FREE-VALVE Normally Closed Pneumatic Operated Fluorine Lined Diaphragm Valve is composed of single-acting pneumatic actuator and diaphragm valve, which uses pneumatic actuator to drive the opening and closing of the diaphragm valve, and the valve is kept in normally close state in the case of no air source or no signal, and the valve is in a opened state after the cylinder is ventilated, so as to act as an opening and closing mechanism to control the flow of medium.