What does a air valve solenoid do?

Pneumatic solenoid valves are electromechanical devices that control the flow of air or process gas. They are mostly used for controlling pneumatic actuators such as cylinders, turbines (pneumatic motors), diaphragms, and tubes. Pneumatic solenoid valves and actuators form auxiliary air circuits.

Are solenoid valves normally open or closed?

One commonly used solenoid valve is one that is normally open. This valve works slightly different than a valve that is normally closed. The basic function of the normally open solenoid valve is the same. A normally open solenoid valve controls the flow of gas or liquid.