p.1 

OAR Box 1147 

Prepped by Ollie Stewart 

Document Number: 

187) IV-E-61 

Docket Number: 

A-87-11 

Printed 4/22/2008 2:42:57 PM Sheet 187 of 242 
TT 

P.2 

A-67-24 

^m 

21 /JM 

• 'if 

•

 r'sVV!>;=iif,':-»»." .-•••:• ' • • •..'-••'• .-, .. 

-..•rt.:,;•-.•so.tf-»vr. '• -.-.•;. 7'.. . f..- v-3£ .^r -

-r-7'^V'««*c.>.r.'s- . .:•-••••;. .. :' < V " ••jrt! .,>i :v ;~^» 

' -" •-a/'l.-fjl - .rv. v .:.••-:•• •}• ^$->;?-.»£i"' 

a

i

.-~*':^l'-&:pir:Yt. ''>- "A' •• "' '. '•,; •" V,*7 \ SsW 

"•'»: ' !*rKy ' '.yr':-.. 

<r'»;

'

::' " : ii^-' ••:•' t^;7J: « 

••'•'"'••• '.: '• .V.-;VA.7 ; ,.-*.-*«•<,*»r •;?:<;*?&-£ 

•..•••••• '•. ~m-*r- ? -^.Kfy* • •''V*>rriiJ.: 

vHRfldRASDOH 

SWECTr sote#^|rro»sf Public workshop 

FROM: 

...>': ~\$Ariu-.:. 

r TO! 

:

*?ii5 i Sftlpn* jf t<*f:. 

Evaporative •••rv*.. and Refueling Emissions' Tes 

for the Control of Excess Evapocetive Raiestoha" 

Tad Wyaor, Mechanical. gngln<B#'fcvT:.-;.. A'A v^^^l i 

Standards. Development and Support^BrancK^i^^^V ^•^•.1?-.,<i 

- •'-•••7. . -, . ••..••. • - - -vs-•„•»•.••:•'••':'-SR --vr^r. . cw^WWi/ * :*»s?«>r - •; " ~ ' 

Docket A-85-21 

THRO: Richard Ai; ^JcoWkly:; Senior. Project Manager 

Standards ^Dev'elbp>«ffnt and Support Branch 

On June 30, 1988, EPA held a public workshop at ite Ann 

Arbor, Michigan, Motor Vehicle Emission Laboratory. In a 

morning session, EPA made oeveral presentations. During the 

afternoon, presentations were made by representatives of the 

Motor Vehicle Manufacturer's Association (MVMA). 

The EPA presentations consisted cf: 1) an analysis cf 

temperatures on high-ozone days, 2) descriptions of suggested 

test procedure changes which may later be proposed for vehicles 

equipped with integrated and non-integrated refueling systems, 

3) an overview of EPA's model and the assumptions used to 

evaporative and refueling emission control systen 

performance under test and in-use conditions. Notes from these 

presentations and an attendance list are attached. 

3nd 

rredict 

The presentations by MVMA members-were 1) an analysis of 

the effect of certain aspects of canister size and performance 

on evaporative eaissions, 2) the effect of RVP and local 

clisiate on fuel boiling, and 3) detailed cowmen ts on EPA's 

onboard refueling test procedure. MVMA will sutmit material 

relating to these presentations separately to this docket in 

the near future. In addition, copies of a verbatln transcript 

will be available for purchase through MVMA in about one month 

(contact Greg Walker at (313) 872-4311). 

Attachments 
P.3 

Agenda 

Modifications to Evaporative and Refueling 

Emissions Test Procedures for the Control 

of Excess Evaporative Emissions 

June 30, 1988 

Ann Arbor, Michigan 

I. Opening Remarks (9:30 a.m.): Richard Wilson 

II. Integrated System Test Procedures (9:45 a.m.) 

A. Simplified Evap/Refueling Procedures: John Anderson 

B. Revisions to Address Excess Evaporative Emissions: 

John Anderson 

III. Non-Integrated System Test Procedures (10:15 a.m.) 

A. Revisions to Achieve In-Use Performance of 

Integrated Systems: Richard Rykowski 

B. Revisions if Onboard Controls Were Not Promulgated: 

Richard Rykowski 

IV. Discussion (10:45 a.m.) 

IV. Presentations by Manufacturers on Onboard Test Procedures 

(1:00 p.m.) 

