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tri-valve pneumatic

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: Mitchza89 » Sat Feb 16, 2008 8:52 pm

Only problem is that alot of people hate having to change disks every shot :?

That's what has turned me off em' a little bit.
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Unread postAuthor: EGOed » Sat Feb 16, 2008 9:00 pm

This is exactly my point guys, you are using a double standard here regarding these valves....If your PVC air chamber is rated for 260psi and you say to be on the safe side never go over 90 psi........Why would you take a PVC sprinkler valve to 150psi when when this is its max pressure rating......I am well aware of the difference between fluid and gas pressure dynamics but I dont see the logic here.....The valves are subject to the same drawbacks as using PVC pipe for compressed gas......I for one would never take one of these valves over 90 psi ....an industrial QEV is only rated for 150psi and is much better constructed than a $15 water valve from Lowes.....Just wondering what guys think because I have seen these valves crack around the threaded sockets and have seen blowguns break off the modded pilots.
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Last edited by EGOed on Sat Feb 16, 2008 9:12 pm, edited 1 time in total.

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Unread postAuthor: Mitchza89 » Sat Feb 16, 2008 9:04 pm

But with spudguns, when is anyone using any part for it's intended purpose? I'm doubtful that when QEV's, plumbing parts and irrigation equipment was first designed and released to the public, the designers and manufacturers wouldn't have thought we were gonna do what we do with it haha :D.
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Unread postAuthor: MrCrowley » Sat Feb 16, 2008 9:08 pm

EGOed wrote:This is exactly my point guys, you are using a double standard here regarding these valves....If your PVC air chamber is rated for 260psi and you say to be on the safe side never go over 90 psi........Why would you take a PVC sprinkler valve to 150psi when when this is its max pressure rating......I am well aware of the difference between fluid and gas pressure dynamics but I dont see the logic here.....The valves are subject to the same drawbacks as using PVC pipe for compressed gas......I for one would never take one of these valves over 90 psi ....an industrial QEV is only rated for 150psi and is much better constructed than a $15 water valve from Lowes.....Yet you say It is safe to take a sprinkler valve to 150 psi when you are not using it for its intended purpose ?


It's intended purpose is no different to what we are using them for aside from the substance used.

If they blew up at 150psi, the rating would probably be only 100psi, if that.

It's like when you take apart a Dell computer or similar, which can void the warranty. It's so that if you take it apart and a part FUBAR's, then you can't hold Dell responsible.

With a sprinkler valve, they're saying if you take it past 150psi and it blows, they may get minimal bad publicity, but they can at least say it was recommended not to exceed 150psi for safety reasons.

260psi rated PVC pipe can go far beyond 300psi, not that I would take it that far. 260psi is alot more then 150psi, and I personally wouldn't exceed 170psi with PVC.

I doubt a sprinkler valve would blow up, as in shrapnel, at pressures under 220psi, it may leak, but I doubt it will blow.

So by keeping to, or under, 150psi, we, according to the manufacturer, are safe.

150psi rated QEV's have been taken far beyond 200psi, same with 90psi rated blow guns. They have been used up to 200psi as well I believe.


I'm not sure if they say not to use sprinkler valves with air, I suspect they would like the PVC manufacturers, but that's only because of the difference in failure between 150psi of air and 150psi of water.

As you already know, 150psi is going to give far more energy to the plastic shards then a liquid would, so they are only doing this to cover their backs incase there is a production failure in one of the valves and it blows up.
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Unread postAuthor: EGOed » Sat Feb 16, 2008 9:20 pm

Yeah , No doubt sprinkler valve manufactures would start putting warning labels on the boxes if they only knew what we were doing with them...lol...Not for use with cannons , paintball mines, LAW rockets, Spudguns .....the list goes on and on.
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Unread postAuthor: MrCrowley » Sat Feb 16, 2008 9:24 pm

EGOed wrote:Yeah , No doubt sprinkler valve manufactures would start putting warning labels on the boxes if they only knew what we were doing with them...lol...Not for use with cannons , paintball mines, LAW rockets, Spudguns .....the list goes on and on.


