Patent ID: 7536900

Claim:
A leak detector for detecting leakage of liquid stored in a tank based on fluctuation in a level of the liquid, the tank including a top plate, a bottom plate, and a side plate connecting the top plate and the bottom plate, the leak detector comprising: a flow-rate measuring portion, provided near a bottom end of the leak detector, for measuring a flow rate between liquid in the tank and liquid retained within the leak detector; a bottom attaching portion provided at the bottom end of the leak detector to detachably attach the bottom end to the bottom plate; a top assembly, attached to the top plate so as to cover an opening provided in the top plate and having a through opening through which an upper end of the leak detector is supported in such a manner that the upper end of the leak detector is simultaneously movable relatively to the top plate in a direction substantially perpendicular to a surface of the liquid while the bottom end of the leak detector is detachably attached to the bottom plate; a liquid inlet/outlet portion near the bottom end through which the liquid flows in and out of the leak detector; a flow-rate measuring unit arranged near the liquid inlet/outlet portion inside the leak detector toward the upper end, and configured to measure an amount of flow of the liquid occurring through the liquid inlet/outlet portion; and a liquid retaining portion arranged between the upper end and the flow-rate measuring unit, and including a space configured to retain liquid that has flown therein through the liquid inlet/outlet portion; wherein the flow-rate measuring unit includes: a flow path capillary through which liquid flows between the space and the liquid inlet/outlet portion; at least one temperature detecting unit configured to detect temperature of liquid inside the flow path; a heating unit configured to heat the liquid inside the flow path capillary; and a controlling unit configured to control heating temperature of the heating unit for heating the liquid inside the flow path capillary so that the temperature of liquid inside the liquid retaining portion and the temperature of the liquid inside the flow path capillary become substantially equal.