V. General Questions and Answers (4:00 p.m.) 
P.4 

Modifications to Evaporative and He fuel ino; 

Emissions Test Procedures for the Control 

of Excess Evaporative Emissions 

SIGN IM SHEET FOR ATTENDEES 

N 

N-A »*l OrU Jt SAiiru 

rfr&r*jJ4*-Um<?6Am tf 

Lach 

y>LTZ2?M/T 

Cttflr-ei. ^i_y-J*> 

UrOKJAZD W. it AT A 

Qi\Atmr<-rt {sU^^cl-^rT^CrrJ 

4/A/#ft GoRiS 

L 

TMfTSUM^rfl 

$.T(<\AM 

/P^AA /^mr^m.**-^ 

£d idcxuj iCur-y 

Company 

C/t^y rfs^u- tUotOr-imS. 

dTAVl/A 

Au. ii 

cST>w Co* 

G.IM 

(LmZUrys -Attr- J^c^tcvr-j 

Fo/z.)^ 

^ r-f \ )<• 

CL.ys/r* 

C~-m\ A» > KjeSQO/llt-r BQCAfCA 

mCoH, r. O IL, 

VoU&ooA66rO or DMeCiat, Ixlc -

cCtei/j&l fM 

L^^Cr i&rJc 

AJ. #T^a-»^,W r>ur 

rn-Y^t 

(^^TM^H 

Mti^&A 

£4'*SjZlr4r^jtr&Z< g TmmA^mtr L 

6.1 
P.5 

Modifications to Evaporative and Refueling 

Emissions Test Procedures for the Control 

of Excess Evaporative Emissions 

SIGN IN SHEET FOR ATTENDEES 

UP fk'S/.^sJ 

AA\ ) CMt-mtlmJL LtQlAm-J-j O^C^O 

/ 

-irUjmrrmX^ 

Ci 

£l< r^ZUl/ 

7ALL rm-B^r ^ 

OCJ/3 /\c&/U4SA? 

Company 

m. 

A>M 

Gh\ 

l) fi MCltrlS2>e>4 *S2c4 

«• t^rmm* 

G^ 

Gm.^ 

4 

& 

LJ-M 

/^C^JL 

K, <- » 4 

/)//!£/*• /?AJrO- //5S/V'. 

£A. 

G-ifA 

—^^5 h 

/k7?OrVr-*mC-/rV±AlS ^ 

{/tr-j^r-zf . 

(/J-evU/c-c^ 

^cyxz.s^VYe 

Mimry A>tffS€m, Oijtf - Er-j - P.9J . 
P.6 

Modifications to Evaporative and Refuelino; 

Emissions Test Procedures for the Control 

of Excess Evaporative Emissions 

SIGN IN SHEET FOR ATTENDEES 

N 

SA Lmm-y (2/*?tA-erl\? 

<g^y rA4/Jc/-/£r?z 

"7* y^ 

//gy/ MO. 

t-^tlc 

Qt-ne. 

#?* '4 ^V 

^ f^ Ak ^STl' 

JO&J r,J( tax *A 

A/mJi/ M <LdJ^llyy; 

Company 

~-\\W\ 

//mf--' A-m^y /PCATSAM OT-fCAttC' 

c <mA W-v. ^"^ \ H -* 

A*/'" TS-*~ J?) -~^-r< " 

/ f r A* STl-mmm? /^V , 

[U* tr^-C-^AA * A S -TO Cm 

AfZL 

^r-^ 

ah So* 6?l '1*4 T Vl/t <Z tr-! -~\ 
P.7 

Modifications to Evaporative and Re fuel ino; 

Emissions Test'Procedures for the Control 

of Excess Evaporative Emissions 

SIGN IN SHEET FOR ATTENDEES 

Naae" Company 

%.\\ VlAc-peo r<W>fc* 3.A0O 
P.8 

Modifications to Evaporative and Refueling 

Emissions Test Procedures for the Control 

of Excess Evaporative Emissions 

SIGN IN SHEET FOR ATTENDEES 

M. rt\£V*g 

A^Aftl-

\Ai^A\ 

p'CLuj' /rfyiiftArfc S> n 

/WrLrtrrrUmtoLlrA 

iUCLi/'ol 

Company 

L^Ajtry&6\y\ • 

<kH 

ft?/v> 

^te ^ lO^TQmmm 

ft/Hi 

T>g"*<?7. 

