The diaphragm between the actuator and valve body hermetically isolates the fluid from the actuator. The valves are maintenance-free and extremely robust and can be retrofitted with a comprehensive range of accessories, e.g. electrical position feedback, stroke limitation or manual override.
Figure shows unactuated and actuated position of diaphragm valves.
Figure : Diaphragm valve: unactuated position, actuated position
Closed position: When de-energized, the valve is closed by spring action
Open position: If the actuator is pressurized by the control pressure, it simultaneously lifts the control piston and the valve spindle to open the valve.