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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: octane89 » Sun Oct 28, 2007 11:15 am

If you're in the US I can get you 2 1/2 ft of 4in PVC for $6-7 but you'd have add for shipping. I'd just look around more if I were you.
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Unread postAuthor: SpudBlaster15 » Sun Oct 28, 2007 11:34 am

Since you are not going to be using the launcher at pressures in excess of 60psi, DWV ABS will be fine to use. An advanced combustion launcher, which many have constructed using ABS, will typically generate pressures in excess of 70psi, and I have yet to see an advanced ABS combustion launcher fail when properly built. Yes, the duration of pressure within the chamber is higher when the pipe is used to construct a pneumatic cannon, but this should not have a significant effect when the launcher is used at such a low pressure as 60psi.

Even if the ABS chamber failed, it would not do so in an explosive manner. It would simply rip down the length of the pipe, releasing the pressure with nothing more than a loud bang. PVC tends to fragment upon failure, especially when cooled to 0*C or lower. ABS does not lose its resilience until it is chilled below -25*C. Not to mention the fact that ABS has greater UV resistance, shock resistance, chemical resistance, etc...

Just don't buy cellular core ABS, and you will be fine.
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Unread postAuthor: cwazy1 » Sun Oct 28, 2007 12:10 pm

hmm, i see, but what is non cellular core abs?? the only abs i see around here is cell core. so youre saying that cell core abs for pneumatic is a no-no even if the pressure is only going to be 60 but non cell cure abs is okay?
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Unread postAuthor: HaiThar » Sun Oct 28, 2007 12:28 pm

Never use Cellular core. EVER. IN ANY CANNON. Also, ABS can be bought pressure rated, it's just not common. Maybe you should consider a different C/B ratio? A chamber with a huge diameter doesn't always make it great....Anyway, if it's not cell core, the DWV can probably be taken up to 60-70 psi. I would actually install a pop-off valve, just to make sure you don't accidently go over the limit, but it's probably not neccessary.
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Unread postAuthor: cwazy1 » Sun Oct 28, 2007 12:36 pm

^^ actually, alot of ppl use cell core abs for combustions.
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Unread postAuthor: SpudBlaster15 » Sun Oct 28, 2007 12:39 pm

Although cellular core ABS would probably withstand 60psi, I would not suggest using it, as it is essentially a block of ABS "foam" encased in 2 very thin pieces of pipe.
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Unread postAuthor: noname » Mon Oct 29, 2007 9:45 pm

SpudBlaster15 wrote:Even if the ABS chamber failed, it would not do so in an explosive manner. It would simply rip down the length of the pipe, releasing the pressure with nothing more than a loud bang. PVC tends to fragment upon failure, especially when cooled to 0*C or lower.


I'm not going to get in a [female doggy] fight with you SpudBlaster, I'm just adding a bit to your post. ABS can throw fragments; they just aren't small ones. I intentionally blew up some 3" DWV cell core ABS (300+ psi pressure spike :P ) and the smallest piece I could find was about 4-5" long and about 2" wide. There were 8 or 9 pieces.
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