Gauging, calibration, adjusting – what exactly?

It is easy to get lost in the jungle of terms used in measurement technology. Calibration, gauging, adjustment – to the layman, those terms sound similar at first. Far from it! Because the activities are clearly different from each other. It is time for a definition suitable for everyday use:

Gauging
Gauging may only be performed by state authorities, the verification offices. Gauging is a test prescribed by law, during which the test equipment is examined for compliance with the prescribed measured values in accordance with the Measurement and Calibration Act. Furthermore, only measuring instruments whose design has been certified as verifiable in an approval procedure may be gauged.

What is the purpose of gauging? Consumer protection: All measuring instruments whose measurement accuracy is in the public interest (for example, because the results are used to set prices) are subject to legal verification. These include, for example, fuel dispensers at gas stations, water meters and scales in retail outlets.

Calibration
Calibrations are performed by calibration laboratories (e.g., CAT Group). You can compare the display of a measuring device with a reference device or a standard. This is a target/actual comparison that quantifies the deviation of a measured value from the standard. Calibrations are carried out under precisely defined reference conditions; technical interventions on the measuring instrument devices (?) are not part of the process.

Calibration includes documenting the measurement deviation (measurement accuracy of the test specimen), calculating the measurement uncertainty, and issuing a calibration certificate or certificate.

What is the purpose of calibration? First, it ensures that legal regulations and standards such as DIN EN ISO 9001, GMP or FDA are met. This is because every measuring device is subject to changes due to wear or contamination – calibration thus serves quality assurance. Calibration documentation is also used for international comparability of measurement results.

Adjustment
In contrast to calibration, adjustment involves intervention in the measuring system. If, for example, the measurement deviation between the display value of the measuring device and that of the reference device is impermissibly high, the measuring device must be adjusted so that it provides accurate data again. The adjustment is done partly via potentiometer, but also via device menu or PC software.

What is the purpose of adjustment? If deviations that are unacceptable are detected during calibration, the adjustment – i.e., the correction of the measurement deviation on the device – is carried out.

Published: July 2023