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.

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.