This Part of this International Standard specifies the general requirements and tests for safety devices for fuel gases and oxygen or compressed air incorporating a flame (flashback) arrestor used downstream of manifold, cylinder and (or) pipeline outlet regulators, and upstream of blowpipes for welding, cutting and allied processes. This standard does not specify the location of these devices in the gas system. This standard does not include requirements for safety devices which do not incorporate a flame arrestor which are covered by ISO 5175 2 . This standard does not cover the use of safety devices incorporating flame arrestors for applications with premixed oxy/fuel or air/fuel gas supply systems, for example downstream of gas mixers or a generator to produce hydrogen/oxygen mixture by electrolytic decomposition of water.