MS^/?— 

AV/vZ/t/A 

MAL 

f=?6/& 

n 

fi 

f^m-r Rib U.S./) 

AA-0(!^( Y /hier/OL fa Q 
P.9 

Modifications to Evaporative and Refueling 

Emissions Test Procedures for the Control 

of Excess Evaporative Emissions 

SIGN IN SHEET FOR ATTENDEES 

^g/\(H \p_ t> kx ^ 

\Pm Cg/coU_ _ 

'/j/ t tj dXv ^ (M^tr-mZ-r-r-- : 

V/Mmm** 

$(- /S'TFA/tre 

M. {Mo 

A?*T£AA, 

^DJOlOf c &> 

I^^Sg^ 

^M 

t 

u-j-ePA Q£D 

V/U ^ Ar 

F O ^ r>, Or. c 

Mfift \E£IAI ces: 

\W^a\an 

VUnrVil-\-on 

S ^AM-T 

^&uAr? <&e 

We 8 4, Q>p r 

ML. 

<M<V 

yt*mm 

A ^>t-<^-gg> <£?'/4, 

Ct-rfV/S LtfR 
P. 10 

Modifications to Evaporative and Refueling 

Emissions Test Procedures for the Control 

of Excess Evaporative Emissions 

SIGN IN SHEET FOR ATTENDEES 

.<[dt. /oK^r'stS 

^s-^Kl VOL ^ s.T 

\m/ < l^/ ' f-lfrr-Amr<?*•£-£• - » 

WrmTrldr+mffl C 

Cz7Z£& \^/tfZrTZ>/sJ 

\Jj4trt IdUtniCi^ 

*OY~y<L K Us<;/£s*-

fyr^iVc/$fa«Jl -7 

JjL-m. O'fon 

HU^L 1) CA > ' 

TA^CBSA I H Ai-rcLAp/-\ 

^ITfe ism^o 

V- #K4H/A 

fcl 6r\60DCrL 

UJlLH£tMr /-ftA,cCA_ 

Company 

_Qh_ 

fZ^cJ 

CK\ 

jCL^tALlA 

MJ&Xfi ^Jb 

ATU 

5UAJ //W 

SxjftaJ 'USA 

^Acyrc\ fc-rzz^c»-<r~C 

AC 

<AA r i"rOr~7 /fy $ rof-c ^ Cd 

i^--rt ISmJ ^LA=.0^<rfi--' 

^FSmr-rr^tr-l . J ~ j^ f /^ 9 

AH £ /? iCAlfsj HO Ami PA 

~T£?S>D TA 

CrMfiieU 

£^£i O 

/iStfrAs^ 

TcfAorA 

& MA./ 
P.11 

Public Workshop 

Excess Evaporative Emissions and Test Procedures 

United States Environmental Protection Agency 

Ann Arbor, Michigan 

June 30, 1988 

Temperatures on High Ozone Days 

Mark A. Wolcott 

U.S. Environmental Protection Agency 

Dennis F. Kahlbaum 

Computer Sciences Corporation 
P.12 

Analysis of Temperatures 

on High Ozone Days 

Data Sources 

1984 National Weather Service Data 

1984 AIRS Ozone Data 

1985-1987 Design Value Monitors 
P.13 

1984 National Weather Service Data 

Diurnal Temperature = 

Maximum - Minimum Daily Temperature 

1984 AIRS Ozone Data 

Design Value Monitors 

From 42 Out of 68 CMSAs 

Exceeding the Ozone NAAQS 

During 1985-1987 
Average Maximum 

Daily One Hour Ozone 

12.0-26.0 (pphm) 

Mean = 13.7 (pphm) 

Average Maximum 

Daily Temperature 

45.0°F-111.0°F 

Mean = 90.6 °F 
Average Diurnal Temperature 

7.0°F-41.0°F 

Mean = 24.8 °F 

Group by ASTM Class 

Rank by Maximum Daily Temperature 

Select 90th Percentile 
Class A Cities 

Maximum Daily One Hour Ozone 

Top 10 Percent 

14.2 (pphm) 

