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  • BigMike782
    replied
    I have never understood trying to tell if a cylinder is full by opening the valve. The correct nipple, coupling and gauge is not that hard to get.
    At 70 degrees an acetylene cylinder is considered full at 225 psi.

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  • Ridgerunner
    replied
    The old school way to test if any tanks were not empty was to put your thumb over the opening on the tank and quickly open and close the valve. It was said that if held tightly it would take over 250 psi to blow your thumb off the opening.
    Some places require check valves and flash back or spark arrestors at the gauges. Even if they are not required it is good practice to have them on.

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  • Sparky_NY
    replied
    Acetylene is well known to be unstable. The method described was a very poor idea, I have wondered many times if a acetylene tank was empty or how much it had in it, its a simple matter to just screw a regulator on and open the tank, the gauge gives a accurate true reading. Cracking the valve open yielded no meaningful information on the tanks fill. 300 psi is full and I have found once it gets below 50 psi it may not work well, especially in cold conditions and if a larger tip is used which needs more flow. I suspect that is because the acetylene is dissolved in the tank and does not vaporize well when nearing empty.

    The fact that acetylene is dissolved in acetone in the tank along with a fibrous filler of some sort attests to its instability and pretty well answers your original question. Its unstable in any volume.

    Lot of horror stories about use of acetylene out there but many come down to poor practices. Lets face it, oxy/acetylene has been used forever and considering the numbers in use problems are very rare if used properly. Not used properly, it is very unforgiving !

    In the case cited, there is no doubt that a certain volume will mix with air to form a perfect ratio to detonate with the slightest ignition source. In this case it could have been as simple as a static electricity spark. Also, the standard limit of keeping the pressure under use to 15psi or lower was ignored, the flow out of the tank was at tank pressure into the room. Does flow from the tank at over 15psi create a unstable situation? I don't know but was never tempted to find out, I have too much respect for the stuff.
    Last edited by Sparky_NY; 04-13-2021, 07:27 AM.

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  • Bob La Londe
    replied
    I guess some research is in order. I was told a certain volume of acetylene can become unstable. I have seen a spontaneous ignition of acetylene in open air. A gas bottle valve was cracked to show the tank was not empty, and somebody stuck their hand in front of it to feel the flow. It detonated. I ran to get a welding glove and turned off the valve which was still spewing flame.

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  • ironmonger
    replied
    Originally posted by Ohio Mike View Post
    Ok, Oxygen is CGA 540 thread. ****Let me be very very clear, regulators are NOT interchangeable!**** They are this way for very good reason... I will quote Lincoln: "For instance, if a used acetylene regulator were allowed to be assembled to a full oxygen cylinder, the result would be a catastrophic fire/explosion with the possibility of severe injuries and/or death to personnel in close proximity."

    https://www.harrisproductsgroup.com/...ead-types.aspx
    https://www.cganet.com/home-oxygen-safety/
    In my past life as a medical gas instruction/installer I had occasion to rebuild some Airco 2 stage regulators. I got parts from SealSeat in California. I don't know if they still sell retail, but they did. The internal parts are identical for all the gases... insofar as they all have the same part numbers. Same nylon high pressure seats and the 'rubber diaphragm are the same. Different springs for low pressure fuels and high pressure gases. This not to say that the OP's statement about mixing oxygen and fuel gas would not be dangerous.. it certainly would. Only referring to the gas compatibility with internal bits of the regulator.

    As far as the danger of 15psi for acetylene, the gas is in the regulator is at full cylinder pressure (some 200 psi or so) without being dissolved in acetone. I love a mystery :>) I wonder if the 15psi bit came from the early times of compressed gases, perhaps contamination of the gas led to instability issues.

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  • QSIMDO
    replied
    Originally posted by BigMike782 View Post
    510 is left hand, 300 is right hand.
    hardly will 300 be outlawed.
    Brain fade.

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  • BigMike782
    replied
    Originally posted by QSIMDO View Post

    Acetylene is left hand thread.
    If that adapter is to go from right to left or vice versa it should be outlawed immediately!
    510 is left hand, 300 is right hand.
    hardly will 300 be outlawed.

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  • QSIMDO
    replied
    Originally posted by dian View Post
    thanks, my suspicion was correct, the threads are different in the u.s.:

    https://www.ebay.de/itm/Gewindeadapt...-/132651163933

    i better ask this somwhere else, unless a european member chimes in.
    Acetylene is left hand thread.
    If that adapter is to go from right to left or vice versa it should be outlawed immediately!

    Leave a comment:


  • dian
    replied
    thanks. i bookmarked it, so i might be smarter next time. although you cant be really be smart when dealing with cn.

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  • MattiJ
    replied
    https://www.tedpella.com/company_htm...onnections.htm

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  • MattiJ
    replied
    Originally posted by dian View Post
    thanks, my suspicion was correct, the threads are different in the u.s.:

    https://www.ebay.de/itm/Gewindeadapt...-/132651163933

    i better ask this somwhere else, unless a european member chimes in.
    Gas Bottle Threads vary even here in Europe. Finland seem to use different threads compared to germany for example. You probably have choice of German and French standards..

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  • BigMike782
    replied
    Also know that propane and acetylene share the same CGA connection, 510 but an LP regulator should NEVER be used on acetylene because LP is safe over 15psi, acetylene is not.

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  • Ohio Mike
    replied
    Threads aside what I was trying to convey is that any regulator used for oxygen must be designed specifically for oxygen or very bad things can happen. Just be careful.

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  • dian
    replied
    thanks, my suspicion was correct, the threads are different in the u.s.:

    https://www.ebay.de/itm/Gewindeadapt...-/132651163933

    i better ask this somwhere else, unless a european member chimes in.

    Leave a comment:


  • Ohio Mike
    replied
    Ok, Oxygen is CGA 540 thread. ****Let me be very very clear, regulators are NOT interchangeable!**** They are this way for very good reason... I will quote Lincoln: "For instance, if a used acetylene regulator were allowed to be assembled to a full oxygen cylinder, the result would be a catastrophic fire/explosion with the possibility of severe injuries and/or death to personnel in close proximity."

    https://www.harrisproductsgroup.com/...ead-types.aspx
    https://www.cganet.com/home-oxygen-safety/

    Leave a comment:

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