P.1 

OAR Box 1147 

Prepped by Ollie Stewart 

Document Number: 

184) IV-E-57 

Docket Number: 

A-87-11 

Printed 4/22/2008 2:42:57 PM Sheet 184 of 242 
P.2 

' fl t» 

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.3 

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 

performance as integrated systems 

Revised evap-only procedures if onboard controls are 

not promulgated 
P.4 

Test Procedures for 

Integrated Refueling Control Systems 
P.5 

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 
REFUELINQ TEST PROCEDURE 

(AUGUST 19, 1987) 

Drain R» l Tank 

8MkV«Mete fort Hours 

R M I In SHED te BiMMtmugh 

Integrated Systam 

cgnlatcr Pvrq». Cyclic PrtYt 

a. Disconnect Vapor Una lo Canlalar 

b. Drain Fuel Tank 

c. 40% Fueling 

d. Reconnect Vapor Una to Canister 

a. Drive Ona LA-4 

I. Ona Hour Hot Soak 

g. Repeat (a) and (f) Twlca 

h. Disconnect Vapor Una to Canister 

I. Drain Fual Tank 

j. 40% Fueling 

k. Reconnect Vapor Una to Canister 

L Heat Build ( W • Tf Initial, 

24'«1'FRIse) 

m. Rapaal (a) Through (0 Twice 

n. Drive Ona LA-4 

v. wl?-1 

Integrated System 

Canister Puroe. Continuous Drive 

a. Disconnect Vapor Una to Canlalar 

b. Drain Fuel Tank 

&40%Fuaing 

d Reconnect Vapor Una to Caniater 

a. Drive Repeated LA-4a Untk Mleage 

Accumulated • IHeags Raqulrad for 

Purge Equtvalanl to Cycle Drive. 

Mileage Accumulation 8topa al tha 

First Idle Past the Mleage 

Requirement 

1 

Non-Integrated System 

Canister Puma. Continuous Drive 

a. Disconnect Vapor Una lo Caniater 

b. Drain Fuel Tank 

e. M % FueHng 

d. Reconnect Vapor Una to Caniater 

a. Drive Repeated LA-4a Until 

• 5% of Tank Volume Is Consumed 

YtWritffwIPnii 

• Dlsoonnact Una to Canister 

• Drain Fuel Tank 

• 10% Fusing 

• Soak Vat** * to 24 Hours 

I 

Refusing Fmhitnna Measurement 

Reconnect Vapor Una to Caniater 

Fual to Automate Noa * 9hut-otf (M % Mnlmum Fueling) 

Restart Fueling Folowlng Any Prematura 8hi*offs 

Within 15 Seconds 

b> 
EVAPORATIVE ANO TAILPIPE PROCEDURE (FTP) 

(AUGUST 19, 1987) 

P.7 

f Start J 

| Drain Fuel Tank j 

| Vehicle Temperature Stabilization (as required)! 

| Load Canisters To Breakthrough | 

DISCONNECT REFUELING CANISTER 

CONNECT REFUEUNQ CANISTER 

| Fuel Drain & Fill | 

i 

DISCONNECT REFUELING CANISTER 

| Dyno Preconditioning j 

—I Cold Soak Parking I ** 

iDies-sil 

l^jnjyj 

CONNECT REFUEUNG CANISTER • 

Fueling 

* Drain 

* 40% Fill 

T 

Diurnal Heat Build 

* Heat Fuel - 1 Hour 

• 60 - 84 ' F 

Evap. Test 

Not Req. 

I 

Diumal 

Enclosure 

Test 

Cold Start Exhaust Test > 

Evap. Test 

Not 

Performed 

HC Running 

Losses as Required 

i r 

£ ) Hot Start Exhaust TesTj 

Hot Soak 

Enclosure 

Test 

©" T 

I 

1 

I 

1 hour MAX 

•5 min. MAX 

0-1 hr 

12-36 hrs 

(no MAX 

for diesels) 

I 

ETH 

10 min. 

' 7 min. MAX 
P.8 

Simplified Integrated Test Procedure 

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 

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) 

Provides substantial, but not complete control of evap 

emissions on high-ozone days 
P.9 

REFUELING TEST PROCEDURE: 

INTEGRATED SYSTEMS 

FTP 

I 

EPA URBAN 

DYNAMOMETER 

DRIVING SCHEDULE 

I 15 min. MAX 

DISCONNECT REFUELING 

CANISTER 

I 

I S min. MAX 

REMOVE FUEL FILLER CAP. 

