Do I need a normally open or normally closed 2/3way valve?

[AlfiePB IanB]

Hi, I want to use a 2/3way valve to fill and then fire my qev based launcher, do I need a normally open or closed 2/3way valve?

Many thanks Ian

[matti]

I think you mean 3/2 ..And I think you need normally open (NO) valve. That way it fills your chamber in the normally open state and when you trigger the valve it vents the pilot air.

Hope this helps:
http://www.valve-university.com/communi ... image6.png

[AlfiePB IanB]

Ha ha that's probably why I was getting much luck searching!!! Thanks for the input.

Anyone got advice on a Clippard etc 3/2way valve as a I see some of the models are rated at higher than the regular 150psi/10bar. I was looking at the MJ-V3 but after contacting them found it to be normally closed, thanks.

Thanks for the picture of the symbolic representation of the valves, I was reading up on those, quite confusing, well for me!

[iknowmy3tables]

the thread is old but I wanted to share some knowledge if anyone searches this. you do need a normally open valve but many valves may not say. The most common is normally closed however some of these valves like this one http://www.ebay.com/itm/3-Way-Pneumatic ... 2285609406? are reversible where you can unscrew the ends remove the piston and reverse them so the valves changes from normally closed to normally open