BMS is a bubbling system for level detection based on the measurement of hydrostatic pressure caused by the liquid contained in the tank.

The working principle is founded on the measure of the pressure value needed to maintain a constant and regular air flow through a pipe probe open in the bottom and submerged into the liquid. At any level variation of the liquid in the tank corresponds a variation of the hydrostatic pressure applied on the air outgoing from the probe pipe; these pressure variations are precisely detected by the 27M P/I converter and converted into a standard 4?20 mA electric signal.