f th e "groun d work " require d t o insur e onboard safet yha s alread ybee n performed . Therefore , i t i s importan t t o kee p th e magnitud e o f th e onboar d safet ydesig n proces s i n perspective , becaus e clearl ymuc ho f th e safet y technolog

yneede d fo r onboard i s simpl ya n extensio n o f tha t whic halread

yexists . Remembering th e relativel yinexpensiv e an d ye t effectiv e natur e o f curren t fue l systemintegrit ymeasure s an d th e "incremental " natur e o f onboar d safet yi n term s o f th e magnitud e o f th e tas k an d actua l cos t relativ e t o evaporativ e systems , i t i s no wpossibl e t o describ e th e component s whic h facto r int o onboar d safet ycosts . Basically , th e integratio n o f safet yint o a fue l systemincorporating an onboar d control s involve s four type s o f costs . Thes e four cost s ar e fo r 1 ) design an

d developmen t (R&D) , 2 ) specifi c hardware , 3 ) safet y testing , an

d 4 ) weigh t penalt y(or adde d fue l consumption) . Th e paragraph s tha t followdescrib e ho weac ho f th e cos t component s ar e affecte d b yonboar d safety .P.6 7 -65

- T o begi n with , some researc han d developmen t wil l hav e t o b e performe d t o safel yintegrat e onboar d control s int o vehicl e fue l systems . EPAha s estimate d tha t th e tota l design an d developmen t cos t require d t o incorporat e onboar d system s i n vehicl e fue l system s i s abou t $112,00 0 pe r famil yor i n th e rang e o f $0.3 5 t o $0.5 5 pe r vehicl e (passenge r car an d ligh t truck) . Thi s cos t i s for an ydevelopmen t effor t involve d i n combining th e component s o f a n onboar d systemwit hth e res t o f the vehicl e t o for ma uni t tha t interact s safel yan d effectively . Becaus e safet yi s evaluate d inherentl yi n th e design an

d developmen t proces s an d ye t i s onl yon e par t o f th e tota l effort , onl ya fractio n o f th e tota l cos t shoul d b e directl yallocate d t o safety . Also , becaus e muc ho f th e safet y relate d system

developmen t wor k ha s alread ybee n complete d i t i s no t unreasonabl e t o expec t tha t onboar d safet ydevelopmen t cost s woul d onl yb e a smal l fractio n o f th e tota l cos t i n thi s area . I n addition , becaus e o f th e incrementa l natur e o f th e onboard system , muc ho f th e researc han d developmen t tha t wen t int o makin g evaporativ e contro l system s saf e ca n b e applie d directl yt o onboar d controls . Give n tha t manufacturer s ar e designing an onboar d system i n th e contex t o f man yrequirement s an

d certai n desig n feature s serve multipl e functions , i t i s verydifficul t t o isolat e th e leve l o f expenditure s directl yattributabl e t o safety . Fo r thi s analysi s i t wa s assume d tha t abou t 2 0 percen t o f R& D expenditure s relat e t o safety , whic htranslate s t o abou t $0.1 0 pe r vehicle . However , tota l onboar d cos t i s quit e insensitiv e t o thi s assumption , eve n i f th e safet yrelate d developmen t cost s wer e tripled , pe r vehicl e cost s woul d increas e b yonl y on e percent . Th e secon

d componen t o f onboard safet ycost s relate s t o specifi c hardwar e tha t ma yb e require d t o insur e fue l system safety . EPAha s estimate d cost s fo r thre e specifi c items whic h hav e bee n identifie d a s potentia l component s t o b e include d a s par t o f th e onboar d system desig n explicitl yfo r safet y reasons . Thes e thre e items ar e 1 ) a rollove r valve , 2 ) a pressur e relie f mechanism , an d 3 ) fue l systemmodification s necessaryt o safel yincorporat e a rollove r valve , pressur e relie f mechanism , o r othe r onboar d hardware . EP Aha s estimate d th e cos t o f a solenoi d rollove r valv e (lik e th e on e show n i n Figure s 1 9 an

d 20 ) t o b e $4.60 . [17 ] Thi s pric e include d th e cos t o f th e valve , an actuato r locate d a t th e fillcap , an d th e necessarywirin g an d connectors . Manufacturer s estimat e th e cos t o f a valv e assembl ysimila r t o tha t describe d b yEPA' s cos t estimat e woul d b e i n th e rang e o f $5.0 0 t o $6.00 . I t shoul d b e note d tha t thes e estimate s ar e fo r th e mos t comple x rollove r valv e type , an d tha t th e cos t o f a simple r valv e assembl ysuc ha s th e fillnec k mounte d typ e (se e Figure s 9-15 ) i s estimate d t o b e mor e i n th e $3.0 0 t o $4.0 0 range . Th e availabl e informatio n indicate s tha t a n appropriat e rollove r valv e cos t fall s int o a rang e o f $3.0 0 t o $6.00 .P.6 8
-66

- Th e secon

d safet yhardwar e cos t i s fo r a pressur e relie f mechanism . Thi s mechanis mwoul d onl yb e neede d fo r onboar d system s incorporating a mechanica l fillnec k seal , an d consequentl yno t al l vehicle s woul d requir e it s use . However , fo r thos e system s tha t woul d requir e a pressur e relie f mechanism , EPAha s estimate d tha t thi s devic e woul d increas e system cost s b

yapproximatel y$0.50 . Thi s estimat e i s base d o n pressur e relie f mechanism s currentl yuse d i n automotiv e application s whic hperformth e sam e basi c functio n an d ar e simila r i n complexity.[36 ] Th e fina l onboard safet yhardwar e cos t account s fo r an y fue l systemmodification s tha t woul d b e necessaryi n orde r t o safel yaccommodat e an yonboar d contro l hardware . Fo r example , a vehicle' s fue l tan k or fillpip e migh t hav e t o b e re-shape d o r modifie d i n orde r t o accep t a rollove r valve . Also , for safet y reasons , some sligh t re-routing o f th e fue l system' s vapo r line s mayb e required . EPAha s estimate d a total

- modificatio n cos t t o b e $0.5 0 pe r vehicle . Onl ypar t o f thi s tota l cos t woul d b e require d fo r safet ypurposes . However , becaus e safet y inherentl yenter s int o th e decisio n t o mak e an ymodifications , i t i s difficul t t o acces s wha t par t o f th e tota l modificatio n cos t shoul d b e allocate d t o safety ; perhap s hal f o r mor e ($0.2 5 t o $0.3 0 pe r vehicle ) coul d b e considere d a s drive n b ysafet y relate d concerns . Summing up th e thre e individua l safet yhardwar e cost s yield s a tota l estimate d figur e i n th e rang e o f $3.2 5 t o $6.80 . However , thi s cos t estimat e doe s no t includ e manufacture r overhea d an d profit . I n orde r t o obtai n th e retai l pric e equivalen t cost , thes e estimate s mus t b e multiplie d b

ya marku

p factor . Presently , a markup facto r valu e o f 1.2 6 appear s representative.[37 ] Therefore , afte r inclusio n o f th e marku p factor , a tota l retai l pric e equivalen t safety-relate d hardwar e cos t fall s withi n th e rang e o f $4.1 0 t o $8.60 . Th e third componen t o f safet ycost s account s fo r an y safet ycras htesting tha t woul d b e necessary . EP Aha s estimate d th e cos t o f FMVS S 30 1 cras htesting t o assur e fue l systemintegrit yfo r onboar d system s t o b e abou t $34,00 0 pe r bodyline/styl e o r abou t $0.1 2 pe r vehicle.[38 ] Thi s estimat e i s base d o n four test s fo r FMVS S 30 1 onl yrequire d pe r bod y line/styl e wit htwo vehicle s require d fo r eac hsequenc e o f four tests . Clearl ysafet ycras htes t cost s ar e veryminima l i n th e lon g term an d d o no t pos e a

n obstacl e t o th e adoptio n o f onboar d controls . I n some case s thes e cost s ma yb e highe r bu t eve n i f tota l cost s wer e doubl e th e estimate , th e overal l pe r vehicl e cos t woul d ris e b yles s than on e percent . Also , cost s coul d b e lowe r i f FMVS S 30 1 tes t wer e combine d wit hcras h testing require d fo r complianc e wit hothe r safet ystandards .P.6 9 -67

- Th e fourt hcomponen t o f safet ycost s i s th e estimat e o f th e added fue l consume d ove r th e lif e o f th e vehicl e du e t o th e increas e i n vehicl e weigh t resulting fro madde d safet y hardware . Th e amoun t o f weigh t adde d t o a vehicl e fo r a rollove r valv e an

d pressur e relie f mechanis m i s ver ysmal l (0. 4 lbs) , an

d EP Aestimate s tha t onl yabou t $0.2 5 i n adde d fue l cost s wil l resul t fro mthei r inclusio n int o th e onboar d system.[17 ] Atota l onboar d safet ycos t i s calculate d b ysumming al l fou r individua l componen t costs . Tota l capita l cost s pe r famil yaverag e abou t $56,000 . Th e pe r vehicl e safety-relate d cost s rang e fro

m$4.5 0 t o $9.00 , o r abou t 2 5 percen t o f EPA' s estimat e o f th e tota l cost , depending o n th e typ e o f rollove r valv e used . On e fina l poin t need s t o b e mad e wit hregar d t o thes e safet ycos t estimates . T o th e degre e tha t manufacturer s tak e th e opportunit yintroduce d b ya n onboar d requiremen t t o furthe r reduc e in-us e ris k beyond tha t no waccepte d wit hpresen t systems , som e additiona l cost s migh t b e involve d whic hhav e no t bee n identifie d or quantified . O n a fleetwid e basi s thes e woul d b e quit e small . Also , i t shoul d b e note d tha t th e adde d benefit s o f thes e measure s hav e no t bee n include d either . EPAestimate s safet yrelate d onboar d cost s t o b e $4.50-9.0 0 pe r vehicle . Whil e ther e i s some uncertaint yi n th e developmen t cos t portio n o f th e estimate , th e tota l rang e show n her e i s quit e insensitiv e t o an yerror . Thes e cost s ar e quit e simila r t o thos e previousl yincurre d b ymanufacturer s t o insur e fue l systemsafety . Man yo f th e potentia l problem s relate d t o implementing onboar d system s safel yhav e alread ybee n considere d i n th e desig n an d developmen t o f presen t evaporativ e systems . Th e manufacturer s previou s experienc e i n implementing evaporativ e system s safel yan d th e incrementa l natur e o f onboard system s reduce s cost s an d th e leve l o f potentia l problems . Thi s analysi s demonstrate s tha t highlevel s o f in-us e fue l systemsafet ycan b e achieve d a t lowcost , an d ther e i s n o nee d fo r a manufacture r t o "cu t corners " o n onboar d safet yt o reduc e costs . B . Leadtime I f EP Awer e t o implemen t an onboar d requirement , i t woul d b e necessaryt o allo wa sufficien t perio d o f leadtime betwee n th e dat e th e rul e i s promulgate d an d th e mode l yea r th e system s ar e t o b e require d o n productio n vehicles . Thi s leadtime i s provide d s o tha t manufacturer s wil l b e abl e t o adequatel y prepar e fo r th e requiremen t throughsystemdesign , development , testing , tooling , certification , an d safet yevaluation . Som e o f th e task s involve d i n th e preparatio n proces s coul d b e worke d o n simultaneously , whil e some task s canno t begi n befor e other s ar e complete . Whil e EPAestimate s tha t non e o f th eP.7 0

