P. 1



# OAR Box 1818 Prepped byOllie Stewart



### Document

Number: 

# 5 ) ll-C- 2 Docket Number: 

# A-87-1 1

Printed 11/6/20083:12:41 PM

Sheet 5of 79P. 2

• m 

## P) pAC T EPA-AA-SDSB-87-0 5 ^""B7-I C

Technica l Repor t

''/() W Safet yImplication s o f Onboar d Refuelin g

Vapo r Recover ySystem s

Marc h198 7

DRAF T D O NO T QUOT E O R CIT E

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 and 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 regulator yaction .

Standard s Developmen t and 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 and Radiatio n U . S . Environmenta l Protectio n Agenc yP. 3 

### Tabl eo f

Content s Sectio nPag e

I . Executiv e Summary3
II . Introductio n 7
III . Onboar d Contro l SystemDescriptio n 9
IV . Design Consideration s fo r a Saf e Onboar d System2 6 V . In-Us e Fue l SystemSafet y4 8 VI . Cos t an

d Leadtime Consideration s 6 0 VII . Heavy-Dut yGasolin e Vehicl e Requirement s 7 3 VIII . Conclusio n 9 5
IX . Reference s 9 6P. 4


### -3

- I . Executiv e Summar y Th e purpos e o f thi s technica l repor t i s t o evaluat e the safet yimplication s o f requirin g onboard refuelin g vapo r recover ysystem s o n gasoline-powere d passenge r cars , ligh t truck s an

d heavy-dut yvehicles . In tha t light , specia l attentio n i s give n t o the analysi s o f the design consideration s for a saf e onboard systeman d the othe r measure s necessaryt o insur e tha t the design consideration s incorporate d ar e capabl e o f providing a hig

hleve l o f in-us e fue l systemintegrity . Onboar d refueling system s ar e in man yway s simila r t o presen t fue l tank evaporativ e emissio n systems . Th e emission s emanat e fro

mthe sam

e location o n the vehicl e an d th e basi c technolog

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

yo f the component s ar e analagous , i f no t essentiall yidentical , an d the configuration/layou t o f the system s o n the vehicl e i s als o expecte d t o be abou t the same . In fact , thes e tw

o 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 tan

k evaporativ e emissio n system s int o on e integrate d systemwhic hcan serve bot hpurposes . Th e fac t tha t thes e system s ar e simila r an d wil l be integrate d ha s two effect s o n the safet yo f onboard systems . First , man yo f the approache s an

d technique s used t o safel yimplemen t evaporativ e emissio n contro l system s can als o be applie d t o insur e the saf e implementatio n o f a n integrate d onboard refueling/evaporativ e emissio n system . Second , an ysafet yproblem s relate d t o integrate d onboard/evaporativ e system s shoul d be evaluate d incrementa l t o presen t evaporativ e systems . Quit e simply , ther e i s no nee d t o ad d a whol e newsystem t o the vehicle . Concern s ove r the potentia l safet yimplication s o f onboar d system s have , however , bee n raised . Thes e concern s can be groupe d int o four genera l areas . Thes e includ e requirement s t o pas s the Nationa l HighwayTraffi c Safet yAdministratio n (NHTSA ) safet ytests , the effect s o f tampering an d systemdefects , refueling operations , an d in-us e fue l systemsafety . Concern s wit hth e design requirement s necessaryt o compl y wit hthe NHTS Asafet ytest s focuse d o n the need t o integrat e a n onboar d systemint o a vehicl e i n a manne r whic hwoul d provid e the crashworthines s an d rollove r protectio n demande d b yFedera l Moto r Vehicl e Safet yStandard (FMVSS ) 301 . EPA' s analysi s indicate s tha t crashworthines s fo r the ke yvapo r line s an d othe r systemcomponent s coul d be accomplishe d usin g man yo f the sam e approache s an

d technique s nowapplie d successfull yt o evaporativ e emissio n systems . Further , the rollove r protectio n nowprovide d fo r the fue l tan k throughth e us e o f a limiting orific e ca n be gaine d throughthe applicatio n o f on e o f the severa l rollove r valv e design s nowavailable .P. 5

-4

- Concern s hav e als o bee n expresse d tha t caniste r tamperin g an d componen t defect s coul d lea d t o in-us e safet yproblems . Whil e caniste r tamperin g i s infrequent , th e rat e ca n b e reduce d an d th e potentia l safet yeffect s eliminate d throug hprope r placement . Manufacturer s ar e expecte d t o conside r th e safet y implication s o f tamperin g whe n evaluatin g caniste r locatio n option s o n th e vehicl e a s the yd 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 syste mcomponent 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 suc hoccurrence 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 yimplementin g evaporativ e controls , i t i s likel ytha t an integrate d onboard/evaporativ e syste mcoul d b e implemente d wit hn o mor e (and perhap s less ) problem s tha n presen t evaporativ e emission s systems . Concern s ove r th e safet yo f refuelin g 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 , and tha t i f a mechanica l sea l i s use d a simpl e pressur e relie f devic e ca n b e use d t o eliminat e any overpressur e concerns . A s discusse d i n th e analysis , a fe w othe r les s significan t potentia l problem s hav e ver y straightforwar d engineerin g solutions . Finally , whil e i t i s clea r tha t onboard-equippe d vehicle s ca n 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 syste mintegrit yin-us e ma ydecreas e b

ysom e nori-quantifiabl e amoun t becaus e FMVS S 30 1 can' t cove r al l potentia l acciden t situation s and a n onboar d syste m require s modification s and 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 yfollo wtha t syste mmodification s o r addition s wil l caus e a n increas e i n ris k ove r presen t systems . Bot hvehicl e and fue l syste msafet yar e evaluate d a s a n integra l par t o f th e overal l desig n and developmen t process . Thi s involve s multipl e trade-offs , balances , and compromise s wit hothe r ke ydesig n considerations . Give n th e nee d t o conside r al l ke ydesig n criteria , manufacturer s accep t o r 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 manycase s th e leve l o f safet yachieve d in-us e goe s beyon d tha t require d b

yFedera l standards , bein g drive n b yin-us e liabilit y concerns .P. 6


### -5

- I f a " manufacture r perceive s tha t th e adde dris k mentione d abov e ma yexis 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 throug hdirec t measure s o r throug hkeepin g th e overal l ris k in-us e a t acceptabl e level s throug hothe r desig nflexibilities . EPA' s analysi s identifie s an ddescribe s a numbe r o f thes e measures . Manufacturer s ca nmak e vehicle s safe r tha nthe yar e now ; a nonboar drequiremen t doe s no t increas e th e amoun t o f ris k a manufacture r nee dincu r o r accept . Manufacturer s ar e expecte dt o integrat e onboar d control s int o thei r fue l system s withou t compromisin g safet y

ige s whic hhav e bee n „>

_..^v . ^ ^v.., ^ ..V^_WXL O 

### (e.g. , changin g fro m fill) . Finally , i f a manufacture r chose s t o us e - „ c

### „ fue l bladde r t o contro l refuelin g emissions , thi s woul d eliminat e al l o f th e potentia l concern s raise drelativ e t o th e caniste r base d onboar dsystem , an dwoul dprovid e improvement s i nsafet yove r th e presen t fue l system . Othe r ke yconsideration s includ e safet yrelate dcost s an d th e leadtim e neede d t o implemen t onboar dcontrol s safely . Thi s analysi s estimate s tha t safet ycost s relate dt o implementin g onboar d 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 nimpact s ar e reasonabl yaccurate , ther e i s som e uncertaint yi nth e developmen t an d safet ycras htestin g cos t estimates . However , safet yrelate donboar dcost s ar e quit e insensitiv e t o eve nlarg e change s i nth e estimate s fo r developmen t an dsafet ycertification . I na genera l sense , EPA' s estimate s ar e supporte db yth e fac t tha t th e modification s neede dfo r presen t vehicle s t o insur e fue l syste msafet yin-us e hav e bee nacquire drelativel y inexpensively , an d vehicle s wit hevaporativ e emissio nsystem s compl ywit hFMVS S 30 1 today . Muc ho f th e groundwor k neede dt o implemen t a nintegrate d onboar d refueling/evaporativ e emissio n contro l syste msafel yha s bee ncomplete dan dman yo f th e sam eP. 7
-6

- technique s and approache s ca n b e used . Th e fac t tha t integrate d system s wil l b e use d mean s tha t som e 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 syste mcost . Safet y cost s contribut e abou t 2 5 percen t o f th e $2 0 cos t estimate d fo r a passenge r ca r onboar d system . Wit hregar d t o leadtime , give n th e magnitud e o f th e tas k an d pas t experienc e wit himplementin g evaporativ e emissio n and fue l syste m

integrit ystandard s (FMVS S 301) , thi s analysi s indicate s tha t 2 4 month s leadtim e i s adequate . However , EP Ai s coamitte d t o providin g th e leadtim e neede d t o implemen t onboar d control s safel yan d effectively , and i s ope n t o considerin g a shor t phase-i n o f control s t o assis t manufacturer s i n dealin g wit hproblem s o n uniqu e vehicl e models . Finally , th e onboar d system s whic hwoul d b e installe d o n HDGV s ar e quit e simila r t o thos e expecte d fo r passenge r car s an d ligh t trucks, eve n thoug hth 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 syste mintegrit ytestin g center s mor e o n evaluatio n o f fue l tan k integrit ytha n vehicl e cras htesting . Nevertheless , man yo f th e concern s raise d and addresse d abov e regardin g onboar d 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 ca n b e applie d safel yt o thi s clas s o f vehicle s withi n th e leadtim e lai d ou t abov e and fo r a reasonabl e cost .P. 8



### -7

- II . Introductio n EP Aha s receive d severa l comment s fro m the Moto r Vehicl e Manufacturer s Association , Automobil e Importer s o f Americ a (an d thei r membe r companies) , an d the Insuranc e Institut e for Highwa ySafet ywhic hhave expresse d variou s level s o f concer n abou t the potentia l safet yimplication s o f onboar d vapo r recover ysystems.[1,2 ] Also , som e preliminarycomment s regardin

g onboard safet yhave bee n receive d fro m NHTSA' s technica l staff . [3 ] Th e America n Petroleu mInstitut e (which ha s independentl ydevelope d severa l onboard-equippe d vehicles ) an d the Cente r fo r Aut o Safet yhave expresse d suppor t for the implementatio n o f onboar d vapo r recover ysystems.[4,5 ] Th e purpos e o f thi s repor t i s t o discus s an d analyz e the safet y related concern s raise d regarding onboard vapo r recovery systems . Moto r vehicl e manufacturer s fac e man ydifficul t technica l decision s in the design an d developmen t o f vehicl e system s an d th e integratio n o f thes e system s int o newvehicl e models . Th e difficult yo f thes e decision s ofte n arise s fro mthe fac t tha t thi s design , developmen t an d integratio n proces s require s the 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 hig hpriorit yin the design an d integratio n process . However , the proces s als o include s carefu l an d pruden t consideratio n o f the 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 sucha s fue l econom yan d emissions . I n eac hcase , manufacturer s mus t fin d the appropriat e balanc e o f al l the importan t criteria . Sinc e the design o f emissio n contro l system s ha s the potentia l t o affec t the overal l safet yo f vehicles , EP Aview s safet ya s a primary concern whe n evaluating the feasibilit yo f a n emissio n contro l device . EP Ai s presentl yevaluating the us e o f onboar d vapo r recover ysystem s "(onboar d systems ) a s a mean s o f controlling refuelin

g emissions . Th e potentia l safet yimplication s o f suc h control s requir e specia l consideration , becaus e implementing onboard system s wil l involve some mino r modification s o f the 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 key concern i n the design an d integratio n process . I n evaluating the safet yimplication s o f requiring onboar d controls , EP

Aha s applie d the philosoph ytha t no increas e i n overal l ris k shoul d be cause d or accepted , beyon d tha t now presen t wit htoday' s fuel/evaporativ e system . Thi s applie s t o bot hcomplianc e wit hthe applicabl e Federa l safet ystandard sP. 9

-8

- and th e in-us e safet yo f vehicle s equippe d wit honboar d systems . Th e followin g analysi s wil l sho wtha t straigh t forwar 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 , and tha t whil e fina l choice s regardin g exac t syste mdesign s li e wit hth e manufacturers , saf e fue l syste mdesign s ar e achievabl e b yall . 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 y improvement s coul d accompanyth e implementatio n o f onboar d controls . Th e importanc e o f evaluatin g th e safet yo f onboar d 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 EP At o consul t wit hth e Departmen t o f Transportatio n (DOT ) befor e requirin g th e us e o f onboar d vapo r recover y systems . Thi s requiremen t i s intende d t o insur e tha t al l safet yissue 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 followin g thi s introductio n (Sectio n III) , provide s a genera l descriptio n o f an onboar d syste mt o ai d i n th e understandin g o f an yrelate d safet yissues . Sectio n IV summarize s and provide s EPA' s analysi s o f th e comment s receive d regardin g th e desig n o f a saf e onboar d system , and Sectio n V discusse s onboar d effect s o n in-us e fue l syste m safety . 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 and leadtime . Heavy-dut ygasoline-fuele d vehicle s (HDGV ) pos e simila r ye t distinc t onboar d contro l syste msafet yissues , and Sectio n VI I addresse s thes e similaritie s and differences . Th e fina l sectio n provide s conclusions .P.1 0

III . Onboar d Contro l Syste mDescriptio n Befor e considerin g an ysafet yissues , i t i s importan t t o hav e a clea r understandin g o f onboar d refuelin g vapo r recover y system s (onboar d systems ) an d ho wthe ywork . Likewise , befor e considerin g th e characteristic s o f th e contro l system , i t i s importan t t o understan d th e natur e o f refuelin g 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 understandin g o f wha t refuelin g emission s ar e and ho w onboar d system s operat e t o contro l thes e emissions . I n manyrespects , 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 onboar d system s ar e mor e a n extensio n o r modificatio n o f curren t evaporativ e emissio n system s tha n 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 tw o system s wil l provid e a bette r understandin g o f th e incrementa l natur e o f onboar d system s relativ e t o curren t evaporativ e systems , and wil l b e usefu l i n assessin g th e design , cost , and leadtim e implication s o f implementin g 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 and ho wthe yar e currentl ycontrolled . Next , refuelin g emission s wil l b e discusse d and similaritie s betwee n onboar d system s and 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 tw o contro l systems . A . Evaporativ e Emission s Evaporativ e emission s emanat e fro mtw o basi c sources : th e fue l tan k and th e fue l meterin g syste m(eithe r a carbureto r o r a fue l injector) . Evaporativ e emission s arisin g fro mth e fue l tan k ar e primaril y"diurnal " emission s whil e thos e fro mth e fue l meterin g syste mar e terme d "ho t soak " emissions. * Thi s analysi s i s primaril yconcerne d wit hfue l tan k evaporativ e o r diurna l emission s sinc e thes e emission s ar e currentl y controlle d usin g a n 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 soa k emission s com e fro mth e fue l tank ; th e fue l tan k evaporativ e contro l syste mwoul d handl e thes e a s wel l a s th e diurna l emissions .P.1 1

-10

- Diurna l evaporativ e emission s consis t o f gaseou s hydrocarbon s tha t ar e displace d fro mth e tan k whe n fue l i n th e tank i s heated . Fue l heatin g ca n resul t fro mchange s i n ambien t temperatur e o r durin g vehicl e operatio n du e t o th e vehicl e exhaus t syste mand/o r recirculatio n o f fue l heate d b y th e engine . I n eithe r case , a s fue l i n th e tan k and vapo r abov e th e fue l hea t up , mor e o f th e liqui d fue l evaporates , and th e vapo r itsel f expands , thu s causin g hydrocarbo n vapo r t o b e release d int o th e atmospher e (unles s capture d bya contro l system) . Fue l volatility , size / o f th e vapo r space , initia l tank temperature , and th e degre e t o whic hth e tan k i s heate d ca n al l impac t th e quantit yo f hydrocarbon s emitted . Diurna l emission s occu r o n a t leas t a dail ybasis , and a syste m designe d t o contro l thes e emission s mus t b e capabl e o f handlin g repeate d evaporativ e emissio n loads . Sinc e th e earl y1970's , mos t vehicle s hav e com e 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 syste mtypicall yuse d o n today' s vehicles . B . Evaporativ e Emissio n Contro l Syste m Figur e 1 depict s a fue l tan k 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 syste m i s relativel ysimpl e i n desig n and require s ver yfe wcomponents . 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 and function . I n orde r t o effectivel ypreven t th e escap e o f fue l tan k vapor s t o th e atmosphere , a n evaporativ e contro l syste mmus t perfor mthre e basi c functions . First , th e syste mmus t limi t th e numbe r o f exit s throug hwhic hfue l tan k vapor s migh t escape . Second , th e exi t tha t doe s allo wfue l tan k 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 syste mmus 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 wa n evaporativ e emissio n syste m

perform s thes e thre e functions . Th e firs t functio n an evaporativ e emissio n syste mmus t perfor m

i s t o limi t th e outlet s throug hwhic hvapor s ca n escape . A s ca n b e see n i n Figur e 1 , ther e ar e onl ythre e opening s throug hwhic 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) , and 3 ) th e smal l limitin g orific e (approximatel y0.050-0.05 5 inch ) i n th e to p o f th e tank . Th e fue l tan k ca p i s designe d t o for ma tigh t sea l wit hth e fillnec k s o tha t onc e th e ca p i s secure d i n place , vapor s fro m th e fillpip e openin g and 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 throug hwhic h fue l tan k vapor s ca n escape . Thi s singl e availabl e outle t i s th e smal l limitin g orific e i n th e to p o f th e tank .PRESSURE/VACUU M RELIE F CA P EXTRENA L VEN T LIN E / " Figur e 1 Typica l Current Evaporativ e Syste m

