Indirect operated solenoid valves need a pressure differential over the inlet and outlet port for
operation. If the pressure differential is too low (f.e. a gravity fed system or a closed circuit),
(semi-)direct operated solenoid valves can be used. These operate from a zero bar pressure
3-Way Solenoid Valve (orifice <3mm):For small flow rate, such as actuation of a
(small) fuel system, a test setup, etc. 3-Weg Electric Ball Valve (bore >8mm):For
flow rates, such as central heating, irrigation, compressed air etc.