Class A Cities 

Maximum Daily Temperature 

Top 10 Percent 

104 °F 
Class A Cities 

Diurnal Temperature 

Top 10 Percent 

23 °F 

Class B Cities 

Maximum Daily One Hour Ozone 

Top 10 Percent 

12.0-15.0 (pphm) 

Mean = 12.5 (pphm) 
Class B Cities 

Maximum Daily Temperature 

Top 10 Percent 

105.0 °F-109.0 °F 

Mean = 106.7 °F 

Class B Cities 

Diurnal Temperature 

Top 10 Percent 

26.0 °F-37.0 °F 

Mean = 31.7 °F 
P.19 

Class C Cities 

Maximum Daily One Hour Ozone 

Top 10 Percent 

12.0-24.4 (pphm) 

Mean = 15.0 (pphm) 

Class C Cities 

Maximum Daily Temperature 

Top 10 Percent 

94.0 °F - 99.0 °F 

Mean = 95.8 °F 
P.20 

Class C Cities 

Diurnal Temperature 

Top 10 Percent 

22.0 °F - 35.0 °F 

Mean = 25.3 °F 
P.21 

Public Workshop 

Modifications to Evaporative and Refueling 

Test Procedures for the 

Control of Excess Evaporative 

Emissions 

Standards Development and Support Branch 

Emission Control Technology Division 

Office of Mobile Sources 

June 30, 1988 
P.22 

Outline 

Test procedures for integrated refueling control systems 

Simplified evap/refueling procedure 

Revised procedures to address excess evap emissions 

Test procedures for non-integrated systems 

Modified evap procedures to provide the same in-use 

performanmce as integrated systems 

Revised evap-only procedures if onboard controls are 

not promulgated 
Test Procedures for 

Integrated Refueling Control Systems 
NPRM Test Procedure 

Separate refueling and exhaust/evap sequences (See Fig. 1) 

Increased testing burden and complexity was noted in 

numerous comments 

Running losses could be partially controlled 

No guarantee running losses will be routed to engine 

or canister 

If routed to engine, running losses could overwhelm 

low purge systems 
REFUELING TEST PROCEDURE 

(AUGUST 19, 1987) 

• DrafeFMTae* 

• SoekVeMote tor •Hoore 

• E M to MED to I 

Integrated Sysiem 

a. Disconnect Vapor Une to Canister 

b. Drain Fuel Tank 

c. 40% Fueling 

d. Reconnect Vapor Une to Canister 

e. Drive One LA-4 

I. One Hour Hot Soak 

g. Repeat (a) and (0 Twice 

h. Disconnect Vapor Una lo Canister 

I. Drain Fuel Tank 

|. 40% Fueling 

k. Reconnect Vapor Una lo Canister 

L Haal Build (60* • 2*F Initial, 

24* •» 1'F Rlae) 

m. Repeal (a) Through (0 Twtoa 

n. Drive One LA-4 

T 

, w ^ 

EMt0rSt#Q SyWMR 

Cjnjmf Purai. Congniinm nrtw 

a. Dtecormart Vapor Una lo Canister 

h. Drain Fuel Tank 

o.40%Fuelng 

al Raeonrtacl Vapor Una la Canister 

a. DHva Bspsated LA-4a Uatil I 

Pvrrjt Eejutvatenl to Cycle Drive. 

Mleeoe AoouHMdatioe) fltooo al lia 

FlretMePaettitol 

1 

NonHnlt^QfslBv System 

Canister Purge. CanMnuoua Drive 

b. Onto Fual Tank 

o. 19% FualnQ 

d. Raconnacl Vapor Una to Canister 

a. Mvo Repeated LA-4a Until 

W% ol Tank Votuma la Consumed 

* RtOOMMCt VeMQf 

* FueHoAuteaMtic 

Bootort Fusing, ralaikej Any 

WhMn 18 
EVAPORATIVE AND TAILPIPE PROCEDURE (FTP> 

(AUGUST 19, 1987) 

P.26 

:-L-

[ 

C Start J 

Orain Fuel Tank ] 

| Vehicle Temperature Stabilization (aa required)! 

