Patent ID: 7275430
Filing Date: 2007-10-02
Classification: G01F

Abstract:
1. A method for repeatedly detecting the respective liquid level in each of a plurality of containers containing liquids of different bulk electrical resistivities, said method comprising the steps of: (a) positioning a pair of spaced electrodes within each of said containers; (b) selectively polling each of said pairs of electrodes by applying a pulsed electrical signal between said selected pairs of electrodes; (c) monitoring the voltage between each of said selected electrode pairs while said electrode pairs are polled; (d) determining the liquid-level in each of said containers on the basis of a predetermined change in voltage across said selected electrode pairs, as caused by a liquid within the respective containers physically bridging, or non-bridging, said electrode pairs as the liquid level changes within said containers; and (e) prior to polling each pair of electrodes in a container, adjusting the amplitude of said pulsed signal in accordance with the bulk electrical resistivity of the liquid within said container, whereby said predetermined change in voltage is normalized for all containers.