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Old 06-02-2010, 11:55 AM
rustychrome rustychrome is offline
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Default Stupid questions for an oxy/acy newb

I'm not new to an oxy/acy rig, but I have found recently I didn't know as much as I thought I did. I have read lists everywhere regarding safety and feel pretty well educated now and feel like a bomb technician every time I approach the bottles. I have a couple of questions I haven't seen answered.

Obviously, you don't use any oils or lube on the threads. I figured I could just use some soapy water in a spray bottle to check for leaks. I suppose a few drops of dishwash soap in a spray bottle is fine, right? (I questioned this after somewhere reading to make sure you are using an "approved" leak detector formula)

In the past I used teflon tape, but now I hear that is wrong. I think I've got my fittings as tight as they will go, but I know I am still leaking acy at least. I can smell it around the gauges. These are brand new regulators too BTW.

Also, what causes popping when trying to light? As soon as I start to add the oxy to the already lit acy, it pops and extinguishes.

Last edited by rustychrome; 06-02-2010 at 12:41 PM.
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  #2  
Old 06-02-2010, 02:37 PM
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Machinist-Guide Machinist-Guide is offline
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Default Pop

Can't really say about the leaking issue but the popping sound maybe the ox blowing the flame away from the tip. Try turning the gas valve up a little more before turning on the oxy. Or drop the oxy pressure a little
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Old 06-02-2010, 06:00 PM
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The popping could be a lot of things, if there is a gap between your tip and gas flame it will pop and go out or if your tip is not seated it will pop and go out.
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Old 06-02-2010, 06:58 PM
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I've been using A/O for years. My friend came by the other day while I was cutting something and he noticed when I turned off the O and the A that there was still a small flame on the tip. I blew it out.

His comment was just this. Wow, seems like everyone I know has this problem. I said yup, after the first year it seems to be normal. He said yup seems to be... He was a licensed pipe fitter years ago.

The reason I am sharing this is because if there is any O2 left in the line or is leaking out of the tip while you are trying to light the torch it will backfire.

I keep trying to egg him on to show me some stuff and maybe 3 months ago he came by to try try his hand at welding some alum on my Dynasty 350. I set it up and laid a few beads, handed him the torch and said have fun.


He gave it a try for maybe 10-15 mins and said" Well, I guess I can't give you a hard time about your beads anymore"!!!

I said yeah, the machine is a little different than the old sinewave jobbers. He said sure is. Said to stop by his work so he could show me how to lay some bead with his old heliarc machine.
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  #5  
Old 06-03-2010, 05:01 AM
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Default What brand Regulators?

I have on occasion picked up O/A cylinders at my LWS and have received a bad valve. The packing around the shaft on the cylinder was bad, or, there was a "burr" in the seat area of the valve, where the regulator male end goes. It wouldn't "smell" while the valve was turned off, but leaked when opened.

Could be a leaking regulator.

The popping can be as one poster stated, or, outside air being sucked in the line through a leak (while the torch is lit)

I once had a devil of a time welding a customers mower deck. Brand new Airco setup with 2 stage regulators. The tips leaked where they were screwed in at the factory (each size tip came with it's own mixing chamber nut). I called Airco, they replaced them.
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Old 06-03-2010, 02:23 PM
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I have all but given up trying to teach the guy's at work how to properly set pressures, light, and shut down an Oxy/Ac torch. Even though I have shown them, they just do not get it. Maybe I am a bad teacher and need a different learning approach. Once they get the torch lit, their cuts look like they don't have a clue as to how to adjust the torch. We have a Journeyman torch. Does anyone know of a good source for instructions (very explanatory) or can list the proper way to do the above...........thanks
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Old 06-03-2010, 02:35 PM
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Quote:
Originally Posted by Pat View Post
I have all but given up trying to teach the guy's at work how to properly set pressures, light, and shut down an Oxy/Ac torch. Even though I have shown them, they just do not get it. Maybe I am a bad teacher and need a different learning approach. Once they get the torch lit, their cuts look like they don't have a clue as to how to adjust the torch. We have a Journeyman torch. Does anyone know of a good source for instructions (very explanatory) or can list the proper way to do the above...........thanks
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Old 06-04-2010, 05:17 AM
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Quote:
Originally Posted by rustychrome View Post

In the past I used teflon tape, but now I hear that is wrong. I think I've got my fittings as tight as they will go, but I know I am still leaking acy at least.
There is a special Teflon tape for use in oil free environments such as oxy it is a yellow green colour ) Do not use teflon on the bull nose regulator to cylinder coupling.It is used in reassembly of a repaired gauge. Some bull noses - newer ones have an O ring on the bottom ,but the older ones do not.

