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safety question (call me paranoid but.....)

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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safety question (call me paranoid but.....)

Unread postAuthor: rgormley » Mon Oct 09, 2006 8:32 pm

I have a air gun using PN12 rated pvc pipe (173 PSI)
air chamber is 1 meter by 50mm diam pvc, orbit sprinkler valve
Muzzle is 30m by 90cm

So the question is will the PN12 (173PSI) rated pressure pipe be safe at 125psi (my max pressure)

Secondly there must be a way to protect the chamber from a possible explosion...

my idea: cover the chamber with 2 x jeans leg (heavy weight denim) then cover the hole thing again with a 60mm (or whatever is close) pvc pipe over the top of the jeans.

This should stop any "bitts" getting out?
Maybe I’m scarred of this thing but i prefer to be safe than "it will be ok"

Any ideas /feed back please......

Cheers,
Richard
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Unread postAuthor: Atlantis » Mon Oct 09, 2006 8:42 pm

Wrap it in chicken wire fence. Jeans might rip, it's been proven that duct tape is useless.
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Unread postAuthor: Flying_Salt » Mon Oct 09, 2006 8:44 pm

Well, why use it if there's danger of being stabbed?
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Unread postAuthor: Extrusion » Mon Oct 09, 2006 8:45 pm

It will probably be ok because i think there rating is like 3X lower then what it will accually explode at (i think) but thats with water not air and wrapping it in denim would probobly help but it might just completely explode the entire cannon and sending denim filled with bits of pvc at you lol.

If all else fails just dont take it to 125 psi :P
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Unread postAuthor: FreakyShotGlass » Mon Oct 09, 2006 8:54 pm

They did a test on spudtech to see if wrapping anything around your chamber actually helped in the case of an explosion, IT DIDN'T. No matter what is around your chamber, denim, tape etc. it will still send shrapnel flying if it goes. However another layer of PVC pipe was not tested and I think that it will prevent most of the shrapnel.
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Unread postAuthor: zerodivide » Mon Oct 09, 2006 8:58 pm

Previous thread on shrapnel shielding material. Look for the link by clide. According to this, nothing short of a metal shield will stop exploding shrapnel. I intend to replace my chambers with aluminum when it becomes convenient.
http://www.spudfiles.com/forums/viewtopic.php?t=3599&
http://www.network54.com/Forum/167582/m ... +Duct+Tape

Note that PVC psi rating is for water. The last post I've seen mentioned a 1/3 rating when dealing with air vs water. Also there is a derating factor for PVC depending on temperature. These are all guidelines. You may luck out the first few times you overpressurize but I haven't seen any long term studies.
http://www.harvel.com/pipepvc-sch40-80-derating.asp
http://www.pipa.com.au/docs/PV006.html
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Last edited by zerodivide on Mon Oct 09, 2006 9:06 pm, edited 1 time in total.

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Unread postAuthor: rgormley » Mon Oct 09, 2006 9:02 pm

salty, i drive a car and i can crash it or be crashed into (many things beyond my controll) but i still drive....

i still wish to play with spud guns just would like to play it safe

i dont live in handfull of cotton wool balls....
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Unread postAuthor: Flying_Salt » Mon Oct 09, 2006 9:10 pm

Hm If I were you I would keep it at 100 psi tops, but that's just me, and I have too much to live for to have my jeans in my gut...
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Unread postAuthor: rna_duelers » Tue Oct 10, 2006 6:08 am

People Australian PVC bursts at 3x it running pressure,so if its PN12 thats 36bar burst pressure thats the safety margins they use so dont worry about it just "exploding"but do worry if its charged full of air nad u drop the chamber on a ahrd surface as PVC is brittle stuff.
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