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Material for shrapnel shielding

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Material for shrapnel shielding

Unread postAuthor: zerodivide » Sun Sep 10, 2006 7:40 am

I've got a semi-working pneumatic which I may want to carry around pressurized for a few minutes before actually firing. So I'm planning on sleeving it in another tube to as a shield. What have you tried? The pressure is < 100psi with Sched 40. Anyone done burst tests to validate this?

1) Duct tape -- someone mentioned lots of duct tape would keep PVC shrapnel from flying. Saw some other post that said it was ludicrous.

2) ABS tube -- the tensile strength and the ability to stretch is supposed to stop the shrapnel. Again, saw another post somewhere that said this was hogwash and that sharp PVC will go through it.

3) A pant leg from denim jeans -- Hmmm?

4) Double thick PVC via couplers -- this may be harder to pull off depending on the dimensions and whether you can file off the divider properly. Also not applicable if you've already built the cannon.

5) Sched 80 tube -- A higher thickness tube, begs the question why you didn't use it in the first place. Only caveat is UV rays will make it brittle unlike ABS, so its shielding value will degrade over time.

6) Chikenwire -- hmmm?

7) ABS tube + galvanized iron sheet -- cut up and roll. Drill holes to bolt on -- just a brain storm, no idea if its practical.

8) ABS tube + fill foam -- just thought of this now -- a kind of ablative armor to absorb the kinetic forces before reaching the ABS. But then this may cause the end cap to fly instead if the gases don't escape from the tube.

Every shield works by absorbing the kinetic energy of the projectile. If a chamber can explode at a certain pressure I guess the best way to test it, short of blowing up a chamber, is to fire a projectile from a cannon to the material in question at point blank range going as close to maximum pressure as possible. Anyone tried similar shielding before? Or maybe dropped a pressurized spud gun?
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Unread postAuthor: sgort87 » Sun Sep 10, 2006 9:22 am

Oh oh! How about... nothing?!

If you use NSF-PW fittings and pressure rated pipe then you will be fine, especially if you are staying under 100 psi.
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Unread postAuthor: jrrdw » Sun Sep 10, 2006 9:27 am

I plan on shielding mine in 1/4 rat wire/square cage wire. I'm in the process of building the valve/chasis for it now.
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Unread postAuthor: rna_duelers » Mon Sep 11, 2006 6:11 am

Why bother,its rated for like 250psi so the bursting pressure is at about tripple that but dont drop it though.
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Unread postAuthor: clide » Mon Sep 11, 2006 6:40 pm

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Unread postAuthor: zerodivide » Mon Sep 11, 2006 7:34 pm

@clide
excellent link. Looks like short of a metal box its going to be hard to contain PVC fragments.
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Unread postAuthor: Mihlrad » Mon Sep 11, 2006 8:02 pm

Personally, i plate my pnuematics with reactive armor plating. You could also use a force field made of plasma that simply vaporizes the shrapnel. That could get pricey though.

If its pressure rated, it wont matter...
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Unread postAuthor: CS » Tue Sep 12, 2006 2:24 am

Mihlrad, thats interesting that you use reactive armor plating. Sounds cool I might have to use right now. Currently I sleeve my chambers with Levi pant legs that I induced to intense transistor diode radiation to realign the fibers creating a higher tensile strength resulting from bipolar forces.

You could also use a force field made of plasma that simply vaporizes the shrapnel. That could get pricey though. ~Mihlrad

Not really. Have you seen those cheap laser pointers at the china marts for $1? Anyways, as I understand if you hook the power inputs on the lasers from a high polarizing transformer you can actually get some destructive capablites. Then just wire in like ~50 laser pointers to melt the plastic in the event of a explosion, possibly preventing it if the sensor for the device was able to read the fault in the chamber wall. Wiring the device to detect the explosion would be the only hard thing to do.

Ive seen a lot of the Mexican stuccoers using chicken wire on houses before stuccoing to prevent from 'exploding' forces. The chicken wire offers a lot more strength to the structure, since in the event of some type of force the stucco breaks off not holding. I heard actually that some stuccoed houses in the Hurricane Katrina that didnt use chicken wire prior to the stucco ruptured in weak points and only generally cracked walls. The windows in the house act as a net to any high winds once the windows break. In hurricane winds the internal pressure the winds can produce in a house are quite excessive. Possibly this technique of chicken wire could be used for protection of chamber failure?
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Unread postAuthor: MrCrowley » Tue Sep 12, 2006 2:34 am

if its sch40 staying 100psi and under should be safe but wasnt there a thread about how one in every hundred and something batches of sch40 one has a failing point of like half the pressure its rated to?
best option not including sleeving or buying sch80 i would say is small gauge chicken wire
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Unread postAuthor: zerodivide » Tue Sep 12, 2006 9:05 pm

The reason for the question of sleeving is in event of accident. The casual spudder that fires it in his backyard probably doesn't need to worry about this. But scenario players with nerf/paintball/bb launchers have a higher chance of slipping/sliding on the field. If the pressure chamber happens to rupture it would be nice to have built some effective protection before the fact.

----

That stucco + chickenwire comment was kind of funny. I've seen the way bridgepillars have been built with metal bars in a mesh and concrete around it. Seems plausible ... interesting Mythbusters material.
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Unread postAuthor: Shrimphead » Tue Sep 12, 2006 10:07 pm

If you want to protect your chamber from getting dinged up when paintballing, I would suggest you just wrap it in foam that will absorb the shock.
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Unread postAuthor: MrCrowley » Tue Sep 12, 2006 10:38 pm

and always check your barrel/chamber/fittings for cracks after playing paintball or shooting the gun.
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