-LIMITINGORIFIC E

-TLOAT/ROLLOVE R VALV E 

# L 3/8 " DIA . 8 ' LON G # PURG E VALV E

T O PURG E INDUCTIO N POIN T 1 LITE R CARBO N CANISTE R

1 4 GALLO NFUE L TAN KP.1 3



### -12

- As 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 the tan

k (a s lon

g a s th e fue l tan

k ca p i s secur e in place ) . Thi s pressur e build-u p i s slowl yrelieve d a s ga s tan k vapor s eventuall yforc e thei r wa

ythroug

hthe onl yavailabl e exit : the smal l limitin g orific e i n the to

p o f the fue l tan k whic hlead s t o the vapo r storag e devic e (charcoa l canister ) . B ylimitin

g the numbe r o f vapo r escap e passage s an d routin

g the evaporativ e hydrocarbon s t o a singl e point , the contro l systemha s successfull y performed the firs t o f it s thre e basi c functions . Befor e discussin

g the evaporativ e emissio n system' s secon d function , i t i s importan t t o understand wh ythe orific e in the to p o f the tan k i s s o limited in size . Th e orific e in the to p o f the tan

k i s ver

ysmal l i n siz e for 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 hydrocarbo n vapo r being forced throug

hthe limitin

g orifice . Second , the 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 the ven t line leadin g t o the evaporativ e emission contro l storag e devic e (charcoa l canister) , damag e coul d potentiall yoccu r t o the storag e medi a (charcoal) . However , the orific e i n the to p o f the tan

k i s s o smal l tha t liqui d passe s throug hi t a t onl ya ver yslo wrate . Essentiall y 

### onl yvapo r i s allowe d t o continu e t o the canister . Thi s poin t lead s t o the fina l reaso n for limitin g the siz e o f the ven t orific e t o sucha

n extent . Wer e the vehicl e eve r t o be in a rollove r accident , a ver ylittl e amoun t o f liqui d fue l woul d be abl e t o leak fro

mthe tan

k throug

hsucha smal l orifice . Thus , the limitin

g 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 m the fue l tan

k in the cas e o f a vehicl e rollove r an d thu s provide s the protectio n neede d t o compl ywit hFMVS S 301 . Th e cos t fo r thi s i s low . However , som e manufacturer s incorporat e a n additiona l valv e for adde d protection ; a

n exampl e i s show

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

n evaporativ e emissio n systemmus t perform . Onc e the vapor s escap e fro m th e fue l tan

k throughthe 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 , the hydrocarbon s ar e adsorbe d ont o activate d charcoa l wher e theyar e store d temporarily .P.1 4 -13

- Figur e2 STANDARD VERSIONS

ORIFIC E

FLOA T

SPRIN G

HIG H FLO

W FILTERE D

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 tline

. I n th e even tofextrem e vehicl e attitud e o rroll-over , th e floa twil l clos e th e caniste rven tline

. Afiltere d tan k

mounte d sprin g balance d floa tvalve i s availabl e tha tperform s th e sam e function s a s th e above sketche s excep tth e tan k sid e ofth e par

ti s filtere d t o preven tcontaminate s fro m enterin g th e partwhic h migh teffec tfloa tclosin g ofth e caniste rven tline

. Fo rhig h flo wapplication s tha trequir e a larg e volum e o fvapo rventing , suc h as fue l in jectio n applications , a hig h flo wvalve has bee n develope d tha thas more tha n twic e th e presen t flo wcapacit ywithou tloosin g othe rcritica l performanc e parameters
.



# FLOA TVALV E Borg-Warne rAutomotive , Inc . 70 7 Southsid e Or , Decatur , Illinoi s 62525 Phone 217/428-463 1 

# 43 7 SKETC H NUMBE RP.1 5

-14

- Th e workin g capacit yo f th e charcoal , th e quantit yand frequenc yo f th e evaporativ e emissions , and th e capabilit yo f th e syste mt o restor e it s workin g 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 and ho t soa k 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 , the ywil l remai n ther e unti l removed . Th e hydrocarbon s mus t b e strippe d fro m

th e charcoa l periodicall yi n orde r t o restor e enoug hworkin g 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 thir d basi c functio n o f restorin g 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 vacuumi s use d t o dra w hydrocarbon-fre e ai r throug hth e charcoa l canister . Hydrocarbon s store d i n th e caniste r ar e desorbe d int o th e ai r streamwhic hflow s int o th e fue l meterin g syste mvi 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 throug hnorma l combustio n i n th e engine . Thi s proces s "empties " th e canister , therebypreparin g 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 durin g vehicl e operation.[8,9 ] Avalv e locate d betwee n th e caniste r and th e fue l meterin g syste mi s opene d and close d a t opportun e time s t o contro l th e purg e proces s and limi t disturbance s whic haffec t engin e performanc e and exhaus t emissions . T o summarize , th e curren t evaporativ e emissio n contro l syste mperform s thre e basi c functions : 1 ) i t limit s th e exit s throug hwhic hfue l tan k vapor s ca n escape ; 2 ) i t trap s th e vapor s i n a storag e device ; and 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 ver ysimila r t o evaporativ e emissio n contro l system s becaus e the ymus t als o effectivel yperfor mth e sam e thre e basi c function s t o efficientl ycontro l refuelin g emissions . However , du e t o difference s i n th e quantit yo f vapor s and th e rat e o f generatio n o f evaporativ e and refuelin g emissions , equippin g vehicle s wit honboar d system s wil l requir e tha t som e mino r modification s b e mad e t o curren t fue l and evaporativ e emissio n contro l systems .P.1 6



### -15

- The nex t section provide s additiona l detai l regarding refuelin

g emission s t o hel p explai n th e fue l an

d evaporativ e syste mmodification s tha t woul d be require d t o equi p vehicle s wit honboard systems . C . Refueling Emission s Thre e processe s contribut e t o the releas e o f hydrocarbon s durin g a refuelin

g operation . Th e firs t tw o ar e collectivel y termed displacemen t losses , the third spillage . First , the hydrocarbo n vapo r presen t in the tan k i s displace d fro mthe fue l tan

k b yliqui d fue l entering throughthe fillpipe . I f the vehicl e fue l tan

k i s equippe d wit ha n externa l vapo r ven t line (a s show n in Figur e 1) , muc ho f the fue l tan k vapo r escape s vi a the externa l ven t line whic hi s connecte d t o the to p o f the fillpipe . However , i f no suc hvapo r passag e exists , th e vapo r make s it s wa

you t throug

hthe fillpip e concurren t t o the incomin g liqui d fuel . Hydrocarbon s ar e als o generate d an d released during refuelin g a s a resul t o f liqui d fue l evaporating a s i t i s dispense d int o the tank . Thi s secon d typ e o f displacemen t los s i s cause d b ythe turbulenc e in the liquid/ai r interfac e during the refueling proces s an d i s enhanced b

ythe highe r volatilit yo f the dispense d fue l relative t o the fue l in the tank . Athird sourc e o f hydrocarbo n refuelin g emission s i s the evaporatio n o f an y liqui d fue l spille d during the refueling operation . O f the thre e refuelin

g emissio n sources , the tw o displacemen t source s ar e generall ythe larges t (b yfar) , unles s a larg e spil l occurs . Becaus e the bul k o f refueling emissio n emanat e fro m withi n the fue l system , refuelin g emission s ar e in man yway s simila r t o diurna l evaporativ e emissions . Therefore , i t follow s tha t a n effectiv e onboard systemcan be designe d whic hutilize s the sam e 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 systems considere d b ymanufacturer s in thei r comment s incorporat e thi s approac ha s do the 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 In orde r t o contro l refueling emissions , onboar d system s mus t perfor

mth e sam e thre e basi c function s a s describe d previousl yfor diurna l evaporativ e emissio n systems . Thes e includ e limiting the numbe r o f exit s throughwhic hrefueling vapor s can escape , storing refueling emission s temporaril yin aP.1 7


### -16

- charcoa l canister , an d purgin

g the charcoa l caniste r o f the stored refuelin

g vapor s t o restor e it s capacit yprio r t o the nex t refuelin

g operation . Becaus e thes e thre e function s ar e s o simila r t o the thre e function s a diurna l evaporativ e emissio n contro l syste

mmus t perfor

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

ylead s t o the conclusio n tha t a

n onboard syste

mwoul d us e the sam e approac h an d simila r hardwar e t o tha t whic hi s currentl yused t o contro l evaporativ e emissions . Figure s 3 an d 4 depic t tw o representative onboard systems an d a compariso n wit hFigur e 1 show s tha t onboard control s ar e ver ysimila r in 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 the sam

e 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.) , the basi c difference s betwee n refuelin g an d evaporativ e emission s requir e a fe wadditiona l components , an d a n enlargemen t o f certai n existing hardwar e i s require d fo r the onboard system . Thes e ar e the ke

ydifference s betwee n the tw o systems . Befor e discussing the componen t addition s an d enlargements , a

n importan t aspec t o f the onboard refueling vapo r recover

ysystemmus t be introduced . Sinc e bot hemission s emanat e fro mthe sam

e 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 refuelin

g systemwer e incorporate d int o a vehicle' s fue l system , the curren t diurna l evaporativ e emissio n contro l syste mwoul d no longe r be 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 ythe system add s t o the vehicle' s fue l system . A

n entirel ynew , larger , mor e comple xsystem woul d no t be neede d i n additio n t o tha t whic hcurrentl y exists . Rather , the curren t contro l system woul d be modifie d t o be somewha t large r wit ha smal l increas e in the 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 the safet y design concern s associate d wit honboard system s have 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 be use d i n the 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 

## r\ NOZZL E ACTUATE D ROLLOVER/VEN T VALV E 

# r 5/8 " DIA . 3 ' LON G 

# liMECHANICA L SEA L 05 " DIA . LIMITIN GORIFIC E / <TLOAT/ROLLOVE R VALV E

1 4 GALLO NFUE L TAN K PURG E VALV E I

T O PURG E INDUCTIO N POIN T

3 LITE R CARBO N CANISTE R

0 0Figur e 4 Integrate d Evaporative/Refuelin g Syste m

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

-NOZZL E ACTUATE D ROLLOVER/VEN T VALV E 5/8 " DIA . 3 " LON G 3/8 " DIA . 5 ' LON G

3 LITE R CARBO N CANISTE R PURG E VALV E I V A 

# 4 /==^< l 1- T O PURG E INDUCTIO N POIN T

1 4 GALLO NFUE L TAN K

C OP.2 0



### -19

- 2 . Additions/Modification s t o Evaporativ e Emissio n Contro l Systems . The difference s betwee n onboard systems an d curren t diurna l evaporativ e emissio n contro l systems can be separate d int o tw o broad categories : 1 ) thos e related t o the sealing o f th e syste man d 2 ) thos e related t o the magnitud e an d frequency o f th e refuelin

g 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 the curren t evaporativ e systemmus t be increased i n siz e o r slightl ymodified . a . Addition s t o the Presen t System Diurna l evaporativ e emissio n contro l system s limi t the numbe r o f vapo r exit s b yusin g a fue l tan

k ca p t o clos e of f the fillneck . However , durin g a refuelin

g operation , the fue l tan k ca p i s no t in place , an d consequently , onboar d system s mus t relyo n som

e othe r typ e o f sealin g mechanis mt o preven t the escap e o f vapo r throug hthe fillnec k opening . Currently , tw o type s o f fillnec k seal s ar e availabl e fo r us e on onboar d systems - - liqui d an d mechanical . Liqui d fillnec k seal s utiliz e modifie d fillpip e design s t o rout e incomin

g gasolin e in sucha wa ytha t a colum

n o f gasolin e i s formed whic hprohibit s the vapor s in the fue l tan k fro m escaping t o the atmospher e vi a the fillneck . Whil e thi s may soun d somewha t complicate d a t first , the concep t i s fairl yeas y t o understan

d wit hthe hel p o f a picture . Severa l liqui d sea l configuration s have bee n developed , bu t on e design whic hha s bee n show

n t o be particularl yattractiv e fro mbot ha design an d cos t perspectiv e i s the "J-tube " (show n in Figur e 5).[16 ] A s fue l i s dispense d int o the fillneck , i t i s force d t o pas s throug hthe "U " shape d portio n o f the fillpipe . Aliqui d tra p i s formed in the "U " shape d portio n o f the fillpip e whic h prevent s vapor s fro mescaping vi a the fillneck . Th e "J-tube " extensio n coul d be mad e o f metal , plasti c o r hard rubber . Anothe r typ e o f fillnec k sea l whic hha s bee n show n t o be effectiv e i s the 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 hforms a clos e connectio n wit hthe inserte d fue l nozzl e an d thereb

yeliminate s an

yspac e in the fillnec k opening throughwhic hvapo r coul d escape . Whil e bot hth e liqui d an d mechanica l typ e seal s perfor mthe sam

e basi c functio n o f limitin g the availabl e vapo r exits , the liqui d typ e sea l i s inherentl ya simple r design .P.2 1 -20

- Figur e5

J-Tub eLiqui dSea l

J-TUB E T O CANISTE R

### -21

- Figur e6 Mechanica lSea l P.2 2



### MOOOTCATION S 

## ROTARYSEA L ROTAR YSEALTRA P DOO R

LEA D RESTRICTO R



## FIL LRP E MODIFfCATION S ROTARYSEA L ROTAPYSEA L TRAPDOO R

LEA D RESTRICTO RP.2 3

-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 tan k i f th e fue l nozzl e automati c shu t of f mechanis m

failed , o r i f fo r som e unusua l reaso n th e vapo r lin e leadin g t o th e charcoa l caniste r becam e 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 sealin g mechanis m- liqui d o r mechanica l - ca n b e use d t o preven t th e escap e o f refuelin g vapor s t o th e atmospher e vi a th e fillneck . b . Modification s t o th e Presen t Syste m Th e difference s i n th e frequency , magnitude , and rat e o f generatio n o f refuelin g and 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 , refuelin g emission s ar e produce d les s frequentl ybu t ar e large r i n magnitud e tha n 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 refuelin g emission s tha n i s neede d fo r evaporativ e emissions . Th e siz e o f th e caniste r neede d fo r an integrate d refueling/evaporativ e contro l syste mcanno t b e state d categoricall ysinc e ther e ar e severa l variable s whic hmus t b e considere d suc ha s purg e rate , charcoa l workin g capacity , and 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 syste mwoul d b e approximatel y3 time s a s larg e a s th e on e use d fo r th e presen t evaporativ e system.[17 ] Whil e th e large r caniste r doe s no t presen t an

ytechnica l problem s i t ma ycaus e packagin g problem s o n a fe wsmalle r vehicl e model s whic hcoul d lea d t o canister s bein g place d i n location s othe r tha n unde r th e vehicl e hood . Whil e virtuall yal l evaporativ e emissio n syste m canister s ar e no wlocate d unde r th e vehicl e hoo d ther e i s nothin g inheren t i n th e desig n o f a n onboar d syste mwhic h require s tha t canister s fo r integrate d system s als o b e locate d there . I n fact , ther e ma yb e som e cos t advantag e t o locatin g th e caniste r nea r th e fue l tan k sinc e th e amoun t o f large r vapo r line s ca n 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 , and performanc e characteristics .P.2 4

-23

- (2 ) Refuelin g Ven t Lin e Modification s Also , i n orde r t o accommodat e th e highe r vapo r flo wrate s associate d wit hrefuelin g emissions , a large r ven t lin e betwee n th e fue l tan k and charcoa l caniste r i s neede d alon g wit ha large r openin g i n th e to p 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 lin e t o th e caniste r associate d wit hth e evaporativ e syste mi s abou t 3/ 8 inch . Th e ven t lin e wit hth e integrate d evaporative/refuelin g syste m woul d b e approximatel y1/ 2 - 5/ 8 inc hi n diameter. [ 16 ] Th e large r ven t lin e (and large r openin g i n th e to p o f th e fue l tank ) introduc e a fe wadde d complexities . Unlik e th e limitin g orific e use d i n evaporativ e emissio n systems , th e large r openin g require d fo r an onboar d syste m 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 syste m t 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 and 8 , i s simpl e i n desig n and purpose.[14,18 ] I t act s t o remov e gasolin e droplet s fro mth e vapo r strea m and return s th e liqui d t o th e fue l tan k t o preven t liqui d gasolin e fro menterin g th e charcoa l canister . Man ydesig n approache s ar e availabl e i n additio n t o thos e show n here . Th e separato r itsel f ma yb e a distinc t component , o r it s functio n ma yb 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 durin g a n accident , and als o provid e th e benefit s o f a limitin g 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 and acciden t protectio n fo r th e fue l syste mi s primaril ya safet yissue . Asid e fro m

th e difference s discusse d above , onboar d and evaporativ e emissio n contro l system s ar e ver ysimila r i n design . The ybot hac t t o direct , trap , and consum e hydrocarbo n vapor . Onboar d system s requir e onl ya fe wadditiona l components , and becaus e the ycoul d b e integrate d int o vehicl e fue l system s t o handl e bot hrefuelin g and evaporativ e emissions , overal l contro l syste mcomplexit 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 onboar d 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 and knowledg e gaine d i n implementin g 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 designin g and developin g saf e integrate d evaporative/refuelin g systems .P.2 5 -24

- Figur e7 

### VAPOR-LIQUI D SEPARATO R

Mountin g Hole s


# ^ z £ FloatWeigh tFigur e8

VAPO R OU T

J-Un nriiii.intiiii111 IJ 1111$yi.i.i.if.i'n .• t .9 l ^.i,......'A ADHESIV E SEA L

i—.7 5 HOS t TY R

• - VAPOR/UOUJ D I N

T UQUJD/COfcDENSAT E RETUR N 

# o 1 0 UCM D REUE F SLOT

MOUNTIN G TAB S (3 ) , —i. . ui 

### r, • , . / 

# ¥

z.o _ i I r o u i I

A R OPtZH

6KU . fOA M A R

W MES H FABRI C UPPE R riOUSlMa LDVMC R H0U5IN 6 MtCWPTN M NVLO M PLASTI C PLA6TI C •ATMA L VAPO R - LIQUI D SEPARATO R U1LL1 WA.«OCIATI> . W C UttMW . M P >»*> « n/tfl/a d *«**•••FU LL 

