Dissolved Oxygen Measurement: Polarographic vs. Optical DO Sensors

This video discusses the impact of unplanned power plant shutdowns that result from water cycle chemistry issues. Cycle chemistry that is monitored ineffectively can lead to corrosion and other damage to critical power plant equipment that requires costly repairs and results in lost revenue that can never be recovered. Measuring dissolved oxygen can improve water system efficiency and help to avoid unplanned shutdowns.
Polarographic sensors are often used to monitor dissolved oxygen in the power plant water cycle. However, these sensors require frequent maintenance for electrolyte and membrane replacement, and then measurement is delayed after service due to necessary polarization. Polarographic sensors are also susceptible to interference from dissolved hydrogen. In this video, you will learn how Optical Dissolved Oxygen sensors eliminate the limitations of traditional polarographic sensors, and provide faster measurement for more efficient cycle chemistry monitoring. This allows power plants to operate with lower costs, reduced downtime, and helps to control corrosion.
To learn more about the Pure Water Optical DO Sensor, download the white paper, "Minimize Power Plant Corrosion with Improved Optical DO Technology"
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To request more information or pricing on a Pure Water Optical DO Sensor, visit:
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The METTLER TOLEDO Pure Water Optical DO Sensor incorporates the latest technology to combat previous limitations of optical sensors, such as the lifetime of the chromophore used to provide accurate and reliable oxygen detection. In this sensor, the chromophore is housed in an easily replaceable unit, the OptoCap, which allows simple and infrequent maintenance. In fact, the only maintenance required for the Pure Water Optical DO Sensor is an annual replacement of the OptoCap.
In addition to improvements to optical dissolved oxygen technology, instrumentation advancements also provide efficiency and reliability in power plant water cycle chemistry monitoring. A multi-parameter, multi-channel transmitter can accommodate a dissolved oxygen measurement in combination with other critical cycle chemistry measurements, such as conductivity, pH and ORP. This provides convenience when multiple measurements are required to maintain a water treatment scheme.
METTLER TOLEDO produces a full range of solutions for monitoring and managing power plant water cycle chemistry. To learn more about our solutions for power plant water and steam monitoring, download the guide on optimizing your power plant chemistry:
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[@mandapallisivakumar197]

How to calculate Dissolved oxygen in mg/L using Galvanic DO probe sensor (mV output)?

[@METTLERTOLEDOProcessAnalytics]

Hi Mandapalli, Our analog amperometric sensors (also called polarographic; clark cell) output signal is a nano ampere signal (electron flow). The signal is resulting from a electrochemical reaction of the measurement cell and triggered by the polarization voltage.
The signal is linearly dependent on the amount of oxygen diffused eg. reduction at the cathode of the cell.
Other factors like temperature, diffusion coefficient,; see below are also influencing the calculation.
The calculation you're looking for would be based on Frick's Law, which is detailed further on pages 24-25 of our Oxygen Theory guide. You can download that for free here:
www.mt.com/global/en/home/library/guides/process-analytics/oxygen-theory-guide.html

[@rushiGentleMen]

Can this be used in aqua farms?

[@METTLERTOLEDOProcessAnalytics]

Dear Rushi Bhargav, thank you for reaching out 🙂
Optical DO sensors suitable for an aqua farm would be the InPro 6970i (measures down to 2 ppb) - www.mt.com/global/en/home/products/Process-Analytics/DO-CO2-ozone-sensor/dissolved-oxygen-meter/optical-dissolved-oxygen-sensor/inpro6970i-12-120.html
and the InPro 6860i (measures from 8 ppb to saturation) - www.mt.com/global/en/home/products/Process-Analytics/DO-CO2-ozone-sensor/dissolved-oxygen-meter/optical-dissolved-oxygen-sensor/inpro6860i-hd-120-ma.html.
Hope that helps🙂