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Is my air cannon safe?

  1. Nov 13, 2011 #1
    I left my Air cannon outside during the winter. I was wondering if it is still safe to use or if the cold might have left it unsafe.

    The air tank is made of 2 PVC caps attatched to a PVC T pipe, in between there is ABC pipe spacers... The center of the T pipe is connected to a valve, which is connected to the shooting barrel at the other end..with standard PVC cement glue just so you get the picture.

    So yeh was just wondering if it is still safe to use it. I used to put it at 120 PSI on average, and had the balls to use it up to 180PSI. It's a beast. But was just wondering if it is safe to use anymore, now that i left it in the winter.
     
  2. jcsd
  3. Nov 13, 2011 #2

    DaveC426913

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    Gold Member

    Well no one here is about to advise you that it's safe. We can't. Liability issues.
    Especially a homemade device.

    Same reason we can't advise you on whether a pain in your abdomen is nothing to worry about.
     
  4. Nov 13, 2011 #3
    let me ask more specifi question. does cold shrimk pvc pipe or sbc pipes, or are they weathered resistant.
     
  5. Nov 13, 2011 #4
    UV light can attack PVC.
     
  6. Nov 14, 2011 #5
    If you made it yourself how did you test it for safety first time round?
     
  7. Nov 14, 2011 #6
    PVC is not rated for air pressure, so no, it isn't safe (I don't know enough about PVC to tell you if it's worse now than before, though). This is an extremely common mistake among air-cannon makers.

    The reason is that PVC's failure mode when holding air is to blow up, sending shrapnel and a hearing-loss-inducing pressure wave outwards. Plus, the shock of firing the cannon makes failure much more likely.

    If you are concerned about safety, I'd recommend a switch to ABS (which is somewhat more expensive, but should still be within your budget).
     
  8. Nov 14, 2011 #7

    Bandit127

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    Gold Member

    Most polymers degrade in UV light. I think your PVC will probably loose more strength over Summer of it is left outside. (Unless it had water in it over Winter that turned to ice and expanded).

    ABS is standard for polymer piping for compressed air but it still degrades over time. 10 year old ABS piping gets leaky.

    If you are in doubt, I would rebuild it.

    If you are hell bent on reusing it, pressure test it with water. That way failure under full pressure will be less likely to lead to injury.
     
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