PROBLEM TO BE SOLVED: To sense an oil by a float body irrespective of the existence of water. SOLUTION: In a cylindrical body 1 into which a liquid can flow, a first float body 2 which generates a buoyancy with reference to the water and which sinks with reference to the oil to be sensed and a second float body 3 which generates a buoyancy with reference to the oil and which is situated in the upper part of the first float body 2 are housed so as to be up and down movable, A sensor 17 which outputs a signal at a time when the first float body 2 and the second float body 3 are separated by a definite length is installed. At a stage at which the oil is stored on the surface of the water up to the thickness of the definite length, the first float body 2 and the second float body 3 are separated, and a signal is output from the sensor 17.
展开▼
