FS-IR02B series Water Liquid Single Point Level Sensor, the theory is infrared, it can totally replace traditional float level switch, it controls the level though output high or low voltage. When the detected level is in air, due to reflect of the prism,most of light will enter receiver LED, optical level sensor will output high voltage. When the detected level is in water, due to refraction of the liquid, just less of light enter receiver LED, optical level sensor will output low voltage.
