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My new valve design

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: jjjd » Sat Mar 24, 2007 7:30 am

try to make it so that instead of the small vavle moving the rod, have it somehow realeave packpreasure off the big piston, something like this, i dotn know if it would work but whatever
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Unread postAuthor: boilingleadbath » Sat Mar 24, 2007 11:17 am

Well, the dump piston in that design couldn't be bigger than 20mm or so (assuming that it's to scale), so we can't be dealing with much more than 50 pounds.

But that's still quite a bit of force... plus, the flow will be rather sad for the amount of work you put into it.

I think you'd be better of to just make a (small) valve that will open at a certain pressure and, once open, will <i>stay</i> open until the pressure drops quite a bit.
One would then use that to pilot a more typical valve.

As to the design of this small trigger valve, I'd go with something like a poppet valve installed "backwards" with an O-ring on the shaft near the head.
Such would have take much force to open (due to the small diameter shaft), then stay open due to pressure acting on the large diameter head.
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Unread postAuthor: .:: :TomDom: ::. » Sun Mar 25, 2007 3:48 am

chaos; thnx for the heads up on u knowing how to weld that, but i dont think that i will be able to do that, of corse i could be mistaken so i'll try it sometime. jrrdw; yes i can see where your coming from, that can be solved a number of ways like having the spring like you said, which i probably will but it could slow the big piston down when it goes to release the air, so i'll have to think about it. hotwired; i know what your saying, ive thought about it lots before putting the valve up on here, im solving it by putting some metal behind the metal from the small piston, so it wont bend or jam or anything. jjjd; thats a good idea, i could make it work coz that design u have there wont because the pressure on both the front and back of the dump piston is the same, which can be altered. boilingleadbath; im trying to make the dump piston as big as possible, which is about 25mm or 30mm if my school wants to buy a 30mm drill bit, or i might, then that will be great 8) but yeah that animation is definatly not to scale. and thanks every1 for the comments so far, sorry about the grammar.
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