Method of measuring and indicating fluid levels

Abstract

A method for measuring the level or volume of a fluid within a fluid storage vessel which comprises: providing a multi-capacitor fluid level sensor formed of a pair of capacitors of fixed and substantially like capacitive value and two capacitors having like open dielectric spaces for receiving varying levels of the fluid within the vessel and with the fluid in the spaces consisting of a pair of capacitors of variable capacitive value; connecting the four capacitors of the sensor together to form the four capacitive sides of a Wheatstone bridge circuit; applying a source of alternating current of constant voltage and set frequency across the bridge circuit to a first set of bridge terminals at opposite corners of the bridge, each of such terminals located between a fixed capacitor and a variable capacitor of the sensor; interrogating the bridge circuit through a detection circuit connected across the bridge to a second set of bridge terminals independent of said first set of terminals and at opposite corners of the bridge, each of such terminals located between a fixed capacitor and a variable capacitor of the sensor; and measuring the current value in the detection circuit and indicating the value as a fluid level or fluid volume in direct linear relationship with the current value. The method may be used for volume measurement with respect to a wide variety of multi-component systems as long as the dielectric constants for the two or more components are different.