3 way valve Roller type air pressure issues

[Kavi]

Hello,
I want to build a pneumatic airsoft rifle so I chose the easy way first. Got myself a qev and a roller type 3 way valve(In my mind this is the one that looks like a real trigger ) Have fabricated a chamber I tested the setup at 2 bars and every thing works great,the qev fires properly.

The problem starts to appear when I up the pressure, at 4 bars a lot of air is lost through the pilot port of the valve. I am not sure if my connections are correct,input goes to port labelled R and output is labelled A. The P port remains free. Am i doing something wrong?

I have been searching for a while now and I can't figure it out. Are my connections wrong(Any other way doesn't work) or is the valve malfunctioning?

I haven't even found a barrel yet as nothing much can be sourced locally, I have to buy everything from overseas. If the problem is not clear to you guys I can make a video and upload it to youtube.

I have noticed on one of the Wyz's video where he uses a push-pull valve that there is a silencer on one of the ports,will that be of any help to me?

I have included an Ebay link to the valve am using.

http://www.ebay.com/itm/181740711267?_t ... EBIDX%3AIT

Thanks very much for any replies and help.

[Ragnarok]

It sounds like you've got everything right, but I can't find a full spec-sheet for the valve, so I'm not absolutely certain.

I have noticed on one of the Wyz's video where he uses a push-pull valve that there is a silencer on one of the ports,will that be of any help to me?

It shouldn't make a difference, no.

[Kavi]

Thank you for the reply.

Am gonna disassemble the valve today to check.

I also have have an Airtac push-pull valve which I haven't tested yet,gonna see if it does the same thing.

[POLAND_SPUD]

Edit
Checked the diagram on the net (http://www.aliexpress.com/item-img/SNS- ... 59576.html#). The description on ebay was wrong or I understood it incorrectly - it's a normally closed valve:

How you should arrange it:
R = air source
A = the qev
P = for you it's the exhaust port of the pilot valve - keep it open and free from flow obstructions

and no adding a muffler won't improve performance, just the opposite.

My suggestion - try to wire it as as an NC valve. So you press the button / actuate the valve to fill the chamber and it fires/pilots when you release it. In that case:
P is the source
A is the qev
R is the exhaust

See if it results in improvement. You could use that configuration with a mechanical trigger mechanism that keeps the valve actuated when the trigger is in NOT PULLED state.

[Kavi]

Thanks for the reply.

The first way is the one am currently using which works for 2 bars or less.

I have tested the second way by swapping input/output around all ports and it works just like you described,pull to charge chamber and release to fire. This way works for up to 8 bars.

I tested the push-pull valve with a spring mod and for now I guess this is somewhat better.

Since this thread is already open can I ask a few more questions here?

If I connect a constant supply (shop compressor) to my chamber through a quick connector and then use a blow gun valve to the pilot port,will this be a good idea?

As I understand the qev works through pressure differential so by decreasing the pressure behind the rubber gasket it should fire.

Am sorry if sometimes I use the wrong words,my thoughts are in French so everything I type has been mentally translated and sometimes the words don't match.