Acetelyne explosion?
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  1. #1
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    Acetelyne explosion?

    how dangerous is it if someone runs too much pressure? I noticed a coworker whose cutting outfit had a broken acetelyne pressure guage on his regulator today. I fixed it, but was wondering if anyone knows definitively from experience what can happen, and how much is too much?

  2. #2
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    Re: Acetelyne explosion?

    I don't know, but I about wet my pants the other other day at work. I opened the valve on the acetylene tank and the needle shot WAAAYYYYY up into the red. Something like 25-30psi.

    It mae me wonder wht the dang regulators even allow goofy stuff like that. Why aren't they limited to 14psi?
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    Re: Acetelyne explosion?

    yea what the hell I always wondered that to.... its dangerous to go about 15psi, but my dang gauge is adjustable to 50psi!?

    I have no idea what happens above 15 psi either, all my book says is "it becomes unstable"
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  4. #4
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    Re: Acetelyne explosion?

    http://www.nbc5i.com/news/13751997/d...l?dl=mainclick


    Just follow the rules; they are there for a reason.

  5. #5
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    Re: Acetelyne explosion?

    TEK- thanks for the link... I still am curious though. The guage that I fixed today may have been broken for a long time. Is it just dumb luck that this guy never got hurt? I would really like to know what specifically can happen. I was always one of those kids who asked too many questions!

  6. #6
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    Re: Acetelyne explosion?

    You probably won't find anybody living that has experience using acetylene at pressures above 15 psi. Yes it really can explode if you try to light it at high pressures.

  7. #7
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    Re: Acetelyne explosion?

    The acetone that stabilizes the Acy doesn't stay in the tank. It will start to flow out with the gas.

    I haven't witnessed the results of that, but it is what you need to avoid.

  8. #8
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    Re: Acetelyne explosion?

    Quote Originally Posted by AnotherDano
    The acetone that stabilizes the Acy doesn't stay in the tank. It will start to flow out with the gas.

    I haven't witnessed the results of that, but it is what you need to avoid.
    Aspiration of the acetone occurs when you remove acetylene from the tank faster than the tank can handle.

    When you exceed 15 psi of acetylene gas the gas can detonate. I have seen it happen once, the hose was laid wide open and left burning in places, we were lucky that it oxygen hose was not perforated at the same time or we would have had a very large blow torch in a very small compartment. Someone close to the acetylene tank secured the tank really fast. The dentonation can set off the tank. It didn't our case, we were just lucky. Other than the hose, the only causulty was several pair of undershorts!!!
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  9. #9
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    Re: Acetelyne explosion?

    I just posted a new thread on acetylene, that might answer some of your questions. John G.
    SMAW,GMAW,FCAW,GTAW,SAW,PAC/PAW/OFC
    and Shielding Gases. There all here.


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  10. #10
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    Re: Acetelyne explosion?

    Just a note regarding the comment about "I opened the cylinder valve and the needle shot to over 15 psi". I have always made a practice upon shutdown to depressurize/bleed and then back the regulator out until it moves freely thus avoiding the surge on start up. I routinely check the regulator prior to opening the cylinder valve as well.

  11. #11
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    Re: Acetelyne explosion?

    Quote Originally Posted by wielro
    Just a note regarding the comment about "I opened the cylinder valve and the needle shot to over 15 psi". I have always made a practice upon shutdown to depressurize/bleed and then back the regulator out until it moves freely thus avoiding the surge on start up. I routinely check the regulator prior to opening the cylinder valve as well.

    That is a very true statement and everyone should do that out of habbit, if you want to be safe. John
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  12. #12
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    Re: Acetelyne explosion?

    Quote Originally Posted by wielro
    Just a note regarding the comment about "I opened the cylinder valve and the needle shot to over 15 psi". I have always made a practice upon shutdown to depressurize/bleed and then back the regulator out until it moves freely thus avoiding the surge on start up. I routinely check the regulator prior to opening the cylinder valve as well.
    What they said!! And keep acetylene bottles upright. Never, ever let the valve be damaged.
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  13. #13
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    Re: Acetelyne explosion?

    Quote Originally Posted by daddy
    how dangerous is it if someone runs too much pressure? I noticed a coworker whose cutting outfit had a broken acetelyne pressure guage on his regulator today. I fixed it, but was wondering if anyone knows definitively from experience what can happen, and how much is too much?
    I think that at those pressures, the acetylene hose can detonate. Even with just air, and certainly with oxygen. So when you have fifty or a hundred feet of hose on reel it might be a problem. Ha-ha.

    The best acetylene accident waiting to happen is when it gets cold. If you take a full bottle of acetylene and cool it down to about zero degrees Fahrenheit. Acetylene will not come out.

