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.

Abstract: A liquid level gauge for monitoring the height of liquid in a storage tank or the like. The gauge comprises an upright conducting probe adapted to be immersed in the liquid in the tank, and an upright series of electrodes closely adjacent the probe. The latter is adapted to be excited from a source of a.c. voltage generated by an astable multivibrator. Each of the electrodes is connected to the input of an amplifier through a rectifier circuit. The amplifiers are of the digital comparator type and have output terminals respectively connected by means of summing resistors to an electrical indicator such as a milliammeter, which provides an indication of the number of amplifiers being driven to full output at any particular time. The arrangement is such that each of the electrodes constitutes one plate of a capacitor, the other plate being formed by the single upright conducting probe. When a particular electrode is above the level of fluid in the tank, the magnitude of the a.c.