Patent ID: 7334455

Claim:
A leak detector of liquid in a tank, comprising: a measuring slim-tube into/from which the liquid in the tank is introduced or discharged through the lower end thereof; a measuring tube connected to the upper end of the measuring slim-tube and having a sectional area larger than that thereof; a sensor section additionally provided to the measuring slim-tube and including a first temperature sensor, a heater and a second temperature sensor arranged in this order along the measuring slim-tube, the sensor section measuring the flow rate of the liquid in the measuring slim-tube; and a leak detection control unit connected to the sensor section, wherein the leak detection control unit has a pulse voltage generating circuit for applying a single pulse voltage to the heater and a leak detecting circuit connected to the first and second temperature sensors and generating an output corresponding to a difference between temperatures detected by the first and second temperature sensors, and wherein the leak detection control unit integrates a difference between an output of the leak detecting circuit and its initial value in response to the application of the single pulse voltage to the heater which is performed by the pulse voltage generating circuit to calculate a value equivalent to the flow rate of the liquid to thereby detect leakage of the liquid in the tank based on the calculated value.