Pneumatic Valves are an important and integral part of any pneumatic circuit. They are generally used to open, close or divert a compressed air flow path. They are available with three positions so that they can perform a different required function in their center or neutral position. Actuation of these pneumatic valves can be via a manual/mechanical method, electricity or air (single or double solenoid/air pilot). Pneumatic proportional valves operate such that a variable electric or air signal will open and close the valve proportionally to that input voltage or pressure.