... ,(2) Double-Control Solenoid Valve ,(3) Voltage ,(4) Explosion-Proof Type3). Feedback Signal , (1) Mechanical Switches ,(2) Approachable ... Switches, (3) Output Current Signal ,(4) Voltage ,(5) Explosion-Proof Type4) Locator: (1) Electric Locator, (2) Pneumatic Locator, ... 4) Air Pressure Signal ,(5) Electrical Converter,(6) Explosion-Proof Type5). Air Source Treatment Triple- Unit (1 )Filter ...