| Load Canistera To Breakthrough | 

DSOONNECT REFUEUNQ CANISTER 

CONNECT RERJEUNQ CANISTER 

| Fuel Drain & Fill | 

i 

DBCONNECT REFUELING CANISTER 

| Dyno Preconditioning | 

—I Cold Soak Parking l " 

fDieeell 

l^OnlyJ 

CONNECT REFUEUNQ CANISTER« 

Fueing 

* Drain 

• 40% Fin 

Diurnal Heat Build 

* Heat Fuel • 1 Hour 

• 60-84' F 

Evap. Test 

NotReq. 

I 

Diurnal 

Enclosure 

Test 

Cold Start Exhaust Test 

Evap. Test 

Not 

Performed 

- • f 

nv/rtunning 

Losses as Required 

Hot Start Exhaust Test I 

Hot Soak 

Enclosure 

Test 

I 

I 

? 

CZ3 

1 hour MAX 

•5 min. MAX 

0*1 hr 

12-36 hrs 

(no MAX 

for diesels) 

I 10 min. 

HZ3 7 min. MAX 
P.27 

Simplified Integrated Test Procedure 

0 Basic" modification for refueling/evap testing (See 

Figure 2) 

Conduct refueling test after exhaust/evap FTP 

Rely on exhaust/evap sequence to test ability to 

purge canister 

Excess evap emissions will be addressed later 

0 Primary effects 

Less cert, testing burden, simplified procedure 

No vehicle cost increase and same in-use performance 

compared to NPRM procedure for most systems (See 

Table 1) 

0 Provides substantial, but not complete control of evap 

emissions on high-ozone days 
P.28 

REFUELING TEST PROCEDURE: 

INTEGRATED SYSTEMS 

FTP 

T 

EPA URBAN 

DYNAMOMETER 

DRIVING SCHEDULE 

I 

I IS min. MAX 

DISCONNECT REFUELING 

CANISTER 

I 

I 3 mis. MAX 

REMOVE FUEL FILLER CAP. 

DRAIN FUEL TANK. 

I 8 to 24 Hour* 

VEHICLE TEMPERATURE STABILIZATION 

I 

! • « FUELING (Sl-SVF FUEL) 

I 

CONNECT REFUELING CANISTER 

I 

PLACE VEHICLE IN SHED 

I 

.1 

I 3 Hours MAX 

MEASURE REFUELING 

EMISSIONS 
P.29 

Table 1 

Canister Volumes Required to Comply 

with Various Test Procedures 

Integrated Onboard Systems 

n 

Charcoal Type: 

Purge Rate: 

Test Sequence 

NPRM 

FTP+Ref 

FTP+LA-4+Ref 

FTP(High Temp DiurnaD+Ref 

FTP/Di/Ref 

Ford 

High 

4.4 

4.2 

4.1 

4.2 

S.S 

Canister Sized) 

Nissan 

Low Hiflh Low 

5.3 4.4 9.4 

* 

5.1 4.8 18.5 

5.1 4.1 9.7 

5.2 4.9 »2 0 

6.6 6.9 »2 0 

Notes: 

