PURPOSE: To exert corrosion preventing effect by automatically discharging only the ballast water in an oil tank from a drain nozzle and controlling the level of the ballast water within the oil tank to a specified range.
CONSTITUTION: This drainage system is composed of facilities for drainage composed of potential sensors 31 and 32 mounted on the inside face of an oil tank 1 by being insulated electrically, an earth electrode 4 mounted on the outside face of the oil tank 1, a potential detector 6 electrically connected with the potential sensors 31 and 32, and the earth electrode 4, respectively and separately, a relay circuit 7 and switches 8, 8' operated by the detection value of the potential detector 6, a drain nozzle 2, a drain nozzle piping arrangement 2', driving control parts 9 and 9', a drain pump 10 and a valve 11, etc.
AKUTSU MITSUO
IKEDA KENICHI
