Flashback arrestors are designed to prevent reverse oxygen and propane flow and flashback by utilizing an internal reverse flow check valve and a flame arrestor that quenches the flashback flame. Flashback arrestors also help protect hoses, regulators, and cylinders. Flashback arrestors are necessary for all premix torches since they are prone to flashback and are recommended when multiple torches are connected on the same fuel and oxygen supply system.
Flashback arrestors come with a standard "B" fitting and are directional (meaning that the flow of gas only goes one way). Flashback arrestors cannot be used with gas pressures under 5 to 7 lbs of pressure because the mechanism needs this minimum pressure to open and allow gas to flow.
If an oxygen concentrator is used, a flashback arrestor will be needed on the fuel source and not the oxygen concentrator. Using a flashback arrestor on an oxygen concentrator will severely limit the oxygen output.