Force pilot operated valves operate from 0 bar and can be installed where directly acting valves are used. However, beyond the range of the latter, they are supplied with smaller solenoids for higher pressures and larger nominal sizes. The actuator of a force pilot operated valve opens a pilot orifice and then lifts the sealing element from its seat directly or supported by the delta p of the operating pressure.
The special feature of force pilot operated valves is that the actuator in the pressure range can open and close the valve without using the operating pressure. In the case of pressure differential, usually when opening the valve, the collective energy is used.
More information on force pilot-operated solenoid valves on GSR’s website.