摘要 |
A method and apparatus for detecting a change in the liquid level in a liquid storage tank, such as an underground hydrocarbon storage tank. A gas line is inserted just below the level of the liquid in the tank, and a second interconnected gas line is placed in a small liquid cup located on the surface. The differential pressure between the two lines is measured and used to compute the level in the tank. A second measurement taken hours later reveals any change in level indicating a leak. Provision is made to accurately zero the apparatus at each measurement to insure precision.
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