Tankers shall be provided with an effective oil/water interface detectors approved by the Administration. And this device shall be provided for a rapid and accurate determination of the oil/water interface in slop tanks and shall be available for use in other tanks where the separation of oil and water is effected and from which it is intended to discharge effluent direct to the sea. This device should be tested according to the IMO Resolution MEPC 5, (XIII) for the prevention of pollution from ships.

Detection of Ullage
The detection method is based upon the principle of detecting a change in impedance using ultra sonic technology.
Detection of interface
The detection method is based upon measuring the different voltage according to conductivity of water.
Temperature measurement 
Temperature measurement is obtained by the output voltage of the built-in semiconductor element.