In-line Dissolved Oxygen Sensor

Dissolved oxygen is the level of free, non-compound oxygen, which is present in water or another liquid. In industrial processes or pure water systems it is typically measured with an in-line dissolved oxygen sensor.

In-line dissolved oxygen sensors are analytical instruments designed for continuous DO monitoring and control with real-time results for a range of industrial processes. In-line DO sensors from METTLER TOLEDO are optimal for in-line DO monitoring and control in pharmaceutical production, brewing, chemical production and pure water monitoring.

Monitoring and managing oxygen levels are important in many industrial processes. In-line DO sensors help optimize product yield and quality, reduce costs and ensure product safety.

Dissolved oxygen analyzers work based on the technology of METTLER TOLEDO in-line DO sensor selected. METTLER TOLEDO offers two in-line DO sensor technologies: Amperometric and Optical.

Amperometric: These in-line dissolved oxygen sensors use a gas permeable membrane to separate the sample from the electrochemical cell inside. Oxygen diffuses through the membrane in direct proportion to the partial pressure of oxygen in the liquid outside the in-line DO sensor. A cathode and anode inside the probe are polarized with a voltage to enable the electrochemical reaction of oxygen. Oxygen is reduced at the cathode while the anode is oxidized, producing a small current in direct proportion to the amount of oxygen in the sample. In addition, the dissolved oxygen sensor uses the temperature value to convert the oxygen partial pressure signal to a dissolved oxygen concentration value by compensating for the changing solubility of oxygen with temperature.

Optical: These in-line dissolved oxygen probes use optical technology for measurement. They contain an oxygen-sensitive layer that can fluoresce. This layer absorbs light from a light emitting diode in the sensor, and the light is released as fluorescence. The fluorescence lifetime depends on the amount of oxygen present in the sample medium.

Each in-line DO sensor has a specific calibration process than can be followed on its transmitter, or with ISM sensors, away from the process. To ensure high measurement accuracy of the in-line DO sensor, calibration must be carried out after each exchange of a sensor's spare part(s). Dissolved oxygen sensor calibration can be performed as a 1-point or 2-point calibration. For the 1-point calibration the normal calibration medium is air, for a 2-point calibration additionally a gas with 0% oxygen has to be used, which normally is pure nitrogen. The DO sensors can be adjusted also with a process calibration following a process sample or gas.

METTLER TOLEDO produces a wide range of in-line DO sensors with ISM technology. These sensors offer a strong digital signal to prevent signal interference so you can place your dissolved oxygen analyzer wherever you need it. They offer predictive diagnostics so that you know when your in-line DO sensor needs replacement parts or calibrated. With Plug and Measure technology you can calibrate your in-line DO sensor away from the process for fast sensor swapping when sensor exchange is required.