Light weight cutting torch backfiring

[Bsmith]

Yeah but that's not what we call backfiring, what your doing is simply blowing the acetylene flame out with too much oxygen and maybe a bit of other contaminates in the oxy hose to begin with. Increase acetylene to around 5psi, oxy will be fine at 30psi. Purge both acet and oxy through first, turn on and light acetylene as has been said, get decent flame with little smoke (not soot flakes), then turn on oxygen very slowly and bring to neutral flame.

 

[dom501]

Thanks for all the advice folks, since getting all my kit set up I've noticed the manufacturers pressures are all slightly off, so I tend to use them as a guide line and adjust to suit. When I've got good settings for welding and cutting I'll write them down in a little notepad that I keep in my toolbox.

Dom

 

[Daveville30]

I had nothing but grief with a oxy/acetylene set few months back turned out it was a screw on the torch was loose .

 

[dom501]

I had another go with it today, 2psi is recommended Acetylene pressure but it's not quite giving off a soot free flame so I turned it up to 3psi which seems fine (no soot).

Recommended Oxy is 30psi which is either way too much or there is something wrong. I did the same today starting at 30psi and pop! no go, I took it down to 25psi same thing happened... 20psi same again.
At 15psi (half recommended pressure) it starts getting interesting and a bit scary, as soon as I turn the Oxy it pops (like a mini backfire) as I reduced the flame it just kept popping the more I increased the Oxygen. That's when I shut down as I'm certain this would of resulted in a sustained backfire.

Thanks for all of the replies

 

[Bsmith]

Think you may have either got a propane (2 parts)? or knackered nozzle on the torch. Have you got a spare nozzle to try?

 

[Kent]

Check you ain't got a blockage and the nozzle is still good. After that it's hard to say from description, could be a few things. Get some hands on help if you can

 

[WorkshopChris]

Are both of the O rings in good condition where the cutting torch fits to the welding torch body?

 

[dom501]

Both o rings are in good condition, what i have noticed though is when I take the nozzle off there is a half moon shape of black soot around the back of the nozzle.

 

[Bsmith]

I've had the occasional new nozzle that wouldn't work, went pop and extinguished while setting the flame after turning oxygen valve on.