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A question about safety

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: Hotwired » Mon Feb 18, 2008 10:46 am

My firing checklist has pressurising before loading because like rags cannon mine has a safety valve on the QEV trigger line (patent pending) which prevents the trigger from activating the QEV if pulled.

Obviously it can't be on while pressurising so its not safe to have the cannon loaded at that time. So the air goes in, safety goes on then the projectile is loaded.
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Unread postAuthor: D_Hall » Mon Feb 18, 2008 11:32 am

Ragnarok wrote:A lot of people may not like my decision to use a full bore ball valve after the main valve, but it really has it's safety benefits.

Actually, I'd call that one a great idea.
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Unread postAuthor: Ragnarok » Mon Feb 18, 2008 12:24 pm

D_Hall wrote:Actually, I'd call that one a great idea.

It's certainly safer, but it does add a little length and dead volume.

However, I'm sure it's effect on the performance is minimal, although opinion seems to be split as to the appearance. I personally don't think it looks that bad.

With a 300 psi cannon, you hardly want it going off unexpectedly.
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Does that thing kinda look like a big cat to you?
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Unread postAuthor: lockmanslammin » Mon Feb 18, 2008 1:40 pm

I have since carefully tested weather the projectile moves if I load it before pressurizing, and it doesn't so no worries now. I have just been loading before pressurizing, Thanx for all the responses guys. Lock
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Unread postAuthor: jimmy101 » Mon Feb 18, 2008 3:47 pm

Instead of a full bore safety valve you could install a small relief valve between the ammo and main valve. Ram the ammo with the relief open and the chamber unpressurized. Then pressurize the chamber. If there is a bit of leakage while pressurizing it'll exit via the vent instead of pushing the ammo out of the barrel. Close the vent before firing.
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