Thread: LPG heating torches - latest info??

Some more info would be great Dean.

Ew

Originally Posted by Oldneweng

Thanks Rob. Not much good then.



Air is 20.9% oxygen. Much different to that and we don't enter a tank!

I have an Oxy Lpg welding set. My opinion is that it works fine for everything except steel welding. Not quite enough heat for that. This is common knowledge. Flame cutting is no problem although I have not tried very thick stuff.

Dean

Oxy/Lpg is excellent for cutting, if you have an oxy acetylene set all that is required is a different cutting tip, depending on the size tip quite thick steel can be cut from memory about 100mm (4") maybe more. There is insufficient heat from it for steel welding but brazes very well.
Kryn

Originally Posted by Ueee

I will have the need soon to braze things from thin sheet, bar around 3/4" dia and rebuilding some gear teeth on gears up to 1 1/2" wide. Do you think the bullfinch will manage?

I once had to braze up a casting and the MAPP torch I had did not have enough omph to heat up the whole thing so I got out a gas ring formally used for camping and sat the part on that. With the burner providing 'background heat' and the MAPP torch doing the localised heating I got the job done. You may have to do something similar for your gears (uniform heat is probably better for them any way).

Michael

Does anyone know if you can obtain these any cheaper elsewhere, looks like they would be a cheaper alternative for smaller jobs.

https://www.machineryhouse.com.au/o017

https://www.machineryhouse.com.au/O0181

https://www.machineryhouse.com.au/O0182

Oxygen still seems a little pricey though.

Originally Posted by Michael G

I once had to braze up a casting and the MAPP torch I had did not have enough omph to heat up the whole thing so I got out a gas ring formally used for camping and sat the part on that. With the burner providing 'background heat' and the MAPP torch doing the localised heating I got the job done. You may have to do something similar for your gears (uniform heat is probably better for them any way).

Michael

I do something similar with the Bullfinch Michael to push the envelope a bit. But it is fiddly and slow.

The "colt" solution sounds like it would be OK for Ewan, and obviously has a lot more heat with the 02 cylinder.

If you want to do more than tooling and small jobs, a "colt" type solution sounds good.

I remember now that it was the lack of steel welding ability that the old poster was on about with the Colt, but that would only be an issue if you were doing jobs like exhaust systems.

Interesting subject.

Cheers

Rob

Hi.Guys.
i believe the reason you can't weld with O2 and propane is you have more O2 in the mix and you get an oxidising flame.
kim

Originally Posted by KBs PensNmore

Oxy/Lpg is excellent for cutting, if you have an oxy acetylene set all that is required is a different cutting tip, depending on the size tip quite thick steel can be cut from memory about 100mm (4") maybe more. There is insufficient heat from it for steel welding but brazes very well.
Kryn

The heating tips are different too in my set which was bought complete, from CIG (BOC).

Dean

Originally Posted by BigStick

Hi.Guys.
i believe the reason you can't weld with O2 and propane is you have more O2 in the mix and you get an oxidising flame.
kim

My understanding was that it was due to the temperature that each gas is capable of producing. Acetylene is used because it produces the hottest flame from a flamable gas that can be handled in a safe manner. It is not compressed in the cylinder but disolved under pressure in a solvent such as acetone. There is also an inert packing material in the cylinder. You could well be correct tho. It is a long time since I taught myself to use it.

Max Acetylene temp with oxy, 3160 deg.
Max Propane temp with oxy, 2810 deg.

Figures vary somewhat according to the source.

Ueee.

Some more info would be great Dean.

Kryn has mostly covered what I can tell you. One other thing to consider is that it is not very easy to find the right flame with propane. You will not get the hardening inner flame that you do with acetylene. It is more of an experienced guess from my experience.

Anything else you want to know just ask and I will answer if I can, or maybe someone else will.

Dean

Thanks Dean and Kryn,
My set is a cig Comet 3, at a quick look this can be used with either acet or lpg, i'll have to have a look at the book to see if i need a new reg and tips. Next time i'm in Fyshwick i'll drop in to BOC and ask them maybe.

Cheers,
Ew

Hi Guys.
steel melts at under 1600dec C.
I can't see why you can't melt steel with a flame at 2900 C Why do you need 3100C?
Kim

Originally Posted by Auskart

Does anyone know if you can obtain these any cheaper elsewhere, looks like they would be a cheaper alternative for smaller jobs.

https://www.machineryhouse.com.au/o017

https://www.machineryhouse.com.au/O0181

https://www.machineryhouse.com.au/O0182

Oxygen still seems a little pricey though.

I went to Bunnings the other night...they sell MAP-PRO in a "trade" pack, 4 cylinders for $59. Search - Our range | Bunnings Warehouse
That works out to $15 each. Thats the cheapest so far.

Originally Posted by BigStick

Hi Guys.
steel melts at under 1600dec C.
I can't see why you can't melt steel with a flame at 2900 C Why do you need 3100C?
Kim

I guess there is some truth in the oxidising flame issue. I have tried it on a car panel under the bonnet. Come to think of it the problem was not in melting the wire but the weld looked like the worst weld from hell. I doubt it had any strength in it.

You can cut steel with oxy / lpg easily so its more than melting.

Ueee. Good idea to ask BOC. They should know all the specifics. My kit came with a specific propane regulator which is orange, as is the hose, in keeping with the orange colour of most propane BBQ hoses etc. I don't know if there is any difference with the reg except for the cylinder attachment thread. I actually bought an oxy / acet kit from gasweld with the intention of using it for lpg but returned it when I could not find the adaptor for the cylinder and bought the kit I have from BOC. Gasweld (that store may not have been a Gasweld Dealer then) did not carry the lpg kits at the time.

It was a long time ago and I don't remember the details so check with BOC.

Dean

Originally Posted by BigStick

Steel melts at under 1600dec C.
I can't see why you can't melt steel with a flame at 2900 C Why do you need 3100C?

True, but you also have to heat up the steel faster than the heat can transfer away through the surrounding material. For conductive heat transfer, the energy transferred is proportional to the temperature difference, so the hotter the flame, the faster the metal heats up and the less time the heat has to flow elsewhere.

A good example of this is being able to burn steel wool. Because of the thinness of the stuff the heat can't easily transfer away so a lighter flame is enough to raise the temperature to one where the wool will oxidise (burn) readily. If you tried it with say even a 0.5mm thick piece of sheet it would not work as the heat escapes too easily.

Michael

From memory (going back about 30 years) the acetylene gauge should screw straight into a POL fitting as all fuel gas has a left hand thread, on the system we had was an elbow to bring the regulator to an upright position, as we also had to use it as oxy acetylene for metal welding.
Kryn