Torch pressures

[David G]

What do you run for acetylene and oxygen pressures on cutting torches?

Thanks,

 

[bo]

5-7 or acetylene and 30-35 oxygen

 

[NCWayne]

It depends on the size of the torch tip your using. For the 'average' tips, say 0 and on down, and the 'typical' material thickness being cut, you can get by with around 5-10 on the acetylene, and 50, give or take, on the oxygen. When you get to the larger tip sizes, and cutting thicker material (3/4 and up) the acetylene gets bumped up a bit, if needed, BUT NEVER OVER 15, and the oxygen typically needs to be bumped up in the neighborhood of 70.

 

[Anonymous-0]

4 PSI of acetylene will cut over 8" thick. About the only time you need to have higher acetylene pressure is you're using a heating tip or a very large welding tip. Really big heating tips actually require 2 or more cylinders manifolded together so that the acetone isn't drawn out of the cylinder. 30 PSI is a good general setting for most cutting. Using higher oxygen pressure just wastes oxygen. 40 PSI of oxygen will easily cut over 1 1/2" thick steel. Having the proper tip size is the key to good cuts and 60 PSI is about the highest that would ever be needed. No matter what size of welding tip or cutting tip you're using, once a straight acetylene flame jumps from the end of the tip indicates that that is the maximum pressure/flow the tip can handle. In fact that's what you use to balance a tip for O/A welding. With a heating tip however, you can have the acetylene high enough to jump the tip on its own as heating tips use the high flow to also help keep the head from getting too hot. The biggest cause of back firing, especially with a heating tip, is from not enough acetylene pressure. 15 PSI is the maximum safe pressure for acetylene.

 

[TJ in KY]

(reply to post at 19:43:51 10/30/11)

tick weld is right on. I very seldom go above 4 on acetylene and 40 on oxygen unless using a rosebud heating tip. The only thing I would add is for good clean cuts keep your tips clean and the slag I'll fall right off.

 

[NCWayne]

Working in the field on heavy equipment I rarely get to cut on nice clean material, and often I'm stuck cutting multiple layers of patches with crud in between. As such I typically keep at least a #2, and often a #4 cutting tip on my torch. I do this not so much because it's always needed for the thickness of the metal as I do to help overcome/burn off the multiple layers, rust, grease, dirt and other mess freqently found on the material I'm needing to cut. Too I tend to have to do a fair amount of piercing on fairely thick objects, such as frozen pins. Although I also have one of the small exothermic setups which works great fot the really thick or the really stubborn stuff, it's a pain to have to get it out and set it up, and it uses ALOT of oxygen so the torch usually gets first shot. I also have about the largest heating tip I can get to run off of one bottle that gets used on occasion. With that larger cutting and heating tips, and for the reasons I just mentioned, I typically run the pressures I mentioned because those are simply pressures I have found that work for pretty much all of my applications. Granted I might be able to cut back a little here and there, at times, but it's just easier for me to set the regulators once and leave them alone since I can't stand right beside the bottles on my truck with the torch in hand to get the pressures set just right everytime I change the size of the cutting tip or change over to a heating tip or brazing tip. I've been running these pressures for close to 30 years now, since I first started working on equipment with Dad when I was still in my teens, and all I know is that right or wrong, they have always worked for me.

 

[Butch(OH)]

The only thing I would add to that excellent advise is the tips need to be both proper size and CLEAN.

 

[Tony S.]

Also you can't always trust your gauges. Old ones get sticky. Get a feel for what is the right pressure.

 

[Puddles]

80-PSI. Oh wait that's the air pressure required on my plasma! :lol:

Who can afford acetylene anymore? :shock:

 

[jose bagge]

i go 4/40....easy to remember, and works ok for me.

 

[bruster]

I've always used a 4 to 1 ratio, taught at metal shop 40 years ago. this is also what most gas pipeline welders use too.

10psi acet. / 40psi oxy.
NEVER go above 15 psi on acetylene as this is where it will become unstable and can go boom.

 

[Anonymous-0]

A lot of people don't know the proper way to use a tip cleaner either. Puddles posted a picture a while back of a perfectly clean tip. With the cutting lever depressed you should get a long straight feather with 2 distinct lines right down the center. If you keep your tips in good shape, you should only need to put a tip cleaner in each hole once every once in a while. Over cleaning can oval the holes. When I have my torch tip clean and set right, it makes more noise when cutting, kind of like it's singing. I think the extra noise is an indication it's set up perfect. No slag on the bottom at all and almost like a thin layer of mill scale on the cut. No grinding required at all.

 

[Fred Martin]

If we're gonna mention the safe things for a new torch operator, we might as well tell them to always keep the bottles standing up and use flash back adapters in line. And always look around for bombs before using the striker. You're actually supposed to transport oxygen bottles with the cap on the bottle. ohfred

 

[Puddles]

I'm not that good with a torch, never have been. I've worked with a few guys over the years who were amazing with one. One thing about a torch that most people don't realize, everyone of them is different. And they all have a sweet spot, just like a Mig welder. Most people press the oxygen lever all the way down, I can't ever remember hitting the sweet spot by doing that! Generally its only a 1/4 of the way, or maybe 1/2. As with a Mig welder, you have to find that sweet spot! :wink:

 

[John B.]

Sounds like everyone has covered your question quite well. But one thing that wasn't mentioned is that an owner of a welding firm once told me, never let either of your tanks go empty, this allows the other gas to seep over into the empty tank if your torch head is leaking...