# I I^Ui

.P.2 7


### -26

- IV . Design Consideration s for a Saf e System A s wa s discusse d previously , severa l commenter s hav e expresse d concer n regardin g the potentia l safet yimplication s o f onboar d systems . Areviewo f thes e comment s indicate s tha t thes e concern s fal l int o tw o broad areas : the design o f a saf e onboard systeman d effect s o n in-us e fue l systemsafety . Concern s in the firs t are a wil l be addresse d in thi s section . Th e sectio n whic hfollow s (Section V ) wil l addres s the late r are a o f concern . Comment s receive d regardin g the design o f a saf e onboar d systemfal l in thre e categories : 1 ) safet ytes t design requirements , 2 ) safet yeffect s o f tampering an d defect s an

d 3 ) refuelin

g operatio n safety . EPA' s summar yan d analysi s o f the comment s in eac hcategoryi s presente d below . A . Safet yTes t Design Requirement s 1 . Introductio n Befor e analyzing the safet ytes t design requirement s i t i s interesting t o look a t fue l system safet yfro

m a n in-us e perspectiv e fo r 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 som e typ e an

d abou t 0. 5 percen t o f the rollove r accident s resul t i n a fire . [19 ] Thi s result s in 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 rear en

d collision s lea

d t o a vehicl e fire.[19 ] Thus , fro m a n in-us e perspective , vehicl e cras hfire s ar e uncommo n events . On e o f the 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 the overal l integrit yo f the vehicle' s fue l system . T o insur e fue l system integrit 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 o r less , mus t compl y wit hFedera l Moto r Vehicl e Safet yStandard (FMVSS ) 301.[20 ] 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 ) at 2 0 rnph . 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 period o f fiv e 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 occu r in FMVS S 30 1 testing .P.2 8

-27

- Alon g thes e lines , tw o issue s exis t regardin g th e desig n o f an onboar d syste mcapabl e o f passin g FMVS S 301 . Thes e includ e rollove r protectio n and th e crashworthines s o f ke y onboar d syste mcomponent s and 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 tan k and charcoa l canister , and 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 som e curren t fue l tank s als o require s a 1/2 " orifice , manufacturer' s onboar d syste m

design s ma yincorporat e a rollove r protectio n devic e t o protec t agains t fue l leakag e durin g a n FMVS S 30 1 rollove r tes t eve n thoug hpresen t design s d o not . Also , vehicl e crashe s presen t th e possibilit yo f direc t o r indirec t damag e t o fue l syste mcomponents . I n som e case s thi s damag e coul d lea d t o a fue l lea k o r increas e th e potentia l fo r a vehicl e fir e i n som e othe r portio n o f th e fue l system . Thu s a properl ydesigne d onboar d syste mmus t no t compromis e th e crashworthines s o f th e syste mand ke ycomponents . 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 refuelin g 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 and othe r interest s whic h coul d adequatel yperfor mthi s safet yfunction . Severa l o f thes e ar e discusse d below . On e desig n whic hha s bee n propose d b ysevera l source s ca n 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 and i s locate d nea r th e to p 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 byth e insertio n o f a fue l nozzle . Wit hth e valv e open , a clea r passag e throug hth e ven t lin e i s availabl e t o allo wfo r th e routin g o f refuelin g vapor s t o th e charcoa l canister . Othe r tha n durin g refueling , th e valv e remain s close d and effectivel yeliminate s th e potentia l fo r fue l leakag e throug hth e refuelin g ven t lin e durin g a rollove r accident . Figure s 9 thoroug h1 5 sho wfiv e differen t nozzl e actuate d valv e assemblie s capabl e o f performin g th e rollove r protectio n function.[13,15,18,21 ] Figure s 9 throug h1 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 ventin g o f fue l tan k vapor s durin g refuelin g and whe n th e nozzl e i s remove d th e ven t lin e woul d b e closed .Figur e 9 

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



### kil l -L S 

### )

SHUT-OF F %*LV E HS

-"— ' "~^*- ^ \ . ^ \

J ' V(^^^X . ^rm

2/^r



# s /

/

SCA

L / ^

1—

LEADE D FUE L \ . JT

DEFLECTO R -GA S CA P

RELIE FUALV E ,-28-Figur e1 0 

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

T O CANISTE R -

VAPO R FRO M TAN K LIQUI D STO P LEADE D FUE L OEFLECTO R

VO I

OVERFILL RELIE F VALVE

SEA L FUE L NOZZL EFigur e1 1 

## LIQUI D SEA L SYSTE M TAN KVEN TVALV E ASSEMBL Y (DURIN G NORMA L VEHICL E OPERATION I

T O CANISTE R - SHU TOF F VALV E

LEADE D FUE L DEFLECTO R i O J o I
GA S CA P



### PFigur e1 2 

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

T O CANISTE R -

VAPO R FRO M TAN K SHUT-OF F VALV E LEADE D FUE L

OEFLECTO R

FUE L NOZZL E i O JFigur 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 O J t o IP.3 4

r-\ C U

• H &4 -33 -

u I t. 

## I o 

## r if ? I 

# a\ U

J



## z UJ U . U J OCP.3 5 -34

- Figur e 1 5

"Toyot a Concept "



# Rubbe r Sea l

t o Caniste r fro mFue l \ . Tan k v

# '

/ / 

# t o Fue l Tan k Refuelin g Nozzl eP.3 6

-35

- Also , whil e a rollove r protectio n devic e migh t b e necessary , i t i s interestin g t o not e tha t manycurren t productio n passenge r ca r and ligh t truc k model s (mostl ysid e fill ) emplo ya n externa l vapo r ven t lin e o f abou t 1/2 " diamete r tha t connect s th e fue l tan k t o th e to p o f th e fillpip e (se e Figur e 1) . Thi s externa l ven t lin e i s approachin g th e siz e neede d fo r a refuelin g ven t line , and 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 , addin g a rollove r protectio n syste mt o thes e vehicle s ma yactuall 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 , and ca n b e integrate d effectivel y int o th e vehicl e desig n fro mbot hsafet yand operationa l perspectives . 3 . Component/Syste mCrashworthines s Th e secon d issu e regardin g safet ytes t desig n requirement s involve s th e crashworthines s o f th e ke ycomponent s o f a n 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 , canister ) and th e structura l integrit yo f th e vapo r lin e (an d connections ) whic hma yexis t betwee n th e to p o f th e fue l tan k and th e rollove r valve . Aproble mi 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 and mus t b e addresse d i n prope r syste mdesign . Eac ho f thes e concern s i s discusse d below . However , befor e beginnin g thes e discussions , i t shoul d b e note d tha t component/syste mcrashworthines s i s no t a t al l a ne w concern . Manufacturer s mus t addres s thes e sam e concern s i n th e desig n o f th e curren t evaporativ e emissio n systems . Give n th e similarit yo f onboar d refuelin g and evaporativ e controls , and 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 desig n consideratio n fo r 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 desig n 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 i n a collision .

### -36

- 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 decreasin

g the structura l integrit yo f the fillpip e whil e providin

g crashworthines s fo r the valve . Fo r example , i t i s wort hnotin

g tha t vehicl e manufacturer s have deal t wit hsimila r problems in thei r design s o f fillpipes , externa l vapo r ven t lines , an

d ga s caps , an

d in fact , on e woul d no t expec t the nozzl e actuate d rollove r valve t o be an ymor e susceptibl e t o damag e than thes e components . A s wa s mentione d previously , the 1/2 " externa l ven t line lie s i n thi s sam e are a o n the vehicle , an d ye t manufacturer s have include d suchven 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 be cognizan t o f the structura l integrit yo f the vapo r line an d vapo r line connections , i f any , betwee n the fue l tan k an d the rollove r valve . Thes e woul d have t o be designe d t o withstand the stresse s whic hmigh t occur in a cras hin orde r t o maintai n fue l syste mintegrity . However , ther e i s no significan t engineering challeng e t o accomplishing thi s objective . Th e integrit yo f thi s portio n o f the vehicle' s vapo r line can be assure d throug hus 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 , routin g o f thi s portio n o f vapo r line i s anothe r design 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 the line i s protecte d fro mabrasio n an

d norma l wea r an

d tha t i t i s no t in a vulnerabl e locatio n i n the even t o f a collision . Thi s i s considere d straightforwar d give n tha t o n integrate d system s the refueling vapo r line now replace s tha t use d fo r contro l o f diurna l evaporativ e emissions . Simila r routing s woul d be expected . Vapo r line integrit yan

d connection s i n 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 som e vehicl e model s now us e a flexibl e inser t betwee n the fillpip e an d fue l tan

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

p o f the fue l fillpip e an

d the fue l tan

k (se e Figur e 16) . Thes eFigur 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% " i U l IP.3 9


### -38

- connectioh s ar e subjec t t o the sam e performanc e requirement s a s woul d b

e neede d for onboard systemvapo 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 have bee n incorporate d safely . Th e manufacturers ' experienc e wit hcurren t vehicl e evaporativ e an d fue l system s described above demonstrate s tha t vapo r line an d vapo r line connection s can be mad e t o withstand the stresse s whic hoccu r in a vehicl e accident . c . Charcoa l Caniste r Concern s regardin

g the crashworthines s o f the charcoa l caniste r cente r o n the possibilit ytha t a caniste r rupture d i n a n acciden t coul d presen t a fir e hazard i f a n ignitio n sourc e exist s nearby . Eve n i f the ruptur e o f the integrate d refueling / evaporative caniste r occurre d i n some cases , the potentia l hazard shoul d no t be overstated . Whil e the refueling loa d t o th e caniste r i s large r than the evaporativ e load , afte r the firs t fe

wmile s o f driving the caniste r woul d be purge d suc h tha t the amoun t o f vapo r remaining in the caniste r i s essentiall ythe sam e a s tha t presen t in curren t evaporativ e emissio n canister s alone. * Thu s i t coul d be argue d tha t the rea l hazard , i f any , i s no t significantl ydifferen t than tha t no wfoun d on presen t systems . Thus , i t i s hard t o perceiv e an y added ris k fro

mthe us e o f a large r charcoa l canister . Nevertheless , i f a manufacture r believe d tha t the caniste r posed to o grea t o f a potentia l risk , the ris k coul d be eliminate d throughplacemen t o f the caniste r in a protecte d are a sucha s the rear o f the engin e compartmen t o r i n some underbod

yare a a s ha s bee n suggeste d b ysome manufacturers.[12,13 ] In mos t case s i t i s expecte d tha t manufacturer s woul d simpl yplac e the integrate d refueling/evaporativ e caniste r wher e the presen t caniste r i s nowlocated ; i n thes e case s no ne wdesign issue s reall yexist .

Du e t o the natur e o f the charcoa l use d t o tra p hydrocarbo n vapors , an

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

ysafet yrisks.[9 ]P.4 0

-39

- d . Summar y I n summary , curren t fue l and evaporativ e emissio n system s mus t mee t th e sam e FMVS S 30 1 requirement s and muc ho f th e experienc e gaine d i n designin g and buildin g curren t system s ca n b e directl yextrapolate d t o implementin g 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 engineerin g solution s exis t t o addres s an ypotentia l safet ydesig n concerns , and tha t onboar d system s ca n b e incorporate d int o th e vehicle' s fuel/evaporativ e syste m withou t compromisin g fue l syste mintegrit yo r reducin g th e vehicle' s abilit yt o pas s FMVS S 30 1 requirements . Whil e a n onboar d syste mca n b e designe d t o provid e fue l syste mintegrit ybot hi n FMVS S 30 1 testin g and in-use , i t i s pruden t t o conside r th e possibilit yo f tampering , malmaintenanc e and defect s wit hthes e systems , and mean s t o addres s anypotentia l problem s whic hma yexist . Thes e issue s wil l b e addresse d next . B . Tampering , Malmaintenance , an d Defect s Eve n i f a syste mi s designe d properl yand function s safel y unde r "normal " and "extreme " in-us e conditions , som e questio n remain s a s t o th e potentia l effect s o f tampering , malmaintenance , and defect s o n onboar d syste msafety . Tamperin g involve s th e intentiona l disablemen t (partia l o r total ) o r remova l o f a componen t withi n th e system . Malmaintenanc e i s th e incorrec t applicatio n o f a prescribe d maintenanc e procedure , and defect s involv e th e imprope r operatio n o f a prescribe d syste mo r syste mcomponen t cause d b y design , manufacturin g o r assembl yerrors . A n onboar d syste mi s expecte d t o b e essentiall y maintenanc e fre e (n o schedule d maintenance ) a s ar e curren t evaporativ e emissio n systems . Thu s th ^ focu s o f safet y concern s turn s mor e towar d th e effect s o f defect s and tampering . Althoug hbot hdefect s and tamperin g ar e uncommon , the yar e possibl e and som e though t mus t b e give n t o designin g system s whic hminimiz e th e likelihoo d o f thes e event s and th e safet yeffect s i f the yd o occur . 1 . Defect s First , wit hregar d t o defects , th e primar ysafet yrelate d concer n deal s wit hth e possibilit ytha t defect s i n th e operatio n o f on e o r mor e component s o f th e onboar d syste m 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 and rollove r valve .P.4 1



### -40

- Sinc e onboard syste mcomponent s sucha s the liquid/vapo r separator , purg e valve , an d charcoa l caniste r ar e ver ysimila r t o thos e use d in evaporativ e systems , on e metho d t o asses s the potentia l safet yeffect s o f defect s i s t o reviewthe experienc e seen wit hevaporativ e systems . In a n effor t t o quantif ythe potentia l for defec t problem s regardin g onboard systems , thre e differen t compute r file s provide d b yNHTSAwer e reviewe d fo r evidenc e a s t o defect s pertainin g t o the evaporativ e emissio n syste mwhic hcoul d impac t vehicl e safet yin-use.[22 ] Th e file s reviewed 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 , light truck , an d heavy-dut ygasoline) . Areviewo f the recal l file s reveale d onl y1 2 case s tha t coul d b e eve n remotel ylinked t o the evaporativ e emissio n systemou t o f a n estimate d 3,00 0 familie s certifie d wit hevaporativ e emissio n systems . Servic e bulleti n report s for dealer s adde d a n additiona l 2 1 case s for a tota l o f 3 3 possibl e problem s ou t o f ove r 300 0 families . Non e o f thes e wer e identifie d a s having caused a

n accident ; the vas t majorit ywer e mor e emissio n system performanc e than safet ydefects . Finally , a reviewo f the 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 . In onl ya fe

wo f the owne r complaint s di d safet yproblem s actuall yoccur , an d no significan t damag e wa s reported . O n a percentag e basi s thes e potentia l problem s ar e ver ysmall . Two othe r valuabl e observation s can be draw n fro m a revie w o f thes e files . Problems/complaint s have 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 the similarit ybetwee n onboar d refueling an d evaporativ e emissio n controls , an d the fac t tha t the two systems wil l be integrate d in mos t cases , muc ho f thi s experienc e wil l be directl ytransferabl e t o onboard system s an d thu s improve in-us e performance . Second , the reviewo f th e owne r complaint s file s indicate d no trend s othe r than thos e related t o improvement s in newe r mode l yea r vehicles ; thu s no systemati c problem s in component s o r system s wer e evident . Further , i t i s importan t t o not e tha t the verymechanism s used t o generat e the file s for 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 effectiv e i n dealing wit hproblem s raise d a t the dealerships , an d owne r complaint s assis t the manufacturer s an d NHTSAi n assessing the nee d t o conduc t voluntaryo r mandatoryrecalls . Finally , t o plac e the potentia l fo r defec t problem s fro m onboard system s in context , i t shoul d be note d tha t the onboar d ris k i s essentiall yincrementa l t o tha t nowsee n fo r evaporativ e systems , sinc e in mos t case s the refueling an d evaporativ e system s woul d be integrated . O n a n incrementa l basis , the frequenc yo f defect s woul d likel ybe unaffected .P.4 2

-41

- Finaily , sinc e a rollove r valv e coul d b e use d o n som e onboar d syste mdesign s specificall yt o enhanc e safet yand the y ar e no t use d o n curren t vehicles , i t i s wort hdiscussin g 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 engineerin g technique s permi t th e developmen t and productio n o f highl yreliabl e valve s and statistica l qualit ycontro l technique s ar e availabl e t o insur e tha t productio n valve s mee t desig n 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 end 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 providin g rollove r protectio n and i t woul d effectivel ybloc k th e refuelin g ven t lin e and mak e refuelin g 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 . Also , rollove r valv e failur e migh t b e on e componen t o f a n onboar d syste mwhic hcoul d b e incorporate d int o onboar d vehicl e diagnostic s and thu s allo wth e operato r notic e o f th e proble mwhe n i t occur s and provid e a n opportunit y fo r 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 achievin g bot hprotectio n and repair , and tha t th e othe r measure s discusse d abov e woul d assis t i n eliminatin g o r addressin g anyin-us e defects . 2 . Tamperin g Asecon d are a o f potentia l safet yproblem s involve s th e effect s o f possibl e syste mtampering . Whil e severa l type s o f tamperin g occu r 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/o r remova l o f th e charcoa l canister , migh t b e a safet yproble mfo r onboar d systems . Thi s typ e o f tamperin g pose s a possibl e safet yhazar d becaus e durin g th e refuelin g 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 ha d bee n located . Whil e th e gasolin e vapo r mixtur e reachin g th e caniste r locatio n i n thi s situatio n woul d b e wel l abov e th e uppe r flammabilit ylimit , i t woul d briefl yb e flammabl e a s th e vapo r dissipate s and a t th e air/vapo r transitio n zones . I f a spar k o r 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 onboar d syste mdesign .P.4 3

-42

- Tabl e 1 Type s o f Tamperin g Problem s An d Typica l Rate s o f Occurrenc e Rat e o f Proble m Occurrenc e (% ) Ga s Ca p Remove d 1.2 % Caniste r Vacuu mDisconnecte d 1. 7 Ca p Remove d & Caniste r VacuumDisconnecte d 0. 1 Caniste r Remove d 0. 3 Non-vacuumCaniste r Disconnectio n 0. 2 Tota l Disablement s 3.5 %

Tamperin g rate s calculate d fro mth e combine d dat a fro mth e EP ATamperin g survey s performe d i n 1982 , 198 3 and 1984 . (9,14 2 vehicles )P.4 4

