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GGDT request, please

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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GGDT request, please

Unread postAuthor: bluerussetboy » Sat Jan 05, 2008 7:23 pm

normally i don't play with pneumatics, but i have an overabundance of .451 lead balls that i use with my 1858 Remington cap and ball pistol. i'm thinking i will try my hand at a barrel sealer. actually two, one will be pistol and the other a long rifle(minus rifling).

i run linux so i'm not able to natively run GGDT. i also borked my python so CALM won't run either. i was wondering if someone could run some info through GGDT for me.


pistol:
300 psi
chamber: 12"x1" sch40 PVC (10.39 cu.in)
barrel: 12"x3/8" sch40 PVC (.483" dia.)

rifle:
400 psi
chamber: 48"x1" sch40 PVC (41.56 cu.in)
barrel: 108"x3/8" sch40 PVC (.483" dia.)

projectile:
patched .451 lead ball (.480" dia.)
weight: 8.87745 grams

less than 5 psi of friction

valve will be in a 1" tee and hopefully piloted by a modified blowgun


the 1858 remington shoots around 550-720 ft/s with an 8" barrel, 5-6 ft/lbs of recoil, and 200 ft/lbs of muzzle energy

Thanks
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Last edited by bluerussetboy on Sat Jan 05, 2008 7:29 pm, edited 1 time in total.

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Unread postAuthor: DYI » Sat Jan 05, 2008 7:27 pm

You do realise if that the PVC has a defect and fails, you will be completely forked, right?

Before I give any specs, use metal tubing which is rated for the pressure you're using. I know that 1" PVC is rated for it, but it isn't worth the risk.
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Unread postAuthor: Fnord » Sat Jan 05, 2008 7:30 pm

Pistol
355 fps
35 ft-lbs


Rifle
820 fps
204 ft-lbs

Using 400 psi in pvc is crazy by the way.
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Unread postAuthor: ALIHISGREAT » Sat Jan 05, 2008 7:32 pm

i agree with DYI you should use copper or steel and take it to 500psi+ :twisted:

edit: i wouldn't trust a blowgun past 300psi
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Unread postAuthor: DYI » Sat Jan 05, 2008 7:37 pm

Well, JSR has used pressures like that in small ID PVC. But I wouldn't recommend it at all.
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Unread postAuthor: ALIHISGREAT » Sat Jan 05, 2008 7:40 pm

DYI wrote:Well, JSR has used pressures like that in small ID PVC. But I wouldn't recommend it at all.


JSR must be crazy, in europe (as far as i know) we don't have the sch pipe system so the walls of pipe get thinner as the pipe diameter lowers so the highest pressure rating i can get in the uk for pvc is 16bar.
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Unread postAuthor: SpudFarm » Sat Jan 05, 2008 7:45 pm

if you are going to use 400psi or if i was going to do it the only material i would use is steel! i think 2" steel pipe is rated for 360psi but it can take 400 easily
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Unread postAuthor: DYI » Sat Jan 05, 2008 7:47 pm

2" SCH 40 welded steel actually has a burst pressure of over 2000 psi, as does 2" type M copper. Copper is great for higher pressure as well, but is rather expensive in larger diameters compared to steel.
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Unread postAuthor: bluerussetboy » Sat Jan 05, 2008 7:56 pm

considering what 1" PVC is rated for 450psi and the pressures are below the rating. also considering the snowmaking equipment where i work uses the same PVC at the same pressure for extended periods with both water and air, i'm not too worried. thanks for the concern.

and thanks Fnord for the info
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Unread postAuthor: ALIHISGREAT » Sat Jan 05, 2008 8:01 pm

bluerussetboy wrote:considering what 1" PVC is rated for 450psi and the pressures are below the rating. also considering the snowmaking equipment where i work uses the same PVC at the same pressure for extended periods with both water and air, i'm not too worried. thanks for the concern.

and thanks Fnord for the info


well you will have to be carefull with it (more so than with copper or steel) because of cold weather or sunlight and another advantage of copper or steel is that they can be used all year round without any worry :)
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Unread postAuthor: SpudFarm » Sat Jan 05, 2008 8:02 pm

but steel dosent kill you if you drop it (mabe not copper either) im not the most experieced with high pressure all i have done is 300psi one shot in copper.
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Unread postAuthor: hi » Sat Jan 05, 2008 8:11 pm

i barely trust sch40 pvc at 135, no way i would do any more than 150, and even that is pushing it. copper or steel works better and looks better and is a lot safer. use metal pipe if you are doing any more than 150 psi.
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Unread postAuthor: SpudFarm » Sat Jan 05, 2008 8:15 pm

that`s why i never ever make cannon of somethig other than steel or copper (brass)
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Unread postAuthor: DYI » Sat Jan 05, 2008 8:20 pm

What your snowmaking equipment at work is doing is against building code, and would fail an inspection. PVC is not rated to be used as a compressed gas line unless it is encased in a shrapnel-proof shield.
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Unread postAuthor: SpudFarm » Sat Jan 05, 2008 8:22 pm

i think the snowmaking pipes is underground. correct me
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