ISO 5175-2:2017 specifies the general requirements and tests for safety devices for fuel gases and oxygen or compressed air which do not incorporate a flame (flashback) arrestor used downstream of manifold, cylinder and/or pipeline outlet regulators, and upstream of blowpipes for welding, cutting and allied processes.
ISO 5175-2:2017 does not specify the location of these devices in the gas system.
ISO 5175-2:2017 in not applicable to safety devices which incorporate a flame arrestor, covered by ISO 5175-1.