cutting torch backfire aka torch pop

I have a chinese made, "Harris Type" cutting torch that is only about a month old. Recently, I've been having problems with the cutting attachment popping and extinguishing the flame.

I'm using 3PSI acetelyne and 15PSI oxygen on my regulators. I fully open the oxygen valve on the torch body, but have it completely closed on the cutting attachment. I open the acetelyne valve just so an audible hissing can be heard, and light it. I increase the acetelyne until the soot is minimal and the flame is fanning fairly well. When I start to add in the oxygen with the valve on the cutting attachment, the flame sound becomes very strong and it pops very loudly, filling the air with pieces of black soot. Most recently when I lit the torch following the same procedure, when I began to add in oxygen it sounded like it was going to pop, so I turned off the oxygen, then the acetelyne. Two or three seconds after the torch was completely off, the tip popped with a loud snapping sound. Though the tip doesn't look terrible dirty, I've cleaned it thoroughly, yet I'm still having this problem.

Any ideas anyone?

Thanks in advance,


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I would go up to 5 or 6 on the acetylene.....even the oxygen could go up to

20 to 25...what size tip?

The tip might be clean but it helps to replace it...sometimes you will get a bad seal on the tip to the head

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you might have a leak in either your hose a valve or the guage..I would check that out first

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The popping you heard was because you turned off the oxygen before the acetylene. The flame then travels back into the nozzle and pops as it goes out. The problem with starting the flame is probably due to air in the oxygen pipe. Open the oxygen trigger to purge the pipe for a few seconds then try again. If this happens every time you re-light the torch after a lay off, check for leaks on the oxygen line allowing air in.


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John Manders

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