The agenda includes continuation of supply line discussions, corrections to UN R134/03, clarifications needed in UN R134/03 with responses from test labs, next steps, and scheduling of next meetings.

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.

The task force completed working documents for transposition of the optional part of GTR 13 on liquefied hydrogen (GRSP/2025/41, GRSP-78-15/Rev.1, GRSP-78-16/Rev.2), updating ISO 17268-1:2025 references for receptacle geometry, and incorporating ISO 19887-1:2024 and periodic inspection requirements into UN Regulation No. 134 (WP.29/2026/56, WP.29/2026/136, WP.29/2026/57). The task force recommended deferring discussions on supply line standards to IWG GTR 13 Phase 3 and provided recommendations for hydrogen storage and fuel system requirements.

Proposal to amend para. 2.1. to specify that appropriate adaptors are test components designated by the CHSS manufacturer substituting for the container valve, additional TPRD, and end plug, modify paras. 5.1.1., 5.1.2., 5.2., 9.2.1., and 9.2.3.2. to clarify that connections between supply lines for additional TPRDs and appropriate adaptors shall meet test requirements and are within the scope of the test, amend para. 9.2.1. to delete references to hydraulic mating connections, and modify Annex 3 para. 5.1. to include supply lines for additional TPRDs in the CHSS test article.

Proposal to amend the definition of ‘appropriate adaptor’ to specify that it is a test component specified by the manufacturer that substitutes for the container valve, additional TPRD, and/or end plug, modify para. 5.1.1. to require that three containers as well as supply lines for additional TPRDs through appropriate adaptors be hydraulically pressurized until burst, modify para. 5.1.2. to require that three containers as well as supply lines for additional TPRDs through appropriate adaptors be hydraulically pressure cycled without rupture for 22,000 cycles, and modify para. 5.2. to require that one container equipped with container attachments and supply lines for additional TPRDs through appropriate adaptors be tested, with connections between supply line and adaptor meeting requirements and worst-case approach applicable at discretion of Technical Service and Type Approval Authority.

Proposal to amend para. 2.1. to specify that an appropriate adaptor means a test component specified by the CHSS manufacturer that substitutes for the container valve, additional TPRD, and end plug, and includes an outlet with the proper fitting size and geometry to connect the supply line to the additional TPRD if applicable, with a note defining container valve and end plug, amend para. 5.1.1. to require that connections between the supply line for additional TPRDs and appropriate adaptor(s) shall meet the requirements and are within the scope of the test, amend para. 5.1.2. to require that connections between the supply line for additional TPRDs and appropriate adaptor(s) shall meet the requirements and are within the scope of the test, amend para. 5.2. to require that connections between the supply line for additional TPRDs and appropriate adaptor(s) shall meet the requirements and are within the scope of the test, and amend Annex 3 para. 5.1. to delete “through appropriate adaptors” from the requirement regarding supply lines for additional TPRDs.