cutting off an o/a torch

[kdc3]

I can never remember which one you are technically supposed to cut off first, and why. My torch has back blast arrestors and I've always trusted that they will keep me safe so I think? can't remember without doing it? but I think I cut off the acetylene first.

[Clay Walters]

Yep. Flame goes out. The other way it doesn't.
:)

[FearcityINC]

My teacher says to try to do em at the same time.....easier said than done though. I try to at least do fuel, then o2 in a somewhat fluid motion.

[seamus]

I was taught to turn off fuel first. The o2 will blow the flame out.

[yotawheeler]

A before O or up you go....was what i was told when i learned to use the cutting torch...thats about all the teacher told me before buggering off lol

[runchman]

I googled a little bit and found some say turn oxygen off first, then acetylene. I've always done it that way and it seems to make sense to me - you transition from a normal flame to just a sooty acetylene flame, just like when you lit it with just the acetylene open.

But then others say turn off the acetylene first.

I'm guessing this conflicting info means it probably isn't a life-or-death issue :)

- John

[GWallace]

By turning off the Acetylene first you eliminate the sooty flame & it cuts off the fuel supply as O2 will not burn. (Yep I said O2 doesn't burn) it supports combustion but is not the fuel..... I know it's semantics and of you add O2 to anything with an ignition source you can expect a fire, but chemically speaking O2 doesn't burn.

[GWallace]

I've always done it that way and it seems to make sense to me - you transition from a normal flame to just a sooty acetylene flame, just like when you lit it with just the acetylene open.

Except that you trying to extinguish it not light it.

[runchman]

Except that you trying to extinguish it not light it.

Well, my philosophy was that you don't want oxygen on w/o acetylene, based on the lighting sequence.

BUT, I poked around on the web some more and you can find reference material that says to shut down each way.

So choose your poision, some soot, or maybe an o2-rich 'pop'.

[GWallace]

The reality is that O2 is already in the air....acetylene is not. If you are trying to extinguish the flame you remove the fuel. Not trying to argue just giving my opinion. I agree, choose your poison. My choice is to remove the fuel.

[MJDamiani]

I took an OA safety course a few years ago. The STANDARD shut off procedure was Ox first then the Gas. The EMERGENCY shut down procedure was gas off first. The course was done at a vocational school with the representatives of the torch manufacturer and of coarse the usual VHS film about torch safety. Both will work, just adding my 2cents.

[littlefuzz]

I alway shut off acetylene first, who wants all that soot floating around? Same reason why I open fuel and oxygen before lighting the torch.

[Clanweld]

What I'd ask is does it matter? I turn off the gas first for covenience; no soot like the man said. If there was a safety reason for a particular order I'd like to know it, otherwise off is off. :<>