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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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A question about safety

Unread postAuthor: lockmanslammin » Thu Feb 14, 2008 1:37 pm

I was just wondering, the other day as I was poking a projectile down my barrel...
it sure would suck if the gun suddenly went off and shot the ramrod through me or some thing or someone else. Of course I aim it away from people but, really, how hard would you have to bump the piston face with the ramrod to set off the gun? And I imagine your going to say, "well that depends entirely on the gun, the piston design and the pressure.
To this I say....The gun and valve design I just posted about the other day, topic "my first copper cannon and my first post", and whatever pressure you may want to put into the scenario.
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Unread postAuthor: jackssmirkingrevenge » Thu Feb 14, 2008 1:59 pm

It can happen, it helps to either poke your projectile down slowly or load it before pressurising.
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Unread postAuthor: bluerussetboy » Thu Feb 14, 2008 1:59 pm

just play it safe. load your ammo, then charge your weapon.

if your breech loading it shouldn't matter too much.


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Unread postAuthor: Fnord » Thu Feb 14, 2008 2:29 pm

Put a nail or screw through near the back end of the barrel to act as a stopper(of course, it helps to do this before you glue it together). Seal around the nail hole with superglue or epoxy.
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Unread postAuthor: pizlo » Thu Feb 14, 2008 3:44 pm

I'm lucky I'm using a sprinkler, I made a couple of rounds of 7 inch long screws ground down at the end, and epoxyed through the head of a nerf dart as a sabot. that could do some damage!
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Unread postAuthor: potatoflinger » Thu Feb 14, 2008 3:58 pm

Yeah, I would pressurize the launcher after you load it to be on the safe side, but it never hurts to be careful. With my piston cannon, I really have to be careful because I could accidently set it off with the ramrod, or it could be set off when I disconnect my bike pump from the pilot/fill setup, so the gun always has to be pointed in a safe direction. (which it should be anyway)
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Unread postAuthor: psycix » Thu Feb 14, 2008 4:57 pm

As ive heard sometimes, its not only the force of ramming against the piston, but also the air pressure you may create when pushing down a well-sealing projectile.
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Unread postAuthor: bluerussetboy » Thu Feb 14, 2008 5:47 pm

i watched one friend(silverdooty) use a very tight sweet potato in his sprinkler valve cannon. the cannon was only pumped up to 90 psi and it let loose from the air pressure in the barrel.

pizlo --- sprinkler valves aren't any safer than piston valves.


first load your ammo then fill your chamber.
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Unread postAuthor: Velocity » Thu Feb 14, 2008 5:59 pm

When I was first testing a 1.5" porting piston valve based in a 2" tee, the pilot valve was malfunctioning, so I decided to try to manually open the piston valve when it was pressurized at 20 PSI. I stuck a broom stick into the piston face, and pushed. It actually took a significant amount of pressure to force the piston back. So for valves this size and greater, I don't think the risk is too high.

However, smaller piston valves (and other valves) can be easily manually opened by accident, especially when you force down a tight fitting projectile down the barrel.
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Unread postAuthor: D_Hall » Thu Feb 14, 2008 6:49 pm

Call me stunned that this question is even being asked....


Load the projectile, THEN pressurize the gun.


(Yes, I know others have said it in this thread, but it bares repeating.)
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Unread postAuthor: MaxuS the 2nd » Thu Feb 14, 2008 7:28 pm

Why would you do it any other way anyway?
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Unread postAuthor: bigbob12345 » Thu Feb 14, 2008 7:32 pm

Ive had sprinklers go off while loading the projectile while pressureized and it is not fun to get hit by a peice of potato in the hand at 20psi.
I am now much more careful and never load it while pressurized.
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Unread postAuthor: lockmanslammin » Fri Feb 15, 2008 1:24 am

at 20 psi you say?.. see what made me think about it was after watching a soft little foam ear plug blow a hole through a beer can, I thought...yikes, imagine that hitting my fingers...
I'm thinkin there would be a little blood letting, maybe some really nasty looking bruising, and a whole lotta cussin'

Only reason I was(very carefully) loading after pressurizing was I was thinkin that the little burst of air that goes out the barrel right as the piston is sliding up to seat against it would push the projectile up the barrel a ways.
I just need to finish the bolt action and I wont have to worry about it anymore.
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Unread postAuthor: frankrede » Fri Feb 15, 2008 8:08 am

Yea its possible with a piston valve, I have down it before on accident.
witha 2" piston vlave with 3/4" barrel.
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Unread postAuthor: Ragnarok » Fri Feb 15, 2008 9:11 am

I prefer the pressurize, use the sliding breech loader, take off the safety ball valve that's between the valve and loader - then fire.

Absolutely no chance of pushing or knocking the valve open (because the valve and projectile are blocked off from each other until the last moment, and certainly no ramrod issues), and saves the projectile needing to be in place until you're nearly about to fire. And even if it were to go off - there's no chance I could get hit by anything.

I do put a lot of thought into safety. 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.
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