ISO 21755-2:2020 pdf download – Motorcycles – Measurement method for evaporative emissions
4.6.1 A separate durability demonstration for each substantially different combination of treatment approaches and fuel tank materials shall be performed by taking the following steps.
4.6.1.1 Pressure cycling
A pressure test shall be conducted by sealing the tank and cycling it between 115,1 kPa absolute pressure and 97,9 kPa absolute pressure and back to 115,1 kPa absolute pressure for 10 000 cycles at a rate of 60 s per cycle.
4.6.1.2 UV exposure
A sunlight exposure test shall be conducted by exposing the fuel tank to an ultraviolet light of at least 24 W/m 2 (0,40 (W·h/m 2 )/min) on the tank surface for at least 450 h. Alternatively, the non-metallic fuel tank may be exposed to direct natural sunlight for an equivalent period of time, as long as it is ensured that it is exposed to at least 450 daylight hours.
4.6.1.3 Slosh testing
A slosh test shall be conducted by filling the non-metallic fuel tank to 40 % of its capacity with the reference fuel set out in 4.2 or with a commercial premium-grade fuel at the choice of the manufacturer. The fuel tank assembly shall be rocked at a rate of 15 cycles per minute until 1 000 000 total cycles are reached. An angle deviation of +15° to –15° from level shall be used and the slosh test shall be conducted at an ambient temperature of 301,2 K ± 5,0 K.
4.6.2 Final fuel tank durability test results
Following the durability testing, the fuel tank shall be soaked according to the requirements specified in 4.3 to ensure that the permeation rate is stable. The period of slosh testing and the period of ultraviolet testing 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, the fuel tank shall be drained and refilled with fresh reference fuel set out in 4.2. The permeation test run laid down in 4.4 shall be repeated immediately after this soak period. The same test fuel requirement shall be used for this permeation test run as for the permeation test run conducted prior to the durability testing. The final test results shall be calculated in accordance with 4.5.
4.6.3 The length of ‘soak’ during durability testing may be included in the fuel soak period provided that fuel remains in the tank. Soak periods may be shortened to 10 weeks if performed at 316,2 K ± 5,0 K.
4.7 Fuel line assembly test requirements
4.7.1 Fuel line assembly permeation physical testing procedure The manufacturer shall conduct a fuel line assembly test, including the fuel hose clamps and the material to which the fuel lines are connected on both sides, by performing a physical test in accordance with the requirements in 4.6.2 to 4.6.3. The piping material to which the fuel lines are connected at both sides of the fuel line shall be plugged with impermeable material. The fuel hose clamps shall be tightened with the torque specified for series production.