View Full Version : Oxy Torch and Pressure
01-13-2004, 09:08 PM
I'm looking to replace my cutting torch with a bigger model, the local welding supply sells Victor torches. Are they a good brand?
Also what pressures do you run your torches at? I use 20psi oxy and 5psi acetylene.
01-13-2004, 09:48 PM
Smith ,Victor and others. I've had a Victor (small one ) for about 15 years still works fine and I've never done anything to it. David
victor are great- cheap to fix if something goes wrong 3 and 30 is a pretty good rule of thumb what size tip you cutting with
01-14-2004, 12:24 PM
Based on absolutely nothing more than Physics,
the ratio of Oxygen to Acetelene should be 4 to 1, or any multiple thereof.
What you set the regulators at is more a function of hose size and length as well as torch size than anything else. The valves on the handle take care of the rest of the setting.
01-14-2004, 10:41 PM
I've got a Victor medium-duty outfit, and I very much like it.
My "rule-of-thumb" is 5 and 5 for welding tips....and
5 and 25 for cutting tips.
the pressure ratio for gas welding is 1 :1.1 meaning if you have a number 3 tip you should have 3lbs of acetylene and 3.3 lbs of oxygen- setting pressures and learning how to balance a torch are probably one of the most important things you can learn. Your not likely going to blow yourself up playing with your mig but you might do some damage if you don't take the time to learn about pressures and how a regulator works. I can't stress the importance enough. Learn how to balance a torch, don't rely on flashback arrestors there good but not foolproof. take this to heart and you will live to thank me
sorry I should add that the 1 : 1.1 value is approximate some man. will state 1:1
SOME IMPORTANT THINGS TO REMEMBER:
always purge hoses before lighting, purge each line independently oxygen first then fuel gas.
never use oil or grease on oxy-fuel cutting equipment= bad news
there are plenty more to remember but hate to preach
01-16-2004, 01:13 PM
Victors are a great torch. They have been the standard for aircraft maintenance for many years. I especially like the small models where the adjusting valves are on the top end rather than on the bottom end of the barrel, where they constantly get mis-adjusted by your gloves, etc.
Anyway, while we are preaching about safety with O/A , it won't hurt to repeat the warning for our newer members about keeping the acetylene bottles upright when welding. The bottle is filled with a vermiculite-type material and acetone, into which the acetylene is soluble, like CO2 in 7-Up. By itself, acetylene is extremely dangerous if compressed over 15 psi, which is why it is dissolved in acetone. Get that baby sideways, and it may spit acetone and do all sorts of nasty things, including moving your shop to the next county.
Quoting one is plagiarism. Quoting many is research!:blob2:
01-17-2004, 10:32 PM
Just to add to everyone's great responds. Something overlooked by a lot of people are the valves on the tanks.
Open the Acetylene valve only 1/2 turn, and the Oxygen valve all the way. The Oxygen valve is a double seat valve and needs to be open all the way. The Acetylene valve should be open only 1/2 turn so that you can quickly close it in case of emergency.
Not everyone knows about the valves, this is just to help the ones that don't know.
01-17-2004, 10:49 PM
Thanks, slagking ! . . .and to take that one step further.....
I'll tell you something that's hard to believe !
Years ago, (or, as Franz would say: "once upon-a-time"), ...
When I was in high school, of course we had metal-class.
NEVER.....ABSOLUTELY NEVER, did our instructor tell us NOT
to turn the pressure up on the Acy. over 15 p.s.i.
As I remember, he told us to set for 3 on the gas, and 15
on the o2......but there was never anything said about the
unstableness of acytelene !
01-18-2004, 12:11 AM
Instructor probably didn't know. I've seen regulators set above 15 on rigs with long hoses, especially people who use 3/16 hose cause they want extra flexability.
I've got so damn cantankerous I carry a small Smith set with me, that is on the ned of 3' of 3/16 hose I can couple to the hose where I'm working. Most people who have torches of their own, have ****ty torches that haven't been cleaned in years, and I flat refuse to try workin with that level of equipment.
I've seen my Old Man fire people for leavin a torch lay on the floor when they weren't usin it, and the older I get I think he was onto something. Anybody who don't care for a tool properly oughta be workin with somebody's tools other than mine.
01-18-2004, 12:24 AM
True for you, Franz ! Sometimes I feel a little foolish because
I treat my torch very kindly, and when I see workers out there
dropping their equiptment on the ground, torch is filthy,
hoses are leaking, regulators all banged up.....and the damn
thing is still working....I feel i'm being "over-careful"..........
01-18-2004, 08:09 AM
Acetylene is some tricky stuff. As was stated it is kept dissolved in acetone in the tank. The kank is filled with a porious media to help keep everything stable. Gaseous acetylene above 15PSI can " disassociate into its basic components of Carbon, and Hydrogen. This is extremely unstable and explosive:blob2:
You guys that bought sets check to see if the set included check valves between the torch and bottles. If you don't have them get a set at your first opertunity, a flash back in your torch that gets back to the Acetylene bottle will definetly ruin your day.
The regulators, hoses, and torches all seal with a "union type" seal DON'T USE ANY PIPE DOPE SEALANT OR TEFLON TAPE OF ANY KIND.
DOB was right on with welding torch pressures. But guages being hard to read, I just use equal pressures.
For cutting torch pressures. Manufactures have recommended pressures for different size tips to get the best results. The instructions that came with your torch should have a chart. Or you can go to the Mfgr's webb sight and get recommended pressures.
Get a good book on welding.
Richard Finches isn't bad for a basic, although he's a little full of himself. Welding essentials from Industrial press is another good book.
I haven't seen the Wall Mountain video yet, but if it's as good as the Mig video, it would probably be worthwhile.
I believe Marco plol is on the right track "be over-careful"
thats my 02 cents:waving:
01-18-2004, 03:59 PM
I agree with everyone, always be careful. I don't know what I would do without some of you being able to share all the knowledge and fun of welding. Thanks for all the safety hints and concerns. I always try to follow all the them and I always try to learn how to be more careful. I don't want to lose the new skills I have, or the joy of working with my hands and mind by doing something wrong that I know I shouldn't be doing. Updates and refresher's are what I need and I'm sure it's good practice for everyone to take a few seconds and just think.
02-11-2004, 01:12 AM
yes you want victor.bigger torch? straight or handle & attatchment?..
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