Model 498CL pH-Independent Free Chlorine Sensor

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MEASURE FREE CHLORINE without sample treatment and without an auxiliary pH sensor SENSOR RESPONSE IS PRACTICALLY INDEPENDENT of pH between pH 6.5 and 10 AUTOMATIC CORRECTION for changes in membrane permeability caused by temperature EASILY REPLACED MEMBRANE; no special tools required VARIOPOL CONNECTOR OPTION allows the sensor to be replaced without running new cable

FEATURES AND APPLICATIONS The Model 498CL-01 sensor is intended for the continuous determination of free chlorine (hypochlorous acid plus hypochlorite ion) in water. The primary application is measuring chlorine in drinking water. The sensor can also be used to monitor dechlorination. The sensor requires no acid pre-treatment, nor is an auxiliary pH sensor required for pH correction. Between pH 6.5 and 10 the chlorine reading decreases less than 4% per unit increase in pH. Below pH 6.5 the change is less than 1%. The linear range of the sensor is 0 to 20 ppm. For determination of higher levels of chlorine, consult the factory. The 498CL-01 is a three electrode, membrane-covered amperometric sensor. The sensor consists of a hydrophilic membrane stretched over a gold mesh cathode. A silver/silver chloride reference electrode and a copper auxiliary electrode complete the circuit. The fill solution is saturated succinic acid. During operation, an electrochemical reaction, driven by the polarizing voltage, consumes free chlorine at the cathode surface. The auxiliary electrode provides the electrons for the cathode reaction, and a current proportional to the reaction rate flows between the electrodes. Because the concentration of chlorine at the cathode is zero, free chlorine in the sample continuously diffuses through the membrane to be destroyed at the cathode. Thus, the current is proportional to the diffusion rate, which is proportional to the concentration of free chlorine in the sample.