How to choose ORP sensors and how to maintain ORP electrodes?

ORP is the oxidation-reduction potential, which is used to reflect the macroscopic oxidation-reduction properties of all substances in aqueous solution. The higher the redox potential, the stronger the oxidation, and the lower the redox potential, the stronger the reduction. A positive ORP value indicates that the solution exhibits certain oxidizing properties, and a negative ORP value indicates that the solution exhibits certain reducing properties. ORP sensors are used to measure the ability of a solution to oxidize or reduce. ORP electrodes are widely used in various water quality treatment occasions, such as testing the purity of drinking water, monitoring the anaerobic activity of wastewater, and some processes in sewage treatment.

The ORP electrode is an electrode that can absorb or release electrons on the surface of its sensitive layer. The sensitive layer t is an inert metal, usually made of platinum or gold. The ORP electrode developed and produced by Daruifuno is a composite electrode, and we use platinum metal. Electrodes are available in two sizes: flat platinum and circular platinum.

Flat platinum is easy to clean and polish, and is suitable for clean water environments. Ring platinum has a wider measurement range and is suitable for sewage environments.
If your water quality is normal temperature, choose ASR300 series, ABS shell; if the water temperature is high and the water quality is complicated, you can choose ASR400 series, PPS shell, which is more resistant to high temperature and corrosion. In addition, we also have ORP electrodes with glass housings, which can be used with Flow cells, etc. If you want a more advanced ORP electrode, we also have a digital version with built-in RS485, which can realize data output and facilitate networking.

How to maintain ORP electrodes?
The platinum metal surface of the ORP electrode should be bright, and the response of the rough surface to the redox potential is much slower than that of the bright surface electrode. And after long-term use, the surface contamination of platinum will also lead to inaccurate measurement and slow response, so the electrode must be cleaned and activated:
1) For inorganic pollution, the electrode can be immersed in 0.1mol/L dilute hydrochloric acid for 30 minutes, washed with pure water, and then immersed in the electrode soaking solution for 6 hours before use.
(2) For organic oil and oil film pollution, the surface of platinum or gold can be cleaned with detergent and then cleaned with pure water, and then immersed in the electrode soaking solution for 6 hours before use.
(3) Platinum surface is seriously polluted and an oxide film is formed on the surface. You can use toothpaste to polish the platinum or gold surface, then wash it with pure water, and then immerse it in the electrode soaking solution for 6 hours before using it.

The ORP meter does not need to be calibrated when it is used, it can be used directly. Only when there is doubt about the quality or test results of the ORP electrode, the ORP standard solution can be prepared to test its mV value to determine the good ring of the ORP electrode or instrument.

The above is the introduction about the ORP electrode. Delfino focuses on the R&D, production and sales of water quality analysis instruments. Its main products include online pH ORP analyzer, conductivity analyzer, turbidity analyzer, dissolved oxygen analyzer, COD analyzer, ammonia analyzer, suspend solid sensor, chlorine analyzer, etc. If you need water treatment related products, please contact us.