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Need Qev Help

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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Need Qev Help

Unread postAuthor: dudeman508 » Fri Jul 18, 2008 9:37 pm

I looked all over the internet for instructions on how to make a qev ad i found to 2 videos on youtube but they were in french and it looks kinda like a piston valve but i still dont fully understand it, can anybody help
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Unread postAuthor: MrCrowley » Fri Jul 18, 2008 9:48 pm

A homemade QEV is a piston valve more or less.

A QEV as most Spudfiles members know it, is a metal valve usually bought from www.mcmaster.com. They are known to perform better then sprinkler valves of the same size and have been taken to pressures of over 500 PSI.

QEV stands for Quick Exhaust Valve and usually come in two forms:

The Shuttle:
Image

Which uses a small piece of plastic as the piston and is mainly found in the UK.

The American QEV (not sure what to call it)
Image

I can't remember if these use pistons or diaphragms. These are usually only found in America.



There are a few pictures of the internals of these QEV's on the forum somewhere.

Pretty much the QEVs made in those videos are just small bore, high pressure piston valves. Like piston valves, QEV's have three ports.
Barrel, chamber and pilot. On the valve they are labled as something else like EXH, IN and OUT if I recall correctly, I can't remember.

Here is an American QEV being used on a cannon:
http://www.antennalaunchers.com/tblpics/DSCN4627.jpg

It's a 3/4" QEV which can be bought for about $20US on McMaster and will out perform a 1" sprinkler valve.
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Unread postAuthor: frankrede » Sat Jul 19, 2008 12:12 am

I have found "Shuttle types" here in america from Fastenal.

http://www.spudfiles.com/forums/a-canno ... 12400.html
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Unread postAuthor: psycix » Sun Jul 20, 2008 5:50 am

A QEV is a commercially made barrel sealing piston valve.
Check out the "piston valves explained visually" thread in the howto section if you want to know how it works.
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Unread postAuthor: Hotwired » Sun Jul 20, 2008 9:47 am

Furthermore you don't make what we call a Q(uick)E(xhaust)V(alve) round here, you buy them.

The valves you make are called after the way they work: barrel sealers, chamber sealers and co-axials.

A QEV is what the commercially made ones are called.

Of course they operate in the same ways but it's just a way of differentiating them.

The french video clip is a barrel sealing piston valve.
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Unread postAuthor: daberno123 » Sun Jul 20, 2008 2:58 pm

@Frankrede

Is this the QEV you used on your "Cannon For A Friend"?

http://www.fastenal.com/web/products/detail.ex?sku=0443031

That would be great if it is, because using the store locater I've just realized there's a store 10 minutes form me. :D
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Unread postAuthor: VH_man » Sun Jul 20, 2008 4:36 pm

haha theres a store 10 minutes from me too!!!!

:smilebox:

(i just had to im kinda happy right now.......)
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Unread postAuthor: iisthemuffin » Sun Jul 20, 2008 5:01 pm

Wow. There are two that are about 15 minutes away from me. I may have to go purchase one of these.

Very good selection.
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Unread postAuthor: frankrede » Mon Jul 21, 2008 12:22 am

daberno123 wrote:@Frankrede

Is this the QEV you used on your "Cannon For A Friend"?

http://www.fastenal.com/web/products/detail.ex?sku=0443031

That would be great if it is, because using the store locater I've just realized there's a store 10 minutes form me. :D
Yep, thats the one!
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