The system incorporates a valve closing mechanism comprising a control panel, a number of air driven motors, a corresponding number of air filter regulator lubricators, and a corresponding number of telescopic propeller shafts.
The telescopic propeller shaft transmits the torque and rotation from the drive air motor to the drum valve. The propeller shaft has an integral drive dog mechanism. When the drive dog is in the locked position it transmits the torque and rotation along the shaft effecting valve closure. When the drive dog is in the unlocked position it enables the two ends of the shaft to be rotated independently. This allows easy connection and disconnection of the shaft; a means of releasing the torsion in the shaft when a drum valve has been driven closed; and manual re-opening of the drum valve.
Air powered motors are supplied with air under pressure via a compressor and a receiver. The compressor provides a constant, predetermined pressure between 20-25 psig sufficient to rotate the shaft assembly through as many revolutions as necessary to drive the handwheel from an open position to a fully closed position.
Operation of the mechanism to close the valve may be triggered by the chlorine in air sensor within the enclosure housing the drum and/or it may be initiated manually by means of a user operable button located remotely from the storage vessels and/or chlorine detector. A further closing actuation can be achieved manually from the control panel.
...either by an operative (who will press the button) and/or by the detector, the system operates to rotate the handwheels and close the drum valves. In these circumstances, the pressure control valve is opened so that the air motors are operated to rotate the shaft assemblies, via the coupling devices, in the valve closing direction. The receiver is designed and arranged so that there is sufficient air pressure available at all times to operate the air motors, to the extent necessary to effect complete closure of all of the drum valves