Calibration of temperature instruments can be done in liquid, air or in a block calibrator. What determines which medium to use is the type of temperature sensor and the temperatures in question.

The sensor from the temperature instrument is mounted close to a reference sensor with known correction. They are heated or cooled to the wanted temperature levels and the temperature has stabilized.

The difference between the reference sensor and the calibrated sensor will generate a correction term, which will be added/withdrawn from the showed temperature on the calibrated temperature instrument.

Consideration must be made to the uncertainty components such as ambient temperature, resolution, stability, operation etc. This will generate a measurement uncertainty on the result (e.g. ±0,2 °C), which must be considered when using the temperature instrument.

Ann-Christin Johansson