LEAKAGE INSPECTING METHOD OF TANK

PURPOSE:To inspect quickly a leakage of an underground tank in a state that a liquid is stored without moving the liquid in the tank by mixing a inert gas for pressure reducing, and exhausting a gas in the tank. CONSTITUTION:When openings of an oiling pipe 3 and a vent pipe 8 are closed by covers 4, 9, and also a measuring port 10 is closed by a plug 12, an underground tank 1 is closed airtightly. Subsequently, when nitrogen gas of a bomb 28 is supplied to an ejector 21 by opening manual valves 25, 28 and 30, a gas such as a gasoline vapor, etc. in the tank 1 is absorbed by the ejector 21 and exhausted through a silencer 27 together with the nitrogen gas, and the inside of the tank 1 is reduced to a prescribed pressure. In this state, when a leakage hole 31, etc. exist in the tank 1, an external air is absorbed and rises in a liquid, a suction sound such as a hollow sound, etc. is generated, this suction sound is detected through a microphone 19, etc., and a leakage of the underground tank can be detected quickly in a state that the liquid is stored without moving the liquid in the tank.