QEV wont work

[Cosmic Muffin]

hey all, i bought this off ebay the other day and realised the pilot thread is 3/8in. so i epoxied a 1/4in a 9bar pop off valve. and used that to actuate it. but it just wont work... i bought a QEV so i wouldnt have to stuff around with pistons and things because i can never seem to get it right. so im very frustrated that it wont work. any ideas as to why?

http://cgi.ebay.com.au/Pneumatic-Quick- ... 3ca1f78e9c my mistake.. this is the one

EDIT
sorry bout the double post, been off spudfiles for so long ive forgotten the forum rules ><

Edited by jrrdw, fixed link double post.

[jackssmirkingrevenge]

When you say "won't work", what do you mean exactly?

Does the safety valve "pop" but the QEV doesn't actuate?

Does the safety valve just "hiss"?

Does it leak out of the outlet port?

How exactly are you feeding air (pilot side/chamber side), at what rate, and what is the feed pressure vs pop-off pressure?

A photo of your setup would be most helpful.

If for example you're feeding from the chamber side, the QEV needs to be modded to function correctly.

There are many parameters that could be off so again a more detailed description or better yet a photo or diagram of what you're doing would help us help you

[jrrdw]

I was given 2 of these valves and I can get it to work once but have to dismantel the pilot to reseat the piston before the chamber can be refilled for another shot. When I get more time to test with it I'll figure something out...

[Cosmic Muffin]

Ok jack, I've been filling it from the chamber side. It's rated to 140psi and I've only taken it to about 50. When I pull the relief valve the air just hisses out of it. Not out of the port or barrel end. It seems strange that the qev doesn't have a spring.. And the seat is on the pilot side of the valve. Coul I possibly have it round the wrong way? I thought the pilot was the hole most visible in the attached picture

[jhalek90]

i assume you have it hooked up wrong.

also, most QEVs wont fill from the chamber side, unless you mod them.

[Gun Freak]

First of all why didn't you just buy a bushing for the pilot...

[POLAND_SPUD]

Gun Freak has just nailed it

epoxy might be useful but in many cases the process looks more like:

one part + second part + epoxy = something that doesn't work and is permanently bonded together

[jackssmirkingrevenge]

one part + second part + epoxy = something that doesn't work and is permanently bonded together

Used to be more often than not the story of my early development, but not necessarily the culprit in this case, especially if he's filling from the chamber side of an unmodded QEV or has got the porting wrong.

Have a look at the attached diagram, have you got the ports right?

[Gippeto]

Try filling from the pilot. Should work.

Can mod for chamber side filling by adding a spring, and tiny eq hole IIRC???

[jackssmirkingrevenge]

Can mod for chamber side filling by adding a spring, and tiny eq hole IIRC???

What would Brian Boitano do
If he was here right now,
He'd make a plan
And he'd follow through,
That's what Brian Boitano'd do.

[Cosmic Muffin]

Yeh I didn't buy a budging cos I knew I'd never find them, and I'm an Australian, I improvise . Even if I did mess up the epoxy Job it's still fixable. And I've been trying to pilot it from the R jack, just realized it's probably P that's "pilot" and the reason it won't wok when it's the other way round is because I'm not filling from the pilot. Would I be right?

[jackssmirkingrevenge]

it's probably P that's "pilot" and the reason it won't work when it's the other way round is because I'm not filling from the pilot. Would I be right?

P is your pilot, A is your chamber and R is your barrel - if that's not the way it's hooked up, it's not going to work.

[Cosmic Muffin]

Problem solved you blokes can expect a mean bolt action smoothbore within the next few days

[jackssmirkingrevenge]

Good to hear so it was hooked up the wrong way round?

bolt action

Ah, thought the pop-off meant it would be full auto

[Zeus]

3/8 to 1/4 inch bushings are common as muck here, go to an irrigation store, I can get fittings from 1/8 to 4 inch sch 40 steel.

Hell, home hardware sell them, it's a bigger outlet though.