The amperometric sensor can also measure total residual chlorine levels up to 20 ppm. A magnetically coupled pump in the sensor tip provides a fixed constant flow across the electrodes. All amperometric sensors are flow sensitive. Generating consistent velocity, sensitivity, and signal-to-noise ratio is better for lower TRO detection levels. The integrated pump uses a Brushless DC motor. The impeller is made from an engineered polymer formulation, creating low friction and long life.