Flashback Arrestor in Gas Welding

The last thing one wants is a fire going on inside the cylinders!

The purpose of the fire arrestors is to provide a point where a flame travelling backwards inside the hose is stopped before it gets to the cylinders. A non-return valve cannot do that.

The flame can travel backwards, only if mixture of oxygen and fuel is made.

If non-return valve functions ok, then mixtrure can not be made, so flame can not travel back. Am I wrong?

Non-return valves cannot be relied on to snuff-out a flame. Purpose-designed flame arrestors can.

Any valve that operates as a check valve system can in fact work very well to prevent flashbacks from occurring. But, if for some reason you were to introduce an explosive mixture such a acetylene to a higher PSI then it cn handle (such as 40-60 PSI oxygen) it can in fact explode and cause fire in hose, etc. It takes little to make a very usable set of tools such as O/A torches one heck of a bad tool. Use the flask back arrestors and stop worrying why or how they work.

While using Oxy-acetylene cutting torch, you might have heard of " back fire" due to insertion of spark or spatter through nozzle holes of cutting torch while working in encloser or making holes in thick sections or cutting of thick sections from where molten metal is not flowing properly, that type of fire can travel through hoses and history knows it well. NRVs can stop the reverse flow but can not cut of fire.