1) FTP = LA-4+Diurnal+3-Bag Test+Hot Soak 

2) Purge Rates: High = 20 ft3/LA-4, low = 8 ft3/LA-4 

3) Fuel tank size = 17.6 gallons 

4) Design refueling capacity = 90.0 g (85% fill) 
P.30 

ifications to Address Excess Evap Emissions 

Excess evaporative emissions 

Popping and hissing 

Running losses 

Related safety issue: fuel spurting 

Goals 

Eliminate fuel spurting, popping and hissing 

Running losses routed to engine (if in a purging 

mode) or canister and not vented 

Test procedure revisions 

Engineering evaluation of system design 

Remove gas cap in SHED immediately after exhaust test 
P.31 

Engineering evaluation 

- Goal to ensure fuel tank vapor is never vented to 

the atmosphere under any in-use conditions, except 

under extraordinary circumstances 

Key design parameters: limiting orifices, vapor 

routing, relief valves in gas cap or elsewhere 

Gas cap removal 

Easy to perform 

No projected effect on hot-soak emissions if tank 

pressure build-up is avoided or pressure is released 

to canister as gas cap is released 

Prevents fuel spurting, popping and hissing upon 

refueling 
Test Procedures for 

Non-Integrated Systems 
P.33 

0 

NPRM Procedures 

Entirely separate refueling and evap/exhaust test sequences 

No excess canister capacity required to enable control of 

excess evap emissions 

Required evap canister purge rates could be overwhelmed by 

in-use running losses 

NPRM procedure provides an inappropriate incentive toward 

non-integrated systems 

Goal of revised procedure: ensure equivalent control of 

in-use evaporative emissions with both integrated and 

non-integrated procedures 
P.34 

Revised Non-Integrated Test Sequences 

Basic modifications 

Leave refueling procedure alone 

- Enhance evap control capability by adding two 

representative diurnals at end of the current 

evap/exhaust test sequence (See Figure 3) 

Address fuel spurting, popping, hissing and running 

losses in same way as for integrated systems 

In-use performance equivalent to integrated systems 

essentially requires that the evap canister be as large as 

an integrated canister with same purge rate (See Table 2) 

Two representative diurnals are roughly equivalent 

to a single 85% refueling 

At least 16% of LDVs and LDTs experience multiple 

uninterrupted diurnals 
P.35 

NON-INTEGRATED REFUELING SYSTEMS 

* EVAPORATIVE TEST 

FTP 

IS min. MAX 

DRAIN FUEL TANK. 

40% FUELING. 

DIURNAL HEAT BUILD. 

(71-96 T) 

(MEASURE EMISSIONS) 

0 • 18 Hours 

DRAIN FUEL TAN K.. 

40% FUELING. 

DIURNAL HEAT 31'ILD. 

(71-96T) 

(MEASUREEMISSIONS) 
P.36 

Table 2 

Canister Volumes Required to Comply 

with Various Test Procedures for Evap-Only Systems 

Canister Sized) 

Charcoal Type: Ford Nissan 

Purge Rate: Low Low 

Test Sequence 

FTP 1.8 3.0 

FTP+1 representative diurnal 2.5 .4.2 

FTP+2 representative diurnals 4.5 9.6 

Notes: 

1) FTP = LA-4+DiurnaI+3-Bag Test+Hot Soak 

3 

2) Purge rate = 8.0 ft /LA-4 for all cases 

3) Fuel tank size = 17.6 gallons 

4) Fuel vapor pressure = 9.0 Lbs. RVP 

o 

5) Representative diurnal temperature range = 71-96 F. 
P.37 

0 

0 

Evap-Only Systems 

If onboard refueling controls were not promulgated and 

Class C commercial gasoline vapor pressure was reduced to 

9.0 Lbs. RVP:: 

Retain test procedure revisions discussed for 

non-integrated systems 

If onboard refueling controls were not promulgated and 

Class C commercial gasoline RVP was reduced to some level 

higher than 9.0 (i.e., 10.5 RVP as in the API/MVMA joint 

industry recommendation): 

Raise certification fuel RVP to the commercial fuel 

level 

Serious consideration would be given to simulating 

in-use fuel tank heating in the test procedure 

Two reasons for more representative fuel tank temperature 

simulation 

Fuel boiling in-use, which cannot be simulated by 

multiple diurnals 

Encouragerer: of fuel cooling techniques 
P.38 

Evaporative Emissions Modelling 

Model Description: 

• An accounting model of evaporative emissions systems that includes the following 

key vehicle components: 

Fuel tank (vapor source) 

Charcoal canister (vapor storage) 

Purge control system (vapor sink) 

• The model maintains a continuous canister history during and between evaporative 

emissions events (drives, hotsoaks, diurnals). 

• Explicit accounting for interactions between driving pattern, purge control, fuel tank 

vapor generation, and charcoal adsorption characteristics. 
P.39 

Evaporative Emissions Modelling 

Vapor Source Modelling 

• All vapors assu&ed are to originate from the fuel tank in response to changes in 

temperature of liquid fuel in the tank. 

• Vapor generation is precalculated based on the application of rigorous non-ideal 

vapor-liquid equilibrium relationships to pure-component descriptions of fuels. 

