... OverviewAW pneumatlc actuators are divided to double-acting and single-acting (spring return ) with two separated cylinders and ... off or failure (Explosion-prool offer available) Single-control solenoid valve: Valve opens or closes when power on , vice ... ) Double-Acting ,(2) Single-Acting ,(3) Model2). Solenoid Valve, (1) Single-Control Solenoid Valve ,(2) Double-Control Solenoid Valve ,(3) Voltage ,(4) ...