FS-IR02 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.

Optical level sensor can be used in most electrical appliances.                  

The optical level sensor is installed at the bottom of the device (or any other location as long as it can achieve this function). 

When the water level in the device is lower than the sensor, the sensor will give a signal to indicate the lack of water, so the
device stops working and will automatically enter Water filling state; installed on the side, when the water is added to a certain position, the photoelectric liquid level sensor will also give a signal, so the device stops the water filling work to prevent the water from overflowing.

comparing with float switch; it’s not easy to get stuck and produce gutters, smooth and easy to clean, and has high accuracy and no mechanical parts.
In addition, the sensor can be customized according different requirements.