Dissolved Oxygen

Dissolved Oxygen Measurement

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WTW Dissolved Oxygen Measurement

The measurement of dissolved oxygen has it biggest importance in environmental analysis, but also in some industrial applications.

In its simplest form a dissolved oxygen sensor contains a working electrode and a counter-electrode. Both electrodes are located in an electrolyte system which is separated from the sample by a gas-permeable membrane. The working electrode reduces the oxygen molecules to hydroxide ions. In this electrochemical reaction a current flows from the counter-electrode to the working electrode. The more oxygen is present in the sample, the larger the current signal. From this signal the D.O. meter calculates the concentration of dissolved oxygen in the sample.

The optical method uses the so-called fluorescence quenching. The membrane contains a special dye which is excited by light. The fluorescing light will be changed in its intensity and phase by oxygen. This signal change can be detected and evaluated. It is the principle of modern optical D.O. sensors which also digitally process the signal and send it to the meter.


• inoLab® Laboratory Dissolved Oxygen Meters

• Portable Dissolved Oxygen Meters

• Galvanic Dissolved Oxygen Sensors

• Digital IDS Dissolved Oxygen Sensors

• Accessories


inoLab® Laboratory Dissolved Oxygen Meters


Sets for benchtop meters

All benchtop meters are available in application oriented sets including sensors and accessories.

Determining dissolved oxygen …

… with the innovative inoLab® Multi 9310 IDS


inoLab? Multi 9310P IDS

  • Optimum measuring quality
  • Digital sensor recognition
  • Intelligent sensor rating

IDS Sauerstoff-Elektroden

The new inoLab® Multi 9310 IDS is ideal for digital, optical DO measurements in the laboratory. The IDS technology perfectly supports measuring in the easiest way along with efficient documentation. Without self consumption and resistant against air bubbles, carbon dioxide and ethanol the optical DO sensor FDO® 925 is not only recommended forBOD measuring, but also for further applications throughout the laboratory.

Measuring safety

  • Through digital transmission of signals the sensor data is easily provided.
  • Display of service information for supporting the ideal function.
  • Maintenance free measuring system without use of chemicals through factory calibrated sensor cap
  • Automatic air pressure compensation for precise measuring results

Measuring channel 1 (universal)
Display LCD graphic, backlit
Data storage Manual: 500 data sets/Automatic: 5000 data sets
Logger Manual/time-controlled
Interface Mini USB
Printer (optional) Thermo printer, width 58 mm
Power supply Universal power supply 100 to 240 V, 50/60 Hz, 4 x 1,5 V AA or 4 x 1.2 V NiMH rechargeable battery

Reliable DO documentation…

… with the inoLab® Oxi 7310


inoLab Oxi 7310

The new inoLab® Oxi 7310 is the perfect laboratory meter for measuring DO with the proven galvanic DO sensors. With automatic GLP/AQA documentation it supports traceability not only in the environmental laboratory. On demand also available with built-in printer.

Measuring safety

  • Repeatable measuring results provided by the active, automatic AutoRead function with recognition of stable end values
  • Automatic air-pressure compensation
  • Graphic display with plain text menu for convenient and secure operation

Flexible and powerful:

  • Measures partial pressure, concentration and saturation
  • Salinity corrections
  • Storage for large measuring batches

  All values ±1 digit
Concentration 0.00 … 20.00 mg/l ±0.5 % Mw.
0 … 90 mg/L ±0,5 %
Saturation 0.0 … 200.0 % ±0.5 % v. Mw.
0 … 600 % ±0.5 % v Mw.
Partial pressure 0 … 200.0 hPa, 0 to 1250 hPa
Temperature -5.0 … 105.0 °C ±0.1 °C