Patent ID: 8286483

Claim:
A method of determining a thickness and a depth of a layer of a liquid of a first phase that is floating on a layer of a liquid of a different second phase, comprising the actions of: a. detecting a first depth of a portion of a pressure sensor that is placed in the liquid of the second phase by measuring a length of cable, connected to and supporting the sensor, played out until the sensor reaches the first depth; b. sensing an apparent pressure sensed by the pressure sensor at the first depth; c. detecting a first distance from the portion of the sensor to an interface between the liquid of the first phase and the liquid of the second phase; and d. calculating the thickness of the layer of the liquid of the first phase that is equal to (the apparent pressure minus a specific gravity of the liquid of the second phase times the first distance times a pressure increase per unit depth of the liquid of the first phase) divided by a pressure increase per unit depth of the liquid of the first phase.