SpudFiles

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.

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.

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.

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.

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.