The Residual Chlorine Sensor is a specialized device crucial for maintaining water safety. It operates on the amperometric or colorimetric principle. In amperometric sensors, a small electric current is generated when residual chlorine in the water sample reacts with the sensor's electrodes. Colorimetric sensors, on the other hand, rely on a chemical reaction that changes the color of a reagent in proportion to the chlorine concentration, which is then optically measured. This chlorine residual sensor is widely used in water treatment plants, swimming pools, and the food and beverage industry. In water treatment, it ensures that the right amount of chlorine is present to disinfect water effectively while preventing over - chlorination. Its high sensitivity allows for the detection of even minute amounts of residual chlorine, typically in the range of parts per million (ppm). With quick response times, it can provide real - time data, enabling immediate adjustments to chlorine dosing systems.