초록 ▼

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 surf

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.

대표청구항 ▼

A method for detecting a change in the amount of liquid in a storage tank comprising the steps of: (a) providing a source of gas at greater than atmospheric pressure; (b) positioning a gas line communicating with said gas source in said storage tank, the end of said gas line being below the surface

A method for detecting a change in the amount of liquid in a storage tank comprising the steps of: (a) providing a source of gas at greater than atmospheric pressure; (b) positioning a gas line communicating with said gas source in said storage tank, the end of said gas line being below the surface of the liquid; (c) positioning a second gas line communicating with said gas source into a liquid filled cup, the end of said line being movable between a first position at the surface of the liquid and a second position below the surface; (d) sensing the differential pressure between said first and second gas lines and adjusting said second position of said second gas line until said differential pressure is zero; (e) computing the depth of the end of said first line from the observed depth of the end of said second line; (f) holding said first gas line in fixed position for a predetermined time; and (g) re-zeroing the differential pressure between said first and second lines after said predetermined time by repositioning the end of said second line and recalculating the depth of said first gas line.