how do QEV's work?

[slade]

ive searched around but i cant find the answer. how do QEV's actually work? does anyone have a diagram?

[FSU_Paintball]

QEVs go on a ram

A ram works by sending air to one side or another. The faster the ram can move back and forth, the faster your gun will "cycle"

In very simple terms...

But because it's going back and forth, it's trying to push air out of the way so that it can move, which isn't always easy.

A QEV stands for Quick Exhaust Valve. They typically go on the end of a ram, so that when it's moving back and forth, it can very easily vent out the air it's pushing around. The air goes through the QEV and out of the ram. It's like an escape valve for extra air.

This means that since the ram doesn't have to push so hard to "squish" the air out of the way while the ram shaft moves, it can cycle faster. Which makes your gun faster.

[evilhomer]

I think what he was asking was how do the QEV's work, not what they do... Like how do the QEV's actually exhaust the air...

[noahyay]

its like a t fitting with a little rubber piece that moves back and forth

T the bottom part of the t goes to the ram
air goes in the right side
and exausts out the left
when the air from the 3 way is going into the ram, it pushes the rubber gasket ({ in the diagram) to the left and seals the exhast
when the air pressure drops slightly, then the gasket moves and the air can get out the left side without having to travel down the hose


dont know if this will work but here it goes:
______________
exhaust{
here_ { _____ < air goes into ram here
...................ram here ....
.....................................-----------back block
^other qev here

[Gunga]

Courtesy of our friends at Clippard.com and their nifty catalog...

[slade]

ahh, thanks gunga, thats what i was looking for. i already know what it does; thats easy to find out, its everywhere on the internet. anyone with 999 posts on here should know what a QEV is by now. what i wanted to know is how it does it.

[Gunga]

Found a QEV animation today.

[JimmyBeam]

QEVs go on a ram

.

not anymore, they now are used to replace the middle banjo fitting on the Ion. you can then drop your dwell to about 5 and get ~500 shots per 1k in pressure off a 68/45

[SlartyBartFast]

not anymore, they now are used to replace the middle banjo fitting on the Ion. you can then drop your dwell to about 5 and get ~500 shots per 1k in pressure off a 68/45

Uhm, the ION bolt is just a ram. So I don't know why the "not anymore" qualifier is necessary.

The QEV will still be doing EXACTLY the same thing as always. Letting air exhaust through a big local opening instead of the much smaller (and remote) valve exhaust.

[SlartyBartFast]

Found a QEV animation today.

Did you see their quirky paintball animation?

http://www.pneumadyne.com/industries/entertainRecreation.cfm

[slade]

btw in case anyone is wondering, im posting this (besides just to obtain knowledge) for a non-paintball related use. does anyone know if, and by how much, a QEV will reduce the air flow rate?

[SlartyBartFast]

does anyone know if, and by how much, a QEV will reduce the air flow rate?

I'm assuming you mean INCREASE the flow rate.

The specifications of the various parts you intend to use will give you those details.

Look at the flow rate of the exhaust from your valve and the flow rate of the QEV exhaust. That'll be your minimum increase (as there would undoubtably be flow restrictions in the piping back to the valve that will limit the valve exhaust rate further).

If you're worried about the QEV reducing flow when the valve is providing pressure through the QEV input, well you make sure it doesn't reduce your flow by checking the QEV's rated flow rate through the input is greater than the flow rate provided by the valve output.

[slade]

I'm assuming you mean INCREASE the flow rate.

The specifications of the various parts you intend to use will give you those details.

Look at the flow rate of the exhaust from your valve and the flow rate of the QEV exhaust. That'll be your minimum increase (as there would undoubtably be flow restrictions in the piping back to the valve that will limit the valve exhaust rate further).

If you're worried about the QEV reducing flow when the valve is providing pressure through the QEV input, well you make sure it doesn't reduce your flow by checking the QEV's rated flow rate through the input is greater than the flow rate provided by the valve output.

no, i meant decrease. of course an exhaust valve will allow the cylinder to vent air faster, resulting in faster cycling, but i was wondering if the geometry of the valve will reduce the flow rate while air is entering the valve, compared to a normal fitting.