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# OAR Box 1856 Prepped byKeeia Richards



### Document

Number: 

# 7DII-A-0 8 Docket Number: 

# A-87-1 1

Printed 11/24/200812:41:50PM Sheet 71 of 82

# fi-miF/ 

# ^V'/TM i-fi-ot P. 2

Summaryan

d Analysi s o f Comment s o n th e Recommende d Practic e fo r th e Measuremen t o f Refueling Emission s

March , 198 7

Standard s Developmen t an d Suppor t Branc h Emissio n Contro l TechnologyDivisio n Offic e o f Mobil e Source s Offic e o f Ai r an

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

Summaryan

d Analysi s o f Comment s o n th e Recommende d Practic e fo r th e Measuremen t o f Refueling Emission s
I . Introductio n A s a resul t o f concern s abou t the emission s whic hoccu r whe n gasolin e vapor s ar e displace d fro mfue l tank s during th e refueling o f moto r vehicles , EPAha s bee n examining th e nee d fo r the contro l o f thes e refueling emission s an d the method s t o d o so . On e suc hmetho d involve s the collectio n o n th e vehicl e o f th e displace d hydrocarbon s an d th e measuremen t o f th e effectivenes s o f the refueling vapo r contro l system . Thi s typ e o f contro l i s referre d t o a s onboar d contro l o f refueling emissions . On Augus t 22 , 1985 , EP Atransmitte d t o intereste d partie s two technica l report s concerne d wit hth e measuremen t o f refueling emissions . On e report , "Refueling Emission s from Uncontrolle d Vehicles,"[1 ] detaile d EPA' s baselin e emission s measurement s o f refueling emission s an d th e second report , "Draf t Recommende d Tes t Procedur e fo r th e Measuremen t o f Refueling Emissions" , [2 ] presente d a tes t procedur e fo r th e determinatio n o f th e effectivenes s o f onboar d contro l o f refueling emissions . Thes e report s wer e accompanie d b ya draf t recommende d practice , "Subpar t C - Refueling Emission s Tes t Procedure."[3 ] Recipient s o f th e report s an d draf t tes t procedur e wer e requeste d t o reviewan d provid e comment s o n EPA' s recommende d tes t procedure , including comment s on th e tes t parameter s an d the tes t equipment . A s a resul t o f on-going EPAanalyse s o f th e tes t procedur e issue s an d the comment s provide d b yth e reviewers , EP

Arevise d the tes t procedure . O n Apri l 10 , 198 6 EPAconvene d a technica l meeting t o presen t an d discus s th e revise d refueling tes t procedures . I n additio n t o th e ora l comment s provide d during th e meeting , EPArequeste d tha t th e participant s provid e writte n comment s o n th e revise d tes t procedure . Comment s o n bot hthe origina l an d revise d tes t procedure s wer e receive d fromth e following organizations :

America n Petroleu

mInstitut e (API ) Californi a Ai r Resource s Boar d (CARB ) Chrysle r Corporatio n Ford -Motor Compan

y Genera l Motor s Corporatio n (GM ) Moto r Vehicl e Manufacturer s Associatio n (MVMA ) Nissa n Researc han d Development,•Inc . Radia n Corporatio n Toyot a Moto r Corporatio n

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Thi s documen t present s a summaryo f th e comment s o n th e recommende d refueling tes t procedure , EPA' s analysi s o f th e issue s raise d b

yth e commenters , an d the resulting change s mad e t o th e recommende d tes t procedure . Th e remainde r o f thi s documen t i s subdivide d int o tw o majo r sections . Sectio n I I present s the summaryan d analysi s o f tes t procedur e issues . Th e comment s receive d o n a particula r issu e ar e firs t identifie d an d the n followe d b

yEPA' s analysi s an d response . Sectio n I I i s subdivide d int o si xsubsections . Thes e subsection s address : tes t parameters , fue l tank heating , facilit yrequirements , caniste r loading , preconditioning , an d miscellaneou s issues . Th e fina l section , Sectio n III , i s an overal l descriptio n o f th e tes t procedur e whic hha s bee n develope d a s a resul t o f the comment s an d EPA' s analysi s o f th e comments . Th e Appendi xfollowing Sectio n II I describe s th e caniste r testing progra mcarrie d ou t i n suppor t o f th e analyse s i n thi s document . II . Summaryan

d Analysi s o f th e Comment s A . PrimaryParameter s Affecting Refueling Emission s I n the draf t recommende d procedure , five keyparameter s affecting refueling emission s wer e identified . Thes e parameter s were : dispense d fue l temperature , differentia l temperatur e betwee n dispense d fue l temperatur e an d fue l tank liqui d temperature , fue l volatility , fue l dispensing rate , an d fue l leve l prio r t o refueling . Th e value s fo r thes e key parameter s directl yaffec t refueling emission s an d wer e chose n wit hth e goa l o f insuring emission s contro l fo r mos t al l expecte d in-us e conditions . T o do this , the value s o f eac h paramete r wer e chose n at approximatel yth e 90t hpercentil e poin t fromdistribution s o f in-us e surveydata . Tes t paramete r value s a s originall ypropose d i n th e draf t recommende d procedur e ar e liste d i n Tabl e 1 . Revision s hav e bee n mad e t o thre e o f th e fiv e tes t value s fo r the parameter s a s a resul t o f comment s receive d an d furthe r EPAanalyses . Whil e th e reason s fo r thes e change s ar e discusse d i n th e remainde r o f thi s sectio n an

d subsequen t sub-sections , the revise d value s ar e liste d her e i n Tabl e 2 fo r eas e o f comparison . 1 . Temperatur e Specification s fo r Dispense d Fue l an d Liqui d Fue l I n Th e Vehicl e Tank I n commenting o n th e stringenc yo f th e refueling tes t parameters , a numbe r o f moto r vehicl e manufacturer s too k th e positio n tha t the value s wer e overl ystringent . Th e manufacturer s state d tha t th e selectio n o f th e 90t hpercentil e o f bot hth e dispense d fue l temperatur e an d th e tank temperatur e woul d resul t i n greate r tha n th e 90t hpercentil e o f refueling event s being represente d b yth e tes t procedure . Accordin g t o thes e manufacturers , the tes t value s selecte d i n th e draf t tes t procedur e woul d represen t approximatel yth e 99t hpercentil e o f refueling events . -3

-Tabl e 1
Draf t Recommende d Procedure , Critica l Tes t Parameter s

Paramete r 1 . Dispense d Temperature , T D 2 . Temperatur e Differential,A T
3.Volatility , RV P

4 . Dispensin g Rat e i 5.Fue l Leve l i Meanin g Temperatur e o f dispense d fue l Tan k temperatur e minu s dispense d fue l temperatur e Tes t fue l volatilit y expresse d i n Rei d Vapo r Pressur e Flo wrat e o f fue l a s i t i s dispense d Leve l o f fue l i n vehicl e prio r t o refueling . Percen t o f capacit y t o neares t 0. 1 U.S . ga l Valu e 8 8 + 2° F

+ 2 t o + 5 ° F
11. 5 + 0. 5 ps i

8-1 0 gal/mi n
10 %Tabl e 2
Revise d Critica l Tes t Parameter s

i U l I Paramete r 1 . Dispense d Temperature , T D 2.Tank temperatur e T T 3.Volatility , RV P

4 . Dispensin g Rat e

5.Fue l Leve l Meanin g Temperatur e o f dispense d fue l Soa k are a temperatur e Tes t fue l volatilit yexpresse d i n Rei d Vapo r Pressur e

Flo wrat e o f fue l a s i t i s dispense d

Leve l o f fue l i n vehicl e prio r t o refueling . Percen t o f capacit yt o neares t 0. 1 U.S . ga l Valu e 81-84° F 8 0 + 3° F I n rang e o f 8 t o ' 11. 5 ps i (Fina l determinatio n t o b e mad e o n result s o f Volatilit yStudy ) Refuelin g measurement : 9. 8 + 0. 3 gal/min . Caniste r loading : 3- 4 gal/min . 10 %P. 7

Th e commenter s ar e correc t i n thei r basi c contentio n tha t the selectio n o f the 90t hpercentil e for th e dispense d fue l temperatur e an

d fue l tank temperatur e wil l resul t i n th e combine d percentil e . being highe r th e individua l percentiles . EPAdisagrees , however , wit hthe assertio n tha t th e tes t value s woul d represen t th e 99t hpercentil e o f refueling events . Firs t o f all , th e parameter s ar e no t full yindependen t variables , making i t difficul t t o asses s the combine d probabilit yo f occurrenc e o~

f extreme values . Second , bot hparameter s d o no t hav e t o b e a t thei r 90t hpercentil e value s t o generat e hig h emissions . A s the valu e o f on e o f th e parameter s rise s beyond tha t point , the othe r can fal l correspondingl ybelo wit s 9 0 percen t valu e an d stil l produc e overal l highemissions . Therefore , t o analyz e th e tota l effec t o f thes e parameter s o n refueling emissions , EPAwen t bac k t o the basi c fiel d surve y dat a an

d constructe d a

n estimate d emissio n rat e distributio n fro mth e fue l an

d tank temperatur e data . Th e dispense d temperatur e an d AT dat a use d i n thi s distributio n wer e take n fro ma 197 5 gasolin e temperatur e surve y conducte d fo r the America n Petroleu mInstitut e (API ) b yth e Radia n Corporation , the same dat a tha t wa s use d i n th e draf t recommende d procedur e report.[4 ] Th e temperature s ar e fromth e four ozone-pron e region s i n the country(show n i n Figur e 1 ) fo r the critica l month s o f MaythroughSeptember . Th e fue l volatilit ywa s assume d t o equa l the ASTMuppe r limit . Refueling emissio n rate s wer e calculate d fro mth e surveydat a using th e following emissio n facto r equatio n develope d b yEP A fro mrefueling tes t dat a fro m uncontrolle d vehicles:[1 ] Emission s (g/gal ) = -5.90 9 -0.0949(AT ) +0.0884(T D ) +0.485(RVP ) Th e distributio n o f the estimate d refueling emissio n rate s i s presente d i n Figur e 2 . Assuming the individua l 90t hpercentil e temperatures , T D =88°F , AT=+2°F , an d the fue l RVP=11.5 , th e resulting emissio n facto r i s 7.2 6 g/gal . A s ca n b e see n from Figur e 2 , thi s valu e (7.2 6 g/gal ) represent s approximatel yth e 93rd percentil e o f the calculate d distributio n fo r summe r refueling events . Radia n Corporatio n performe d a simila r analysi s i n a repor t submitte d t o EPAa t the Apri l 1 0 workshop.[5 ] Radian' s analysis , whic hinclude d consideratio n o f relativ e refueling amounts , indicate d tha t the specifie d tes t parameter s requir e system s tha t contro l ove r 9 9 percen t o f th e refueling case s during ozone-pron e seasons . Whil e no t disagreeing wit h Radian' s basi c approach , EPAbelieve s tha t ther e ar e othe r factor s whic hmus t b e considere d i n a n overal l stringenc y evaluation . Perhap s chie f among thes e factor s i s th e assume d driving patter n use d t o evaluat e systempurge . A s wil l be see n late r i n th e discussion s o f caniste r preconditioning , EPAha s use d a driving sequenc e o f thre e trip s pe r daya s th e basi s fo r systemevaluation . Thi s patter n allow s a fairl ygenerou s amoun t o f caniste r purg e an d represent s typica l condition s
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O O 0) U l 3D l

0 1

o

U l

I o o Figur e2 SUMME RREFUELIN GEMISSIO NFACTO RDISTRIBUTIO N

FO RSELECTE D CITIES *
MIDPOIN T 0 . .2000 0 .4000 0 .6000 0 .8000 0 1 .000 0 1 .200 0 1 .400 0 1.600 0 1.800 0 2.000 0 2.200 0 2.400 0 2.600 0 2.B00 0 3.000 0 3.200 0 3.400 0 :i . fiooo 3.B00 0 • 4 .11011 0 4:200 0 4. 4 00 0 4.6O0 0 4.800 0 5.000 0 5.200 0 5.400 0 5.600 0 5.800 0 6.000 0 6.200 0 6.400 0 6.600 0 6.800 0 7.000 0 7.200 0 7.400 0 7.600 0 7.800 0 8.000 0 8.200 0 8.400 0 B.600 0 B.HOO O 9.000 0 MISSIN G TOTA L COUN T

0 0 0 1 1 0 4 5 8 1 1 1 3 1 0 1 9 2 6 3 5 3 7 4 1 5 6 6 5 10 8 13 4 1 1 6 10 7 12 9 12 8 13 9 15 1 15 9 13 9 1 1 0 12 4 9 0 7 6 5 5 6 2 7 2 6 7 7 0 4 0 3 1 1 6 8 5 4 1 0 52 8 300 1 •

• • • X • X
• • X X • XX X • xxx x • x'xxxx x •xxxxxxx •xxxx x •xxxxxxxxxx •xxxxxxxxxxxx x •xxxxxxxxxxxxxxxxx x •xxxxxxxxxxxxxxxxxx x •xxxxxxxxxxxxxxxxxxxxx •xxxxxxxxxxxxxXXxxxxxxxxxxxxx •xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx •xxxxxxxxxxxxxxxxxxxxxxxxxxxXXXxxxx x •XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX X •XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXxxxxx •xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx x •xxxxxxxxxxXXxxxxxxxxxxxxxxxxXXxxxx x •XXXXXXXXXXXXxxxxxxxxxxxxxxxxXXXXXX X •XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXxxxx x •xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx x •xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx x •XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXxxxx x •XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXxxxx x •XXXXXXXXXXXXxxxxxxxxxxxxxxxxXXXXXX X •xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx x •xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx x •xxxxxxxxxxxxxxxxxxxxxxxxxxxx •xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx x •XXXXXXXXXXXXXXXXxxxxxxxxxxxxxxxxxx x • xxxxxxxxxxxxxxx'xxxxxxxxxxxxxxxxxxx •xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx x •xxxxxxxxxxxxxxxxxxx x •xxxxxxxxxxxxxxx x •xxxxxxxx •XXXX • XX X • X X • X
• E F - .5.90 9 -0.0949(AT ) • Atlanta , Boston , Chicago , Cleveland , Detroit , Houston , Lo s Angeles , Louisville , Miami , Midland , Oklahom aCity , Philadelphia , Pittsburgh , Sa nFrancisc o

xxxxxxxxxxxxxxxxxx x XXXXXXXXXXXXXKXXXXXAXXXXXXXXXXX A XXXXXXXXXXXXXXXXXXXXXX X xxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxx XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX X XXXXXXXXXXXXXXXXXXXXXXXXXXXXXxxxxxxxxxxx x xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx x xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx x xxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxx xx x

RV P = AST M

Maximu m

allowabl e fo r th e month s involved ,

c oP.1 0

rathe r than an uppe r limit . It s us e ha s the effec t o f lowering the overal l stringenc yo f th e tes t procedur e fromtha t represente d b

yth e fue l parameters . Asecon

d stringenc yconsideratio n i s th e fac t that , a s describe d i n th e technica l repor t accompanying th e origina l draf t procedure[2] , th e temperatur e dat a use d represente d smoothe d averag e values . Thus , fo r example , th e dispense d fue l temperature s wer e five da yaverages , an

d di d no t contai n th e high s tha t dail yvalue s woul d give . No r di d the yrepresen t th e dail ymaximun values , whic hthe repor t indicate d woul d typicall yb e 4 t o 7° F abov e th e average . Anothe r facto r describe d i n th e origina l repor t whic hha s no t bee n directl yinclude d i n th e procedur e i s th e effec t o f fue l weathering o n refueling emissions . Th e presenc e o f weathere d residua l fue l i n th e fue l tan k a t th e time o f refueling , rathe r than unweathere d fue l a s use d i n th e tes t procedure , woul d b e expecte d t o increas e refueling emission s b y perhap s 0. 5 g/gal . EPA' s decisio n no t t o us e weathere d fue l i n the tan k a t thi s time i s anothe r facto r reducing th e overal l stringencyleve l o f th e refueling test . I t woul d b e possibl e t o us e weathere d fue l an d mak e some adjustmen t i n th e temperatur e parameters , bu t thi s chang e woul d hav e n o beneficia l effec t on the tes t an d woul d ad

d th e complexit yo f havin g t o handl e two differen t tes t fuels . Give n al l thes e factors , th e precis e overal l stringenc yo f the tes t procedur e i s difficul t t o determine . EPAbelieve s tha t i t i s sufficien t t o insur e contro l a t nearl yal l expecte d conditions , a s wa s it s origina l goal . Th e chie f impac t o f mor e demanding tes t parameter s i s t o increas e require d caniste r size s t o hol d the increase d amount s o f generate d vapors . Thi s resul t i s no t undesireable , s o lon g a s n o othe r syste mchange s ar e require d whic hmigh t markedl yincreas e th e margina l cos t o f compliance . I f thi s wer e th e case , the n mor e detaile d analysi s o f tes t conditio n stringenc ymigh t b e justifie d t o determin e whethe r some relaxatio n migh t b e appropriate . 2 . Fue l Volatilit y Th e draf t recommende d procedur e specifie d tha t th e tes t fue l hav e an RVP o f 11. 5 psi . Thi s volatilit yrepresent s th e RVP o f summe r commercia l fue l a s use d i n curren t EP Aemissio n factor s tes t programs , a s wel l a s being th e AST Mclas s C volatilit yuppe r limi t fo r summe r month s i n th e ozon e pron e area s o f th e country . MVMA , i n it s comments , advocate d tha t the fue l use d i n the refueling tes t procedur e hav e th e same RVP a s tha t o f EPA' s curren t certificatio n tes t fuel , i.e. , 9 psi . MVM Aunderstoo d an

d agree d wit hth e Agency' s desir e t o eliminat e th e presen t discrepanc ybetwee n summe r commercia l fue l volatilit yan d the curren t certificatio n fue l volatility . MVMA' s solutio n is , however , t o limi t commercia l summe r fue l t o

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9. 0 RV P a s oppose d t o specifying tha t th e refueling tes t fue l volatilit yequa l presen t commercia l fue l volatility , a s th e recommende d tes t procedur e specified . Th e issu e o f tes t fue l versu s commercia l fue l volatilit y i s currentl ybeing examine d b ythe Agenc yan

d EP Ai s studying fue l volatilit yt o establis hthe bes t overal l approac ht o dealin g wit hthi s issue . Whateve r the resolutio n o f tha t process , EPAintend s ' t o adop t thos e result s fo r refueling testin g a s well . Th e draf t procedur e use d 11. 5 RV P simpl y becaus e i t approximate d th e curren t in-us e situation . Tha t choic e wa s no t intende d t o represen t resolutio n o f th e RVP issue . Th e procedur e shoul d mor e properl yb e viewe d a s potentiall yusing a fue l wit hvolatilit yanywher e i n th e rang e o f possibl e option s being considere d b yEPAa t thi s time , i.e. , anywher e from8 t o 11. 5 psi . A n additiona l volatilit yconcer n wa s raise d b yNissan . I n it s comments , Nissa n expresse d concer n abou t variation s i n th e RVP o f tes t fuel s an d questione d howi t ca n b e controlled . Thi s concern , i.e. , the nee d t o limi t th e weatherin g o f tes t fue l i n the fue l car t s o a s t o minimiz e tes t variability , i s shared b

yEPA . Th e revise d procedur e contain s th e requiremen t fo r the collectio n o f a fue l sampl e an d measuremen t o f th e RVP immediatel yprio r t o the measuremen t o f refueling emissions . EPArecognize s tha t thi s i s a wors t cas e requiremen t wit h respec t t o it s effect s on tes t facilit yan d personne l resources . EPAi s ope n t o al l suggestion s o n equipmen t desig n o r tes t dat a o n th e rat e o f fue l weathering i n th e fue l car t whic hwoul d allowles s frequen t measuremen t o f th e RVP o f th e tes t fuel . 3 . Fue l Dispensing Rat e Th e fina l are a o f comment s wit hrespec t t o th e tes t parameter s concerne d the recommende d valu e fo r th e fue l dispensing rate . I n th e draf t recommende d procedure , the specifie d rang e o f 8 t o 1 0 gallon s pe r minut e (gpm ) wa s identifie d a s covering th e majorit yo f th e refueling event s whil e minimizing nuisanc e shutof f o f th e fue l nozzle . Severa l commenter s too k issu e wit hthi s rang e fo r a variet yo f reasons . AP I state d tha t some vehicle s ca n no t b e fuele d a t a rat e a s higha s 8 t o 1 0 gpman d tha t prematur e nozzl e shu t of f a t highfueling rate s i s associate d wit hsom e fille r nec k designs . MVM

Acommente d tha t spit-bac k i s highl yprobabl e a t a fueling rat e o f 1 0 gpm whe n th e tank approache s th e 9 5 percen t ful l level , especiall ywit ha liqui d seal . MVM Astate d tha t CARB limit s fueling t o the 9 0 percen t tank leve l a t a fueling rat e o f 1 0 gpm , applicabl e wit hth e 198 7 mode l year . MVM Aals o state d tha t the specifie d fueling rat e rang e o f 8 t o 1 0 gpmi s to o broad an

d recommende d a fueling rat e specificatio n o f 9.0+_0. 2 gallons/minut e t o improv e tes t repeatabilit yan d test-to-tes t an

d lab.-to-lab . correlation .

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EPAagree s tha t the occurrenc e o f nuisanc e shutoff s an d fue l spillag e mayb e a functio n o f fille r nec k desig n whe n vehicle s ar e fuele d a t highflowrates . However , i t i s EPA' s belie f tha t .th

e design o f a refueling contro l systemwhic hi s capabl e o f controlling prematur e nozzl e shutof f an d avoiding spit-bac k a t expecte d in-us e fue l dispensing rate s i s th e responsibilit yo f th e moto r vehicl e manufacturers . Lackin g spit-bac k control , fue l spillag e fromthi s sourc e coul d b e a majo r sourc e o f refueling emissions . Thus , a fue l fille r systemtha t prevent s spit-bac k a t th e uppe r limi t o f th e dispensing rat e i s integra l t o th e effectiv e contro l o f refuelin

g emissions . A t th e same time , EPArecognize s th e fac t that , give n vehicle s designe d t o operat e a t curren t maximu mvalues , gasolin e marketing pressure s woul d be expecte d t o lea d t o increase d in-us e despensing rate s i n th e future . I n orde r t o preven t suc ha situation , i t i s likel ytha t some control , voluntaryo r otherwise , woul d b e require d ove r in-us e dispensing rates . EPAbelieve s tha t a maximu m dispense d fue l rat e o f 1 0 gpm i s reasonabl e base d upo n curren t in-us e conditions . Th e draf t procedur e reporte d tha t mos t refueling s tak e plac e a t 1 0 gpmo r less ; als o CARB ha s alread yspecifie d 1 0 gp mfo r testing t o demonstrat e complianc e wit hit s refueling contro l program . Thus , 1 0 gp

mwil l continu e t o b e use d a s th e approximat e maximu mflowrate . Turning t o the questio n o f variabilit yi n tes t result s betwee n test s and/o r betwee n laboratorie s wit hrespec t t o th e rat e a t whic hfue l i s dispensed , EPAbelieve s tha t some variabilit yi n result s can be attributabl e t o thi s factor ; i.e . fue l dispensing rate . EPAals o believe s that , i n a refueling emission s test , th e uppe r limi t o f the dispensing rat e i s normall yth e importan t criteria . I n selecting a toleranc e band fo r the fue l dispensing rat e t o addres s th e tes t variabilit y concern , EPAals o recognize d th e nee d fo r th e us e o f a valu e whic hwoul d b e achievabl e a t a relativel ylowcost . EPA believe s tha t a toleranc e ban d o f approximatel y3 percen t a t a flo wrat e o f approximatel y1 0 gpm , i.e . + 0. 3 gpm , wil l achiev e bot hobjectives . Combining th e selecte d toleranc e band wit hth e objectiv e o f holding the lowe r limi t clos e t o 1 0 gpm wit ha minima l exceedanc e o f 1 0 gp ma t th e uppe r limi t resulte d i n th e flowrat e specificatio n o f 9. 8 +

_0. 3 gpm . Testing conducte d a t EPAwil l normall ydispens e fue l a s clos e t o 1 0 gpm withou t exceeding th e 10. 1 gp mlimi t a s possible , sinc e thi s valu e woul d be expecte d t o b e the mos t difficul t tes t condition . B . - Fue l Tank Heating Heating o f th e fue l i n th e fue l tank wa s require d i n the draf t recommende d procedur e t o bring th e liqui d fue l an d fue l vapor s int o equilibriu m a t the require d tes t temperature . Th e tes t procedur e include d a metho d fo r heating th e fue l tank -11

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usin g a singl e hea t blanke t whic hallowed , th e fue l vapo r an d liqui d fue l t o reac han equilibriu m conditio n befor e testing . Concern s raised i n the comment s covere d a wid e rang e o f areas . Thes e concern s ar e summarize d below . I n it s comments , MVM Astate d tha t th e fue l tank configuratio n greatl yinfluence s the abilit yt o hea t th e fue l an d t o achiej/ e th e 3° F vapo r t o liqui d temperatur e differenc e required i n the procedure . MVM Aquestione d th e feasibilit yo f the recommende d procedur e t o achiev e the require d heating o n a variet yo f tank configurations . MVM Arequeste d tha t EP A demonstrat e the feasibilit yo f the procedur e o n severa l tank configurations . Dat a submitte d b yFord showe d a

n inabilit yt o achieve th e require d vapo r temperatur e wit ha singl e heatin g blanke t o n a MercuryLynx . Th e questio n o f ho wtemperatur e measurement s o n in-us e vehicle s (us e o f an externa l thermocoupl e wa s propose d i n th e draf t procedure ) wer e t o be mad e wit hplasti c fue l tank s wa s als o raise d b

yMVMA . Anothe r aspec t o f th e fue l temperatur e measuremen t issu e whic hwa s raise d b ycommenter s wa s th e capabilit yt o read th e tru e fue l temperatur e whe n heating a nearl yempt yfue l tank . Th e thermocoupl e woul d hav e t o b e ver y clos e t o the hea t blanke t whe n the 1 0 percen t fue l volum e wa s bein g heate d an

d MVM Astate d tha t thermocoupl e reading s could , a s a result , b e influence d b yth e hea t blanket . Comment s on th e subjec t o f fue l tank heating als o identifie d test-to-tes t variabilit ya s a concern . Toyot a stated tha t the initia l boiling poin t o f 11. 5 RVP fue l i s unde r 88° F an

d tha t thi s fue l property , i n combinatio n wit hth e specifie d temperature s o f the fue l tank an d o f th e fue l dispensing system , woul d resul t i n highvapo r losse s an d resultan t tes t t o tes t variability . Specifying a heating rat e wa s recommende d a s a mean s o f limiting th e rat e o f boilin g o f the fue l an

d t o avoi d variabilit yi n tes t result s cause d b y variabilit yi n th e heating rate . Concern s abou t th e fue l tank heating procedur e an d temperatur e measuremen t requirement s suc ha s thos e expresse d b y th e moto r vehicl e manufacturer s wer e share d b yEPA . A s a resul t o f it s experience , EPAse t ou t t o revis e th e tank an d dispense d fue l temperature s i n a n effor t t o eliminat e th e nee d fo r externa l tank heating an d tank fue l temperatur e measurement .