-68

- individua l task s requir e mor e than twelv e month s t o complete , du e t o th e sequentia l natur e o f some o f th e tasks , a leadtime perio d o f approximatel y2 4 month s wil l b e require d b y manufacturers . Figur e 2 3 show s howth e individua l leadtime component s resul t i n a tota l estimat e o f 2 4 months . First , four t o si x month s ar e include d fo r manufacturer s t o develo p an d optimiz e working prototyp e system s applicabl e t o al l o f thei r differen t vehicl e models . Thi s i s no t a t al l unreasonabl e give n th e fac t tha t working prototype s alread yexis t an

d man ymanufacturer s hav e evaluate d thes e or thei r ow n prototyp e t o some degree . No t al l manufacturer s hav e develope d working prototyp e onboar d systems , bu t th e technolog yrequire d t o develo p suc hsystem s i s readil yavailabl e an d in-dept htechnica l description s o f suc h system s hav e bee n describe d in publicl yavailabl e literature . Four t o si xmonth s shoul d b e adequat e time for thes e manufacturer s t o develop an d evaluat e prototyp e systems . Onc e th e prototyp e developmen t i s complete , initia l durabilit ytesting o f th e prototyp e coul d b e conducte d unde r laborator

yconditions . Thi s laboratorytesting i s no t expecte d t o las t mor e than two months . Following laboratorytesting , thre e separat e action s ca n begi n simultaneously . Thes e thre e task s are : I ) in-vehicl e testing , 2 ) safet yoptimization , an d 3 ) tooling an

d prov e ou t o f th e overal l contro l systemthroughefficienc yan d durabilit y verification . Simila r in-vehicl e testing program s hav e require d four t o si xmonth s for completion . Safet yevaluatio n i s th e secon

d tas k whic hcoul d begi n subsequen t t o th e completio n o f th e prototyp e laboratorytesting . Safet y evaluatio n woul d involve th e us e o f compute r cras hsimulatio n model s an

d vehicl e cras htesting (four test s pe r bod y line/style ) t o verif yth e crashworthines s o f th e vehicle' s modifie d fue l system . Becaus e thi s evaluatio n coul d begi n immediatel yafte r th e completio n o f laboratorytesting , a ful l 1 4 month s o f leadtime woul d b e availabl e t o manufacturer s i f neede d t o performthi s task . Base d o n discussion s wit hNHTSA , 6 month s i s normall yenoughtim e t o complet e a safet y evaluation . Therefore , 1 4 month s appear s mor e than adequat e t o perfor mth e necessarysafet yoptimizatio n an d testing fo r a manufacturer' s produc t line . Tooling coul d als o begi n onc e laborator

ytesting i s complete . Figur e 2 3 show s EPA' s estimat e tha t tooling coul d requir e a s littl e a s 3 month s an d a s muc ha s 1 2 month s depending o n th e magnitud e o f th e task . Differen t factor s ar e weighe d befor e a manufacture r commit s t o variou s tooling changes . Manufacturer s ca n commi t t o some toolin g change s fo r onboard control s immediatel yafte r th e in-vehicl e testing (e.g. , purg e valves) , wherea s the yma ychoos e t o wai t unti l afte r safet yanalysi s befor e committing t o othe r tooling change s (e.g. , rollove r valves) . However , i n an overal l sense , 1 2 month s woul d provid e manufacturer s wit henoughtime t o delay som e tooling change s an d stil l complet e th e tas k wel l withi n the 24-mont hleadtime .

# Safety-upto1 4 MO .

Tooling : Mit. t- 8 no . CHIT. 3- 4 NO

. IIIIIIIIIMIIIIIIIIl )

lllllllllllllllllll l iiimi m HIIIHM * lllllllllllllllllll l It.Hl.M>*<>**..>l i



# Certificatio n10-1 2MO

. ii i

IWUMIUMUUM J

»••» » m HtMMM.IMI M 1**11*.KM . 

# Developnent ; r^ototup eHNO. U b 2 MD

. 

# IHelilcl e4-6 no. 1 as <ss l

I I L J I L-J— L !__ J I L i _ J I l_ L 

# FR H 4 8 

# 1 2

Honth s 1 6 2 0 2 4

•••11.1.11*1111 1 

# hi\tttisclwiulin gfliuililit y



# FIGUR E2 3 ONBOARD,LEADTIMEP.7 2 -70

- Th e onl yothe r proces s whic hrequire s completio n withi n the 24-mont hleadtime perio d i s emission s certification . EPA ha s foun

d fro mpas t experienc e tha t a manufacture r normall y require s betwee n 1 0 t o 1 2 month s t o certif yit s produc t line.[39 ] Thi s estimat e i s base d o n a 1 0 mont hengin e famil y certificatio n schedul e whic hallow s time fo r durability , emission data , fue l economy , an d confirmatorytesting . Becaus e certificatio n canno t begi n prio r t o th e completio n o f in-vehicl e testing , certificatio n i s critica l path , an d EPA estimate s a tota l leadtime perio d o f 2 4 month s wil l b e neede d overall . Twenty-fou r month s o f leadtime i s quit e reasonable , especiall ysinc e mos t o f th e fundamenta l developmen t wor k i s alread ycomplete . Onboar d systemprototype s ar e presentl y available , an

d man yaspect s o f th e system' s performanc e hav e alread ybee n teste d an

d prove n t o b e effective . Also , becaus e onboard contro l technolog yi s incrementa l in

- natur e t o evaporativ e emissio n controls , ther e i s n o nee d to
- design an

d develop entirel yne wsystems . A s a matte r o f fact , man yo f th e critica l onboar d design issue s hav e alread ybee n incorporate d int o curren t fue l systemdesign s wit hth e inclusio n o f evaporativ e emissio n contro l systems . Fo r example , evaporativ e emissio n contro l system s hav e alread yadde d th e following t o fue l systems : vapo r ven t lines , vapo r storag e device , caniste r purg e capability , an d corresponding safet yprovision s associate d wit heac ho f thes e additions . Sinc e muc ho f th e developmen t wor k i s alread ycomplete , implementing onboar d systems shoul d b e n o mor e o f a problem t o vehicl e manufacturer s than wa s implementing evaporativ e emissio n contro l systems . EPA' s 24-mont hleadtime estimat e i s supporte d b ypas t experienc e wit hthre e previou s evaporativ e emissio n rulemakings . Thes e rulemaking s include d th e origina l 197 8 6. 0 g/tes t LDV/LD T evaporativ e emissio n standar d whic hwa s implemente d wit hjus t 1 2 month s o f leadtime , th e 198 1 2. 0 g/tes t LDV/LD T evaporativ e emissio n standar d whic hwa s implemente d wit h2 4 month s o f leadtime , an d th e 198 5 HDG

V evaporativ e standar d whic hwa s implemente d wit h2 4 month s o f leadtime . I n eac ho f thes e thre e rulemakings , manufacturer s face d leadtime factor s identica l t o th e one s tha t woul d accompan

yan onboar d requirement , including safety . Sinc e manufacturer s wer e abl e t o safel yan d effectivel yintegrat e evaporativ e emissio n control s int o thei r vehicles ' fue l system s wit h2 4 month s o f leadtime , an d sinc e th e magnitud e o f th e onboard implementatio n tas k i s similar , thi s suggest s tha t manufacturer s shoul d als o b e abl e t o safel yan d effectivel y integrat e onboar d int o vehicl e fue l system s wit h2 4 month s o f leadtime . A s far a s safet ydevelopmen t an d evaluatio n i s concerned , EPA' s leadtime estimat e i s als o supporte d b yth e pas t experienc e o f NHTS Ai n implementing th e variou s version s o f-71

-

FMVS S 301 . Tabl e 4 show s th e chronologica l historyo f FMVS S 301 . Th e origina l 196 8 FMVS S 30 1 applicabl e t o passenge r car s wa s implemente d wit hles s than 1 2 month s o f leadtime . Whe n th e standard wa s revise d fo r 197 6 mode l yea r passenge r cars , 1 7 month s o f leadtime wa s provided . Fo r 197 7 mode l yea r passenge r cars , manufacturer s had t o conten d wit hth e mos t substantia l upgrad e t o th e standard , an d thi s wa s accomplishe d wit honl y2 9 month s o f leadtime , an d onl y1 2 month s betwee n ne w requirements . Also , beginning i n th e 197 7 mode l year , FMVS S 30 1 wa s extende d t o includ e ligh t trucks . Thi s extensio n involved a 29-mont hleadtime perio d wit hfurthe r cras h requirement s i n effec t 1 2 month s later , thu s requiring recertification . Finally , i n 1977 , FMVS S 30 1 wa s extende d t o includ e schoo l buse s (wit ha GVW R greate r tha n 10,00 0 lbs) , an d thi s requiremen t wa s implemente d wit h1 7 month s o f leadtime . Thi s experienc e indicate s tha t 2 4 month s o f leadtime allow s manufacturer s sufficien t time t o facto r in safety . Base d o n th e informatio n provide d above , 2 4 month s appear s t o b e adequat e time t o implemen t onboard controls , wit hful l consideratio n o f al l safet yconcerns . Becaus e safet y evaluatio n ca n procee d i n paralle l t o thre e othe r tasks , mor e than a yea r i s availabl e fo r compute r simulatio n an d actua l safet ycras htesting . Thi s allow s adequat e leadtime t o properl yintegrat e safet yint o onboar d system s especiall ysinc e manufacturer s can utiliz e an d expan d safet ytechnologyuse d i n curren t evaporativ e emissio n contro l system s t o develo p effectiv e onboar d systems . Also , muc ho f th e safet y developmen t whic hwoul d b e require d ha s alread ytake n plac e wit hth e identificatio n an d resolutio n o f suc hpotentia l safet y issue s a s rollove r protectio n an d fue l tank pressur e relief . Consequently , a 24-mont hleadtime perio d woul d provid e manufacturer s wit hsufficien t opportunit yt o develo p saf e an d effectiv e onboar d systems . Whil e thi s analysi s indicate s tha t th e curren t leadtime estimat e o f 2 4 month s i s reasonabl e fo r mos t i f no t al l vehicl e models , EPAi s sensitiv e t o manufacturer s concern s regarding leadtime requirements . Publi c comment s regarding EPA' s 24-mont hleadtime estimat e wer e submitte d a s par t o f comment s o n EPA' s origina l Gasolin e Marketing Stud y(Jul y1984).[40 ] Whil e mos t commenter s di d no t objec t t o th e 24-mont hleadtime estimat e presente d i n th e Gasolin e Marketin g Study , aut o manufacturer s fel t tha t a 24-mont hleadtime wa s insufficien t t o implemen t onboar d controls . Th e leadtime period s suggeste d b y thes e commenter s range d fro mthre e t o si xyears . Thos e commenter s suggesting tha t four o r mor e year s woul d b e necessaryals o suggeste d tha t onboar d control s shoul d b e phased-i n graduall ya s norma l vehicl e mode l redesign an d turnove r occurs . Using thi s approach , implementing onboar d control s woul d b e les s burdensome an d woul d allo wextr a tim e t o dea l wit himplementatio n or packaging problem s o n uniqu e vehicles . However , i t i s wort hnoting tha t comment s receive dP.7 4
-72

-

Mode l Yea r Requiremen t 1968[1 ] 1976[2 ] 1977[2 ] 1977(2 ] 1978[2 ] 1977 [2 ] 1978[2 ] 1977[3 ] •

Vehicl e Typ e P C P C P C Clas s 1 LD T Clas s 1 LD T Clas s 2 LD T Clas s 2 LD T Schoo l Buse s Chronoloqyo f

Promulgatio n Dat e 2-3-6 7 3-21-7 4 3-21-7 4 3-21-7 4 3-21-7 4 3-21-7 4 3-21-7 4 10-15-7 5 Tabl e 4

FMVS S 30 1 Reo u Effectiv e Dat e 1-1-6 8 9-1-7 5 9-1-7 6 9-1-7 6 9-1-7 7 9-1-7 6 9-1-7 7 4-1-7 7 irement s

Leadtim e (Months ) 1 1 1 7 2 9 2 9 4 1 2 9 4 1 1 7 Tim e Sinc e

Las t Requirement s

1 2/ 3 yrs . 1 2 mos .

1 2 mos .

1 2 mos .

