The Walchem WDS Series sensors’ differential measurement technique uses two electrodes, one for the process measurement and the other for the reference measurement. Each electrode is measured differentially with respect to a third metal electrode. The reference electrode is constructed from pH glass and is embedded in pH 7 buffer within the sensor behind a porous, replaceable salt bridge. If the reference solution becomes contaminated, or the salt bridge becomes clogged, it can be easily replaced. The glass electrode is not prone to chemical attack like a silver/silver chloride reference can be, adding to the reliability of the sensor.
