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Reinforcing Copper Pneumatic?

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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Unread postAuthor: DYI » Fri Feb 08, 2008 10:59 pm

Although many pressure pipes have a safety factor of 3, the safety factor on copper tubing is actually in the 5-8 range. Hard copper tubing of any strength other than DWV in sizes under 2" will generally have a burst pressure of over 3 000 psi, and the malleability of copper makes it less prone to shrapneling like PVC does.

I've never used copper on anything high pressure because threaded steel is cheaper, more available, easier to connect, and has a higher temperature range which is important when using steam, but joined properly with copper pressure fittings, you can do 1000 psi in all sizes under 2" and still have a very reasonable safety margin.
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Unread postAuthor: peeeto » Sat Feb 09, 2008 1:05 am

paaiyan wrote:Any particular reason you were putting *'s..?

dunno - that's the way i've seen it done on other sites - don't know why, just never really seen the big box stores mentioned by name, as if they were eveil - i just thought it was some netiquitte thingy or sumpthin.
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Re: Reinforcing Copper Pneumatic?

Unread postAuthor: Ragnarok » Sat Feb 09, 2008 12:48 pm

KamranGo wrote:Or is this really a pretty irrational fear to have? I'm not familiar at all with working with the material, so I don't know if it requires any special tools or if it is much more difficult to work with than PVC.

It's fairly irrational. As you said, copper is malleable - and that's actually a good thing. It means that unlike PVC, copper will always tear rather than shatter - and almost regardless of temperature. PVC becomes very brittle below freezing. Copper is still just as malleable, and thus just as impossible to shatter... even after being cooled with liquid nitrogen.

And per unit mass, copper is about two times tougher (absorbs more energy in fracture) than steel - at room temperature, when it gets colder, copper gets relatively better - because of it's vast malleability.

And bearing in mind people will use copper launchers at 300 to maybe 500 psi, with exceptionally few failures, they're not exactly risk prone. If you're still in three figures of pressure, and still in small sizes (i.e. cheap sizes), I'd bet on it still being capable of holding said pressure.

If you're really still worried about the problem, just put an ABS pipe around the chamber to sheathe it and protect it from knocks.

@peeeto: Sounds like you're talking about the dreaded "Scottish Play".
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