-43

- 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 no wexis t wit hevaporativ e emissio n canister s bu t a safet yconcer n regardin g tamperin g wit hevaporativ e emissio n syste mcanister s ha s no t surfaced . Second , usin g 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 onboar d refueling/evaporativ e canisters . A s i s show n i n Tabl e 2 , curren t averag e caniste r tamperin g i s onl yabou t 3 percen t o f al l vehicles , and 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 , tamperin g coul d b e furthe r discouraged . Further , th e potentia l proble mcoul d b e reduce d throug h prope r placemen t o f th e caniste r i n a locatio n distan t fro many 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 hsom e evaporativ e canisters ) o r i n som e underbod yare a a s ha s bee n suggeste d b ysom e manufacturer s fo r packagin g reasons . Placin g th e caniste r i n an underbodyare 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 tamperin g i s infrequent , and mean s exis t t o discourag e suc haction s eve n further , goo d engineerin g judgmen t dictate s tha t canister s no t b e place d i n a locatio n wher e tamperin g 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 necessar yt o reduc e tampering , and tha t refuelin g 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 . 3 . Summar y I n summary , neithe r componen t defect s o r tamperin g nee d creat e th e potentia l fo r in-us e safet yrisks . Ther e i s n o evidenc e t o indicat e tha t possibl e defect s i n othe r onboar d syste m component s woul d lea d t o safet yproblems . Ther e ar e ver yfe wdefects ' wit hpresen t evaporativ e emissio n systems , and sinc e i t i s likel ytha t refuelin g and evaporativ e emissio n system s woul d b e integrated , th e overal l defec t rat e i s likel y t o b e n o 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 and t o insur e rollove r protectio n i n th e unlikel yeven t o f a valv e failure . Whil e caniste r tamperin g effect s mus t b e considered , i t shoul d b e note d tha t i t presentl yi s uncommon , and thi s lo w rat e i s expecte d t o continu e fo r onboar d systems . Also , tamperin g coul d actuall ydecreas e throug hjudiciou s caniste rP.4 5

-44

- Tabl e 2 Caniste r Tamperin g Surve yResult s

ByYear * Passenge r Ca r and Ligh t Truck* * Yea r % Tampere d 197 8 3 197 9 2 198 0 N o Repor t 198 1 2 198 2 2 198 3 5 198 4 3 198 5 4
Av g

* Moto r Vehicl e Tamperin g Surve y- 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 6

-45

- 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 locatio n wher e tamperin g coul d lea d t o a safet yproblem , and i t i s expecte d tha t thi s approac hwoul d b e followed . An onboar d syste mdesig n mus t als o includ e consideratio n o f potentia l effect s o n th e safet yo f refuelin g operations . Thi s i s discusse d i n th e nex t section . C . Refuelin g Operatio n Safet y 1 . Fue l Tan k Overpressur e Durin g 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 tan k durin g th e refuelin g o f a vehicl e equippe d wit han onboar d system . Wheneve r a syste mi s designe d t o b e "sealed " fro mit s environment , som e forethough t mus t b e exercise d t o evaluat e th e possibilit yand consequence s o f an overpressur e withi n th e system . Althoug ha n onboar d syste mdoe 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 refuelin g vapo r ven t line . I f fo r som e unusua l reason , th e ven t lin e wer e t o becom e full yo r partiall yblocke d o r th e nozzl e automati c shut-of f mechanis mfaile 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 ha n onboar d syste mutilizin g a mechanica l sea l a s illustrate d i n Figur e 3 . Wit ha liqui d sea l syste m(se e Figur e 4) , exces s pressur e canno t buil d up i n th e tank durin g refuelin g becaus e fue l woul d simpl yflo wou t th e fillnec k openin g (th e sam e wa yi t currentl ydoes ) and th e nozzl e operato r coul d the n sto p th e fue l flow . Liqui d sea l system s woul d functio n i n th e sam e manne r a s curren t fue l systems . Fro m

th e nozzl e operator' s viewpoint , th e refuelin g operatio n remain s th e same . 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 o r ven t lin e blockage , thi s devic e woul d eliminat e potentia l tan k overpressurizatio n b yopenin g a n "emergency " passag e t o th e atmospher e throug hwhic hpressurize d vapo r and anygasolin e woul d spil l ont o th e pavemen t o r som e othe r locatio n noticeabl e t o th e nozzl e operator . Thi s spillag e woul d mak e th e fue l pum p operato r awar e o f th e proble mand fue l flo wcoul d b e stoppe d withou t causin g damag e t o th e fue l syste mo r causin g fue l t o spitbac k o n t o th e operator .P.4 7

-46

- Ther e hav e bee n severa l differen t design s suggeste d fo r suc hpressur e relie f devices . Asampl e desig n i s shown i n Figur e 1 7 whic hwoul d b e incorporate d directl yint o th e desig n o f th e 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 resum e norma l refuelin g actions . (Th e nee d fo r promp t repai r woul d hav e positiv e safet yand ai r qualit ycomplications. ) 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 som e othe r componen t o f th e syste msuc ha s th e rollove r valve . Anyoverpressur e concern s ca n b e eliminate d throug ha simpl e pressur e relie f devic e suc ha s these . 2 . Pre-Refuelin g Overpressur e Effect s Anothe r potentia l safet yissu e raise d relatin g t o refuelin g operation s ha s t o d o wit hth e "U " ben d i n th e "J-tube " fillnec k seal . I f th e tan k ven t becam e blocked , and pressur e buil t up 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 standin g i n th e "U " ben d coul d b e spi t bac k ou t th e fillpipe . Thi s concer n ca n b e easil yaddresse d b ydrillin g a smal l hol e i n th e botto mo f th e "U " ben d (se e Figur e 4) , whic hwoul d allo wan

yfue l lef t standin g i n th e fillpip e subsequen t t o a refuelin g 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 dispensin g rate s see n in-use , thi s hol e ca n b e size d t o quickl yprovid e drai n capacit yand stil l provid e th e sea l neede d durin g refueling . Byevacuatin g th e column o f fue l lef t standin g i n th e fillpipe , th e potentia l fo r spitbac k t o occu r upo n remova l o f th e fue l tan k ca p woul d b e eliminated . 3 . Summar y Th e analysi s presente d abov e demonstrate s tha t simple , straightforwar d engineerin g solution s exis t fo r th e specifi c concern s raise d b yth e commenters . I n al l cases , manufacturer s hav e a numbe r o f desig n option s availabl e t o addres s any specifi c concerns .Figur e1 7

6 0 *

l RIVET, TYP . Z PLACE S

BOTTO M VIE W 2.0 0

1.0 0 REF . 2.0 0 (MA . OETAI LB FLAPPE R VALV E

- 1.0 0 OIA .

.O6M1N . I

TO P VIE W I

- J I

SECT . A- A

NOTES : ^REMOV E AL L BURR S AN D SHAR P EJX.ES . .0 1 R MAX . O R CHAMBER . A , ROTAR Y3HAF TSEA L I S APURCHASE D PART . PAR THO. r&D . A ^ I UPPE R RETAINE R I

"B 7 VALV E FLAPPE R ROTAR YSHAF TSEAL . LOWE R RETAINE R Ofscat ? TW N STEE L VITO N ' STEEL . PURCHASE D

view . NOZZL E SEAL/REUE F VALV E

ASSEMBL Y MUELLE R ASSOCIATES . IM C B>tll«»<W . M P 0 * H l l •ht>M XALE" . FUL L |pAO t | O f| ,

O DP.4 9



### -48

- V . In-Us e Fue l System Safet y 1 . Summaryo f Concern s Some concer n ha s bee n expresse d tha t an ytim e a system increase s in siz e or complexity , the potentia l for a failur e withi n the systemals o increases . Applying thi s line o f thinkin g 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 systemsafet ybecaus e severa l component s ar e large r an

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

n increas e in componen t size/numbe r coul d lea d t o safetyproblems . 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 ythe numbe r o f vehicl e cras hfire s tha t occur eac hyear . I t ha s been argue d tha t vehicle s equippe d wit ha n onboard 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

ysom e unquantifiabl e (presumabl ysmall ) amount . Thus , i t follow s tha t becaus e som e in-us e situation s diffe r fro m FMVS S 30 1 tests , onboard system s mus t no t onl ybe designe d t o be capabl e o f passing Federa l safet ystandards , bu t thes e systems mus t als o be designe d s o a s no t t o increas e in-us e ris k for 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 a n appropriat e leve l o f safetyan

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 howt o addres s thi s issue , i t i s valuabl e t o discus s howsafet y concern s ar e integrate d int o the overal l vehicl e design an d developmen t process . First , safet yi s a n integra l par t o f the design 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 sucha s performance , styling , weight , cost , an

d othe r factors . I t i s generall yaccepte d tha tP.5 0

-49

- n o technologica l constraint s exis t whic hwoul d preven t th e productio n o f a nearl y"fire-proof " vehicle , and certainl y vehicle s coul d b e mad e safe r tha n the ycurrentl yar e a s evidence d bynumerou s "safet ycar " designs.[23 ] However , cos t an d othe r consideration s ar e vali d and the ypreven t "zero " ris k (o r 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 'Sherma n Tanks '

.. . a s suc hvehicle s woul d neithe r serv e th e need s o f societa l safety , mobility , o r economy."[24 ] Thi s sam e logi c and ris k managemen t proces s applie s t o fue l syste msafety . Factorin g safet yint o fue l syste mdesig n i s a complicate d proces s tha t involve s numerou s tradeoff s and compromise s a s above . Fue l syste mdesign s ar e no t al l alike , and fue l syste msafet yconsideration s var yfro mon e desig n t o another . Fo r example , fue l tan k siz e and 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 , and 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 tha n rea r fil l tanks , and consequently , rea r fil l fue l tank s ar e graduall ybein g 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 and conflictin g 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 som e ris k i s accepted . Anothe r interestin g exampl e lie s i n th e are a o f fue l syste m externa l plumbin g suc ha s emissio n contro l vapo r line s o r externa l ven t line s alon g th e fillpipe . A t on e tim e adde d pipin g connection s simila r t o th e externa l vapo r ven t line s tha t appea r o n som e o f today' s vehicle s wer e characterize d a s a n unacceptabl e adde d safet yris k b yGenera l Motors.[25 ] However , toda ytha t sam e manufacture r incorporate s a n externa l vapo r ven t lin e int o man yo f it s vehicle' s fue l systems . Thi s particula r desig n chang e illustrate s a ver y significan t aspec t o f fue l syste msafety . Eve n thoug hconcer n existe d 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 appea r 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 ca n b e managed . Safet ydoe s no t hav e t o b e a n obstacl e t o fue l syste mimprovement s o r modifications . Th e technolog yt o reduc e safet yrisk s i s currentl yavailable , and th e degre e t o whic hi t i s utilize d depend s o n ho wmuc hris k a manufacture r i s willin g t o accept .P.5 1



### -50

- A s illustrate d in th e discussion s above , manufacturer s accep t or manag e varying amount s o f ris k in orde r t o strik e a balanc e o r compromis e wit hal l o f the importan t design criteria . Clearl ysafe r vehicle s coul d be made , an d th e amoun t o f in-us e ris k reduced . A s consideration s change , the amoun t o f ris k accepte d ma yals o change . Ofte n the leve l o f acceptabl e ris k ma ybe mor e constraine d b yin-us e liabilit y concern s than governmen t safet ytests . Fo r example , cras h testin g result s recentl yrelease d b ythe Insuranc e Institut e for Highwa

ySafet yshowa wid e rang e o f performanc e on vehicle s designe d t o mee t the NHTSAbumpe r standards . Anumbe r o f vehicle s performe d bette r than require d b ythe standard s an d performanc e varie d b yvehicl e model.[26 ] Some manufacturer s chos e t o incorporat e safe r design s o n som e model s for liabilit y an d perhap s marketabilit yreasons . Similarly , the safet yo f a n onboard system

o n in-us e vehicle s wil l depen d o n the design decision s mad e b yth e manufacturers . Onboar d system s woul d increas e the 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 the safet yo f thes e component s in FMVS S 30 1 testing ma yno t necessaril ybe indicative o f in-us e performance . However , addin g thes e system s doe s no t need t o affec t the leve l o f ris k a manufacture r i s willing t o or can afford t o accept . A s wit han yothe r system

change , manufacturer s woul d integrat e onboard system s int o thei r vehicles ' fue l system s withou t increasing overal l system risk , an d clearly , ther e ar e no inheren t technica l constraint s prohibiting themfro m doing so . Further , ther e i s littl e meri t t o the assertio n tha t a n onboard systemmus t be inherentl yles s saf e than a n evaporativ e emissio n systembecaus e i t i s mor e "complicated" . Adding a few component s an

d enlarging a coupl e o f other s present s no ris k whic hcanno t be manage d t o level s nowdeeme d acceptable . A s a matte r o f fact , man yo f the 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 have increase d vehicl e engin e complexit ytremendousl yove r previou s systems , ye t ther e i s no evidenc e tha t thes e system "complications " hav e jeopardize d safety . I n fact , manufacturer s ar e nowconsidering compute r control s fo r othe r vehicl e system s suc ha s the suspensio n an d handling , wit hthe direc t purpos e o f improving vehicl e safety.[27 ] Amor e complicate d systemdoe s no t impl ya les s saf e on e i f give n prope r consideratio n during design .P.5 2


### -51

- A s discusse d in detai l earlier , manufacturer s have man y option s availabl e in the design o f a n onboard systemwhic hcan manag e or eliminat e an yperceive d increas e in 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 , or breakawayrollove r valve s coul d be used . Th e integrit yo f the critica l portio n o f vapo r line betwee n th e fue l tan k an d rollove r valv e coul d be assure d throug hthe us e o f stee l brai d covere d rubbe r hos e in ke yarea s or stee l tubing.[28 ] Bot hrubbe r an d stee l vapo r line hav e been use d o n pas t vehicl e models . I f chafing o f thi s critica l portion o f vapo r line i s a concern , the affecte d area s coul d be wrappe d i n a spira l sprin g fo r protection . Also , slac k coul d be provide d in thi s critica l portio n o f vapo r line t o minimiz e the possibilit yo f separatio n o r ruptur e in a n accident . Improved o r additiona l fittings , adhesives , o r clamp s coul d be used t o increas e the strengt ho f ke yvapo r line connection s betwee n the fue l tan k an d the rollove r valve . Concern s relate d t o th e charcoa l caniste r can be addresse d b yusin g a reinforce d caniste r shel l or a protectiv e barrier . Whil e thes e maybe somewha t extraordinary , thi s brie f listin g demonstrate s tha t furthe r design option s ar e availabl e whic hi f used 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 a n onboard systema s saf e a s the ydeem appropriate . Onboar d system s presen t no safet yconcern s whic h canno t be eliminate d throughprope r design , an d eac h manufacture r wil l develop the fue l systemdesign whic h represent s the bes t balanc e for eac hparticula r vehicl e model , wit hful l consideratio n o f the safet yrisk s an d al l othe r key 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 , the 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 the potentia l fue l system improvement s tha t coul d resul t fro mthi s reexaminatio n includ e a n acceleratio n o f the transitio n fro mrear fil l t o sid e fill , integratio n o f the curren t externa l vapo r ven t line insid e the fillpipe , bette r placemen t o f the fue l tank , or eve n improvemen t i n th e fue l tan k integrit yitself . Also , an ynumbe r o f othe r mino r modification s or improvement s in the fue l o r emissio n contro l system s coul d be mad e whic hcoul d enhanc e safetyan

d performanc e an

d perhap s reduc e cost . Thes e includ e area s suc ha 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 .P.5 3

-52

- Also , i t i s likel ytha t an onboar d refuelin g contro l requiremen t woul d lea d t o a decreas e i n th e amoun t o f fue l spille d in-us e an

d thu s improv e th e overal l safet yo f refuelin g events . I n th e certificatio n refuelin g test , vehicle s woul d hav e t o b e designe d t o accommodat e a refuelin g dispensin g rat e a t th e hig hend o f th e presen t rang e o f in-us e value s (8-1 0 gallon s pe r minute ) withou t an yspillag e o r spitbacks . Thi s i s becaus e an

yfue l spille d durin g 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 anyspillag e tha t occurre d durin g 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 syste m fillpip e design s ar e capabl e o f handlin g dispense d fue l a t flo w rate s up t o 1 0 gallons/minut e withou t allowin g anyspitback . 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 som e curren t vehicl e fillpip e design s whic hhav e difficult yacceptin g fue l a t th e lowe r end 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 th e long term , EP Ai s considerin g an in-us e dispensin g rat e limi t o f 1 0 gallon s pe r minut e alon g wit hanyonboar d requirement . Also , fro mth e analysi s presente d above , i t i s eviden t tha t implementin g 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 , addin g a rollove r protectio n devic e wil l improv e th e safet yo f presen t fue l tan k system s whic hus e a 1/2 " externa l ven t lin e withou t rollove r protection . Second , addin g a rollove r valv e wil l enhanc e th e safet yfo r thos e vehicle s whic hno wus e a limitin g 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 hprovide d b yth e limitin g orifice . Las t o f all , i t shoul d b e note d tha t refuelin g 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 refuelin g vapor s t o ignit e inadvertentl ya s the yescap e fro mth e fillnec k opening . However , a s onboar d control s ar e phase d in , and mor e and mor e vehicle s rout e refuelin g vapor s awa yfro mth e fue l pum p operato r t o a safe r poin t (th e charcoa l canister ) th e overal l ris k involve d i n refuelin g a vehicl e wil l b e reduced . Finally , t o addres s anyspecia l concern s regardin g onboar d syste mcrashworthines s and t o perhap s improv e crashworthines s ove r curren t vehicles , ther e i s a n alternativ e onboar d syste m desig n availabl e whic hmanufacturer s ma yelect . A s i s show n i n Figur e 18 , thi s syste mi 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 to p o f th e fue l tank , instea d o f externally .. PRESSUT^AACULM ' RELIEFCA

P Figur e 1 8 ALTERNATIVE INTEGRATE D EVAPORATIVE/REFUELIN GSYSTE M TAN K MOUNTE D VALVE S REA R MOUNTE D CANISTE R J-TUB E SEAL

