fixing popping in scrounged O/A cutting torch?

Grant: My old Meco heads were popping and I replaced the "O" rings. Problem solved. Any chance these have an O ring?

-Mike

They do, down below where the torch head attaches to the body. I'll look at that area as well, thanks.

Grant

Grant you can just buy the replacement o-rings from Harrold at Hansen and Miller.

Is this while welding or just with the torch lit by itself? I too often get bangs from my torch while welding, but always assumed it was just my poor technique overheating the weld and causing sparks that enter the torch.

Just trying to narrow down the symptoms.

Nothing to do with welding, this is with the cutting attachment installed, and just in free air, not in use at all.

GWE

"xray" wrote: (clip) I too often get bangs from my torch while welding, but always assumed it was just my poor technique (clip) ^^^^^^^^^^^^^^^^ Based on Grant's response, my reply is a little off-topic, but I will mention anyway: if your torch is in good shape (O-rings OK, etc) then popping while you are welding probably means you are running too small a flame for the tip size, allowing the flame to travel back through the opening.

On mine it was bad "O" rings.

There are some causes to popping. If everything is well sealed.

• to low gas speed. If the gas is coming out to slow, the flame can burn back (into the tip), get a lot of volume to burn and thus explode.

• to much heat. Acetylen is quite nasty. To high a temperature (or pressure), it falls apart with a **bang**

• a quite unexpectable but possible cause: if you lead acetylene through a copper alloy above 80% (brass is OK) you get . Some kind of explosive that is very sensible. Now if you have cleaned the brass parts with some chemical that dissolves the tin you have 100% copper on the surface. And you get the chemical reaction that will produce the explosive stuff. Best to clean the brass parts mecanical, not chemical.

HTH, Nick

Maybe the problem is elsewhere? What do all three have in common besides the same problem? What are all three attached to?

Try attaching them to something different and see what happens.

be aware that there are propane cutting torches that are not interchangable with acety.

Try running it in the dark and look for any leaking flame.

The common thread is they are all "salvaged" - and likely not recently maintained. If the oxygen from the cutting lance can reach the mixer, it WILL pop.Deformed/overcompressed/hardened "O" rings are a common cause of internal leakage.

Grant -

I don't have a rig, but is it a heat issue - pre-ignition. Maybe an air leak that the gas that flows sucks in air and ignites poorly.

Just guessing - but maybe an idea. O-rings might do this - if high velocity gas is flowing past.

Martin Martin Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net NRA LOH & Endowment Member NRA Second Amendment Task Force Charter Founder

Grant Erw> I've been keeping my eye on surplus oxygen/acetylene gear locally and

I took 'em out to the torch repair place today. The owner came out and looked at them all. One, two, three, same story: bad cutting tips. One had a big ding in it, another had been dropped and was visibly out of round, another was badly scored.

He also looked at the O-rings and said they were fine.

So I ordered some tips, should be here in about a week, will post a summary.

GWE

Grant Erw> I've been keeping my eye on surplus oxygen/acetylene gear locally and

Summary: 2 of the 3 were fixed simply by putting in new tips, the other one needed both a new tip and to have the head reamed. If a cutting torch lights up fine but when you pull the trigger it pops and goes out, a good place to look is at the place where the cutting tip seats into the torch. Look closely at the seating end of the tip. Look for nicks or out-of-roundness. If you find them, replace the tip. If the tip looks perfect or if the problem persists with a new tip, then look closely at the seat in the torch head. If it's scored, the head needs to be reamed by a pro with a factory reamer.

On a side note, I wonder if the torch had been one of the el cheapo sets sold by HF if the torch repair place I use would have had a reamer for it. I think cutting/welding torches, like taps and dies, are tools to not cheap out on. I've owned a bunch, but brands I like are Airco, Victor, Harris and even Marquette.

GWE

Grant Erw> I've been keeping my eye on surplus oxygen/acetylene gear locally and