Patent ID: 7461550

Claim:
A fluid level sensing apparatus for placement in a container comprising: a capacitance sensor further comprising an electrically conductive first body having a first surface contact area, an electrically conductive second body having a second surface contact area disposed in opposition to the first body; an electromechanical sensor further comprising a guide positioned in a fluid to be measured disposed in the container, a float movably connected to the guide to rise and fall with a fluid level, a series of reed switches disposed at pre-selected intervals along the guide, and a means for establishing a magnetic field across the reed switches, a container progressively filled with the fluid in order to change the fluid level, wherein the fluid electrically couples a first fraction of the first surface contact area and a second fraction of the second surface contact area, and wherein the change in the fluid level changes the float position along the guide in order to move the means for establishing a magnetic field and close a reed switch associated with a pre-determined fluid level, a means for energizing the first body and the second body at a voltage; a means for detecting the variability in voltage as the fluid level in the container changes as the first fraction of the first surface contact area and the second fraction of the second surface contact area changes; and a means for determining which reed switch is closed as the fluid level in the container changes, wherein the determination of the fluid level based on the means for determining which reed switch is closed is used to correct the determination of the fluid level based on the means for detecting the variability of the voltage by fixing known level steps, wherein the circular vertical probe is covered by a polytetrafluoethylene insulation.