MECHANICAL O R SOLENOI D ACTUATE D VENT/ROLLOVE R VALVE , LIMITIN

GORIFIC E & LIQUID/VAPOR SEPARATOR

5/8 " DIA . 3 ' LONG

/ . ^-J-TUB E SEAL CONTROLLE D LEA

K PURG E VALVE

3/8 " DIA . 5 ' LONG 

# ^/—iXH-/ - l e n c o I

T O PURG E INDUCTIO

N POIN T

~ 3 LITE R CANISTE R

1 4 GALLONFUE L TAN

K

### -54

-

Asolenoi d activate d rollove r valv e coul d be used (Figur e 19 ) whic hi s locate d o n to p o f o r insid e the fue l tank . [29 ] Thi s valve woul d normall ybe close d excep t during refuelin g when i t woul d normall ybe close d excep t during refuelin g whe n i t woul d be electronicall yopene d b ya switc hlocated near th e openin g o f the fillpipe . Th e switc hcoul d be activate d eithe r b yth e opening o f the doo r ove r the fue l ca p o r remova l o f the 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 , i n 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 the vent line . On e variatio n on thi s design (se e Figur e 21 ) woul d be simpl e mechanica l bal l valv e buil t in combinatio n wit hothe r needed valves.[15 ] A s i s show

n in Figur e 18 , thi s onboard systemdesign ma y need a fil l limite r t o allowfor norma l refueling operation s (i.e. , automati c shut-off ) an d t o preven t overfilling the tan k durin g ful l refills . Asampl e design i s show n in Figur e 22 . [29 ] Th e operatio n o f the fil l limite r i s quit e simple . Whe n the tan

k i s ful l the floa t rise s in the fil l limite r an d close s of f the refueling ven t line . Thi s cause s pressur e t o ris e in the tank , subsequentl yfue l run s u p the fillpip e an d activate s the 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 fro ma n engineering perspective , the 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 the en

d o f a ful l refill . Froma safet yperspectiv e thi s alternativ e i s attractiv e becaus e al l the 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 line (Figur e 1 ) can be eliminate d an d the othe r systemvalve s an d vapo r line s ar e move' 1 

### , awa yfro mthe vehicl e shel l t o a mor e protecte d are a withi n the vehicl e body . Also , no vapo r line exist s betwee n the fue l tank an d th e rollove r valve , s o vapo r line integrit yan

d connection s ar e les s critical . Finally , depending o n howhigha 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 design coul d be use d t o mee t the onboard requirement . Bladde r tank s coul d lea d t o a substantia l improvemen t i n fue l systemsafet yb yproviding a

n additiona l shel l o f protectio n t o hel p reduc e fue l spillag e in cas e o f a n 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 be 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 sFigur e1 9



### CA? ACTIVATOR 

## Z

## H ( ^ H SOL-BNOI D VAUVI 3

.050 " BYPAS S

BALL-lM-£A6, £ fL-OAT " vALV e i c n c n I



### KJ O 5CAL g

SCHEMATI C O F POTENTIA L ONBOAR D VAPO R RECOVER Y SYSTE M



# K J AMUELLE R ASSOCIATES . INC . H O I • . CDOCWOO D tTRCf T •AtTIMOllC.MAaVt.AM D 2.il l JANUAR YSI . !•• •Figur e20

p 6|A 5 CA P



# 1 

# £ i -^A S CA P OOOfZ

Mc9KieKJ"TAR YSWITC H £LA S CAP

A6T 

### IVAT^I ^



## uevef c (f>W»KJ6 « UPWAR D JC ? ALLO W ReriOVALOf

CAP ) i c n cr\ I

,. ( m:NTIA

L MOMKNTAM

V SWITC HLOCATION S



### M O SCAL E 

# lAf i MUELLE R ASSOCIATES . INC . H O I a . cooewoo o STUCC T
•ALTIMONC . MARVLAN O 2 HI T JANUAR Y91 . !•• «P.5 8

-57 -

Figur e 2 1 

### COMBINATIO N VALV E

•^o.o.* 1

.4 - 1.0 .

ROLLOVE RSHUTOFF 1/2 ' OI A S S BALL .7/8 " t.O . SCREE N 1 1/ 8 •OVERFIL L SHUTOF F

A*A*A T ATA v ATK v A"*Zvra v VAT£VA T A*ArA*A* A »»VA*A*A*ATATA*A**TAT»TATA*A'»A'»AT»TA» r »T . A»A»A»A^A'»A*A»AT4TATA'»ATATATATA*A*A'CA»A : r 4 yA T t .r A wA WjCW

A ^ A wA T^t

L w^r A TtK.TtyA rt

k r A jt k r.

*A*A*A*A*A*A*A»AT»TA'»A'»A*ATAVA'rA*A*ATAT

A»A»A»A'»ATA»A'»A*A'»A*A*A»A*A»A*ATATA»A''A '

*A*A*An.TATA»A*ATA*A*A*A , *AnTA'VA'»A'»A Y

TA»A»A»A»ATATA'AnrA , 'ATATAVA'»A , »ATA»AVA T S. S MES H

^&A W &&&^&J&&&&iF&9&4&&&&m\\ VAPORLIQUI D SEPARATO RFigur e2 2



### fUU- L fAKl K 

## */& " PASSA T

0.050 " BYPAS S

i U i 0 0 I

liALL-IN-CAG E FLOA T VALV E 

### M O scAu e 

# K B MUELLE R ASSOCIATES . WC . 140 1 • . COOIWOO O CTReC T RALTIMORC . MAftVLAM D tltt f JANUAR YRl . !•• •P.6 0

-59

- canister , externa l plumbing , o r 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 evaporativ e syste mand 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 highcost s o r packagin g problem s wit hcanister-base d onboar d systems . EP Ai s quit e intereste d i n collapsibl e bladde r tank s a s an optio n t o canister-base d onboar d systems , an d plan s t o furthe r explor e th e cos t and technologica l feasibilit yo f thi s approac ha s wel l a s th e safet yand emissio n benefits . I n conclusion , th e informatio n and rational e presente d abov e refut e th e assertio n tha t addin g a n onboar d syste mwoul d directionall yincreas e in-us e risk , eve n i f onl yb ysom e unquantifiabl e (presumabl ysmall ) amount . An yperceive d ris k i s manageable , and furthermore , i t appear s tha t th e ne t effec t o f a n onboar d refuelin g contro l requiremen t coul d b e a potentia l increas e i n fue l syste msafety . A s discusse d above , and i n Sectio n IV 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 .P.6 1

-60

- VI . Cos t an

d Leadtim e Consideration s Th e comment s receive d regardin g onboar d vapo r recover y system s als o addresse d th e cos t and leadtim e implication s o f implementin g suc hcontrols . Mor e specifically , severa l o f th e comment s addresse d onboar d safet ycost s i n som e for m(usuall y addressin g hardwar e costs) , and severa l commenter s expresse d som e concer n ove r EPA' s leadtim e estimate . A n analysi s o f th e cost s an

d leadtim e necessar yt 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 ke yconsideration s whic hi s ofte n balance d carefull yagains t safet yconcerns , and th e cost s neede d t o implemen t onboar d system s safel ymus t b e reasonabl e relativ e t o othe r safet ycost s and 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 leadtim e 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 , and addres s al l safet yconcern s and t o compl ywit hth e tes t requirement s prescribe d i n FMVS S 301 . Th e firs t portio n o f thi s sectio n addresse s onboar d safet y costs ; th e secon d discusse s leadtim e and describe s th e basi s fo r EPA' s leadtim e estimate . Som e 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 EP Aanalysi 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 i n Sectio n IV , th e cost s neede d t o implemen t onboar d control s safel yfal l i n severa l areas . R& D typ e cost s wil l b e incurred , som e ne wo r modifie d component s wil l b e neede d whic hma yslightl yaffec t vehicl e operatin g costs , and safet ycertificatio n testin g wil l b e necessary . Howeve r befor e beginnin g 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 and EPA' s evaporativ e emissio n contro l requirement s impac t onboar d safet ycosts . Th e contro l o f refuelin g emission s throug ha n onboar d syste mwoul d no t b e th e firs t Federa l regulatio n t o requir e a n investmen t t o improv e fue l syste msafety . Th e firs t fue l syste mintegrit ystandard s (FMVS S 301 ) wer e implemente d b y NHTS Afo r 196 8 vehicles , and 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 le d t o a n improvemen t i n fue l syste msafet 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 exten d th e coverag e o f impac t type s t o includ e rollove r event s and , rea r en d and sid e collisions . A198 3P.6 2

-61

- NHTS ATechnica l Report[19 ] describe s th e natur e o f th e modification s mad e i n respons e t o th e upgradin g 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 standar d and provid e a highe r leve l o f in-us e assurance . 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 i n 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 recontourin g 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(an 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 tw o cost s ar e added , NHTS Aestimate d th e tota l safet y cos t resultin g fro m th 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) . Base d o n an evaluatio n o f in-us e acciden t informatio n fo r 197 7 and late r mode l yea r vehicles , NHTSA' s 198 3 Technica l Repor t als o estimate d tha t th e upgradin g o f FMVS S 30 1 woul d i n th e long ter m

annuall 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 yimprovin g man yaspect s o f overal l fue l syste msafet yand 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 i n Sectio n II I o f th e report , an onboar d syste m

i s i n man yway s a n extrapolatio n o f curren t evaporativ e emissio n contro l technolog yand th e tw o system s ar e quit e similar . Man yo f th e contro l technique s and basi c syste m component s use d woul d b e similar , and th e sam e syste mand vehicl e assembl yapproache s coul d b e used . I n fact , man y manufacturer s wil l likel yintegrat e thei r refuelin g and 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

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 and cost s t o mee t th e 197 6 revisio n t o th e standar d (adde d rollove r test ) cos t $2.10.[30,31 ]P.6 3

-62

- Tabl e 3 Summar yo f Vehicl e Modification s i n Respons e t o 301-7 7 Vehicl e Component s Fue l Syste m Component s Fue l Tan 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 Improv e Crashworthines s

- Increas e gaug e o f tan k materia l

- Ad d 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 seam s

- Strengthe n mountin g b yaddin g brackets , revisin g mountin g bolts , increasin g torqu e o f mountin g strap s

- Strengthe n fille r ca p seal , improv e 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 Syste mIntegrit y Rea r Floo r Pan/Suppor t Rails/Whee l Housin g Rea r Suspensio n (Springs , Shoc k Absorbers )

Rea r Axl e Assembl y

Rea r Axl e Assembl y Sea t Bel t Bracket s Engin e Moun t Powe r Steerin g Pum p Bracke t - Revise , ad d support s

- Chang e suppor t brackets , revis e mountin g bolts , revis e mountin g procedure , and 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 4



### -63

- designed t o mee t the 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 hig hleve l o f in-us e safet y performance , i t follow s tha t a thoroug hevaluatio n o f the potentia l safet yimplication s o f evaporativ e contro l system s ha s alread

ybee n conducted . Sinc e onboard systems ar e basicall yextension s o f evaporativ e emissio n systems , clearl y man yo f the safet ydesign consideration s associate d wit h onboard system s relate d t o passing FMVS S 30 1 or providing in-us e assuranc e hav e alread ybee n resolve d or at leas t addressed in evaporativ e emissio n systemdesigns . Consequently , muc ho f the "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 keep the magnitud e o f the onboard safetydesign proces s in perspective , becaus e clearl ymuc ho f the safet y technolog

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

yexists . Remembering the relativel yinexpensiv e an d ye t effectiv e natur e o f curren t fue l systemintegrit ymeasure s an d the "incremental " natur e o f onboard safet yin terms o f the magnitud e o f the tas k an d actua l cos t relative t o evaporativ e systems , i t i s nowpossibl e t o describ e the component s whic h facto r int o onboar d safet ycosts . Basically , the integratio n o f safet yint o a fue l systemincorporating a n onboard control s involve s four type s o f costs . Thes e fou r 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 howeac ho f the cos t component s ar e affecte d b yonboard safety . T o begi n with , some researc han d developmen t wil l have t o be performe d t o safel yintegrat e onboar d control s int o vehicl e fue l systems . EPAha s estimate d tha t the 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 in the rang e o f $0.3 5 t o $0.5 5 pe r vehicl e (passenge r ca r an d ligh t truck ) . Thi s cos t i s fo r an ydevelopmen t effor t involve d in combining the component s o f a n onboar d system

wit hthe 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 yin the design an

d developmen t proces s an d ye t i s onl yon e par t o f the tota l effort , onl ya fractio n o f the tota l cos t shoul d be directl yallocate d t o safety . Also , becaus e muc ho f the 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 ybe a smal l fractio n o f the tota l cos t in thi s area . I n addition , becaus e o f the incrementa l natur e o f the onboard system , muc ho f the researc han d developmen t tha t wen t int o making evaporativ e contro l system s saf e can be applie d directl yt o onboar d controls .P.6 5

-64

- Give n tha t manufacturer s ar e designin g an onboar d syste m i n th e contex t o f manyrequirement s and certai n desig n feature s serv e multipl e functions , i t i s ver ydifficul 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 onboar d safet ycost s relate s t o specifi c hardwar e tha t ma yb e require d t o insur e fue l syste m safety . EP Aha s estimate d cost s fo r thre e specifi c item s 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 syste mdesig n explicitl yfo r safet y reasons . Thes e thre e item s ar e 1 ) a rollove r valve , 2 ) a pressur e relie f mechanism , and 3 ) fue l system \ modification s necessar yt 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 and 20 ) t o b e $4.60 . [17 ] Thi s pric e include d th e cos t o f th e valve , a n actuato r locate d a t th e fillcap , and th e necessar ywirin g and 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 , and 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 an appropriat e rollove r valv e cos t fall s int o a rang e o f $3.0 0 t o $6.00 . 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 incorporatin g a mechanica l fillnec k seal , and 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 , EP Aha s estimate d tha t thi s devic e woul d increas e syste mcost 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 hperfor mth e sam e basi c functio n and ar e simila r i n complexity.[32 ] Th e fina l onboar d safet yhardwar e cos t account s fo r any fue l syste mmodification s tha t woul d b e necessar yi n orde r t o safel yaccommodat e anyonboar d contro l hardware . Fo r example , a vehicle' s 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 , fo r safet y reasons , som e sligh t re-routin g o f th e fue l system' s vapo rP.6 6

-65

- line s ma yb e required . EP Aha s estimate d a tota l 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 anymodifications , 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 . Summin g u

p 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 marku p facto r valu e o f 1.2 6 appear s representative.[33 ] 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 thir d componen t o f safet ycost s account s fo r any safet ycras htestin g tha t woul d b e necessary . EP Aha s estimate d th e cos t o f cras htestin g t o assur e fue l syste m integrit 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.[34 ] Thi s estimat e i s base d o n fou r test s require d pe r bodyline/styl e wit htw o vehicle s require d fo r eac hsequenc e o f fou r tests . Clearl y safet ycras htes t cost s ar e ver yminima l i n th e long ter mand d o no t pos e an obstacl e t o th e adoptio n o f onboar d controls . 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 tha n on e percent . 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 resultin g 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 and pressur e relie f mechanis mi s ver ysmal l (0. 4 lbs) , and EP Aestimate s tha t onl yabou t $0.: 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 ysummin g 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 , dependin g o n th e typ e o f rollove r valv e used .P.6 7

-66

- 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 yan onboar d requiremen t t o furthe r reduc e in-us e ris k beyon d 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 o r 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 . EP Aestimate 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 som e 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 syste m

safety . Man yo f th e potentia l problem s relate d t o implementin g onboar d system s safel yhav e alread ybee n considere d i n th e desig n and developmen t o f presen t evaporativ e systems . Th e manufacturer s previou s experienc e i n implementin g evaporativ e system s safel yand th e incrementa l natur e o f onboar d system s reduce s cost s and th e leve l o f potentia l problems . Thi s analysi s demonstrate s tha t hig hlevel s o f in-us e fue l syste msafet yca n b e achieve d a t lo wcost , and ther e i s n o nee d fo r a manufacture r t o "cu t corners " o n onboar d safety . B . Leadtim e I f EP Awer e t o implemen t an onboar d requirement , i t woul d b e necessar yt o allo wa sufficien t perio d o f leadtim e betwee n th e dat e th e rul e i s promulgate d and 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 leadtim e 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 throug hsyste mdesign , development , testing , tooling , certification , and 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 som e task s canno t begi n befor e other s ar e complete . Whil e EP Aestimate s tha t non e o f th e individua l leadtim e task s requir e mor e tha n twelv e month s t o complete , du e t o th e sequentia l natur e o f som e o f th e tasks , a perio d o f approximatel y2 4 month s wil l b e th e tota l amoun t o f leadtim e require d b ymanufacturers . Figur e 2 3 show s ho wth e individua l leadtim e component s resul t i n a tota l estimat e o f 2 4 months . First , fou r t o si x month s ar e include d fo r manufacturer s t o develo p and optimiz e workin g 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 workin g prototype s alread yexis t and man ymanufacturer s hav e evaluate d thes e o r thei r ow n prototyp e t o som e degree . Onc e th e prototyp e developmen t i s complete , initia l durabilit y testin g o f th e prototyp e coul d b e conducte d unde r laborator y conditions . Thi s laborator ytestin g i s no t expecte d t o las t mor e tha n tw o months .

# Safety-u p to 1 4 HO . Tooling : N» u10-1 2no . Mit. (- 8 no , COT , 3- 4 m . IIIIIIIIMIIIIIIHI I IHIIIM I i iiiiiiiiiiiiiiiiiii i iiiiiiiiiiiiiiiini i IMllMllllMMIMi l Mlltllllllltllllll l llllllllllllllltlll l 

# Certificatio n18-1 2HO

.

FR M " * IIIIIIIIIIIIIIIIIII I

J I L iiHMimimiiii M IIIIHIIIIIIIIIIH ' llllllllllllllllll l lllllllllllllllllll l lllllllllllllllllll l lllllllllllllllllll l lllllllllllllllllll l llllllllll l

•(IIIIIIII I

llllllllllllllllll l llllllllllllllllll l llllltlHIIIIlltll l llllllllllilllllll l 

# DevelopMent !

Prototyp eHNO . La b 2 HD. 

