Parameter / Chlorine Dioxide 


chlorine dioxide

Chlorine dioxide is an instable, non-storable, toxic gas with a characteristic scent. The molecule consists of one Chlorine atom and two Oxygen atoms – represented in the chemical formula ClO2. It is very reactive. To avoid the risk of spontaneous explosions of gaseous Chlorine dioxide or concentrated solutions, it is generally handled in dilution with low concentrations. Chlorine dioxide is soluble in water, but tends to evaporate quickly. Typically it is prepared on site, for example from hydrochloric acid and sodium chlorite. The procedure provides solutions with approx. 2 g/l ClO2 that can be safely handled and stored for several days.



The disinfection effect of Chlorine dioxide is due to the transfer of Oxygen instead of Chlorine, so that no chlorinated byproducts are formed. Chlorine dioxide is used as disinfectant against biofilm, bacteria, spores, and viruses. Today it is believed that the molecule´s unpaired electron is transferred to the DNA of the microorganism which cracks and causes cell necrosis. Chlorine dioxide has a long-term effect of several days. In contrast to Chlorine, the disinfection strength of Chlorine dioxide does not depend on pH, and neither does the measurement show a pH influence in the range of 6-9 pH.



Chlorine dioxide is used as a disinfectant in cooling towers and air washers, in cleaning processes for bottles, fruit and vegetables, and in bleaching processes for paper and textiles. It is one of the few disinfectants allowed for drinking water disinfection in Germany.


Dr. A. Kuntze measurement

diagram sensor

We measure Chlorine dioxide potentiostatically with measuring and counter electrodes of pure gold and a Ag/AgCl reference. The measurement shows good selectivity towards Chlorine dioxide.A precise potential is applied to the measuring electrode, leading to an accumulation of negative charges on the metal surface. Chlorine dioxide molecules that hit the surface take a defined portion of the charge with them. The controller measures the potential between measuring and reference electrode and readjusts the charge on the electrode surface. The current necessary to maintain a constant charge is a direct measure for the concentration of Chlorine dioxide.


You would like to monitor the Chlorine dioxide concentration in your process?

We recommend our Krypton K: a complete measuring system with all necessary components, including a sampling point!The measuring system Krypton K ClO2 by Dr. A. Kuntze satisfied the examiners at the IWW. We asked the experts of the Rheinisch-Westfälisches Institute for Water in Mülheim to evaluate our Chlorine dioxide measuring system – with very good results. In particular, the measuring system was found to measure the Chlorine dioxide concentrations at the official limit values for drinking water in Germany – min. 0.05mg/l and max. 0.2mg/l – with the required statistical reliability. Click here to get the examination report.

For a more individual set-up select an instrument – either K 100 ClO2 for panel installation or K 100 W ClO2 with wall-mounting housing -, our membrane-free sensor AuAu-600-OO-2-1-PG, a flow assembly GD 3VG with defined incident flow, a sensor cable 5 SCR-M12-AE-X, and – if desired – our patented sensor cleaning ASR (cable included). We will be delighted to help you! Give us a call: +49 (0) 2150-7066-0


measuring point- Krypton K
measuring point- individual


You would like to monitor the Chlorine dioxide concentration in ambient air?

We recommend our K 100 (W) Gas CLO2. You can connect one or two gas sensors type GE 715 CLO2. The diagram shows a typical measuring set-up to monitor the ambient air in storage rooms.

gas measuring point

For each sensor two limit values can be defined, which operate separate relays. The first is supposed to activate an acoustic signal: by overstepping the limit value the alarm is set off. Manual acknowledgement switches off the relay. The second is supposed to activate the sprinkling system. A dela ycan be adjusted so that the sprinkling system starts only if the limit value is exceeded for a certain time. This relay can be switched off by digital input: if you connect a door contact, the sprinkling system will be switched off as soon as the maintenance personnel opens the door.



Plug & Play...
Our measuring systems for disinfectants contain all neccessary components and are equipped with safety features that allow a smooth measurement.


You don´t need to discard your measurement water any more. Thanks to our pressure-resistant sensors and assemblies you can redirect the water into the piping.


Maintenance is greatly reduced by our automatic sensor cleaning ASR. ASR keeps the electrode surfaces clean simply and environmental-friendly by electrolysis of water. More Information about ASR