The Stovebolt Site Forums The Shop Area The Tool Chest Oxy-Acetylene 101

Okay, it's been a VERY long time since I used an oxy-acetylene setup and I can't remember what pressures I should set the two gasses at on the gauges.

Any help is appreciated.

Woody,

Different welding and cutting tips require different settings. For some reason I was taught (in high school shop) to set my acetylene at 6 lbs and the oxygen at 25 lbs. I have always done this and it works well for almost any tip I use.

If you use a giant rosebud or a 000 welding tip you will automatically see the pressures need to be adjusted, either up or down. 6 and 25 is easy to remember for my pea brain!

Stuart

Thank-you,Stuart. Ive been in the same limbo as Woody.

For anything except cutting of very thick steel, 5 lbs. of Acetyline pressure and 10 lbs. of Oxygen pressure has worked for me for nearly 50 years. NEVER get gaseous Acetyline above 15 PSI- - - -it gets unstable and potentially explosive. It can be stored at around 250 PSI in the cylinder because it's dissolved in liquid Acetone, and the cylinder is filled with a porous material to prevent the liquid from sloshing around. Never lay an Acetyline cylinder on its side, as the Acetone will clog the regulator and result in erratic pressures and liquid into the welding tip.
Jerry

Thanks guys!

if you are welding instead of cutting i bet they have a webpage that tells the pressures for specific tips. when welding you commonly set the pressures closer together than cutting. i have a small book put out by victor that tells the recomended pressures for specific welding tips and i could look up any specific one you need. or like i said they prob have them listed on a website. for cutting the setting mentioned will work great.

Woody,

Since the early '60s I have used 3:1. Three parts oxygen to one part acetylene, then "deoxydize" the flame by getting rid of the fine blue "fuzz" and leaving a sharp blue point. From the point of the blue flame back about 1/3rd of the flame length is the hot part you'll want to work with. Also, try to use good American coat hangers instead of the poor quality Chinese ones.

best wishes,

Les

Not to argue with Hotrod, because what he said about not laying a Acetyline bottle on its side is correct. I know it, but I do it all the time. I let it sit for at least an hour before I put the regulator on. With the regulator still loose, I crack the valve to purge the connection.
The one thing I never do is transport any bottle with the gauges on. Unfortunately, I see it all the time.

People don't realize that if you break the fitting off a compressed air (argon, shielding gas, oxygen, etc) bottle the pressure inside is so great it becomes a projectile and will rocket along the floor doing a lot of property damage and personal injury if you get in its way.

NEVER transport a compressed gas cylinder unless it has the steel protective cap on... that's why they make those things.

I'm glad I learned my trade in the military where they drilled safety into your head. I go into shops around here and wonder how people have survived their ignorance.

my training was- if a high pressure pressure bottle falls and the fitting breaks...... jump on it and ride it like slim pickins yellin yeeee hawwwwww. i checked my victor book a size 2 tip for welding 1/16" to 1/8" o2 pressure= 5 psig, ace pressure= 5 psig. for a #4 for 3/16" to 1/4" is o2= 10 psig, ace= 7 psig. in fact size 000, 00, 0, 1, and 2 all call for 5 psig of each ace and o2. but i'm sure most everyone just about what ever you set it on the actual adjustment is made at the torch. in fact you can open the torch valves and do the adjustment using the gauges so it prob doesn't even matter what you set them on as long as it's enough but not too high to be dangerous.

Czechman you are so right with that statement so many people do not respect what can happen when a nozzel is broken off a Oxygen bottle. 2200lbs per. sq. inch is spewed out such a small orfice and able to go through a building or a block wall and even a automobile. When I was in a machine-welding shop class during high school they showed just that same destruction I just descirbed before it exhausted it's fury. Being in the trade for 41 years I had a experience while building a tubing framed catwalk. We were putting up a set of stairs to the walk after cutting-trimming to fit the steps the cutting torch managed to end up in a 10" x 8" gutter with the acetylene valve barely open. We took a 10 minute break and came back to work ready to weld the steps in, now being a winter day the gas was down in the gutter and we did not smell it. My helper was holding the steps when I struck the arc on the metal catwalk-steps needless to say what an explosion we had. It was load enought that the superintendent came out of the main office along with other maintance personal coming to see what happended to us! By the time everyone got there we were back working just as if nothing happended. Being in a old aircraft hanger the sound was magnified. If that gas would of been in a tank or closed gutter we could of had some shrapnal flying around. So take it from one who has been there BECAREFUL with Cutting,welding tanks under pressure!
62Blue
Don

You can leave your regulators set for cutting pressures and just 'feather' the valves to get the required flame for your welding tip, but trying to needle down 20 psi of oxygen to 2 psi for a #0 welding tip is touchy at best.