## iHeMcl e4- 6 RO. J L— | I I L i i i 

# 4 8 

# 1 2

Honth s 1 6 2 8 IIIIMIIIIII1IIIIII I lllllllllllllllllll l lllllllllllllllllll l

J I 

# 2 4 i l



# = Dtnota ttclnlulinf lfltxililit y 

# FIGUR E2 3 ONBOAR

DLEADTIM E

o oP.6 9



### -68

- Following laborator ytesting , thre e separat e action s can begi n simultaneously . Thes e thre e task s ar e 1 ) in-vehicl e testing , 2 ) tooling , an d 3 ) safet yoptimizatio n an d prov e ou t o f th e overal l contro l systemthroug hefficienc yan

d durabilit y verification . Simila r in-vehicl e testing program s have required fou

r t o si xmonth s for completion . Tooling coul d als o begi n onc e laborator ytestin

g i s complete . Figur e 2 3 show s EPA' s estimat e tha t toolin g coul d requir e a s littl e a s thre e month s an

d a s muc ha s 1 2 month s depending on the magnitud e o f th e task . However , eve n i f 1 2 month s ar e require d fo r tooling or toolin

g decision s ar e delayed , thi s tas k woul d stil l be complet e wel l withi n the tota l 24-mont hleadtime period . Safetyevaluatio n i s the third tas k whic hcoul d begi n subsequen t t o the completio n o f the prototyp e laboratory testing . Safet yevaluatio 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 per bod

yline/style ) t o verif ythe 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 the completio n o f laboratorytesting , a ful l 1 4 month s o f leadtime woul d be availabl e t o manufacturer s i f neede d t o perfor mthi s task . Base d o n a discussio n wit h NHTSA , i t appear s thi s amoun t o f tim e woul d be mor e than adequat e t o perfor

m the necessarysafet yevaluation.[35 ] Th e onl yothe r proces s whic hrequire s completio n withi n th e 24-mont hleadtim e 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.[36 ] Thi s estimat e i s base d on 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 the completio n o f in-vehicl e testing , EP Aestimate s a tota l leadtime perio d o f 2 4 month s wil l be neede d overall . Twenty-fou r month s o f leadtime i s quit e reasonable , especiall ysinc e mos t o f the 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 the system' s performanc e hav e alread ybee n teste d an

d prove n t o be 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 no nee d t o design an d develop entirel ynewsystems . A s a matte r o f fact , man yo f the critica l onboard design issue s have alread ybee n incorporate d int o curren t fue l systemdesign s wit hthe 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 the 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 be no mor e o f a problemt o vehicl e manufacturer s tha n wa s implementing evaporativ e emissio n contro l systems .P.7 0


### -69

- EPA' s 24-mont hleadtim e 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 standard whic hwa s implemented wit hjus t 1 2 month s o f leadtime , the 198 1 2. 0 g/tes t LDV/LD T evaporativ e emissio n standard whic hwa s implemented wit h2 4 month s o f leadtime , an d the 198 5 HDG

V evaporative standard 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 faced leadtime factor s identica l t o the one s tha t woul d accompan

ya n onboard requirement , including safety . Sinc e manufacturer s wer e abl e t o safel yan d effectivel yintegrat e evaporative 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 the magnitud e o f th e onboard implementatio n tas k i s similar , manufacturer s shoul d als o be abl e t o safel yan d effectivel yintegrat e onboard 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 ythe pas t experienc e o f NHTSAi n implementing the variou s version s o f FMVS S 301 . Tabl e 4 show s the 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 the standard wa s revise d fo r 197 6 mode l yea r passenge r cars , seventee n 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 hthe mos t substantia l upgrad e t o the 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 new requirements . Also , beginning in the 197 7 mode l year , FMVS S 30 1 wa s extende d t o includ e light 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 (witha GVW R greate r than 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 the informatio n provide d above , 2 4 month s i s adequat e time t o implemen t onboar d controls , wit hful l consideratio n o f al l safet yconcerns . Becaus e safet y evaluatio n can procee d i n paralle l t o thre e othe r tasks , mor e tha n a yea r i s availabl e fo r compute r simulatio n an d actua l safetycras 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 expand safet ytechnolog yuse d in curren t evaporativ e emissio n contro l system s t o develo p effectiv e onboar d systems . Also , muc ho f the safet y-70

- P.7 1

Tabl e 4 Chronolog

yo f FMVS S 30 1 Requirement s 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 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 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 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

7 2/ 3 yrs . 1 2 mos .

1 2 mos .

1 2 mos .

[1 ] Moto r Vehicl e SafetyStandard 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 yStandard No . 301 , Fue l System Integrity , 3 9 F

R 10588 , Marc h21 , 1974 . [3 ] Federa l Moto r Vehicl e Safet yStandard No . 301 , Fue l Syste m Integrity , 4 0 F

R 48352 , Octobe r 1 5 1975 .P.7 2

-71

- developmeh t whic hwoul d b e require d ha s alreadytake n plac e wit hth e identificatio n and resolutio n o f suc hpotentia l safet y issue s a s rollove r protectio n and fue l tan k pressur e relief . Consequently , a 24-mont hleadtim e perio d woul d provid e manufacturer s wit hsufficien t opportunit yt o develo p saf e and effectiv e onboar d systems . Whil e thi s analysi s indicate s tha t th e curren t leadtim e estimat e o f 2 4 month s i s reasonabl e fo r virtuall yal l vehicl e models , EP Ai s sensitiv e t o manufacturer s concern s regardin g leadtim e requirements . Publi c comment s regardin g EPA' s 24-mont hleadtim e estimat e wer e submitte d a s par t o f comment s o n EPA' s origina l Gasolin e Marketin g Study(Jul y1984).[37 ] Whil e mos t commenter s di d no t objec t t o th e 24-mont hleadtim e estimat e presente d i n th e Gasolin e Marketin g Study , aut o manufacturer s fel t tha t a 24-mont hleadtim e wa s insufficien t t o implemen t onboar d controls . Th e leadtim e period s suggeste d by thes e commenter s range d fro mthre e t o si xyears . Thos e commenter s suggestin g tha t fou r o r mor e year s woul d b e necessar yals 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 redesig n and turnove r occurs . Usin g thi s approach , implementin g onboar d control s woul d b e les s burdensom e and woul d allo wextr a tim e t o dea l wit himplementatio n o r packagin g problem s o n uniqu e vehicles . However , i t i s wort hnotin g tha t comment s receive d fro mth e manufacturer s suggestin g th e nee d fo r a longe r leadtim e wer e no t supporte d wit hanycompellin g argument s whic h woul d substantiat e th e insufficienc yo f a 24-mont hleadtime . EP Ai s committe d t o providin g manufacturer s th e leadtim e necessar yt o implemen t onboar d control s safel yand effectively . Consequently , EP Ai s ope n t o considerin g a two
o r perhap s three-mode l yea r 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 tim e t o solv e anyonboar d syste mpackagin g and testin g problem s fo r uniqu e vehicl e models . Also , i f a manufacture r ha d uniqu e safet yconcern s o n on e o r tw o body lines/styles , thi s approac hwoul d offe r a manufacture r mor e leadtim e t o properl yaddres s them . I n addition , i t coul d improv e th e cos t efficienc yo f control s b yallowin g 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 bein g planne d and thos e no w i n production . 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 tha n 24-month s leadtim e 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 rul e i s muc hbeyon d tha t period ,P.7 3



### -72

- the manufacturer s woul d have the remainde r o f tha t mode l yea r in additio n t o the 2 4 month s discusse d previously . Therefore , in actualit ymanufacturer s coul d have 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 . In conclusion , give n th e magnitud e o f the 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 the variou s version s o f FMVS S 301 . However , EP Ai s committe d t o providing the leadtime necessaryt o implemen t onboard control s bot hsafel yan d effectively . Thu s EP Ai s ope n t o considering a shor t phase-i n perio d o r othe r approache s whic har e pertinent . U p t o thi s point , thi s repor t ha s addresse d onboard safet y issue s fro

m primaril ya passenge r ca r an d light truc k poin t o f view . I t shoul d be 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 fueled vehicle s (HDGVs) , onboard contro l technolog ycoul d als o be applie d t o HDGVs . Whil e man yo f the safet yissue s discusse d thu s far woul d be identica l in a n HDG V application , some aspect s o f HDG

V onboard safetywoul d be distinc t fro m light-dut yissues . Th e nex t sectio n in thi s repor t ha s bee n included t o addres s the similaritie s an d difference s betwee n heavy-dut yan

d light-dut yonboard safet yissues .P.7 4

-73

- VII . Heavy-Dut yGasolin e Vehicl e Requirement s Sinc e a n EP Aonboar d refuelin g 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 and ligh t trucks , i t i s importan t t o evaluat e an ypotentia l HDG

V onboar d syste msafet yconsideration s a s wel l a s thos e encountere d i n light-dut yapplications . Whil e non e o f th e comment s receive d regardin g th e safet yimplication s o f onboar d specificall yaddresse d HDGVs , overal l light-dut y concern 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 syste mconfiguration s diffe r somewha t fro mthos e foun d o n passenge r car s and ligh t trucks , and th e fue l syste msafet yrequirement s als o differ . Thi s sectio n o f th e repor t identifie s distinc t HDGV onboar d safet yissue s and discusse s th e implication s thes e distinction s coul d hav e o n manufacturer s fue l syste msafet y designs . I t begin s wit ha brie f descriptio n o f som e o f th e mor e commo n HDG

V configurations . Followin g thes e descriptions , a discussio n o f th e HDG V fue l syste msafet ystandard s wil l b e presented , and difference s betwee n light

- and heavy-dut y vehicl e onboar d system s du e t o fue l syste mconfiguration s and safet ytes t requirement s wil l b e discussed . Next , HDGV onboar d safet yissue s wil l b e introduce d and analyzed . Finally , thi s sectio n wil l end wit ha brie f segmen t concernin g th e effec t o f HDG V onboar d safet yo n cost s and leadtime . Befor e beginnin g 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 ratin g (GVWR ) o f 10,00 0 lb s 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 EP A classifie s al l gasoline-powere d vehicle s wit ha GVW R o f 8,50 1 lb s o r mor e a s HDGVs . Ou t o f EPA' s HDGV categor yonl y90,00 0 vehicle s (o r approximatel y25% ) hav e a GVWR greate r tha n 10,00 0 lbs . Thu s mos t (o r approximatel y75% ) o f EPA' s HDGV clas s (thos e vehicle s wit ha GVW R betwee n 8,50 1 and 10,00 0 lbs-Clas s lib ) i s covere d byth e LD T 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 yidentica l t o thos e o n lighte r weigh t LDTs , and 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 GVW R exceed s 10,00 0 lbs . A . HDGV

Fue l Syste mConfiguration s Jus t a s ther e ar e chassi s and drivetrai n difference s betwee n heavyand light-dut yvehicles , ther e ar e als o som e difference s i n thei r fue l syste mconfigurations . Fue l tank s ar e generall yo f a heavie r constructio n and ar e large r i nP.7 5

-74

- volume ; dua l fue l tank s ar e als o mor e common . Fue l tan k shape s var ysomewha 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 ver ylimite 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 th e fuel/vapo r handlin g system s o f HDGV s ove r 10,00 0 lb s GVWR . [38 ] Th e ke yresult 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 . First , a s ca n b e see n i n Tabl e 5 , ther e ar e onl ytw o manufacturer s whic hmarke t HDGVs . Betwee n the mthe yoffe r onl y abou t 1 0 differen t chassi s model s t o whic hanynumbe r o f differen t bodie s o r payload s ca n 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 , ste p rectangular , and 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 fro m2 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 fo r singl e tan k HDGV s and 7 5 gallon s fo r dual-tan k HDGVs . EP Aestimate 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 bein g i n heavie r weigh t truck s (>20,00 0 lb s GVWR).[17 ] Mos t passenge r ca r and ligh t truc k fue l tank s ar e locate d unde r th e vehicl e bodyand thi s i s als o th e cas e fo r som e HDGV configuration s (e.g. , schoo l buses) . However , o n som e HDGV 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 fram e (righ t o r lef t han d sid e fo r singl e tanks , bot hside s fo r dua l tanks ) and ar e expose d t o th e roa d rathe r tha n shielde d b yth e vehicl e body . A s wa s allude d t o above , mos t HDGV tank s hav e onl ya limite d fillpip e lengt h(<8" ) and som e hav e essentiall ynon e a t all , wit hth e fue l ca p bein g integra l t o th e tank . Finally , wit hregar d t o th e HDGV evaporativ e emissio n system s tw o observation s ar e important . (Se e Figur e 2 5 fo r a n exampl e o f a HDGV evaporativ e system. ) First , fo r th e sam e reason s a s describe d fo r passenge r car s and ligh t trucks , HDGV s us e a limitin g 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 a n HDGV i s mor e tha n twic e th e averag e o n passenge r car s and LDT s (2.8-4. 0 liters) . However , o n HDGV s diurna l emission s fro mth e fue l tan k and ho t soa k emission s fro mth e fue l meterin g syste m ar e route d t o differen t canisters . Ho t soa k emission s ar e somewha t mor e o f a concer n o n HDGV s becaus e mos t ar e carburete d rathe r tha n fue l injected . T o th e degre e tha t HDGV engine sSelecte d Characteristic s o f Heavy-Dut y

Manufacture r GM

FORD Mode l o r

Serie s P4T04 2
P6T04 2
C5D04 2

C6D04 2 C7D04 2 C7D06 4

B6P04 2

F-Serie s B-Serie s C-Serie s Fue l Tank

Rectangula r Rectangula r Rectangula r Rectangula r

Rectangula r Rectangula r

Rectangula r

Rectangula r Rectangula r D-Typ e Shap e

and Step

an d Step Tabl e 5

Gasolin e Vehicl e Fuel/Vapo r

Fue l Tan k Locatio n 3 0 gal . Moun t O n Righ t Hand Frame 3 0 and 6 0 gal . Mounte d o n Lef t Hand Frame 2 0 gal . Mounte d Righ t Hand Frame 5 0 gal . Ste p Mounte d Righ t o r Lef t Han

d Frame 2 0 gal . Mounte d Righ t Hand Frame 5 0 gal . Ste p Mounte d Righ t o r Lef t Han

d Frame Dua l 5 0 gal . Step Mounte d Lef t and Righ t Hand Frame 3 0 gal . Mounte d Righ t Hand Frame 6 0 gal . Mounte d Righ t Hand Frame 3 5 gal . Righ t Han

d Sid e Frame Mounte d 3 0 gal . Righ t Han

d Sid e Frame Mounte d 5 0 gal . Righ t Han

d Sid e Frame Mounte d Handl j .n q

Numbe r o f Canister s 2
2
2

2

2

2

2

2 System s b

y Vehic l

Siz e o f Canister s 150 0 and 250 0 c c 150 0 and 250 0 c c 150 0 and 250 0 c c

150 0 an d 250 0 c c

150 0 and 250 0 c c

140 0 ml . 140 0 ml . 140 0 ml . ea .

ea .

ea . <

s Model/Serie s Diamete r o f Ven t Line s 0.31 2 in . 0.31 2 in . 0.31 2 in .

0.31 2 in .

0.31 2 in .

3/ 8 in . 3/ 8 in . 3/ 8 in . Diamete r

o f Purg e Line s 0.37 5 in . 0.37 5 in . 0.37 5 in .

0.37 5 in .

- j

U l

0.37 5 in .

3/ 8 in . 3/ 8 in . 3/ 8 in .P.7 7

-76

- Figur e 2 4

HDG V Fue l Tank s

D-Shap e

Standard Rectangula r

Ste p Rectangula rFigur e 2 5 TYPICAL HDG

V EVAPORATIVE SYSTE M

"BALL CHEC K VALV E TAN K RESTRICTOR PRESSURE/VACUU

M RELIE F

SEALED A GA S CAP- * 

# L 3/16 " DI A -13 ' LON

G 

# IfPURG E VALV E 

# U c :€>< *

-3/8 " DI A ~ 3 ' LON

G * TO PURG E INDUCTION POIN T 2. 5 LITE R CANISTE R I I

3 0 GALLO

NFUE L TAN

K

o oP.7 9



### -78

- fue l system s ar e converte d fro mcarburete d t o fue l injecte d a s i s nowprojected , concern s ove r ho t soak emission s ma ydiminis h an d allowthe eliminatio n o f the secon d caniste r on thos e vehicles.[39,40 ] Wit hthi s brie f backgroun d on HDG

V fuel/evaporativ e system s w e turn nowt o a discussio n o f the fue l system safet y standard s whic happl yt o HDGV s ove r 10,00 0 lbs 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 systemconfiguration . Th e Departmen t o f Transportation/Burea u o f Moto r Carrie r Safet y(BMCS ) ha s requirement s whic happl yt o al l HDGV s ove r 10,00 0 lbs GVWR . I n addition , schoo l buse s mus t mee t the requirement s prescribe d specificall yi n FMVS S 301 . Th e BMC S an d FMVS S 30 1 requirement s ar e summarize d below . 1 . Bureau o f Moto r Carrie r Safet yRequirement s BMC S safet yregulation s includ e bot hspecifi c desig n requirement s an

d actua l fue l tan

k safet ytests.[41 ] Th e design requirement s contai n rule s . governing the 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 testin

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

k ha s t o be abl e t o pas s two fue l tank safet ytests . Th e firs t o f thes e tw o tests , the safet yventing systemtest , involve s applying a n enveloping flame t o a

n inverte d fue l tank t o insur e tha t the fue l tank' s safet yventing systemactivate s prio r t o the tank' s interna l pressur e exceeding fift ypound s pe r squar e inch . Th e secon d fue l tank safet ytes t i s a leakag e tes t whic hinvolve s filling the tank t o capacit yan d rotating the tan k 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 the tank no r an yfitting leak mor e than on e ounc e o f fue l pe r minut e in an ypositio n the tan k assume s during the test .P.8 0

-79

-

Figur e 2 6

Pictoria l Definitio n o f Side-Mounte d Fue l Tank . I f "th e tan k extend s t o th e lef t o f line Ao r t o th e righ t o f lin e B , the n th e tan k 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 1



