cutting torch pops

I'm having trouble with my new Harris cutting torch. Whenever I try to fine tune the tip to begin a cut, the torch begins to pop. The closer I get to having the cones nice and sharp, the faster the pops become until it finally blows the torch out. If I add just a light pressure on the lever with my thumb I can get the popping to stop. I've got the acetylene set at 5-7lbs and the oxygen at 40lbs. The tip has 6290-0 stamped into it and is nice and clean. I'm cutting 1/4 to 3/8 metal. any suggestions?

 

Check for air leaks.

 

Tank settings sound good. Try opening the acetylene knob on the torch a little more before you turn on the oxygen.

 

Check the seal on your tip.

 

Try another tip.

 

I would turn the Oxygen down to 20lb. If that tip is size 0 I would step up to a 1. Find a chart that tells you tip size and gas pressure settings for different metal thicknesses. The main thing is to keep the tip perfectly clean.

 

yer suckin air someplace, tighten all the fittings.

 

Had a shop teacher fill a balloon with acetylene, at six or seven pounds the balloon exploded. To be safe lower he acetylene to lower then 5 pounds. Not trying to be a wise guy, it is a real safety issue over five pounds.

 

Dirty tip.

 

Check for air leaks and Mabey less oxy

 

Definitely too much oxygen. 20 should do it for cutting. Do you have a tip cleaner? If not they're cheap and a must-have. A clogged/dirty tip will also contribute to the popping.

Bob

 

i had a new tip do that changed it out it was fine

 

Check the nut that holds the tip. It needs to be tight. Check to make sure that there isn't anything on the inside of the nut or tip preventing it from sealing.

 

buy a tip cleaner and use it to clean the tip. Use the proper size to run down in all hole in the tip to file burrs and sh*t out of there. Gas welding 101

 

Check for air leaks, tight fittings.
I've always used 5 and 15 on the tanks for up to 1/2" mat'l just the way I was taught in HS metal shop a loooooong time ago

 

3 psi acytelene and 30 psi O2.

Are you sure you are giving the torch enough acytelene before you add the oxygen?? That is usually why they backfire like what is happening to you. You want to be working in the smoke range with cutting but not to low. A good way to get the right amount is to light the acytelene and keep turning it up slowly on the needle valve on the torch until ALL the black smoke (carbon) clears, THEN turn it back a half turn on your needle valve into the smoke range.

 

The tip is new, plus I've cleaned it repeatedly just to make sure. Whats confusing me is that I can add a light pressure on the level and the popping will stop. I've tightened everything I can find and will adjust presures as per the chart HOTROD428 posted. Plus, I'm buy another tip this afternoon just cause.........I appreciate all the help and advice. Thanks guys.

 

I would say that the tip isn't getting a good seal between the cutting hole and the pre-heat section. When the fuel gets into the cutting hole, it burns when it gets out of the tip and the fire goes back into the tip causing the popping. When you press the handle to put oxygen through the cutting hole, the fire can't go back into the tip to cause the popping sound.

 

That'd be my best guess too. I've got Smith, Victor, and Airco torches but not familiar with Harris and their tip setup. If there are gaskets on the tips, I'd check to see how they look. Usually the retaining nut doesn't have to be all that tight to seal, but, especially on a Smith torch, if someone ever cranks down on the nut like a gorilla just one time then the gasket gets deformed and overtightening is the only way it'll ever seal in the future.

 

Acetelene becmes very unstable when released to the atmosphere at greater thatn 15 psi. I don't believe you could see the difference between 3 and 7 psi.

The later replies suggesting an internal restriction or bleed from the preheat to the cutting orfices make the most sense.

 

Maybe I don't understand what you're trying to say, but I don't think what you're putting into the balloon matters. Acetylene, helium, plain air, when you get to low single digit pressure in the balloon it's going to pop.

 

Harris uses a metal to metal seal. Some of the off brand tips don't fit as well.

 

I was taught that acetylene will self detonate at over 5 psi in the atmosphere. The balloon was not over filled, about the size of a orange and it did self detonate. I have never had a regular balloon filled to that size self detonate. The point that I was trying to make is I felt the poster was getting close to a unsafe pressure.

 

I worked at a welding supply company for many years. It's 15 psi that is unsafe.

 

Rattle Trap you are correct it is 15 pounds. Sorry for my wasted post.

 

It's kinda funny this came up. When I worked there we had our own acetylene plant. You could smell the place for a few hundred yards if they were pumping. It is at the Westair store in Escondido Ca.

 

Don't forget to install check valves at the regulators to prevent any flashback from igniting the regulators themselves...if your fittings are dirty and leaking air this a distinct possibility....the check valves are sold in welding supply stores or wherever you refill your tanks.

 

is it a victor style Harris? if so try a new tip. if no avail, tighten the tip nut until it squeaks. it is a tapered fit type seal and if not seated tught the first time it will leak. if its a Harris with a flat based tip, check to see if the tip base is flat, maybe run it on a file to see. just a couple things to check....

 

Sounds like your flame is too low. If you don't have enough gas coming out (both acetylene and oxygen), the flame will actually burn back up into the tip and cause that popping sound. This happens with welding tips as well as cutting tips. If your tip is too big, so that you aren't using a large enough flame, it'll do this.

As someone suggested, get a chart from your welding supply to make sure you're using the right size tip for tghe steel you're trying to cut. Adjust the flame so that it's neutral...not too much acetylene (yellow, sooty flame) and not too much oxygen (hissing sound). Also make sure the distance you're holding the tip from the steel to be cut is correct, according to the chart. Holding the torch tip too close will also cause the popping sound (and for the same reason, the flame is burning back up into the tip because the gas isn't coming out in enough volume).

If possible, get someone who's good with a torch to watch you and give you some suggestions. Takes practice, but a torch will produce a very clean curt on steel when used properly. One last thing...that popping sound is dangerous, because if you don't have check valves on the torch, the flame can burn down into the hose. The popping can actually cause the torch to explode in your hand if you allow it to continue long enough. When you hear that sound, stop what you're doing, shut off the flame, and then make sure you have the correct tip and are using a correctly adjusted flame.

 

All three correct answers.

If the tip does not properly seat to the torch head, it will pop every few seconds.
A large crescent wrench with ample pressure applied will seal most tips unless they or the torch head has a marked or defective seat.

And, in-despite all the know-it-alls on the miscellaneous forums.

Oxy/Acetylene needs to be set to a proper/correct stoichiometry just like your carburetor.

With a carburetor, the proper ratio is about 14 parts air to one part gas -14:1.

With oxy acetlene, the proper stoichiometry is about 5 to 1.
So set up for 5 acetylene to 25 oxygen.
-Never ever set your oxygen more than 7 times that of the acetylene or you risk back burn and/or regulator explsion/damage.
Never exceed 15 acetylene or risk fire/explosion.

If using Propane/Oxy set up, the stoichemitry is about 3 oxy to 1 propane/fuel