Durability testing.
Durability testing. You normally need to perform a separate durability demonstration for each substantially 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/m 2 (0.40 W-hr/m 2/min) on the tank surface for at least 450 hours. 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 § 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° to −15° from level. This test must be performed at a temperature of 28 °C ±5 °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:
(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/m
2 (0.40 W-hr/m
2/min) on the tank surface for at least 450 hours. 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 § 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° to −15° from level. This test must be performed at a temperature of 28 °C ±5 °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: