Water drainage system

摘要

An oil tank 1 has a system for automatically draining accumulated water comprising a closed circuit round which pump 5 circulates liquid from near the tank floor through detector tube 7, which encloses two independent monitors 8 able to detect variations in the proportions of oil and water to enable logic unit 9 to open and close discharge valve 10. Valve 10 is opened only if both monitors indicate a given proportion of water in the mixture being circulated, but a signal from one monitor only is enough to close the valve. If the monitors continue to give different signals however an alarm operates. Pump 5 operates intermittently under timer control, and the system may service several tanks in turn (Fig. 5). Valve 10 may be combined with pressure-maintaining valve 12 (Fig. 3) or replaced by a large-bore valve (60) connected upstream of pump 5 to discharge water under gravity (Fig. 6).