Dissolved Ozone Sensor | pureO3

Ozone is a strong oxidizing gas that is injected into water or electrolytically generated in water. Dissolved ozone reverts back to harmless oxygen very quickly, depending on the temperature and pH of the water, so it must be generated and measured very close to the process. Dissolved ozone can be measured using a METTLER TOLEDO dissolved ozone sensor.

A dissolved ozone sensor is an analytical sensor that offers continuous monitoring and measurement of dissolved ozone in a water system.

The dissolved ozone probe from METTLER TOLEDO, the pureO3, uses a gas-permeable membrane to separate the sample from the electrochemical cell inside. Ozone diffuses through the membrane in direct proportion to the partial pressure of ozone outside the dissolved ozone sensor. The cathode (electrode from which conventional current leaves a polarized electrical device) and anode (electrode from which conventional current flows into a polarized electrical device) inside the probe are polarized with a voltage to enable the electrochemical reaction of ozone. Ozone is reduced at the cathode while the anode is oxidized, producing a small current in direct proportion to the amount of ozone reacting. A guard ring is provided around the cathode to protect the measurement from external interference. In addition, the dissolved ozone sensor uses the temperature value to convert the ozone partial pressure signal to a dissolved ozone concentration value by compensating for the changing solubility of ozone with temperature.

Calibration of a dissolved ozone sensor calculates new calibration constants for the sensor (zero current and a slope). Therefore, a zero current calibration procedure and a slope process calibration procedure have to be performed on the dissolved ozone sensor. For most applications, ozone-free air or water is used and provides the most reliable standard for the zero current calibration.