• Using the emissio n facto r equatio n give n earlier , alternativ e dispense d fue l an d tank temperature s ca n b e define d whic hwoul d yiel d approximatel ythe same emissio n condition s a s the tes t parameter s otherwis e selecte d o n th e basi s o f tes t stringency . Th e approac huse d wa s t o selec t a fue l tank temperatur e equa l t o ambien t laboratorycondition s (thu s eliminating the nee d fo r tank heating ) an d t o determin e a dispense d fue l temperatur e yielding th e same emissio n rat e a s

•12

-P.1 4

di d th e initia l tes t conditions . Temperature s develope d fro m the equatio n wer e 80° F + 2° F fo r th e fue l tank temperatur e (80° F wa s selecte d becaus e i t i s the temperatur e maintaine d i n the EPA' s Moto r Vehicl e Emissio n Laboratoryvehicl e soa k area) , 83° F + 2° F fo r th e dispense d fue l temperatur e an d th e requiremen t tha t th e temperatur e o f the dispense d fue l b e 1 ° t o 3° F highe r than the soa k are a temperature . Thes e temperature s resulte d i n _ a mea n refueling emission s valu e o f 7.2 9 g/ga l whic hcompare d veryfavorabl yt o the valu e o f 7.2 6 g/ga l fo r th e origina l tes t conditions . Th e 80° F fue l tank temperatur e ca n b e readil yachieve d withou t the nee d t o hea t o r measur e th e temperatur e o f th e fue l i n the vehicl e tank throughth e proces s o f soaking th e vehicl e a t th e require d temperatur e fo r a pre-specifie d soa k period . EPAchos e a soa k perio d o f si x hour s a s sufficien t t o accomplis hthi s task . Following th e Apri l 10 , 198 6 meeting, , manufacturer s provide d comment s o n th e revise d temperatur e specifications . I n thei r comments , theyexpresse d strong suppor t fo r th e concep t o f selecting a fue l tank temperatur e equa l t o ambien t laboratoryconditions . However , a numbe r o f manufacturer s commente d tha t th e +2° F soa k are a toleranc e wa s to o restrictive . G

Mreporte d tha t maintaining tigh t contro l o f roo mambien t temperatur e i n it s large r laboratorie s ca n b e very difficult . EPA' s mai n concer n i n designating th e +

_2° F toleranc e wa s t o limi t advers e impact s o n tes t variability . I n respons e t o the comments , EPAperforme d additiona l analyse s o n the effect s o f tes t temperatur e tolerance s o n refueling emission s variability . Th e conclusio n reache d i s tha t expansio n o f the soak are a temperatur e toleranc e ban d ca n b e accommodate d i f accompanie d b ya n adjustmen t i n th e dispense d fue l toleranc e ban d t o retai n approximat e equivalenc yi n th e refueling emission s toleranc e ban d attributabl e t o tes t variabilit yi n thes e temperatures . A s a result , the fue l tank temperatur e i s specifie d a s 80°+3° F an d th e dispense d fue l temperatur e i s specifie d a s 81 ° t o 84°F . EP Abelieve s tha t maintaining th e reduce d dispense d fue l .toleranc e band wil l no t b e excessivel yburdensome . Unde r thi s approach , th e dispense d fue l woul d onl ynee d t o b e heate d t o 81 ° - 84°F , whic hwoul d substantiall yreduc e an yproblem s wit hrespec t t o th e boilin g poin t o f th e fue l i n th e fue l car t an d th e associate d change s i n th e fue l RVP . EPAbelieve s that. , th e us e o f thes e temperatur e specification s wil l alleviat e th e concern s expresse d b

yth e manufacturer s withou t an yreductio n i n th e require d contro l o f refueling emissions . C . Facilit yRequirement s Th e recommende d refueling tes t procedur e require s the us e o f a seale d housing fo r evaporativ e determinatio n (SHED) , simila r t o wha t i s no wuse d fo r evaporativ e emission s testing wit hmino r alteration s t o accommodat e fue l dispensing . Th e SHE D i s require d fo r th e actua l refueling tes t an d fo r loading

-13

-P. U

o f the caniste r t o breakthrough . Comment s o n th e facilit y requirement s o f the tes t procedur e addressed : 1 ) th e us e o f a SHE D t o determin e caniste r loadin g t o breakthrough ; 2 ) th e impac t o f the tes t o n facilit yrequirements ; an d 3 ) th e locatio n o f the refueling hos e an d nozzle . 1 . SHE D Us e for BreakthroughDeterminatio n Commenter s suggeste d th e us e o f procedure s othe r tha n a SHE D t o determin e caniste r loadin g t o breakthrough . I t wa s pointe d ou t tha t some contrac t laboratorie s whic hmeasur e exhaus t emission s d o no t hav e SHE D equipmen t an d would , therefore , b e unabl e t o performrefueling test s becaus e o f th e lac k o f a SHED . Th e facilit yrequiremen t impac t (a s discusse d below ) wa s als o a concer n fo r thos e facilitie s wit hSHEDs . A procedur e involving repeate d refueling s t o load th e caniste r withou t the nee d fo r a SHE D wa s suggeste d a s a n alternative . I n additio n t o comment s recommending the eliminatio n o f the us e o f a SHE D whe n loading th e canister , comment s wer e mad e recommending change s t o th e SHE D loadin g procedur e itself . MVM Astate d tha t the procedur e shoul d be writte n s o a s t o preven t th e continue d forcing o f vapor s througha caniste r whic hi s loade d t o breakthrough . MVM Abelieve s tha t th e procedur e a s propose d woul d loa d the canister s pas t breakthrough , an

d a s a solutio n recommende d using a reduce d fueling rate , e.g. , 3 gallons/minute , during caniste r loading t o breakthrough . MVM Aals o recommende d tha t the sampl e pick-up poin t fo r detecting breakthroughb e clos e t o th e caniste r rathe r than remotel ymounte d i n the SHE D a s specifie d i n th e recommende d procedure . MVM Abelieve s tha t reducing th e respons e time fo r breakthroughdetectio n wil l preven t continue d forcing o f vapor s througha caniste r alread yloade d t o breakthrough . Responding firs t t o th e basi c issu e o f needing a SHE D t o detec t breakthrough , EPAagree s tha t a caniste r loading approac hwhic hwoul d no t requir e the us e o f a SHE D t o determin e caniste r breakthroughi s desirabl e s o a s t o simplif ytestin g an d reduc e resourc e requirements . Us e o f th e SHE D wa s propose d b yEPAs o a s t o addres s th e following concern s associate d wit h the us e o f a sampl e pick-u p locate d a t th e canister . First , tha t a smal l transien t puf f o f vapo r fro mth e canister , prio r t o breakthrough , coul d b e interprete d a s breakthroug han d thereb yresul t i n incomplet e loading o f the canister . Second , tha t relativel ysmal l ai r current s around the vehicle , a s coul d occu r i n a larg e room , coul d dissipat e breakthroughvapor s and lea d t o delaye d detectio n o f breakthrough . Asmal l quantit yo f dat a recentl ycollecte d b yEP Ausin g curren t evaporativ e emission s canister s suggest s tha t smal l prematur e puff s o f vapo r mayno t b e a significan t concern . Ther e is , however , no wayo f telling whethe r thi s dat a i s

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-P.1 6

applicabl e t o th e large r an d possibl yreconfigure d canister s whic har e anticipate d fo r us e wit honboar d refueling systems . Ther e i s als o no informatio n o n th e effect s o f ai r current s aroun d the vehicl e o n breakthroughdetection . EP Acontinue s t o believe , therefore , tha t the SHE D need s t o b e use d i n determining caniste r breakthroughloading . A t th e same time , the Agenc ywoul d welcom e the submissio n o f furthe r dat a o n thi s are a whic hmigh t lea d t o a non-SHE D base d approach . MVMA' s concer n wit hth e SHE D procedur e i s tha t breakthroughwil l occur significantl ybefor e detectio n becaus e o f th e sampl e pick-u p location . A s a resul t o f th e detectio n delay , MVM

Ai s concerne d tha t a fueling rat e o f 1 0 g/mi n wil l caus e a significan t amoun t o f additiona l vapo r t o b e transmitte d t o th e caniste r beyond th e actua l breakthroug h point . EPAagree s tha t detectio n la g wil l resul t i n some degre e o f caniste r loading beyond breakthroughan d tha t th e degre e o f loading beyond breakthroughwil l depend o n th e refueling rate . However , sinc e th e objectiv e o f th e caniste r loadin g procedur e i s t o achiev e loading s t o at . leas t breakthrough , thi s fac t o f itsel f i s no t troubling . Wha t i s o f concer n i s th e increase d amoun t o f variabilit yi n breakthrough measurement s a t highfue l flowrates . Fo r thi s reason , some reductio n i n th e fueling rat e woul d be acceptabl e provide d loadin g t o a_

t leas t breakthroughwa s achieved . Testin g conducte d b

yEPAa t a fueling rat e o f 3 t o 4 gallon s pe r minut e ha s show

n tha t repeatabl e loading condition s shoul d result . Th e fueling flowrat e during th e caniste r loading procedur e will , therefore , b e specifie d a s 3- 4 gallons/minute . 2 . Testin g Capacit y Commenting o n th e impac t o f the tes t o n facilit y requirements , Toyot a state d tha t adoptio n o f th e recommende d refueling tes t procedur e woul d resul t i n eithe r a significan t reductio n i n th e testing capacit yo f existing facilitie s o r woul d requir e significan t facilit yexpansio n t o retai n presen t testing capacity . Th e cost s relate d t o the modificatio n and/o r constructio n o f expande d tes t facilitie s wa s a significan t issu e t o a numbe r o f commenters . EPArecognize s tha t incorporatio n o f % th e refueling tes t procedure , o r fo r tha t matte r an yothe r ne wtesting requirement , int o th e existing emission s testing procedur e wil l impac t tes t facilitie s t o some extent . EPA , lik e th e manufacturers , i s desirou s o f holding t o a minimumth e impac t o f th e procedur e o n facilit yrequirements . EP Ai s makin g every effor t t o minimiz e the impac t wheneve r possibl e i n developin g th e tes t procedure . I n fact , the revise d procedure , whic hwil l b e describe d furthe r below , ha s a muc hlowe r facilit yimpac t than di d th e previou s draft . Al l comment s o n ho wth e impac t o n facilit yrequirement s ca n be furthe r minimize d ar e encourage d an d welcomed .

15

-P.1 7

I n th e are a o f costs , EPArecognize s tha t som e expenditure s wil l b e necessaryt o expand tes t facilitie s t o accommodat e the demand s o f incorporating th e refueling tes t procedure . However,
- i t appear s that , a s a par t o f overal l cost , thes e impact s wil l b e relativel ysmall . Fo r example , value s use d b

yth e Moto r Vehicl e Manufacturer s Association , whe n viewe d a s a cos t pe r productio n vehicle , represen t onl y approximatel y3 0 cent s pe r vehicle . Eve n thes e value s woul d b e expecte d t o declin e i n th e fac e o f th e procedura l revision s bein g describe d i n thi s document . 3 . Refueling Hos e Locatio n Th e draf t procedur e specifie d tha t th e fue l dispensin g hos e an

d nozzl e b e locate d insid e the SHED . On e commente r questione d whethe r non-permeabl e fue l hose s woul d b e required ; fue l hos e permeability , nozzl e leakage , an d nozzle-to-fue l hos e join t leakag e maycaus e a SHE D contaminatio n problem . During SHE D background an d retentio n validatio n test s conducte d a t EPA' s Moto r Vehicl e Emissio n Laboratory , contaminatio n problem s wer e experience d a s a resul t o f th e locatio n o f th e fue l dispensing hos e an d nozzl e insid e th e SHED . Thi s problem wa s resolve d b

ymoving the hos e an d nozzl e outsid e o f the SHE D an d providing acces s t o the vehicle' s fil l nec k b ya boo t s o tha t onl ythe nozzl e ti p enter s th e SHED . Th e specifi c criteri a develope d fo r th e boo t are : tha t th e apertur e throughwhic hth e nozzl e ti p passe s seal s agains t th e ti p whe n the nozzl e i s inserte d an d close s t o for

ma vapo r tigh t sea l whe n the nozzl e i s no t i n place ; tha t th e boo t b e flexibl e an

d relativel ylon

g s o a s t o avoi d the nee d fo r precis e locating o f the vehicl e i n th e SHED ; an d th e boo t b e larg e enought o facilitat e fre e passag e o f th e nozzl e throug h the boo t an

d ful l operatio n o f the nozzl e insid e o f th e boot . Locatio n o f th e nozzl e an d fue l hos e outsid e o f th e SHE D ha s solve d th e contaminatio n problems . Th e procedur e ha s bee n modifie d t o requir e th e us e o f equipmen t fo r refueling wit hth e refueling hos e an

d nozzl e locate d outsid e the SHED . D . Requiremen t fo r Loading Caniste r t o Breakthrough Commentin g o n th e requiremen t fo r caniste r loading , two commenter s too k issu e wit hth e nee d t o full yload th e caniste r t o breakthrough . MVM Aan d Toyot a state d tha t force d loading o f th e caniste r t o breakthroughi s no t representativ e o f in-us e vehicl e operatio n an d should , therefore , no t b e par t o f th e tes t procedure . Thes e comment s als o claime d tha t loading o f the caniste r i n thi s manne r wil l hav e a negativ e impac t o n exhaus t emissions , o n fue l econom yan d o n driveability . MVMA state d tha t ful l caniste r loading followe d b yon e pre p LA- 4 wil l significantl yad d t o the difficult yo f complyin g wit h exhaus t emission s standard s an d i n meeting fue l econom y objective s an

d wil l resul t i n th e collectio n o f exhaus t

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-P.1 8

emission s an

d fue l econom

yvalue s unde r non-representativ e operating conditions . MVM Aals o believe s tha t ful l loading o f the caniste r remove s an yincentiv e t o provid e a safet ymargi n i n canister , sizing becaus e excessiv e hydrocarbon s hav e t o b e processe d during purging an d thi s wil l caus e driveabilit y problems . On e commente r pointe d ou t tha t th e propose d procedur e di d no t requir e loading t o breakthrougho f th e evaporativ e canister s i n non-integrate d onboar d systems . EPAbelieve s tha t loading canister s t o breakthroughi s an importan t requiremen t o f th e procedur e s o a s t o demonstrat e tha t the systemwil l adequatel ypurg e the caniste r froma full y loaded condition . Th e nee d t o demonstrat e thi s capabilit yi n th e tes t procedur e stem s fromth e wid e variation s whic hexis t i n the metho d o f operatio n o f in-us e vehicles . Sinc e th e degre e t o whic ha caniste r i s purge d prio r t o refueling i s dependen t o n vehicl e operation s preceding refueling , i t i s reasonabl e t o expec t tha t wid e variation s i n th e degre e o f caniste r purg e ca n als o exis t i n in-us e vehicles . Vehicle s use d infrequentl yan d i n shor t tri p operation s wil l experienc e reduced caniste r purging whil e accumulating ho t soa k emission s afte r eac htri p an d repeate d diurna l loading s becaus e o f infrequen t operation . A s a result , thes e in-us e vehicle s ca n be expecte d t o experienc e force d loading o f th e caniste r t o breakthrougho r saturation . Force d caniste r loading t o breakthroughi n th e tes t procedur e is , therefore , no t unrepresentativ e o f a n even t whic hca n occu r o n an in-us e vehicle . Dat a availabl e t o EPAindicat e tha t th e caniste r systemdoe s no t underg o permanen t advers e effect s b ybeing highl yloade d an

d quickl yrecover s it s capacit ywhe n vehicl e operating condition s provid e additiona l purge . Loadin g o f a caniste r t o breakthroughresult s i n a readil yachievabl e an d repeatabl e caniste r loading condition . Retentio n o f th e loadin g t o breakthroughrequiremen t i n th e procedur e thu s provide s a useful , readil yidentifiabl e poin t fo r beginnin g testing . I t i s importan t t o not e tha t loading th e caniste r t o breakthroughi s regarde d b yEPAa s a minimu

mloading conditio n befor e testing . If , becaus e o f it s in-us e operating factors , a vehicl e come s i n fo r testing loade d beyond breakthrough , i t wil l b e teste d a s received . I f system s ar e properl ydesigned , suc hoccurrence s shoul d b e rare ; bu t i f system s ar e no t properl ydesigne d an d frequentl yoperat e beyond th e breakthroughpoint , the n thi s i s a consequenc e o f th e desig n an d th e system s stil l ough t t o b e teste d in tha t condition . Althoug hsome o f the commenter s fel t tha t loading th e caniste r t o breakthroughwoul d hav e a n advers e impac t o n driveability , exhaus t emissions , an d fue l economy , an d therefor e shoul d no t b e include d i n th e tes t procedure , EPA doe s no t agree . First , sinc e caniste r loading t o breakthroug h

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-P.1 9

wil l occur o n in-us e vehicles , manufacturer s wil l hav e t o accommodat e thi s conditio n i n thei r systemdesign s regardles s o f tes t requirements . Manufacturer s wil l hav e t o desig n thei r systems t o operat e satisfactoril ywit hrespec t t o bot hcaniste r purg e an

d driveabilit ybecaus e o f in-us e -considerations . A s fo r exhaus t interactions , EPAha s alway s expecte d tha t evaporativ e system s shoul d be abl e t o begi n th e evaporativ e tes t procedur e fro m a loade d conditio n an d expect s t o introduc e thi s requiremen t apar t from an yonboar d actions . Th e presenc e o f a n onboar d caniste r coul d increas e th e amoun t o f purg e vapor s unde r loaded conditions , bu t no t t o an unmanageabl e degree . A s fo r fue l economy , EPAagree s tha t impact s o n fue l econom ymeasurement s shoul d b e avoided . Th e simples t optio n woul d be t o allowthos e manufacturer s wh o believ e tha t loading th e caniste r t o breakthroughwil l hav e a negativ e impac t o n fue l econom

yt o omi t th e caniste r loading step fo r th e fue l econom ytest . I f thi s approac hwer e unsatisfactory , the n a CAF E adjustmen t migh t hav e t o b e considered . On e revisio n wa s mad e t o th e caniste r loading procedur e a s a resul t o f th e commen t whic hpointe d ou t tha t ther e wa s no loadin g procedur e fo r th e evaporativ e caniste r i n non-integrate d systems . Omissio n o f thi s step i n th e procedur e wa s an oversigh t since , th e inten t o f th e procedur e wa s t o includ e a loading step for the evaporativ e caniste r i n non-integrate d systems . Astep will , therefore , b e adde d t o the procedur e requiring the loading t o breakthrougho f th e evaporativ e caniste r i n non-integrate d system s prio r t o th e vehicl e preconditioning . A s wit hrefueling canisters , thi s step wil l requir e the us e o f the SHE D t o determin e th e breakthroughpoint . E . Vehicl e (Canister ) Conditioning fo r Performanc e o f Refueling Emission s Contro l Tes t Background Th e tes t sequenc e propose d fo r refueling emission s adde d two ne wtest s designe d t o chec k th e capacit yan d purg e capabilit yo f the refueling contro l system , respectively . Bot h o f thes e test s depende d upo n caniste r preconditionin g step s fo r thei r prope r functioning . . .. . Th e refueling capacit ytes t wa s designe d t o ensur e tha t th e overal l vapo r contro l capacit yo f th e caniste r wa s sufficien t fo r a complet e fill-up , i.e . fro m1 0 percen t o f tank volume t o a t leas t 9 5 percen t o f tank volume . Certificatio n tes t vehicle s wer e expecte d t o arriv e a t th e tes t sit e wit h canister s purge d t o a leve l commensurat e wit ha nearl yempt y tank . Prio r t o testing , th e fue l tank woul d b e draine d an d fille d t o 1 0 percen t o f capacit ywit htes t fuel . Sinc e in-us e vehicle s coul d arriv e i n an ycondition , preconditionin g b y5 0 mile s o f driving using tes t fue l o n eithe r th e durabilit y

-18

-drivin

g schedul e o r equivalen t urba n driving wa s proposed . Followin

g th e 5 0 mile s o f driving , th e fue l tan k woul d b e drained an

d fuele d t o 1 0 percen t o f capacity . Followin g thi s preconditioning , th e actua l refueling tes t woul d the n b e performe d t o verif ytha t the refueling syste mindee d ha d adequat e capacit yt o handl e essentiall ya ful l refueling . Th e second , o r purge , tes t bega n wit ha drive-down sequenc e o n "th e dynamometer , consisting o f sequentia l Urba n Dynamomete r Driving Schedule s (UDD S o r LA-4) , alternatin g wit h on e hour ho t soaks . Thi s sequenc e wa s intende d t o us e fue l an d allowrefueling caniste r purge , i n orde r t o subsequentl y perfor ma partia l refueling wit ha n amoun t o f fue l larg e enough t o adequatel ytes t th e system' s purg e capability . T o d o this , the UDD S soa k sequenc e woul d be repeate d unti l approximatel y3 0 percen t o f the tank fue l capacit yhad bee n used . Arefueling tes t woul d the n b e conducte d a s wit hth e capacit ytest , excep t tha t the refueling amoun t woul d approximatel ycorrespond t o th e amoun t o f fue l consume d i n th e drive-down . Th e purpos e o f thi s stag e wa s t o demonstrat e tha t th e refueling contro l systemhad adequat e purg e capacit yt o purg e accumulate d refueling vapors . Comment s Sinc e th e conditio n o f the refueling caniste r prio r t o an y refuelin

g tes t i s veryimportant , i t i s no t surprisin g tha t considerabl e commen t wa s directe d a t the variou s conditionin g step s in th e draf t procedure . Commenter s generall ybelieve d tha t the 5 0 mil e driv e fo r in-us e vehicle s wa s inadequate , an d the yoppose d th e us e o f a conditioning procedur e fo r in-us e vehicle s differen t fromtha t use d o n certificatio n vehicles . Commenter s als o expresse d concern s wit hrespec t t o th e capabilit yo f the 3 0 percen t driv e dow n t o prov e th e purg e capabilit yo f th e system . Commenter s suggeste d severa l alternativ e procedure s fo r conditioning o f the canister s prio r t o performanc e o f the refueling capacit ytest . Fo r certificatio n vehicle s MVM A suggeste d actual * vehicl e driving whil e Toyot a suggeste d starting wit ha ful l fue l tank an d driving eithe r 1 4 hour s o n the durabilit ymileag e accumulatio n procedur e o r 8 0 hour s o f UDDS/ho t soa k operation . Th e America n .Petroleu mInstitut e (API ) suggeste d th e us e o f a 5 0 mil e driv e fo r certificatio n vehicle s a s ha d bee n propose d fo r in-us e vehicles . "Actual" , whil e no t defined , seeme d t o impl yoperatio n o f th e vehicl e eithe r o n a tes t trac k o r o n th e road using an operating schedul e whic hwoul d reflec t actua l consume r driving patterns .

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-P.2 1

Fo r capacit ytesting o f in-us e vehicles , bot hMVM Aand Toyot a suggeste d driving ou t th e fue l containe d i n th e fue l tan k a t the time tha t the vehicl e entere d th e tes t program . MVM Asuggeste d driving 7 5 mile s fo r eac h1/ 4 tank volum e containe d i n the fue l tank . Toyot a suggeste d driving th e vehicl e unti l 1 0 percen t fue l volume remaine d i n th e tank . Commenter s als o questione d the 3 0 percen t drive-down associate d wit hthe caniste r purg e test . The ysuggeste d tha t actuall ydriving ou t a whol e tankfu l o f fue l migh t b e th e onl y reliabl e wayt o verif yprope r systempurg e characteristics . EPAitsel f had indicate d concer n wit hrespec t t o th e adequac y o f the 3 0 percen t drive-dow n becaus e o f the non-linea r natur e o f caniste r purging wit htime . Th e draf t procedur e containe d EPA' s suggestio n tha t a ful l drive-dow n migh t b e required . I n orde r t o effectivel yrespon d t o al l th e concern s ove r caniste r preconditioning whic hhav e bee n raised , EPAha s undertake n an extende d analysi s o f caniste r purg e characteristic s an d vehicl e operating patterns . Fro mthi s analysi s the Agenc yha s derive d a revise d approac ht o preconditioning an d testing refueling contro l canisters . Thi s approac hi s greatl ysimplifie d compare d t o the draf t procedure , an d provide s a mor e accurat e wayt o asses s th e abilit yo f refuelin

g contro l system s t o performproperl yi n actua l use . Th e result s o f EPA' s analysi s ar e presente d i n the following sections . Analysi s 1 . Caniste r H C Purg e Characteristic s T o develo p a

n understanding o f howcanister s purge , EP A performe d a serie s o f test s o n evaporativ e emissio n contro l canisters . Some o f the canister s had bee n i n us e (aged ) o n durabilit ydat a vehicle s an d wer e furnishe d byChrysler , Ford , G Man d Nissa n whil e other s wer e ne wunit s purchase d from dealers . On e relativel ylarg e canister , constructe d b yEPA , wa s als o tested . Th e detail s o f th e testing an d th e tes t result s ar e show

n i n th e Appendix . Th e overal l result s ar e summarize d below . Tw o basi c step s wer e use d i n testing th e desorptio n characteristic s o f carbo n canisters . Th e firs t involve d loading th e caniste r t o an appropriat e leve l wit hrefueling vapors . Th e secon d wa s t o drawai r ove r th e carbo n be d t o purg e i t o f it s hydrocarbo n load . Purg e curve s wer e develope d b ymonitoring th e chang e i n hydrocarbo n load a s a functio n o f the volume o f purg e ai r pulle d ove r the carbo n bed . Th e keyresult s o f the testing ar e shown i n Figur e 3 . Show n ar e characteristi c purg e curve s fo r th e variou s canister s

-20

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# REPRESENTATIV E CURVE S Normqlize d b yCaniste rVolum e

1 0 2 0 Purg e Volum e (cubi c feet/liter ) FIGURE 3 •My
, •H aP.2 3

expresse d a s the weigh t o f hydrocarbon s remove d fromth e caniste r versu s the volume o f ai r draw n throughth e canister . Th e tes t result s hav e bee n normalize d t o a caniste r volum e o f on e lite r t o provid e a standardize d basi s fo r comparisons . I n reviewing the result s o f thi s testing , EPAdecide d tha t the result s o f th e test s on the Chrysle r caniste r shoul d no t b e use d fo r subsequen t analysis . Thi s caniste r showe d , a substantiall ylowe r storag e capacit ythan th e othe r canisters , fo r reason s whic hwer e neve r identified . I n an yevent , a caniste r wit hsuc ha smal l storag e capacit ype r uni t volum e o f charcoa l woul d no t b e expecte d t o b e a reasonabl e choic e fo r us e i n refueling contro l systems . T o characteriz e th e rang e o f characteristic s exhibite d b ythe othe r thre e canisters , EP Aha s use d the Nissa n an

d For d curve s i n it s analysis . A t thi s time , EPAdoe s no t knowho wrepresentativ e o f al l caniste r design s thes e result s are , no r howmuc himprovemen t i n caniste r performanc e coul d be gaine d b yattempt s t o optimiz e charcoa l performance . However , thes e question s ar e no t critica l i n relatio n t o th e primarygoa l o f describing genera l syste m characteristic s an

d designing appropriat e tes t techniques . 2 . Vehicl e Operatio n Evaluatio n o f in-us e vehicl e operationa l pattern s importan t t o a

n onboar d refueling tes t programrequire s consideratio n o f typica l dail yevent s whic hcontribut e t o th e loadin g an d unloading o f the canister . Hydrocarbo n vapor s generate d during evaporativ e diurnal s an d ho t soak s along wit h vehicl e refueling s constitut e caniste r loadin g events . Vehicl e driv e event s caus e caniste r unloading . O n the basi s o f typica l driving patterns , in-us e vehicle s ar e employe d unde r widel yvarying conditions . A s a resul t o f thi s variabilit yi n dail yoperationa l trips , th e loading , a t an yselecte d time , o f a H C vapo r contro l canister , whethe r i t be a refueling contro l caniste r o r a n evaporativ e contro l canister , wil l als o vary . A t on e extreme i s th e conditio n o f multipl e day s wherei n the vehicl e i s no t drive n a t all . Unde r thi s non-drive n condition , th e caniste r wil l experienc e repeate d dail ydiurna l loading s o f H C vapo r an d wil l eventuall y reac ha full yloade d (saturated ) condition ; i.e. , th e canister' s capacit yt o adsorban d retai n H C wil l b e reached . A t th e othe r -extreme i n the rang e o f dail yoperationa l characteristic s i s continuou s lon g tri p operation . Unde r thes e conditions , the caniste r wil l underg o continuou s purging an d th e amoun t o f H C store d i n the caniste r woul d approac hzero . Betwee n thes e limit s li e a wid e variet yo f dail yvehicl e usag e patterns . Typically , vehicl e usag e pattern s migh t

