Hey guys!
So here I have another stupidly simple question. As some of you know, I'm building a 1/2 inch piston valve-operated cannon, and I'm trying to find myself a nice QEV to fit it. Recently I stumbled across several items called a shuttle valve, and they look almost identical to the QEVs that I've seen. Are shuttle valves and QEVs just the same thing? Does one of them perform better than the other?
Thanks again,
tater slayer
Shuttle Valve = QEV?
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tater slayer
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lockmanslammin
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A shuttle valve is not the same thing as a qev. I suppose you might be able to use it, but it would require a lot of extra parts and strange routing to get it to do the same job. Look up shuttle valve on Google, and you will see what I mean. It is designed to have two different pressure supplies to feed a single device, and it selects the supply with a higher pressure to feed the device. At least that is one use as I understand it. I'm sure it has some valuable uses in this hobby, but replacing a qev isn't one of them.
Of course there may be someone with more knowledge on the topic than I have, that will have a better/different answer than me.
I'm kind of glad you posted the question though, as I have heard of shuttle valves before but didn't know how they worked. It's always nice to have a new tool in mind when brainstorming solutions to build problems.
Chris
Of course there may be someone with more knowledge on the topic than I have, that will have a better/different answer than me.
I'm kind of glad you posted the question though, as I have heard of shuttle valves before but didn't know how they worked. It's always nice to have a new tool in mind when brainstorming solutions to build problems.
Chris
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tater slayer
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Alright, that's good to know! Thanks for your help!lockmanslammin wrote:A shuttle valve is not the same thing as a qev. I suppose you might be able to use it, but it would require a lot of extra parts and strange routing to get it to do the same job. Look up shuttle valve on Google, and you will see what I mean. It is designed to have two different pressure supplies to feed a single device, and it selects the supply with a higher pressure to feed the device. At least that is one use as I understand it. I'm sure it has some valuable uses in this hobby, but replacing a qev isn't one of them.
Of course there may be someone with more knowledge on the topic than I have, that will have a better/different answer than me.
I'm kind of glad you posted the question though, as I have heard of shuttle valves before but didn't know how they worked. It's always nice to have a new tool in mind when brainstorming solutions to build problems.
Chris
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tater slayer
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Alright, now I'm really confused. After some further research, I've found a TON of valves that claim to be both quick exhaust and shuttle valves. What do I believe?
Example: http://www.ebay.com/itm/LOT-2-PARKER-OR ... 58b5e0de4d
Example: http://www.ebay.com/itm/LOT-2-PARKER-OR ... 58b5e0de4d
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lockmanslammin
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Ok, I'm confused too, maybe shuttle qev, is just a different way of saying piston qev.
Hopefully someone else will answer and clear the confusion.
Chris
Hopefully someone else will answer and clear the confusion.
Chris
You are right, from what I have seen in the past shuttle valves are very similar to quick exhaust valves, and work similarly to how you described earlier.
They might look very similar internally, but they are not designed for 'quick exhaust', you might get significant air loss, performance issues, the valve not re-seating, or times when depressurizing the pilot fails to open the valve whatsoever with a shuttle valve, as they are not designed to actuate on the 'back pressure' dumping the pilot volume would create.
As of that, for your purposes I would probably stick to a Qev,
but I am no expert in pneumatic control devices so I could be wrong in this.
They might look very similar internally, but they are not designed for 'quick exhaust', you might get significant air loss, performance issues, the valve not re-seating, or times when depressurizing the pilot fails to open the valve whatsoever with a shuttle valve, as they are not designed to actuate on the 'back pressure' dumping the pilot volume would create.
As of that, for your purposes I would probably stick to a Qev,
but I am no expert in pneumatic control devices so I could be wrong in this.