Ha! Surprised they haven't already. I wonder if they noticed a huge surge in sales of sprinkler valves over the last few years...

It would certainly be interesting if they did directly address spudguns with their sprinkler valves. Maybe they could make ones just for spudguns :)
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Unread postAuthor: EGOed » Sat Feb 16, 2008 9:27 pm

Hmmmm , Maybe you should patent one MrCrowley....Please make it out of aluminum and be rated for at least 250psi.
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Unread postAuthor: Mitchza89 » Sat Feb 16, 2008 9:32 pm

Havn't people made Chamber Sealing Valves before though?
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Unread postAuthor: EGOed » Sat Feb 16, 2008 9:42 pm

Boy would I love to see the expression on the Rainbird CEO's face if he saw the suicide bomber vests I made from his sprinkler valves.....LOL.....
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Unread postAuthor: MrCrowley » Sat Feb 16, 2008 9:44 pm

EGOed wrote:Boy would I love to see the expression on the Rainbird CEO's face if he saw the suicide bomber vests I made from his sprinkler valves.....LOL.....


I hope you are joking :shock:
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Unread postAuthor: EGOed » Sat Feb 16, 2008 9:57 pm

Well, No.........I own a paintball field and specialize in putting on very realistic wargame scenario's........This was one of the most intense games we ever did ...The only way to take out a suicide bomber before he detonated the vest was with a head shot......The small air cannons in the back pouch of the vests blew out powder charges 12 ft into the air and eliminated players within a 20 ft radius......You should have seen the I.E.D's we used for the game.....Powder clouds were unbelievable.
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Unread postAuthor: MrCrowley » Sun Feb 17, 2008 12:06 am

Oh I thought you meant a proper bomb. Scenario is all good :)
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Unread postAuthor: dinsdale » Sun Feb 17, 2008 2:39 pm

i was going to post pics of my idea but i dont have an image hosting site set up.
i like the idea of sprinkler valves because it is what i am familiar with, i built one piston valve before and it didnt work out too well. i have an inline abs pneumatic with a 3/4 inch orbit sprinkler valve rated at 80 psi, i have taken this cannon past 160 psi probably well over a hundred times. and i can launch a potato 2000 yards+ from a 2 inch barrel with this setup. i plan on using a
2 and a half inch barrel for this one and i'm aiming for a 5000 yard range, hopefully at 125 psi, although it might get higher pressure. some parts of this new cannon will be made of steel, such as the breech and my blowoff manifold. i can get the sprinkler valves cheap enough that its worthwhile to me instead of the time spent on a piston. I don't like burst disks either, i want it to fire the instant i trigger it, not delayed
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Unread postAuthor: DYI » Sun Feb 17, 2008 6:12 pm

i have an inline abs pneumatic with a 3/4 inch orbit sprinkler valve rated at 80 psi, i have taken this cannon past 160 psi probably well over a hundred times. and i can launch a potato 2000 yards+ from a 2 inch barrel with this setup


My BS-o-Meter exploded when I read that post, and I don't think its a coincidence. I'm going to refrain from sueing you for the various shrapnel wounds and fire damage that you caused, but seriously, what the f*ck were you smoking when you wrote that?

The average particle speed in air is ~1600 fps. At that speed, a 100g projectile with a drag coefficient of 0.5 would travel roughly 470 yards. If you could somehow get a muzzle velocity of 16 000 fps (~Mach 14), maximum range would increase by only 250 feet or so.

And to give you an idea of what it takes to actually get a 100 gram, 2" tater up to even 1600 fps: my SCTBDC, the 2nd or 3rd most powerful cannon here, can achieve slightly over 1000 fps with a 100 gram projectile, and that is using 170 cubic inches of 500 psi nitrogen, a 2" burst disk valve, and 12' of barrel.

I believe that with a streamlined, fin stabilized and saboted tungsten carbide dart I could achieve over 2000 yards, but you haven't got a hope.
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Unread postAuthor: ShowNoMercy » Sun Feb 17, 2008 6:14 pm

Even without any math whatsoever, giant pumpkin cannons have trouble shooting that far, what makes you so special?
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