What kind of valve will do this?

[bdr16]

I need a valve that will pressurize a system, then leave the system pressurized for a time, then exhaust the pressure on command. I need it to be easily portable and quite small, and will run at pretty low pressures. What kind of valve would do this for me?

 

[darkside00]

A regular gate valve will work just fine. depends how small your pipe/tubing is. maybe just an instrument valve