SpudFiles

Would a diaphram QEV perform just as well as a piston QEV?

Not familiar with any QEV using a piston, have any documentation? Or is this just a incorrect speculation?

Nevermind. I am confused.

Well, I just bought a QEV from a local retailer, and they had no piston type QEVs, so I just got the diaphram one. I wasn't sure if they had not as good performance because sprinkler valves dont have that good of flow, and the diaphram QEVs were similiar to that of a sprinkler valve.


--They do make piston type QEVs

I think that hotwired's copperhead prime uses a piston, but i have no proof.

yeah eaxctly that copper head prime has a "piston" type qev, the actual piston is built into the valve. The piston doesnt work exactly like the common barrel or chamnber sealing piston that are homemade.

correction, they do work the same way.
You just don't know it.
The piston is always built into the valve btw, because the piston is the valve

Sprinkler valves have lower flow because of their 180*s of twists and turns. A diaphragm valve will perform better for shorter barrels because of the faster opening time, pistons a little better for longer barrels because of the slightly increased flow.
QEVs usually have either a diaphragm or a very short piston.

Yes mine does have a piston QEV - its more of a barrel shape.

You can see the two types here: http://www.airlines-pneumatics.co.uk/we ... ?SubCat=85

The diaphragm one has a flattened out shape where the rubber disk is clamped in the body.

The piston in the piston ones is a hard rubbery shape that physically moves up and down the valve body and isn't fixed at any point you can see what it's like here: http://www.uksgc.co.uk/forums/index.php ... ic=475&hl=


If you click on the airlines link you can see the flow available in the diaphragm QEV's but that information isn't available for the piston ones so I couldn't say which was better.

I personaly haveboth diphragmn and piston QEVs.

I much prefer the piston one, mainly because it is smaller in size.

I have no clue about power differences, but i'd assume they are the same(ish)

(Porting and filling holes all same for piston/dia)

hi wrote:I think that hotwired's copperhead prime uses a piston, but i have no proof.

he uses a 1/2 i use a 3/4 and heres some photos of mine




its a piston but flat
hope this hels

Thanks for the advice. Should I spend the time getting a piston QEV or just stay with my diaphram QEV I already have?

Unless you're in the UK you're going to have fun trying to find piston QEVs like that. The only located supplier for that type in the US only deals with businesses.

I'm sure there are other models of piston QEV's available but I'm pretty sure the performance is similar between diaphragm and piston models.

Piston ones just look better