The CDA330 features a plug and play design that incorporates a flow control device, a chlorine dioxide sensor, optional pH sensor and the LXT330 controller conveniently mounted on a PVC panel. Connect the sample and drain lines, connect the power and outputs and it is ready to use. Factory calibrated, calibration is accomplished by DPD comparison. Chlorine Dioxide (ClO2) exists as a gas in solution, it does not dissolved like other chlorine compounds and is therefore not affected by the pH of the solution. ClO2 is approximately 10 times more soluble than chlorine in water but it is extremely volatile and can be easily removed from dilute aqueous solutions with minimal aeration. Chlorine Dioxide diffuses through the PTFE membrane of the sensor and is reduced to chloride ion by the addition of electrons from the cathode. Silver from the anode is then oxidized to silver chloride. The electrons released from the gold cathode and the electrons accepted on the silver anode result in a current flow which is proportional to the chlorine dioxide concentration in the medium.
Temperature affects the ClO2 permeability of the PTFE membrane, increasing the temperature increases the output of the sensor about 4% per C°. The chlorine flow cell includes a temperature sensor that allows the LXT330 controller to perform automatic temperature compensation of the measurement. The CDA330 is 110-240 VAC or 24 VDC powered and allows either parameter to be graphically displayed with user defined Line, Bar or Gauge style graphs. The standard configuration has (2) 4-20 mA outputs, (3) alarm relays and MODBUS RTU.
Amperometric chlorine sensors are flow sensitive, the minimum required flow by the sensor is 0.5 ft/sec, above this value the output is virtually flow independent. A “Constant head” Flow control Device (CFD) maintains the optimum flow past the sensor over a wide range of incoming sample flow rates. The minimum flow required for the CFD is 10 gal/hr and the maximum flow is 80 gal/hr with the sample going to drain at atmospheric pressure. The Auto Clean option includes a solenoid acuated spray cleaner that uses either 30 psi process water or air. An easily adjusted timer controls the period and duration of the cleaning cycle.
