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Building H20 electrolysis cell, need advice

  1. Feb 16, 2012 #1
    I don't happen to have any welding equipment available to me, so I have decided to make an oxyhydrogen welding torch. That basically involves splitting water by electrolysis, running it through a tube with a blowback arrestor and burning it on the other end. I have read that the voltage should be 1.5-2 volts, and I expect to be running something like 50-150 amps. I'll be using a variac to control the voltage from the wall, then running it through a step-down transformer and finally through a heavy duty rectifier to make it DC.

    The electrolysis cell will use stainless steel electrodes, probably thin sheets of alternating positive and negative voltages. The whole setup will be under low pressure, not more than 2-3 psi at most, and the temperature will be below boiling.

    Having done some research, I am aware that I will need to add an electrolyte to the water to make it conductive enough. However, I would like the water to still be "safe", i.e. not dangerous to the human body in case it should spill or something. I know I can't use table salt since it would emit chlorine gas.

    Are there any safe electrolytes I can use? If not, then what is the safest relatively speaking?

    By the way, if I have overlooked anything else, or if you have any advice, please let me know. I want to do this in a safe way. Thanks!
  2. jcsd
  3. Feb 16, 2012 #2


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    Why would spilled water with table salt emit chlorine gas? Does it build up in the water during electrolysis?
  4. Feb 16, 2012 #3
    I meant chlorine gas produced during operation coming out with the hydrogen and oxygen in the torch flame.

    Am I wrong? I was under the impression that it was dangerous to use table salt, but if not then I'll be a happy camper. Does anyone know how much salt I can mix in before a significant amount of chlorine gas is produced?
  5. Feb 16, 2012 #4


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    Ah ok that makes more sense. The way you worded it I thought you only meant make it safe in case the water spilled out or something. My knowledge on electrolysis isn't very good, so I really don't know if it would emit chlorine gas or not.
  6. Feb 16, 2012 #5


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    Strong bases (NaOH, KOH) and sulfuric acid are the best I can think of. There will be no other electrolysis products but oxygen/hydrogen, and their solutions have relatively low resistance thanks to the presence of either H+ or OH- (so you need lower voltage and they heat less). Are they dangerous after a spill? Yes and no, you don't need them highly concentrated, so if treated with a reasonable attention they are not more dangerous than power tools in the workshop.

    But I have a gut feeling we are reinventing the wheel here.
  7. Feb 16, 2012 #6
    My friend told me I should use Sodium Carbonate (Na2CO3).

    Is there anything else I have forgotten here or am I pretty well covered?
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