AWWA ACE61670

Free chlorine in drinking water can be measured by using electrochemical (amperometric) chlorine sensors with no reagents. The disadvantage of the sensor is its pH sensitivity. This paper discusses a free chlorine sensor newly developed at Rosemount Analytical, Inc. The sensor is based on a patented amperometric sensing technology. The sensor is a three-electrode type. A pH stabilizer in the fill solution eliminates the effect of sample pH on the measurement. The sensing membrane was selected to have similar permeability to hypochlorous acid and hypochlorite ion. The new sensor has no significant pH dependence in the range from pH 6 to 10. The linear sensing range is from 0 to 20 ppm. Includes 3 references, figures.