-22

-includ e two employmen t relate d trip s pe r dayan d on e o r mor e trip s fo r othe r purposes . Unde r multipl e vehicl e tri p pe r day operations , the caniste r wil l underg o purging whil e th e vehicl e i s bein g drive n an

d loading du e t o ho t soak s an d th e dail y diurna l whil e th e vehicl e i s parked . T o analyz e overal l system performance , EPAconstructe d a simpl e mode l o f caniste r behavior . Using th e caniste r purg e curve s describe d above , th e mode l wa s abj. e t o trac k caniste r performanc e fo r bot hFor d an d Nissan typ e canisters . I n th e model , eac hdail ytri p i s considere d t o b e equivalen t t o on e LA-4 ; i.e. , 7. 5 mile s o f vehicl e operation . Th e purg e rat e i s expresse d a s the volume o f purg e air , i n cubi c feet , pe r LA-4 . Th e referenc e informatio n store d i n th e mode l i s the characteristi c caniste r purg e curv e fo r on e lite r Ford an

d Nissan canisters . Th e inpu t variable s employe d ar e desire d caniste r siz e an d type , purg e ai r volum e pe r LA-4 , uncontrolle d ho t soa k an d diurna l loading s i n grams , an d the numbe r o f trip s pe r day . Th e output s fromth e mode l ar e tabulation s o f the running tall yo f th e caniste r purge s an d loading s relative t o mile s drive n plu s othe r parameter s whic h can be derive d fro m thes e figure s (e.g. , amoun t o f H C purge d pe r mile) . Running losses , i f any , ar e treate d a s going directl yt o the engin e an d no t impacting loading o r purging o f the canister . Thi s assumptio n i s no t appropriat e fo r al l curren t evaporativ e contro l systemdesigns , bu t EPAbelieve s tha t suc hdesign s wil l no t be foun d o n futur e system s becaus e o f thei r advers e impac t on caniste r purge . I n addition , diurna l loading s ar e treate d a s a constant , neglecting th e fac t that , for example , immediatel yfollowing a refueling , th e fue l tan k woul d be ful l an d essentiall yno diurna l emission s woul d be generated . Thi s mean s tha t the result s fromthe mode l ar e representativ e o f condition s afte r par t o f th e fue l ha s actuall ybee n use d u p an d no t t o be interprete d a s th e ful l time historyo f event s beginning wit ha ful l tank . Th e result s froma typica l ru n o f th e compute r mode l ar e show n i n Figur e 4 . I n thi s case , a simpl e patter n i s illustrate d consisting o f a singl e dail ydriv e followe d b ya ho t soak an

d a diurnal . Th e mode l indicate s tha t afte r onl ya fewrepetition s o f thi s pattern , a n equilibriu

mi s reache d betwee n purging an d loading . Thi s equilibriu mindicate s th e vapo r storag e capacit yavailabl e fo r refueling control . Not e tha t continuing t o operat e o n thi s patter n produce s n o furthe r progres s towar d the full ypurge d capacit yo f th e canister . On e o f the keyeffect s o n systemperformanc e i n thi s exampl e i s the dail ydriving patter n whic hi s assumed . Figure s 5 through7 illustrat e the effec t o f using two , thre e o r four assume d trip s pe r dayinstead o f one . A s ca n b e see n from

-23

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_ 18 0 17 0 - 16 0 - 15 0 14 0 H 13 0 12 0 11 0 - 10 0 - 9 0 8 0 H 7 0 6 0 - 5 0 - 4 0 3 0 2 0 - 1 0 - 0 

# CANISTE R PURG E V S CYCLI C OPERATIO N FIJ3UR E 7 CANISTE R : 4. 3 LNISSA N HOTSOA K: 1 0 g DIURNA L: 2 2 q PURG E : 1 2 C U F

T/ LA- 4 DAIL YTRIP S : 4

- T - 4 0 8 0 12 0 16 0 !0 0 Mile s Drive n

JN >thes e figures , vehicle s operate d o n eithe r a on e o r tw o tri p

pe r daycycl e wil l posses s lowe r refueling capacitie s tha n vehicle s operate d unde r a thre e o r four tri p pe r daycycle . O n the othe r hand , i t i s the cas e fo r al l o f th e driving pattern s tha t th e caniste r reache s a n equilibriu

m conditio n afte r onl ya fewrepetition s o f the dail yoperating pattern . Thes e results , incidentally , hav e bee n derive d fo r a Nissa n typ e caniste r becaus e the iJissa

n caniste r show s th e greates t sensitivit yt o driving pattern s an d make s the cleares t example . For d typ e canister s respon

d t o driving patterns , bu t t o a lesse r degree . Following initia l evaluatio n o f the effec t o f drivin g patterns , EPAchos e t o do it s subsequen t modeling base d upo n a thre e tri p pe r da ysequence . A s wil l b e see n below , thi s patter n ha s als o bee n use d i n the tes t procedur e preconditioning sequenc e development . Thre e trip s pe r da y closel yresembles , the valu e o f 3.0 5 trip s pe r dayi n th e EP A MOBILE 3 mode l for determining the effect s o f mobil e sourc e emissio n standard s o n pollutan t inventories . Fro mth e abov e modeling results , however , i t i s clea r tha t thi s represent s a les s demanding requiremen t than tha t o f a on e o r two tri p pe r da ysequence . Th e overal l effec t o f thi s choic e upo n tes t procedur e stringenc yha s no t bee n quantified . 3 . Effec t o f Purg e Rat e Fo r a give n vehicle , th e othe r keyoperating variabl e whic haffect s refueling systemperformanc e i s th e purg e rate . Th e refueling mode l show s that , holding caniste r siz e constant , the equilibriu

mleve l (whichrepresent s the availabl e refuelin g capacity ) ca n be increase d o r decrease d b ychanging th e ai r purg e rate . Thes e effect s ar e illustrate d i n Figure s 8 an d 9 . Th e effec t o f increasing th e purg e ai r rat e i n th e exampl e use d abov e b

y5 0 percen t i s show n i n Figur e 8 . Th e increas e i n purg e ai r rat e result s i n an increas e i n th e amoun t o f hydrocarbon s whic har e purge d fromth e caniste r a t equilibrium ; i.e. , a

n increas e i n refueling capacity . Conversely , i t i s show n i n Figur e 9 tha t a 5 0 percen t decreas e i n purg e ai r rat e result s i n a reductio n i n th e hydrocarbo n purg e leve l a t equilibrium ; i.e. , a reductio n i n refueling capacity . 4 . Caniste r Sizing . - . . Having develope d a basi c mode l o f refueling syste mloading an d purging , require d caniste r sizing fo r refueling operation s wa s analyzed . Th e require d refueling vapo r capacit yfo r a give n vehicl e wa s determine d using th e uncontrolle d emissio n facto r equatio n develope d i n EPA' s refueling emissio n baselin e stud y(Refueling Emission s fromUncontrolle d Vehicles ; EPA-AA-SDSB-85-6) . An entrainmen t facto r o f 2 0 percen t (base d upo n earl ytes t result s wit ha liqui d sea l system ) an d a safet y margi n o f 1 0 percen t wer e adde d t o thi s basi c rat e t o estimat e overal l require d design capacity . -28

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Th e require d capacit ywa s the n relate d t o th e equilibrium leve l o f the caniste r i n the EPAmodel . Mor e specifically , required caniste r siz e wa s determine d base d upo n th e requirement, , tha t the caniste r hav e th e necessar yrefuelin g vapo r capacit ya t the en d o f the firs t tri p following th e dail y diurna l loadin

g o f the da

ywherei n the caniste r firs t reache d equilibrium . Thi s mean s that , a t equilibrium , th e vehicl e i s expected t o _b

e abl e t o handl e a ful l refueling afte r havin g experience d a dail ydiurna l an d the n driving on e tri p t o th e ga s station . Becaus e o f the tradeof f betwee n purg e rat e an d effectiv e caniste r capacit ydescribe d above , equa l caniste r equilibrium level s and , therefore , refueling capacit yca n b e achieve d from a relativel ywid e rang e o f caniste r size s an d a correspondin g rang e o f purg e ai r flowrates . Caniste r size , fo r equa l refuelin

g capacity , i s inversel yproportiona l t o purg e ai r flo w rate . Thi s relationshi p i s show n i n Figure s 1 0 through1 3 fo r fou r differen t vehicl e types : a smal l car , an averag e car , a full-siz e dual-tank light-dut ytruck , an d a typica l heavy-dut y gasolin e truck . Th e specifi c characteristic s assume d fo r eac h vehicl e ar e give n i n Tabl e 3 . Acoupl e o f commo n characteristic s ar e apparen t fromthes e figures . First , whe n the purg e rat e i s relativel yhighth e Ford typ e canister s generall yrequir e somewha t greate r caniste r volume than do the Nissa n typ e canisters . However , a s th e purg e rat e i s decrease d t o th e lo wend o f th e purg e rate s investigated , the Nissa n typ e canister s ten d t o b e large r tha n the Ford type . Second , the curve s ar e fairl yfla t ove r a broa d rang e o f purg e rates , followe d b ya rapi d upturning i n caniste r siz e a t lo

wpurg e rates . Sinc e bot hdiurna l an d refueling loads , whic har e th e dominan t vapo r sources , ar e proportiona l t o fue l tank size , i t i s possibl e t o normaliz e th e result s fo r al l four vehicle s an d produc e a singl e famil yo f curves . Figur e 1 4 show s th e relationshi p betwee n caniste r volume pe r gallo n o f fue l tank capacit yan

d LA- 4 purg e rat e pe r lite r o f caniste r volume . 5 . Refueling SystemEffect s on Engin e Operatio n Recognizing tha t bot hcaniste r siz e -an d purg e ai r flo w rat e can varywidely , i t i s appropriat e t o investigat e thos e factor s whic hcoul d establis hboundarie s o n thes e parameters . Sinc e a smal l caniste r i s desirabl e frombot ha cos t an d a packaging perspective , designer s can b e expecte d t o us e th e smalles t caniste r possible . Sinc e caniste r siz e decrease s a s purg e ai r flowrat e increase s a n investigatio n o f potentia l uppe r limit s fo r purg e ai r flowrat e i s warranted .

-31

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# CANISTE R SIZ E V S PURG E AI R FLOWRAT E

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Tabl e 3
Vehicl e Parameter s Use d i n Caniste r Sizing Calculation s

Vehicl e Typ e Smal l Ca r Smal l Ca r Averag e Ca r Averag e Ca r LD T (Dua l tanks ) LD T (Dua l tanks ) HD V HD V Fue l Delivery System Fue l Injectio n Carburetio n Fue l Injectio n Carburetio n Fue l Injectio n Carburetio n Fue l Injectio n Carburetio n Fue l Tan k Volume (gal ) 8. 2 8. 2 13. 0 13. 0 38. 0 38. 0 50. 0 50. 0 Ho t Soak

Loadinq 6 9 1 0 1 5 2 9 4 3 3 8 5 7 Diurna l (q ) Loadin q(q )

1 4 1 4 2 2 2 2 6 4 6 4 8 4 8 4 Require d

Refuelin g Capacit y(q) * 6 5 6 5 10 4 10 4 30 3 30 3 39 9 39 9

Refueling capacit yrequire d calculate d fro mrefueling emission s a t tes t condition s (i.e . 7.1 5 gram/gallon ) x8 5 percen t o f tan

k volume x1. 2 (t o accoun t fo r 2 0 percen t entertainmen t wit hliqui d seal ) x1. 1 (t o provid e a 1 0 percen t safet ymargin) .

-36

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1. 8 1. 7 1. 6 1. 5 1. 4 1. 3 1. 2 1. 1 1 0. 9 0. 8 0. 7 0. 6 0. 5 0. 4 0. 3 0. 2 0. 1 0 NORMALIZE D VALUE S FIGUR E 1 4

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5. 1 Basi c Consideration s Contro l o f the powe r outpu t fro ma gasolin e engin e i s accomplishe d b

ylimitin

g th e amoun t o f ai r availabl e t o th e engine , b

ymean s o f a throttl e place d i n th e engin e intak e system . Th e fue l metering systemi s designe d t o provid e fue l i n proportio n t o the amoun t o f ai r allowe d t o ente r th e engine . Throttling o f the intak e ai r suppl ycause s a reductio n i n the pressur e o f the ai r (or ai r an d fue l mixture ) i n th e intak e manifol d downstreamo f the throttle . Thi s reduce d pressur e i n the intak e manifol d downstreamo f th e throttl e provide s a

n essentiall yzer o cos t metho d fo r movin g th e ai r necessar

yfo r purging o f store d hydrocarbon s from a canister . Activatio n o f th e caniste r purg e systemhowever , provide s an additiona l sourc e o f ai r an d fue l t o th e engine . Thi s ai r i s no t unde r th e contro l o f the drive r o f the vehicl e an d th e H C vapo r (fuel ) entraine d i n the ai r i s no t unde r th e contro l o f the engine' s fue l metering system . Purging o f th e hydrocarbon s stored i n a caniste r can , therefore , impac t engin e operatio n throug hperturbation s i n th e amoun t o f ai r availabl e t o th e engin e an

d i n the rati o o f fue l t o ai r supplie d t o th e engine . Th e purpos e o f thi s segmen t o f th e analysi s i s t o develo p a n understanding o f limit s whic hmaybe applicabl e t o caniste r purg e ai r flowan d t o the fue l supplie d b yth e caniste r i f unacceptabl e negativ e impact s o n engin e operatio n ar e t o b e avoided . Astepwis e presentatio n o f th e effect s o f activating the caniste r purg e systemwil l facilitat e th e desire d analysis . 5 . 2 Purg e Ai r A s wa s state d previously , activatio n o f th e caniste r purg e systemwil l allowmor e ai r an d a variabl e amoun t o f additiona l fue l t o reac hth e engine . Th e resulting effec t o n engin e operatio n wil l depend o n th e rang e o f contro l an d rat e o f respons e o f th e engine' s fue l metering system . I f th e rang e o f contro l wer e t o b e exceeded , th e anticipate d resul t coul d b e eithe r a substantia l los s i n powe r o r stalling o f th e engine . Powe r los s woul d b e associate d eithe r wit han extremel yric ho r lea n bu t ignitabl e mixture . Stalling woul d b e associate d wit h eithe r a richening o r leaning o f th e mixtur e beyond th e ignitio n limit . .. . I f th e rang e o f contro l wa s no t exceeded , th e effect s o n engin e operatio n woul d depend o n th e spee d wit hwhic hth e fue l met-erin g systemcoul d compensat e fo r th e perturbatio n cause d b y the ai r an

d fue l coming fromth e canister . I f th e respons e rat e wa s ver yrapi d th e effec t woul d b e fo r a rapi d increas e i n the engine' s powe r outpu t becaus e bot hth e ai r an d th e fue l availabl e t o the engin e increase d an d increase d approximatel y

-38

-P.4 0

i n the correc t relativ e ratio . A s perceive d b yth e driver , th e effec t woul d b e fo r th e vehicl e t o accelerat e withou t a drive r initiate d actio n fo r acceleration . I f th e acceleratio n wa s small , i t coul d g o unnotice d b yth e driver . If , however , th e acceleratio n wa s large , the drive r coul d perceiv e th e acceleratio n a s a los s o f contro l o f the vehicle . On e straightforwar d approac ht o a larg e induce d purg e chang e i s t o simpl yus e a dampe r o r slowl yoperating purg e contro l valve . Suc ha valve , b yintroducing th e chang e i n ai r flowove r a lengthene d period , woul d allowfo r drive r compensatio n a s a par t o f th e norma l driving process . I n thi s way , a fairl ylarg e chang e coul d b e mad e wit hno perceptibl e impact . Eve n so , i t i s wort hevaluating reasonabl e limit s fo r the purg e perturbatio n t o determin e i f suc ha contro l strategy i s eve n needed . O n th e assumption , then , tha t the vehicl e coul d rapidl y adjus t t o th e sudde n onse t o f purge , on e limi t fo r purg e rat e woul d b e th e maximu m acceptabl e powe r perturbatio n i t woul d produce . Th e siz e o f thi s limi t i s estimate d belo w(limit s fro mthe purg e relate d fue l flowwil l be treate d later) . Sinc e vehicle s presentl yd o no t incorporat e system s whic h coul d caus e relativel ylarge , non-drive r induced , change s i n the powe r leve l a t whic hthe engin e i s operating an d consequen t vehicl e acceleration s or decelerations , i t wa s necessarytha t a surrogat e be identified . Vehicl e acceleration s an d deceleration s associate d wit hthe disengagemen t an d engagemen t o f air-conditioning compressor s wer e selecte d a s a guid e t o drive r acceptabl e performanc e perturbation s attributabl e t o powe r change s a t the driving wheels . Thi s informatio n wa s use d in estimating a drive r acceptabl e limi t fo r purg e ai r induce d increase s i n engin e power . Figur e 1 5 show s manufacture r supplie d nomina l value s fo r the powe r require d t o driv e ai r conditioning compressor s o n typica l vehicle s (value s furnishe d b yHond a ar e fo r cit ytyp e operation s an

d are , therefore , no t expresse d i n term s o f vehicl e speed) . Figure s 16 , 17 , an d 1 8 shownomina l engin e brak e horsepowe r (BHP) * curve s wit han d withou t air-conditione r Engin e brak e horsepowe r (usefu l externa l power ) value s wer e derive d fromtypica l chassi s dynamomete r powe r absorptio n curve s wit hallowance s fo r powe r losse s a t th e tir e t o dyn o interface , time s allowance s fo r driv e axl e an d transmissio n efficienc yplu s allowance s fo r th e powe r requirement s o f th e alternator , wate r pump , fan , ai r pum p an d powe r steering pump .

-39

-I o I OL I
rZ U l U J 9 : D O U l ct a: ui 

### o OL 0

_ 

### o (/ > if) U l Q

_ C L 5 O O 

# AI R CON D COMPRESSO R POWE R REQUIREMEN T FIGUR E 1 5 8



### 6 -
5 -
4 - 3 -

1 -
0 A . B . C . D . E . F . Ford . Smal l Car ; Direc t Driv e Ford . Averag e Car , LDT ; Ove r Driv e Ford . Averag e Car , LDT ; Direc t Driv e GM . Larg e Car ; Durabilit yLoad s Hond a Accord ; Cit yAverag e Hond a Civic ; Cit yAverag e

0 D A


### . + 1 1 1 2 0 4 0

VEHICL E SPEE D (MPH ) B O C A D 6 0 8 0

# ENGIN E BH P V S VEHICL E SPEE D

i Q . I 

### a. o _ u 

### o a . u z o 

### z U l SMAL LCA R FIGUR E 1 6

D VE H VE H VEHICL E SPEE D (MPH ) + AU XO VE H + AU X+ AC



### fe

# ENGIN E BH P V S VEHICL E SPEE D

i I Q . 

### I O Q v ^ Q

_ U J 

### o C L U l 

### z o z u AVERAG E CA R FIGUR E 1 7

VE H VEHICL E SPEE D (MPH ) VE H + AU XO VE H -t - AU X+ AC

.K SI u > I 

### a . i a _ 

### oc UJ 

### o a . ui 

## z o z u i 

# ENGIN E BH P VS VEHICL E SPEE D LIGH T DUT Y TRUCK FIGUR E 1 8

0 2 0 4 0 6 0
D VE H + VEHICL E SPEE D (MPH ) VE H + AU

XO VE H + AU X+ A CP.4 5

compresso r loadin

g fo r thre e size s o f vehicle s (smal l car , averag e ca r an

d full-siz e light-dut ytruck) . A t an yselecte d vehicl e speed , th e differenc e betwee n th e wit han d withou t air-conditioning compresso r curve s represent s th e incrementa l chang e in engin e horsepowe r availabl e t o accelerat e the vehicl e whe n the compressor , disengages . Incrementa l increase s i n engin e powe r availabl e t o prope l the vehicl e whe n th e ai r conditioning , compresso r turn s of f wer e extracte d from Figure s 14 , 1 5 an

d 1 6 a t 20 , 3 5 an

d 5 0 mp han

d ar e show

n i n Tabl e 4 a s percentage s o f the BH P require d t o operat e the vehicle . Th e powe r consumptio n figure s i n Tabl e 4 canno t b e use d directl yt o evaluat e purg e rates , becaus e theyar e applicabl e t o outpu t power , whil e an ypurg e perturbatio n wil l impac t tota l engin e power . Total , o r indicated , powe r include s bot houtpu t (brake ) powe r an

d interna l motoring power . However , a t th e relativel ylo

woutpu t (brake ) powe r level s involve d i n th e dat a bein g use d here , i t appear s reasonabl e t o assume tha t losse s withi n th e engin e coul d approximat e th e brak e horsepowe r output . Using thi s approximation , the percentag e chang e i n tota l engin e powe r fo r an averag e ca r whe n th e compresso r cycle s of f at 3 5 mphwoul d be approximatel yon e hal f o f th e 3 1 percen t chang e in brak e powe r show n i n Tabl e 4 , o r abou t 1 5 percent . Similarly , averag e percentag e change s i n tota l engin e powe r for the thre e vehicl e type s ar e abou t 8 , 1 5 an d 1 7 percen t fo r LDTs , averag e car s an d smal l car s respectively . Fo r the two ca r size s only , the averag e chang e i s abou t 1 6 percen t an

d thi s valu e wa s selecte d a s a representativ e uppe r limi t fo r the impac t o f a n increas e i n ai r flowattributabl e t o caniste r purging . Sinc e the incrementa l increas e i n tota l engin e powe r i s directl yproportiona l t o the incrementa l increas e i n ai r flow , th e 1 6 percen t valu e ca n b e applie d directl yt o the purg e ai r flowrate . Conversio n o f th e 1 6 percen t o f engin e ai r flowvalu e t o a volume o f ai r purge d throughth e caniste r wa s derive d fromfue l econom yvalue s fo r the vehicle s on the LA- 4 employing th e assumptio n tha t stoichiometi c air/fue l rati o woul d b e maintaine d throughout . Th e fue l econom yvalue s employe d fo r a smal l car , a

n averag e ca r an

d a full-siz e LD T wer e 52 , 2 5 an d 14. 5 mp g respectively . Avalu e o f 7. 5 mp g wa s assigne d fo r a heavy-dut ygasolin e vehicle . Th e corresponding volume s o f ai r use d b yth e vehicle s o n a n LA- 4 ar e 178 , 36 9 an d 63 7 an

d 123 1 ft 3

. Th e caniste r purg e ai r flowrate s correspondin g t o 1 6 percen t o f the engin e tota l ai r consumptio n s o calculate d ar e 28 , 59 , 10 2 an d 19 7 ft 3 o f ai r pe r LA- 4 fo r a smal l car , a n averag e car , a full-siz e ligh t dut ytruc k an d a heavy-dut y gasolin e vehicl e respectively . Thes e values , rounde d t o 30 , 60 , 10 0 an

d 20 0 ft 3 o f ai r pe r LA- 4 wer e use d a s initia l estimate s o f uppe r limit s fo r caniste r purg e ai r volume s fo r system s characterize d b yth e sudde n onse t o f purg e flow .

-44

-P.4 6

Ai r A s

Vehicl e Spee d 2 0 3 5 5 0 Conditione r Percentage s

Ai r Cond i

Smal l Ca r 4 3 3 6 2 5 Tabl e 4 Compresso r Powe r Requirement s Expresse d o f Powe r Require d T o Powe r Th e Vehicl e A t Thre e Speed s tione r Compresso r Powe r a s Percen t o f Vehicl e Motiv e Powe r Averag e Ca r Liqh t Dut yTruc k 4 0 2 4 3 1 1 6 2 0 1 0

-45 -P.4 7

Referring bac k t o Figure s 10 , 11 , 1 2 an d 13 , thes e value s can b e see n t o approximatel ycorrespond t o the maximu mpurg e rate s evaluated . Theyoccur in the regio n o f th e curve s wher e ther e i s littl e sensitivit yo f caniste r siz e t o purg e rate . They , therefore , do no t appea r t o represen t an yseriou s constrain t o n system design o r th e tradeof f betwee n purg e rat e an d caniste r size . However , a s note d a t the onset , i f i t wer e desirabl e to

_ operat e at highe r purg e rate s than thes e limits , the powe r perturbatio n shoul d no t presen t a seriou s limiting facto r becaus e o f the abilit yt o us e suc htechnique s a s dampe d purg e contro l valves . 5. 3 Caniste r Supplie d Fue l T o thi s point , th e analysi s ha s looked a t onl yon e o f th e two caniste r purg e factor s whic hca n impac t engin e operatio n (i.e. , the amoun t o f ai r coming fromth e canister) . Th e second factor , caniste r supplie d hydrocarbon s whic hbecom e par t o f th e tota l volum e o f fue l supplie d t o th e engine , i s evaluate d here . Thi s analysi s i s performe d b yfirs t examining existin g evaporativ e systems , followe d b yan extrapolatio n t o onboar d systems . 5.3. 1 Presen t Evaporativ e Contro l System s Purging o f hydrocarbon s store d i n evaporativ e emissio n canister s i s presentl ybeing , performe d withou t an excessivel y negativ e effec t on engin e operation . Tes t dat a reporte d b yAP I (Tes t Protoco l fo r Automotiv e Evaporativ e Emissions , AP I Publicatio n No . 4393 ) show s a rang e fo r evaporativ e caniste r purg e ai r rate s froma lo wo f approximatel y3 ft 3 pe r LA- 4 up t o approximatel y1 1 ft 3 pe r LA- 4 fo r the si xGMan d For d vehicle s tested . Combining th e purg e rate s fo r eac hvehicl e wit hthe purg e curv e fo r Ford typ e canister s provide s an estimat e o f th e maximu m mas s o f hydrocarbo n purge d from a full y loaded evaporativ e caniste r during a n LA- 4 (th e For d typ e caniste r characteristi c wa s selecte d becaus e i t exhibit s th e highes t initia l desorptio n rates) . Fo r the si xvehicle s teste d b yAPI , the measure d volume o f ai r purge d pe r LA- 4 an d th e estimate d mas s o f hydrocarbo n purge d fromth e canister , starting wit ha loade d canister , i s show n i n Tabl e 5 . Using th e fue l econom yvalue s measure d fo r eac hvehicl e an d th e assumptio n use d previousl ytha t th e air/fue l rati o i s maintaine d a t 14.7:1 , the mas s o f fue l an d volum e o f ai r consume d b

yeac hvehicl e during a n LA- 4 wer e calculated . Th e measure d volume s o f ai r coming fromth e caniste r an d th e estimate d maximu

mmas s o f hydrocarbo n purge d fro mth e caniste r during a

n LA- 4 wer e the n expresse d a s percentage s o f ai r an d fue l used. . Thes e value s ar e show n i n Tabl e 6 .

-46

-P.4 8

Tabl e 5
Evaporativ e Caniste r Purg e Rate s an d Correspondin g H C

Remova l fo r Si xProductio n Vehicle s

Tes t Vehicl e 198 3 Malib u (carb ) 198 3 Escor t (carb ) 198 1 Omeg a (carb ) 198 3 Fairmont (carb ) 198 4 Omeg a (FI ) 198 4 Escor t (FI ) Measure d Fue l Economyo n LA-4 (mpg ) 17. 5 24. 1 21. 8 17. 3 23. 4 27. 0 the Measure d

Caniste r Purg e Ai r pe r LA- 4 (f t )

8. 5 6. 5 11. 0 7. 5 3. 0 10. 0 Estimate d Maximu mH C Purge d pe r LA- 4 (g) *

27. 0 25. 5 28. 0 26. 5 21. 5 27. 8

Becaus e th e H C purg e o f a caniste r i s ver yhig hwhe n th e caniste r i s full yloade d an d decrease s a s th e caniste r loadin g decreases , maximu mH C purge d durin g a LA-4 driv e occur s whe n th e driv e i s initiate d wit ha full yloade d canister . Dependin g o n th e leve l o f H C store d i n th e caniste r a t th e star t o f a n LA-4 drive , th e H C purge d woul d var yfro mthi s maximu mdow n t o almos t zer o fo r a driv e whic hwa s initiate d wit ha nearl yempt ycanister .

