SpudFiles

Hey all,

I'm gonna need to build a system with 75 mm caliber barrel of 3.5 m length. The installation space in a tank turret will be very limited, thus I cannot go with a huge and low pressure chamber. All will be steel-made. The expansion chamber is expected to be around 3-4 litres and hold up to 30 bar. I'm not shy of using solenoid valves, some are extremely quick in smaller sizes. But this setup will require 1" valve for sure, whose opening times tend to be higher. It may be still acceptable, but this is not guaranteed. Projectile is lightweight (say 45 gram, discarding sabot mass included) and the muzzle velocity is expected up to 70 meters per second.
What other fast valve alternatives (or combinations) with big enough orifice are there for medium pressures? Some example links would be appreciated as I will need to search for those locally and translation of valve-types from English may not be always totally accurate.

Thanks!

It is unusual to answer your own topic - top-quality solenoid valves are the only reasonable options. It depends on the length of a barrel whether two smaller but faster valves or one bigger and slower valve are alright.

Is a piston valve an option? That's what I'd go with, but you have to make it yourself.

It might be - but the labor associated with making a custom piston valve isn't worth it. I'll have enough work with the whole metal gun. And solenoid valve is able to push a lightweight projectile at reasonable speeds from 2L air reservoir even in this setup (around 70 m/s2 which for this tank gun equals ~ 180 m max distance. Good enough for paintball.

How about piloting a QEV with a smaller solenoid? That should provide a useful boost in performance without having to build your own valve.

Are QEVs available also to 30 bar?

Yeah, but they are pretty (read "very") expensive, especially in the sizes you're looking at. Expensive enough that it's maybe worth talking to a local machine shop.

great job though