[1 ] Moto r Vehicl e Safet yStandar d No . 301 , Fue l Tanks , Fue l Tan k Fille r Pipes , an d Fue l Tan k Connection s - Passenge r Cars ; 3 2 F R 2416 , Februar y3 , 1967 , Par t 571 ; S 301-1 . [2 ] Federa l Moto r Vehicl e Safet yStandar d No . 301 , Fue l Syste m Integrity , 3 9 F R 10588 , Marc h21 , 1974 . [3 ] Federa l Moto r Vehicl e Safet yStandar d No . 301 , Fue l Syste m Integrity , 4 0 F R 48352 , Octobe r 1 5 1975 .-73

-

fro mth e manufacturer s suggesting th e nee d fo r a longe r leadtim e wer e no t supporte d wit han ycompelling argument s whic h woul d substantiat e th e insufficiencyo f a 24-mont hleadtime . Whil e th e analysi s above indicate s tha t approximatel y2 4 month s o f leadtime shoul d b e sufficient , ther e ar e some factor s whic hmus t b e considere d bu t ar e difficul t t o facto r int o th e analysis . First , a s wa s mentione d above , some manufacturer s hav e no t develope d working onboard prototype s du e t o resourc e o r facilit yconstraint s an d th e possibilit yexist s tha t thes e manufacturer s wil l tak e n o definitiv e actio n o n system s developmen t prio r t o a fina l actio n b yEPA . Some hav e commente d tha t thes e manufacturer s shoul d no t b e penalize d becaus e o f thi s an d mayrequir e a greate r amoun t o f leadtime . Second , vehicle s wit hatypica l dut ycycle s (ambulances , mai l trucks , etc. ) mayrequir e mor e leadtime t o implemen t onboar d control s safely . Vehicle s assemble d b ysecondarymanufacturer s suc ha s recreationa l vehicle s an d airpor t mini-buse s coul d als o requir e mor e time especiall yi f adding an onboar d system require s othe r vehicl e changes . Finally , mor e leadtime ma yb e necessarybecaus e manufacturer s mayno t hav e th e tes t facilit y an d safet yengineering resource s t o effectivel ycompl ywit h multipl e vehicl e safet ystandard requirement s concurrently . A simila r concer n ma yexis t fo r emission s recertificatio n sinc e manufacturer s woul d i n mos t case s hav e t o recertif yvirtuall y al l gasolin e powere d vehicle s fo r exhaus t an d evaporativ e emission s i n additio n t o th e ne wrefueling requirement . Becaus e o f thes e concerns , mor e leadtime mayb e necessaryfo r th e implementatio n o f saf e onboar d contro l systems . EPAi s committe d t o providing manufacturer s th e leadtime necessaryt o implemen t onboard control s safel yan d effectively . Consequently , EPAi s ope n t o considerin g th e nee d fo r mor e leadtime and/o r a shor t phase-i n perio d fo r onboar d controls . Suc ha phase-i n perio d woul d provid e manufacturer s wit hadditiona l time t o solve an yonboar d systempackagin g an d testing problem s fo r uniqu e vehicl e models . Also , i f a manufacture r had uniqu e safet yconcern s o n on e o r tw o bod y lines/styles , thi s approac hwoul d offe r a manufacture r mor e leadtime t o properl yaddres s them . I n addition , i t coul d improve th e cos t efficienc yo f control s b yallowing manufacturer s t o foreg o developmen t o f onboar d system s fo r vehicl e model s schedule d fo r retiremen t o r permi t manufacturer s othe r flexibilitie s wit hne wmodel s being planne d an d thos e no w i n production . Th e implementatio n o f othe r uniqu e contro l strategies , suc ha s bladde r systems , woul d requir e mor e leadtime . I t i s als o importan t t o not e tha t i f onboar d control s ar e required , th e dat e o f promulgatio n o f th e fina l rul e ma yb e suc htha t mor e than 24-month s leadtime i s actuall yavailable . Th e mode l yea r generall ybegin s i n Septembe r o r October . I f th e publicatio n o f th e fina l rule , i s muc hbeyond tha t period ,P.7 6 -74

- th e manufacturer s woul d hav e th e remainde r o f tha t mode l yea r i n additio n t o th e 2 4 month s discusse d previously . Therefore , i n actualit ymanufacturer s coul d hav e substantiall ymor e than 2 4 months , bu t EPA' s analysi s indicate s tha t onl y2 4 month s i s needed . I n conclusion , give n th e magnitud e o f th e task , thi s analysi s indicate s tha t 2 4 month s o f leadtime i s adequat e t o allowmanufacturer s t o safel yan d effectivel yimplemen t onboar d controls . Thi s estimat e i s supporte d b yEPA' s experienc e wit h implementing evaporativ e emissio n standard s an d NHTSA' s experienc e wit himplementing th e variou s version s o f FMVS S 301 . However , EP Ai s committe d t o providing th e leadtime necessaryt o implemen t onboard control s bot hsafel yan d effectively . Thu s EPAi s ope n t o considering mor e leadtime and/o r a shor t phase-i n perio d or othe r approache s whic har e pertinent . Up t o thi s point , thi s repor t ha s addresse d onboard safet y issue s fro

mprimaril ya passenge r car an d ligh t truc k poin t o f view . I t shoul d b e note d howeve r tha t jus t a s evaporativ e emissio n contro l technolog ywa s extende d t o heavy-dut ygasolin e fuele d vehicle s (HDGVs) , onboard contro l technolog ycoul d als o b e applie d t o HDGVs . Whil e man yo f th e safet yissue s discusse d thu s far woul d b e identica l i n a n HDG V application , some aspect s o f HDG

V onboard safet ywoul d b e distinc t from light-dut yissues . Th e nex t sectio n i n thi s repor t ha s bee n include d t o addres s th e similaritie s an d difference s betwee n heavy-dut yan

d light-dut yonboard safet yissues . VII . Heavy-Dut yGasolin e Vehicl e Requirement s Sinc e an EPAonboard refueling contro l requiremen t woul d cove r heavy-dut ygasolin e vehicle s (HDGVs) , i n additio n t o passenge r car s an d ligh t trucks , i t i s importan t t o evaluat e an ypotentia l HDG

V onboard syste

msafet yconsideration s a s wel l a s thos e encountere d in light-dut yapplications . (I t i s importan t t o not e tha t a n onboard requiremen t wil l no t appl yt o heavy-dut ydiese l truck s an d buses. ) Whil e non e o f th e comment s receive d regarding th e safet yimplication s o f onboar d specificall yaddresse d HDGVs , overal l light-dut yconcern s discusse d earlie r ar e expecte d t o apply . However , i t i s importan t t o not e tha t HDG V fue l systemconfiguration s diffe r somewha t fromthos e foun d o n passenge r car s an d ligh t trucks , an d th e fue l systemsafet yrequirement s als o differ . Thi s sectio n o f th e repor t identifie s distinc t HDG V onboar d safet yissue s an d discusse s th e implication s thes e distinction s coul d hav e o n manufacturer s fue l systemsafet y designs . I t begin s wit ha brie f descriptio n o f some o f th e mor e commo n HDG

V configurations . Following thes e descriptions , a discussio n o f th e HDG V fue l systemsafet ystandard s wil l b e presented , an

d difference s betwee n light

- an d heavy-dut y vehicl e onboar d system s du e t o fue l system configuration s an d-75

-

safetytes t requirement s wil l b e discussed . Next , HDG V onboard safetyissue s wil l b e introduce d an d analyzed . Finally , thi s sectio n wil l en

d wit ha brie f segmen t concerning th e effec t o f HDG V onboard safet yo n cost s an d leadtime . Befor e beginning thi s analysi s on e ke yclarificatio n i s needed . FMVS S 30 1 cover s al l vehicle s wit ha gros s vehicl e weigh t rating (GVWR ) o f 10,00 0 lbs o r les s (plu s schoo l buse s ove r 10,00 0 lb s GVWR) . Fo r emissio n contro l purpose s EPA classifie s al l gasoline-powere d vehicle s wit ha GVW R o f 8,50 1 lb s or mor e a s HDGVs . Ou t o f EPA' s HDG V categoryonl y90,00 0 vehicle s (or approximatel y2 5 percent ) hav e a GVW R greate r tha n 10,00 0 lbs . Thu s mos t (or approximatel y7 5 percent ) o f EPA' s HDG V clas s (thos e vehicle s wit ha GVW R betwee n 8,50 1 an d 10,00 0 lbs-Clas s lib ) i s covere d b yth e LDT requirement s i n FMVS S 301 . Sinc e th e fue l system s o n Clas s li bHDGV s ar e essentiall y identica l t o thos e o n lighte r weigh t LDTs , an d FMVS S cover s al l LDT s up t o 10,00 0 lb s GVWR , th e previou s portio n o f thi s analysi s applie s t o th e Clas s li bHDGVs . Th e remainde r o f thi s analysi s wil l focu s o n gasoline-powere d vehicle s whos e GVWR exceed s 10,00 0 lbs . Thi s analysi s addresse s complianc e cost s wit hth e assumptio n tha t HDG V manufacturer s wil l us e onl ycertifie d fue l tank s o n thei r vehicles . Currently , i t i s th e owner' s responsibilit yt o purchas e an d us e a certifie d tank i f require d byregulation . Th e curren t Moto r Carrie r Safet yRegulation s exempt s a vehicl e o r drive r use d entirel ywithi n a municipalit y o r commercia l zone , althoughtheymayvoluntaril ycompl ywit h th e regulations . Thes e regulation s mayb e change d i n th e futur e t o b e applicabl e t o al l HDGV s an d eliminat e th e aforementione d commercia l zon e exemption . Therefore , thi s analysi s assume s tha t al l HDGV s wil l us e fue l tank s certifie d t o compl ywit hth e regulation s discusse d below . A . HDG

V Fue l SystemConfiguration s Jus t a s ther e ar e chassi s an d drivetrai n difference s betwee n heav

yan d light-dut yvehicles , ther e ar e als o some difference s i n thei r fue l system configurations . Fue l tank s ar e generall yo f a heavie r constructio n an d ar e large r i n volume ; dua l fue l tank s ar e als o mor e common . Fue l tank shape s varysomewha t a s doe s th e locatio n o f th e tank s o n th e vehicle . Also , i t i s ofte n th e cas e tha t th e fillpip e i s integra l wit hth e fue l tank , o r ha s a verylimite d lengt ha s compare d t o lighte r weigh t vehicles . A s a par t o f a recen t contrac t study , EP Asurveye d th e characteristic s o f the fuel/vapo r handling system s o f HDGV s over ' 10,00 0 lb s GVWR . [41 ] Th e keyresult s o f th e surve y portio n o f tha t repor t ar e summarize d i n Tabl e 5 , whic hwil l serv e a s th e basi s fo r th e remainde r o f thi s discussion .Tabl e 5

Selecte d Characteristic s o f Heavy-Dut yGasolin e Vehicl e Fuel/Vapo r Handlin g System s b yVehicl e Model/Serie s

Manufacture r GM Mode l o r

Serie s P4T04 2
P6T04 2 Fue l Tan k Shap e

Rectangula r Rectangula r Fue l Tan k Locatio n 3 0 gal . Moun t O n Righ t Hand Fram e 3 0 an d 6 0 gal . Mounte d o n Lef t Han d Fram e Numbe r o f Canister s Siz e o f

Canister s 150 0 and 250 0 c c 150 0 and 250 0 c c Diamete r

o f Ven t Line s Diamete r

o f Purg e Line s 0.31 2 in . 0.37 5 in . 0J31 2 in . 0.37 5 in . C5D04 2 Rectangula r an d

Rectangula r Ste p

C6D04 2 Rectangula r an d C7D04 2 Rectangula r Ste p C7D06 4

B6P04 2 Rectangula r 2 0 gal . Mounte d Righ t Hand Fram e 5 0 gal . Ste p Mounte d Righ t o r Lef t Han d Fram e 2 0 gal . Mounte d Righ t Hand Fram e 5 0 gal . Ste p Mounte d Righ t o r Lef t Han d Fram e Dua l 5 0 gal . Ste p Mounte d Lef t an d Righ t Hand Fram e 3 0 gal . Mounte d Righ t Hand Fram e 150 0 and 250 0 c c 0.31 2 in . 0.37 5 in .

150 0 and 250 0 c c

150 0 an d 250 0 c c 0.31 2 in . 0.37 5 in . | as I

0.31 2 in . 0.37 5 in .

FORD F-Serie s Rectangula r

B-Serie s Rectangula r C-Serie s D-Typ e 6 0 gal . Mounte d Righ t Hand Fram e 3 5 gal . Righ t Han d Sid e Fram e Mounte d 3 0 gal . Righ t Han d Sid e Fram e Mounte d 5 0 gal . Righ t Han d Sid e Fram e Mounte d 140 0 ml . ea . 140 0 ml . ea . 140 0 ml . ea . 3/ 8 in . 3/ 8 in .

3/ 8 in . 3/ 8 in . 3/ 8 in .

