Black Smoke from Acetylene

**vwguy3** · 01-14-2011, 02:59 PM

The directions are a little mis-leading.Burning acetylene without oxygen will give smoke and soot but as you increase the acetylene flame it will stop sooting but will still smoke.As soon as you start to add oxygen the level of smoke diminishes until you reach the point where the flame burns clean.

**mikecwik** · 01-14-2011, 07:46 PM

victor manual states the same thing..."continue opening fuel valve until flame stops smoking." i can see where that would throw a brother off.

**MichaelP** · 01-16-2011, 01:45 AM

Use a different approach. After you ignite acetylene, continue opening the fuel valve until the flame separates from the tip. Then close the valve a bit till it returns. At this point you can open the oxygen valve and use it to set the type of flame you need (neutral, most often).

**joatmon** · 01-16-2011, 10:20 AM

Originally Posted by Bob the Welder

The black smoke will never leave completely. I assumed he was referring to getting rid of the big "floaters".

I think Bob the welder nailed it about removing the "floaters"! That's the way I have started my torches for years....

**4sfed** · 01-17-2011, 08:18 AM

Originally Posted by joatmon

I think Bob the welder nailed it about removing the "floaters"! That's the way I have started my torches for years....

I called Smith Equipment this morning and they confirmed that description. It's also the setting that produces the gas consumption for individual tips as listed in the Owner's Manual.

Jim

**MichaelP** · 01-17-2011, 02:31 PM

IMO, the "no floaters" range is too wide and poorely defined to be a reliable indication of an optimal acetylene flow for a given tip. It's not like it doesn't work, but I'd suggest you to start with the method I mentioned above to get an idea what optimal flow is.

**4sfed** · 01-17-2011, 03:30 PM

Originally Posted by MichaelP

IMO, the "no floaters" range is too wide and poorely defined to be a reliable indication of an optimal acetylene flow for a given tip. It's not like it doesn't work, but I'd suggest you to start with the method I mentioned above to get an idea what optimal flow is.

Use a different approach. After you ignite acetylene, continue opening the fuel valve until the flame separates from the tip. Then close the valve a bit till it returns. At this point you can open the oxygen valve and use it to set the type of flame you need (neutral, most often).

I agree the "no floater" threshold is somewhat vague, but your method will produce a gas flow greater than that recommended by Smith. Obviously, there is a range of fuel flow that will work. Your thoughts?

Jim

**usmcpop** · 01-17-2011, 03:43 PM

Check out the videos I posted. The first one mentions "most of the smoke", getting the acet flame down to the tip and adjusting a torch within a small range of heat output.

**MichaelP** · 01-17-2011, 11:58 PM

Originally Posted by 4sfed

I agree the "no floater" threshold is somewhat vague, but your method will produce a gas flow greater than that recommended by Smith. Obviously, there is a range of fuel flow that will work. Your thoughts?

Jim

Jim,

This will be about the ideal flow for many (if not the most) situations. Naturally, you can work in a range of fuel flow, just remember that it's safer to err on a high side to prevent popping and flashback.

**4sfed** · 01-18-2011, 08:38 AM

Originally Posted by MichaelP

Jim,

This will be about the ideal flow for many (if not the most) situations. Naturally, you can work in a range of fuel flow, just remember that it's safer to err on a high side to prevent popping and flashback.

I do a fair amount of heating with a torch where your method would work well. It's also appropriate for welding ferrous metals, but I think the flame adjusted that way is too forceful for silver solder, bronze welding, and aluminum brazing and welding . . . which are my main uses for a torch.

YMMV,

Jim

**MichaelP** · 01-18-2011, 10:44 AM

It's quite likely. Or, maybe, you just need a smaller tip or even a smaller torch for your purposes.

P.S. I just realized I confused you with the OP.

**Roger** · 01-18-2011, 10:54 AM

What I found interesting about the Smith videos was how he adjusted propane cutting torch. I have used MAPP Gas for cutting with same type cutting tip but after seeing that I wasn't using enough gas.

**omair** · 02-03-2011, 01:29 AM

acetylene/oxygen is the best thing to cut the steel according to the requirement but it need some sort of care as well with the technique. here is the link to use best of it...

http://www.wikihow.com/Use-a-Cutting-Torch

**mb_welder** · 03-02-2011, 11:52 PM

Airborn floaties are carbon, aka, the ever elusive Shop goblin. Add oxygen and they go away. S'funny that! Common cutting pressures are 7 and 40. Dial in the acetylene until the floaties go away, and add the oxygen. Easy!