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Oxy-hydrogen torch

Posted: Mon May 11, 2009 4:02 am
by inonickname
Well as you may know, you can do cool things with oxyhydrogen torches. Like melting glass, rock and stainless. Cutting cans in half with an invisible flame..

So let say I have a desire to make one, but I have a few questions.

Should I use carbon for the electrodes (I'll probably use a 12v dc source, car battery). There has been discussion about stainless letting chromium into the water, and iron just goes to nothing too fast.

Also, the electrolyte. Salt makes chlorine, so that's out. Is baking soda a good substitute for potassium hydroxide or sodium hydroxide until I can get them? I know it will rape my electrodes.

And the torch. Oxy-hydrogen will be made mixed so I'll have a bubbler at the source and a check valve on the actual torch. Is this enough? Or should I put a flashback arrestor on the torch as well? Will probably just use a needle valve at the torch to control flow. Probably just a slightly crimped bike needle for the tip. As I plan to use mainly metals in the torch, should I be concerned about hydrogen embrittlement?

Thanks guys

Posted: Mon May 11, 2009 5:51 am
by psycix
I have done some experiments with electrolysis. This is my experience:

Electrodes:
-Carbon sucks ass. It breaks down and black dust gets in the water.
-Iron sucks too. It will react, preventing the reactions you do want to happen.
-Stainless steel should be okay. Chromium in the water? I think you will be fine as long as you dont drink it.

Electrolyte:
-Salt. Big nono. (but you knew that)
-Baking soda. Didnt try it.
-NaOH. Works fine. Note that warm water can absorb more.
To get NaOH, simply use drain unclogger.

Torch:
No experience with this. I am afraid that your flame will pop back to the bubbler. If you really want a flame at the torch, you should separate the gases.
To get a constant flame, you will need a big electrolysis cell though.

Posted: Mon May 11, 2009 6:01 am
by Technician1002
psycix wrote: To get a constant flame, you will need a big electrolysis cell though.
The overall electrical to chemical to flame is a net loss as some energy is lost in the cell. The heat in the flame will be lower power than the energy consumed by the cell to create the gas. Concentrating the power to a small point is the advantage of the torch, but an arc welder of the same power is more efficient. :) With the cell, you can save some gas, but storing a lot of mixed gas is called a bomb and can not be recommended here. Wear eye protection. A blown cell with the electrolyte sprayed everywhere is a chemical hazard as well as an explosion hazard. It is best to keep the amount of explosive gas to a minimum.