[Code of Federal Regulations]
[Title 40, Volume 30]
[Revised as of July 1, 2004]
From the U.S. Government Printing Office via GPO Access
[CITE: 40CFR1051.515]

[Page 629-632]
 
                   TITLE 40--PROTECTION OF ENVIRONMENT
 
         CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)
 
PART 1051_CONTROL OF EMISSIONS FROM RECREATIONAL ENGINES AND VEHICLES
--Table of Contents
 
                        Subpart F_Test Procedures
 
Sec. 1051.515  How do I test my fuel tank for permeation emissions?

    Measure permeation emissions by weighing a sealed fuel tank before 
and after a temperature-controlled soak.
    (a) Preconditioning fuel soak. To precondition your fuel tank, 
follow these five steps:
    (1) Fill the tank with the fuel specified in Sec. 
1051.501(d)(2)(i), seal it, and allow it to soak at 28 5 [deg]C for 20 weeks. Alternatively, the tank may be 
soaked for a shorter period of time at a higher temperature if you can 
show that the hydrocarbon permeation rate has stabilized.
    (2) Determine the fuel tank's internal surface area in square-meters 
accurate to at least three significant figures. You may use less 
accurate estimates of the surface area if you make sure not to 
overestimate the surface area.
    (3) Fill the fuel tank with the test fuel specified in Sec. 
1051.501(d)(2)(ii) to its nominal capacity. If you fill the tank inside 
the temperature-controlled room or enclosure, do not spill any fuel.
    (4) Allow the tank and its contents to equilibrate to 282 [deg]C.
    (5) Seal the fuel tank using nonpermeable fittings, such as metal or 
TeflonTM.
    (b) Permeation test run. To run the test, follow these nine steps 
for a tank that was preconditioned as specified in paragraph (a) of this 
section:
    (1) Weigh the sealed fuel tank and record the weight to the nearest 
0.1 grams. (You may use less precise weights as long as the difference 
in mass from the start of the test to the end of the test has at least 
three significant figures.)
    (2) Carefully place the tank within a ventilated temperature-
controlled room or enclosure. Do not spill any fuel.
    (3) Close the room or enclosure and record the time.
    (4) Ensure that the measured temperature in the room or enclosure is 
282 [deg]C.
    (5) Leave the tank in the room or enclosure for 2 to 4 weeks, 
consistent with good engineering judgment (based on the permeation 
rate). Do not stop soaking before 4 weeks unless you know that you can 
measure the weight loss during the test to at least three significant 
figures earlier.
    (6) Hold the temperature of the room or enclosure to 282 [deg]C; measure and record the temperature at least 
daily.
    (7) At the end of the soak period, weigh the sealed fuel tank and 
record the weight to the nearest 0.1 grams. (You may use less precise 
weights as long as the difference in mass from the start of the test to 
the end of the test has at least three significant figures.)
    (8) Subtract the weight of the tank at the end of the test from the 
weight of the tank at the beginning of the test; divide the difference 
by the internal surface area of the fuel tank. Divide this g/
m2 value by the number of test days (using at least three 
significant figures) to calculate the g/m2/day emission rate. 
Example: If a tank with an internal surface area of 0.72 m2 
weighed 31882.3 grams at the beginning of the test and weighed 31760.2 
grams after soaking for 25.03 days, then the g/m\2\/day emission rate 
would be: (31882.3 g-31760.2 g) / 0.72 m2 / 25.03 days = 6.78 
g/m2/day.
    (9) Round your result to the same number of decimal places as the 
emission standard.
    (c) Determination of final test result. To determine the final test 
result, apply a deterioration factor to the measured emission level. The 
deterioration factor is the difference between permeation emissions 
measured before and after the durability testing described in paragraph 
(d) of this section. Adjust the baseline test results for each tested 
fuel tank by adding the deterioration factor to the measured emissions. 
The deterioration factor determination must be based on good engineering 
judgement. Therefore, during the durability testing, the test tank may 
not exceed the fuel tank permeation standard described in Sec. 1051.110 
(this is known as ``line-crossing''). If the deterioration factor is 
less than zero, use zero.
    (d) Durability testing. You normally need to perform a separate 
durability demonstration for each substantially

[[Page 630]]

different combination of treatment approaches and tank materials. 
Perform these demonstrations before an emission test by taking the 
following steps, unless you can use good engineering judgment to apply 
the results of previous durability testing with a different fuel system. 
You may ask to exclude any of the following durability tests if you can 
clearly demonstrate that it does not affect the emissions from your fuel 
tank.
    (1) Pressure cycling. Perform a pressure test by sealing the tank 
and cycling it between +2.0 psig and -0.5 psig and back to +2.0 psig for 
10,000 cycles at a rate 60 seconds per cycle.
    (2) UV exposure. Perform a sunlight-exposure test by exposing the 
tank to an ultraviolet light of at least 24 W/m2 (0.40 W-hr/
m2/min) on the tank surface for 15 hours per day for 30 days. 
Alternatively, the fuel tank may be exposed to direct natural sunlight 
for an equivalent period of time, as long as you ensure that the tank is 
exposed to at least 450 daylight hours.
    (3) Slosh testing. Perform a slosh test by filling the tank to 40 
percent of its capacity with the fuel specified in Sec. 
1051.501(d)(2)(i) and rocking it at a rate of 15 cycles per minute until 
you reach one million total cycles. Use an angle deviation of +15[deg] 
to -15[deg] from level. This test must be performed at a temperature of 
28 [deg]C 5 [deg]C.
    (4) Final test result. Following the durability testing, the fuel 
tank must be soaked (as described in paragraph (a) of this section) to 
ensure that the permeation rate is stable. The period of slosh testing 
and the period of ultraviolet testing (if performed with fuel in the 
tank consistent with paragraph (a)(1) of this section) may be considered 
to be part of this soak, provided that the soak begins immediately after 
the slosh testing. To determine the final permeation rate, drain and 
refill the tank with fresh fuel, and repeat the permeation test run (as 
described in paragraph (b) of this section) immediately after this soak 
period. The same test fuel must be used for this permeation test run as 
for the permeation test run performed prior to the durability testing.
    (e) Flow chart. The following figure presents a flow chart for the 
permeation testing described in this section, showing the full test 
procedure with durability testing, as well as the simplified test 
procedure with an applied deterioration factor:


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[GRAPHIC] [TIFF OMITTED] TR15JA04.002


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[67 FR 68347, Nov. 8, 2002, as amended at 69 FR 2442, Jan. 15, 2004]