pH – ORP Sensors

pH is the most frequently measured analytical parameter in process industries, and ORP (oxidation-reduction potential) is its companion for disinfection, chrome reduction, cyanide destruction and other redox reactions. Both are measured with a glass or metal electrode against a reference electrode, and the quality of the measurement depends almost entirely on how well the reference junction survives the process. Industrial sensors use double-junction or solid references, replaceable salt bridges and rugged bodies to give months of service where a laboratory electrode would last days.

Sensors cover pH 0 to 14 and ORP −1,500 to +1,500 mV, with an integrated temperature element for compensation, at process conditions to 25 bar and 155 °C. Process connections are ¾" and 1" for direct insertion in tees and vessels, or retractable assemblies that let the sensor be withdrawn for cleaning and calibration without depressurising the line. Variants are available for high-temperature and high-pressure processes and for corrosive media, with flat-glass, hydrofluoric-acid-resistant and low-conductivity options according to the application.

The sensors connect to single- or dual-channel transmitters delivering 4–20 mA, HART or FOUNDATION Fieldbus, and are supported by mounting adapters, flow cells, calibration solutions and cables from the accessories range.

Applications are general process pH and ORP measurement, scrubbers, neutralisation, boiler and cooling water, effluent and disinfection in chemical, petrochemical, refining, power, water and wastewater, food and beverage and pulp and paper.