Redox Electrode
A Redox electrode develops a potential in response to the redox potential of the solution in which it is immersed. A Redox or ORP measuring electrode is identical to a pH measuring electrode except a metal electrode is used instead of the pH glass as the measuring element.

Most Redox electrodes used in industrial applications use an inert metal electrode of Platinum or Gold. Combination Redox electrodes may either have a glass bulb with a Platinum band or a Platinum tip. Gold Redox electrodes can offer a performance advantage over Platinum Redox electrodes when used in strong oxidising solutions.

The reference electrode is identical to the one used in a pH electrode. It has a Silver/Silver Chloride wire in 3.5M KCl saturated with AgCl (Silver Chloride). A combination Redox electrode works in a similar way to a combination pH electrode.

The measuring electrode generates a millivolt output based on the oxidizing or reducing reactions taking place while the reference electrode generates a constant millivolt output. The working range of an ORP electrode is +/- 2000mV. A Redox meter with a millivolt scale or ORP transmitter or controller is used to display readings.

Unlike pH electrodes, Redox electrodes undergo no changes of zero point or slope but incorrect measurements can occur when there is a contaminated metal electrode. As Redox electrodes age the speed of response slows. If the Platinum band or metal electrode of a Redox electrode becomes scratched or coated this will also result in slower response. Platinum bands or metal electrodes can be cleaned.

Operation of Redox electrodes can be checked using standard Redox calibration solutions which LTH Electronics can supply; a single point calibration is all that is required.

LTH Electronics offer a range of Redox electrodes to suit most process applications in many different configurations for tank or pipe mounting applications. Self-cleaning and spray wash adapters can be fitted to the Redox electrodes to reduce maintenance in waste streams that normally coat the electrode.

Call us on +44 (0)1582 593693 or email sales@lth.co.uk to find out how we can help you.