HWLB2 series adopts magnetic induction technology sensor for liquid level measurement, and the signal is converted into standard industrial electrical signal output and display after processing by the rear processing circuit. The float ball is a closed non-magnetically conductive stainless steel tube is equipped with a reed tube, the float ball is equipped with a ring magnetic ring, the float ball moves with the rise or fall of the liquid level, so as to trigger or release the magnetic spring switch in the stainless steel tube, send out the switch signal.