-47

-P.4 9

Tabl e 6 Ai r an d Fue l Coming Fro

mEvaporativ e Caniste r During an LA- 4 for Si xProductio n Vehicle s

Vehicl e 198 3 Malib

u 198 3 Escor t 198 1 Omeg a 198 3 Fairmon t 198 4 Omeg a 198 4 Escor t Tota l Fue l

u s L A e d pe r

- 4 (g) * 121 7 88 4 99 7 123 1 91 0 78 9 Tota l Ai r

used pe r LA- 4 (ft 3 )* * 52 8 38 4 42 4 53 5 39 5 34 3 Pe r

To t Can cent** * o f a l Fue l From iste r pe r LA- 4 2. 2 2. 9 2. 9 5. 0 5. 4 3. 5 Percen t Tota l

Ai r FromCaniste r pe r LA- 4 1. 6 1. 7 2. 6 1. 4 0. 8 2. 9

* Fue l use d i n gram s = (7. 5 miles ) E (MPG ) x(3785. 4 cc/gal ) x(0.7 5 g/c c gasoline) . * * Tota l ai r use d i n f t = (grams fue l used ) x(14.7 ) x (1/453. 6 g/lb ) x13. 4 ft 3 /lb.

- ** * Assuming LA- 4 operatio n start s wit ha caniste r loaded t o breakthrough .

-48

-P.5 0

Becaus e o f the non-linea r shap e o f th e caniste r purg e curve , th e averag e percentag e o f tota l fue l supplie d fromth e evaporativ e caniste r ove r a n LA- 4 doe s no t represen t th e greates t percentag e o f fue l contribute d b ythe canister . Th e larges t fue l contributio n occur s jus t afte r caniste r purging i s initiate d i.e. , during the firs t mil e o r fractio n o f a mil e followin

g initiatio n o f purging . T o investigat e th e maximum * percentag e o_

f fue l contribute d b ythe evaporativ e caniste r o n curren t vehicles , th e compute r mode l wa s use d t o calculat e th e percentag e o f tota l fue l coming fro m the caniste r fo r eac ho f the firs t five mile s o f LA- 4 operation , base d upo n the averag e fue l consumptio n o f the vehicle . Th e result s fro mthi s analysi s ar e show n in Tabl e 7 fo r eac ho f the si xvehicle s analyzed . A s ca n be see n i n Tabl e 7 the percentag e o f tota l engin e fue l supplie d b

yth e evaporativ e canister s start s a t high s o f betwee n 6 an

d 1 6 percen t fo r the firs t mil e o f vehicl e operatio n an

d diminishe s a s th e caniste r purges . Th e percen t o f fue l coming fro m th e caniste r woul d reachzer o whe n th e caniste r i s full ypurged . Th e value s o f 6 t o 1 6 percen t o f tota l engin e fue l supplie d b yth e evaporativ e caniste r ca n b e used a s representativ e value s fo r fue l supplie d b ya caniste r whic hdo no t presentl yproduc e advers e effect s on engin e performance .

* Becaus e o f the transien t spee d characteristi c o f th e LA- 4 and , therefore , transien t engin e loadin g an d correspondin g transien t ai r an

d fue l flowt o the engine , th e term maximu mher e mean s the maximu m average d ove r a par t o f th e LA- 4 an

d no t a maximu

m whic hmayoccu r during shor t term transients . Atransien t maximu mwoul d ten

d t o occu r whe n the ai r an

d fue l flowrate s fromthe caniste r wer e hig h an d th e engin e wa s workin g a t a ligh t load , e.g. , i n th e transitio n perio d fro ma cruis e t o a deceleratio n bu t prio r t o a reductio n i n caniste r supplie d ai r an d fuel . Actua l determinatio n o f suc ha maximu mwoul d requir e continuou s measurement s o f bot hai r an d fue l flow s from th e caniste r an

d throughth e engine' s primaryai r an d fue l suppl ysystems . Fo r thi s analysi s the us e o f mil e b ymil e maximu mvalue s o n th e LA- 4 ar e considere d t o b e acceptabl y accurat e value s fo r comparison s betwee n presen t evaporativ e contro l system s an d onboar d system s becaus e th e onboar d system s ar e projecte d t o operat e relativel y similarl yt o presen t evaporativ e systems .

-49

-P.5 1 Tabl e 7
Percen t Total-Engin e Fue l Coming FromEvaporativ e Canister s During th e Firs t Fiv e Mile s o f Purging

Percen t Tota l Fue l Purge d fro mCaniste r for . eac ho f th e firs t five mile s o f th e LA- 4 Vehicl e 198 3 Malibu 198 3 Escor t 198 1 Omeg a 198 3 Fairmon t 198 4 Omeg a 198 4 Escor t 1s t

Mil e 1 0 1 2 1 4 9 6 1 6 2n

d Mil e 3 4 3 3 4 3 3rd

Mil e 1 2 2 1 3 2 4t h

Mil e 1 1 1 1 2 1 5t h

Mil e 1 1 1 1 1 1

-50

-P.5 2

5.3. 2 Onboar d Contro l Canister s Having identifie d the firs t mil e fue l contribution s from curren t evaporativ e emissio n canisters , th e previousl ysize d onboard refueling canister s wer e similarl yreanalyze d t o determin e thei r firs t mil e fue l contributions . Th e result s fro mthi s reanalysi s ar e show n i n Figure s 1 9 through2 2 a s percen t firs t mil e fue l fro mthe caniste r plotte d agains t percen t engin e ai r coming fro mthe canister . Th e larges t value s fo r percen t firs t mil e fue l (1 6 percent , Tabl e 7 ) an d percen t ai r (2. 9 percent , Tabl e 6 ) fromth e caniste r fo r th e vehicle s reporte d in th e AP I stud yar e als o show

n t o indicat e presen t practice . A s ca n be see n i n Figure s 1 9 through22 , firs t mil e fue l contribution s b

yonboar d canister s a t highe r purg e rate s ca n substantiall yexcee d curren t evaporativ e caniste r firs t mil e fue l contributions . Whil e ther e i s presentl yno dat a t o indicat e th e degre e t o whic hfirs t mil e fue l contribution s coul d increas e beyond presen t evaporativ e caniste r practice , i t appear s reasonabl e t o assume tha t th e larges t value s shown (e.g. , 8 0 t o 9 0 percen t o f engin e full ) coul d caus e operationa l problems . Therefore , caniste r supplie d fue l appear s t o b e a bigge r constrain t tha n doe s purg e ai r flow . Reproduce d i n Figure s 2 3 through2 6 ar e th e caniste r siz e versu s purg e ai r flowrat e tradeof f curve s fo r fue l injecte d system s a s previousl ypresente d a s Figure s 1 0 through13 , wit h informatio n adde d t o indicat e the point s o n thes e curve s corresponding t o variou s percen t firs t mil e fue l values . Indicate d ar e value s o f 1 5 percen t (approximatel ycurren t evaporativ e systempractice) , 2 5 percen t an d 3 5 percent . A s can be see n fromthes e figures , a firs t mil e fue l constrain t woul d limi t the us e o f th e smalles t caniste r highes t purg e ai r flowsystems . Th e actua l impac t o f thi s constrain t woul d depen d o n the degre e t o whic hthe vehicle' s fue l meterin g systemcoul d accommodat e fue l supplie d du e t o caniste r purging . On e possibl e strateg yfor dealing wit hthi s matte r come s fro mthe basi c caniste r purg e characteristics . Referring bac k t o Tabl e 7 , i t ca n b e see n tha t th e percen t o f th e engin e fue l coming from

th e evaporativ e caniste r fall s of f quit e rapidl y afte r th e firs t mil e o f operation . Thi s trend i s simila r fo r onboard systems
- (se e Tabl e 8) . Thus , b ymodulatio n o f th e purg e ai r flowrat e t o reduc e th e flowrat e initiall yan d increas e i t late r i n th e tri p the firs t mil e fue l coul d b e reduce d an

d spread ou t mor e graduall yove r subsequen t miles .

-51

-cm

u iyu> z <
o cc

_ J I U J U l M I u _ U J

U . 10 0 

# %•'FIRS TMIL E FUE LV S % TOTA LAI R FOR D TYP E CANISTE R FIGUR E 1 9

D SMAL LCAR % TOTA LAI R FRO M CANISTE R + AV

G CA R LDT HD V

# % FIRS TMIL E FUE LV S % TOTA LAI R

10 0 9 0 -

D : U l \- (/ > H < O 2 O Q

_ U .

_ l

. ' u i u i i_ ( O J

_ > l U - U J

_ l 2 \- V) cm L

. i ? 8 0 -

7 0 - 6 0 - 5 0 - 4 0 - 3 0 - 2 0 - 1 0 - FOR D TYP E CANISTE R FIGUR E 2 0

D SMAL LCA R % TOTA LAI R FRO M CANISTE R + AVG CA R O LO T HD V

# % FIRSTMIL E FUE LVS % TOTA LAI R

10 0 

### 9 0 -



### cm U l h i/ > z < o

_ > o cm u .

_ J U i—

. 1 la i d

_ > H I/ ) C t U . 

### tf 8 0 -

7 0 - 6 0 - 5 0 - 4 0 - 3 0 - 2 0 - 1 0 NISSA N TYP E CANISTE R FIGUR E 2 1

D SMAL LCA R % TOTA LAI R FRO M CANISTE R + AV

G CA R O LDT HDV

U l U l

# % ' FIRS TMIL E FUE LV S % TOTA LAI R

cm U J

_ 

### z <

o cm u . i - J u iUl U l I D L . U J

u. tf 10 0 NISSA N TYP E CANISTE R FIGUR E 2 2

D SMAL LCA R % TOTA LAI R FRO M CANISTE R + AV

G CAR O LDT HD V

# % FIRS TMIL E FUE LFRO M CANISTE R S M CA R

i U l < ^ I L J N if) 

### cm U J

_ 

### z < 3. 5

3. 4 3. J - 3. 2 - 3. 1 - 3 - 2. 9 - 2. 8 - 2. 7 - 2. 6 - 2. 5 2. 4 H 2. 3 2. 2- 2. 1 - 2- 1. 9 1. 8 H 1. 7 1. 6 H 1. 5 CANISTE R SIZ E V S PURG E AI R FIGUR E 2 3

~T" 8 1 2 1 6 T " 2 0 2 8
FD CA N NI S CA N PURG E AI R PE R LA- 4 (C U FT ) O % FU LF D A % FU LNI S

TJ b iI

U l V J I U J N </ > cm u i i - (/ > 

### z < 

# % FIRSTMIL E FUE LFRO M CANISTE R AVCA R CANISTE R SIZ E VS PURG E AI R FIGUR E 2 4

8 -

7 -

6 -

5 -

4 -

3 -

0 15 %

F D CA N NI S CA N ri 2 0 PURG E AI R PE R LA- 4 (C U FT)

O %EU LF D 4 0 FOR D

3 5 % NISSA N

6 0

_ _% FU LNI SI

U l o o I U l 

### N if) cm u i h if) 

### z < 

# % FIRS TMIL E FUE LFRO M CANISTE R LD T CANISTE R SIZ E V S PURG E AJR FIGUR E 2 5

10 0
F D CA N PURG E AI R PE R LA- 4 (C U FT) NI S CA N O % F.U LF D % FU LNI SI

U l I U l N If) cm u i h -

_ 2 z < 6 0

5 0 -

4 0 -

3 0

2 0 -

1 0 -

0 

# % FIRS TMIL E FUE LFRO M CANISTE R HD V CANISTE R SIZ E V S PURG E AI R FIGUR E 2 6

20 0
F D CA N PURG E AI R PE R LA- 4 (C U FT) NI S CA N O % FU LF D % FU LNI SP.6 1

Vehicl e Smal l Ca r (2.41 ; 9 ft 3 )N * 1s t Mil e 2 1 2n

d Mil e 1 6 Tabl e 8
Percen t Tot-al Engin e Fue l Coming FromTypica l Onboar d Canister s During the Firs t Fiv e Mile s o f Driving
Percen t Tota l Fue l Purge d FromCaniste r fo r Eac ho f the Firs t Fiv e Mile s o f th e LA- 4 3rd 4t h5t h Mil e Mil e Mil e 1 2 8 7
Smal l Ca r 4 0 2 8 1 7 9 5 (2.651 ; 9 ft 3 ) F Averag e Ca r 2 7 1 1 9 8 7 (3.01 ; 3 0 ft 3 ) N Averag e Ca r 2 3 1 7 1 5 1 0 7 (4.61 ; 1 0 ft 3 ) F LD T 1 4 1 3 1 2 1 1 1 0 (201 ; 2 0 ft 3 ) N LD T 2 6 2 4 2 1 2 0 1 5 (151 ; 2 0 ft 3 ) F HDG V 1 6 1 4 1 4 1 2 1 2 (52.51 ; 5 0 ft 3 ) N HDG V 3 1 2 8 2 1 2 1 1 9 (32.31 ; 5 0 ft 3 ) F

* Siz e o f caniste r i n liters , purg e ai r flowrat e i n ft 3 /LA-4 , N= Nissa n type , F = For d type. .

-60

-6 . Summary

Prio r t o proceeding wit hth e sectio n o f th e analysi s whic h addresse s tes t procedur e revisions , i t i s appropriat e t o summariz e th e keyfinding s o f the analysi s t o thi s poin t a s the yrelat e t o vehicl e conditioning fo r refuelin g measurements . Th e analysi s o f caniste r an d vehicl e operationa l characteristic s ha s shown :
° Tha t the leve l o f hydrocarbo n store d i n the caniste r whe n the vehicl e i s operate d unde r repetitiv e cycli c drive , ho t soak an d diurna l condition s reache s stabilizatio n afte r a t mos t a fewday s o f operation . ° Tha t th e caniste r stabilizatio n leve l i s highl ydependen t upo n the operating patter n o f the vehicl e an d o n th e amoun t o f purg e whic hoccur s wit heac hdriv e an d th e amoun t o f loading whic hoccur s wit heac hho t soa k an d diurnal . ° That , fo r continuou s driving wit hno ho t soa k o r diurna l emissions , the caniste r wil l be rapidl ypurge d t o a ver y lo wlevel . ° That , fo r give n ho t soak an d diurna l loadings , appropriat e selectio n o f caniste r siz e an d purg e ai r flowrat e wil l provid e adequat e storag e capacit yfor refueling vapor s a t the stabilize d caniste r loading . ° Tha t a rang e o f caniste r siz e an d purg e ai r flo wrat e choice s ar e availabl e for an ygive n vehicl e whic hshoul d no t adversel yaffec t vehicl e performance . ° Tha t whil e require d caniste r siz e i s inversel y proportiona l t o purg e ai r flowrate , th e relationshi p i s no t linear . 7 . Tes t Procedur e Revisio n 7. 1 Evaluatio n o f Preconditioning i n Draf t Procedur e Th e preceding analysi s ha s identifie d ho wahonboar d caniste r woul d b e expecte d t o purg e an d load during typica l in-us e operatio n an d ha s provide d a metho d fo r modelin g thi s operation . Acompariso n o f th e effect s o n caniste r purging du e eithe r t o th e 5 0 mil e continuou s driv e o r th e 3 0 percen t drive-dow

n step s propose d i n th e origina l draf t procedur e wit h a representativ e onboar d caniste r performanc e curv e i s show n i n Figur e 27 . A s ca n b e seen , bot hth e 5 0 mil e driv e an d th e 3 0

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# CANISTE R PURG E - THRE E DRIV E TYPE S FIGUR E 2 7

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_ Q > - I 16 0

15 0 14 0 13 0 12 0 11 0 10 0 9 0 8 0 7 0 6 0 5 0
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THRE E TRIP S MILE S DRIVE N 3 0 % TAN K 5 0 MIL EP.6 4

percen t drive-dow

n purg e the caniste r wel l beyond expecte d in-us e levels . Thes e procedure s would , therefore , produc e non-representativ e caniste r purge s an d woul d no t b e appropriat e for caniste r conditioning prio r t o th e measuremen t o f refueling emissions . I t i s als o apparen t fro mth e modeling wor k tha t caniste r purg e an

d refueling capacit yar e no t separabl e items , an d tha t the approac huse d i n th e origina l draf t procedur e o f evaluatin g eac haspec t wit ha separat e tes t i s inappropriate . Th e actua l storag e capacit ywhic hthe vehicl e wil l hav e availabl e upo n refuelin

g i s a functio n o f th e caniste r purg e rat e an d th e vehicl e driving , patter n a s wel l a s o f th e caniste r size . Becaus e o f this , th e performanc e o f th e entir e refueling syste m can b e evaluate d wit ha singl e tes t whic hfirs t precondition s the caniste r t o a leve l nea r it s equilibriu mleve l an

d the n perform s th e refueling operation . Thi s greatl yreduce s th e overal l complexit yo f the refueling tes t an d it s resourc e impact s an

d als o allow s i t t o b e separate d from th e testin g fo r exhaus t an

d evaporativ e emissions . Th e following sectio n develop s th e preconditioning procedure s neede d fo r th e revise d test . 7 . 2 Revise d Caniste r Conditioning Base d upo n the modeling whic hha s bee n done , ther e ar e tw o option s fo r simulating in-us e performance . Th e firs t i s a cycli c drive-dow

n o f alternating drive s an d soak s directl y simulating a few"days " o f vehicl e operatio n t o approximatel y establis hthe caniste r equilibriu mlevel . Th e second i s a short , continuous , drive-dow n t o th e equilibriu mleve l wit hn o soak periods . Reproductio n i n the laboratoryo f th e cycli c in-us e dail y operating patter n woul d b e accomplishe d b yth e repetitiv e performanc e o f a simulate d dail ypatter n consistin g o f thre e LA-4s , eac hseparate d b ya on e hou r ho t soa k plu s th e performanc e o f a diurna l hea t buil d following th e las t ho t soak . Thi s "daily " caniste r conditioning sequenc e woul d constitut e the basi c building bloc k fo r the constructio n o f th e caniste r conditioning phas e o f the onboar d tes t procedure . Sequentia l repetition s o f thi s basi c sequenc e unti l th e caniste r stabilizatio n leve l wa s reache d (or approximated , i n the cas e o f a caniste r systemrequiring a n unusuall ylon

g time t o completel ystabilize ) woul d constitut e th e primar yprocedur e whereb ycanister s woul d be conditione d prio r t o measuremen t o f refueling emissions . Ther e ar e severa l thing s t o not e abou t thi s approach . First , i t shoul d accuratel ysimulat e a realisti c conditionin g sequence . O f course , a s note d i n the earlie r discussio n o f th e

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effect s o f driving patterns , in-us e pattern s o f les s tha n thre e trips , pe r da

ywoul d purg e les s than woul d thi s procedure . However , ther e ar e compensating condition s o f tes t conditio n stringencywhic hac t t o offse t thi s difficulty . Secondly , i t appear s tha t nearl yal l vehicle s wil l reac hequilibriu mwithi n thre e t o fiv e "days " o f simulate d operation . I n fact , afte r onl ythre e "days" , al l vehicle s appea r t o be withi n a t mos t a fe wgram s o_

f equilibrium . Therefore , thre e simulate d day s shoul d provid e adequat e caniste r conditioning . This , o f course , mean s tha t conditioning ca n be performe d wit h substantiall yfewe r testing resource s than th e originall y propose d 3 0 percen t drive-down . Third , becaus e o f the rapi d rat e o f purg e whe n the caniste r i s full yloaded , thi s conditioning sequenc e i s relativel yinsensitiv e t o th e initia l startin g conditio n o f the canister . Th e initia l ' perio d o f caniste r purging t o a leve l nea r th e equilibriu mleve l occur s withi n the firs t doze n or s o driving miles , s o th e tota l tim e t o reachstabilizatio n i s no t significantl yaffecte d b yth e initia l loading o n th e canister . Whil e greatl yreducing resourc e impact s fromthe origina l draf t procedure , multipl e repetition s o f the "daily " operating sequenc e wil l stil l be somewha t time an d facilit yintensive . Remembering tha t continuou s vehicl e driving (i.e. , n o ho t soak s or diurnals ) wil l resul t i n rapi d purging o f th e canister , EPA investigate d thi s approac ha s anothe r alternativ e fo r caniste r conditioning . Th e compute r mode l wa s use d t o determin e th e numbe r o f continuou s LA- 4 mile s require d t o achiev e caniste r purging equivalen t t o the cycli c driv e stabilizatio n level . Th e result s o f thi s evaluation , plotte d a s continuou s LA- 4 mile s versu s purg e ai r flowrate , ar e show n in Figure s 2 8 through3 1 fo r th e system s previousl yevaluated . A s ca n b e see n fromthes e figures , th e numbe r o f continuou s LA- 4 mile s require d t o reac hthe caniste r stabilizatio n leve l i s unde r 2 0 mile s i n mos t cases , although i t goe s a s higha s 3 3 mile s fo r heavy-dut yvehicle s wit hver y lo wpurg e rates . Relativ e t o the "daily " cycli c driv e conditioning procedure , th e continuou s driv e procedur e woul d provid e significan t saving s i n bot htime an d facilities . A s envisione d fo r th e tes t procedure , th e continuou s driv e woul d operat e a s follows . Following caniste r loading , th e vehicl e woul d be drive n continuousl yove r repetitiv e LA- 4 cycle s unti l th e stabilize d leve l wa s reached . I n th e cas e o f a partia l cycl e neede d t o complet e th e require d mileage , th e vehicl e woul d b e stoppe d a t th e firs t idl e poin t afte r reaching the desire d mileage . Th e refueling tes t woul d the n b e performed . Th e numbe r o f mile s t o b e drive n woul d be base d upo n previou s testing t o establis hequivalenc e wit hth e cycli c

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# CONTINUOU S DRIV E MILE S FO R PURG E FOR D TYP E CANISTE R F l FIGUR E 2 8

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# CONTINUOU S DRIV E MILE S FO R PURG E FOR D TYP E CANISTE R CARB

. FIGUR E 2 9

SMAL LCA R PURG E AI R PE R LA- 4 (C U FT) + AV

G CA R O LDT 14 0 HDVI

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# CONTINUOU S DRIV E MILE S FO R PURG E NISSA N TYP E CANISTE R F l FIGUR E 3 0

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# CONTINUOU S DRIV E MILE S FO R PURG E

C3S CX) I Z U l > 

### cm c . in UJ NISSA N TYP E CANISTE R CARB

. FIGUR E 3 1

SMAL LCA R PURG E AI R PE R LA- 4 (C U FT) + AV

G CA R O LDT HD Vdrive . Based , a s i t woul d be , upo n th e purg e leve l develope d

b ythe cycli c drive , thi s tes t woul d no t be a full yindependen t operation . Rather , i t woul d b e a n abbreviate d approac ht o obtaining th e same result s a s the cycli c drive . I t coul d b e use d b ymanufacturer s i n repeate d testing o f th e sam e o r substantiall ysimila r vehicles , an d b yEPAi n al l phase s o f it s testing . Th e continuou s driv e wil l allowcaniste r conditionin g wit h a greatl yabbreviate d procedure . Becaus e o f this , i t woul d likel yserv e a s the principa l approac huse d b yEPA . Manufacturers , onc e theyhad initiall yconducte d th e cycli c tes t i n orde r t o develop th e appropriat e continuou s driv e mileage , woul d als o be abl e t o us e the continuou s driv e cycl e for subsequen t repetitiv e work . Th e continuou s driv e procedur e shoul d giv e equivalen t result s t o th e cycli c drive . O n the othe r hand , the continuou s driv e procedur e ha s th e limitatio n tha t i t doe s no t itsel f physicall ydemonstrat e tha t the contro l systemha s the abilit yt o actuall ypurg e ho t soa k an d diurna l loads . Thus , i n spit e o f it s advantage s i n term s o f resourc e impacts , the continuou s driv e canno t be th e onl y preconditioning sequence . However , s o lon g a s the cycli c drive-dow

n i s als o retained , EPAwoul d i n al l likelihoo d b e abl e t o us e the continuou s drive-dow n fo r th e bul k o f it s testing . Th e longe r cycli c procedur e woul d b e reserve d fo r thos e case s whe n the Agenc yfel t the nee d t o full ydemonstrat e systemperformanc e vi a direc t testing . Overal l then , th e revised refueling procedur e wil l specif ybot hpreconditionin g sequence s wit hthe requiremen t tha t an yvehicl e b e abl e t o pas s the tes t regardles s o f whic hi s used . 7. 3 Conditioning o f Non-Integrate d Contro l System s Throughou t th e preceding analysis , th e us e o f full y integrate d refueling an d evaporativ e emissio n control s ha s bee n assumed . Tha t is , the analysi s ha s presume d tha t th e same caniste r i s use d t o collec t an d stor e ho t soak , diurna l an d refueling emissions* . Sinc e manufacturer s mayelec t t o us e on e caniste r dedicate d t o the collectio n an d storag e o f refueling vapor s alon e an

d anothe r caniste r fo r ho t soa k an d diurna l emissions , conditioning o f thes e canister s .wil l b e addresse d a t thi s time . Th e preceding analysi s i s als o applicabl e t o system s wherei n th e refueling caniste r i s use d t o collec t eithe r ho t soak o r diurna l emission s (i.e. , partiall yintegrate d sytems) .

