Glossary · Sensors and measurement
Conductivity measurement
Also known as: Electrical conductivity measurement
German: Leitfähigkeitsmessung
In process instrumentation, conductivity measurement determines the electrical conductivity of a liquid, usually in microsiemens or millisiemens per centimeter. Because conductivity depends on dissolved ions and temperature, results are normally referenced to 25 °C.
- Sensors
- Process industry
In one sentence
Conductivity measurement determines how well a liquid conducts electricity, a quick indicator of dissolved ions, concentration and purity.
Example
In a clean-in-place system, conductivity measurement tells the controller when the rinse water has displaced the caustic cleaning solution.
How it applies
- Engineering: Two-electrode (conductive) cells suit low conductivities such as pure water; inductive (toroidal) sensors suit high conductivities and dirty or aggressive media because they have no electrodes in contact with the liquid.
- Operation: Conductivity is used for phase separation, concentration monitoring of acids and caustics, water quality and leak detection. The controller usually works with temperature-compensated values.
- Maintenance: Check the cell constant with a reference solution and keep the compensation settings documented.
- Documentation: Always state whether a value is compensated and to which reference temperature. A number without this is ambiguous in operating instructions and reports.
Conductivity measurement vs. conductivity sensor
Conductivity measurement is the method, including temperature compensation and evaluation. The Conductivity sensor is the device in the process that delivers the raw signal.