The SY5100-X310 is a single solenoid valve for controlling the pilot air supply to the downstream valves within its zone. De-energizing the SY-X310 renders the downstream valves inoperable in response to a safe fault or for maintenance purposes. The return spring assures the return of the valve to the safe state when de-energized without requiring pilot pressure. The 5000 series was used as it can be added to a 7000 series manifold or have 3000 series valves added to a 5000 manifold.