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Sinc e the refueling caniste r i n a non-integrate d syste m ma yno t experienc e ho t soak o r diurna l loadings , purging woul d be the same whethe r the vehicl e wa s drive n continuousl yo r unde r cycli c conditions . Suc ha systemwoul d als o no t b e expecte d t o come t o a n equilibriu

mconditio n sinc e eac hdriv e woul d continu e the proces s o f purging the caniste r t o lowe r an d lower levels . Thus , the onl ywayt o full ysimulat e condition s o f a nearl y.empt

yfue l tank woul d b e t o actuall ydriv e ou t th e required amoun t o f fuel , beginning wit ha loade d caniste r an d a ful l fue l tank . Sinc e the refueling emission s measuremen t i s initiate d fro

m the 1 0 percen t tank volume leve l an d fueling i s continue d unti l the fue l leve l i n the tan k i s a t leas t 9 5 percen t o f tan

k volume , th e continuou s driv e duratio n fo r non-integrate d system s woul d hav e t o b e th e mileag e corresponding t o the consumptio n o f fue l equa l t o 8 5 percen t o f fue l tank volume . Aful l drive-dow

n for non-integrate d system s woul d b e a tim e an d resourc e intensiv e process . I n addition , give n th e non-linea r natur e o f th e purg e proces s (refe r t o th e caniste r purg e curve s give n i n Figur e 3 ) mos t o f th e purg e woul d actuall yb e accomplishe d i n the initia l phase s o f th e drive-down . A

n alternativ e procedure , therefor e migh t b e a partia l drive-dow

n o f perhap s 3 0 t o 4 0 percen t o f tank volum e followe d b

ya nearl yful l refueling . Sinc e thi s procedur e woul d no t directl yverif yful l systemperformance , i t woul d have t o remai n a s a n optiona l test , simila r t o th e shor t continuou s driv e fo r integrate d systems . I t migh t als o b e couple d wit hsupporting tes t dat a o r engineerin g analysi s t o demonstrat e tha t satisfactoryperformanc e a t th e intermediat e leve l woul d b e expecte d t o resul t i n ful l performanc e o n a ful l test . Th e potentia l us e o f thi s optio n ha s no t ye t bee n analyze d i n detai l t o determin e adequat e driv e mile s and fil l amounts . Suc ha

n analysi s i s planne d fo r th e future . F . Miscellaneou s Issue s I n additio n t o the comment s addresse d above , comment s wer e provide d o n severa l othe r area s o f th e recommende d tes t procedure . Thes e area s include d th e baselin e refueling emissio n factor , provision s fo r retests , vehicl e temperatur e prio r t o the refueling test , specification s fo r refuelin g nozzles , an

d numerou s othe r mino r comments. * Th e Californi a Ai r Resource s Boar d (CARB ) too k issu e wit h the baselin e refueling emissio n factor . CAR B state d tha t dat a collecte d i n Californi a fromrefueling s o f in-us e vehicl e a t servic e station s showe d refueling emissio n factor s o f 3. 7 g/gallo n wit h8. 0 RVP summe r fue l an d 5. 6 g/gallo n wit h12. 0 RVP winte r fue l fo r an averag e o f 4. 5 g/gallon . CAR B wen t o n t o stat e tha t a nationa l refueling contro l program shoul d b e base d o n th e Californi a annua l averag e valu e o f 4. 5 g/gallo n

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rathe r than the 5. 9 g/gallo n valu e use d b yEPAfo r 12. 6 RV P summe r refuelings . Th e purpos e o f thi s approac hwa s t o achiev e a lowe r refueling emissio n standar d unde r a fixe d percen t reductio n approach . EPAdoe s no t agre e wit hCARB' s analysis . First , EPAdoe s no t believ e tha t i t can equat e refueling emission s measure d a t servic e station s unde r unknow n measuremen t condition s t o emission s measure d unde r controlle d laborator ycondition s suc h a s ar e include d i n the draf t procedur e an d describe d i n EPA' s report , "Refueling Emission s fromUncontrolle d Vehicles. " Thi s repor t detail s EPA' s baselin e progra mt o measur e refueling emission s an

d EPAwil l continu e t o us e the baselin e refueling emissio n facto r resulting fro mit s baselin e program . Second , the CARB commen t appear s t o focu s o n achieving th e lowes t possibl e numerica l emissio n standar d associate d wit ha 9 5 percen t reductio n o f baselin e emissions . Th e EP Astandar d i s no t intende d t o b e a simpl e percen t reductio n o f th e baselin e refueling emissions . Th e refueling standard wil l b e chose n t o be a measurabl e an d reasonabl e leve l a s nea r t o zer o emission s a s i s possible . Thus , a chang e i n th e baselin e emissio n leve l woul d no t automaticall yresul t i n a chang e i n the standard . In commenting o n the nee d for retests , MVM Astate d tha t the recommende d procedur e di d no t provid e a clearl y identifiabl e rout e for the performanc e o f a retes t o f on e segment , e.g. , tailpip e emission s measurement , o f th e overal l procedur e eithe r becaus e o f a tes t voi d o r a failur e i n on e segmen t o f the test . Aclea r lin e o f demarcatio n betwee n th e refueling segmen t an d othe r segment s o f the overal l procedur e wa s requested . Th e draf t tes t procedur e repor t discusse d provision s t o reru n test s i f needed . Fo r the refueling tests , ther e wer e severa l appropriat e place s identifie d wher e partia l testin g coul d be restarte d t o avoi d having t o reru n the entir e sequenc e i n cas e o f a tes t voi d i n on e segmen t o f the test . Th e revise d refueling procedur e i s nowcompletel yseparabl e fromth e exhaus t an

d evaporativ e tes t procedures , providing th e clea r line o f demarcatio n requeste d b yMVMA . I n th e even t tha t a retes t o f the evaporativ e o r exhaus t tes t wer e t o b e required , th e retes t woul d b e initiate d a t the first.ste p i n th e vehicl e preparatio n procedur e wit hth e requiremen t t o re-loa d th e canister(s ) prio r t o th e 4 0 percen t fueling fo r th e pre p LA- 4 preceding the col d soak . Aconcer n regarding the tes t vehicle' s temperatur e prio r t o the refueling tes t wa s note d b yToyota . T o preclud e inclusio n o f evaporativ e emission s int o th e refueling emissio n measurement , Toyot a recommende d tha t th e tes t vehicl e b e coole d t o soak are a temperatur e prio r t o performing th e refueling emissio n measuremen t test . Thi s i s a vali d point , an d i n

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-respons e the procedur e wil l b e modifie d t o includ e th e

stabilizatio n o f th e vehicl e temperatur e a t th e soa k are a temperature . Thi s wil l be achieve d b ysoaking th e vehicle , followin

g the preconditioning o f the canister , fo r a minimumo f 6 hour s an

d a maximu

mo f 2 4 hours . Tw o commenter s state d tha t a specificatio n wa s neede d fo r the accuracy , o f the dispense d fue l meter . EPAagree s wit h thes e comment s an

d i s including a dispense d fue l mete r accurac y specificatio n i n th e revise d procedure . I n additio n t o comment s abou t limitin g the dispense d fue l flowrat e reviewe d earlie r i n Sectio n I I A , a numbe r o f manufacturer s commente d o n th e nee d t o contro l refueling nozzl e specifications . Thes e applie d t o bot hin-us e an d tes t nozzles , i n area s o f the nozzl e whic hcoul d impac t th e effectivenes s o f onboard control . Example s o f the area s o f nozzl e desig n whic h coul d b e considere d fo r standardizatio n unde r a unifor m specificatio n focu s o n th e nozzl e spou t an d includ e length , angl e o f ben

d i n th e spou t an

d it s locatio n along th e lengt ho f the spout , an

d positio n o f the automati c shut-of f port . Presentl yther e ar e no standardize d specification s applicabl e t o thes e area s o f the nozzle . EPAi s concerne d abou t the impac t tha t nozzl e geometr ymay have o n refueling emissions , bu t ha s littl e dat a a t presen t wit hwhic ht o evaluat e thes e claims . I f i t wer e tru e tha t nozzl e geometrycoul d substantiall yaffec t the performanc e o f refueling systems , the n a standardize d desig n migh t b e considered . I f thi s wer e th e case , suc hstandardizatio n woul d have t o b e applie d bot ht o tes t equipmen t an d t o in-us e nozzles . Otherwise , refueling systemperformanc e woul d suffe r i n practice . Lacking detaile d information , no decisio n ca n b e mad e o n thi s issu e a t present . Th e submissio n o f tes t dat a demonstrating the degre e o f sensitivit yinvolve d woul d b e especiall yuseful . I t woul d als o be necessaryt o determin e t o wha t degre e fil l nec k design s coul d b e modifie d t o accep t greate r nozzl e variability . Finally , numerou s mino r comment s wer e provided . Example s o f thes e mino r comment s includ e recommendation s fo r th e expansio n o f th e toleranc e band s fo r th e ho t soa k time s and th e drive r trac e during th e caniste r conditionin g driv e t o facilitat e testing an d t o avoi d unnecessarytes t voids . Thes e type s o f comment s ar e addresse d b ymino r changes , wher e appropriate , i n th e tes t procedure .

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III . Tes t Procedur e Overvie wSummary A . Onboar d Tes t Procedur e Th e onboar d refueling emissio n tes t procedure , resulting fro mthe preceding reanalysi s woul d consis t o f four basi c steps . I n the firs t step , th e onboar d caniste r woul d b e loade d t o a t leas t .breakthrough . Th e second step i n th e procedur e woul d be caniste r purging t o the appropriat e leve l b ymean s o f the applicabl e vehicl e drive . Th e third step woul d b e vehicl e coo l dow

n t o ambien t temperatur e followe d b yth e fourt hste p wherei n the refueling emission s ar e measured . Th e detail s o f the task s performe d withi n eac ho f thes e step s ar e shown i n Figur e 32 . Briefly , th e executio n o f th e procedur e a s show n i n Figur e 3 2 woul d be a s follows . I n the caniste r loading t o breakthroughstep , th e vehicle , i n as-receive d condition , i s brough t int o th e laboratoryan d the fue l tank i s drained . Th e vehicl e i s soake d fo r si xhour s i n th e laboratoryt o bring th e temperatur e o f th e vehicl e int o equilibriu mwit hth e laboratory ambien t temperature . Following temperatur e equilibration , th e vehicl e i s move d int o the SHE D an d fue l i s adde d t o th e fue l tan k unti l caniste r breakthroughi s detected . I n thos e case s wher e the caniste r loadin g i s alread

ya t o r beyond breakthroug h in the as-receive d conditio n (sucha s migh t occu r durin g testing o f in-us e vehicles) , th e analyze r respons e t o hydrocarbon s emanating fro mth e caniste r woul d closel ycoincid e wit hthe initiatio n o f fueling an d littl e fue l woul d hav e t o b e added t o the fue l tank for the purpos e o f loadin g the canister . Upo n completio n o f th e caniste r loading step o f th e procedure , the vehicl e wil l ente r int o th e caniste r purg e step . I n the caniste r purg e step , th e procedur e whic hwil l b e followe d wil l depend , first , o n whethe r th e vehicl e i s equippe d wit han integrate d o r a non-integrate d emissio n contro l syste m an d second , i f an integrate d system i s employed , whethe r th e cycli c driv e procedur e o r the continuou s driv e procedur e ha s bee n selected . I n Figur e 32 , th e block s heade d "Integrate d SystemCaniste r Purge , Cycli c Drive " an d "Integrate d Syste m Caniste r Purge , Continuou s Drive " ar e applicabl e t o integrate d system s an

d specif ythe detail s o f the step s i heac ho f thes e purg e procedures . Th e bloc k heade d "Non-integrate d Syste m Caniste r Purge , Continuou s Drive " specifie s th e detail s o f th e purg e procedur e fo r non-integrate d systems . I n eac ho f the purg e procedures , the firs t step s ar e th e same , i.e. , t o disconnec t the caniste r vapo r lin e t o avoi d disturbing th e caniste r loading , t o drai n th e fue l tank , t o fue l wit hth e specifie d volume o f fue l (4 0 percen t fo r

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-

# £

IntegratedSyste

m Caniste r Purge , Cycli c Drive
a . Disconnec t Vapo r Lin e t o Caniste r b . Drai nFue l Tan k c . 40 % Fuelin

g d . Reconnec t Vapo r Lini e t o Caniste r e . Driv e One LA- 4 f . On e Hour Ho t Soa k g . Repea t (e ) an

d(f ) Twic e h . Disconnec t Vapo r Lin e t o Caniste r 1 . Drai nFue l Tank j . 40 % Fueling k . Reconnec t Vapo r Lin e t o Caniste r 1 . Hea t Buil d(60 ° + 2° F Initial , 2 4 + 1° F Rise ) m . Repea t (e ) Through(1 ) Twic e n . Driv e One LA- 4

i i Caniste r Loading to Breakthrough ° Drai nFue l Tan

k ° Soa kVehicl e for 6 Hour s ° Fue l inSHE Dt o Breakthrough 

# I Integrate dSyste

m Caniste r Purge , Continuou s Drive
a . Disconnec t Vapo r Line t o Caniste r b . Drai nFue l Tank c . 40 % Fueling d . Reconnec t Vapo r Line t o Caniste r e . Drive Repeate dLA-4 s Unti l Mileag e Accumulate d= Mileag e Require dfo r Purg e Equivalen t t o Cycli c Drive . Mileag e AccumulationStop s a t the Firs t Idl e Pas t th e Mileag e Requiremen t 

# 1 Non-integrate dSyste m Caniste r Purge , Continuou s Drive
a . Disconnec t Vapo r Lin e t o Caniste r b . Drai nFue l Tan k c . 95 % Fueling d . Reconnec t Vapo r Lin e t o Caniste r e . Drive Repeate dLA-4 s Unti l 85 % o f TankVolum

e I s Consumed

Vehicl e Coo l Dow

n Disconnec t Line t o Caniste r Drai nFue l Tank 10 % Fueling Soa kVehicl e 6 t o 2 4 Hour s 

# I Refueling Emission s Measuremen t Reconnec t Vapo r Line t o Caniste r Fue l t o Automati c Nozzl e Shut-of f (85 % MimimunFueling) . Restar t Fueling Following An

y Prematur e Shut-off s Withi n 1 5 Seconds )

ONBOARDTES T PROCEDURE FLO W CHAR T 

### FIGUR E 3 2integrate d system s an d 9 5 percen t fo r non-integrate d systems ) an d finall yt o reconnec t the caniste r vapo r line . Fo r non-integrate d system s actua l purging o f th e caniste r wil l consis t o f driving th e vehicle , using repetition s o f th e LA- 4 cycle , unti l 8 5 percen t o f tank volume ha s bee n consumed . Fo r integrate d systems , actua l purging o f the caniste r wil l b e performe d eithe r b ya shor t continuou s driv e using repetition s o f the LA- 4 .unti l th e caniste r i s purge d t o th e leve l equa l t o tha t achieve d wit hthe cycli c driv e o r b yth e cycli c driv e procedure . I n the cycli c driv e procedure , the LA- 4 i s performe d thre e time s wit heac hperformanc e o f th e LA- 4 being followe d b

ya on e hour ho t soak . Following completio n o f th e third LA-4/ho t soak , the caniste r vapo r lin e i s disconnected , the fue l tank i s draine d an d fuele d t o 4 0 percen t wit hchille d fuel , th e vapo r lin e i s reconnecte d an d a diurna l hea t buil d i s performed . Th e thre e LA-4 , thre e ho t soak s an d on e diurna l hea t buil d cycl e i s repeate d twic e an d i s followe d b

yth e performanc e o f on e LA-4 . A t thi s point , th e caniste r purg e drive s hav e bee n complete d an d th e vehicl e enter s th e coo l down step o f th e procedure . I n th e coo l dow

n step , the vapo r lin e i s disconnecte d t o ensur e tha t caniste r loadin g i s no t disturbed , th e fue l tank i s draine d an

d fuele d wit h1 0 percen t fue l an d th e vehicl e i s allowe d t o coo l t o laboratorytemperatur e fo r 6 t o 2 4 hours . Measuremen t o f refueling emission s i s th e fina l step o f the procedur e an

d follow s th e coo l dow n step . I n th e refueling emission s measuremen t step , the vapo r lin e i s reconnecte d an d the vehicl e i s place d i n th e SHED . Th e SHE D i s seale d an d a n initia l measuremen t o f the hydrocarbo n leve l i n th e SHE D i s made . Th e vehicl e i s fuele d i n the SHE D wit ha t leas t 8 5 percen t o f the tank volume o f fuel . Th e fina l hydrocarbo n leve l in th e SHE D i s measured . Th e 8 5 percen t fueling an d th e fina l hydrocarbo n measuremen t ar e the las t two step s i n th e refueling tes t procedure . B . Associate d Change s t o Presen t Tes t Procedure s Existing tes t procedure s fo r the measuremen t o f evaporativ e an

d exhaus t emission s wer e develope d prio r t o an y consideratio n o f onboar d refueling controls . Sinc e thes e procedure s (evaporativ e an d exhaus t test s fo r LDV s an d LDT s an

d evaporativ e test s fo r HDGVs ) includ e two fort ypercen t tank volume fuelings , change s t o accoun t fo r the effect s o f onboar d control s ar e necessaryt o achiev e continuit yi n th e result s o f thes e tests . Th e necessarychange s ar e th e disconnectin g o f the fue l tank t o caniste r vapo r line s prio r t o eac hfue l tank drai n an

d fort ypercen t fueling even t an d th e reconnecting o f th e line s following eac hfort ypercen t fueling . Thes e

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-P.7 7

disconnecting an

d reconnecting event s wil l ensur e tha t ne w an d non-representativ e caniste r loading s ar e no t incorporate d int o existing tes t procedures . Specifically , withi n th e tes t procedure , disconnecting th e vapo r line s woul d occu r firs t whe n the tes t vehicl e enter s a tes t progra man d residua l fue l i s t o b e draine d an

d th e firs t fort ypercen t fueling i s performe d prio r t o the preconditioning driv e an d col d soak an

d second immediatel y.prior t o th e secon d fue l tank drai n an d fuelin g wit hchille d fue l i n preparatio n for the hea t build . I n additio n t o th e previousl yindicate d change s thre e othe r change s t o existing tes t procedure s ar e proposed . Th e firs t o f thes e change s i s the additio n o f tw o step s a t th e start of al l testing o n vehicle s undergoing evaporativ e and/o r exhaus t emission s testing . Thes e two step s ar e a fue l tank drai n an

d a six-hou r vehicl e temperatur e equilibratio n soa k a t a roo mtemperatur e o f betwee n 68° F an d 86°F . Th e second o f thes e change s i s th e requiremen t tha t al l canister s b e loade d t o a t leas t breakthroughprio r t o the performanc e o f th e preconditioning driv e fo r LD V an d LD T evaporativ e an d exhaus t emission s test s an d prio r t o the preconditioning driv e fo r HD V evaporativ e emission s tests . Th e third chang e i s th e requiremen t tha t al l applicabl e canister s be installe d an d operationa l during the performanc e o f HDG E exhaus t emissio n testing . Prio r t o bein g instate d o n th e HDG E undergoin g testing , the canister s ar e require d t o be loaded wit h hydrocarbon s t o a leve l equa l t o tha t existing a t the end o f the diurna l hea t buil d in the HDG V evaporativ e emissio n tes t procedure ; i.e . th e loading resulting froma loading t o breakthrough , followe d b ya vehicl e preconditioning drive , followe d b

ya vehicl e col d soak an d finall yfollowe d b ya diurna l hea t build. .

-76

-P.7 8

Appendi x Evaluatio n o f th e Purg e Respons e Characteristic s

o f Activate d Carbo n Canister s

-77

-P.7 9

I . Introductio n EPAi s currentl yi n the proces s o f developing a procedur e t o tes t the performanc e o f refueling emissio n contro l systems . Regardles s o f th e specific s o f the procedure , i t mus t evaluate ; 1 ) the hydrocarbo n storag e capacit yo f the systeman d 2 ) th e abilityo f the systemt o restor e tha t capacit ybetwee n refuelings . .Testin g the hydrocarbo n storag e capacit yo f th e systemi s relativel ystraightforward , bu t testing the abilit y o f a systemt o restor e tha t capacit yi s significantl ymor e complex . Th e standar d hydrocarbo n storag e mediu m use d i n today' s evaporativ e emissio n contro l system s i s activate d carbon , an d i t appear s likel ytha t activate d carbo n woul d b e use d fo r refuelin

g emissio n contro l a s well . Th e Draf t Recommende d Tes t Procedur e fo r th e Measuremen t o f Refueling Emission s publishe d in Jul y198 5 wa s develope d wit hlimite d detaile d informatio n abou t the purg e characteristic s o f activate d carbo n beds.[2 ] Th e tes t o f purg e capacit ywa s develope d aroun d a genera l knowledg e o f the stripping characteristic s o f activate d carbo n beds , i.e . tha t fo r a give n purg e ai r flow , th e rat e a t whic h hydrocarbon s ar e strippe d f.ro mthe carbo n be d i s highwhe n th e bed i s heavil yloaded wit hhydrocarbon s an d thi s rat e decrease s a s the hydrocarbo n loa d i s reduced . Sinc e it s publication , th e propose d procedur e ha s bee n furthe r analyzed . Thi s analysi s ha s lea d EPAt o the conclusio n tha t the procedur e a s originall y propose d woul d no t adequatel ytes t contro l systempurg e capability . I n orde r t o develop a procedur e whic hdoe s evaluat e the purg e capabilit yo f the contro l system , a bette r understanding o f the desorptio n characteristic s o f activate d carbo n wa s needed . Th e tes t progra mdescribe d i n thi s appendi x wa s undertake n fo r thi s purpose . Th e rat e at whic hhydrocarbon s ar e strippe d from " a n activate d carbo n caniste r i s influence d b ysevera l variables . Some o f thes e ar e associate d wit hth e caniste r desig n an d include ; 1 ) size , 2 ) shape , 3 ) carbo n bas e (the materia l from whic hthe carbo n i s produced ) an d 4 ) interna l configuratio n (ho wth e vapor s ar e route d throughth e carbo n bed) . Othe r variables , suc ha s purg e ai r flowrat e an d purg e temperatur e ar e relate d t o the purg e process . Th e mai n bod yo f thi s tes t progra maddresse d th e canister-relate d variable s b yevaluating the purg e characteristic s o f severa l canister s o f differen t sizes , designs , etc . Althoughno attemp t wa s mad e t o isolat e th e impac t tha t individua l variable s had o n caniste r performance , the dat a wer e use d t o estimat e the variabilit yi n purg e respons e tha t coul d be expecte d among differen t canisters . I n additio n t o the evaluatio n o f th e purg e characteristic s o f severa l caniste r designs , th e effect s o f temperature , purg e ai r flowrat e an d caniste r agin

g o n hydrocarbo n stripping wer e als o investigate d t o a limite d extent .

-78

-II . Tes t Procedur e

Th e basi c objectiv e o f thi s tes t programwa s t o evaluat e th e hydrocarbo n desorptio n characteristic s o f variou s activate d carbo n canister s whe n loade d wit hrefueling emissions . Ther e wer e two basi c step s use d i n testing th e desorptio n characteristic s o f carbo n canisters . Th e firs t step involve d loadin g th e .canister s t o a n appropriat e leve l wit hth e chose n hydrocarbon s - i n thi s cas e refueling vapors . Th e second ste p wa s t o drawai r ove r the carbo n be d t o purg e i t o f it s hydrocarbo n load . During purging , th e chang e i n hydrocarbo n loa d wa s measure d a s a functio n o f the volume o f purg e ai r pulle d ove r th e carbo n bed . Eac ho f thes e step s i s describe d i n greate r detai l below . A . Caniste r Loadinq I n orde r t o evaluat e the stripping characteristic s o f an activate d carbo n canister , th e caniste r mus t firs t b e loade d wit hhydrocarbons . Becaus e adsorptio n an d desorptio n ar e mechanica l processe s theyar e affecte d b yth e siz e o f th e molecule s being adsorbe d o r desorbed . Therefore , the purg e characteristic s o f a carbo n bed can b e affecte d b ythe typ e o f hydrocarbon s use d t o loa d the canister . Becaus e th e informatio n gathere d in thi s progra m i s being use d i n th e developmen t o f a procedur e t o tes t th e performanc e o f refueling emissio n contro l systems , canister s wer e loaded wit hrefueling emissions . Refueling emission s wer e generate d b ydispensing fue l wit h a volatilit yo f approximatel y11. 5 ps i RVP int o a fue l tank fo r a 198 3 Cutlas s Supreme . Th e fillnec k for thi s fue l tank wa s modifie d s o tha t a tigh t sea l wa s forme d betwee n the fillnec k an d the fue l dispensing nozzl e whe n the nozzl e wa s inserte d int o th e fillneck . Th e fue l sende r uni t fo r thi s tank wa s als o modifie d b

yadding a

n orific e an

d nippl e t o whic ha s / 8 " vapo r lin e coul d b e attached . Thi s vapo r lin e route d th e vapor s displace d during th e refueling even t t o th e carbo n canister . Th e performanc e o f a caniste r during purg e i s als o affecte d b

yth e exten t t o whic hth e caniste r i s loaded . Th e mor e full yloade d th e caniste r is , th e highe r th e rat e a t whic h hydrocarbon s wil l b e remove d b ya give n volum e o f purg e air . Therefore , t o compar e th e result s o f variou s tests , i t i s desirabl e t o loa

d al l canister s t o th e same extent . Thi s programwa s designe d t o evaluat e th e performanc e o f activate d carbo n canister s ove r thei r norma l rang e o f hydrocarbo n loading . Therefore , i t seeme d logica l t o loa d th e canister s t o approximatel ythe "breakthrough " point . Th e breakthroughpoin t i s tha t poin t a t whic hth e caniste r ca n no longe r adsor bal l o f th e hydrocarbo n being pu t int o it , an d some hydrocarbo n passe s throughth e canister . Althoug hbreakthroughi s eas yt o defin e i n theory , ther e ar e severa l method s o f defining a practica l measur e o f breakthrough , eac ho f whic hcoul d resul t i n a -79

-P.8 1

somewha t differen t caniste r load fo r a give n canister . I n thi s program , th e breakthroughpoin t wa s detecte d using a flam e ionizatio n detecto r fro ma n exhaus t ga s analyzer . Initially , the analyze r prob e wa s place d nea r th e caniste r outle t an d th e hydrocarbo n concentratio n o f th e ga s leavin g th e caniste r wa s monitore d during the loadin g process . Whe n a sharp , persisten t ris e i n hydrocarbo n conten t wa s observed , caniste r loading wa s discontinued. . During th e earl ystage s o f th e tes t program , som e variabilit ywa s observe d betwee n caniste r loading s fo r test s performe d o n the same caniste r loade d t o the same breakthrough point . I t wa s hypothesize d tha t thi s variabilit ywa s du e t o the techniqu e use d t o determin e breakthrough , i.e . tha t becaus e the FI D picku

p wa s locate d s o nea r th e caniste r outle t tha t intermitten t "spikes " o f HC coming throughthe caniste r prio r t o breakthroughmigh t hav e bee n mistake n fo r breakthroughi n som e instances . I n a n attemp t t o ge t mor e repeatabl e caniste r loadings , th e tes t procedur e wa s change d somewhat . Instea d o f measuring a breakthroughpoin t fo r eac htes t o n a canister , a breakthroughpoin t wa s onl ymeasure d fo r the firs t tes t o n th e give n canister . Fo r eac hsubsequen t tes t on tha t canister , th e caniste r wa s loaded wit hth e vapor s displace d b ydispensing th e same numbe r o f gallon s o f fue l tha t wer e dispense d i n th e origina l test . Bl . Caniste r Purg e Hydrocarbon s ca n be strippe d fro ma carbo n be d b

ypassin g hydrocarbon-poo r ga s ove r the bed . I n thi s program , purg e wa s accomplishe d b

yusing a vacuu

msourc e t o pul l ai r ove r th e carbo n bed . In the purg e characterizatio n portio n o f the tes t program , bot hthe caniste r ambien t an d purg e ai r temperature s wer e maintaine d a t 95 ° F . Purg e ai r flowrat e wa s measure d usin g a rotomete r downstreamfromthe canister . Th e rotomete r rea d i n standar d cubi c fee t pe r minut e an d wa s monitore d throughou t th e caniste r purge . • Avalv e wa s installe d i n th e ai r suppl ylin e downstreamfromth e rotomete r an d wa s adjuste d throughou t th e purg e proces s t o maintai n th e desire d purg e ai r flowrate . Mos t o f the testing wa s performe d using a flowrat e o f approximatel yon e cfm , althoughflowrate s o f on e hal f an d two cf mwer e use d i n the investigatio n o f th e effect s o f purg e ai r flowrat e o n th e rat e o f hydrocarbo n removal . B2 . Measuremen t o f Caniste r Loading Th e performanc e o f a n activate d carbo n caniste r ca n b e define d i n term s o f th e chang e i n caniste r loading a s a functio n o f th e volume o f purg e ai r tha t i s pulle d throughth e canister . . Change s i n caniste r loading wer e measure d b y weighing th e caniste r befor e an d afte r loading an d a t severa l point s during the purg e process . Th e differenc e i n th e

•80

-caniste r mas s betwee n weighing s i s equa l t o th e chang e i n

caniste r load . Becaus e hydrocarbon s ar e mor e easil ystrippe d fro mthe carbo n be d whe n th e be d i s heavil yloaded , dat a wer e collecte d mor e frequentl yduring the initia l portio n o f th e purg e process . Canister s wer e weighe d a t the following times* : 0,1,2,3,4,5,7,9,11,13,15,20,25,35,50,70 , an d everytwent y minutes.thereafte r a s needed . Afte r completio n o f the tes t progra ma procedura l erro r wa s discovered . Specifically , th e time cloc k wa s no t stoppe d whe n the canister s wer e disconnecte d fro mthe purg e lin e fo r weighing , th e cloc k wa s allowe d t o continu e running fo r th e 5-1 0 second s tha t elapse d during eac hweighing . Th e consequenc e o f thi s erro r i s tha t slightl yles s purg e ai r actuall ypasse d throughthe canister s than i s represente d i n th e dat a table s accompanying thi s report . Althoughthi s dat a recording practic e skew s the results , i t shoul d ske wal l th e result s i n the same directio n an d approximatel yth e same amoun t fo r test s i n whic hthe purg e ai r flowrat e i s similar . T o compar e test s don e a t differen t flowrates , the dat a mus t b e adjuste d b

yshifting th e dat a t o accoun t for th e time los t during eac hcaniste r weighing . Th e onl ytime thi s issu e become s importan t i n thi s program i s in the evaluatio n o f purg e rat e o n strippin g characteristics . On e caniste r wa s purge d a t thre e differen t purg e rate s in orde r t o compar e the effec t o f purg e rat e o n hydrocarbo n stripping characteristics . Ate n second gap i n th e purg e at 2 cfm

represent s four time s a s muc hpurg e ai r a s doe s a ten second gap i n the purg e a t 1/ 2 cfm . I n orde r t o compar e the result s o f test s don e a t differen t purg e rates , the result s wer e correcte d b

yshifting eac hdat a poin t t o accoun t fo r th e gap s i n purg e ai r flowcorresponding t o caniste r weighings . I t wa s estimate d tha t eac hweighing too k approximatel yte n second s an d tha t th e caniste r wa s firs t disconnecte d afte r 5 5 second s o f purge . Th e correctio n procedur e i s mor e throughl ydescribe d i n th e discussio n o f th e result s o f th e test s dealin g wit h purg e rate .

