Abstract: A system for filing or discharging compressed gas or liquid cylinders mounted on the cylinder. An automatic system for filing or discharging a compressed gas cylinder, specifically chlorine, sulfur dioxide, or ammonia cylinders. The system includes an electric motor that rotates the cylinder valve system toward open or closed position without interfering with or requiring additional adapters for the filing or discharge hardware. The motor, gears, and controls are assembled as one unit to eliminate the necessity for a separate control panel or interconnecting control wires. The system has the capabilities for integral leak detection with automatic shutdown, battery backup in the event of power failure, remote control by leak detector, remote control panic button, remote low weight transmitter, remote vacuum switch for automatic switch-over systems and other remote digital signals.