Series 4 solenoid valves have been designed in the 3/2, 5/2, 5/3 versions and with the following two devices of actuation: - electropneumatically actuated with mechanical spring return - electropneumatically actuated and return with external and internal air pressure supply Series 4 valves are equipped with a manual override which allows a stable operation and they are particularly suitable for mounting in arduous conditions. All these valves can be operated by solenoids Series U, G A8 and H8. Pneumatically actuated valves 3/2 NC become NO when the supply is on connection 3.