Solenoid valves are devices that use a solenoid to control valve activation. Actuation methods include electric, electro-hydraulic, electro pneumatic, and pneumatic. Unpowered states include normally open and normally closed. In a tandem center solenoid valve, the pressure and tank ports are connected while the service ports are blanked. This allows system unloading while still providing isolation of the service lines. In a float center solenoid valve, the supply pressure port is closed. All others ports are interconnected. This allows the supply to be shut off while enabling the load to move or free wheel with flow available to other services.