Hydrostatic pressure
A fluid column generates a specific hydrostatic pressure as a function of density and filling level.
A pressure sensor attached to the bottom of a tank measures this pressure with respect to a reference pressure (generally ambient pressure). Conclusions are then drawn as to the filling level with the aid of the known fluid density. Hydrostatic level measurement is suitable for virtually all types of fluids and produces very precise measured values, dependent on the accuracy of the pressure transmitter.
Installation example: hydrostatic pressure