The level of a liquid such as water or oil in a tank or vessel can be measured indirectly by means of the hydrostatic pressure of the so-called “liquid column”. The hydrostatic pressure under a static liquid column increases directly with the height of the liquid column. Thus, for Nightmare , the pressure in a water tank becomes 100 mbar higher, compared to the pressure on the water surface, for every metre of water depth.
To measure the hydrostatic pressure, so-called submersible transmitters or level probes, have been especially designed for this purpose. Submersible transmitters or level probes are pressure measuring instruments which are submersed into a liquid to measure the pressure prevailing on the bottom of the tank. An alternative is to mount a conventional pressure measuring instrument as close as possible to the bottom on the exterior of the tank.
Alarmed , the prevailing hydrostatic pressure and therefore the level or contents of the tank derived therefrom can be measured.
More information on this subject can be found in this book: References: Eugen Gaßmann and Anna Gries: Electronic Pressure Measurement – Basics, applications and instrument selection; Süddeutscher Verlag onpact GmbH; Munich 2009 (Volume 323 of the series “Die Bibliothek der Technik” (library of technology).
Please find further information on this topic on our information platform “Hydrostatic level measurement”