3/ 8 in .P.7 9
-77

- First , a s can b e see n i n Tabl e 5 , ther e ar e onl ytwo manufacturer s whic hmarke t HDGVs . Betwee n themthe yoffe r onl y abou t 1 0 differen t chassi s model s t o whic han ynumbe r o f differen t bodie s or payload s can b e attache d (tanks , dumps , carg o boxes , moto r homes , schoo l buses , fla t beds , etc) . Th e secon

d are a o f interes t i s th e fue l tanks . Essentiall ythre e differen t tank s shape s ar e used : standar d rectangular , step rectangular , an d D-shape . Example s o f thes e tank s ar e show

n i n Figur e 24 . Th e tan k volume s rang e from2 0 gallon s t o 6 0 gallons , wit han averag e i n th e rang e o f 3 5 t o 4 0 gallon s for singl e tan k HDGV s an

d 7 5 gallon s fo r dual-tank HDGVs . EPAestimate s tha t abou t 1 5 percen t o f HDGV s us e dua l tanks , wit hmos t o f thos e being i n heavie r weigh t truck s (>20,00 0 lb s GVWR).[17 ] Mos t passenge r ca r an d ligh t truc k fue l tank s ar e located unde r th e vehicl e bod yan d thi s i s als o th e cas e for some HDG V configuration s (e.g. , schoo l buses) . However , o n some HDG V configurations , th e fue l tank s ar e mounte d o n th e oute r sid e o f th e vehicl e frame (righ t o r lef t han d sid e fo r singl e tanks , bot hside s fo r dua l tanks ) an d ar e expose d t o th e roa d rathe r than shielde d b yth e vehicl e body . A s wa s allude d t o above , mos t HDG V tank s hav e onl ya limite d fillpip e lengt h(<8" ) an d some hav e essentiall ynon e a t all , wit hth e fue l cap being integra l t o th e tank . Finally , wit hregard t o th e HDG V evaporativ e emissio n systems two observation s ar e important . (Se e Figur e 2 5 fo r an exampl e o f a HDG

V evaporativ e system. ) First , fo r th e same reason s a s describe d for passenge r car s an d ligh t trucks , HDGV s us e a limiting orific e i n th e evaporativ e emissio n system . Second , th e tota l evaporativ e emissio n caniste r capacit yo n an HDG V i s mor e tha n twic e th e averag e o n passenge r car s an d LDT s (2.8-4. 0 liters) . However , o n HDGV s diurna l emission s fromth e fue l tan

k an d ho t soak emission s fro mth e fue l meterin g system ar e route d t o differen t canisters . Ho t soak emission s ar e somewha t mor e o f a concer n o n HDGV s becaus e presentl ymos t ar e carburete d rathe r than fue l injected . T o th e degre e tha t HDG V engine s fue l system s ar e converte d fro m carburete d t o fue l injecte d a s i s no wprojected , concern s ove r ho t soak emission s maydiminis han

d allowth e eliminatio n o f th e second caniste r o n thos e vehicles.[42,43 ] Wit hthi s brie f background o n HDG V fuel/evaporativ e system s w e tur n no wt o a discussio n o f th e fue l systemsafet y standard s whic happl yt o HDGV s ove r 10,00 0 lb s GVWR . B . HDG

V Fue l SystemSafet yStandard s Fue l system

safet yregulation s diffe r according t o vehicl e an d fue l system

configuration . Th e Departmen t o f Transportation/Offic e o f Moto r Carrie r Safet y(OMCS ) ha s requirement s whic happl yt o al l HDGV s ove r 10,00 0 lb s GVWR . I n addition , schoo l buse s mus t mee t th e requirement s prescribe d specificall yi n FMVS S 301 . Th e OMC S an d FMVS S 30 1 requirement s ar e summarize d below .P.8 0
-78

- Figur e 2 4

HDG V Fue l Tank s

D-Shap e

Standar d Rectangula r

/ &

Ste p Rectangula rFigur e 2 5 TYPICA L HDGV

EVAPORATIV E SYSTE M

ir »

-BAL L CHEC K VALV E TAN K RESTRICTO R PRESSURE/VACUUM RELIE F

SEALE D A GA S CAP- ' 

# L3/16 " DIA ~13 ' LON

G 

# i<r PURG E VALV E 

### 5LJ c t -3/8 " DI A ~ 3 ' LON

G 

## =cxj =

2 . 5 LITE R CANISTE R

3 0 GALLO

NFUE LTAN K 

# i TO PURG E INDUCTION POIN T so

I

T l 0 0P.8 2 -80

- 1 . Offic e o f Moto r Carrie r Safet yRequirement s OMC S safet yregulation s includ e bot hspecifi c desig n requirement s an

d actua l fue l tank safet ytests.[44 ] Th e desig n requirement s contai n rule s governing th e location , installation , an

d constructio n o f fue l tank s use d o n HDGVs . Also , fue l lines , fittings , an d fillpipe s mus t conformt o certai n requirements . Th e actua l testing requirement s depen d o n whethe r a fue l tan k i s side-mounte d or non-sid e mounted . T o paraphras e th e definition , a truc k fue l tan k i s considere d sid e mounte d i f i t extend s beyon

d the outboard sid e o f a fron t tir e positione d i n the straigh t ahead position . Thi s i s show n pictoriall yi n Figur e 26 . An

yfue l tan

k whic hdoe s no t hav e thi s characteristi c i s considere d non-sid e mounted , an d in thi s analysi s wil l b e referre d t o a s frame mounted . Th e testing requirement s fo r frame-mounte d tank s wil l b e discusse d first . Aframe mounte d HDG V fue l tan

k ha s t o b e abl e t o pas s two fue l tan

k safet ytests . Th e firs t o f thes e two tests , th e safetyventing systemtest , involve s applying an envelopin g flam e t o an inverte d fue l tank t o insur e tha t th e fue l tank' s safet yventing systemactivate s prio r t o th e tank' s interna l pressur e exceeding fift ypound s pe r squar e inch . Th e second fue l tan

k safet ytes t i s a leakag e tes t whic hinvolve s filling the tan k t o capacit yan

d rotating th e tank througha n angl e o f 150 ° i n an

ydirectio n fro

mit s norma l positio n t o insur e tha t neithe r th e tan

k no r an

yfitting lea

k mor e tha n on e ounc e o f fue l pe r minut e i n an ypositio n th e tank assume s during th e test .HDGV s wit hsid e mounte d fue l tank s mus t pas s two othe r test s whic hinvolve dropping th e fue l tank t o tes t impac t resistance . Th e firs t test , terme d th e dro p test , involve s dropping a full yloade d (equivalen t weigh t o f water ) tank fro m 3 0 fee t ont o an unyielding surface , s o tha t i t land s squarel y o n on e corner . Asecon d simila r tes t (terme d th e fillpip e test ) require s tha t a full yloade d tan k b e droppe d fro

m1 0 fee t ont o an unyielding surface , s o tha t i t land s squarel yo n it s fillpipe . I n neithe r case , mayth e tank no r an yfitting leak mor e tha n on e ounc e pe r minute . Base d o n conversation s wit hth e two HDG V manufacturers , th e vas t majorit yo f HDG V fue l tank s ar e frame mounte d (non-sid e mounted) . No sid e mounte d tank s ar e offere d a s standard equipment , an d onl yoccasionall yon e i s sol d a s a specia l order.[45,46 ] Thus , thi s analysi s will.focu s primaril y o n th e safet yventing an d leakag e tes t requirement s whic happl y t o frame mounte d tanks . However , th e dro p test s fo r sid e mounte d tank s wil l als o b e considered .P.8 3 -81

-

Figur e 2 6

Pictoria l Definitio n o f Side-Mounte d Fue l Tank . I f th e tank extend s t o th e lef t o f lin e Ao r t o th e righ t o f lin e B , the n th e tank i s side-mounted . / Line s Aand B ar e tangen t t o th e oute r side s o f ''th e fron t tires .P.8 4 -82

- 2 . Schoo l Bu s Requirement s I n additio n t o th e OMC S requirement s fo r frame-mounte d tanks , outline d above , schoo l buse s ar e require d t o mee t specifi c FMVS S 30 1 standards . However , thi s coverag e doe s no t include al l o f th e tes t requirement s a s prescribe d fo r passenge r car s an

d ligh t trucks . FMVS S 30 1 fo r schoo l buse s ove r 10,00 0 GVW

R require s a

n impac t wit ha contoure d movin g barrie r a t an

yspee d up t o an

d including 3 0 mph , a t an ypoin t an d angle . Depending o n th e design an d locatio n o f th e fue l tan k an d it s protectiv e structure , th e "wors t case " poin t an d angl e o f contac t i s determine d fo r eac hschoo l bu s model , an d th e contoure d moving barrie r impact s there . I n thi s test , th e fue l systemmus t b e designe d s o a s no t t o leak mor e than on e ounc e o f fue l pe r minute.[47 ] Thi s briefl ysummarize s th e curren t Federa l safet y standard s applicabl e t o fue l system s o n HDGV s . ove r 10,00 0 GVWR . I t i s importan t t o not e tha t mor e safet yrequirement s coul d b e applie d t o HDGV s ove r 10,00 0 GVW R i n the'future . Th e Departmen t o f Californi a HighwayPatro l recentl ysubmitte d a petitio n t o NHTS At o amen d FMVS S 30 1 t o includ e fue l system integrit ytesting fo r heavy-dut yvehicle s ove r 10,00 0 GVWR.[48 ] Wit hthi s background informatio n w e ar e no wprepare d t o discus s ho wth e difference s i n vehicle/fue l system configuration s an

d th e Federa l safet ystandard s ma yaffec t th e design o f an onboar d systemfo r an HDG V relativ e t o th e desig n fo r passenge r car s an d ligh t trucks . C . Distinction s i n HDG V Onboar d System s Jus t a s th e evaporativ e emissio n contro l system s use d o n HDGV s ar e verysimila r t o thos e use d o n passenge r car s an d light trucks , i t i s als o expecte d tha t an HDG V onboar d system woul d b e verysimila r i n design an d approac ht o tha t conceive d fo r lighter-weigh t vehicle s ( a possibl e HDG V onboar d systemi s show n i n Figur e 27) . However , some mino r variation s woul d exis t du e t o difference s i n HDG V fue l systemconfiguration s an d th e requirement s levie d b yth e applicabl e Federa l safet y standards . Befor e beginning a discussio n o f thes e mino r variations , i t i s valuabl e t o reiterat e a fewke ypoint s raise d previousl ywit hregar d t o th e magnitud e o f th e tas k o f implementing onboar d controls . First , lik e passenge r car s an d ligh t trucks , al l HDGV s no w incorporat e evaporativ e emissio n contro l system s (se e Figur e 25 ) an d thei r fue l system s mus t mee t th e presen t Federa l fue l syste mintegrit ystandard s (OMC S an d NHTSA) . Thus , a s befor e wit hth e lighte r weigh t vehicles , th e applicatio n o f onboar d system s i s bes t evaluate d incrementall yt o th e measure s alread y take n t o incorporat e evaporativ e emissio n control s an d mee t safet ystandards . Muc ho f th e ground wor k ha s alread ybee n completed , th e neede d modification s mad e an d component s added .Figur e 2 7 . POSSIBL E HDGV

INTEGRATE D EVAPORATIVE/REFUELINGSYSTE M

ir »

