What does calibration mean?


Calibration means determining and documenting the deviation of the display of a measuring device from the reference value. According to the 2012 German edition of the ‘International Vocabulary of Metrology’, calibration is defined as “… Activity which, under specified conditions […] establishes a relationship between the quantity values ​​provided by standards with their measurement uncertainties and the corresponding displays with their associated measurement uncertainties.

Calibration should not be confused with adjustment of a measurement system, which is often called ‘self-calibration’, nor with calibration verification. …”

What is calibration?

Calibration means that measurements are carried out in which the measurement object (the calibration item) is compared with the values ​​of higher-quality and traceable standards according to a documented procedure. The aim is to identify and document deviations.
Using the example of an Optical Emission Spectrometer, this means that the value of a reference sample (known with a certified uncertainty) is displayed under documented conditions and compared with the certified value. The measurement deviation, i.e. the difference between the measurement object and the standard, is determined as the result.

The expanded measurement uncertainty is specified for each measuring point. With this definition of the term, the original task of calibration laboratories is defined, to which all further services follow.

Difference between factory calibration and DAkkS calibration

Basicly, the TAZ Servicetechnik does not distinguish between DAkkS accredited or factory calibration in the measurement methods and procedures. The procedures do not differ in scope, type or diligence.

The main difference, however, lies in the recognition of the calibration certificates. Factory calibration is subject to the laboratory’s commitment to traceability, best laboratory practice, expert calculation of measurement uncertainty and compliance to DIN EN ISO/IEC 17025. DAkkS-accredited calibration certificates are subject to monitoring by the accreditation body and constant external controls. In addition, these are internationally recognized by the multilateral agreement of the ILAC (MRA) and confirmed as proof of repatriation. The traceability of the measured values ​​contained therein to a national standard does not actually have to be specified in detail, this is guaranteed by the accreditation itself. Form, structure and content are defined by the accreditation body, regularly monitored and thus ensure international compliance with the contents of DIN EN ISO/IEC 17025:2018-03. In both cases, the selection of the measuring points (if available) is defined on the basis of national guidelines or DKD guidelines or by the customer or specified by the calibration laboratory within the framework of the rules of technology.