    If you are with a new apprentice and he gets no gas from a cold bottle, he takes the regulator off the bottle. He is cold and angry and does not like that he had to go out and get another bottle. And he leaves the main valve open assuming there is nothing in the tank. I have seen where nothing comes out of a nearly full tank.

    An hour later the sun comes out and the tank starts to put out acetylene. Or the tank gets put into the indoor storage rack, from the cold van. Ha-ha. The greatest delay release I ever saw.



    Sincerely,


    William McCormick

  14. #14
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    Re: Acetelyne explosion?

    Quote Originally Posted by daddy
    how dangerous is it if someone runs too much pressure? I noticed a coworker whose cutting outfit had a broken acetelyne pressure guage on his regulator today. I fixed it, but was wondering if anyone knows definitively from experience what can happen, and how much is too much?
    I think that at those pressures, the acetylene hose can detonate. Even with just air, and certainly with oxygen. So when you have fifty or a hundred feet of hose on reel it might be a problem. Ha-ha.

    The best acetylene accident waiting to happen is when it gets cold. If you take a full bottle of acetylene and cool it down to about zero degrees Fahrenheit. Acetylene will not come out.

    If you are with a new apprentice and he gets no gas from a cold bottle, he takes the regulator off the bottle. He is cold and angry and does not like that he had to go out and get another bottle. And he leaves the main valve open assuming there is nothing in the tank. I have seen where nothing comes out of a nearly full tank.

    An hour later the sun comes out and the tank starts to put out acetylene. Or the tank gets put into the indoor storage rack, from the cold van. Ha-ha. The greatest delay release I ever saw.



    Sincerely,


    William McCormick

  15. #15
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    Re: Acetelyne explosion?

    Quote Originally Posted by daddy
    how dangerous is it if someone runs too much pressure? I noticed a coworker whose cutting outfit had a broken acetelyne pressure guage on his regulator today. I fixed it, but was wondering if anyone knows definitively from experience what can happen, and how much is too much?
    I think that at those pressures, the acetylene hose can detonate. Even with just air, and certainly with oxygen. So when you have fifty or a hundred feet of hose on reel it might be a problem. Ha-ha.

    The best acetylene accident waiting to happen is when it gets cold. If you take a full bottle of acetylene and cool it down to about zero degrees Fahrenheit. Acetylene will not come out.

    If you are with a new apprentice and he gets no gas from a cold bottle, he takes the regulator off the bottle. He is cold and angry and does not like that he had to go out and get another bottle. And he leaves the main valve open assuming there is nothing in the tank. I have seen where nothing comes out of a nearly full tank.

    An hour later the sun comes out and the tank starts to put out acetylene. Or the tank gets put into the indoor storage rack, from the cold van. Ha-ha. The greatest delay release I ever saw.



    Sincerely,


    William McCormick

  16. #16
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    Re: Acetelyne explosion?

    The best acetylene accident waiting to happen is when it gets cold. If you take a full bottle of acetylene and cool it down to about zero degrees Fahrenheit. Acetylene will not come out.
    That's about the most dangerous piece of info you've put out so far, William. This is absolutely NOT true and should not be posted as such. Thre frezzing point of acetylene is in the extreme sub-zero's. I'm not sure what the freezing point of acetone is,,,,,,,,but I'm darn sure it isn;t zero by a long shot.

    The hotter it is the more unstable acetylene gets and the reverse is true for cold.

  17. #17
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    Re: Acetelyne explosion?

    I agree with Sandy and most of you cold country guys know it too. I have used acety at 14 deg Far. and it worked just fine. Wild Bill is gonna get somebody hurt . Use more caution reading his posts than you do using acetylene.....

  18. #18
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    Re: Acetelyne explosion?

    I was told by a real NERD that the really dangerous point in acetylene outlet pressure is 30 psi. And, that the industry felt that they should state 15 psi is the safe
    MAXIMUM pressure , so many , if not most acetylene regulators are red lined above 15 psi , or some even won't allow more than 15 P. S. I. output. and some of my Victor reg. screws are too short to allow more than 15 psi output . Anyways, unless you want to go meet Satan real soon, just abide by the 15 psi limit , and be safe . If you're cutting really thick metal , use a journey man size single stage regulator and a BIG hose , & stay under 15psi.
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  19. #19
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    Re: Acetelyne explosion?

    I was told by a real NERD that the really dangerous point in acetylene outlet pressure is 30 psi. And, that the industry felt that they should state 15 psi is the safe
    That sounds very realistic. Most guidelines are set within a safe zone. There won't be any magic happens at 16psi. The basics are, once removed from the acetone (as the acetylene in your hose is), acetylene becomes unstable at any pressure. The higher the pressure, the more so, the higher the temperature the more so. The 15psi red rule probably covers a nice range of conditions.

  20. #20
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    Re: Acetelyne explosion?

