OA Torch Setting

[Northweldor]

Just reading over some recent posts, and noted some misinformation and misunderstanding on this topic.
To clarify, balancing gases is NOT to be done when OA-CUTTING! Cutting pressures are usually set with the manufacturer's table of thickness of metal and resultant tip size, and pressures of each gas, modified by other factors that may cause loss of pressure (arresters, check-valves, hose-length, poor gauge accuracy).

Balancing gases, however, is a method used by experienced OA weldors in the OA-WELDING process to compensate for loss of pressure factors, and increase safety. For those not familiar with the process, here is my archived description again.


Balancing Gases In OAW
By M R Tebo - C. 2005

Back in the” old days”, before the widespread use of check valves and flashback arrestors, beginners were always taught to balance gases. This is a procedure I still use today, not only because of safety, but because it is a good way to check on the current condition of your equipment, and guarantees the correct setting with any tip size or regulator gauge peculiarity. With a little practice, it only takes a minute, and accurately gives you the proper setting with any make of equipment, with the max. and min. of the heat range of any tip. The instructions I usually give an OAW beginner are below.

With both bottles on, and regulator adjusting screws turned out (“off” position), turn the acetylene torch valve wide-open (3 half turns is usually enough). Then, turn your acetylene regulator adjusting screw in until gas starts to flow and light the torch. Continue to turn the adjusting screw in until the flame just blows away from the tip, then back off the screw until the flame just returns to the tip. Your acetylene pressure is now set for that tip.

Then , open the oxygen torch valve wide-open (3 half turns) and slowly begin to turn your oxygen regulator adjusting screw in until you you have a blue feather extending from a blue cone at the tip. Continue to add oxygen until the feather just disappears into the inner cone, giving you a neutral flame. You now have the torch set for maximum heat for that tip. (Wiggle both torch valves at this point to make sure you have them wide-open: if you do the flame will not change)

Finally, turn your oxygen torch valve off. Then, close your acetylene torch valve until the yellow flame starts to produce smoke, and immediately open it just so it is not smoking. Slowly open your oxygen torch valve until you again have a neutral flame , and you now have the minimum flame you can use on that tip without backfires.

This seems like a lot of trouble, but only takes 1-2 minutes with practice and only needs to be done once unless tips or regulator settings are changed. Also, note that at no point are you depending on or even looking at regulator gauges, which can be very unreliable when abused. This method will work with all standard OA equipment for welding.

Last edited by Northweldor; 10-08-2005 at 05:51 AM.

[caldwellcpl]

Thank you for posting that very clear description of how to establish the correct pressures. At first it didn't make sense, but as I continued to read it became perfectly clear. So to others, don't stop reading half way through.

Its always a great day when I learn something new!

Bob

[mikecwik]

i dont use o/a very much but had a little braze job today so i thought id try this method. im not sure what exactly the difference is if you use the torch valves to control the flow versus the regulators. i ended up with a much quieter flame than i normally have which was more to my liking.

[Northweldor]

i dont use o/a very much but had a little braze job today so i thought id try this method. im not sure what exactly the difference is if you use the torch valves to control the flow versus the regulators. i ended up with a much quieter flame than i normally have which was more to my liking.

Basically, the difference is that you are using the regulators to establish the true maximum flow of both gases for that tip, not what the gauges say is coming out of the bottles. Then, the torch valves are used to control the flame between maximum and minimum. Also, the unseen difference is additional safety, since while you can still get a backfire or burn-back by turning your acetylene below minimum flow or other causes, this won't turn into a flashback, because the actual pressure between the two hoses is balanced at the mixer and can't back up into either of the hoses.

[usmcpop]

It would be interesting to compare the pressure (or flow) settings resulting from this with the manufacturer's recommended settings for a particular welding tip.

[Northweldor]

It would be interesting to compare the pressure (or flow) settings resulting from this with the manufacturer's recommended settings for a particular welding tip.

I've done this, and they are usually just slightly higher on both gases with medium duty Victor (built-in) torch arresters and regulator-mounted Victor arresters, 25' of hose and brand new equipment. Have not done it with a flow-meter though, and might be considerably higher if check valves with stronger springs are involved, as with heavy-duty equipment, used mainly for high-pressure cutting, rather than welding. If guages are old and have been mistreated , discrepancies both high and low are usually noted (which, as I mentioned, is another good reason to use the procedure).