Online Chlorine Dioxide in Water Controller – DioSense

How is chlorine dioxide in water measured online? Online, continuous Chlorine Dioxide Analyzers and Controllers make up the DioSense range, which utilizes the best and most recent chlorine dioxide sensors available worldwide.

The DioSense chlorine dioxide sensors are membraned electrochemical sensors that don’t respond to chlorine, use no reagents, are incredibly stable and have less maintenance and reduced maintenance costs.

ClO2 is often used in challenging environments where sample preparation is key to making the sensors work reliably and for a long time between maintenance. Pi specializes in sample preparation.

The DioSense Residual Chlorine Dioxide Analyzer is used in numerous applications, wherever the residual ClO2 is controlled to ensure effective disinfection.

Pi’s chlorine dioxide analyzers are designed to have reduced maintenance, reduced calibration and reduced spares requirements. Often used to control both chlorine dioxide generators and also the levels of residual chlorine dioxide in water, DioSense is suitable for all applications in all industries.

Chlorine dioxide monitors are often used to monitor the residual ClO2 in difficult ‘dirty’ applications such as in hospitals or the food industry. In these cases, in order to maintain an appropriate chlorine dioxide residual it is necessary to automatically clean the sensor using the AutoFlush.

If you think your application could need the AutoFlush, please contact us and discuss it with our experienced technical sales people.

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Although it contains the word ‘chlorine’, there are distinct chemical differences between chlorine dioxide and what is normally referred to as chlorine disinfectant (hypochlorite).

We have many years of experience with chlorine dioxide applications at Process Instruments. If you are in any doubt, please do not hesitate to contact us via phone or email; details can be found on the ‘Contact Us’ page.

While chlorine disinfectant is used the world over and is effective at maintaining drinking water safety, chorine dioxide does have a number of advantages:

  • It is possible to generate chlorine dioxide on site, making transport and storage unnecessary.
  • Because chlorine dioxide disinfects via an oxidative reaction rather than a chlorinating one, disinfection by-products are not produced. This avoids the presence of compounds such as trihalomethanes (THMs) which have been linked to an increase risk of cancer.

When surface waters have taste and odor problems, chlorine dioxide can be an ideal primary disinfectant. Effective at concentrations as low as 0.1ppm and across a wide pH range, chlorine dioxide effectively penetrates bacterial cell walls to rapidly cause cell death. Industrial water applications (e.g. hot water loops, food washing) often use chlorine dioxide because of this.

Chlorine dioxide, when stored and handled properly, is perfectly safe to use. Like many disinfectant chemicals, chlorine dioxide has the potential to be harmful; this is what makes them effective at their intended purpose, and so prolonged exposure, contact or consumption is to be avoided. 


It is appropriate to consider chlorine dioxide as environmentally friendly, as it effectively eliminates bacteria and doesn’t produce some of the harmful by-products associated with chlorine disinfection.

Chlorine dioxide solutions should be stored in the absence of light, in an airtight container and at low temperatures (around 5°C). Under these conditions, solutions around 1% (10g/l) can be stored safely for several months with only a small change in concentration.

Chlorine dioxide can be generated electrochemically, or chemically with either sodium chlorite or sodium chlorate.

The cost of chlorine dioxide will depend upon the method used to generate it and the price of the chemicals used (sodium chlorite or sodium chlorate). While the equipment used for chlorine dioxide generation is less expensive compared to that for other options, chlorine dioxide has a greater cost than chlorine. However, for some applications chlorine dioxide is more appropriate, and so end users choose ClO2 for its different properties.

The terms ‘monitor’ and ‘analyzer’ are basically interchangeable and refer to an instrument that can measure/display certain parameters. A ‘controller’, as the name suggests, refers to an instrument that also has onboard control functionality. All Pi systems can have this functionality, and so a DioSense can be considered a monitor/analyzer and also a controller.