PRESSURE/VACUUM ^RELIE F MECHANICA LO RSOLENOI

D ACTUATE D VENT/ROLLOVE

R VALVE, LIMITIN GORIFIC E s & LIQUID/VAPO RSEPERATO R I o o I

SEALED- ^ GA S CA P MECHANICA

L SEA L 

### L

_ 5/8 " DI A -^13 ' LON

G T O PURG E INDUCTION POIN T
7. 5 LITER CANISTE R

3 0 GALLO

NHDG V FUELTAN

K

o oP.8 6
-84

- I n man ycase s n o change s t o presen t fue l systemsafet y assuranc e o r evaporativ e emissio n contro l measure s wil l b e needed . Second , i t i s importan t t o not e tha t HDG V onboard refueling an

d fue l tan

k evaporativ e emissio n contro l system s wil l likel yb e integrate d a s wit hlighte r weigh t vehicles . Thi s i s quit e eas yt o accomplis ho n HDGVs , sinc e theyno whav e separat e canister s an d contro l system s for fue l tan k an d fue l metering systemevaporativ e emissions . Thu s a whol e ne wsystem wil l no t b e adde d t o contro l HDG V refueling emissions ; instead th e refueling an

d fue l tan

k evaporativ e emissio n contro l system s wil l b e integrate d int o on e (compar e Figur e 2 5 wit h Figur e 27) . Thu s man yo f th e primarydesign consideration s whic happlie d fo r th e evaluatio n o f onboar d system s t o passenge r car s an

d ligh t truck s als o appl yt o HDGVs . Remembering th e expecte d similaritie s betwee n light an d heavy-dut yvehicl e onboar d systems an d tha t the factor s affecting th e implementatio n ar e als o th e same,.-the expecte d mino r variation s i n HDG V onboar d system s can no wb e discussed . Fo r sak e o f presentation , discussio n wil l begi n a t th e fillpip e an d followalong th e systemt o the canister . Th e analysi s wil l assume an integrate d onboar d refueling/fue l tank evaporativ e contro l system

a s discusse d above . T o begi n with , becaus e th e fillpipe s o n HDG V fue l tank s ar e eithe r relativel yshor t o r integra l wit hth e tank , ' liqui d fillnec k seal s whic hrequir e a n appreciabl e fil l heigh t ma yno t b e a practica l approac hi n some configurations . Du e t o thi s lac k o f fil l height , HDG V manufacturer s migh t elec t t o utiliz e a mechanica l sea l approac han d thu s woul d nee d t o incorporat e some typ e o f pressur e relie f devic e suc ha s wa s describe d previously . HDG

V fue l tanks , whic har e mad e o f stee l o r aluminum , no wus e a pressure-vacuu mrelie f valve , an d i t i s conceivabl e manufacturer s wil l simpl ymodif ytha t valv e fo r thi s application . However , unde r th e prope r backpressur e conditions , i t migh t b e possibl e t o us e a liqui d fillnec k sea l b yextending th e fillpip e horizontall yi n th e tank a s ha s bee n demonstrate d i n a prototyp e light-dut yprogram.[15 ] Asecon

d potentia l differenc e lie s i n th e diamete r o f th e refueling vapo r lin e an d relate d fue l tan k vent . Froma desig n perspective , th e tan k ven t an

d refueling vapo r lin e siz e (diameter ) coul d b e affecte d b yth e fue l dispensing rate . A s par t o f th e refueling emission s tes t procedure , EPAi s proposing tha t HDG V fue l system s b e designe d fo r refueling a t a maximu mrat e o f 1 0 gallon s pe r minute , th e same rat e a s prescribe d fo r othe r vehicles. * Thi s 1 0 gallo n pe r minut e Discussion s wit hgasolin e marketing interest s an d nozzl e manufacturer s indicat e tha t gasolin e availabl e t o passenge r cars , ligh t trucks , an d HDGV s (eithe r a t retai l o r privat e pumps ) i s normall yno t dispense d a t rate s greate r tha n 1 0 gpm .P.8 7 -85

- dispensing rat e result s i n a n increas e i n th e curren t orific e an d evaporativ e vapo r lin e diamete r fro mabou t 3/ 8 incht o abou t 5/ 8 inchfo r an HDG V onboar d system . However , t o minimiz e spillag e during refueling , th e OMC S ha s requirement s tha t an yliqui d fue l tan

k ove r 2 5 gallon s i n capacit ymus t b e abl e t o accep t fue l a t a rat e o f 2 0 gallon s pe r minute.[49 ] Fo r a n onboar d syste

m thi s requiremen t coul d lea d t o a increas e i n th e diamete r o f th e tank ven t outle t an d refueling vapo r line . I t shoul d b e noted , however , tha t whil e thi s requiremen t applie s t o al l heavy-dut yliqui d fue l tank s (bothdiese l an

d gasoline) , fundamentall yi t i s aime d mor e a t diese l fue l tanks . I t i s no t uncommo n t o encounte r an in-us e diese l fue l dispensing rat e o f 2 0 gp mo r mor e t o reduc e th e time neede d t o fil l a diese l tan k sinc e thes e tank s ar e typicall ymuc hlarge r than gasolin e tank s an d dua l diese l tank s ar e als o mor e common.[50 ] In-us e gasolin e dispensing rate s o n th e othe r han

d normall yd o no t excee d 1 0 gpm . .-Since in-us e gasolin e dispensing rate s usuall yd o no t excee d .1 0 gpm , an d EPA' s refueling certificatio n tes t woul d involv e a 1 0 gp m maximu mdispensing rate , OMCS' s requiremen t i n thi s are a may no t b e needed . EPAha s discusse d thi s matte r wit hDOT/OMCS , an d the yhav e expresse d a willingnes s t o conside r changing thi s requiremen t t o appl yonl yt o diese l fue l tanks.[51,52 ] I f thi s standard i s no t changed , an d a 1 0 gp

mdispensin g rat e limi t i s enacted , th e onl yeffec t woul d b e tha t th e refueling ven t orifice/lin e fo r thes e vehicle s woul d b e ove r sized . Nevertheless , becaus e HDG V fue l tank s d o no t us e lon g fillnecks , fue l dispensin g operation s woul d no t b e a s sensitiv e t o highe r backpressur e a s the ywoul d b e i n light-duty . Eve n i f th e refueling ven t orifice/lin e wer e size d fo r a 1 0 gallo n pe r minut e dispensing rate , fue l coul d b e dispense d a t a greate r rat e withou t prematur e shutoffs . Thu s i t ma yno t b e necessary t o siz e th e refueling orifice/ven t lin e t o matc hth e dispensing rat e requirements . However , i n optimizing system design s wit h regard t o fue l tank pressure , manufacturer s ma ychoos e t o us e a slightl ylarge r refueling ven t orific e tha n see n o n light-dut y applications . On e fina l manne r i n whic hHDG V onboar d system s migh t diffe r fro

mthos e o n lighte r weigh t vehicle s i s i n th e desig n o f th e rollove r protectio n device . Th e solenoi d activate d rollove r valv e (Figur e 19 ) o r th e combinatio n valv e (Figur e 21 ) coul d b e applie d t o HDG V fue l tank s i n thei r presen t configurations . On e manufacturer' s fue l tank desig n no w incorporate s a bal l typ e chec k valv e simila r i n principl e t o th e combinatio n valve.[41 ] Also , th e nozzl e actuate d valve s show n i n Figure s 9-1 5 coul d als o b e use d o n HDG V fue l tank s whic hhav e a fillpip e lengt ho f 6 inche s o r more . However , nozzl e actuate d valv e design s woul d hav e t o b e modifie d slightl yt o performo n fue l tank s whos e fillnec k i s essentiall y integra l wit hth e tank . Nonetheless , th e basi c approac han d operatio n woul d b e th e same .P.8 8 -86

- An yo f th e thre e rollove r valv e design s mentione d above coul d b e use d o n HDG V fue l tanks . Howeve r th e bes t choic e fo r an ytan k woul d depen

d o n th e fillpip e lengt hor othe r trade-off s relativ e t o cost , packaging etc . Wit hprope r design an d integratio n an

yo f thes e valv e design s coul d provid e rollove r protectio n in-use . Wit hthi s backgroun d o n HDG

V fue l systemconfigurations , safet yrequirements , an d HDG V onboar d system

characteristics , i t i s no wpossibl e t o addres s some o f th e uniqu e safet y concern s relate d t o HDG V onboard . Th e nex t segmen t o f thi s repor t discusse s an d addresse s potentia l impact s o f HDG V onboard o n fue l systemsafet yconsiderations . D . HDG

V Onboar d Safet yIssue s 1 . Introductio n Whil e non e o f th e comment s receive d regarding , th e safet y implication s o f onboar d control s specificall yaddresse d HDGVs , i t i s reasonabl e t o expec t tha t overal l concern s woul d b e simila r becaus e o f th e expecte d clos e resemblanc e betwee n ligh t an d heavy-dut yvehicl e onboar d systems . T o avoi d repeating muc ho f wha t ha s previousl ybee n discussed , thi s segmen t wil l primaril yfocu s o n uniqu e HDG V onboar d safet yconsiderations . Th e analysi s presente d i n Sectio n IV regarding maintenance , repair , tampering an d defect s an

d refueling operatio n safet y appl yequall yt o HDGV s an d wil l no t b e repeate d here . Th e potentia l problem s ar e simila r an d th e same basi c approac han d straightforwar d engineering solution s can b e used . Also , th e extensiv e analysi s i n Sectio n V regarding in-us e fue l system safet yals o applie s t o HDGVs . A s before , manufacturer s ar e expecte d t o manag e ris k appropriately ; ther e i s n o reaso n tha t adding an onboar d systemwoul d directionall yincreas e in-us e ris k ove r tha t no waccepte d wit hpresen t HDG V fuel/evaporativ e emissio n systems . However , a s wa s discusse d abov e th e fue l system configuration s an

d th e safet ytes t requirement s fo r HDG V fue l tank s ar e somewha t differen t fromlight-duty , s o some discussio n o f distinc t safet ytes t design requiremen t issue s i s appropriate . 2 . Safet yTes t Design Requirement s A s mentione d above , ther e ar e tw o separat e area s o f safet y tes t desig n consideration s fo r HDG V fue l systems . Th e Offic e o f Moto r Carrie r Safet y(OMCS ) ha s fue l systemsafet y regulation s whic happl yt o al l HDGVs , an d NHTS Aha s additiona l requirement s fo r schoo l buses . Thi s segmen t begin s wit ha summar yan d analysi s o f safet ydesig n consideration s relate d t o OMC S requirements . Following thi s i s a discussio n o f th e effect s o f NHTSA' s cras htes t requirements .P.8 9 -87

-

a . OMC S Requirements/Consideration s OMC S ha s establishe d fue l systemrequirement s for HDGV s t o insur e thei r structura l an d in-us e integrity . A s par t o f th e curren t requirements , HDG V fue l tank s mus t b e capabl e o f passing th e safet yventing system an d th e leakag e test s describe d previously . Currentl yHDG V fue l tank s employa bal l chec k valv e an

d pressur e vacuu

mrelie f valv e t o pas s thes e two tests . Sinc e th e refueling ven t orific e woul d b e somewha t large r wit ha

n onboar d system(5/8" ) th e bal l chec k valv e woul d hav e t o b e upgrade d t o provid e th e necessaryprotection . Littl e o r n o chang e t o th e pressur e vacuu mrelie f valv e woul d b e needed . Fo r a n HDG V onboar d system , th e protectio n no wsupplie d b y th e bal l chec k valv e coul d b e supplie d b yth e rollove r valv e design s describe d previously . Th e same thre e genera l type s o f rollove r protectio n device s tha t wer e discussed , fo r us e i n light-dut yapplication s (nozzl e actuated , solenoid , an d mechanicall yactivate d valves ) woul d al l b e feasibl e i n variou s heavy-dut yapplication s a s well . However , fo r tank s wit h littl e o r n o fillpip e (<6" ) th e nozzl e actuate d valv e desig n woul d probabl yhav e t o b e modifie d slightl yan d mounte d i n th e tan k instead o f o n th e fillneck . Asolenoi d o r mechanica l rollove r (ball ) valv e desig n coul d essentiall yb e use d a s show n earlier . HDG V an d light-dut yonboar d system s woul d b e functionall y identica l an

d woul d b e verysimila r i n desig n an d configuratio n excep t fo r caniste r siz e an d vapo r lin e length . O f course , t o mee t safet yrequirement s an d t o provid e i n us e protection , manufacturer s wil l hav e t o conside r th e structura l integrit y an d th e material s use d i n keysystemcomponent s jus t a s the yd o no wwit hothe r component s o f th e fuel/evaporative , system . Thus , some component s o f th e HDG V onboar d system(notabl yth e rollove r valve ) maynee d t o b e constructe d o f meta l t o provid e impac t resistanc e an d th e flammabilit yprotectio n demande d i n th e safet yventing test . Also , wit hregard t o impac t resistance , an yon e optiona l side-mounte d tank model , woul d b e subjec t t o two additiona l safet ytest s (drop tests ) designe d t o evaluat e th e tank' s impac t resistance . Aside-mounte d fue l tank woul d likel y utiliz e a rollove r valv e mounte d integra l t o or withi n th e tan k t o insur e it s integrit ydurin g th e dro p tests . Whil e thi s woul d no t b e difficul t t o desig n (man ycurren t fue l tank s contai n interio r components) , i t woul d represen t an additiona l design consideratio n fo r side-mounte d fue l tanks . Froma n in-us e safet yperspective , th e impac t resistanc e an d overal l integrit yo f rollove r valve s o n frame mounte d tank s woul d b e enhance d i f the ywer e mounte d integra l o r interna l t o th e tank . Thus , thi s approac hwoul d b e attractiv e fo r al l HDG V fue l tanks .P.9 0 -88

