Externally- and force pilot operated Valve. Valve closed by spring force in rest position - NC. When the actuator (cylinder) is pressurised the piston (spindle) is lifted of the pilot and main orifice and the valve will open directly or servo assisted by the pressure differential (delta p) of the flow medium. A pressure differential (delta p) is not required for the operation. Further functions like NO - by spring force in rest position or double acting actuators are also available.