Becaus e flowrat e i s constant , time elapse d betwee n caniste r weighing s i s proportiona l t o the amoun t o f ai r passing throughthe caniste r i n tha t time interval .

-81

-III . Canister s

Ideally , th e result s o f thi s tes t programwoul d provid e a characterizatio n o f th e performanc e o f typica l refuelin g emissio n contro l canister s tha t had bee n wel l age d o n refuelin g vapor s (i.e . theywoul d previousl yhav e bee n subjecte d t o multipl e refueling vapo r loading s an d subsequen t purges ) an d had bee n wel l maintained . Sinc e vehicle s d o no t presentl yhav e refuelin

g contro l systems , refueling canister s wer e unavailable . However , evaporativ e emissio n contro l canisters , whic hperformessentiall yth e same function , hav e bee n use d fo r mor e than a decade . Th e questio n the n became on e o f findin g severa l canister s tha t coul d be expecte d t o be i n goo d conditio n - tha t i s wel l maintaine d i n use . On e sourc e o f suc h canister s i s th e flee t o f vehicle s use d b yautomobil e manufacturer s t o gathe r emissio n contro l systemdurabilit yan d deterioratio n informatio n - durabilit ydat a vehicles . Thes e vehicle s ar e operate d fo r 50,00 0 mile s an d ar e wel l maintaine d an d service d during thi s mileag e accumulation . However , althoug hth e canister s o n th e durabilit yvehicl e wer e subjecte d t o a grea t dea l o f mileag e accumulation , th e canister s wer e probabl yno t a s wel l aged a s a typica l in-us e canister . Durabilit yvehicle s typicall yaccumulat e mileag e whil e operating o n the AM Adriving cycle . Thi s cycl e consist s o f essentiall ycontinuou s operatio n wit hinfrequen t stops . Thi s kin d o f operatio n result s i n infrequen t loading an d mor e extensiv e purg e than woul d normall yoccur . Althoughth e durabilit ycanister s mayno t hav e bee n full y aged , theywer e the bes t canister s readil yavailabl e fo r use . Thre e domesti c automaker s (Chrysler , Ford , an d Genera l Motors ) an d on e foreign make r (Nissan ) wer e contacte d an d aske d t o suppl yEPAwit ha caniste r fro ma durabilit ydat a vehicle . Al l o f thes e manufacturer s obliged . Adescriptio n o f eac ho f th e canister s fromth e durability-dat a vehicle s (durabilit ycanisters ) i s provide d i n Tabl e Al . Mos t o f the informatio n provide d i n th e tabl e i s self-explanatory , bu t on e itemdeserve s some furthe r attention . Tha t i s th e ite mlabele d "Treatmen t afte r 50 K Testing" . A s discusse d above , thes e canister s wer e take n of f o f durabilit ydat a vehicle s tha t ha d accumulate d 50,00 0 miles . Upo n completio n o f durabilit ymileag e accumulatio n an d testing , manufacturer s typicall ystor e thes e vehicle s i n cas e th e vehicle s ar e neede d fo r an yfurthe r testing . I t ca n b e see n tha t a t leas t thre e o f th e vehicle s had bee n store d outsid e betwee n th e time theyfinishe d mileag e accumulatio n an d th e time thei r canister s wer e removed . Also , on e manufacture r ra n the durabilit yvehicl e o n the tes t trac k prio r t o removing th e canister . Th e significanc e o f thi s informatio n i s discusse d i n the analysi s o f th e tes t results .

-82

-I

C O I Caniste r

Siz e (ml ) Activate d Carbo n Bas e Design Butane(l ) Working Capacity(gm ) Estimate d Design(2 ) H C Working Capacity(gm ) Approximat e Observe d H C Working Capacity(gm ) Vehicl e Typ e Caniste r Shap e Open/close d Botto m Treatmen t Afte r 50 K Testing Chrysle r

132 0

Wood
5 0

30-3 5

3 1

S-Body (Caravan , Voyager ) For d

92 5 Coa l
5 0

30-3 5

3 3

Taurus(3 ) Tabl eA l Descriptio no f

canister s G M 85 0
Woo d
3 5

cylindrica l Rectangula r
Closed

No Information Availabl e Close d

Complete d 50 K Jan 8 5 Store d outdoor s o n vehicl e unti l 8/28/8 5 Vent s covere d wit h tap e whe n remove d fro mvehicle . N o specia l treatmen t afte r removal . 20-2 5

3 5

J-Car (Sunbird ) Cylindrica l Open Complete d 50 K 7/19/8 5 Stored outdoor s o n vehicl e unti l 9/5/8 5 4 hr s AM

Amileag e accumulatio n (9 2 miles ) prio r t o caniste r remova l and delivery Nissan 123 0

Coconu t 5 7

34-4 0

5 7

Maxim a EPA 500 0

Woo d

26 0

160-18 0

19 0

Cylindrica l Open(4 ) Completed 50 K Ja n 8 4 Stored outdoor s unti l 10/85 . N o specia l treatmen t afte r remova l Cylindrica l Ope n

1 . Thes e ar e "Desig n Working capacities " a s give n in CERT application . Thos e tha t specify , specif yButan e W.C . 2 . 60-70 % o f "Desig n Butane Working Capacity " 3 . Vehicl e representin g a Taurus . 4 . Ope n bottomwit ha cove r ove r bottomwit ha 5/8 " openin g fo r ai r t o enter .

o oTw o othe r canister s wer e teste d i n additio n t o th e

durabilit ycanisters . On e wa s a ne w92 5 millilite r For d caniste r o f the same design a s the Ford durabilit ycanister . Th e result s o f the test s on the ne wcaniste r ar e use d i n compariso n wit hresult s o f the For d durabilit ycaniste r t o evaluat e the effect s o f aging . Th e sixt hcaniste r evaluate d i n thi s progra

mwa s a caniste r buil t b yEPAfor refueling tests . Thi s canistej r wa s no t actuall yteste d a s par t o f thi s tes t program , no r wa s the ' purg e procedur e use d identica l t o tha t use d i n testing the othe r canisters . I t was , however , loade d wit hrefueling vapor s an d purge d at approximatel y2 cfm . Th e caniste r i s cylindrica l wit ha volume o f abou t fiv e liter s ( h= 1 6 cm , r = 1 0 cm ) . Th e caniste r wa s loaded wit hWestvac o extrude d activate d carbon . Althoughthi s caniste r wa s no t full yaged prio r t o th e star t o f thi s program , i t ha d bee n expose d t o severa l refueling vapo r loading/purg e cycle s a s par t o f anothe r project . Th e result s o f test s o n thi s caniste r wer e use d t o compar e result s fro ma larg e caniste r t o thos e fromth e smalle r evap canisters . IV . Result s Th e dat a obtaine d in th e tes t progra

mar e presente d i n Table s A2- 1 throughA2-20 . Withi n th e tables , the dat a ar e organize d b

ycanister . Fo r eac htest , informatio n i s presente d on ; 1 ) refueling conditions , 2 ) purg e conditions , an d 3 ) caniste r mas s a s a functio n o f purg e volume . Fo r eac htest , the following informatio n i s presented :

° T T i , fue l tank temperatur e prio r t o refueling (°F ) ° T T f , fue l tan k temperatur e following refueling (°F ) ° T D, dispense d fue l temperatur e (°F ) ° Gallon s o f fue l dispense d (gallons ) ° T P , purg e ai r temperatur e (°F ) ° f , purg e ai r flowrat e (cfm ) ° t , cumulativ e purg e time elapse d prio r t o caniste r mas s measuremen t ° Caniste r mas s 1 ) prio r t o loading wit hrefueling vapors , 2 ) following H C loading , an d 3 ) followin g eac hpurg e interval . ° Cumulativ e decreas e i n caniste r mas s a t eac hpurg e interval . V . Analysi s Th e mai n purpos e o f thi s tes t program wa s t o compar e th e performanc e o f activate d carbo n canister s o f variou s design s unde r variou s condition s o f purg e temperatur e an d flowrate . Th e primaryinformatio n o f interes t wa s ho wreadil yth e

-84

-I

0 0 U l TES T NUMBE R

FUE L TRN

K TEMP . PRIO R T O REFUELING(deg . F ) FUE L TRN

K TEMP . FOLLOWING REFUELING(deg . F ) DISPENSE D FUE L TEMPERATUR E (deg . F ) GALLON S O F FUE L DISPENSE D PURG E AI R TEMPERATUR E <deg . F ) PURG E AI R FLO WRAT E (cfm. ) CANISTE R WEIGH T PRIO R T O LOADING(gms ) TABL E A2- 1 CHRYSLE R DURABILIT Y TEST S C l 7 2
7 3
7 3

9 5
1. 0
974 . a C 2
7 0
7 3
7 3

9 5
1. 0
86 0

Vo1um e o f purg e ai r (ft A 3 )

0 1 2 3 4 5 7 9 1 1 1 3 1 5 2 0 2 5 3 5 5 0 7 0 9 0 11 0 Caniste r

(grams ) 893 . 3 878. 6 876. 2 875. 4 874. 9 874. 5 874. 1 873. 7 873. 4 873 . 1 872. 8 871. 8 870. 9 869 . 1 866. 5 863. 6 861. 2 860. 0 i_

e i ghfc . Cumu1a t i v e H C

purge d (grams ) 0. 0 14. 7 17. 1 17. 9 18. 4 18. 8 19. 2 19. 6 19. 9 20. 2 20. 5 21. 5 22. 4 24. 2 26. 8 29. 7 32. 1 33. 3 Caniste r (grams ) 879. 8 865. 0 862. 0 860. 8 860. 2 859. 8 859. 6 859. 5 859. 4 859. 2 859. 1 858. 8 858. 5 857. 7 856. 7 ue i gh t Cumulativ e H C

purge d (grams ) 0. 0 14. 8 17. 8 19. 0 19. 6 20. 0 20. 2 20. 3 20. 4 20. 6 20. 7 21. 0 21. 3 22. 1 23. 1TRBL E R2- 2 CHRYSLE R DURRBILIT Y TEST S

l o o I TES T NUMBE R

FUE L TAN K TEMP . PRIO R T O REFUELIN G(deg . F ) FUE L TRN K TEMP . FOLLOWIN G REFUELIN G(deg . F ) DISPENSE D FUE L TEMPERATUR E (deg . F) . GALLON S O F FUE L DISPENSE D PURG E AI R TEMPERATUR E (deg . F ) PURG E AI R FLO WRAT E (cfm. ) CANISTE R WEIGH T PRIO R T O LORDIN G(gms ) C 3 7 1
6 5
6 5
1 0
9 5
1. 0
B6 0 C 4 7 0
6 5
6 5
1 0
9 5
1. 0
857. 9

Volum e o f purg e ai r (ft A 3 )

0 1 2 3 4 5 7 9 1 1 1 3 1 5 2 0 2 5 3 5 5 0 Caniste r weigh t

(grams ) 889. 0 879: 6 875. 3 872. 4 870. 2 868. 6 866. 1 864. 4 863. 3 862. 6 861. 9 860. 8 860. 0 859. 0 858. 1 Cumulativ e H C

purge d (grams ) 0. 0 9. 4 13. 7 16. 6 18. 8 20. 4 22. 9 24. 6 25. 7 26. 4 27. 1 28. 2 29. 0 30. 0 30. 9 Caniste r (grams ) 886. 6 879. 7 875. 1 871. 7 869. 6 867. 8 865. 4 863. 4 862. 4 861. 7 861. 0 859. 8 859. 1 858. 6 857. 7 w e i ghf c Cumulativ e H C

purge d (grams ) 0. 0 6. 9 11. 5 14. 9 17. 0 18. 8 21. 2 23. 2 24. 2 24. 9 25. 6 26. 8 27. 5 28. 0 28. 9

o oTRBL E R2- 3
FOR D DURHBILIT YTEST S

oo I TES T NUMBE RE l FUE L TRN KTEMP . PRIO RT O 7 8 REFUELIN G(deg . F ) FUE L TRN KTEMP . FOLLOWIN G7 5 REFUELIN G(deg . F ) DISPENSE D FUE L 7 5 TEMPERATUR E (deg . F ) GALLON S O F 8 FUE L DISPENSE D PURG E AI R 9 5 TEMPERATUR E (deg . F > PURG E AI R 0. 5 FLO WROT E (cfm ) CANISTE R WEIGH T 699. 1 PRIO R T O LOADING(gms ) E 2 7 5
7 5
7 5
9
9 5
0. 5
694. 3

Volum e o f purg e ai r (ft A 3 ) 0. 0 0. 5 1. 0 1. 5 2. 0 2. 5 3. 5 4. 5 5. 5 6. 5 7. 5 10. 0 12. 5 17. 5 25. 0 35. 0 45. 0 Caniste r

(grams ) 725. 1 716' . 2 713. 4 711. 4 709. 9 708. 9 707. 6 706. 5 705. 6 705. 1 704. 5 703. 4 702. 4 700. 4 698. 4 696. 4 694. 5 uie i gh t Cumulativ e H C

purge d(grams ) 0. 0 8. 9 11. 7 13. 7 15. 2 16. 2 17. 5 18. 6 19. 5 20. 0 20. 6 21. 7 22. 7 24. 7 26. 7 28. 7 30. 6 Cansiste r weigh t Cumulativ e H C (grams ) purge d (grams ) 719. 5 707. 1 703. 4 701. 1 699. 8 698. 5 697. 0 696. 0 695. 3 694. 7 694. 4 693. 8 693. 3 692. 1 691. 2 0 . 0 12. 4 16. 1 18. 4 19. 7 21. 0 22. 5 23. 5 24. 2 24. 8 25. 1 25. 7 26. 2 27. 4 28. 3I RUL E Rl'- 4

FOR D DURHBILIT YTEST S

oo 0 3 I TES T NUMBE R

FUE L TRN

K TEMP . PRIOR T O REFUELING(deg . F ) FUE L TRN

K TEMP . FOLLOWING REFUELING<deg . F ) DISPENSE D FUE L TEMPERRTUR E (deg . F ) GRLLON S O F FUE L DISPENSE D PURG E RI R TEMPERRTUR E (deg . F ) PURG E RI R FLO WRRT E (cfm ) CRNISTE R WEIGH T PRIO R T O LORDING(gms ) E 3
7 6
7 5
7 5

9 5
1- 0
691. 2 E 4 6 8
7 3
7 4

9 5
1. 0
686. 3

Volum e o f purg e ai r (ft A 3 )

0 1 2 3 4 5 7 9 1 1 1 3 1 5 2 0 2 5 3 5 5 0 7 0 Caniste r

(grams ) 716. 4 702-. 4 698. 6 696. 8 695. 5 694. 4 693. 0 691. 9 691. 4 690. 8 690. 5 690. 0 689. 5 688. 5 687. 2 686. 5 ue i gh t Cumu 1 atIv e H C

purge d (grams ) 0. 0 14. 0 17. 8 19. 6 20. 9 22. 0 23. 4 24. 5 25. 0 25. 6 25. 9 26. 4 26. 9 27. 9 29. 2 29. 9 Cansiste r weigh t Cumulativ e H C (grams ) 715 . 1 701. 4 697. 7 695. 5 694. 1 692. 9 691. 3 690. 0 689. 0 688. 5 688. 0 686. 7 686. 2 685. 3 684. 2 683. 1 purge d (grams ) 0. 0 13. 7 17. 4 19. 6 21. 0 22. 2 23. 8 25. 1 26 . 1 26. 6 27. 1 28. 4 28. 9 29. 8 30. 9 32. 0

0 0 CDI

c c 

### T TEST NUMBER

FUE L TAN

K TEMP . PRIO

R TO REFUELIN

G(deg . F ) FUE L TRN

K TEMP . FOLLOWIN

G REFUELIN

G(deg . F ) DISPENSE D FUE L TEMPERRTUR

E (deg . F ) GRLLON S O F FUE L DISPENSE D PURG E RIR TEMPERATUR

E (deg . F ) PURG E AIR FLO WRATE (cfm ) CANISTER WEIGH

T PRIO R T O LORDIN

G(gms ) TRBL E R2- 5 FOR D DURABILIT

Y TEST S E 5 6 9 72
7 4

9 5

683. 1 E 6 6 9 7 2
7 4 8 9 5

678. 2

Volum e o f purg e ai r (ft A 3 ) 0 2 4 6 8 1 0 1 4 1 8 22 2 6 3 0 4 0 5 0 7 0 10 0 14 0 Caniste r

(grams ) 713. 7 695. 0 691. 7 689. 5 688 . 1 687. 3 685. 9 684. 9 684 . 1 683. 7 683 . 1 682. 2 681. 6 680. 5 679. 6 678. 2 weigh t Cu m ulativ e H C

purge d (grams ) 0. 0 18. 7 22. 0 24. 2 25. 6 26. 4 27. 8 28. 8 29. 6 30. 0 30. 6 31. 5 32 . 1 33. 2 34. 1 35. 5 Cansiste r weigh t (grams ) 709. 2 689. 2 686

. 1 684. 0 683. 0 682. 2 681. 0 680

. 1 679. 2 678. 9 678. 7 677. 8 677. 3 676. 7 675. 9 675. 3 Cumulativ e H C purge d (grams ) 0 . 0 20. 0 23. 1 25. 2 26. 2 27. 0 28. 2 29. 1 30. 0 30. 3 30. 5 31. 4 31. 9 32. 5 33. 3 33. 9

C O oTRBL E R2- 6 GMDURABILIT Y TEST S

I s£> O I TES T NUMBE R FUE L TAN

K TEMP . PRIO R T O REFUELING(deg . F ) FUE L TAN

K TEMP . FOLLOWING REFUELING(deg . F ) DISPENSE D FUE L TEMPERATUR E (deg . F) . GALLON S O F FUE L DISPENSE D PURG E AI R TEMPERATUR E (deg . F ) PURG E AI R FLO WRAT E (cfm. ) CANISTE R WEIGH T PRIO R T O LOADING(gms ) B l 6 9
7 3 73

9 5
1. 0
445 . 1 B 2 7 0
7 3
7 4
8
9 5
1. 0
424. 1

Volum e o f purg e ai r (ft A 3 )

0 1 2 3 4 5 7 9 1 1 1 3 1 5 2 0 2 5 3 5 5 0 7 0 9 0 Caniste r

(grams ) 471. 1 459. 8 451. 5 449. 4 447. 7 447. 0 445. 6 444. 6 444. 0 443. 2 442. 5 441. 2 439. 9 437. 5 433. 8 429. 5 424. 7 weigh t Cumulativ e H C

pu r ge d(grams ) 0. 0 15. 3 19. 6 21. 7 23. 4 24. 1 25. 5 26. 5 27. 1 27. 9 28. 6 29. 9 31. 2 33. 6 37. 3 41. 6 46. 4 Caniste r (grams ) 451. 8 438. 4 433. 2 431. 1 429. 5 428. 7 427. 3 426. 2 425. 4 424. 6 424. 0 422. 6 421. 4 419. 7 417. 1 415. 0 414. 1 weigh t Cumulativ e H C

purge d(grams ) 0. 0 13. 4 18. 6 20. 7 22. 3 23. 1 24. 5 25. 6 26. 4 27. 2 27. 8 29. 2 30. 4 32. 1 34. 7 36. 8 37. 7TABL E A2- 7 GMDURABILIT Y TEST S

I TES T NUMBE R B 3

FUE L TAN

K TEMP . PRIO R T O 7 1 REFUELING(deg . F ) FUE L TANK TEMP . FOLLOWING6 5 REFUELING(deg . F ) DISPENSE D FUE L 6 5 TEMPERATUR E (deg . F ) GALLON S O F 1 0 FUE L DISPENSE D PURG E AI R 9 5 TEMPERATUR E (deg . F ) PURG E AI R 1. 0 FLOWROT E (cfm. ) CANISTE R WEIGH T 417. 1 PRIOR T O LOADING(gms ) 8 4 7 0
6 5
6 5
1 0
9 5
1. 0
417. 2

Volum e o f purg e ai r (ft A 3 ) 0 1 2 3 4 5 7 9 1 1 1 3 1 5 2 0 2 5 3 5 5 0 7 0 9 0 Caniste r

(grams ) 456. 1 446' . 1 442. 3 439. 7 437. 5 435. 9 433. 4 431. 2 429. 7 428. 5 427. 4 425. 1 423. 6 421. 0 418. 9 417. 1 weigh t Cumulativ e H C

purge d (grams ) 0. 0 10. 0 13. 8 16. 4 18. 6 20. 2 22. 7 24. 9 26. 4 27. 6 28. 7 31. 0 32. 5 35. 1 37. 2 39. 0 Ca n i ste r (grams ) 450. 2 443. 3 439. 1 436. 4 434 . 1 432. 3 429. 7 428. 0 426. 6 425. 5 424. 6 422. 9 421. 2 419. 3 417. 8 416. 6 welgh t Cumulativ e H C

purge d (grams ) 0. 0 6. 9 11. 1 13. 8 16. 1 17. 9 20. 5 22.2 23. 6 24. 7 25. 6 27. 3 29. 0 30. 9 32. 4 33. 6

C O N >TABL E R2- 8 G MDUPRBILIT YTEST S

I r o I TES T NUMBE RB 5

FUE L TAN

K TEMP . PRIO R T O 72 REFUELING(deg . F ) FUE L TAN

K TEMP . FOLLOWING6 5 REFUELING(deg . F ) DISPENSE D FUE L 6 5 TEMPERATUR E (deg . F ) GALLON S O F 1 0 FUE L DISPENSE D PURG E AI R 9 5 TEMPERATUR E (deg . F > PURG E AI R 1. 0 FLO WRAT E (cfm. ) CANISTE R WEIGH T 416. 8 PRIO R T O LOADING(gms ) B 6 7 3
6 5
6 5
1 0
9 5
1. 0
417. 6

Volum e o f purg e ai r (ft A 3 )

0 1 2 3 4 5 7 9 1 1 1 3 1 5 2 0 2 5 3 5 5 0 7 0 9 0 Caniste r

(grams ) 443. 8 437. 0 433. 9 431. 7 430. 0 428. 7 426. 9 425. 6 424. 6 423. 8 423. 2 421. 7 420. 6 419 . 1 417. 6 weigh t Cumulativ e H C

purge d (grams ) 0. 0 6. 8 9. 9 12. 1 13. 8 15. 1 16. 9 18. 2 19. 2 20. 0 20. 6 22. 1 23. 2 24. 7 26. 2 Caniste r (grams ) 450. 6 442. 6 438. 7 435. 6 433. 3 432 . 1 429. 3 427. 7 426. 5 425. 7 425. 0 423. 4 421. 9 420. 2 418. 5 417. 4 weigh t Cumulativ e H C

purge d (grams ) 0. 0 8. 0 11. 9 15. 0 17. 3 18. 5 21. 3 22. 9 24. 1 24. 9 25. 6 27. 2 28. 7 30. 4 32 . 1 33. 2 (no t use di n average )
CO C OTRBL E A2- 9 NISSA NDURABILIT Y TEST S

I V D TES T NUMBE R

FUE L TAN

K TEMP . PRIO R T O REFUELING(deg . F ) FUE L TAN

K TEMP . FOLLOWING REFUELING(deg . F ) DISPENSE D FUE L TEMPERATUR E (deg . F ) GALLON S O F FUE L DISPENSE D PURG E AI R TEMPERATUR E (deg . F ) PURG E AI R FLO WROT E (cfm. ) CANISTE R WEIGH T PRIO R T O LOADING(gms ) D l 7 0
6 5
6 5
2 5
9 5
1. 0
1103. 9 D 2 7 1
6 7
6 7
1 5
9 5
1. 0
1100. 2

Volum e o f purg e ai r (ft A 3 >

0 1 2 3 4 5 7 9 1 1 1 3 1 5 2 0 2 5 3 5 5 0 7 0 Caniste r

(grams ) 1163. 3 1152. 9 1148. 3 1145. 1 1141. 7 1139. 0 1134. 8 1132. 0 1128. 9 1126. 5 1124. 4 1120. 4 1116. 8 1111. 3 1104. 9 1100. 3 weigh t Cumulativ e H C

purge d(grams ) 0. 0 10. 4 15. 0 18. 2 21. 6 24. 3 28. 5 31. 3 34. 4 36. 8 38. 9 42. 9 46. 5 52. 0 58. 4 63. 0 Caniste r (grams ) 1162. 9 1154. 3 1150. 2 1146. 7 1143. 7 1141. 3 1136. 8 1132. 5 1129. 5 1126. 9 1124. 6 1120. 2 1117. 0 1112. 0 1107. 3 1103. 2 weigh t Cumulativ e H C

purge dCgrams ) 0. 0 8. 6 12. 7 16. 2 19. 2 21. 6 26 . 1 30. 4 33. 4 36. 0 38. 3 42. 7 45. 9 50. 9 55. 6 59. 7

C OTRBL E R2-1 0 NISSH NDURHBILIT YTEST S

l VD I TES T NUMBE RD 3

FUE L TAN K TEMP . PRIO RT O 6 6 REFUELIN G(deg . F ) FUE L TAN KTEMP . FOLLOWIN G5 9 REFUELIN G(deg . F ) DISPENSE D FUE L 5 3 TEMPERATUR E (deg . F ) GALLON S O F 1 6 FUE L DISPENSE D PURG E RI R 9 5 TEMPERATUR E (deg . F ) PURG E AI R 1. 0 FLO WROT E (cfm. ) CANISTE R WEIGH T 1097. 4 PRIO R T O LOADING(gms ) D4 6 6
5 9
5 9
1 6
9 5
1. 0
1094. 1

Volum e o f purg e ai r (ft A 3 ) 0 1 2 3 4 5 7 9 1 1 1 3 1 5 2 0 2 5 3 5 5 0 7 0 9 0 Caniste r

(grams ) 1150. 4 1137. 8 1131. 2 1126. 2 1121. 7 1118. 4 1114. 1 1110. 8 1108. 5 1106. 7 1105. 3 1102. 1 1100. 0 1097. 2 1094. 4 weigh t Cumulativ e H C

purge d (grams ) 0. 0 12. 6 19. 2 24. 2 28. 7 32. 0 36. 3 39. 6 41. 9 43. 7 45 . 1 48. 3 50. 4 53. 2 56. 0 Caniste r (grams ) 1145. 9 1138. 2 1133. 5 1130. 0 1126. 9 1124. 5 1120. 7 1117. 9 1115. 9 1114. 1 1112. 3 1109. 2 1107. 1 1103. 3 1098. 5 1093. 5 1089. 7 w e i gh t Cumulativ e H C pu r ge d (grams ) 0. 0 7.7 12. 4 15. 9 19. 0 21. 4 25. 2 28. 0 30. 0 31. 8 33. 6 36. 7 38. 8 42. 6 47. 4 52. 4 56. 2

