Device for detecting leakage of liquid in tank

摘要

A device placed in a tank and used for detecting a leakage of liquid in the tank. Vertical measurement tube passages ( 10, 14 ) into which the liquid in the tank is introduced have a measurement tube ( 10 ) and a measurement thin tube ( 14 ). The measurement thin tube ( 14 ) communicates with the measurement tube and is located lower than the measurement tube. The measurement thin tube has a cross-sectional area that is equal to or smaller than {fraction (1/50 of that of the measurement tube. A thermal flow sensor ( 16 ) used for measuring a liquid flow rate is attached to the measurement thin tube ( 14 ). There is provided leakage detecting means ( 22 ) for detecting a leakage of liquid in the tank according to the flow rate value measured by the sensor. The leakage detecting means generates a leakage detection signal when a flow rate value measured by the sensor is within a range greater than 0 and smaller than the flow rate value obtained when liquid is added to the tank or when the liquid in the tank is taken out. Thus, even a leakage of a very small amount is detected easily and accurately without stopping the use of the tank.