ORP Sensors & Transmitters

ORP Sensors & Transmitters

Oxidation-Reduction Potential (ORP) sensors measure the redox potential of a solution, providing a practical indication of oxidizing or reducing conditions. ORP measurement points consist of a noble-metal electrode (commonly platinum or gold), a stable reference system, and a transmitter that delivers trending and integration into control systems.

ORP is especially valuable when the overall oxidative “strength” of the medium matters more than a single chemical species. It provides trend information for disinfection capability, supports control of aeration and biological redox zones, and helps manage detoxification reactions where the process objective is to drive the system to a consistent redox endpoint rather than maintain a specific ppm value of a reagent.

Electrode selection is application-dependent. Gold electrodes are commonly associated with oxidation processes such as cyanide oxidation and ozone measurement, while platinum electrodes are used in reducing processes such as chromate reduction or in applications tied to chlorine dosing control concepts. Selection of diaphragm and reference design is equally important for stability in challenging media, and measurement systems are available for standard, hygienic, and hazardous-area requirements.

Applications include drinking water and swimming pool disinfection monitoring, wastewater treatment aeration control and redox zone management, and industrial processes such as electroplating bath detoxification and flue gas scrubbing where oxidation/reduction chemistry is central. ORP trending is frequently used to verify chemical feed performance and to detect process drift before quality limits are exceeded.

Reliable ORP measurement depends on controlling fouling and maintaining a healthy reference junction. Installation design (flow, immersion depth, and avoidance of stagnant pockets), periodic cleaning, and verification against known redox standards are common practices. ORP is often interpreted alongside pH and other context parameters to improve diagnostic clarity and control robustness.

George E. Booth Co., an exclusive authorized representative of sales and service for Endress+Hauser.