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Thread: acetylene bottles lying on their side?

  1. #21
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    People hear about this and gasp, "it will explode". It's been there over 50 years and hasn't yet, I have been taking care of it for the last 27 years without any problems.
    It won't detonate as long as there are no spaces larger than the minimum explosion cell size for the gas and the pressure it is at. Acetelyene isn't the only gas with this characteristic but it is the most familiar. Each gas has a different typical cell size for a given pressure and if it is enclosed in a smaller diameter tube it cannot propagate a detonation wave. It requires that the molecules have a given number within a particular distance from each other and distance from a solid material for detonation to occur.
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  2. #22
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    Evan, would free Acetylene in a metal line be adversely affected by shock such as a sharp blow to the line?

  3. #23
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    Quote Originally Posted by macona
    Well, you got a little right.

    Acetylene cylinders are not filled with cement. It looks like cement but much more porous.
    He actually got most of it right

    Acetylene cylinders are filled with Agamassan, for which Nils DalÚn won the Nobel prize (and ironically was later blinded by an acetylene explosion).
    Agamassan was, until recently, a mixture of asbestos, cement, coal and diatomaceous earth. They replaced the asbestos with some other filler during the asbestos lawsuits of the 80's.

    By the way, the poor guy just asked how long you have to leave acetylene bottles to sit upright before you use them. Do we have to turn everything into a Google flame fest?
    Last edited by lazlo; 12-14-2010 at 05:30 PM.
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  4. #24
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    OK. So far there have been a whole lot of posts none of which has answered the basic question. Say I lie an acetylene cylinder on its side for 24 hours. Then I stand it up, and at 23 hours I start using it. What risk am I running?
    For that matter, what happens if I start using it at 5 minutes?

    I already know you have to let them stand and re-equilibrate. What I don't understand is WHY.

    FYI I have been using oxy/acetylene equipment since I was 15 and I'm nearly 60. And I used to make my living as a shipfitter, whose main tool is a torch.

    metalmagpie

  5. #25
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    Quote Originally Posted by metalmagpie
    I already know you have to let them stand and re-equilibrate. What I don't understand is WHY.
    As has been said, acetylene is unstable above 15 psi, especially in the presence of oxygen. Acetylene dissolves in acetone, and oxygen doesn't, so an acetylene bottle is filled with porous cement, which is then soaked with acetone, and then filled with acetylene.

    At that point, the dissolved acetylene/acetone solution is no longer in contact with oxygen, and the bottle is stable.

    If you tip the bottle on it's side, the acetone and acetylene separate, and you're back to volatile, pure acetylene.

    That's also why you're not supposed to drain an acetylene bottle -- you're likely to backpressure air (oxygen) into the bottle by draining it.

    By the way, this is an acetylene safety brochure that was handed out in one of my welding classes:

    http://www.airproducts.com/nr/rdonly...fetygram13.pdf
    Last edited by lazlo; 12-14-2010 at 06:52 PM.
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  6. #26
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    Something a little funny there. Why should the acetone and acetylene separate when the bottle is on its side? The acetone absorbs the acetylene, presumably it remains a liquid, and is under the effect of gravity. With the tank upright, the liquid is in the bottom- if the tank is on its side, the only thing that's changed is that the bottom is now wider and not as tall. I can't see that as a recipe for the two parts to separate-

    What I can see is the liquid mixture invading the valve. You'd want to let that clear away back into the tank so you don't vent the acetone, hence have the tank upright. I'd bet there's a time period that it takes for a fully invaded valve to clear, and any time longer than that is wasted time if you're waiting to use the tank.

    That's my guess anyway. Other than that, possibly there's an orientation to the foam inside that makes it more workable with the tank upright- though I think that's stretching it.

    I'm reminded yet again about the oxygen bottle falling over in a shop here in town. The valve broke off somehow and the bottle went around the shop, then across the street, where it went through the wall of a tire store. The front and side of that store were almost completely glass- from about two feet above ground and up to near ceiling height. Needles to say, there was a lot of broken glass, but no fire and nobody got hurt apparently.

  7. #27
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    Quote Originally Posted by gary350
    Next I slowly open the valve to blow out any dirt and dust before I attach the regulator.
    I was under the impression that an acetylene cylinder is the only one you shouldn't do this on?

  8. #28
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    Quote Originally Posted by Robert
    At that point, the dissolved acetylene/acetone solution is no longer in contact with oxygen, and the bottle is stable.

    If you tip the bottle on it's side, the acetone and acetylene separate, and you're back to volatile, pure acetylene.

    That's also why you're not supposed to drain an acetylene bottle -- you're likely to backpressure air (oxygen) into the bottle by draining it.
    It has nothing to do with oxygen. There isn't any oxygen in the acetylene bottle and the explosive properties don't depend on oxygen at all. There is free acetylene in the top of the bottle when the bottle is upright. There has to be room for the acetylene to bubble out of solution from the acetone without it passing out of the bottle. The free space isn't empty, it is filled with the porous filler. When the bottle is laid on it's side the free acetylene gradually percolates through the filler away from the outlet leaving the outlet filled with acetone. When the bottle is stood up the acetone gradually percolates down and the free acetylene percolates back to the top.

    There is also a fine powder residue that is a result of particles shed by the filler material during normal handling. That powder must have time to settle back into the filler matrix along with the acetone. This in fact can be the greatest source of problems because if traces of the powder are carried out with acetone they can destroy the regulator.

    This is not a guess or my opinion. My wife sells industrial gases and I am trained on the properties and handling of industrial gas cylinders so I can fill in for her if necessary.


    Quote Originally Posted by Radkins
    Evan, would free Acetylene in a metal line be adversely affected by shock such as a sharp blow to the line?
    Not likely. The rest of the line is still below the propagation cell size.

    BTW, to answer how long the bottle must be stood up before using: One hour for every hour down to a maximum of 24 hours. If it has been down for more than 24 hours then it should be stood up for 48 hours.
    Last edited by Evan; 12-14-2010 at 09:12 PM.
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  9. #29
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    Quote Originally Posted by Evan
    This is not a guess or my opinion. My wife sells industrial gases and I am trained on the properties and handling of industrial gas cylinders so I can fill in for her if necessary.
    My Wife is the North American OSHA acetylene safety regulator, so I'm trained for hazmat handling of acetylene bottles



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  10. #30
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    The first poster is total bunk.

    The second poster is only partly bunk. The filler has nothing to do with "allowing the acetylene to dissolve in the acetone". It will do that without filler. It is to make sure that no part of the tank has an open area that exceeds the minimum detonation cell size.

    More bunk: Acetylene doesn't become unstable in contact with oxygen.

    Even more bunk: Acetone can't "clog a regulator". It is a volatile liquid. It's the powder carried with it than can damage the regulator.

    BTW, the acetone doesn't "stabilize" the acetylene. By dissolving the acetylene in the acetone it is no longer under pressure as a compressed gas. It is in a solution in a liquid that it essentially incompressible. The only portion of the acetylene that is a compressed gas is the small amount of free acetylene at the top.
    Last edited by Evan; 12-14-2010 at 09:29 PM.
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