how could you make a valve or a system so that when it is pressurized, if enough pressure is reached in the system the valve will open completely and remain opened until it is close manually?I'm thinking about this in the context of an air powered dart gun, so that the firing mechanism is like a piston, and when a certain air pressure is reached, the valve that connects to the barrel will open and fire the dart
One thing you can do is get a pressure switch and a solenoid valve so that when whatever you are pressurizing comes to a certain level the switch will close it's normally open contacts and energize the solenoid which will open the valve. However as soon as the pressure level goes below the trigger level the valve will automatically close.