- I n conclusion , th e onl yHDG V onboard safet ydesign featur e introduced b

yth e nee d t o mee t OMC S safet yrequirement s i s th e upgrad e o f th e curren t rollove r protectio n device . Al l o f th e rollove r protectio n approache s discusse d fo r light-dut y application s (nozzl e actuated , solenoid , o r mechanicall y activated valves ) coul d b e use d t o mee t thi s requirement . Th e design , placement , an d constructio n o f th e rollove r valv e o n a particula r HDG

V fue l tan

k woul d depen

d i n par t o n fillpip e configuration , impac t resistanc e concerns , an d flammabilit y potential . b . NHTS ARequirements/Consideration s I n additio n t o OMC S requirements , al l schoo l buse s ove r 10,00 0 lbs . GVW

R mus t als o mee t specifi c requirement s o f NHTSA' s FMVS S 301 . A s describe d earlier , thi s involve s a singl e moving contoure d barrie r tes t a t a maximu mo f 3 0 mp han

d doe s no t includ e a rollove r test . I n thi s test, , th e barrie r impact s th e schoo l bu s a t th e mos t vulnerabl e locatio n o f th e fue l tank , an

d th e fue l syste

mmus t b e designe d s o a s no t t o lea k mor e than on e ounc e o f fue l pe r minute . A s wa s tru e o f OMC S requirements , a n acceptabl e schoo l bu s onboar d systemi s on e whic hdoe s no t impai r th e fue l tank' s abilit yt o mee t thi s requirement . A s i n th e light-dut ytest , th e crashworthines s o f al l th e onboard systemcomponent s (rollove r valve , charcoa l canister , critica l vapo r lin e an d vapo r lin e connection s betwee n th e to p o f the fue l tan

k an d th e rollove r valve ) woul d al l b e evaluate d i n the test . Desig n measure s simila r t o thos e describe d fo r passenge r car s an d ligh t truck s woul d hav e t o b e take n t o assur e th e integrit yo f thes e thre e keycomponents . Th e crashworthines s discussio n i n Sectio n IV- Aan d th e furthe r option s discusse d i n Sectio n V addresse d specifi c safet ydesign approache s fo r thes e component s whic hcoul d als o b e applie d t o schoo l buses , s o thi s wil l no t b e addresse d further . A s befor e wit hlight-dut yapplications , evaporativ e emissio n system s provid e directl yrelevan t technique s an d experienc e t o assis t i n prope r design , an d specifi c engineerin g measure s hav e bee n suggeste d t o dea l wit hpotentia l concerns . Furthermore , th e in-us e safet yo f onboar d refueling control s fo r HDGV s mus t b e considered . Th e locatio n o f onboar d syste mcomponents , a s wit hth e curren t fue l tan k an d evaporativ e emissio n controls , mus t minimiz e an ypotentia l safet yrisks . Muc ho f th e HDGV s fue l systemdamag e see n today i s cause d b

yforeign object s fro mth e road surfaces . Therefore , critica l onboard contro l systemcomponen t shoul d b e locate d o n th e HDG V i n a positio n whic hwil l minimiz e an y foreign objec t damage .P.9 1 -89

- I n conclusion , HDG V onboard system s d o no t introduc e an y ne wo r significan t problem s t o manufacturers ' attempt s t o design saf e fue l system s capabl e o f meeting NHTS Aan d OMC S safetyrequirements . Straightforward , viabl e engineering solution s ar e availabl e t o addres s al l problem s tha t hav e bee n identified . Therefore , onboard system s ar e expecte d t o b e integrate d int o HDG V fue l system s withou t reducing th e system' s abilit yt o mee t al l applicabl e Federa l safet yrequirements . 3 . Summary A s wa s mentione d i n th e light-dut ysectio n o f thi s report , EPA' s philosoph

yi n evaluating th e safet yimplication s o f requiring onboard control s (including thos e fo r HDGVs) , i s tha t n o increas e i n overal l ris k shoul d b e cause d o r accepted , beyon d tha t no wpresen t wit htoday' s fuel/evaporativ e system . Thi s applie s t o bot hcomplianc e wit hth e applicabl e Federa l Safet ystandard s an d th e in-us e safet yo f vehicle s equippe d wit honboar d systems . Thi s portio n o f th e analysi s ha s addresse d th e safet ytes t design requirements ' relate d t o implementing HDG

V onboar d systems , an d a s wa s th e cas e fo r light-dut yi t conclude s tha t straightforwar d engineerin g solution s ar e availabl e fo r al l o f th e potentia l safet y problem s whic hhav e bee n identified , an d saf e fue l system design s ar e achievabl e b yall . E . Cos t an

d Leadtime Consideration s EPAha s receive d n o comment s whic hdirectl yaddres s specifi c HDG

V onboar d safet ycos t an d leadtime implications . However , an analysi s o f th e cost s an d leadtime necessaryt o implemen t HDG

V onboar d control s safel yi s an integra l par t o f th e overal l evaluatio n o f th e feasibilit yo f thi s contro l approach . Th e firs t portio n o f thi s sectio n addresse s HDG V onboar d safet ycosts ; th e secon d discusse s HDG

V leadtime requirement s an

d describe s th e basi s fo r EPA' s leadtime estimates . Some o f th e cos t figure s cite d i n th e safet ycos t analysi s ar e draw

n fro ma broade r EPAanalysi s whic hdevelop s tota l HDG

V onboar d systemcost s i n 198 4 dollars.[17 ] 1 . Safet yCost s A s wa s tru e o f light-dut yonboar d safet ycosts , th e cost s neede d t o implemen t HDG V onboard control s fal l i n severa l areas . R& D typ e cost s wil l b e incurred , some ne wo r modifie d component s wil l b e neede d whic hma yslightl yaffec t vehicl e operating costs , an d safet ycertificatio n testing wil l b e necessary . However , befor e beginning a discussio n o f thes e costs , i t i s valuabl e t o discus s ho wEPA' s HDG V evaporativ e emissio n contro l requirement s impac t onboar d safet ycosts .P.9 2
-90

- A s wa s describe d i n th e light-dut ysectio n o f th e report , an onboard syste

m(even thos e fo r HDGVs ) i s i n man yway s an extrapolatio n o f curren t evaporativ e emissio n contro l technolog

yan d th e two system s ar e quit e similar . Sinc e onboard system s ar e basicall yextension s o f evaporativ e emissio n systems , clearl yman yo f th e safet ydesig n consideration s associate d wit honboard system s relate d t o meeting OMCS/NHTSArequirement s o r providing in-us e assuranc e hav e alread

ybee n addresse d i n evaporativ e emissio n system designs . Consequently , muc ho f th e groun d wor k require d t o insur e onboard safet yha s alread ybee n performed . I t i s importan t t o keep th e magnitud e o f th e HDG V onboar d safet y design proces s in perspective , becaus e muc ho f th e safet y technolog

yneede d i s simpl yan extensio n o f tha t whic halread y exists . Noting the "incremental " natur e o f onboar d safet yi n term s o f th e magnitud e o f th e tas k an d actua l cos t relative t o evaporativ e systems , i t i s no wpossibl e t o describ e th e component s whic hfacto r int o onboard safet ycosts.. . Basically , th e integratio n o f safet yint o a fue l system incorporating a

n onboard system

involve s four type s o f costs . Thes e four cost s ar e for : 1 ) design an d developmen t (R&D) , 2 ) specifi c hardware , 3 ) safet ytesting , an d 4 ) weigh t penalt y(or adde d fue l consumption) . Th e paragraph s tha t follo wdescrib e ho weac ho f th e cos t component s ar e affecte d byonboar d safety . T o begi n with , some researc han d developmen t wil l hav e t o b e performe d t o safel yintegrat e onboard control s int o HDG V fue l systems . EPAha s estimate d tha t th e tota l desig n an d developmen t cos t require d t o incorporat e onboar d system s i n HDG V fue l system s i s abou t $34,20 0 pe r famil yo r $1.5 0 pe r vehicl e (ove r 10,00 0 lb s GVWR) . Thi s cos t i s fo r an y developmen t effor t involve d i n combining th e component s o f an onboard systemwit hth e res t o f th e vehicl e t o for ma uni t tha t interact s safel yan d effectively . Becaus e safet yi s evaluate d inherentl yi n th e design an d developmen t proces s an d ye t i s onl yon e par t o f th e tota l effort , onl ya fractio n o f th e tota l cos t shoul d b e directl yallocate d t o safety . Th e light-dut y cos t sectio n explaine d wh ythi s fractio n i s likel yt o b e small . Th e same reasoning i s als o applicabl e fo r heavy-dut y applications , an

d therefor e i t wa s assume d tha t abou t 2 0 percen t o f R& D expenditure s relat e t o safety , whic htranslate s t o abou t $0.3 0 pe r vehicle . Th e secon

d componen t o f HDG V onboar d safet ycost s relate s t o specifi c hardwar e tha t mayb e require d t o insur e fue l system safety . EPAha s estimate d cost s fo r thre e specifi c items whic h hav e bee n identifie d a s potentia l component s to
- b e include d a s par t o f th e onboard systemdesign explicitl yfo r safet y reasons . Thes e thre e items ar e 1 ) a rollove r valve , 2 ) a pressur e relie f mechanism , an d 3 ) fue l system

modification s necessaryt o safel yincorporat e a rollove r valve , pressur e relie f mechanism , or othe r onboar d hardware . HDG V rollove rP.9 3 -91

- valve s shoul d no t diffe r i n cos t fro mlight-dut yvalve s sinc e theywoul d essentiall yb e th e same . Therefore , th e light-dut y estimat e o f $3.0 0 t o $6.0 0 wil l als o b e use d here . Th e secon

d safet yhardwar e cos t i s fo r a pressur e relie f mechanism . Sinc e thi s mechanis mwoul d b e neede d fo r onboar d systems incorporating a mechanica l fillnec k seal , man yHDGV s woul d requir e it s use . EPA' s analysi s price s thi s devic e a t $2.50.[13 ] A t thi s point , thi s estimat e i s considere d t o b e veryconservative , sinc e th e possibilit yexit s tha t th e presen t pressur e relie f devic e can b e modifie d t o performthi s function . Th e fina l onboar d safet yhardwar e cos t account s fo r an y fue l system

modification s tha t woul d b e necessaryi n orde r t o safel yaccommodat e an yonboard contro l hardware . Fo r example , a HDG V fue l tan

k o r fillpip e migh t hav e t o b e re-shape d o r modifie d i n orde r t o accep t a rollove r valve . Also , some sligh t re-routing o f th e fue l system' s vapo r .line s mayb e required . EPAha s estimate d a tota l modificatio n cos t t o b e $0.5 0 pe r fue l tank . Onl ypar t o f thi s tota l cos t woul d b e require d for safet ypurposes . However , becaus e safet y inherentl yenter s int o th e decisio n t o mak e an ymodifications , i t i s difficul t t o acces s wha t par t o f th e tota l modificatio n cos t shoul d b e allocate d t o safety ; perhap s hal f ($0.2 5 pe r fue l tank ) coul d b e considere d a s drive n bysafet yrelate d concerns . Summing up th e thre e individua l safet yhardwar e cost s pe r fue l tan

k yield s a tota l estimate d figur e i n th e rang e o f $5.7 5 t o $8.75 . However , thi s cos t estimat e doe s no t includ e manufacture r overhea d an d profit . Consequently , i n orde r t o obtai n th e retai l pric e equivalen t cost , thes e estimate s mus t b e multiplie d b

ya markup factor . Presently , a markup facto r valu e o f 1.2 7 appear s representative.[37 ] Therefore , afte r integratio n o f th e marku p factor , a tota l retai l pric e equivalen t HDG

