Model CDA330​​​

Chlorine Dioxide Analyzer​​​​​​​


The CDA330 is a panel mounted, ready to use Chlorine Dioxide Analyzer. It is designed to monitor free chlorine in drinking water, rinse water, cooling water or other fresh water samples from 0.05-20 ppm chlorine as the standard range or 0.01-5 ppm with the low range sensor. The CDA330 is compliant with EPA method 334.0 for measuring drinking water.

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.​



  • ​Panel Mounted System Plug and Play Design

  • Amperometric Design

  • Automatic Flow Control

  • LXT330 Controller​

  • Compliant with EPA Method 334.0


  • ​Complete system, easy installation, ready to use

  • No expensive reagents

  • Eliminates pressure regulators and rotameters

  • Dual measurements, single parameter or dual parameter displays, MODBUS RTU, spray cleaner (optional for fouling applications)​


Sensor Specifications


​Polarographic, Gold/Silver, PTFE membrane, Digital Communication

​Measurement Range

​Chlorine:       0.05 to 20 ppm (High Range)
                       0.01 to 5 ppm (Low Range)​
pH:                 0 to 14 pH


​32° to 122ºF (0° to 50°C)


​38 L/hr to 300 L/hr (10 gal/hr to 80 gal/hr)

​Wetted Materials

​PVC, PP, PVDF, PTFE, Glass, 316 SS

​Process Connections

​Input 1/4" barb fitting, Drain 3/4" barb fitting

​Response Time

​T90 in 2 minutes

​Electrolyte Life

​​Up to 12 months

Analyzer Specifications


Chlorine:             0.05 to 20 ppm (Standard Range)
                             0.01 to 5 ppm (Low Range)
pH:                       0 to 14 pH

​pH Compensation

Not needed, ClO2, is not pH dependent


2.75"W x 1.5"H (128 x 64 pixels)
LCD, Black on Grey background, Blue on white background with LED back-light


IP65, weatherproof, 1/2 DIN
5.7"L x 5.7"W x 3.5"D


(1) 4-20 mA for Chlorine Dioxide, set to Sensor Range
(1) 4-20 mA for pH (optional), set 0-14 pH

Alarm Relay Ratings

Three (3) SPDT, 1 form C, 250 VAC, 10 Amp

Input Power

Standard:      100-240 VAC, 50/60 Hz, 4W, protected with 250V, 1A, Slow Blow Fuse
Optional:        24 VDC (18-36 VDC @ 250 mW minimum)​


​HART Protocol
Spray Cleaning (100V or 240V)
High Flow CFD
NEMA 4X System enclosure with clear or opaque door


​​Photometric Tester Kit, Calibration/Validation
Testing Strips
Membrane Replacement Kit
Sensor Polish Kit



​​​File Size

Model CDA​330 Broc​hure​​