Global Water's EZ100 ORP Meter Display adds visual monitoring capabilities to the ORP sensor.  The EZ100 ORP Meter Display connects to the ORP sensor's 4-20mA output to a LCD screen for viewing data.  In addition, Global Water offers the PC300 ORP Controller to use the ORP sensor's output to control pumps or alarms.

Measuring ORP
ORP stands for oxidation-reduction potential, which is the measurement (in millivolts, or mV) of the oxidizing or reducing tendency of a solution.  Oxidation is the loss of electrons from an atom, molecule, or ion, which may or may not be accompanied by the addition of oxygen.  When a substance is oxidized, its oxidation state increases.  Reduction is the net gain of electrons.  When a substance is reduced, its oxidation state is lowered.  Oxidation and reduction reactions always accompany each other.  Every oxidation and reduction reaction can be characterized by a halfreaction, which provides all of the chemical substances participating in the reaction (many half-reactions are identified in standard chemistry handbooks or other reference materials).  The ORP of the solution depends on the concentrations of the substances participating in the half-reaction.  In order to calculate ORP when concentrations vary, you must use the Nernst equation.  Due to its logarithmic dependence on concentration and its dependence on multiple solution components, ORP is typically not a good method for measuring concentration.  The best use of an ORP is in monitoring and controlling oxidation-reduction reactions.  When an oxidation-reduction reaction occurs, there is usually a large change in the ORP, which overwhelms the factors that make concentration measurements an issue.  This allows you to ensure that an ORP reaction has gone into completion, and thereby control your application appropriately.

ORP Sensors Specifications