V safety-relate d hardwar e cos t pe r fue l tan k fall s withi n th e rang e o f $7.3 0 t o $11.10 . Sinc e 1 5 percen t o f HDGV s hav e dua l tanks , th e tota l HDG V safety-relate d hardwar e cos t rang e i s $8.4 0 t o $12.8 0 Th e thir d componen t o f safet ycost s i s fo r an ysafet y testing tha t woul d b e necessary . Unlik e light-dut ytes t costs , EPAha s no t thoroughl yinvestigate d HDG V safet ytes t costs . However , safet ytes t cost s wer e estimate d i n an attemp t t o determin e th e approximat e magnitud e o f th e pe r vehicl e HDG V safet ytes t cost . Tabl e 6 show s tha t eve n whe n fairl ylibera l safet ytes t cost s ar e assumed , th e resulting cost/vehicl e o f $0.7 0 i s veryminima l i n th e lon g term . Th e fourt hcomponen t o f safet ycost s i s th e estimat e o f th e adde d fue l consume d ove r th e lif e o f th e vehicl e du e t o th e increas e i n vehicl e weigh t resulting fro madde d safet y hardware . Th e amoun t o f weigh t adde d t o vehicl e fromaP.9 4
-92

- Tabl e 6 HDG V Fue l Tank Safet yTes t Cost s Estimat e 1 . OMC S Requirements : 2 test s pe r HDG

V fue l systemconfiguratio n (SafetyVen t Tes t an d Leakag e Test ) Conservativ e Cost/Tes t Estimate : $2,00 0 8 HDG V Fue l Tan

k Configuration s Tota l OMC S Safet yTes t Cost : $32,00 0 2 . NHTS ARequirements : 1 tes t pe r HDG

V fue l systemconfiguratio n (3 0 mp hmoving barrier ) Conservativ e Cost/Tes t Estimate : $30,00 0 7 Schoo l Bu s Configuration s ( 7 manufacturers , 1 config./manufacturer ) Tota l NHTS ASafet yTes t Cost : $210,00 0 3 . Tota l HDG

V Fue l Tank Safet yTes t Cost : $242,00 0 4 . Cost/Vehicl e (Amortize d a t 1 0 percen t ove r 5 year s o f vehicl e sales*) : $0.7 0

* Assume d tha t al l bu s manufacturer s wil l cras htes t thei r vehicles . * * Vehicl e sale s wer e estimate d a t 90,000/year .P.9 5 -93

- rollove r valv e or pressur e relie f mechanis mi s ver ysmal l (0. 4 lbs) , an

d becaus e HDGV s ar e les s sensitiv e t o weigh t change s than lighte r weigh t vehicles , o n averag e les s tha n $0.3 0 i n added fue l cost s wil l resul t fro mthei r inclusio n int o th e HDG V onboard system.[24 ] Atota l onboard safet ycos t i s calculate d b ysumming al l fou r individua l componen t costs . Tota l safety-relate d onboar d cost s pe r famil yaverag e abou t $270,000 , an d th e pe r vehicl e cost s rang e fro

m$9.7 0 t o $14.1 0 o r abou t 20-2 5 percen t o f th e tota l cos t depending o n th e typ e o f rollove r valv e used . 2 . Leadtime I f EPAwer e t o implemen t an HDG V onboar d requirement , i t woul d b e necessaryt o allowmanufacturer s enoughleadtime t o adequatel yprepar e for th e requirement . Th e HDG V preparatio n proces s woul d involve th e same individua l task s tha t woul d ente r int o th e light-dut yprocess : systemdesign , .development , testing , tooling , certification , an d safet yevaluation . Althoughtwo o f thes e leadtime task s (certificatio n an d safet y evaluation ) woul d involve somewha t differen t procedure s fo r HDGVs , theywil l essentiall yrequir e th e same amoun t o f tim e an d woul d facto r int o th e tota l proces s i n th e sam e manne r a s i n light-duty . Therefore , i t i s estimate d tha t 2 4 month s woul d b e th e tota l amoun t o f leadtime require d b yHDG V manufacturers , an d Figur e 2 5 whic hshow s th e parallel/sequentia l progressio n o f th e individua l leadtime component s woul d b e essentiall yth e same fo r HDGVs . O f th e variou s leadtime component s show n i n Figur e 25 , al l bu t two woul d b e essentiall yth e same fo r HDGV s a s the ywoul d fo r light-dut yapplications . Thes e two ar e certificatio n an d safet yevaluation . I n bot hcases , th e HDG V processe s appea r a s thoughthe ywoul d tak e les s time t o complet e tha n thei r light-dut ycounterpart s becaus e thes e task s woul d b e likel yt o b e les s difficul t t o perform . Fo r example , i n som e cases , durabilit yassessment s fo r certificatio n o f HDGV s doe s no t requir e an

yactua l vehicl e testing ; benc hevaluation s ca n b e substitute d base d o n th e manufacturer s engineering judgment . Thi s coul d sav e considerabl e time . A s far a s safet yevaluatio n goes , HDG V fue l tank test s performe d t o mee t OMC S requirement s woul d b e muc hsimple r t o perfor mthan NHTSA' s safet ycras htest s fo r passenge r car s an d ligh t trucks . Also , whe n NHTS Arequirement s d o appl y(a s i n th e cas e o f schoo l buses ) the yonl yinvolv e a singl e cras htes t wit hn o rollover . (Thi s i s mino r i n comparison•t o test s which , involve multipl e crashe s wit hrollover. ) Therefore , th e amoun t o f time allowe d for light-dut ycertificatio n (10-1 2 months ) an d safet yevaluatio n (>1 2 months ) shoul d als o b e sufficien t fo r HDGV s sinc e th e heavy-dut yprocesse s ar e les s involved . Overall , 2 4 month s o f leadtime fo r HDG V onboar d i s quit eP.9 6 -94

- reasonable . Thi s i s especiall ytru e whe n on e consider s th e developmen t wor k alread ycomplete d an

d th e "incremental " natur e o f onboard i n relatio n t o curren t evaporativ e emissio n systems . EPA' s 24-mont hleadtime estimat e i s supporte d b ypas t experienc e wit hpreviou s HDG V evaporativ e emissio n rulemakings . Thes e rulemaking s includ e th e Californi a Ai r Resource s Board origina l 197 8 6. 0 g/tes t HDG V evaporativ e emissio n standard whic hwa s implemente d wit hjus t 2 1 month s o f leadtime.[53 ] Th e stringencyo f thi s standar d wa s increase d fo r 198 0 mode l yea r HDGV s allowing onl y2 g/test . [54 ] Whil e thi s stricte r standard wa s promulgate d wit h3 7 month s o f leadtime , manufacturer s had t o mee t th e 197 8 standar d first , whic heffectivel ylimite d th e leadtime fo r th e 198 0 standar d t o abou t 2 4 months . On e fina l evaporativ e emissio n standar d whic h wa s implemente d wit h24 < "month s o f leadtime wa s EPA' s 198 5 HDG V standard . I n eac ho f thes e thre e rulemakings , manufacturer s faced leadtime factor s identica l t o th e ones , tha t woul d accompan

yan onboard requirement , including safety . Sinc e manufacturer s wer e abl e t o safel yan d effectivel yintegrat e evaporativ e emissio n control s int o thei r vehicle' s fue l system s wit h2 4 month s o f leadtime , an d sinc e th e magnitud e o f th e onboard implementatio n tas k i s similar , manufacturer s shoul d als o b e abl e t o safel yan d effectivel yintegrat e onboar d int o vehicl e fue l system s wit h2 4 month s leadtime . A s far a s safet ydevelopmen t an d evaluatio n i s concerned , EPA' s HDG

V leadtime estimat e i s als o supporte d b yth e pas t experienc e o f OMC S an d NHTS Ai n implementing variou s HDG V fue l syste mrequirements . I n 1973 , OMC S extende d it s safet ytes t requirement s t o includ e previousl yunaffecte d non-side-mounte d (frame-mounted ) HDG V fue l tanks . Thi s requiremen t wa s implemente d wit hjus t 1 8 month s o f leadtime . [55 ] Als o i n 1977 , FMVS S 30 1 wa s extende d t o includ e schoo l buses , an d thi s requiremen t wa s implemente d wit h1 7 month s o f leadtime.[56 ] Thi s experienc e indicate s tha t 2 4 month s o f leadtime allow s manufacturer s sufficien t time t o facto r i n safety . Base d o n th e informatio n provide d above , i t appear s tha t 2 4 month s i s adequat e time t o implemen t HDG V onboar d controls , wit hful l consideratio n o f al l safet yconcerns . Becaus e safet y evaluatio n ca n procee d i n paralle l t o thre e othe r tasks , mor e than a yea r i s availabl e fo r actua l fue l tank safet ytests , schoo l bu s cras htesting , o r an ydesire d compute r simulation . Thi s allow s adequat e leadtime t o properl yintegrat e safet yint o HDG V onboard system s especiall ysinc e manufacturer s ca n utiliz e an d expan

d safet ytechnolog yuse d i n curren t evaporativ e emissio n contro l system s t o develop effectiv e onboar d systems . Also , muc ho f th e safet ydevelopmen t whic hwoul d b e require d ha s alread

ytake n plac e wit hth e identificatio n an d resolutio n o f suc hpotentia l safet yissue s a s rollove r protectio n an d fue l tank pressur e relief . Consequently , a 24-mont hleadtime perio d woul d provid e manufacturer s wit hsufficien t opportunit yt o develop saf e an

d effectiv e onboard systems .P.9 7 -95

- Whil e th e curren t leadtime estimat e o f 2 4 month s i s reasonabl e fo r al l vehicl e model s including HDGVs , EPAi s sensitiv e t o manufacturer s concern s regarding leadtime requirements . EPAi s committe d t o providing manufacturer s th e leadtime necessaryt o implemen t onboard control s safel yan d effectively . Designin g saf e onboard control s fo r some uniqu e HDGV s mayrequir e mor e leadtime . Suc hHDGV s includ e thos e wit h atypica l dut ycycles , uniqu e fue l tan k o r bod

yconfigurations , an d thos e HDGV s fro msecondarymanufacturers . Consequently , EPAwoul d includ e HDGV s a s par t o f an yoveral l consideratio n o f additiona l leadtime o r a shor t phase-i n perio d for onboard controls . F . Summary/Conclusio n Th e purpos e o f thi s sectio n wa s t o identif yan d addres s th e potentia l effect s onboar d control s coul d hav e o n a HDG V manufacturer' s fue l systemsafet ydesigns . Afte r analyzing th e potentia l safet yconcern s relate d t o implementing HDG V onboar d systems , EPAha s foun d tha t lik e passenge r car' s an d ligh t trucks , heavy-dut yonboar d system s ar e extension s o f curren t evaporativ e system s an d corresponding safet yconsideration s ar e simila r i n natur e t o thos e discusse d fo r light-dut y applications . Whil e a fewuniqu e consideration s d o exis t (i n par t becaus e o f difference s i n testing requirements , tank designs/locations , structura l integrity , siz e etc.) , n o increas e i n overal l ris k shoul d b e cause d o r accepted , beyond tha t no wpresen t wit htoday' s HDG V fuel/evaporativ e system . Thi s applie s t o bot hcomplianc e wit hth e applicabl e Federa l safet ystandard s an d th e in-us e safet yo f HDGV s equippe d wit h onboar d systems . A s wa s th e cas e fo r light-duty , straightforwar d engineerin g solution s ar e availabl e fo r al l o f th e potentia l safet yproblem s whic hhav e bee n identified , an d tha t whil e fina l choice s regarding exac t systemdesign s li e wit hth e manufacturers , saf e fue l systemdesign s ar e achievabl e b yall . EPAestimate s tha t HDG V safet ycost s contribut e abou t 20-2 5 percen t o f th e tota l HDG V onboar d systemcos t an d shoul d fal l withi n th e rang e o f $9.7 0 t o $14.10 . Wit hregard t o leadtime , thi s analysi s indicate s tha t 2 4 month s appear s t o provid e HDG

V manufacturer s wit hadequat e tim e t o prepar e fo r th e saf e an

d effectiv e implementatio n o f onboar d controls , bu t a s befor e wit hpassenge r car s an d ligh t truck s th e possibilit y o f th e nee d fo r mor e leadtime fo r some vehicl e model s mayexist . VIII . Conclusio n EPAha s investigate d an d analyze d eac ho f th e potentia l onboar d system

safet yissue s raise d b yth e commenters . Afte r carefull yconsidering al l o f th e potentia l impact s a n onboar d systemcoul d hav e o n th e overal l safet yo f a vehicle' s fue l system , i t i s conclude d tha t straightforward , reliable , relativel yinexpensiv e engineering solution s exis t fo r eac ho fP.9 8 -96