    Sandy, and TEK... thank you for the responses, esp. with regard to inaccurate / mis-information... I am very new here and sincerely hope that I am not led astray. So far I have found alot of very helpful info, and hope to be able to contribute at some point. " Wild Bill " with a grain of salt. got it.

  21. #21
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    Re: Acetelyne explosion?

    The actual OSHA standard, 1910.253(a)(2) says,

    Maximum pressure. Under no condition shall acetylene be generated, piped
    (except in approved cylinder manifolds) or utilized at a pressure in excess of 15
    psig (103 kPa gauge pressure) or 30 psia (206 kPa absolute).
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  22. #22
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    Re: Acetelyne explosion?

    Boiling point (1.013 bar) : -83.8 °C

    Melting point : -84 °C

    Autoignition temperature : 325 °C
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  23. #23
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    Re: Acetelyne explosion?

    Some more information on acetylene can be found in Jefferson's Welding Encyclopedia/18th Edition, Published by American Welding Society. Edited by Robert (Bob) O'Brien, who was the technical director for AWS after retiring from Linde, where he was the man who patened Plasma. He was a very good friend and respected leader, in the industry. Good information. John G.
    SMAW,GMAW,FCAW,GTAW,SAW,PAC/PAW/OFC
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  24. #24
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    Re: Acetelyne explosion?

    Quote Originally Posted by Sandy
    That's about the most dangerous piece of info you've put out so far, William. This is absolutely NOT true and should not be posted as such. Thre frezzing point of acetylene is in the extreme sub-zero's. I'm not sure what the freezing point of acetone is,,,,,,,,but I'm darn sure it isn;t zero by a long shot.

    The hotter it is the more unstable acetylene gets and the reverse is true for cold.

    No my friend the information you just put out is the most dangerous thing I have seen.

    I have had to change out multiple bottles working in windy allies in the city, changing out condenser units. I had the problem of three full bottles to make two weld joints. The bottles were stored outside. And put into the back of a cold van, and driven to the city.

    I was working with a fellow named John, he was doing the soldering. He could not even heat one joint, there was no pressure in the tank. Immediately in under 60 seconds the torch went dead. I got another tank and hooked it up, it went dead in ten seconds. Then we realized that either we got empty tanks by mistake or it was that cold.

    So we started putting the tanks inside to warm them up. The problem was that it was only about 50 degrees inside the building under construction. The other problem was that one tank, we thought was really empty.

    So we put the possibly full tank and the one we believe is empty, inside to warm. We waited about an hour.
    He still could not heat the pipe with the second and third tank that were both low on pressure. So we put two inside while he stayed out to make it look like we were working with the third.
    About an hour later, I go in and just crack the valve to see which if any of the tanks were thawing. One gave nothing the original one that we felt was empty. The other I could hear.

    So I put the regulator on the tank we had inside that seemed to be somewhat full, and just out of my understanding of refrigeration, and acetylene shut the valve on the other we thought was empty. Even though two experts in acetylene handling that have both over thirty years declared it empty. I had checked it anyway.

    Well we ended up waiting for it to warm up in the city. And then were able to silphos one joint with the one tank after lunch. And to my surprise I go in and put the regulator on the wrong tank the one we declared empty, and I have a gauge reading of one half tank. I put it on the other and had a gauge reading of half a tank of acetylene.

    You have to take into consideration that when the gas is allowed to escape it also has the effect of cooling the tank more. Till nothing comes out by human perception.

    During all this we started to form strange conclusions that we later threw away. The first tank was the warmest, it went the longest and then got the coldest of all the tanks. The other two tanks had gotten cold in the windy alley and put out almost nothing compared to the first. So there is a lot to consider before you just tell someone that acetylene does or does not turn to a gas at a certain temperature. I was there. It was scary even though we violated no rules of using acetylene. It was cold but not that cold.

    This is just some of the stuff that went through our minds. Amongst some of the things that went through our mind was a bad regulator. Something in the torch or hose. Maybe we weren't opening the acetylene main valve enough. Believe me if it could happen we thought of it. We were there and had to perform.

    After the tanks warmed up they were all nearly full.

    We get and use dissolved acetylene, maybe you do not.

    You could easily simulate the cold with dry ice. Or liquid carbon dioxide with a siphon tube for freezing pipes.


    Sincerely,


    William McCormick

  25. #25
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    Re: Acetelyne explosion?

    Quote Originally Posted by daddy
    TEK- thanks for the link... I still am curious though. The guage that I fixed today may have been broken for a long time. Is it just dumb luck that this guy never got hurt? I would really like to know what specifically can happen. I was always one of those kids who asked too many questions!

    Because in the cold the tanks lose pressure. And you have to compensate by decreasing the pressure the regulator diaphragm keeps against the tank pressure. On a hot day it would be way over thirty pounds.

    Sincerely,


    William McCormick
    Last edited by William McCormick Jr; 12-19-2007 at 10:19 PM.

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