cutting torch pops

[94hoghead]

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?

[porknbeaner]

Originally Posted by 94hoghead

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.

[Jedidiah]

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

[Rattle Trap]

Check the seal on your tip.

[65standard]

Try another tip.

[Kiwi Kev]

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.

[hotrod428]

yer suckin air someplace, tighten all the fittings.

[designs that work]

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.

[Human Fly]

Dirty tip.

[Morgan91]

Check for air leaks and Mabey less oxy

[bobss396]

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

[bbc 1957 gasser]

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

[Engine man]

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.

[JD Miller]

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

[BobF]

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

[hooliganshotrods]

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.

[94hoghead]

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.

[Engine man]

Originally Posted by 94hoghead

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.

[metlmunchr]

Originally Posted by Engine man

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.

[GearheadsQCE]

Originally Posted by designs that work

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.

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.