View Full Version : Oxyacetylene question

10-13-2009, 09:38 PM
While welding with my OA setup, I occasionally get a "pop" at the surface which sends hot steel flying. I assume that it may be moisture somehow, is that right? It is very disconcerting.

I also want to make a video of me lighting and adjusting my torch in the hopes that some of you experts can help me get a neutral flame. My brother has shown me a couple of times, but once he leaves I tend to forget exactly what it's supposed to look like. And I'm not sure that he is totally sure of the right way to do it either. :)

I'm using a prest-o-lite number 9 welding head which covers 1/16" - 1/8". What might be some pressures to start out with?


10-13-2009, 10:58 PM
At least three things can cause your torch to pop. The biggest reason is getting the tip too hot by either holding it too close to the weld, or using too small a tip, which causes you to hold it too close. You can also cause it to get to hot if you are welding in a corner and get too close. The other thing which often causes a pop is having a bad tip. I have a number 2 tip on my Henrob which has been burned partially away near the end, and it definitely will pop and blow itself out. Finally a leak in the hose or torch can cause a pop.

10-13-2009, 11:10 PM
As far as lighting goes, I do all my torches the same way. I start with the Acetylene valve (the one on the torch) open about 1/4 turn and light the acetylene. Then, I open the acetylene valve more until ai get a long flame with lots of carbon. Then I back it down until the carbon almost stops. Finally, I start adding oxygen until I eliminate the feather on the small blue flame in the middle.

Here is a video that shows you the method for setting the regulators. I used the same method to set my regulators for both my Henrob and my Smith airline torches. Both came out to be around pressure of about 5 psi. I didn't need to mark my regulators, since I have a low pressure gauge on my regulators and can remember 5 psi.


10-19-2009, 07:14 PM

I tried your way of setting things up and it worked very well. Thank you.

10-19-2009, 08:44 PM
I'm glad it worked out for you. The method is as old as the WWI airframe builders. I learned it first from aerometalworker on metalmeet, then it was reinforced by the Henrob torch guys, who use the same method. The beauty is that you don't have to know much about what pressure the tip takes, and don't have to have an accurate oxygen pressure gauge, which is handy on the small antique "airline" torches I love.

By the way, the main reason you adjust for the long acetylene flame first then back it down, is because it gives you sufficient pressure to operate the torch properly. You could light the torch just by opening the regulator valves a little bit and light it, but that is dangerous, since too little pressure can cause flashbacks. Using the old method gives you a safe pressure for both oxygen and acetylene and a nice neutral flame.

Be careful not to ever open the acetylene regulator valve to exceed about 14 psi (the red zone on the regulator). Doing so makes acetylene very unstable and dangerous.

Once you have your regulators set up and marked (if you don't have a good low pressure gauge on the oxygen), you don't really have to do it again, if you don't mess with them except at the main tank valve. I usually take the pressure off my regulator valves since I can easily read 5 psi and the regulators seem accurate. Supposedly the adjustment springs last longer that way.