What did i just buy?

[Alex345]

I found this BIG valve(ish) thing at a local tool shop in one of it's many miscellaneous boxes. To me it looked like a huge piston valve, but i have been deceived in ways like that a few times before... But since they sold it for dirt cheap i took a chance and bought it!

I just took some photo's, one where it is compared with a normal 3/4 qev and also a few shots of it taken apart. Enjoy;

[Labtecpower]

Looks like some kind of diaphragm valve to me, judging by the holes in the top and side it is pressure controlled.

Could you unscrew the top cap?

[MRR]

According to google, PSV stands for Pressure Safty Valve. The picture search revealed a similar design to this one.

It looks like (could be wrong though) that you can screw in a little pressure release valve which triggers the PSV.

[jackssmirkingrevenge]

That must have cost a lot new, nice catch if you got it for peanuts. Agreed with lab, looks like an exhaust valve.

[Alex345]

That must have cost a lot new, nice catch if you got it for peanuts. Agreed with lab, looks like an exhaust valve.

When i got to the cash register i prepared myself for one heck of a price! But then the lady picked it up, put it on a scale to weigh how much brass it was and charged me 10€

I really had to force myself not to start smiling like an idiot XD

Here are some more pictures for Labtecpower without the cap and with the "piston" open and closed:

[Labtecpower]

With a fancy PTFE sealing face, i'd guess the price is in the three digit range

Can't tell how the piloting system works from the pics, I guess the best option is to hook it up to an air source and do some tests hehe

[Brian the brain]

Plug the hole on the side, and insert a pilotvalve on top..

Then its a pistonvalve.

[Alex345]

Plug the hole on the side, and insert a pilotvalve on top..

Then its a pistonvalve.

Already plugged it Just need to find a cheap pilot valve with 1/8 threads. Right now the only issue is the fact that the threads on both sides of the valve are massive! The biggest thread size most hardware stores have is 1" so i'll have to look at specialized stores for the right pieces. This thing is truly huge and the pictures simply don't do it justice. A lot of you spudding veterans have probably seen way bigger ones, but for me this is quite a sight

I'm getting more excited by the minute! I can't wait to test this thing

[Gippeto]

Good score. 8)

[Alex345]

Ok this is a strange valve :p Apparently you CANT plug the hole on the side because doing so creates a vacuum preventing the piston from moving smoothly.

I will try to draw something up for you guys

[Alex345]

Ok here we go So now i know that the valve will only function when you leave the extra hole on the side alone, so no problem there. But i would really like to know what it is for

[dewey-1]

Ok here we go So now i know that the valve will only function when you leave the extra hole on the side alone, so no problem there. But i would really like to know what it is for

Here is what I think it is;
http://www.eng-tips.com/faqs.cfm?fid=744

Is there any company logo or symbol on it?

I can see: PSV-D 40/40 C ???

[Alex345]

Yes PSV-D 40/40 C and PTFE on the other side, which would refer to the sealing face. On the bottom there is CW617N which is apparently the type of brass it is made from. And an arrow pointing to the exhaust side with IB next to it.

And that's all she wrote i'm afraid :p You'd think someone would put a brand name on something that big and probably expensive...

[MrCrowley]

I'm jealous. That's one cool valve, hope to see it on a ~200PSI cannon in the near future

Ok this is a strange valve :p Apparently you CANT plug the hole on the side because doing so creates a vacuum preventing the piston from moving smoothly

I guess because it is all o-ringed and what not, actuating the piston would decrease the (atmospheric) pressure in that middle bit if you blocked the hole, thus creating a small vacuum. If that is indeed what happens, just leave the hole open and don't worry about it as no chamber or pilot pressure should reach that middle area.

I'd recommend hooking up the fill line to both the chamber and pilot but with a ball valve to close off the chamber from the pilot when it comes to firing the cannon. Basically means you have a safety valve on the cannon too since triggering the pilot valve probably wont actuate the piston valve if the chamber line is still hooked up to the pilot.

[Brian the brain]

ah...



you'll need to loop the pilot into the middlesection for it to pop open ..
Or..take out the bottom center O-ring and THEN plug the side.