• Temperature rises used to simulate various driving events: 

Event Temp. Rise HCMass Description 

Diurnal 

Hot Soak 

Drive 

60-84 OF 25.0 g FTP diurnal 

71-96 °F 40.0 g In-use diurnal 

FTP hotsoak 

In-use hotsoak 

-15.0 °F 18.1 g In-use drives starting at 71 °F 

39.5 g FTP drives 

75.1 g In-use drives starting at 96 °F 

.5-1.0 above 6.0 g 

EOD temp. 25.0 g 

Vapor generation during vehicle operation (running losses): 

- Fuel tank temperature profile obtained from on-road vehicle testing. 

- Hydrocarbon mass and vapor volume are calculated as a function of time. 
Evaporative Emissions Modelling 

Canister Modelling: 

» Canister purge characteristics obtained from laboratory load/purge studies. 

• Non-linear nature of adsorption of hydrocarbons on activated charcoal is 

accounted for. 

• All hydrocarbon vapors entering the canister are assumed to be adsorbed up 

to canister breakthrough. 

• Quantity of hydrocarbons purged from the canister is a function of purge air 

volume and current canister loading. 
P.41 

Evaporative Emissions Modelling 

Purge Control Modelling 

• Purge rate proportional to instantaneous fuel consumption (horsepower). 

• Fuel consumption (horsepower) determined from instantaneous vehicle speed and 

acceleration. 

• Purge rate set to zero during certain driving modes, such as low-speed driving 

and deceleration. 
P.42 

Evaporative Emissions Modelling 

Model assumptions: 

• Fuel tank capacity is 17.6 gallons, and tank is 40% full. 

• 90.0 g refueling capacity is needed. 

Model Inputs: 

• Driving schedule (e.g., LA-4). 

• Fuel tank vapor generation table for running losses. 

• Canister purge characteristics. 

• Canister size and initial loading. 

• Maximum purge rate, (determines total purge volume over the selected driving schedule.) 

• Mass of hydrocarbons generated during diurnal and hotsoak. (Incorporates the effects 

of fuel vapor pressure and ambient temperature.) 

Model Limitations: 

• Fuel tank pressure not modelled. 

• Fuel tank temperature history not maintained. Back-to-back drives modelled as being 

equivalent to drives widely separated in time. 
P.43 

June 1988 

Current Running Loss Program 

0 Sample 

8 to 10 automobiles 

1983 and newer model years 

Both carbureted and fuel injected 

0 Test Procedures 

3LA4s - back to back 

AlI tests with a diurnal prior to LA4s 

Small subset of tests both with and without diurnal . 

0 Diurnal Temperatures - 75 to 95°* rise, 60 to 80° rise 

0 Cell Temperatures - 95°, 80° 

Fuels-11.7, 10.4, 9.0, 7.0* psi RVP 

Fuel Tank Temperature Rise 

Original target - 15° rise after 3 bags 

Current target - 15° rise after 3 bags, 22° after 6 bags 

Standardize Canister Weight Before Each Prep 

Using 11.7 RVP fuel and 80°F, base is the weight following 

the LA4, 1 hr. soak, LA4, 1 hr soak 

0 

0 

* The 7.0 RVP fuel test has only one set of temperatures 

which are 95° cell temperature and 75° to 99° diurnal 
Results - Graphics Follow 

Average of first five vehicles 

Results reflect the tests with a diurnal 

Significant running losses dependent on 

Fuel RVP 

Cell temperature 

Length of cycle 

Further study required -- parameters of interest on last 

page 
^ r\ 

10 -

8 -

i eo 

* .4-

2 -

t 

o -

Running Losses 

FTP Cycle 

am 

mam 1 ^ H 1 H H 

7 9 10.4 

Fuel RVP 

11.7 

- in 

IU 

- 8 

• 6 

- 4 

- 2 

- 0 

'i 

U 80°F 

B 95°F 
Running Loss Parameters 

Fuel Tank Temperature 

Fuel Volatility 

Ambient Temperature 

Vehicle Technology 

Driving Cycle 

Length 

Acceleration/Speed 

Driving Pattern History 
Running Losses 

3 LA4 Cycles 

E 

^ > 

O 

X 

10 

10.4 

Fuel RVP 

11.7 

8 

- 6 

TJ