Also, what causes popping when trying to light?

The acetylene knob on the torch is generally not open enough. Not enough volume As soon as I start to add the oxy to the already lit acy, it pops and extinguishes.
You need a nuetral flame ,ie equal amounts of oxy and acetylene )
Also check the cutting nozzle seat for nicks and scratches.They can get banged about in tool boxes. I am a shop teacher and have just spent the best part of the day teaching this very thing.

Getting a newbie (student or otherwise) to check that the nozzle size suits the plate thickness can be the pits.

Most set the flame temperature way too high and melt over the plate edge.

A good way to tell is to "listen" to your flame.If too hot it roars and you have to raise your voice to talk above it. A correctly set flame is soft and therefore the pre heaters will be set low enough not too overheat and melt your plate edges.
Your plate edge will be square and sharp if you set the flame ok.
I can scribe a circle with my dividers, center pop the circumference and then split the centerpops around the circle periphery,in half. I'll do a piccy for ya next week at school if you blokes want.



Have a good weekend fellas
cheers
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Last edited by OZWELDER; 06-04-2010 at 07:26 AM.
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Old 06-04-2010, 07:54 AM
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Quote:
Originally Posted by OZWELDER View Post
I'll do a piccy for ya next week at school if you blokes want.
This bloke would really like to see it. Thanks for the offer.
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  #10  
Old 06-04-2010, 10:45 AM
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I had the pdf below in my archives. Might help someone. Be mindful that it is nearly 8Mb!

Do not use teflon tape or any other kind of sealant on the threads or connection of any kind of ball/flare fitting. On a torch or otherwise. Despite your best intentions, the tape can get on the sealing surface of the fitting and actually cause it to leak! Or it can get inside and cause issues. DO inspect the sealing surface for pits, debris or cracks and repair as necessary.

The best way to check for an acetylene leak is right there hanging off your face. You shouldn't smell it near the regulator at all. What I usually have found is that the connection at the cylinder is the source. Simply retighten or maybe remove the regulator and check the sealing surfaces of the fittings. Sometimes the cylinder valve will leak when open which can be repaired by slightly tightening the gland nut a little at a time until the smell is not present anymore.

Oxygen leaks will have to be found with soapy solution but they are at a higher pressure so it is a little easier.

Some other tips are:
* Keep a supply of torch handle o-rings around--they dry out from the heat and can cause the handle to catch fire when they leak! (turn off the valve at the cylinder immediately!)
* Keep hoses away from hot slag and be mindful of where your sparks go when you cut
*15psi/5psi O/A is a good pressure starting point for welding. 20psi/5psi for cutting. Always "ease" the cylinder valves open, nice and slow. Adjust regulator pressures with the torch valves open.
* I open oxygen all the way to the back seat. Although some may disagree, I only open acetylene about a 1/2 turn so it is quicker to turn off in an emergency.
* To start, crack the acetylene at the torch handle ever so slightly until it will take a flame, then increase the flame until you get "paratroopers". Gently add oxygen to the desired flame is achieved. Fine tune acetylene as necessary.
* To shut down, ease off the oxygen, then the acetylene on the handle valves. It is not uncommon for the remaining acetylene to "burn off" for a few seconds afterwards. Then close the cylinder valves.
* If you are done for the day, bleed the hoses, then back off the regulator adjustments. Hang the hose up and avoid walking on it or rolling things across it.
* If you plan on using the torches later on, pay attention to the pressure remaining on the regulators when you return. If the pressures have dropped significantly, you probably have a leak somewhere.
Attached Files
File Type: pdf victorcutguide.pdf (7.96 MB, 350 views)
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Last edited by mccutter; 06-04-2010 at 10:54 AM.
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