### -80

- HDGVs wit hsid e mounte d fue l tank s mus t pas s tw o othe r test s whic hinvolve dropping the fue l tan k t o tes t impac t resistance . Th e firs t test , terme d the drop test , involve s droppin g a full yloaded (equivalen t weigh t o f water ) tan k fro m 3 0 fee t ont o a

n unyielding surface , s o tha t i t land s squarel y on on e corner . Asecon d simila r tes t (termed th e fillpip e test ) require s tha t a full yloaded tan k be droppe d fro

m 1 0 fee t ont o a n unyielding surface , s o tha t i t land s squarel yo n it s fillpipe . In neithe r case , ma ythe tan

k no r an

yfitting lea

k mor e than on e ounc e pe r minute . Base d o n conversation s wit hthe tw o HDG V manufacturers , the vas t majorit yo f HDG V fue l tank s ar e fram e mounte d (non-side mounted) . N o side mounte d tank s ar e offere d a s standard equipment , an d onl yon e i s offere d a s a n option.[42][43 ] Thus , thi s analysi s wil l focu s primaril yo n the safet yventing an d leakag e tes t requirement s whic happl yt o fram e mounte d tanks . However , the drop test s fo r sid e mounte d tank s wil l als o be considered . 2 . Schoo l Bu s Requirement s In additio n t o the BMC 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 includ e al l o f the tes t requirement s a s prescribe d fo r passenge r car s an

d light trucks . Schoo l buse s mus t pas s onl ya singl e moving barrie r tes t (3 0 mph ) whic hdoe s no t includ e a rollove r test . In thi s test , the barrie r impact s the schoo l bu s a t th e locatio n o f th e fue l tank , an d the fue l systemmus t be 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.[44 ] Thi s briefl ysummarize s the Federa l safet ystandard s applicabl e t o fue l system s o n HDGV s ove r 10,00 0 GVWR . Wit h thi s background informatio n w e ar e nowprepare d t o discus s how the difference s i n vehicle/fue l system configuration s an d the Federa l safet ystandard s mayaffec t the design o f a n onboar d systemfo r a

n HDG V relativ e t o the design fo r passenge r car s an d light trucks . C . Distinction s in HDG V Onboar d System s Jus t a s th e evaporativ e emissio n contro l system s used o n HDGV s ar e ver

ysimila r t o thos e use d o n passenge r car s an d ligh t trucks , i t i s als o expecte d tha t a n HDG V onboar d system woul d be verysimila r in 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 dFigur e 2 7 POSSIBL E HDG V

INTEGRATE D EVAPORATIVE/REFUELIN GSYSlfc M

• PRESSURE/VACUU M .RELIE F MECHANICA L O R SOLENOI D

ACTUATE D VENT/ROLLOVE R VALVE , LIMITIN GORIFIC E s £ LIQUID/VAPO R SEPERATO R l o o

5/8 " DI A ~13 ' LONG # 

# X '

SEALED

GA S CA P MECHANICA L -

* SEA L 

# i. PURG E VALV E 

## £X} = ^ — 3/8 " DI A

~ 3 ' LONG T O PURG E INDUCTION POINT

7. 5 LITE R CANISTE R

3 0 GALLONHDG

V FUE L TAN

K

o o

### -82

-

the requirement s levied b ythe 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 fe wke ypoint s raised previousl ywit hregard t o the magnitud e o f the tas k o f implementing onboard controls . First , lik e passenge r car s an d light trucks , al l HDGV s now 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 systemintegrit ystandard s (BMC S an d NHTSA) . Thus , a s befor e wit hthe lighte r weigh t vehicles , the applicatio n o f onboard system s i s bes t evaluate d incrementall yt o the 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 the groun d wor k ha s alread ybee n completed , the neede d modification s mad e an d component s added . I n man ycase s no change s t o presen t fue l systemsafet y assuranc e o r evaporativ e emissio n contro l measure s wil l be needed . Second , i t i s importan t t o not e tha t HDG V onboar d refueling an

d fue l tan

k evaporativ e emissio n contro l system s wil l likel ybe 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 the ynowhave separat e canister s an d contro l system s for fue l tan k an d fue l metering evaporativ e emissions . Thu s a whol e ne wsystemwil l no t be added t o contro l HDG V refuelin

g emissions ; instead the refueling an

d fue l tan

k evaporativ e emissio n contro l system s wil l be integrate d int o on e (compar e Figur e 2 5 wit hFigur e 27 ) . Thu s man

yo f the primarydesign consideration s whic h applie d fo r the evaluatio n o f onboard system s t o passenge r car s an d light truck s als o appl yt o HDGVs . Remembering the expecte d similaritie s betwee n light an d heavy-dut yvehicl e onboar d system s an d tha t the factor s affecting the implementatio n ar e als o the same , the expecte d mino r variation s in HDG V onboar d system s can nowbe discussed . Fo r sak e o f presentation , discussio n wil l begi n a t the fillpip e an d followalon

g the systemt o the canister . Th e analysi s wil l assume a

n integrate d onboar d refueling/fue l tan k evaporativ e contro l systema s discusse d above . T o begi n with , becaus e the fillpipe s o n HDG V fue l tank s ar e eithe r relativel yshor t o r integra l wit hthe 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 tank s nowus e a pressure-vacuu mrelie f valve , an

d i t i s conceivabl e manufacturer s wil l simpl ymodif y tha t valv e fo r thi s application . However , unde r the 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 the fillpip e horizontall yin the tan k a s ha s bee n demonstrate d in a prototyp e light-dut y program.[15 ]P.8 4

-83

- Asecon d potentia l differenc e lie s i n th e diamete r o f th e refuelin g vapo r lin e and relate d fue l tan k vent . Fro ma desig n perspective , th e tan k ven t and refuelin g vapo r lin e siz e (diameter ) coul d b e affecte d b yth e fue l dispensin g rate . A s par t o f th e refuelin g emission s tes t procedure , EP Ai s proposin g tha t HDGV fue l system s b e designe d fo r refuelin g a t a maximumrat e o f 1 0 gallon s pe r minute , th e sam e rat e a s prescribe d fo r othe r vehicles. * Thi s 1 0 gallo n pe r minut e dispensin g rat e result s i n an increas e i n th e curren t orific e and evaporativ e vapo r lin e diamete r fro mabou t 3/ 8 inc ht o abou t 5/ 8 inc hfo r a n HDGV onboar d system . However , t o minimiz e spillag e durin g refueling , th e BMC 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.[45 ] Fo r a n onboar d syste mthi s requiremen t coul d lea d t o a increas e i n th e diamete r o f th e tan k ven t outle t and refuelin g vapo r line . I t shoul d b e note d however , tha t whil e thi s requiremen t applie s t o al l heavy-dut yliqui d fue l tank s (bot hdiese l and 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 dispensin g rat e o f 2 0 gp mo r mor e t o reduc e th e tim e neede d t o fil l a diese l tan k sinc e thes e tank s ar e typicall ymuc hlarge r tha n gasolin e tank s and dua l diese l tank s ar e als o mor e common.[46 ] In-us e gasolin e dispensin g rate s o n th e othe r han d normall yd o no t excee d 1 0 gpm . Sinc e in-us e gasolin e dispensin g rate s usuall yd o no t excee d 1 0 gpm , and EPA' s refuelin g certificatio n tes t woul d involv e a 1 0 gp m maximu mdispensin g rate , BMCS' s requiremen t i n thi s are a ma y no t b e needed . EP Aha s discusse d thi s matte r wit hDOT/BMCS , and the yhav e expresse d a willingnes s t o conside r changin g thi s requirmen t t o appl yonl yt o diese l fue l tanks.[46 ] Nevertheless , becaus e HDGV fue l tank s d o no t us e long 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 refuelin g ven t orifice/lin e wer e size d fo r a 1 0 gallo n pe r minut e dispensin g rate , fue l coul d dispense d a t a greate r rat e withou t prematur e shutoffs . Thu s i t ma yno t b e necessar yt o siz e th e refuelin g orifice/ven t lin e t o matc hth e dispensin g rat e requirements . However , i n optimizin g syste mdesign s wit h regar d t o fue l tan k pressure , manufacturer s ma ychoos e t o us e a slightl ylarge r refuelin g ven t orific e tha n see n o n light-dut y applications .

Discussion s wit hgasolin e marketin g interest s and nozzl e manufacturer s indicat e tha t gasolin e availabl e t o passenge r cars , ligh t trucks , and HDGV s (eithe r a t retai l o r privat e pumps ) i s no t dispense d a t rate s greate r tha n 1 0 gpm .P.8 5

-84

- 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 HDGV fue l tank s i n thei r presen t configurations . On e manufacturer' s fue l tan k 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.[38 ] Also , th e nozzl e actuate d valve s shown i n Figure s 9-1 5 coul d als o b e use d o n HDGV 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 perfor m o 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 hand operatio n woul d b e th e same . Anyo f th e thre e rollove r valv e design s mentione d abov e 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 ho r othe r trade-off s relativ e t o cost , packagin g etc . Wit hprope r desig n an d integratio n an yo f thes e valv e design s coul d provid e rol l 'e

r protectio n in-use . Wit hthi s backgroun d o n HDGV fue l syste mconfigurations , safet yrequirements , and HDG V onboar d syste mcharacteristics , i t i s no wpossibl e t o addres s som e 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 and addresse s potentia l impact s o f HDGV onboar d o n fue l syste msafet yconsiderations . D . HDGV

Onboar d Safet yIssue s 1 . Introductio n Whil e non e o f th e comment s receive d regardin g 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 and heavy-dut yvehicl e onboar d systems . T o avoi d repeatin g muc ho f wha t ha s previousl ybee n discussed , thi s segmen t wil l primaril yfocu s o n uniqu e HDGV onboar d safet yconsiderations . Th e analysi s presente d i n Sectio n I V regardin g tamperin g and defect s and refuelin g operatio n safet yappl yequall yt o HDGV s and wil l no t b e repeate d here . Th e potentia l problem s ar e simila r and th e sam e basi c straightforwar d engineerin g solution s ca n b e used . Also , th e extensiv e analysi s i n Sectio n V regardin g in-us e fue l syste msafet 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 addin g a n onboar d syste m woul d directional yincreas e in-us e ris k ove r tha t no waccepte d wit hpresen t HDGV fuel/evaporativ e emissio n systems .

### -85

- However , a s wa s discusse d above th e fue l system configuration s an

d the safet ytes t requirement s fo r HDG V fue l tank s ar e somewha t differen t fro mlight-duty , s o some discussio n o f distinc t safetytes 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 design consideration s for HDG V fue l systems . Th e Bureau o f Moto r Carrie r Safet y(BMCS ) ha s fue l systemsafet y regulation s whic happl yt o al l HDGVs , an d NHTSAha 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 ydesign consideration s related t o BMC S requirements . Following thi s i s a discussio n o f the effect s o f NHTSA' s cras htes t requirements . a . BMC S Requirements/Consideration s BMC S ha s establishe d fue l syste mrequirement s for HDGV s t o insur e thei r structura l an d in-us e integrity . A s par t o f thes e requirements , HDG

V fue l tank s mus t be capabl e o f passing the the safet yventing systeman d the 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 the refueling ven t orific e woul d be somewha t large r wit ha

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

d woul d be verysimila r in design an d configuratio n excep t fo r caniste r siz e an d vapo r line length . O f cours e , 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 the structura l integrit y an d the material s use d in ke ysystemcomponent s jus t a s theydoP.8 7

-86

- no wwit hothe r component s o f th e fuel/evaporativ e system . Thus , som e component s o f th e HDG V onboar d syste m(notabl yth e rollove r valve ) ma ynee d t o b e constructe d o f meta l t o provid e impac t resistanc e and th e flammabilit yprotectio n demande d i n th e safet yventin g test . Also , wit hregar d t o impac t resistance , th e on e optiona l side-mounte d tan k model , woul d b e subjec t t o tw o additiona l safet ytest s (dro p tests ) designe d t o evaluat e th e tank' s impac t resistance . Aside-mounte d fue l tan k woul d likel y utiliz e a rollove r valv e mounte d integra l t o o r 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 a n additiona l desig n consideratio n fo r side-mounte d fue l tanks . Fro ma n in-us e safet yperspective , th e impac t resistanc e and overal l integrit yo f rollove r valve s o n fram e 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 HDGV fue l tanks .

b . NHTS ARequirements/Considerations I n additio n t o BMC 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 coverag e involve s a singl e movin g barrie r tes t (3 0 mph ) whic hdoe 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 locatio n o f th e fue l tank , and th e fue l syste mmus t b e designe d s o a s no t t o lea k mor e tha n on e ounc e o f fue l pe r minute . A s wa s tru e o f BMC S requirements , an acceptabl e schoo l bu s onboar d syste mi 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 onboar d syste mcomponent s (rollove r valve , charcoa l canister , critica l vapo r lin e and vapo r lin e connection s betwee n th e to p o f th e fue l tan k and th e rollove r valve ) woul d al l b e evaluate d i n th e test . Desig n measure s simila r t o thos e describe d fo r passenge r car s and 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 ke ycomponents .P.8 8

-87

- Th e crashworthines s discussio n i n Sectio n IV- Aand th e furthe r option s discusse d i n Sectio n V addresse d specifi c safet ydesig n 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 and experienc e t o assis t i n prope r design , and specifi c engineerin g measure s hav e bee n suggeste d t o dea l wit hpotentia l concerns . I n conclusion , HDGV onboar d system s d o no t introduc e any ne wo r significan t problem s t o manufacturers ' attempt s t o desig n saf e fue l system s capabl e o f meetin g NHTS Aand BMC S safet yrequirements . Straightforward , viabl e engineerin g solution s ar e availabl e t o addres s al l problem s tha t hav e bee n identified . Therefore , onboar d system s ar e expecte d t o b e integrate d int o HDGV fue l system s withou t reducin g th e system' s abilit yt o mee t al l applicabl e Federa l safet yrequirements . 3 . Summar y A s wa s mentione d i n th e light-dut ysectio n o f thi s report , EPA' s philosophyi n evaluatin g th e safet yimplication s o f requirin g onboar d control s (includin g 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 and 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 desig n requirement s relate d t o implementin g HDGV onboar d systems , and 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 , and saf e fue l syste m design s ar e achievabl e byall . E . Cos t and Leadtim e Consideration s EP Aha s receive d n o comment s whic hdirectl yaddres s specifi c HDGV

onboar d safet ycos t and leadtim e implications . However , a n analysi s o f th e cost s and leadtim e necessar yt o implemen t HDGV

onboar d control s safel yi s a n 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 HDGV onboar d safet ycosts ; th e secon d discusse s HDGV leadtim e requirement s and describe s th e basi s fo r EPA' s leadtim e estimates . Som e 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 EP Aanalysi s whic hdevelop s tota l HDGV

onboar d syste mcost s i n 198 4 dollars.[17 ]P.8 9


### -88

- 1 . ' Safet yCost s A s wa s tru e o f light-dut yonboard safet ycosts , the cost s neede d t o implemen t HDG V onboard control s fal l in severa l areas . R& D typ e cost s wil l be incurred , som e newor modifie d component s wil l be neede d whic hma yslightl yaffec t vehicl e operating costs , an d safetycertificatio n testin g wil l be necessary . However , befor e beginning a discussio n o f thes e costs , i t i s valuabl e t o discus s howEPA' s HDG V evaporativ e emissio n contro l requirement s impac t onboard safet ycosts . A s wa s describe d i n the light-dut ysectio n o f the report , a n onboard system(even thos e fo r HDGVs ) i s in man yway s a

n extrapolatio n o f curren t evaporativ e emissio n contro l technolog

yan d the tw

o 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 the safet ydesign consideration s associate d wit honboar d system s relate d t o meeting BMCS/NHTS Arequirement s or providing in-us e assuranc e have alread

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

yneede d i s simpl ya n extensio n o f tha t whic halread y exists . Noting the "incremental " natur e o f onboar d safet yin terms o f the magnitud e o f the tas k an d actua l cos t relativ e t o evaporativ e systems , i t i s nowpossibl e t o describ e the component s whic hfacto r int o onboard safet ycosts . Basically , the integratio n o f safet yint o a fue l system incorporating a

n onboar d systeminvolve s fou r 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 ytesting , an d 4 ) weigh t penalt y(or added fue l consumption) . Th e paragraph s tha t followdescrib e howeac ho f the cos t component s ar e affecte d b yonboard safety . T o begi n with , some researc han d developmen t wil l have t o be performe d t o safel yintegrat e onboar d control s int o HDG V fue l systems . EPAha s estimate d tha t the tota l design an d developmen t cos t require d t o incorporat e onboar d system s in HDG V fue l system s i s abou t $34,20 0 pe r famil yor $1.5 0 pe r vehicl e (ove r 10,00 0 lbs 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 a n onboard systemwit hthe 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 yin the design an d developmen t proces s an d ye t i s onl yon e par t o f the tota l effort , onl ya fractio n o f the tota l cos t shoul d be 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 beP.9 0


### -89

- small . Th e sam

e reasonin

g 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 onboard safet ycost s relate s t o specifi c hardwar e tha t ma ybe require d t o insur e fue l system safety . EP

Aha s estimate d cost s for thre e specifi c items whic h have bee n identifie d a s potentia l component s t o be include d a s par t o f the onboard systemdesign explicitl yfor 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 necessar

yt o safel yincorporat e a rollove r valve , pressur e relie f mechanism , or othe r onboard hardware . HDG V rollove r valve s shoul d no t diffe r in cos t fro m light-dut yvalve s sinc e the ywoul d essentiall ybe the same . Therefore , the light-dut y estimat e o f $3.0 0 ti$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 be neede d fo r onboar d systems incorporating a mechanica l fillnec k seal , nearl yal l HDGVs woul d requir e it s use . EPA' s analysi s price s thi s devic e at $2.50.[13 ] At thi s point , thi s estimat e i s considere d t o be ver yconservative , sinc e the possibilit yexit s tha t the presen t pressur e relie f devic e can be modifie d t o perfor mthi s function . Th e fina l onboar d safet yhardwar e cos t account s for an y fue l system

modification s tha t woul d be necessaryin 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 be 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 the fue l system' s vapo r line s ma ybe required . EPAha s estimate d a tota l modificatio n cos t t o be $0.5 0 pe r fue l tank . Onl ypar t o f thi s tota l cos t woul d be require d fo r safet ypurposes . However , becaus e safet y inherentl yenter s int o the decisio n t o mak e an ymodifications , i t i s difficul t t o acces s wha t par t o f the tota l modificatio n cos t shoul d be allocate d t o safety ; perhap s hal f ($0.2 5 pe r fue l tank ) coul d be considere d a s drive n b ysafet yrelate d concerns . Summing u

p the thre e individua l safet yhardwar e cost s yield s a tota l estimate d figur e i n the 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 overhead an d profit . Consequently , in orde r t o obtai n the retai l pric e equivalen t cost , thes e estimate s mus t be multiplie d b

ya marku

p factor . Presently , a marku p facto r valu e o f 1.2 7 appear s representative.[33 ] Therefore , afte r integratio n o f the marku p factor , a tota l retai l pric e equivalen t HDG