C OI

VO U l I TES T NUMBE R FUE L TAN

K TEMP . PRIO

R T O REFUELIN

G(deg . F ) FUE L TAN

K TEMP . FOLLOWIN

G REFUELIN

G(deg . F ) DISPENSE D FUE L TEMPERATURE (deg . F ) GALLONS O

F FUE L DISPENSE D PURGE AI R TEMPERATURE (deg . F ) PURGE AI R FLO WROT E (cfm. ) CANISTE R WEIGHT PRIO R TO LOADIN

G(gms ) Vo1um e o f purg e ai r (ft A 3 )

0 1 2 3 4 5 7 9 1 1 1 3 1 5 2 0 2 5 3 5 5 0 7 0 9 0 D 5 64
5 9
5 9
1 6
9 5 TABL E R2-1 1

NISSA NDURABILIT Y TEST S D 6 6 5
5 9
5 8
2 6
9 5
1 . 0 1086. 8

Caniste r weigh t (grams ) 1127. 4 1120. 2 1115. 8 1112. 8 1110. 3 1108. 4 1104. 9 1102. 5 1101. 1 1099. 6 1098. 0 1095. 4 1093. 8 1091. 1 1088. 1 1085. 1 1082. 7 (no t use d i n Cu m ulativ e H C purge d (grams )

average ) 0. 0

7.2 11. 6 14. 6 17. 1 19. 0 22. 5 24. 9 26. 3 27. 8 29. 4 32. 0 33. 6 36. 3 39. 3 42. 3 44. 7 1. 0 1082. 1

Caniste r (grams ) 1146. 4 1138. 4 1133. 6 1129. 4 1126. 6 1124. 4 1120. 2 1117. 3 1114. 9 1113. 0 1111. 1 1107. 9 1105. 4 1101. 2 1096. 6 1090. 8 1086. 4 weigh t Cumulat i

pu r ge d ( 0. 0 8. 0 12. 8 17. 0 19. 8 22. 0 26. 2 29. 1 31. 5 33. 4 35. 3 38. 5 41. 0 45. 2 49. 8 55. 6 60. 0 H C

c o 0 >TABLE A2-1 2 NISSH NDURHBILIT

Y TESTS

l V D I TEST NUMBER D 7

FUE L TRN

K TEMP . PRIOR TO 5 9 REFUELIN

G(deg . F ) FUE L TRN

K TEMP . FOLLOWIN

G5 8 REFUELIN

G(deg . F ) DISPENSE D FUE L 5 8 TEMPERATUR

E (deg . F ) GALLON S O F 22. 5 FUE L DISPENSE D PURG E AI R 9 5 TEMPERATUR

E (deg . F ) PURG E AIR 1. 0 FLO WROTE (cfm. ) CANISTER WEIGH

T 1059. 1 PRIO R T O LOADIN

G D 8 6 6 6 0 6 0 1 6 11 5 1. 0 1011. 4

ai r o f purg e t A 3 ) 0 1 2 3 4 5 7 9 1 1 1 3 1 5 2 0 2 5 3 5 5 0 7 0 9 0 Ca n i s tei

Cgrams ) 1119. 1 1114. 7 1112. 0 1109. 8 1107. 6 1105. 9 1102. 6 1099. 9 1098. 2 1096. 6 1095. 3 1092. 0 1089. 2 1084. 7 1079. 3 1073. 0 1068. 5 weigh t Cumulativ e H C

purge d (grams ) 0. 0 4. 4 7 . 1 9. 3 11. 5 13. 2 16. 5 19. 2 20. 9 22. 5 23. 0 27. 1 29. 9 34. 4 39. 8 46. 1 50. 6 Caniste r < grams ) 1061. 5 1058. 3 1056. 7 1055. 3 1054. 0 1052. 8 1051. 0 1049. 7 1048. 7 1048. 0 1047. 3 1046. 3 1045. 5 1044. 0 1042. 5 1040. 6 1038. 8 weigh t Cumulativ e H C

purge d (grams ) 0. 0 3. 2 4. 8 6. 2 7. 5 8. 7 10. 5 11. 8 12. 8 13. 5 14. 2 15. 2 16. 0 17. 5 19. 0 20. 9 22. 7

C OI VD

-• J TES T NUMBE R D 9 FUE L TAN

K TEMP . PRIO R T O 6 7 REFUELING(deg . F ) FUE L TAN

K TEMP . FOLLOWING5 9 REFUELING(deg . F ) DISPENSE D FUE L 5 9 TEMPERATUR E (deg . F ) GALLON S O F 1 6 FUE L DISPENSE D PURG E AI R 11 5 TEMPERATUR E (deg . F ) PURG E AI R 1. 0 FLO WROT E (cfm. ) CANISTE R WEIGH T 1038. 8 PRIO R T O LOADING I MOL E 02-1 3 NISSHNDURABILIT Y TEST S

Volum e o f purg e ai r (ft A 3 >

0 1 2 3 4 5 7 9 11 1 3 1 5 2 0 2 5 3 5 5 0 7 0 9 0 Caniste r

<grams ) 1093. 1 1088. 2 1085. 5 1083. 4 1081. 7 1080. 3 1078. 0 1076. 3 1075. 0 1073. 9 1072. 7 1071. 0 1069. 6 1067. 4 1064. 8 1061. 8 1058. 8 weigh t Cumulativ e H C

purge d (grams ) 0. 0 4. 9 7. 6 9. 7 11. 4 12. 8 15. 1 16. 8 18. 1 19. 2 20. 4 22. 1 23. 5 25. 7 28. 3 31. 3 34. 3

CO 0 0TRBL E n2-1 4 NE WFOR D TEST S

I VD O O I TES T NUMBE R

FUE L TRN

K TEMP . PRIO R T O REFUELING(deg . F ) FUE L TAN

K TEMP . FOLLOWING REFUELING(deg . F ) DISPENSE D FUE L TEMPERATUR E (deg . F ) GALLON S O F FUE L DISPENSE D PURG E RI R TEMPERATUR E (deg . F ) PURG E AI R FLO WROT E (cfm. ) CANISTE R WEIGH T PRIOR T O LOADING(gms ) Volum e o f purg e ai r (ft A 3 )

0 1 2 3 4 5 7 9 1 1 1 3 1 5 2 0 2 5 3 5 5 0 7 0 9 0 A l
7 5 7 6 7 6 1 2 9 5 1. 0
587. 9
Caniste r (grams ) 635. 8 620. 5 616. 5 614. 1 612. 1 610. 8 608. 8 607. 6 606. 4 605. 6 604. 9 603 . 1 601. 7 599. 4 596. 8 594. 4 weigh t Cumu1a t i v e H C

purge d (grams ) 0. 0 15. 3 19. 3 21. 7 23. 7 25. 0 27. 0 20. 2 29. 4 30. 2 30. 9 32. 7 34 . 1 36. 4 39. 0 41. 4 0 2 6 9 7 5 7 5 1 2
9 5 1. 0

Caniste r (grams ) 634. 7 619. 5 614. 0 612. 1 610. 3 609. 2 607. 5 606. 5 605. 7 605. 0 604. 4 602. 9 601. 8 599. 7 597. 5 595. 6 5 34. 4 594 .

w e i gh t 7
Cumulativ e H C

purge d (grams ) 0. 0 15. 2 19. 9 22. 6 24. 4 25. 5 27. 2 28. 2 29. 0 29. 7 30. 3 31. 8 32. 9 35. 0 37. 2 39 . 1 40. 3

C O COTRBL E R2-1 5 NE WFOR D TEST S

I v_ 5 TES T NUMBE R R 3

FUE L TAN

K TEMP . PRIO R T O 7 4 REFUELING(deg . F ) FUE L TAN

K TEMP . FOLLOWING7 5 REFUELING(deg . F ) DISPENSE D FUE L 7 5 TEMPERRTUR E (deg . F ) GALLON S O F 1 0 FUE L DISPENSE D PURG E RI R 9 5 TEMPERATUR E (deg . F ) PURG E RI R 1. 0 FLO WRAT E (cfm. ) CANISTE R WEIGH T 594. 4 PRIO R T O LOADING<gms ) Volum e o f purg e ai r (ft A 3 )

0 1 2 3 4 5 7 9 1 1 1 3 1 5 2 0 2 5 3 5 5 0 7 0 9 0 Caniste r weigh t

(grams ) 6 34. 2 617. 4 613. 0 610. 4 609. 0 608. 0 606. 5 605. 3 604. 6 603. 9 603. 3 602. 0 600 . B 599 . 1 597 . 1 595. 8 594. 7 Cumulativ e H C

purge d (grams ) 0. 0 16. 8 21. 2 23. 8 25. 2 26. 2 27. 7 28. 9 29. 6 30. 3 30. 9 32. 2 33. 4 35 . 1 37 . 1 38. 4 39. 5 R4 7 5
7 5
7 5
1 2
9 5
1. 0
595 . I
Caniste r (grams ) 630. 8 616. 8 614. 0 611. 1 609. 9 609. 0 607. 9 607. 2 606. 6 605. 9 605. 4 604. 4 603. 3 601. 4 599. 7 598. 3 597. 3 weigh t Cumulativ e H C

pu r ge d (grams ) 0. 0 14. 0 16. 8 19. 7 20. 9 21. 8 22. 9 23. 6 24. 2 24. 9 25. 4 26. 4 27. 5 29. 4 31. 1 32. 5 33. 5TABL E A2-1 6 NE WFORD TEST S

o o I TES T NUMBE R FUE L TANK TEMP . PRIOR T O REFUELING(deg . F ) FUE L TANK TEMP . FOLLOWING REFUELING(deg . F ) DISPENSE D FUE L TEMPERATUR E (deg . F ) GALLON S O F FUE L DISPENSE D PURG E AI R TEMPERATUR E (deg . F > PURG E AI R FLO WRAT E (cfm. ) CANISTE R WEIGH T PRIO R T O LOADING(gms ) Volum e o f purg e ai r (ft A 3 >

0 1 2 3 4 5 7 9 1 1 1 3 1 5 2 0 2 5 3 5 5 0 7 0 9 0 R 5 7 0
7 4
7 4
1 0
9 5
1. 0
602. 4
Caniste r (grams ) 636. 3 622. 0 618. 8 616. 6 615. 3 614. 3 613. 0 612. 2 611. 4 610. 7 610. 1 608. 8 607. 6 606. 1 604. 6 603. 3 602. 8 ueigh t Cumulativ e H C

purge d (grams ) 0. 0 14. 3 17. 5 19. 7 21. 0 22. 0 23. 3 24. 1 24. 9 25. 6 26. 2 27. 5 28. 7 30. 2 31. 7 33. 0 33. 5 R 6 6 9
74
7 4
1 0
9 5
1. 0

Caniste r (grams ) 640. 8 628. 3 622. 0 620. 1 616. 2 614. 3 612. 8 611. 8 610. 7 610. 0 609. 3 608. 0 606. 8 604. 7 602. 7 602 . weigh t 8
Cumulativ e H C

purge d (grams ) 0. 0 12. 5 18. 8 20. 7 24. 6 26. 5 28. 0 29. 0 30. 1 30. 8 31. 5 32. 8 34. 0 36. 1 38. 1

"U N >TRBL E R2-1 7 NE W FOR DTEST S TES T NUMBE R FUE L TRN KTEMP . PRIO RT O REFUELIN GCdeg . F ) FUE L TRN KTEMP . FOLLOWIN G REFUELIN GCdeg . F > DISPENSE DFUE L TENPERRTUP E (dog . F ) GRLLON S O F FUE L DISPENSE D PURG E RI R TENPEPRTUR E Cdeg . PURG E RI R FLO W RRT E (cf«. > F >

CHNISTE RWEIGH T PRIO RT OLORDIN Gigots ) o Volum e o f pw r

«i r <ft~3 >

O 1 2 3 4 5 7 9 1 1 1 3 1 5 2 0 2 5 3 5 5 0 ? 0 9 0 1 I O 13 0 IS O i? o IS O 21 0 g e Caniste r

(grams ) 671. 5 660. 0 658. 6 657 . 1 65-4. 3 651 . 7 6-48. 2 646 . O 644. 4 6-42. 8 642 . 1 640. 2 638. 8 636. 4 633. 8 631. 6 629. 9 R 7

7 2
6 4
6 4
1 3
9 5
1. 0
627. 4 R 8 71
6 2
6 2
1 3
11 5
l. O
628 . 1 Cumulativ e H C purge d(grama ) O. O 11. 5 12. 9 14. 4 17. 2 19. 8 23. 3 25. 5 2 7 . 1 28. 7 29. 4 31. 3 32. 7 35 . 1 37. 7 39. 9 41. 6 Caniste r ueigh t (grams ) 665. 8 662

. O 659.- 4 657. 5 656

. 1 65*1- 9 653. 2 651. 8 650. 9 650. 2 649. 6 648. 2 647. 3 646

. O 644. 4 643

. 1 6-12

. O 640. 5 639

. 1 637. 9 636. 6 635. 6 634

. 7 Cumu1a t i v e H C pu r ge d< g r ams ) O. O 3. 8 6. 4 8. 3 9. 7 10. 9 12. 6 14. O 14. 9 15. 6 16. 2 17. 6 18. 5 19. 8 21. 4 22. 7 23. 8 25. 3 26. 7 27. 9 29. 2 30. 2 31 . I

T J C OTR8LE R2-1 8 NEWFOR D TEST S

o I TES T NUMBE R

FUE L TRN

K TEMP . PRIO

R TO REFUELIN

G(deg . F ) FUE L TRN

K TEMP . FOLLOWIN

G REFUELIN

G(deg . F ) DISPENSE D FUE L TEMPERATURE (deg . F ) GALLONS OF FUE L DISPENSE D PURGE RI R TEMPERATURE (deg . F ) PURGE AI R FLO WRAT E (cfm. ) CRNISTE R WEIGH

T PRIO R T O LOADIN

G(gms ) Volum e o f purg e ai r (ft A 3 ) 0 1 2 3 4 5 7 9 1 1 1 3 1 5 2 0 2 5 3 5 5 0 7 0 9 0 R 9 6 7 6 1 6 1 1 3 11 5 1. 0 634. 5 RI O 6 6 6 1 6 1 1 3 11 5 1. 0 635. 8
Caniste r (grams ) 674. 7 665. 0 659. 8 657. 5 655. 0 653. 7 651. 1 649. 5 648. 2 647. 2 646. 6 645. 0 643. 6 641. 9 639. 5 637. 8 636. 0 weigh t Cumulativ e H C

purge d (grams ) 0. 0 9. 7 14. 9 17. 2 19. 7 21. 0 23. 6 25. 2 26. 5 27. 5 28. 1 29. 7 31. 1 32. 8 35. 2 36. 9 38. 7 Caniste r (grams ) 667. 3 659. 5 656. 1 653. 6 651. 9 650. 7 648. 7 647. 3 646. 3 645. 6 644. 9 643. 6 642. 7 641. 0 639. 1 638. 0 637. 0 u e i gh t Cumulativ e H C

purge d (grams ) 0. 0 7. 8 11. 2 13. 7 15. 4 16. 6 18. 6 20. 0 21. 0 21. 7 22. 4 23. 7 24. 6 26. 3 28. 2 29. 3 30. 3

J >TABL E R2-1 9 NE WFOR D TEST S

o c o TES T NUMBE RAl l

FUE L TAN KTEMP . PRIO RT O 7 1 REFUELIN G(deg . F ) FUE L TRN KTEMP . FOLLOWIN G6 1 REFUELIN G(deg . F ) DISPENSE D FUE L 6 1 TEMPERATUR E (deg . F ) GALLON S O F 1 3 FUE L DISPENSE D PURG E AI R 7 5 TEMPERATUR E (deg . F ) PURG E AI R 1. 0 FLO WRAT E (cfm. ) CANISTE R WEIGH T 636. 5 PRIO R T O LORDIN G(gms ) R1 2 6 7
6 1
6 1
1 3
7 5
1. 0
643. 4
Volum e o f purg e ai r (ft*3 )

0 1 2 3 4 5 7 9 1 1 1 3 1 5 2 0 2 5 3 5 5 0 7 0 9 0 Caniste r

(grams ) 673. 9 668. 3 665. 7 663. 7 662. 1 661. 0 659. 0 657. 8 656. 8 656. 0 655. 5 653. 6 652. 9 650. 9 648. 6 645. 9 643. 4 hi e i gh t Cumulativ e H C

purge d(grams ) 0. 0 5. 6 8. 2 10. 2 11. 8 12. 9 14. 9 16. 1 17. 1 17. 9 18. 4 20. 3 21. 0 23. 0 25. 3 28. 0 30. 5 Caniste r (grams ) 678. 2 671. 0 667. 2 664. 7 663. 0 661. 7 659. 5 657. 8 656. 9 655. 9 655. 1 653. 3 651. 8 649. 7 646. 8 643. 7 u e i gh t Cumulativ e H C

purge d (grains ) 0. 0 7. 2 11. 0 13. 5 15. 2 16. 5 18. 7 20. 4 21. 3 22. 3 23. 1 24. 9 26. 4 28. 5 31. 4 34. 5

CJ !TABL E R2-2 0 NEWFOR D TEST S

o •t
l TES T NUMBER

FUE L TAN

K TEMP . PRIO

R TO REFUELIN

G(deg . F > FUE L TAN

K TEMP . FOLLOWIN

G REFUELIN

G(deg . F ) DISPENSE D FUE L TEMPERATURE (deg . F ) GALLONS O

F FUE L DISPENSE D PURGE AI R TEMPERATURE (deg . F ) PURGE AI R FLO WRATE (cfm. ) CANISTE R WEIGH

T PRIO R T O LORDIN

GCgms ) Volum e o f purg e ai r (ft A 3 ) O 1 2 3 4 5 7 9 1 1 1 3 1 5 2 0 2 5 3 5 5 0 7 0 9 0 A1 3 6 7 6 1 6 1 1 3
7 5 1. 0 650. 4 R1 4 6 9 6 1 6 1 1 3
7 5 1. 0 643. 4
Caniste r (grams ) 681. 4 672. 4 668. 3 665. 8 663. 8 662. 4 660. 4 658. 8 658. 0 657. 1 656. 7 655. 2 654. 3 652. 5 650. 4 649. 5 u e i gh t Cumulativ e H C

purge d (grams ) 0. 0 9. 0 13. 1 15. 6 17. 6 19. 0 21. 0 22. 6 23. 4 24. 3 24. 7 26. 2 27. 1 28. 9 31. 0 31. 9 Caniste r (grams ) 683. 1 676. 1 672. 3 670. 3 668. 4 667. 3 665. 0 663. 7 662. 7 661. 9 661. 4 660. 1 659. 2 656. 8 654. 7 652. 6 650. 4 ueigh t Cumulativ e H C

purge d (grams ) 0. 0 7. 0 10. 8 12. 8 14. 7 15. 8 18. 1 19. 4 20. 4 21. 2 21. 7 23. 0 23. 9 26. 3 28. 4 30. 5 32. 7

b >P. 7

caniste r release s hydrocarbo n i n respons e t o a give n volum e o f purg e ai r whe n purge d at a give n flowrat e an d temperature . Becaus e th e amoun t o f HC purge d doe s no t varylinearl ywit hth e purg e ai r volume , caniste r performanc e shoul d b e compare d ove r a continuu

mrathe r than a t an ygive n time during th e purg e sequence . Th e simples t wayt o d o thi s i s wit ha graphica l representatio n o f the result s whic hwer e presente d i n th e previou s section . Throughou t th e res t o f th e dat a analysis , canister s ar e compare d b ycomparing plot s o f cumulativ e H C purge d fromthe caniste r (ordinate ) versu s th e cumulativ e volume o f purg e ai r pulle d throughthe caniste r prio r t o th e give n mas s measuremen t (abscissa) . Th e dat a point s wer e connecte d wit ha smoot hcurv e t o approximat e th e performanc e o f the caniste r at al l time s i n the purg e sequence . Becaus e ther e i s some variabilit yi n caniste r performanc e fromon e tes t t o anothe r th e result s fro m a serie s o f test s o n a give n caniste r wer e average d t o fin d a "typical " purg e curv e fo r eac hseries . Th e average s wer e foun d b yfinding th e averag e amoun t o f hydrocarbo n purge d fromth e caniste r a t eac h dat a point . Th e averag e value s wer e foun d an d plotted , an

d a smoot hcurv e draw n betwee n the averag e values . Mos t o f th e analysi s i n thi s repor t i s base d o n the averag e curve s develope d a s describe d above . Th e remainde r o f the analysi s o f result s i s divide d int o five sections . Th e firs t sectio n addresse s some difference s tha t wer e observe d betwee n the firs t tes t o r test s performe d o n a give n durabilit ycaniste r an d late r test s performe d o n th e same canister . Th e nex t sectio n touche s o n th e effect s o f caniste r agin

g b yevaluating th e result s fro m sequentia l test s o n a ne wcaniste r an d b ycomparing result s o f test s performe d a n age d (durability ) For d caniste r o f identica l design . Th e effec t o f purg e rat e i s the n briefl ydiscusse d followe d b ya descriptio n o f the result s o f the test s designe d t o evaluat e the effec t o f temperatur e on purg e rate . Th e nex t sectio n describe s the mos t substantia l portio n o f the wor k i n thi s tes t program . Tha t i s the developmen t o f a "representative " purg e curv e fo r eac hcaniste r typ e examine d i n thi s program . Th e fina l sectio n discusse s the interna l temperatur e o f th e refueling caniste r during th e purg e process . A . Initia l Test s versu s Averag e Curve s A s par t o f the analysi s o f th e caniste r tes t results , th e result s fromtest s performe d o n individua l canister s unde r simila r condition s o f purg e wer e plotte d individuall yo n the same se t o f axes . Whe n plotte d . i n thi s way , th e result s from thre e o f th e four durabilit ycanister s teste d showa patter n i n the tes t results . Th e patter n observe d wa s tha t th e shap e o f

-105

-P. 8

the curv e generate d fro mthe result s o f th e firs t on e o r tw o test s o n a give n caniste r wa s markedl ydifferen t from th e shap e o f the curv e generate d i n subsequen t tests . I n tw o o f thes e thre e case s the caniste r working capacit yappeare d t o improv e afte r the firs t fewtests , an d i n the third cas e th e caniste r working capacit yappeare d t o decreas e afte r th e firs t fe w cycles . Th e durabilit ycanister s supplie d b yFor d an

d Chrysle r bot hshowe d a lowe r working capacit yi n th e initia l test s tha n i n subsequen t tests . Figur e A l show s two curve s generate d fro m the result s o f th e test s o n the Chrysle r durabilit ycanister . Th e curv e labele d "Initial " wa s generate d b yaveraging th e dat a take n i n th e firs t an d secon d test s o n th e canister . Th e curv e labele d "Average " i s th e averag e o f the othe r two test s performe d o n tha t canister . Th e result s o f th e firs t two test s wer e nearl yidentica l t o eac hothe r a s wer e th e result s o f th e third an

d fourt htests . A n examinatio n o f Figur e A l show s tha t th e purg e curv e representing th e initia l test s i s differen t fromtha t representing late r test s in term s o f bot hworkin g capacit y(lowe r fo r initia l tests ) an d shape . Asimila r patter n i s see n i n Figur e A2 . Figur e A 2 show s result s o f test s performe d o n the durabilit ycaniste r provide d b yFor d Moto r Company . A

n examinatio n o f the plot s show s a lowe r workin g capacit yan

d a distinctl ydifferen t patter n o f purg e respons e i n th e initia l tes t a s compare d wit hlate r tests . Result s o f th e test s performe d on th e durabilit ycaniste r supplie d b

yGenera l Motor s ar e show n i n Figur e A3 . A s i n th e test s o n the Ford an d Chrysle r durabilit ycanisters , ther e i s a noticeabl e differenc e betwee n th e initia l test s an d late r tests . I n thi s case , however , the working capacit yobserve d i n the initia l tes t o n the caniste r i s greate r than th e capacit y observe d i n succeeding tests . Th e result s o f th e initia l test s o n th e durabilit y canister s raise d two questions : 1 ) Wh ydi d the initia l tes t (or tests ) o n thes e durabilit ycanister s produc e differen t result s than subsequen t tests ? an d 2 ) Wh

ydi d th e capacitie s o f th e Ford an

d Chrysle r canister s apparentl yincreas e ove r th e capacit yobserve d i n thei r initia l tests , whil e th e capacit yo f the Genera l Motor s caniste r appeare d t o decrease ? On e possibl e explanatio n o f thes e result s i s describe d i n th e followin g paragraph . An increas e i n caniste r working capacit ywit htim e suggest s tha t th e caniste r i s being purge d somewha t mor e full y than i t recentl yhad been , an d tha t some har d t o remov e hydrocarbon s ar e being strippe d fro mth e carbon . Conversely , a decreas e i n caniste r working capacit ysuggest s tha t th e caniste r wa s initiall yfairl ywel l stripped , bu t tha t

-106

-FIGUR E A- 1 

# INITIA LCURVE S VS

. AVERAG E CURV E

I h- 107-(SLU

" O
3 Q . 

