Abstract

A gauging apparatus for monitoring the height or level of liquid contained in a storage tank or the like. The apparatus comprises a probe device in the form of an elongate piece of insulating material carrying a first plurality of spaced-apart conducting members disposed along the length thereof, and a second plurality of conducting members disposed adjacent the members of the first plurality and forming multiple capacitors therewith, respectively. The insulating material, as well as the members carried thereby, are covered by a coating of insulating resin such that they are sealed against physical contact with the liquid being monitored. Detector means including amplifiers and indicators are provided for sensing which members of the first plurality are submerged in liquid at any particular time. The detector means responds to changes in the dielectric of the capacitors as they successively become submerged to provide indications of the liquid level in the tank. In an alternate embodiment of the invention, two detector means are provided, one of which responds only to liquids having a relatively high dielectric constant, such as salt water or the like. The arrangement is such that in the case of a tank partially filled with oil and partially filled with salt water, there are obtained indications of the total quantity of liquid in the tank, as well as the relative proportion of the liquid having the higher dielectric constant, in this case, salt water. The difference between these readings yields the amount of oil remaining in the tank.