Dissolved Oxygen Sensors

Dissolved oxygen (DO) sensors perform liquid process measurement for determining the amount of oxygen dissolved or carried in the process liquid. There are three common technologies for dissolved oxygen measurements: polarographic, galvanic and optical. The standard units of measure are milligrams per liter (mg/l), parts per million (ppm), parts per billion (ppb), or % saturation. Various installation options including floating ball, retractable, flow thru, immersion, and direct insertion. 

  • Measuring Sensor DO30G

    The DO30G sensor for dissolved oxygen is designed for use in water treatment plants such as sewage treatment works, effluent activated sludge process, and potable water treatment. It is also effective in river monitoring, intake protection, fish farming, and other fields where water quality is important.

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  • Sensors for ppb Applications

    Dissolved oxygen measurements in the parts per billion range are critical in, but not limited to power generating plants. Maintaining a low level of dissolved oxygen in boiler feedwater assures that corrosion of certain components is minimized. A reliable measurement of ppb dissolved oxygen helps to reduce downtime and improve efficiency.

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  • Optical Dissolved Oxygen Sensor, Hamilton VisiFerm

    Hamilton's VisiFerm is the first optical sensor ever for the measurement of dissolved oxygen that has significant advantages compared to classical Clark cells because there's no electrolyte needed and the luminophore is embedded in a robust sensor cap. Typical applications are biotechnology, water treatment and monitoring as well as in breweries, wineries and soft drink processing.

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Dissolved Oxygen Sensor Applications

Water treatment dissolved oxygen monitoring equipment like the DO30G:

  • Sewage treatment
  • Effluent activated sludge process
  • Potable water
  • River monitoring 
  • Intake protection
  • Fish farming


  • Pharmaceutical applications
  • Chemical plants

Parts per billion dissolved oxygen measuring instruments like OXYGOLD G/B:

  • Brewing
  • Electrolysis plants
  • More

Optical DO Sensors like VisiFerm:

  • Biotech
  • Chemical industry
  • Air surveillance
  • Fish farming
  • Water management
  • Gas and liquid phase sewage water

Low PPB Optical DO Sensors like VisiTrace:

  • Power plant
  • Food/beverage
  • Low-downtime product quality maintenance

Dissolved Oxygen Sensor Working Principle

Membrane electrode dissolved oxygen measurement (galvanic cell, polarographic):

Without interference from the pH, oxidation, reduction substances, or turbidity of the water, this method measures a reduction or diffusion current created by dissolved oxygen concentration or oxygen partial pressure. An air layer forms on the membrane of the sensor in the water, and the oxygen concentration of that layer is in equilibrium with the water's dissolved oxygen concentration.

Optical measurement of dissolved oxygen process:

The optical oxygen sensor probes a cell culture container and uses fluorescent dye and a fiber optic reader to display a liquid's luminescence in the presence of oxygen. Higher oxygen levels yield lower emission intensities, so the DO can be measured via the luminescence peak, decay rate, or the signal phase difference.



When used to measure the dissolved oxygen in an aeration tank, sensors tend to quickly become contaminated and need frequent cleaning.


Removal of free oil and grease from a wastewater stream reduces the potential for equipment problems downstream. Three forms of oil are encountered in wastewater treatment at a refinery: Free Oil, Emulsified Oil, Dissolved Oil.


Having too much oxygen in the process is not a problem for the biological system; however the cost for generating the oxygen is one of the largest expenses. By obtaining a good representative average of the dissolved oxygen present in the basin could save the plant large amounts of money. For this reason multiple measurements points are sometimes put into place.


The detectors used to perform dissolved oxygen (DO) measurement in oxidation ditch type sewage treatment plants tend to become dirty quickly and require frequent cleaning.

We recommend returning your ZR402G to the factory for display replacement. There are several reasons: There are 2 generations of displays for the ZR402G: the Green display and the White display. The green displays were used on the early mode...
How to startup a new sensor, or how to replace the Membrane Cap and Electrolyte.   Startup of a new Oxygold G sensor: The Oxygold G sensor is shipped dry with a protective cap over the end of the Membrane Cartridge. CAUTION: The electrolyte ...



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