Glossary · Sensors and measurement
Conductivity sensor
Also known as: Conductivity cell, Conductivity probe
German: Leitfähigkeitssensor
In process instrumentation, a conductivity sensor is a sensor that measures the electrical conductivity of a liquid, either with electrodes in contact with the medium or inductively with toroidal coils. Most conductivity sensors include a temperature sensor for compensation.
- Sensors
- Process industry
In one sentence
A conductivity sensor measures the electrical conductivity of a liquid with electrodes or toroidal coils, usually with built-in temperature compensation.
Example
An inductive conductivity sensor in the return line of a dairy cleaning system detects the transition between product, water and cleaning agent.
How it applies
- Engineering: Select the sensor type by conductivity range, medium, temperature and hygiene requirements. Electrode sensors are specified by their cell constant; inductive sensors need enough free space around the toroid because nearby pipe walls influence the reading.
- Installation: Air bubbles and deposits distort the reading. Mount the sensor so that it is always fully immersed and flow passes the measuring zone.
- Maintenance: Electrode sensors can polarize or foul. Clean them and verify them with a reference solution at the documented interval.
- Documentation: Record the cell constant, installation factor and temperature compensation for each sensor. Replacement instructions should say which of these must be re-entered in the Transmitter.
Conductivity sensor vs. conductivity measurement
The sensor is the device in the process. Conductivity measurement is the method around it, including temperature compensation and evaluation.