The requirements of CGA E-6 cover pipeline protective devices (Pf) for use in fuel gas pipelines supplying equipment using oxygen or air downstream. Examples of such equipment are torches or burners that internally premix the oxygen (or air) and fuel gas as outlined in NFPA 51, Design and Installation of Oxygen-Fuel Gas Systems for Welding, Cutting, and Allied Processes.
This standard does not cover devices used in a system where a combustible mixture of fuel gas and oxygen or fuel gas and air is passed through the Pf device.