I have a Smith torch set and have a hard time getting consistant pressure regulation below 5 psi. I have heard of dual stage regulators and I suppose that is what I need to properly regulate my pressures, but for now I am getting by.

Racecar I do not recommend turning off your tanks with the preasures set for cutting as this puts undo strain on the regulaters diaphragms when you open your tank valves. Two stage regulators is the way to go here but all pressures must be backed off the diaphragm for safety reasons as well to preserve the bellows in the reg. valves when opening the tanks main shutoff valve. You should "ALWAYS" shut off the main valve and back off the pressures! Each time you use the tanks you should reset the gages.
62Blue
Don

I know, I'm bad about not backing off the regulators! But, I'm very good at being able to "crack" open a valve and let the pressure build veerrrryyyy slowly in the regulator before opening it up all the way....

I run my regs at 6 & 30 when I'm cutting. I don't weld with my rig as I don't know how! Although I do braze occasionally with it... I set it at 15 & 6 then... Just where I stick it.

No need to open the Acetylene bottle all the way. In fact it is not recommended. Just open it one half to one full turn. This way, if something catches fire, the Acetylene bottle can be turned off quickly.

Right, I new that... By saying all the way, I meant all the way to the service position. I only open my acetylene bottle 1/2 turn and my oxy bottle about 1 turn.......

Depending on which oxygen bottle you get the bottle was supposed to be opened all the way but some of the new ones have a different valve mechinsim so they do not have to be opened all the way. I should clarify the Acetlene bottle has the different mechansim.
62Blue
Don

The valves are double seated. they need to be fully open or fully closed to seat properly, or you may leak past the valve shaft packing.

I have been using 5-7# AC to 15-17# Ox for years and adjusting the torch as needed

A few things discussed above and a few not: Always back off the regulators, always transit with the protective caps on, cinder block doesn't stop a CO2 tank with the valve busted off (but the water heater does), Never transit in a closed trunk, never oil a regulator, always know where your hose is, know what is on the other side of what you are cutting/welding, keep the fire extinguisher handy.

Way back when I took welding in high school they taught not to open the acetylene valve all the way. Open it one turn or less in case it needs to be shut off quickly.

A Google search for "Oxy-Acetylene safety" turned up a bunch of references. I chose http://www.metalwebnews.com/howto/weld/weld.html It says 1 to 1½ turns.

It also lists recommended pressures, lens shades and other helpful info.

Their list of safety rules:
"Never use Acetylene gas at a pressure over 15 psig.
Never use damaged equipment.
Never use oil or grease on or around Oxygen equipment.
Never use Oxygen or fuel gas to blow dirt or dust off clothing or equipment.
Never light a torch with matches or a lighter. Always use a striker.
When opening a Oxygen or fuel cylinder valve, always crack it open first.
Always make sure regulators have their adjusting screws released by turning them counter clockwise till free before opening cylinder valves. Stand to the side of a regulator, not in front of it when opening cylinder valves.
Always wear the proper welding goggles, gloves and clothing when operating Oxy-Acetylene equipment. Pants should not have cuffs.
Always have a fire extinguisher handy when operating Oxy-Acetylene equipment.
Always replace cylinder caps when finished using cylinders.
Do not rely on the color of the cylinder to identify its contents as some suppliers may use different color codes.
Always use the proper regulator for the gas in the cylinder.
Always use cylinders in the upright position only.
Never store cylinders in temperatures over 130deg. F.
Always keep the valve wrench on the Acetylene cylinder valve when in use. Only open valve a maximum of 1 1/2 turns.
Do not carry lighters, matches or other flamable objects in pockets when welding or cutting.
Always be aware of others around you when using a torch.
Becareful not to let welding hoses come into contact with torch flame or sparks from cutting."

I also would like to add some other things here Cletis always store Acetylene and Oxygen bottles seperate from each other and marked with a piece soap stone Id ing the full from the emptys. We had a rack to keep them seperate or some places use a chain bolted against the wall. That is how I keep my extra bottles with a chain that way you can't knock them over and damage the bottle or break off the valves in your bottles on the cart. Some people use chain but I made mine out of rounded flat hinged on one side with a through bolt on a piece of chain on the other side. I also have made a smaller half rounded for use with smaller bottles.
62Blue
Don