Online Dissolved Oxygen Meter – OxySense

Which is the best online DO meter?

The OxySense DO meter from Pi utilizes a luminescent optical core from In Situ who are based in Colorado in the United States. This sensor core is incorporated into a specialist sensor housing designed by Pi for wastewater, either submersion in aeration lanes and oxidation ditches or in a different sensor body for use with a sensor flow block. The sensor measures from 0 to 20ppm and is extremely accurate and reproducible with self-cleaning and self-verification built in.

The OxySense dissolved oxygen sensor is robust, accurate and reproducible and is as close as it is possible to get to “fit and forget” dissolved oxygen measurement.

To find out more about OxySense, get in touch with one of our technical experts today.

What is the OxySense Online Optical DO Analyzer?

The OxySense Online Optical Dissolved Oxygen Analyzer with self-cleaning and self-verification offers enhanced reliability and unrivalled low maintenance. Optical DO meters have largely replaced electrochemical DO sensors (Clark Cells) due to their better reliability and lower maintenance requirements.

The OxySense DO sensor is available with different controllers giving you the same great performance with different communication, display, and control options.

If you have any questions or would like to find out more about OxySense get in touch with one of our technical experts.


The OxySense is an extremely rugged sensor, which provides long life and reliability even in harsh environments such as aeration lanes. Additionally, our automatic cleaning not only ensures that the OxySense isn’t fouled but also performs a self-verification check every time is it used.

The OxySense self-cleans using a blast of pressurized air to dislodge fouling on the sensor surface. The air line is integrated into the body of the probe, so the OxySense remains smooth and low profile to reduce ragging.

Because the automatic cleaning is performed with air rather than water, during cleaning the sample water is excluded from the end cap of the sensor. This allows for a verification check, as air covers the lumiphore and the reading should be much higher than in water. If this is not the case, the analyzer will flag an error to notify the operator.

Simple controls on the Pi analyzer control how often, and for how long, the sensor is cleaned and this can be set by the operator based on the demands of their process. A ‘hold’ signal can also be used to prevent the higher reading from self-verification in air from affecting data logs or output.

We would typically expect a lumiphore to have a lifespan of about three years, but this does vary from process to process.

Changing the lumiphore is quick and easy; simply pull the old lumiphore off and push the new one on. No changes are required on the analyzer.

Yes, it can. This might be more convenient on your site, where pressurized water might be more readily available than pressurized air. Self-verification is not available when cleaning with water, however; if this is required, Pi can supply an AirFlush compressor unit specifically designed to supply pressurized air to OxySense probes.

The sensing element (lumiphore) is activated, or excited when illuminated with a blue light. When activated, the lumiphore then emits red light in an intensity that is inversely proportional to the amount of oxygen present in the water. There is also a time delay between the peak emission of blue light and peak response of fluoresced red light. The amount of delay is inversely proportional to the amount of oxygen present. This time delay can be expressed as a phase shift between the wave patterns of incident blue light and the fluoresced red light. This is in turn reported by the electronics into a ppm or mg/l reading of Dissolved Oxygen.


Focus On

Focus Ons are a series of short articles distributed by email providing technical information regarding instrumentation, process measurement in potable, waste, process and pool waters. If you would like to join the mailing list, please contact us.

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