Hydrogen Torches

Discussion in 'The Projects Forum' started by jpanhalt, Aug 1, 2008.

  1. jpanhalt

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    Jan 18, 2008
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    My experience with hydrogen/oxy torches goes back a few decades, but the chemistry hasn't changed in that time. I used them for "glassblowing" fused quartz, which was needed for our work down to 200nm in the UV.

    In short, I think it would be absolutely foolish to pre-mix oxygen and hydrogen in any sort of volume and feed that mixture to a torch. We mixed the hydrogen and oxygen before the tip, much like a conventional welding torch, and had flash back arrestors on the H2 line. You still have to be careful, because the combustible limits for H2 are so wide.

    John
     
  2. thingmaker3

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    Can you say more about those flashback arrestors? I've read the arrestors used of acetylene are not sufficient for hydrogen, due to H2's higher flame velocity...
     
  3. jpanhalt

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    That may very well be true about the flame propagation speed. The device we used was just from a standard welding setup, as I recall. It was 40 years ago, and one tends to lack a full appreciation of the dangers when in his 20s. Maybe I was just lucky.

    However, if the tank had contained a 2:1 mixture of hydrogen to oxygen (Brown's gas), I don't think I would have given it a try even then.

    BTW, I was taught to turn the oxygen off first and still do when using oxy-acetylene. (I reduce both until there is barely a flame and then kill the oxygen first. I don't like the think smoke from acetylene, but it is how I was taught to do it.) That sequence avoids the "pop", which is presumably a small flashback. However, I just searched the web and found several statements encouraging one to turn the fuel gas off first.

    Here is a quote from the Ohio State University Ag Services:
    In contrast, a welding site is still recommending turning off the fuel gas first. If I were going to be using a oxy-hydrogen torch today, I would definitely read up more on the correct order to shut down the gases.

    John
     
  4. thingmaker3

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    Thank you John. I was taught similarly to the Ohio Ag instructions.

    I just wish I could find some reliable present day info on hydrogen torches. My searches keep getting bogged down with the automotive references.:( I want to try one of the hydrogen torches, but I want even more to remain in good health!:eek:

    I'll have to keep wading through the free-energy crowd's obstacles, I guess.:rolleyes:
     
  5. Wendy

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    Actually I'd be interested in the welding applications myself. Small volume isn't expensive, it would be easier than keeping tanks around.
     
  6. jpanhalt

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    @thingmaker3

    I searched more on the question of which order to turn the gases off after posting. For oxy-hydrogen, it was hopeless as you mention because of all the HHO stuff. For oxy-acetylene, it seems the equipment manufacturers recommend turning the oxygen off first, which makes as more sense to me.

    By that I mean, you flush lines first and have acetylene in the torch body (not oxygen) before lighting, right. Just prior to shut down, the torch body has oxy-acetylene mix. By turning the oxy off first, the body then has only acetylene in it, which is mixing with air at the tip. I don't see how turning the acetylene off when the flame is with air at the tip only could be any more dangerous than turning the acetylene off when some of the torch body is full of oxy-acetylene.

    The OSU comment about the "pop" being essentially a good sign just didn't make sense. The pop is flashback, which one is trying to prevent.

    I certainly don't want to start any argument here on the proper order, but I will stick with the manufacturers who have a bigger incentive than OSU to get it right. John
     
  7. linchiek

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    Jul 23, 2008
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    gee.... thnx for da reminder...... :)
     
  8. linchiek

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    if the HHO generator doesn't really work as claim, i'm going to make myself a HHO torch...! hehe! :D
     
  9. thingmaker3

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  10. jpanhalt

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    Did you hear the pop when he turned the torch off? I use a Smiths Little Torch (about $100) and really like it for hard solder, brazing, and light welding. I will continue to keep my gases separate.

    Clearly, there are things where oxy-acetylene is second choice to hydrogen, but separate tanks are pretty cheap compared to the risks of making your own mixed fuel. Of course, there is no thrill factor in buying the pure gases.

    For real precision, I prefer TIG. With a foot operated system, you have almost instantaneous control of heat. I have welded a 0.016 aluminum battery box using TIG. A good welder can do that with gas, but not me.

    Thanks for moving this to its own thread. Perhaps the discussion will be a little less volatile than one involving "HHO."

    John
     
  11. linchiek

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    what type of flashback arrestor suitable to be used with h2 o2 torch? :confused:

    [​IMG]

    can use this type? ppl from hhoforum recommend using bubbler... :)
     
  12. thingmaker3

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  13. linchiek

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  14. AlexR

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    It all depends on what caused the explosion, was it flashback from the engine or was the ignition source inside the H/O generator itself. Given that the gas in the box is in the the perfect H2/O2 ratio for 100% efficient combustion/explosion, any spark inside the box caused by a loose connection or even static electricity will send the whole kit sky high.
     
  15. ritajones

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  16. thingmaker3

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    New? Around $400 US. Plus tanks and hoses, if one does not already have them. I've not had much luck finding them used.
     
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