Proposal to amend Annex 3 paragraph 5.1 regarding the CHSS test article. The modification adds supply lines for additional TPRDs through appropriate adaptors to the required test article components, and clarifies that vent lines shall be connected to TPRDs to direct TPRD exhausts in a manner representative of the configuration in the vehicle. The task force identified contradicting language in the regulation regarding supply lines for additional TPRDs and aims to correct this inconsistency.

Test agencies expressed concern about knowing the material and fitting configuration of adapters in advance of testing. One agency suggested adapter material should match the original valve material strength. Agencies agreed small diameter supply lines present no pressure and temperature issues but suggested mandating a one to two second hold at maximum pressure during cycles. Test agencies questioned whether adapters and TPRD plugs are considered part of the test and whether leakage constitutes failure. Components not covered by UN R134 should be tested per ISO 19887-1.

Proposal to amend Annex 3 para. 5.1. to specify that the CHSS test article shall include the container and primary closure devices such as shut-off valve(s), check valve(s), and TPRD required to isolate the system, container attachments including gas housings or barriers that could impede TPRD response, as well as supply lines for additional TPRDs through appropriate adaptors, and vent lines shall be connected to TPRDs to direct TPRD exhausts in a manner representative of the configuration in the vehicle.

Test agencies raised concerns about hydrogen fuel safety testing. Agencies were concerned they might not know adapter material and fitting configuration in advance of performing the test. One agency suggested adapter material should at least be the same strength as original valve material. Another agency expressed concern that adapter materials could be affected by hydraulic fluid. Most test agencies agreed there are likely no issues with pressure and temperature development of test fluid from small diameter supply lines. One agency stated flow restriction would create high temperatures that would undermine the cold cycling test. Another agency suggested pressure drop in supply line(s) can be accommodated by mandating a 1 to 2 second hold at maximum pressure during a cycle.