Float Level Sensors
Floats work on the simple principle of placing a buoyant object with a specific gravity intermediate between those of the process fluid and the headspace vapor into the tank,
then attaching a mechanical device to read out its position. Early float systems used mechanical components such as cables, tapes, pulleys, and gears to communicate level, whereas today, magnet-equipped floats are popular.
For both magnetic and mechanical float level sensors, chemical compatibility, temperature, specific gravity (density), buoyancy, and viscosity affect the selection of the stem and the float. Float sensors operate well in a wide variety of liquids,
including corrosives. A special application of float type sensors is the determination of interface level in oil-water separation systems. All in all, magnetic float switches are popular for simplicity, dependability and low cost.