- th e potentia l problem s identified . Furthermore , n o increas e i n ris k nee d occur o r b e accepte d becaus e o f th e presenc e o f an onboard system . Onboar d equippe d vehicle s can b e designe d t o pas s FMVS S 30 1 an d provid e a leve l o f in-us e fue l system integrityequa l t o or bette r than . tha t achieve d o n presen t vehicle s whic hincorporat e evaporativ e emissio n contro l systems . O f cours e fina l choice s regarding exac t onboar d syste mdesign s li e wit hth e manufacturers , an d eac h manufacture r wil l choos e th e approach/systemwhic hprovide s th e bes t balanc e o f cost , safety , an d othe r keyfactors . EP Awoul d no t adop t a

n onboard requiremen t unles s i t wa s clea r tha t saf e fue l systemdesign s wer e available . Thi s repor t demonstrate s thi s t o b e th e case . Saf e fue l systemdesign s ar e achievabl e b yal l manufacturers . Furthermore , i t i t i s quit e possibl e tha t overal l fue l syste mimprovement s coul d accompan yth e implementatio n o f onboard control s an d lea d t o a ne t improvemen t in.th e leve l o f fue l syste

msafet yo n in-us e vehicles . Fo r example , collapsibl e bladde r tank s ar e on e design optio n tha t coul d contro l refueling emissions , reduc e evaporativ e emission s an d a t th e same time improve fue l systemsafety . Manufacturer s can an d ar e expecte d t o desig n an d implemen t onboard system s i n a manne r whic hprovide s a t leas t th e same leve l o f fue l systemsafet ya s achieve d o n presen t vehicles . I n addition , a numbe r o f design option s an d othe r measure s ar e availabl e wit honboar d systems , whic hsugges t tha t fue l system safet yin-us e can b e improve d along wit hth e incorporatio n o f onboard contro l systems .P.9 9 -97

- IX . Reference s 1 . Letter , Thoma s Hanna , MVM Aan d Georg e Nield , AI At o Le e Thomas , U S EPA , Decembe r 22 , 1986 . 2 . Letter , Bria n O'Neill , IIH S t o Le e Thomas , U S EPA , Septembe r 23 , 1986 . 3 . Letter , RalphHitchcock , NHTS At o Charle s L . Gray , Jr. , U S EPA , Novembe r 13 , 1986 . 4 . America n Petroleu mInstitut e Comment s o n U S EPA Gasolin e Marketing Study , Novembe r 8 , 1984 , Docke t A-84-07 . 5 . Letter , Clarenc e Ditlow , Cente r fo r Aut o Safet yt o Le e Thomas , U S EPA , Marc h20 , 1987 . 6 . "Surveyo f Evaporativ e Emissio n Systems . Conditio n o f In-Use , HighMileag e Automobiles" , AP I Publicatio n 4393 , February , 1985 . 7 . Bor g Warne r Contro l System s Catalog , February1986 . 8 . "Stud

yo f Gasolin e Volatilit yan d Hydrocarbo n Emission s fro

mMoto r Vehicles" , U S EPA , AA-SDSB-85-5 , Novembe r 1985 . 9 . "Summaryan d Analysi s o f Comment s o n th e Recommende d Practic e fo r th e Measuremen t o f Refuelin g Emission" , U S EPA AA-SDSB-87 , Marc h1987 . 10 . Letter , T.M . Fisher , Genera l Motor s t o Jame s B . Weigold , U S EPA , Novembe r 8 , 1984 , Docke t A-84-07 . 11 . For d Moto r Compan yComment s o n Evaluatio n o f Ai r Pollutio n RegulatoryStrategie s fo r th e Gasolin e Marketin g Industry , Novembe r 8 , 1984 , Docke t A-84-07 . 12 . Chrysle r Corporatio n Comment s o n Evaluatio n o f Ai r Pollutio n RegulatoryStrategie s fo r th e Gasolin e Marketin g Industry , Novembe r 5 , 1984 , Docke t A-84-07 . 13 . "Toyot a Informatio n o n Refuelin g Vapo r Recovery" , Presentatio n t o U S EPA , Marc h19 , 1986 . 14 . "Onboard Contro l o f Vehicl e Refuelin g Emission s Demonstratio n o f Feasibility" , AP I Publicatio n 4306 , Octobe r 1978 . 15 . "Vehicl e Onboar d Refueling Control" , AP I Publicatio n 4424 , Marc h1986 .P. 1 -98

- 16 . "Evaluatio n o f th e Feasibilit yo f Liqui d Fillnec k Seals, " U S EPAAA-SDSB-86-003 , Decembe r 1986 . 17 . Evaluatio n o f Air ' Pollutio n RegulatoryStrategie s fo r Gasolin e Marketing Industr y- Respons e t o Publi c Comments , Marc h1987 . 18 . "Onboard Refueling Vapo r RecoveryCos t Study, " Muelle r Associate s Inc. , Decembe r 1986 . 19 . "Refueling Emission s fro mUncontrolle d Vehicles, " EPA-AA-SDSB-85-6 , Dal e Rothma n an d Rober t Johnson , 1985 . 20 . "Expansio n o f Investigatio n o f Passenge r Ca r Refueling Losses, " EPA-460/3-76-006 , U.S . EPA , OAWM , OMSAPC , ECTD , Septembe r 1975 . 21 . "Evaluatio n o f Federa l Moto r Vehicl e Safet yStandar d 301-75 , Fue l SystemIntegrity : Passenge r Cars, " DOT . HS-806-335 , January1983 . 22 . Fata l Acciden t Reporting System , NHTSA , DOT , 1980-1984 . 23 . Moto r Vehicl e Safet yStandar d No . 301-75 , Fue l SystemIntegrity : 3 9 F R 10588 , Marc h21 , 1974, . PART 571 ; S 301-75-5.1 , 5.2 , 5.3 , an d 4 0 FR 48352 , Octobe r 15 , 1975 , PAR T 571 : S 301-75-5.1 , 5.2 , 5.3 , 5.4 . 24 . Letter , Davi d E . Martin , G Mt o BarryFelrice , NHTSA , Marc h24 , 1986 . 25 . Letter , Hiroyuk i Shinbura , Nissa n Researc han d Developmen t t o Charle s Gray , U.S . EPA , Apri l 14 , 198 7 26 . Not e fro

mBo bWilliams , NHTSA , t o Glenn Passavant , U S EPAincluding 3 compute r fil e printouts , Novembe r 13 , 1986 . 27 . "Design o f a Fir e Proo f Vehicle, " Chan , C.Y.K./Chi , L.L. , Californi a University , Berkeley , Fir e Researc hGroup. , Repor t No . UCB-FRG-75-18 , July , 1975 . 28 . " APerspectiv e o n Automobil e Cras hFires" , SAE 850092 , C . Warner , M . James , R . Wooley . 29 . "Supplemen t t o Genera l Motor s Commentaryt o th e Environmenta l Protectio n Agenc yRelativ e t o Onboar d Contro l o f Vehicl e Refueling Emissions, " Jun e 1978 . '30 . NHTS APres s Release , Jun e 11 , 198 7 an d NHTS AFac t Shee t o n Th e Ne wCa r Assessmen t Progra man d a Summaryo f th e Ne wCa r Assessmen t Progra mTes t Results , Augus t 5 , 1986 .P. 2

31 . Sensors ; Marc h1 , 32 . Johnson , 2310-75

-

f i • * -99

- Ann Arbo r News , "'Smart ' Suspensio n SystemInclude s Computers, " Ann Arbo r News , Newhous e New s Service , 1987 . "Spille d Fue l Ignitio n Source s an d Countermeasures, " N. , DO T Contrac t No . HS-4-00872 , Repor t No . 118 , September , 1975 . 'Tncf e r\f

rinK n a rrl \Tzmnr- Dannirori ? HarHuarfl " .Tan t Faucet t an

d Muelle r Associates , February1985 . 34 . "Repor t o n Qualit yChange s fo r 197 7 Mode l Passenge r Cars " USDL-76-1376 , BL S Novembe r 1976 . 35 . "Repor t o n Qualit yChange s fo r 197 6 Mode l Passenge r Cars, " USDL-75-626 , BL S Novembe r 1975 . 36 . "Cos t Estimation s fo r Emissio n Contro l Relate d Components/System s an d Cos t MethodologyDescription, " EPA-460/3-78-002 , Marc h1978 . 37 . "Updat e o f EPA' s Moto r Vehicl e Emissio n Contro l Equipmen t Retai l Pric e Equivalen t Calculatio n Formula, " Jac k Faucet t Associate s fo r U.S . EPA , Septembe r 4 , 1985 . 38 . "Cos t o f Cras hTesting t o Assur e Fue l System Integrit yfo r Onboar d Systems, " EPAMemorandum , Rober t Johnso n t o the Record , U.S . EPA , OAR , OMS , ECTD , SDSB , Septembe r 2 , 1986 . 39 . "Tra

p Oxidize r Feasibilit yStudy" , U.S . EPA , OANR , OMSAPC , ECTD , SDSB , Marc h1982 . 40 . "Characterizatio n o f Fuel/Vapo r Handlin g System s o f Heavy-Dut yGasolin e Vehicle s ove r 10,00 0 Pound GVW" , Jack . Faucet t Associates , Septembe r 1985 . 41 . "Evaluatio n o f Ai r Pollutio n RegulatoryStrategie s fo r th e Gasolin e Marketing Industry" , U S EPA , OAR , EPA-450/3-84-012a , Jul y1984 . 42 . Memorandu

mt o File , Revie wo f Genera l Motor s Heav y Dut yEngine/Value d Certificatio n Procedures , Tea mI V Certificatio n Branch , Augus t 4 , 1986 . 43 . Memorandu

mt o File , Revie wo f For d HD E Certificatio n Procedures , Tea

m I V Certificatio n Branch , Augus t 5 , 1986 . ,44 . 4 9 CF R Par t 393.6 5 t o 393.67 . 45 . Conversatio n wit hJi mFeiten , GM , Marc h16 , 1987 . 46 . Conversatio n wit hBo bBisaro , Ford , Marc h16 , 1987 .P. 3 -100

- 47 . Moto r Vehicl e Safet yStandar d NO . 301-75 , Fue l SystemIntegrity : 4 0 FR 48352 , Octobe r 15 , 1975 , PART 571 : S 301-75-5. 4 an

d 4 1 FR 36026 , Augus t 26 , 1976 , PART 571 : S 301-75-5. 4 48 . Letter , L.M . Short , Departmen t o f Californi a Highway Patro l t o Dian e Steed , Nationa l HighwayTraffi c Safet y Administration , May30 , 1986 . 49 . 4 9 CFR 393.6 7 (c)(7)(ii) . 50 . Base d o n a A P o f 1 0 ps i for Emc o Wheato n Mode l A600 0 an

d OP WMode l 7 H diese l fue l nozzles . 51 . Letter , Charle s L . Gray , Jr. , U S EPA , t o Offic e o f Moto r Carrie r Safety , May27 , 1987 . 52 . Conversatio n wit hJi mBrittell , DOT/OMCS , February 18 , 1987 . 53 . Publi c Hearing t o Conside r Amendment s t o Californi a Fue l Evaporativ e Emissio n Tes t Procedure s for 197 8 an d Subsequen t Mode l Gasoline-Powere d Vehicles , Resolutio n No . 76-15 , Marc h31 , 1976 . 54 . Publi c Hearing o n Propose d Change s t o Regulation s Regarding Vehicl e Evaporativ e Emissio n Standard s fo r 198 0 an d Subsequen t Mode l Moto r Vehicles , Resolutio n No . 76-45 , Novembe r 23 , 1976 . 55 . OMC S Regulations , Par t 393-Part s an d Accessorie s Necessaryfo r Saf e Operation s (Fue l Systems) : 3 6 FR 15444 , Augus t 14 , 1971 , an d 3 7 FR 4340 , Marc h2 , 1972 . 56 . FMVS S 301 , 4 0 F R 48352 , Octobe r 15 , 1975 .