ABSTRACT
The measurement and control of oxidation-reduction potential (ORP) is applied in an increasing number of applications in both processing and wastewater treatment. Oxidation-reduction reactions are reactions in which the substances involved gain or lose electrons and show different electron configurations before and after the reaction. The basic instrumentation for ORP measurement closely parallels that for pH measurement. In fact, many instrument suppliers use slightly modified pH analyzers, the main modification being a changed sensitivity and an mV scale in place of a pH scale. There are two major differences between an ORP system and a pH system. ORP and pH electrodes can often be mounted in the same tees or flow-through chambers and can have practically identical appearances. Maintenance of an ORP measuring and control system is generally comparable to that of a similar pH system. Most applications of process ORP instruments involve control.
