Calibration and adjustment

Calibration and adjustment are two operations used to verify and adjust the measuring capability of weighing instruments.

Both aim to guarantee and improve the accuracy of the instruments, and the two terms are often confused, but they have substantial differences.

So, what are calibration and adjustment, and how do they differ?

▷ Calibration

Calibration is a periodic check performed on an instrument to identify any measurement errors compared to a predefined standard.

It is used to asses its metrological characteristics (linearity, repeatability, etc.) and is carried out at different stages in the instrument's life, for example:

• before commissioning;
• after a repair;
• at predetermined intervals depending on its intended use.

Calibration is performed by comparing the instrument with reference standards of higher accuracy and does not require any adjustment intervention. It is also necessary to certify the quality of production processes according to ISO 9001 standards.

▷ Adjustment

▷ The differences

▷ Calibration is a test performed on the instrument to verify its metrological characteristics and does not involve any direct action on the instrument itself.

▷ Adjustment serves to correct measurement errors and requires a specific technical intervention.

▷ Appropriate equipment and certified reference measurement standards are required for calibration, which is why it is performed in a laboratory (or directly in the field) by accredited or specialized bodies and results in the issuance of a calibration document (calibration certificate or calibration report).

▷ Adjustment, on the other hand, is performed by the user or routine maintenance personnel. 
Adjustment is carried out directly on the instrument and only requires having sample weights available.

▷ Calibration should be requested periodically at intervals that may vary depending on the type of instrument, its application, and the regulations and requirements of the relevant sectors.

▷ Unlike calibration, adjustment does not need to be performed periodically. Usually, it is only repeated if verification or calibration activities reveal anomalies or problems.