Solenoid Problems

[BramR]

Hi guys! :albino:

After using a spring return 3-way-2-position valve for a while to pilot my QEV, I decided to order a solenoid valve. It came in yesterday and I immediately tried to install it. It was my first time messing around with wires and all..... but I'm pretty sure I installed it correctly. I run a simple QEV with chamber and as mentioned previously a solenoid valve setup, this is shown below:

Now here is the problem:

When I attach the air supply to port R, I hear a light sissing noise which indicates there is some kind of leakage. Then when I press the button to power the valve, I hear the coil doing its job but it does not switch ports. I suspect that is has something to do with pressure difference.

I was pretty sure that I had to attach the air supply to port R. To make sure I wasn't doing it wrong I attached the air supply to port P to test it. At port P, I still hear a light sissing noise. But now when the button is pressed you hear the chamber of the QEV filling up (which makes sense when you look at the schematics). Then when i release the button, air is released from port R and the QEV pops. Of course this is the desired effect but that would mean that i constantly have to power the solenoid. and it still doesn't solve the problem for the leakage at the valve.

I have no idea what i am doing wrong, but i think it has something to do with the lack of pressure at the ''unused'' port.

I hope someone has encountered the same problem before and that he/she can help me!!!

With kind regards,

BramR, The Netherlands

[matti]

Hi, port P is for filling. But sounds like you have NC valve (normally closed) and that means your chamber will only fill when solenoid is powered. For use like that you should have NO (normally open) valve that fills your chamber when solenoid is not powered and closes the P port when powered. Leaking sound is probably from leaking valve

[BramR]

But why does it matter whether I use the P or the R port? Or is ot because i dont fully understand how this valve is working?:)

[matti]

But why does it matter whether I use the P or the R port? Or is ot because i dont fully understand how this valve is working?:)

Many solenoid valves in pneumatics take air from the port where air should be connected, in this case port P. Pressure in that port is used to open the valve and the black thing on top of the aluminum case is probably the pilot valve system. Thats why they have different valves for vacuum use and also for low pressure use. If it would be direct acting valve that uses only solenoid to open valve then you probably could use other ports but not in this case I believe.

Can you post the valve model number or a diagram of it that also shows the solenoid part. That way I could check how the valve actually works.

[BramR]

Here is a picture from closer by.

solenoid.jpg (31.68 KiB) Viewed 5420 times

[matti]

Here is a picture from closer by.

The attachment solenoid.jpg is no longer available

Yeap, thats a pilot operated valve. So to use it you need a constant pressure at port P. Thats the same reason the valve says 0.15-0.8MPa pressure and not 0-0.8MPA

Because it's NC/normally closed valve it's dangerous to use it with qev since if you lose power from low battery or bad connection etc. it will shoot

BUT You still might have a way to make it work, check this (scroll down the page)
https://www.frightprops.com/faq/content ... ation.html


AND for later help if you buy more valves..
Heres a valve diagram to show the difference of NO and NC valve in their diagrams: http://solenoidvalveshop.co.uk/img/arti ... nction.gif

3way-circuit-function.gif (7.27 KiB) Viewed 5415 times

[BramR]

Thanks man, I really appreciate your help! that article really helped. It was easy to switch the piston around. I changed to a NO solenoid valve.

But....... it is still leaking out of the R port when it is at rest. the leaking sound disappers when I activate the valve. which is exactly the same as when it was a NC valve. I opened it up again and checked if maybe there was some teflon tape in the valve which prevented it from being airtight, but there was none. i really dont know why it is leaking. Is it maybe because it needs a minimum pressure of 0.15 MPa at the R port?

[matti]

i really dont know why it is leaking. Is it maybe because it needs a minimum pressure of 0.15 MPa at the R port?

At the end of the instructions it says: Please note that the "P" (the port that air from the compressor goes into) will now be changed to the one that is closest to the solenoid and not the one marked "P".

Did you notice that? Test if it makes any difference.

[BramR]

If i attach the air supply to the R port it still does not work. I believe it is because the piston isnt fully symmetrical. Also inside of the valve there is a small hole, i believe that it is there to pilot the valve because it connects with the hole(s) in the side of the valve that connect to the "electric" part of the valve. Maybe this solenoid valve is just not suited to be made into a NO valve. I think i have to order a new one.

I really want to thank you for your help with all of this, even though it still does not work I learned alot from (dis)assembling everything .

[matti]

I really want to thank you for your help with all of this, even though it still does not work I learned alot from (dis)assembling everything .

No problem 8) hope you get a new valve and get things working!

[BramR]

Just to make sure i wont make the same mistake again:D

When i buy this 5/2 solenoid valve, i basically cant do it wrong as long as i seal one of the ports so the air supply wont leak out?

http://www.ebay.com/itm/1x-4V210-08-5Po ... ilOZYWy1rg

Its an 5/2 solenoid because for some reason it is cheaper than a 3/2 only 8,55 dollars:D

[matti]

That should work OK ! It's very cheap valve so not sure what the quality of those are. I have used some Herion 4/2 valves that are over 10 years old and they work perfectly still, but they are qood quality ones rated for many millions of cycles.