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 waste water, 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.
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.
The OxySense from Pi comes with a number of benefits, the most exciting of which is the auto-verification that happens every time the sensor is cleaned with air. This is made possible by the design of the sensor which means that the water is excluded from the front of the sensor during the cleaning operation which allows the sensor to respond to the oxygen in the compressed air that is cleaning it. The controller monitors the response of the sensor and ensures that it responds appropriately to the oxygen in the cleaning air thereby verifying that the sensor is responding to dissolved oxygen as it should.
By far the largest application for ppm dissolved oxygen monitoring is in aeration lanes in activated sludge wastewater treatment plants. The monitoring of DO is essential to control the blowers that pump air into the sludge in the aeration lanes to keep the bacteria that digest the sludge alive. The cost of the electricity to run the blowers can often be up to 50% of the cost of running the plant and therefore keeping just enough oxygen in the water is crucial to making the plant efficient. In order to do this, great reliance is placed upon the online monitoring of dissolved oxygen. This monitoring must be reliable and reproducible. The OxySense from Pi utilizing the In Situ RDO sensor gives the reliability, accuracy and reproducibility that operators need in order to maintain the perfect dissolved oxygen level in the activated sludge and therefore keep the plant as efficient as it is possible for it to be.
The most difficult part of continuously monitoring dissolved oxygen in activated sludge is keeping the sensors clean. A fouled sensor will measure lower dissolved oxygen than is actually present in the aeration lane and will drive the blowers up to put more and more oxygen into the sludge at increased electrical cost. Keeping the sensors clean manually can be a full-time job for an operator. The OxySense from Pi has an inbuilt auto-cleaning capability thereby keeping the sensor clean all of the time.
If you would like to run a trial in your plant or would like to learn more about the OxySense from Pi then why not contact us?
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.
A multi-parameter analyzer from Pi attracted many customers to Beijing Anyuan’s exhibition space at the China Water Supply Conference 2021 and Pi’s representative based in
A new Dissolved Oxygen (DO) monitor and ORP monitor with automatic sensor cleaning from Process Instruments, via its North American municipal water and waste water
Dissolved Oxygen sensors almost always require self-cleaning to ensure accurate readings in difficult applications like aeration lanes on waste water treatment works. Pi releases two
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