OAR Box 1850 

Prepped by Ollie Stewart 

Document Number: 

74) IV-B-4 

Docket Number: 

A-90-07 

p.i 

Printed 11/18/2008 11:09:28 AM Sheet 74 of 161 
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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

ANN ARBOR. MICHIGAN 48105 

MAY 2 5 1994 

MEMORANDUM 

SUBJECT: Summary of Fuel Tank Temperature Data 

OFFICE OF 

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MAY 2 6 BW U 

EPA AIR DOCKET 

FROM: 

THRU: 

TO: 

Robert Johnson, Environmental Protection Specialist / 7/, . , 

Special Regulatory Projects Branch .~ (j 

Judith Gray, Senior Project ManagerCJ^&_^V_^Ot~ _£, 

Special Regulatory Projects Branch / / ) 

Air Docket A-90-07 

In order to determine a representative temperature range for 

generating evaporative emissions for emissions speciation and 

biological testing of fuels and fuel additives (F/FA) •, EPA 

consulted data which had been gathered for the recent evaporative 

emissions rulemaking (58 FR 16002, March 24, 1993). These data 

show, among other parameters, increases in fuel tank temperatures 

that may be expected to occur during in-use vehicle operation. In 

normal vehicle operation, the temperature of the fuel in the 

vehicle fuel tank increases, because of heat generated internally 

in pumping the fuel from the tank to the engine and back again (a 

portion of this fuel is not used by the engine and is returned to 

the fuel tank via a return line), and because of heat from sources 

external to the fuel system, e.g., engine heat or proximity of fuel 

lines to the exhaust system. 

To obtain these data, an EPA contractor conducted a series of 

139 fuel tank temperature tests on in-use light-duty vehicles (LDV) 

and 30 tests on in-use light-duty trucks (LDT). The purpose of 

this testing was to develop LDV/LDT vehicle fuel tank temperature 

profiles resulting from normal vehicle operation. Three separate 

test sequences were conducted from September, 1989 to September, 

1991, at two test tracks located at warm-weather sites. Vehicles 

were selected to represent high sales volume vehicle/engine 

combinations from model years 1983 to 1992. The hot-soak/running 

loss-related portions of the test sequences consisted of measuring 

vehicle fuel tank temperatures at selected intervals while the 

vehicles were operated over a series of EPA urban driving cycles. 

The results of these test sequences are summarized in Table 1, and 

the portions of the data generated during the first and second test 

sequences are attached. Data gathered during third test sequence 

may be found in EPA Public Docket A-89-18 (Item number IV-D-4). 

All of the temperature gain data in Table 1 below are weighted 

averages of the tabulated data. 
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Table 1 

Test Sequence 

September 1989 

August 1990 

August 1991 

Total/Average 

Number of Tests 

59 

43 

94 

196 

Avg Temp. Gain 

27°F 

32°F 

31°F 

30°F 

In arriving at a representative temperature to be maintained 

by the evaporative emissions generator used by F/FA producers for 

generating evaporative emissions for F/FA testing purposes, EPA 

judged it appropriate to add the average in-use temperature gain 

of 30°F from Table 1 to an initial temperature of 100°F. This 

initial temperature is roughly comparable to the upper end of the 

initial fuel temperature range specified in the evaporative rule 

for running loss/hot soak testing (i.e., 98°F), rounded to the 

nearest 5°F. To be conservative, the high end of the temperature 

range was chosen in order to help assure that ample quantities of 

emissions are generated for testing purposes. 

Attachments