### O I 0 > > oITlU
Z J O 3 0

2 8 2 6 2 4 2 2 2 0 1 8 1 6 1 4 1 2 1 0 8 Chrysle rDurabilit y AVERAG E

INITIA L

0 2 0 4 0 Purg e Volum e (cubi cft ) 

# J 2FIGUR E A- 2



# INITIA LCURV E VS

. AVERAG E CURV E

< — . (T> E o > V - * • o a > o > t ~ 3 Q

_ U I I T> o 3 E 3 u 3 2

3 0 2 8 2 6 2 4
o o 2 0 1 8 1 6 1 4 1 2 1 0 8 6 4 2 0 For d Durabilit y

0 2 0 4 0 Purg e Volum e (cubi cft )

oo V O I U O E o > x > a > 0 1 3 C L O I
>
3 E 3 

### o FIGUR E A- 3



# INITIA LCURV E vs . AVERAG E CURV E G M Durabilit y

Purg e Volum e (cubi cft )load/purg e cycle s ar e increasing the caniste r "heel. "

Therefore , the differenc e in the result s o n the For d an d Chrysle r canister s versu s the Genera l Motor s caniste r coul d hav e bee n du e t o the conditio n o f the caniste r prio r t o testing . Th e result s sugges t tha t th e Genera l Motor s caniste r wa s fairl ywel l purge d an d th e Ford an

d Chrysle r canister s ha d mor e o f a residua l load . Thi s wa s exactl yth e case . Eac ho f thes e durabilit ycanister s (Ford , Chrysler , G.M. ) wa s take n of f o f a vehicl e tha t had complete d it s durabilit ytesting month s earlier . A s can be see n in Tabl e Al , the Ford an d G Mvehicle s wer e store d outdoor s betwee n completio n o f durabilit ytesting an d th e time o f caniste r removal . (Thoug hn o informatio n wa s available , i t i s saf e t o assume tha t the Chrysle r vehicl e wa s treate d similarly) . During tha t time th e canister s wer e subjecte d t o multipl e diurnal s an d coul d b e expecte d t o hav e bee n thoroughl ysaturated . Th e differenc e betwee n th e For d an d the Genera l Motor s canister s i s tha t Genera l Motor s attempte d t o "stabilize " th e caniste r prio r t o delivering i t t o EPA . I n thi s case , stabilizatio n wa s achieve d b ydriving the vehicl e fo r four hour s o f AM Amileag e accumulatio n wit hth e evap caniste r onboard . Thi s typ e o f operatio n probabl ypurge d th e caniste r quit e thoroughly , an d le d t o th e differenc e betwee n the plot s o f th e initia l test s o n thes e canisters . I t shoul d be pointe d ou t her e tha t the Nissa n caniste r wa s als o subjecte d t o multipl e diurna l loading s befor e deliveryt o EPA . Ther e was , however , no significan t differenc e betwee n th e plo t o f the initia l caniste r test s an d late r tests . B . Caniste r Aging Caniste r aging refer s t o the proces s b ywhic han activate d carbo n be d lose s working capacit ywit hrepeate d load/purg e cycle s unti l a stabilize d leve l i s reached . O n a molecula r level , aging i s th e proces s b ywhic hcertai n molecule s ar e adsorbe d ont o the carbo n be d i n suc ha waytha t theyar e very difficul t t o remove . Althoughi t migh t be possibl e t o remov e themwit han extensiv e amoun t o f purging , the effectiv e workin g capacit yo f th e carbo n be d unde r normal , in-us e purg e mode s i s reduced . Th e age d conditio n appear s t o develo p graduall yove r repetitiv e load/purg e cycles . On e o f the secondarygoal s o f thi s programwa s t o evaluat e th e magnitud e o f th e agin g effect . Becaus e o f th e extensiv e amoun t o f testing tha t woul d be required , i t wa s outsid e th e scop e o f thi s projec t t o ag e a ne wcaniste r from it s virgi n stat e t o it s stabilize d level . I t i s unlikel ytha t aging coul d b e observe d afte r th e limite d numbe r o f cycle s possibl e during thi s tes t program . Figur e A 4 show s th e firs t si xtest s performe d o n th e ne wFor d canister . Althoug hth e firs t fiv e

-110

-FIGUR E A- 4

i 

### V tn 

### t o >

" O 9> O i i

_ 3 

## o I > o 3 E 3 

### o 4 0

3 5

3 0

2 5

2 0

1 5

1 0 

# FOR D DURABILITY AGIN G

0 0 2 0 4 0 Purg e Volum e (cubi cft )

T l CJP.1 4

test s ten

d t o sho wa decreas e i n capacit ywit htime , th e sixt h tes t show s the secon d highes t working capacit yi n th e group . Thi s suggest s tha t the differenc e betwee n test s i s being maske d b ytest-to-tes t variabilit yan d no tren

d i n working capacit y can be establishe d fro m thi s data . Becaus e o f the time involve d i n agin g a virgi n canister , a n alternativ e metho d o f evaluating th e effec t o f caniste r agin g wa s needed . On e logica l approac hwa s t o performa serie s o f test s o n a ne wcaniste r (a s outline d above ) an d t o compar e the result s o f thes e test s wit hth e result s o f a serie s o f test s don e o n an age d caniste r o f identica l design . Figur e A 5 show s four plots . Th e two uppe r curve s wer e generate d fromth e result s o f th e test s o n the newcanister . Th e top curv e i s th e purg e record from

th e initia l tes t o n th e virgi n canister . Th e nex t curv e i s an averag e o f the si xplot s show n previousl yi n Figur e A4 . Th e lowe r tw o curve s i n Figur e A 5 wer e generate d fro mthe result s o f the test s o n th e For d durabilit ycanister . Th e lowes t show s th e result s o f th e firs t tes t performe d o n th e durabilit ycaniste r afte r i t wa s receive d b yEPAan

d th e fina l plo t (labele d "durabilit yaverage" ) show s the averag e o f al l the test s performe d o n the durabilit ycanister . Figur e A 5 illustrate s a fe wsignifican t points . First , the origina l tes t o n the virgi n caniste r show s th e highes t working capacit yo f al l the test s performe d o n the ne wan d th e durabilit ycanisters . Second , the averag e working capacit y observe d i n the test s on the ne wcaniste r i s highe r tha n th e averag e working capacit yo f th e durabilit ycanister . Thi s suggest s tha t some aging ha s take n place . Finally , th e firs t tes t on th e durabilit ycaniste r showe d th e lowes t workin g capacit yo f al l the tests , suggesting tha t th e caniste r may have "aged " mor e than the averag e durabilit yplo t show s an d tha t the repeate d benc hpurg e performe d i n thi s programha s restore d some capacity . Althoughth e result s o f thes e test s ar e no t a definitiv e measur e o f th e effect s o f aging , th e result s do sugges t tha t the durabilit ycaniste r ha s bee n age d t o some extent . I n thi s case , the durabilit ycaniste r appear s t o have los t abou t twent ypercen t o f it s origina l capacity . C . Purg e Rat e Anothe r secondarygoa l o f thi s tes t programwa s t o evaluat e th e effec t tha t th e rat e o f purg e ai r flo wha s o n caniste r stripping characteristics . I f th e rat e o f hydrocarbo n stripping i s independen t o f purg e ai r flowrat e the n th e cumulativ e amoun t o f hydrocarbo n purge d fro mth e caniste r woul d be a constan t functio n o f th e volum e o f purg e ga s passin g throughth e canister . Trace s o f cumulativ e hydrocarbo n purge d versu s volume o f purg e ai r pulle d throughth e caniste r woul d b e

-112

-I L A 

### t o > T> Q> O i i ~ 3 C L O I

d >

_ o 3 E 3 

### o 4 0

3 5

3 0

^ 5

'.0

1 0

0 FIGUR E A- 5



# CANISTE R AGIN C Ne wFor d vs . For d Durabilit y

0 > 0 4 0 Purg e Volum e (cubi c ft )P.1 6

simila r regardles s o f th e purg e ai r flowrate . However , becaus e desorptio n i s a mechanica l proces s an d th e molecule s i n refueling vapor s rang e widel yi n size , a dependenc e betwee n purg e ai r flowrat e "an d the rat e o f hydrocarbo n remova l coul d be possible . I n thi s program , a n attemp t wa s mad e t o determin e whethe r the amoun t o f H C strippe d fro ma n activate d carbo n caniste r i s a constan t functio n o f th e volume o f purg e ga s pulle d ove r the bed , independen t o f purg e ai r flowrate . Th e effec t o f purg e ai r flowrat e o n hydrocarbo n stripping wa s investigate d b yperforming thre e set s o f purg e test s o n th e Ford durabilit ycanister . Eac hse t o f test s wa s performe d unde r identica l condition s o f purge , excep t tha t th e purg e ai r flowrat e wa s differen t fo r eac hse t o f tests . Th e flowrate s chose n wer e nominall y1/2 , 1 , an d 2 cfm . Althoug hthes e value s mayb e somewha t highfo r curren t evaporativ e emissio n contro l systempurg e flowrates , i t seem s tha t flowrate s o f thi s magnitud e maybe necessaryfo r some evap/refueling contro l systems . A s note d in th e discussio n o f the caniste r weighin g procedures , the result s o f thi s serie s o f test s ha d t o b e correcte d t o accoun t fo r time spen t weighing th e canister . Fo r eac htest , i t wa s assume d tha t the caniste r wa s purge d fo r 5 5 seconds , an

d the n th e caniste r wa s disconnecte d an d weighed . Th e weighing procedur e wa s estimate d t o tak e approximatel yte n seconds . Therefore , te n second s wer e substracte d fromth e cumulativ e tota l fo r eac hcaniste r weighing . Tabl e A 3 show s the correcte d result s o f the test s use d i n th e evaluatio n o f th e effec t o f purg e rat e o n hydrocarbo n stripping (test s E l - E6) . Eac hcolum

n represent s th e averag e o f th e tw o test s don e a t the purg e rat e show n a t the to

p o f th e column . Th e result s o f the test s designe d t o evaluat e th e effect s o f purg e rat e ar e plotte d i n Figur e A6 . Eac hcurv e represent s th e averag e o f th e test s don e a t on e flowrat e a s marke d o n th e figure . I f th e rat e o f hydrocarbo n desorptio n wer e proportiona l t o purg e ai r flowrate , on e woul d expec t t o se e a patter n i n the purg e curve s i n Figur e A6 . Specifically , on e woul d expec t t o se e a steepe r purg e curve , an d possibl ya greate r working capacit yi n th e test s performe d a t th e highes t flowrate . A

n examinatio n o f Figur e A6..show s tha t no suc h patter n i s apparent . Th e curv e generate d fromresult s o f th e test s performe d using th e lowes t flowrat e fall s betwee n th e curve s o f the test s don e using th e highe r flowrates . I n addition , al l o f the test s ar e verysimila r an d th e difference s betwee n themar e certainl ywithi n th e rang e o f tes t t o tes t variability . Therefore , withi n the rang e o f purg e rate s examine d here , th e amoun t o f hydrocarbo n strippe d fromthe carbo n be d i s a functio n o f th e volume o f purg e ai r pulle d ove r th e carbo n be d an d • i s basicall yindependen t o f purg e ai r flowrate . Wha t wil l happe n a t highe r purg e rate s i s unclear .

-114

-P.1 7

TABLE A 3 CORRECTE

DAUERAG

E PURGE HISTORIE S FOR DDURABILIT

YCANISTE

R
Volum e o f Purge Ai r <ft A 3 ) 0 1 2 3 4 5 6 7 8 9 1 0 1 5 2 0 2 5 3 0 3 5 4 0 5 0 1. 0 0 14. 5 18. 2 20. 3 21. 7 22. 8 23. 6 24. 3 24. 8 25. 3 25. 7 27. 2 27. 6 28. 2 28. 6 29. 0 29. 4 30. 2 Purg e flirFlo wRat e 0. 5 0 15. 9 19. 5 22. 2 23. 6 24. 2 25. 0 25. 4 25. 6 25. 9 26. 1 27. 4 27. 8 28. 4 29. 0 29. 6 30. 1 31. 0 2. 0 0 17. 0 20. 4 21. 8 23. 3 24. 6 25. 4 26. 0 26. 5 26. 9 27. 3 29. 0 29. 8 30. 4 30. 8 31. 2 31. 5 32. 3

-115 -FIGUR E A- 6

I- " <T > 1 .— - E o >

" O o > 3 0

. Xtive o —_ 3 r-Cun 3 4

3 2 3 0 2 8 2 6 2 4

4 LX- 2 0 1 8 1 6 1 4 1 2 1 0 8 6 4 2 0 

# EFFECTO F PURG E RAT E For d Durabilit y 2 . 0
1. 0

2 0 Purg e Volum e (cubi cft ) 4 0

T l C OP.1 9

D . Temperatur e o f Purg e Caniste r temperatur e ca n effec t bot hthe loading an d stripping o f carbo n beds . Increase d temperatur e i s equivalen t t o a n increas e i n the kineti c energyo f the molecule s i n th e gas . An increas e i n the kineti c energyo f ai r an d hydrocarbon s associate d wit ha temperatur e increas e i n a n activate d carbo n be d shoul d eaus e a decreas e i n th e amoun t o f hydrocarbo n adsorbe d bu t shoul d als o ai d the desorptio n process . Thi s tes t progra mwa s focuse d o n the proces s o f purging hydrocarbon s from a carbo n bed , an d therefor e th e temperature/loadin g interaction s ar e no t addressed . Th e effec t o f caniste r temperatur e o n purg e wa s tangentiall yinvestigated , however . Fourtee n test s wer e performe d o n the newFor d canister . I n the firs t si xtests , bot hthe caniste r ambien t an d purg e ai r temperature s wer e maintaine d a t 95°F . I n the thirteent han d fourteent htests , the caniste r ambien t an d purg e ai r temperatur e wer e hel d a t 75° . Figur e A 7 show s two plots ; on e representing the averag e o f the result s o f the test s i n whic h canister s wer e purge d at 95° , the othe r representing th e test s using a 75 ° purge . Fromth e graphi t appear s tha t temperatur e ha s a distinc t effec t o n purge . Ther e ar e circumstance s o f th e testing , however , whic hsugges t tha t the result s maybe confounded . A s mentione d above , the test s i n whic hthe caniste r wa s purge d a t 95 ° wer e th e firs t si xtest s don e o n th e newcanister . Th e test s i n whic hthe caniste r wa s purge d a t 75 ° wer e th e 13t han d 14t htest s performe d o n tha t canister . Althoughi t i s expecte d tha t extensiv e agin g woul d no t be observe d afte r a limite d numbe r o f cycles , an yagin g effect s woul d bia s th e result s o f thes e test s toward th e patter n observe d i n Figur e A7 . Althoughther e i s a possibilit ytha t the result s o f thes e test s mayb e somewha t confounde d b yaging effects , i t appear s tha t th e increase d purg e temperatur e di d hav e some effec t o n th e amoun t o f hydrocarbo n tha t wa s strippe d from th e caniste r b

ya give n volum e o f purg e air . E . Representativ e Curve s A s wa s state d previously , th e mai n . goa l o f thi s tes t programwa s t o evaluat e the purg e respons e characteristic s o f severa l activate d carbo n canister s whe n loade d wit hrefueling vapors . Thi s wa s don e b yloading eac hcaniste r t o o r nea r the breakthroughpoin t wit hrefueling vapors , an d the n pulling hydrocarbon-poo r ai r ove r th e activate d carbo n be d an d monitoring th e caniste r mas s chang e a s a functio n o f purg e ai r flow . Th e purg e ai r flowrat e an d temperatur e o f purg e wer e generall yhel d a t 1. 0 cf man d 95°F , respectively , during th e

-117

-FIGUR E A- 7 

# EFFECT S O F TEMPERATUR E

7 5 de g vs . 9 5 de g

i I- 1 OO I it> E O i « — ' X> a > o > i

_ 3 Q

_ O I a > > 3 E 3 

### u

Purg e VOLUM E (cubi cft )'.2 1 caniste r purg e sequences. * Averag e curve s wer e the n generate d fo r eac hcanister . Th e averag e curve s fo r th e fou r eva p canister s fro

mdurabilit yvehicle s ar e show n i n Figur e A8 . Figur e A 9 show s the

- curv e fo r th e EPAcanister , whic hwa s designe d an

d buil t a s a refueling caniste r an d ha s a workin g capacit ymuc hlarge r than th e evaporativ e caniste r capacities . Th e plot s o f the averag e curve s ar e valuabl e i n tha t som e understanding o f the difference s i n the purg e respons e o f th e variou s canister s (a s measure d b ythe difference s i n the shape s o f the variou s curves ) can be gained . I t i s difficul t t o us e the curve s t o full yevaluat e the performanc e o f th e variou s canister s however , becaus e some o f th e difference s ar e simpl y du e t o the fac t tha t th e canister s ar e no t al l o f on e size . Althoughther e ar e severa l variable s othe r than siz e tha t ma y affec t the performanc e o f the canister s (carbo n type , shape , an d interio r configuration , t o mentio n a few) , thi s programwa s no t designe d t o investigat e th e effect s o f the difference s i n caniste r designs . Th e difference s i n the curve s du e onl yt o difference s i n siz e can b e effectivel yeliminated , however . Th e difference s i n caniste r size s wer e eliminate d b y normalizing the averag e curve s presente d i n Figure s A 8 an d A 9 b ycaniste r volume . I n scaling th e caniste r curves , th e characteristi c shap e o f eac hcurv e wa s preserved , bu t th e purg e curve s wer e scale d t o represen t the result s expecte d fo r a on e lite r canister . Th e normalizatio n wa s don e b ydividing th e X an d Y component s o f the point s o n th e averag e curv e b yth e caniste r volume (i n liters) . Th e us e o f thi s scaling techniqu e implicitl yassume s tha t a smal l caniste r designe d exactl ylik e a larg e caniste r (i n term s o f lengt ht o diamete r ratio , interio r configurations , carbo n base , etc. ) woul d demonstrat e stripping characteristic s (fo r equivalen t amount s o f activate d carbon ) identica l t o thos e o f th e larg e canister . Fo r example , a half-size d caniste r purge d hal f a s muc hwoul d releas e hal f th e hydrocarbon s tha t a ful l size d caniste r would . Th e volume-normalize d purg e curve s ar e show n i n Figur e A10 . Th e curve s ar e labele d wit hth e sourc e (or supplier ) o f th e caniste r a s wel l a s wit hth e bas e materia l use d i n th e productio n o f th e activate d carbon . Severa l feature s o f Figur e A1 0 ar e worth

yo f discussion . Th e firs t thing tha t i s noticeabl e i n Figur e A1 0 i s tha t th e curv e generate d fromth e Thre e purg e rate s wer e use d i n the test s o n th e For d durabilit ycanister , bu t a s discusse d in th e sectio n o n th e effect s o f purg e rate , thi s had littl e impac t o n th e results .

-119

-FIGUR E A- 8 

# DURABILITYCANISTER S

AVERAG E CURVE S

i 

### E o i E

0 1

• o a > o > 3 Q . O I a> >
3 E 3 

### o

Purg e Volum e (cubi cft )FIGUR E A- 9

1 M21- ( 0 

## E o > « * T Jurge Q
_ O Itive

c s 3Cum 17 0 16 0 15 0 14 0 13 0 12 0 11 0 10 0 9 0 8 0 7 0 6 0 5 0 4 0 3 0 2 0 1 0 0 

# EPACANISTE R Averag e Curv e

^L.

2 0 4 0

Purg e Volum e (cubi cft )

C OFIGUR E A-1 0

a >

I M t o t o I \ t n E o *— ' a > O i k

_ 3 Q

_ 4 > > •*-• O 3 

### t 3 

### o 4 0

3 5
3 0

2 5

2 0

1 5

1 0 

# REPRESENTATIV E CURVE S Normalize d b yCaniste rVolum e

0 -j 0 1 0 2 0 Purg e Volum e (cubi c feet/liter ) 3 0result s o f the test s o n the Chrysle r caniste r i s isolate d from

the res t o f the curves . A n examinatio n o f th e informatio n o n canister s presente d i n Tabl e A l reveal s nothing extraordinar y abou t the Chrysle r canister . Th e activate d carbo n use d i n thi s caniste r an

d th e caniste r constructio n appea r verysimila r t o the materia l an

d constructio n o f th e othe r canister s teste d i n thi s program . Chrysle r wa s unabl e t o provid e informatio n o n the history , o f the canister , an d ther e mayhav e bee n some unusua l treatmen t o f the caniste r whic hlead t o thes e unexpecte d results . Althoughno explanatio n fo r th e performanc e o f the Chrysle r caniste r i s apparent , i t i s clea r tha t the result s o f th e test s o n thi s caniste r fal l wel l outsid e o f the rang e predicte d b yth e test s o f the othe r canisters . Becaus e th e result s o f th e test s o n th e Chrysle r caniste r canno t b e explaine d b yth e informatio n availabl e t o EPA , th e curv e fo r the Chrysle r caniste r wil l no t b e include d i n an yfurthe r analysi s o f th e results . Th e mai n featur e o f interes t i n Figur e A1 0 i s tha t i t show s th e difference s i n th e purg e respons e characteristic s o f similarl ysize d canister s o f severa l designs . Th e Nissa n caniste r apparentl yrelease s hydrocarbon s relativel ygrudgingl y during th e initia l stage s o f purge , bu t show s a les s drasti c deca yo f hydrocarbo n stripping a s the purg e proces s continues . Th e For d caniste r lies ' a t th e opposit e en d o f th e purg e respons e spectrum . Thi s caniste r typ e apparentl ygive s littl e resistanc e t o hydrocarbo n remova l during the initia l stage s o f purge , bu t the hydrocarbo n stripping rat e drop s quit e rapidl y thereafter . Th e othe r two curve s (the G . M . an d EP Acurves ) fal l withi n thes e extremes . Als o show

n i n Figur e A1 0 i s th e typ e o f carbo n use d i n eac ho f th e canister s tested . Looking a t th e righ t sid e o f Figur e A1 0 i t appear s ther e migh t b e a distinc t purg e curv e fo r eac hcarbo n type . Upo n examining the lef t sid e o f th e figure , however , i t ca n b e see n tha t th e For d (coa l base ) an d EPA (wood ) curve s ar e almos t identica l throughth e earl ystage s o f purge . Th e Nissa n curv e i s distinc t throughou t it s purg e history , however , an d ther e ma yb e some difference s i n th e fundamenta l absorption/desorptio n characteristic s o f coconu t base d carbons . Th e compariso n o f purg e curve s b ycarbo n typ e shoul d no t be emphasized , however , becaus e ther e ar e severa l othe r variable s i n caniste r design tha t coul d no t b e separate d fro mcarbo n typ e b

ythi s experimenta l design . F . . Caniste r Temperatur e During Purg e Th e caniste r liste d i n Tabl e A l unde r "EPA " wa s designe d an d buil t fo r refueling emissio n contro l tests . Whe n thi s caniste r wa s loade d wit hactivate d carbon , a thermocoupl e wa s installe d i n th e caniste r s o tha t interna l caniste r

-123

-temperature s coul d b e measure d a s needed . The thermocoupl e wa s

use d t o monito r interna l caniste r temperatur e during tw o o f th e purg e sequence s don e o n th e refueling canister . Th e trac e o f caniste r temperatur e a s a functio n o f th e volume o f purg e ai r pulle d throughth e caniste r fo r on e o f thes e test s i s show n in Figur e All . A s can be see n fromth e trace , th e desorptio n proces s absorb s heat . Th e temperatur e o f the caniste r drop s fromit s peak (measure d a t 135° F immediatel y afte r loading ) dow n t o it s lowpoin t (70°F , 6° F belo wth e ambient ) i n unde r 1 0 minutes . Th e caniste r temperatur e the n climb s bac k t o the ambien t in abou t te n minute s an d remain s nea r th e ambien t throughou t the remainde r o f th e purge . Thi s informatio n i s significan t fo r two reasons . First , a s hydrocarbo n i s strippe d fro m the canister , th e temperatur e o f th e caniste r fall s rapidly . Th e decreas e i n temperatur e coul d ten

d t o inhibi t the remova l o f mor e hydrocarbons . Second , a s note d above , the caniste r temperatur e ca n fal l belo w the ambien t during the purg e an d i n certai n situation s th e interna l caniste r temperatur e coul d fal l belo wth e dewpoin t resulting i n condensatio n insid e th e canister . Althoug hthi s situatio n woul d probabl yno t aris e wit han yregularity , condensatio n insid e the caniste r coul d occasionall yoccur . G . Conclusion s A s state d in th e introductio n t o thi s paper , thi s tes t progra mhad on e primarygoa l an d severa l secondarygoals . Th e primarygoa l o f the progra mwa s t o evaluat e th e purg e respons e characteristic s o f severa l canister s o f differen t designs . Par t o f thi s evaluatio n wa s th e developmen t o f "purg e curves " whic hcoul d b e use d i n th e developmen t o f a procedur e fo r evaluating the purg e capabilit yo f onboar d refueling emissio n contro l systems . Th e secondarygoal s o f th e programwer e t o investigat e th e effect s o f aging , purg e ai r flowrat e an d purg e ai r temperatur e o hhydrocarbo n stripping characteristics . I n th e cours e o f gathering dat a t o addres s th e topic s mentione d above , informatio n wa s als o obtaine d o n interna l caniste r temperature s during th e purg e process . Althoug hthi s tes t programha d a limite d scop e severa l usefu l conclusion s ca n stil l b e draw

n fromth e data . Th e conclusion s tha t ca n b e drawn concerning th e secondarygoal s o f th e programwer e state d a s par t o f th e analysi s o f results . Th e result s o f th e test s t o develo p representativ e curve s for th e variou s canister s meri t some furthe r discussion , however . Th e remainde r o f thi s sectio n describe s th e manne r i n whic hth e representativ e curve s ca n b e

-124

-FIGUR E A-1 1



### 1 4 0

t o I W •V
T 3 U J D C Z > I - < Q C U I C L 2 u i 

# CANISTE R TEMPERATURE S DURIN G PURG E

10 0 TIM E (min )use d i n the developmen t o f a refueling tes t procedure , and som e

recommendation s fo r improvement s i n the experimenta l desig n use d i n thi s program . Ates t procedur e designe d t o evaluat e th e effectivenes s o f onboar d contro l system s mus t tes t the abilit yo f th e syste mt o provid e capacit yfo r th e storag e o f refueling emissions . I n the cas e o f
_

a systemtha t use s activate d carbo n a s the storag e mediu m(whichi s expecte d t o be th e case) , thi s involve s stripping hydrocarbon s fro m the activate d carbo n be d b ypullin g hydrocarbo n poo r ai r acros s it . Abasi c understanding o f th e relationshi p betwee n hydrocarbo n stripping an d purg e ai r flo w i s neede d i n orde r t o develop a procedur e whic hadequatel y test s the purg e capabilit yo f the contro l system . Th e mai n purpos e o f thi s tes t programwa s t o develop a serie s o f purg e curve s whic hcoul d be use d t o represen t th e rang e o f purg e respons e pattern s tha t coul d b e expecte d o f onboar d contro l systemcanisters . Th e representativ e purg e curve s develope d i n thi s program ar e show

n i n Figur e A10 . Thes e curve s represen t the expecte d performanc e o f on e lite r canister s o f the same desig n a s thos e use d i n th e tes t program . A s discusse d i n th e analysi s o f data , the curv e fo r the Chrysle r caniste r fall s wel l outsid e o f the rang e o f curve s generate d fro mthe dat a fromth e othe r canisters . Sinc e ther e i s no evidenc e t o sugges t tha t th e Chrysle r caniste r i s radicall ydifferen t fromth e othe r canister s i n term s o f materia l or design , th e curv e generate d fo r thi s caniste r i s probabl yno t representativ e o f thi s canister' s typica l performance . Th e remaining curve s fal l withi n a relativel ynarro wband i n Figur e A10 . Althoughthe curve s ar e closel ygroupe d spatially , ther e ar e significan t functiona l difference s acros s th e curve s i n tha t range . Th e curv e representing th e performanc e o f the For d caniste r rise s quit e sharpl yan d show s a relativel yclea r breakpoin t earl yi n th e purg e proces s afte r whic hth e curv e flatten s out . Th e curv e generate d fromtest s o n th e Nissa n caniste r i s les s steep i n th e initia l stage s o f purg e an

d tend s t o brea k ove r mor e gradually . Th e curve s fo r the For d an

d Nissa n canister s ar e th e mos t dissimila r o f thos e i n Figur e A1 0 (excluding th e Chrysle r curve) . Becaus e thes e curve s ar e th e mos t dissimilar , the yca n b e use d t o represen t the rang e o f respons e pattern s expecte d fromactivate d carbo n canisters . Therefore , thes e two curve s wer e use d i n the analysi s performe d i n th e developmen t o f the refueling tes t procedure .

-126

-P.2 9 Reference s 1 . "Refueling Emission s fro mUncontrolle d Vehicles, " D . Rothma n an

d R . Johnson , EPA-AA-SDSB-85-6 , U.S . EPA , OAR , OMS , ECTD , July , 1985 . 2 . "Draf t Recommende d Tes t Procedur e fo r th e Measuremen t
_

o f Refueling Emissions, " L.D . Snapp , EPA-AA-SDSB-85-5 , U.S . EPA , OAR , OMS , ECTD , Jul y1985 . 3 . "Subpar t C - Emissio n Regulation s for 19X Xan d Late r Mode l Yea r Newo r In-Us e Light-Dut yVehicle s an d Ne wo r In-Us e Light-Dut yTrucks ; Refueling Emission s Tes t Procedure, " Draft , U.S . EPA , OAR , OMS , ECTD , Jul y1985 . 4 . "Summaryan d Analysi s o f Dat a FromGasolin e Temperatur e SurveyConducte d b yAmerica n Petroleu mInstitute, " Radia n Corporation , Ma y1976 . 5 . "A

n Assessmen t o f EPA' s Certificatio n Procedur e fo r Onboar d Refueling Emissio n Contro l Systems, " Technica l not e prepare d fo r America n Petroleu mInstitut e b

yRober t Kausmiez , Radia n Corporation , February19 , 1986 . 6 . "Fue l Volatilit yTrend, " Fina l Report , Lette r from Bruc e B.Bykowski , Southwes t Researc hInstitut e t o Crai g Harve y an d Am yBrochu , U.S . EPA , Septembe r 28 , 1984 .

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-