High Range Online Chlorine Dioxide (0-0.35%) – DioSense HR

How do you continuously measure high concentrations of Chlorine Dioxide solution online? Measuring a high level of ClO2 in solution is extremely difficult and has been traditionally done with expensive at-line optical instruments. The DioSense HR (0-3500 ppm) is an optical sensor measuring the absorbance of light at a particular frequency which is proportional to the amount of chlorine dioxide in the solution.

Why is it necessary to measure the chlorine dioxide content of water online and continuously? Chlorine dioxide generators often make chlorine dioxide solutions in several stages, starting with a high concentration and diluting to a lower concentration. Knowing the concentration of the higher concentration solution greatly improves the dilution process giving a much better controlled final ClO2 solution concentration.

The DioSense HR has been designed to three criteria:

  • The Best Sensor Available – the DioSense HR is an optical measurement where the amount that a certain wavelength is absorbed is directly proportional to the amount of chlorine dioxide in a sample.
  • The Best Control Possible – for chlorine dioxide generators that use multiple stage dilution Process Instruments has a sensor to measure the ClO2 at each stage thereby allowing the next stage dilution to be more precise, accurate and reproducible.
  • Reduced Costs – knowing how much chlorine dioxide is in your solution means that over generating is a thing of the past. If you are a manufacturer of chlorine dioxide generators then you can manufacture to the right concentration and not overshoot. All of these benefits will save you money in your process.
DioSense HRBrochure650kB


Chlorine dioxide is a gas, commonly used as a disinfectant when dissolved in water

There are a couple of ways to make a chlorine dioxide solution. It is usually made by mixing sodium chlorite with another chemical such as hydrochloric acid. Other methods include the electrolysis of sodium chlorite or starting the chemical reaction with sodium chlorate instead of sodium chlorite.

Chlorine dioxide manufacturing can be expensive and time consuming. The ClO2 levels need to be consistently monitored to ensure that the concentration produced is safe and is produced at the minimum cost.

Nothing. Sensors are often affected by temperature, but the HypoSense has a built-in internal thermistor that allows for automatic temperature compensation meaning that you don’t have to worry about variations in temperature.

All of Pi’s chlorine dioxide sensors have very low drift rates so how often you calibrate your sensor, depends on the application. Our customers range from people who calibrate once a week to once a month, even to once every six months.

Usually the DioSense HR is maintenance free as chlorine dioxide should keep the sensor clean. If the application is in dirty water, the sensor may require additional cleaning.

Yes. The DioSense HR uses light absorption to make a measurement, so bubbles blocking the flow of light will cause an erroneous reading. One way to solve this problem is to ensure the ClO2 flow path is vertical rather than horizontal. This can be done when mounting the sensor. A vertical flow path will help to force the bubbles away.