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Hunting for a particular Valve

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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Hunting for a particular Valve

Unread postAuthor: thatguydionysus » Fri Nov 16, 2012 11:59 am

It should have 3 ports.
In
Out
Pilot.

Air should flow with little to no constriction from the IN port to the OUT port.

When pressure ~= to the Pressure of flow from the IN port is applied to the pilot the valve should close off the IN port stopping flow to the out port.

Pressure from the Pilot Should not leak to the OUT port.

When the pressure in the Pilot port is release the pressure from the IN port should open the valve once again allowing flow with little to no constriction from the IN port to the OUT port.

a globe valve where the plug is pneumatically actuated would be an example of what I'm looking for.
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Unread postAuthor: POLAND_SPUD » Fri Nov 16, 2012 12:15 pm

it seems that what you want is an air actuated 3 way valve
though I don't get this part
When pressure ~= to the Pressure of flow from the IN port is applied to the pilot the valve should close off the IN port stopping flow to the out port.
Does it have to be equal ? is it crucial ? or is it just I wrote this because
I am gonna use air from the tank that is also attached to port IN so I wrote it here without thinking (ie it isn't a real requirement)
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Unread postAuthor: thatguydionysus » Sat Nov 17, 2012 11:59 pm

it is extremely crucial. the idea is that the valve will both trap the pressure contained downstream from the valve through the OUT port, and will lock the valve preventing flow after that pressure has been released.


step 1 allow air of desired pressure flow through IN port to OUT port.
step 2 allow pressure to build in pilot port from the OUT port.
step 3 allow valvle to close self given that the pressure downstream of OUT port is ~= pressure upstream of IN port and thus pressure behind pilot is also ~= to pressure upstream of IN port.
step 4 fire canon venting pressure downstream of OUT port. pilot port maintains its pressure via check valve.
step 5 reload cannon
step 6 vent pressure behind pilot opening valve.
return to step 1

wituout this valve several problems occur.
1 the canon cannot be reloaded
2 the canon can never completely vent the chamber into the barrel
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Unread postAuthor: sagthegreat » Sun Nov 18, 2012 12:03 pm

Please refrain from talking about hunting, forum rules

Jk :P, ok all jokes aside

i dont understand ur question, so is it liek a qev?
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Unread postAuthor: POLAND_SPUD » Sun Nov 18, 2012 12:23 pm

it is extremely crucial. the idea is that the valve will both trap the pressure contained downstream from the valve through the OUT port, and will lock the valve preventing flow after that pressure has been released.
I don't get it. What do you want to achieve with this valve ?


Can't you just use a 3 way valve ?
I suspect you don't really need this special valve

this is how this is normally done:
Image
Spend some time analysing it. the main part is the 3 way valve - it first allows filling the chamber and then pilots the QEV and blocks off flow to the chamber at the same time


you can either get a 3 way like the one I used or a slide valve (which is a kind of 3 way valve too) -> here is jsr's thread on it ->
http://www.spudfiles.com/forums/semi-au ... 23626.html
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Unread postAuthor: jsefcik » Sun Nov 18, 2012 11:10 pm

get a dust collector valve is has all three things your looking for and its plenty powerful
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Unread postAuthor: jackssmirkingrevenge » Mon Nov 19, 2012 2:14 am

sagthegreat wrote:Please refrain from talking about hunting, forum rules


:D :D :D
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Unread postAuthor: thatguydionysus » Mon Nov 19, 2012 4:17 pm

Thanks for the replies. but I think I've managed to design a useable valve that will meet my scheme.

wish me luck I'm off to scheme!
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