Calibration and metrological traceability are technical terms that are not always easy to understand. They are key concepts for understanding the validity of certificates.
What is calibration?
Calibration or calibration, is an operation which, under certain conditions, first establishes the relationship between the values of a quantity and the measurement uncertainties given by standards and corresponding indications with their associated measurement uncertainties, and then uses this information to establish a relationship which, on the basis of the indication, gives a measurement result (source: SIST-V ISO/IEC Guide 99).
In other words: calibration is a set of operations to establish the difference between the reading of a measuring system and a reference value realised with standards or reference material. Calibration determines the error of your measuring system (instrument, sensor, indicator, etc.).
What does calibration guarantee?
Calibration ensures traceability of the results. The calibration provides the user with trustworthy information about the error of their measurement system. By taking into account the calibration results, the user is able to ensure their own quality requirements, which often follow quality, sustainability and energy efficiency requirements.
What is metrological traceability?
It is a property of a measurement result that allows the result to be related to a reference through a documented continuous chain of measurements, each of which contributes to the measurement uncertainty (source: SIST-V ISO/IEC Guide 99).
Metrological traceability means that all standards or measuring instruments that directly or indirectly affect the result of a calibration are traceable to the SI system through an unbroken chain of comparisons.
Metrological traceability is ensured by calibration. Calibration laboratories that meet the requirements of SIST EN ISO/IEC 17025 shall be considered as qualified and competent to perform calibrations. A calibration certificate issued by an accredited calibration laboratory (accredited by one of the listed accreditation organisations of the MLA or bilateral signatories) is sufficient proof of measurement traceability. In the case of accredited calibration laboratories, calibration certificates bearing the logo of the accreditation body, or a reference to accreditation that clearly indicates that the calibration was performed in the context of an accredited activity, are considered to be relevant (source Slovenian Accreditation, Guideline OA02).
In Slovenia, accreditation is carried out by Slovenian Accreditation (SA), which is a signatory to the Mutual Recognition Agreement (MRA). This means that a product for which there is an accredited report or accredited certificate does not need to be retested, inspected or calibrated in the signatory countries. Of course, the accredited report or certificate must bear the accreditation mark or refer to the accreditation status by means of a declaration.