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Will it die?

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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Will it die?

Unread postAuthor: inonickname » Sat Jun 27, 2009 8:50 am

I'm about to order one of these 1/4" Bellpro QEV's for $35 aud posted, which is about as good as I can get without going ebay international.

Clicky.

After discussions with Carl he reckons the body should hold out at 300-400 psi. The main concern is the piston.

Basic question; will this hold up at around 300 psi?

And if not, does anyone know of a QEV available to Aussie gunners that will work well?

Barrel size it will be for is around 5mm.

Thanks guys

Edit: if it won't hold and there's no easily available QEV's I'll machine my own, I'd just rather order one seen as I want time over the holidays to work on it- school (and my access to a lathe for the time being) ends in 1 week..
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Unread postAuthor: mark.f » Sat Jun 27, 2009 9:04 am

Well, depends on the diaphragm material. The body will be plenty strong enough, but if the diaphragm is thin or made of a weak rubber, it could pop on you at those pressures.

I would go ahead and buy it, and if the diaphragm is too sickly for the task, I would just machine a piston, or a support for the old diaphragm.

Good luck.
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Unread postAuthor: inonickname » Sat Jun 27, 2009 9:07 am

Thanks. I'll wait for more responses, it'd be great if someone could chime in who has one of these (or similar).

If I can't find someone else who's used them at these pressures then I'll machine an integrated QEV/bolt action breech.
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Unread postAuthor: Dave_424 » Sat Jun 27, 2009 11:21 am

I'd say go for it, the body will be fine and the piston SHOULD hold up, just make a new one if the other one fails.

But I would want to "Pressure Test" it to slightly higher pressure than you would be running it at so that it doesnt turn into an unexpected burst disk valve

Dave
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Unread postAuthor: inonickname » Sat Jun 27, 2009 11:47 pm

Bout to order it, $34 shipped.

I'll dismantle it before use and see what it looks like. I'll backfill any dead space with epoxy, and reinforce the piston if needed.

I already have a nice thick aluminum chamber turned, polished and knurled at the ends but I may make it a bit larger seen as it is so much larger than the barrel.

Then turn up a nice aluminum bolt action, make a bipod and I'm rolling.

Thanks everyone :wink:
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Unread postAuthor: Clarke » Sun Jun 28, 2009 2:42 am

Yea ive also been looking at getting a 1/2" Bellpro QEV and want to take it to 250-300 psi but im not sure how well the plastic shuttle cup/piston will hold up to the HP. Keep us posted on how it goes mate.
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Unread postAuthor: inonickname » Sun Jun 28, 2009 3:21 am

Sure thing! I'm ringing them tomorrow to ask if they'll do bank transfers, otherwise I have to wait for money to transfer from my bank to paypal, then order it. So it could be up to a week.

By nature, the 1/4" QEV would have less force exerted on it due to a lower surface area but it should show up if there's any problems with using it at 300.

I may yet get the 1/2" one, a few $ to go up from 1/4 to 1/2 isn't bad. Not like a 1/2" QEV porting to a 5mm barrel is overkill..

I'll keep ya posted
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Unread postAuthor: Clarke » Sun Jun 28, 2009 9:33 pm

Mitchza89 has used a 1/2" Bellpro on a semi auto gun of his before but im not sure of the max pressures he used, heres the link;

http://www.spudfiles.com/forums/the-was ... 18036.html

I Messaged him a few weeks ago asking him about Bellpro QEV's, heres a quote from his PM,

"The Bellpro QEV's aren't too bad at all. I use 6-8mm bearings. Despite being a 1/2'' QEV, the sealing face that the piston sits on is about 8 or 9mm. Perfect for what I need but with a 12mm (1/2'') copper barrel, it's not too bad. A little constricted as you would expect but still good."

So i will be buying a 1/2" QEV and whacking it on a 6mm ID barrel for .22 pellets, should be some fun at 300 psi :D not Overkill just A LOT more fun :twisted: lol
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Unread postAuthor: THUNDERLORD » Sun Jun 28, 2009 11:26 pm

Off topic reply edited...
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Unread postAuthor: inonickname » Mon Jun 29, 2009 3:24 am

Cool, I might go for the 1/2" even though it would be less smooth than the 1/4" one. If only they did 3/8" :roll:
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Unread postAuthor: inonickname » Tue Jun 30, 2009 5:47 am

Ordered the 1/2" Bellpro QEV. He's getting back to me with an invoice for a money transfer.

The 1/4" may have been a slightly better idea. Less surface area to fail in..

But the 1/2" will give me moar barrel options, even up to .378.. And it's not like it would be impossible to reinforce
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