DRAIN FUEL TANK. 

I 8 to 24 Hours 

VEHICLE TEMPERATURE STABILIZATION 

I 

10% FUELING (81-*4*F FUEL) 

I 

CONNECT REFUEUNG CANISTER 

I 

PLACE VEHICLE IN SHED 

I 

3 Hours MAX 

MEASURE REFUELING 

EMISSIONS 
P.10 

Table 1 

Canister Volumes Required to Comply 

with Various Test Procedures 

Integrated Onboard Systems 

Charcoal Type: 

Purge Rate: 

Test Sequence 

NPRM 

FTP+Ref 

FTP+LA-4+Ref 

FTPCHigh Temp DiurnaD+Ref 

FTP/Di/Ref 

Ford 

H|Sh 

4.4 

4.2 

4.1 

4.2 

5.5 

Canister S 

Low 

5.3 

5.1 

5.1 

5.2 

6.6 

ize(l) 

Nissan 

High Low 

4.4 9.4 

4.8 18.5 

4.1 9.7 

4.9 »2 0 

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 = 1.7.6 gallons 

4) Design refueling capacity = 90.0 g (85% fill) 
P.11 

0 

0 

Modifications 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.12 

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 

o 

P.13 
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 
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 

uninterupted diurnals 
P.16 

NON-INTEGRATED REFUELING SYSTEMS 

Z EVAPORATIVE TEST 

FTP 

15 min. MAX 

DRAIN FUEL TANK. 

40% FUELING. 

DIURNAL HEAT BUILD. 

(71-96 T) 

(MEASURE EMISSIONS) 

0 -18 Hours 

DRAIN FUEL TANK. 

40% FUELING. 

DIURNAL HEAT BUILD. 

(71-96*F) 

(MEASURE EMISSIONS) 
P.17 

Table 2 

Canister Volumes Required to Comply 

with Various Test Procedures for Evap-Only Systems 

Canister S 

Charcoal Type: Ford 

Purge Rate: Low 

Test Sequence 

FTP 1.8 

FTP+1 representative diurnal 2.5 

FTP+2 representative diurnals 4.5 

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 

5) Representative diurnal temperature range 

zed ) 

Nissan 

Low 

3.0 

4.2 

9.6 

= 71-96 °F. 
P.18 

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 

Encouragement of fuel cooling techniques 
P.19 

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.20 

Evaporative Emissions Modelling 

Vapor Source Modelling 

All vapors assumed 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 

Diurnal 

Hot Soak 

Drive 

Temp. Rise 

60-84 OF 

71-96 °F 

.5-1.0 above 

EOD temp. 

-15.0 °F 

HC Mass 

25.0 g 

40.0 g 

6.0 g 

25.0 g 

18.1 g 

39.5 g 

75.1 g 

Description 

FTP diurnal 

In-use diurnal 

FTP hotsoak 

In-use hotsoak 

In-use drives starting at 71 °F 

FTP drives 

In-use drives starting at 96 °F 

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. 
P.21 

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.22 

Evaporative Emissions Modelling 

Purge Control Modelling 

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

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

accelleration. 

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

and decelleration. 
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.24 

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 td back 

All tests with a diurnal prior to LA4s 

Small subset of tests both with and without diurnal 

0 

0 

0 

0 

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

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 

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

which are 95° cell temperature and 75° to 99° diurnal 
P.25 

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 
Running Losses 

FTP Cycle 

E 

o 

X 

10 

9 10.4 

Fuel RVP 

11.7 

- 8 

- 6 

- 4 

- 2 

- 0 
(0 

<D 

(0 C) 

o o 

-I > 

c < 

c -J 

3

 CO 

DC " 

d 

o> 

Q. 

> 

CC 

T i i " 

co 

- | 1 1 1 r T " 

<M 

Qui/6) OH 
Running Loss Parameters 

Fuel Tank Temperature 

Fuel Volatility 

Ambient Temperature 

Vehicle Technology 

Driving Cycle 

Length 

Acceleration/Speed 

Driving Pattern History