V safety-relate d hardwar e cos t fall s withi n the rang e o f $7.3 0 t o $11.10 .P.9 1

-90

- Th e thir d componen t o f safet ycost s i s fo r an ysafet y testin g tha t woul d b e necessary . Unlik e light-dut ytes t costs , EP Aha s no t thoroughl yinvestigate d HDG V safet ytes t costs . However , safet ytes t cost s wer e estimate d i n a n attemp t t o determin e th e approximat e magnitud e o f th e pe r vehicl e HDGV 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 resultin g cost/vehicl e o f $0.2 5 i s ver yminima l i n th e long 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 resultin g fro madde d safet y hardware . Th e amoun t o f weigh t adde d t o vehicl e fro ma rollove r valv e o r 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 tha n lighte r weigh t vehicles , les s tha n $0.2 5 i n adde d fue l cost s wil l resul t fro mthei r inclusio n int o th e HDGV onboar d system.[21 ] Atota l onboar d safet ycos t i s calculate d bysummin g al l fou r individua l componen t costs . Tota l capita l cost s pe r famil yaverag e abou t $230,000 , and th e pe r vehicl e cost s rang e fro m$8.1 0 t o $11.9 0 o r abou t 20-2 5 percen t o f th e tota l cos t dependin g o n th e typ e o f rollove r valv e used . 2 . Leadtim e I f EP Awer e t o implemen t a n HDG V onboar d requirement , i t woul d b e necessar yt o allo wmanufacturer s enoug hleadtim e t o adequatel yprepar e fo r th e requirement . Th e HDGV preparatio n proces s woul d involv e th e sam e individua l task s tha t woul d ente r int o th e light-dut yprocess : syste mdesign , development , testing , tooling , certification , and safet yevaluation . Althoug htw o o f thes e leadtim e task s (certificatio n and safet y evaluation ) woul d involv e somewha t differen t procedure s fo r HDGVs , the ywil l essentiall yrequir e th e sam e amoun t o f tim e and 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 leadtim e require d b yHDGV manufacturers , an d Figur e 2 5 whic hshow s th e parallel/sequentia l progressio n o f th e individua l leadtim e component s woul d b e essentiall yth e sam e fo r HDGVs . O f th e variou s leadtim e component s show n i n Figur e 25 , al l bu t tw o woul d b e essentiall yth e sam e fo r HDGV s a s the ywoul d fo r light-dut yapplications . Thes e tw o ar e certificatio n an d safet yevaluation . I n bot hcases , th e HDGV processe s appea r a s thoug hthe ywoul d tak e les s tim e 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 ,P.9 2

-91

- Tabl e 6 HDGV Fue l Tan k Safet yTes t Cost s Estimat e 1 . BMC S Requirements : 2 test s pe r HDGV

fue l syste mconfiguratio n (Safet yVen t Tes t and Leakag e Test ) Conservativ e Cost/Tes t Estimate : $2,00 0 7 HDGV Fue l Tan k Configuration s Tota l BMC S Safet yTes t Cost : $28,00 0 2 . NHTS ARequirements : 1 tes t pe r HDGV

fue l syste mconfiguratio n (3 0 mp hmovin g barrier ) Conservativ e Cost/Tes t Estimate : $30,00 0 2 Schoo l Bu s Configuration s ( 2 manufacturers , 1 config./manufacturer ) Tota l NHTS ASafet yTes t Cost : $60,00 0 3 . Tota l HDG

V Fue l Tan k Safet yTes t Cost : $88,00 0 4 . Cost/Vehicl e (Amortize d a t 1 0 percen t ove r 5 year s o f

vehicl e sales*) : $0.2 5

* Vehicl e sale s wer e estimate d a t 90,000/yea rP.9 3

-92

- 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 engineerin g judgment . Thi s coul d sav e considerabl e time . A s fa r a s safet yevaluatio n goes , HDG V fue l tan k test s performe d t o mee t BMC S requirement s woul d b e muc hsimple r t o perfor m

tha n NHTSA' s safet ycras htest s fo r passenge r car s and 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 compariso n t o test s whic h involv e multipl e crashe s wit hrollover. ) Therefore , th e amoun t o f tim e allowe d fo r light-dut ycertificatio n (10-1 2 months ) and 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 leadtim e fo r HDG V onboar d i s quit e reasonable . Thi s i s especiall ytru e whe n on e consider s th e developmen t wor k alreadycomplete d an d th e "incremental " natur e o f onboar d i n relatio n t o curren t evaporativ e emissio n systems . EPA' s 24-mont hleadtim e estimat e i s supporte d b ypas t experienc e wit hpreviou s HDGV evaporativ e emissio n rulemakings . Thes e rulemaking s includ e th e Californi a Ai r Resource s Boar d origina l 197 8 6. 0 g/tes t HDGV evaporativ e emissio n standar d whic hwa s implemente d wit hjus t 2 1 month s o f leadtime.[48 ] Th e stringenc yo f thi s standar d wa s increase d fo r 198 0 mode l yea r HDGV s allowin g onl y2 g/test . [49 ] Whil e thi s stricte r standar d wa s promulgate d wit h3 7 month s o f leadtime , manufacturer s ha d t o mee t th e 197 8 standar d first , whic heffectivel ylimite d th e leadtim e 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 h2 4 month s o f leadtim e wa s EPA' s 198 5 HDGV standard . I n eac ho f thes e thre e rulemakings , manufacturer s face d leadtim e factor s identica l t o th e one s tha t woul d accompanya n onboar d requirement , includin g safety . Sinc e manufacturer s wer e abl e t o safel yand 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 , and sinc e th e magnitud e o f th e onboar d implementatio n tas k i s similar , manufacturer s shoul d als o b e abl e t o safel yand effectivel yintegrat e onboar d int o vehicl e fue l system s wit h2 4 month s leadtime . A s fa r a s safet ydevelopmen t and evaluatio n i s concerned , EPA' s HDGV

leadtim e estimat e i s als o supporte d byth e pas t experienc e o f BMC S and NHTS Ai n implementin g variou s HDGV fue l syste mrequirements . I n 1973 , BMC S extende d it s safet ytes t requirement s t o includ e previousl yunaffecte d non-side-mounte d (frame-mounted ) HDGV fue l tanks . Thi s requiremen t wa s implemente d wit hjus t 1 8 month s o f leadtime.[50 ] Als o i n 1977 , FMVS S 30 1 wa s extende d t o includ e schoo l buses , and thi sP.9 4

-93

- requiremeh t wa s implemente d wit h1 7 month s o f leadtime.[51 ] Thi s experienc e indicate s tha t 2 4 month s o f leadtim e allow s manufacturer s sufficien t tim e 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 tim e 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 tha n a yea r i s availabl e fo r actua l fue l tan k safet ytests , schoo l bu s cras htesting , o r an ydesire d compute r simulation . Thi s allow s adequat e leadtim e t o properl yintegrat e safet yint o HDGV onboar d system s especiall ysinc e manufacturer s ca n utiliz e and expan d safet ytechnolog yuse 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 ydevelopmen t whic hwoul d b e require d ha s alreadytake n plac e wit hth e identificatio n and resolutio n o f suc hpotentia l safet yissue s a s rollove r protectio n and fue l tan k pressur e relief . Consequently , a 24-mont hleadtim e perio d woul d provid e manufacturer s wit hsufficien t opportunit yt o develo p saf e and effectiv e onboar d systems . Whil e th e curren t leadtim e estimat e o f 2 4 month s i s reasonabl e fo r al l vehicl e model s includin g HDGVs , EP Ai s sensitiv e t o manufacturer s concern s regardin g leadtim e requirements . EP Ai s committe d t o providin g manufacturer s th e leadtim e necessar yt o implemen t onboar d control s safel yand effectively . Consequently , EP Awoul d includ e HDGV s a s par t o f an yoveral l consideratio n o f a shor t phase-i n perio d fo r onboar d controls . F . Summary/Conclusio n Th e purpos e o f thi s sectio n wa s t o identif yand addres s th e potentia l effect s onboar d control s coul d hav e o n a HDGV manufacturer' s fue l syste msafet ydesigns . Afte r analyzin g th e potentia l safet yconcern s relate d t o implementin g HDGV onboar d systems , EP Aha 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 and correspondin g 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 fe wuniqu e consideration s d o exis t (i n par t becaus e o f difference s i n testin g requirements , tan k 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 , beyon d tha t no wpresen t wit htoday' s HDGV fuel/evaporativ e system . Thi s applie s t o bot hcomplianc e wit hth e applicabl e Federa l safet ystandard s and 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 , andP.9 5


### -94

- tha t whil e fina l choice s regardin g exac t systemdesign s li e wit hthe manufacturers , saf e fue l syste mdesign s ar e achievabl e b yall . EP

Aestimate s tha t HDG V safetycost s contribut e abou t 20-2 5 percen t o f the tota l HDG V onboard systemcos t an d shoul d fal l withi n the rang e o f $8.1 0 t o $11.90 . Wit hregard t o leadtime , EPA' s analysi s indicate s tha t 2 4 month s shoul d provid e HDG

V manufacturer s wit hadequat e tim e t o prepar e for the saf e an

d effectiv e implementatio n o f onboard controls .-95

-

VIII . Conclusio n EP Aha s investigate d and analyze d eac ho f th e potentia l onboar d syste msafet yissue s raise d b yth e commenters . Afte r carefull yconsiderin g al l o f th e potentia l impact s a n onboar d syste mcoul 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 engineerin g solution s exis t fo r eac ho f th e potentia l problem s identified . Furthermore , n o increas e i n ris k nee d occu r o r b e accepte d becaus e o f th e presenc e o f an onboar d system . Onboar d equippe d vehicle s ca n b e designe d t o pas s FMVS S 30 1 and provid e a leve l o f in-us e fue l syste m integrit yequa l t o o r bette r tha n 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 regardin g exac t onboar d syste mdesign s li e wit hth e manufacturers , and eac h manufacture r wil l choos e th e approach/syste mwhic hprovide s th e bes t balanc e o f cost , safety , and othe r ke yfactors . EP Awoul d no t adop t a n onboar d requiremen t unles s i t wa s clea r tha t saf e fue l syste mdesign s wer e available . Thi s repor t demonstrate s thi s t o b e th e case . Saf e fue l syste mdesign 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 onboar d control s and lea d t o a ne t improvemen t i n 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 desig n optio n tha t coul d contro l refuelin g emissions , reduc e evaporativ e emission s and a t th e sam e tim e improv e fue l syste msafety . Manufacturer s ca n and ar e expecte d t o desig n and implemen t onboar d system s i n a manne r whic hprovide s a t leas t th e sam e leve l o f fue l syste msafet ya s achieve d o n presen t vehicles . I n addition , a numbe r o f desig n option s and othe r measure s ar e availabl e wit honboar d systems , whic hsugges t tha t fue l syste m safet yin-us e ca n b e improve d alon g wit hth e incorporatio n o f onboar d contro l systems .P.9 7

-96

- IX . Reference s 1 . Letter , Thoma s Hann a MVMAan d Georg e Niel d AI At o Le e Thoma s U S EPA , Decembe r 22 , 1986 . 2 . Letter , Bria n O'Neil , IIH S t o Le e Thomas , U S EPA , Septembe r 23 , 1986 . 3 . Letter , Ralp hHitchcoc k 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 EP A Gasolin e Marketin g Study , Novembe r 8 , 1984 , docke t A-84-07 . 5 . Letter , Clarenc e Ditlow , Cente r fo r Aut o Safet y t o U S EPA , Marc h, 1987 . 6 . "Surve yo f Evaporativ e Emissio n System s Conditio n o f In-Use , Hig hMileag e Automobiles" , AP I Publicatio n 4393 , February , 1985 . 7 . Bor g Warne r Contro l System s Catalog , Februar y1986 . 8 . "Studyo f Gasolin e Volatilit yand Hydrocarbo n Emission s fro mMoto r Vehicles" , U S EPA , AA-SDSB-85-5 , Novembe r 1985 . 9 . "Summar yand 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 EP A AA-SDSB-87 , Marc h1987 . 10 . Letter , T.M . Fisher , Genera l Motor s t o Jame s B . Weigol d 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 Regulator yStrategie s fo r th e Gasolin e Marketin g Industr yNovembe 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 Regulator ySraegie 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 . "Onboar d Contro l o f Vehicl e Refuelin g Emission s Demonstratio n o f Feasibility" , AP I Publicatio n 4306 , Oc t 1978 . 15 . "Vehicl e Onboar d Refuelin g Control" , AP I Publicatio n 4424 , Marc h1986 .P.9 8



### -97

- 16 . "Evaluatio n o f the Feasibilit yo f Liqui d Fillnec k Seals, " U S EP

AAA-SDSB-86-003 , Decembe r 1986 . 17 . Evaluatio n o f Ai r Pollutio n RegulatoryStrategie s for 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 . "Evaluatio n o f Federa l Moto r Vehicl e Safet yStandar d 301-75 , Fue l SystemIntegrity : Passenge r Cars, " DO T HS-806-335 , Januar y1983 . 20 . Moto r Vehicl e Safet yStandard No . 301-75 , Fue l Syste mIntegrity : 3 9 F R 10588 , Marc h21 , 1974 , PART 571 ; S 301-75-5.1 , 5.2 , 5.3 , and 4 0 F R 48352 , Octobe r 15 , 1975 , PAR T 571 : S 301-75-5.1 , 5.2 , 5.3 , 5.4 . 

### 21 . Letter , Davi d E . Martin , G Mt o Barr

yFelrice , NHTSA , Marc h24 , 1986 . 22 . Not e fro

mBo bWilliams , NHTSA , t o Glenn Passavant , U S EP Aincluding 3 compute r fil e printouts , Novembe r 13 , 1986 . 23 . "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 . 24 . " APerspectiv e on Automobil e Cras hFires" , SAE 850092 , C . Warner , M . James , R . Wooley . 25 . "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 . 26 . IIH S Pres s Release , February25 , 1987 . 27 . An

n Arbo r News , "'Smart ' Suspensio n SystemInclude s Sensors ; Computers, " Ann Arbo r News , Newhous e New s Service , Marc h1 , 1987 . 28 . "Spille d Fue l Ignitio n Source s an d Countermeasures, " Johnson , N. , DO T Contrac t No . HS-4-00872 , Repor t No . 2310-75-118 , September , 1975 . 29 . "Cost s o f Onboar d Vapo r RecoveryHardware" , Jac k Faucet t an

d Muelle r Associates , February1985 .P.9 9

-98

- 30 . "Repor t o n Qualit yChange s fo r 197 7 Mode l Passenge r Cars " USDL-76-1376 , BL S Novembe r 1976 . 31 . "Repor t o n Qualit yChange s fo r 197 6 Mode l Passenge r Cars, " USDL-75-626 , BL S Novembe r 1975 . 32 . "Cos t Estimation s fo r Emissio n Contro l Relate d Components/System s an d Cos t Methodolog yDescription, " EPA-460/3-78-002 , Marc h1978 . 33 . "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 . 34 . "Cos t o f Cras hTestin g t o Assur e Fue l Syste m Integrit yfo r Onboar d Systems, " EP AMemorandum , Rober t Johnso n t o th e Record , U.S . EPA , OAR , OMS , ECTD , SDSB , Septembe r 2 , 1986 . 35 . Conversatio n wit hR . Hitchcock , NHTSA , Marc h28 , 1986 . 36 . "Tra p Oxidize r Feasibilit yStudy" , U.S . EPA , OANR , OMSAPC , ECTD , SDSB , Marc h1982 . 37 . "Characterizatio n o f Fuel/Vapo r Handlin g System s o f Heavy-Dut yGasolin e Vehicle s ove r 10,00 0 Poun d GVW" , Jac k Faucet t Associates , Septembe r 1985 . 38 . "Evaluatio n o f Ai r Pollutio n Regulator yStrategie s fo r th e Gasolin e Marketin g Industry" , U S EPA , OAR , EPA-450/3-84-012a , Jul y1984 . 39 . Memorandu m

t o File , Revie wo f Genera l Motor s Heav y Dut yEngine/Value d Certificatio n Procedures , Tea m I V Certificatio n Branch , Augus t 4 , 1986 . 40 . Memorandu m

t o File , Revie wo f For d HD E Certificatio n Procedures , Tea mI V Certificatio n Branch , Augus t 5 , 1986 . 41 . 4 9 CF R Par t 393.6 5 t o 393.67 . 42 . Conversatio n wit hJi mFeiten , GM , Marc h16 , 1987 . 43 . Conversatio n wit hBo bBisaro , Ford , Marc h16 , 1987 . 44 . Moto r Vehicl e Safet yStandar d NO . 301-75 , Fue l Syste mIntegrity : 4 0 F R 48352 , Octobe r 15 , 1975 , PAR T 571 : S 301-75-5. 4 and 4 1 F R 36026 , Augus t 26 , 1976 , PAR T 571 : S 301-75-5. 4-99

- 45 . " 4 9 CF R 393.6 7 (c)(7)(ii) . 46 . Base d o n a W P o f 1 0 ps i fo r Emc o Wheato n Mode l A600 0 and OP WMode l 7 H diese l fue l nozzles . 47 . Conversatio n wit hJi mBrittell , DOT/BMCS , Februar y 18 , 1987 . 48 . Publi c Hearin g t o Conside r Amendment s t o Californi a Fue l Evaporativ e Emissio n Tes t Procedure s fo r 197 8 and Subsequen t Mode l Gasoline-Powere d Vehicles , Resolutio n No . 76-15 , Marc h31 , 1976 . 49 . Publi c Hearin g o n Propose d Change s t o Regulation s Regardin g Vehicl e Evaporativ e Emissio n Standard s fo r 198 0 and Subsequen t Mode l Moto r Vehicles , Resolutio n No . 76-45 , Novembe r 23 , 1976 . 50 . BMC S Regulations , Par t 393-Part s and Accessorie s Necessar yfo r Saf e Operation s (Fue l Systems) : 3 6 F R 15444 , Augus t 14 , 1971 , an d 3 7 F R 4340 , Marc h2 , 1972 . 51 . FMVS S 301 , 4 0 F R 48352 , Octobe r 15 , 1975 .