Rosemount Analytical - Model 499ACL

Model 499ACL Chlorine Sensor

MEASURE TOTAL or FREE CHLORINE or IODINE without sample pretreatment or messy & expensive reagents
EASILY REPLACEABLE MEMBRANE, no special tools required
AUTOMATIC CORRECTION to pH 9.5
AUTOMATIC COMPENSATION for changes in membrane permeability with temperature
AUTOMATIC PRESSURE EQUALIZATION to maintain correct membrane tension
COMPATIBLE with most Delta and Rosemount Analytical Analyzers
VARIOPOL CONNECTOR OPTION allows the sensor to be replaced without new cable

FEATURES AND APPLICATIONS

MODEL 499ACL-01 FREE RESIDUAL CHLORINE SENSOR
The 499ACL-01 is intended for the continuous determination of free chlorine (hypochlorous acid plus hypochlorite ion) in water. The primary application is measuring chlorine levels in drinking water. It can also be used to monitor dechlorination processes. The sensor requires no acid pretreatment and can measure free chlorine in samples having pH as high as 9.5. The linear range of the sensor is 0 to 10 ppm. For determination of higher levels of chlorine, consult the factory.

The 499ACL-01 is a membrane-covered amperometric sensor, consisting of a proprietary porous membrane stretched tightly over a platinum cathode. A silver anode and an electrolyte solution complete the internal circuit. During operation, free chlorine diffuses from the sample through the membrane. A polarizing voltage applied to the cathode completely reduces free chlorine to chloride ion. The reduction produces a current between the cathode and the anode, which the analyzer measures. The current is directly proportional to the rate at which free chlorine diffuses through the membrane, which is ultimately proportional to the concentration of free chlorine in the sample.

MODEL 499ACL-02 TOTAL CHLORINE SENSOR
The 499ACL-02 is used with the Model 1055-24 analyzer in the TCL sample conditioning system. Although the sensor is called a total chlorine sensor, it really measures iodine. The iodine comes from the reaction between total chlorine in the sample and the buffered potassium iodide reagent added by the sample conditioning system.

The 499ACL-02 consists of a gold cathode and a silver anode in an electrolyte solution. A silicone membrane, permeable to iodine, is stretched over the cathode. The analyzer applies a voltage to the cathode sufficiently negative to reduce all the iodine reaching it. Because the concentration of iodine in the sensor is zero, a concentration gradient continuously forces iodine from the sample through the membrane into the sensor.

The reduction of iodine in the sensor generates a current directly proportional to the concentration of iodine in the sample. Because the iodine depends on the amount of total chlorine in the sample, the sensor current is ultimately proportional to the total chlorine concentration.

The permeability of the membrane to iodine is a function of temperature. A Pt100 RTD in the sensor measures the temperature, and the analyzer uses the temperature to compensate the total chlorine reading for changes in membrane permbeability.

MODEL 499ACL-03 MONOCHLORAMINE SENSOR
The Model 499ACL-03 sensor is intended for the determination of monochloramine in drinking water and wastewater. The Model 499ACL-03 is a membrane-covered amperometric sensor. The sensor consists of a PTFE membrane stretched tightly over a gold mesh cathode. A silver anode and electrolyte solution complete the internal circuit. During operation, monochloramine diffuses through the membrane. Once inside the sensor, monochloramine reacts with the fill solution to produce an intermediate compound. A polarizing voltage applied to the cathode completely reduces the intermediate. The reaction produces a current, which the analyzer measures. The current is directly proportional to the rate at which monochloramine diffuses through the membrane, which is ultimately proportional to the concentration of monochloramine in the sample.

Maintenance is fast and easy. Replacing the membrane requires no special tools or fixtures. Simply place a few drops of electrolyte solution in the membrane assembly, place it over the cathode, and screw the retainer in place. To replenish the electrolyte solution, unscrew the fill plug, add the reagent from a squeeze bottle, and replace the plug.