The meaning of the term “calibration” and its purpose are straightforward: Calibration is the comparison of obtained measurement results with a standard reference value. In the case of density calibrations, the standard reference value is, for instance, given by the certificate of liquid density standards and informs whether the instrument results are accurate.
What is calibration?
When is a calibration traceable?
A calibration is traceable when the performed measurement is directly linked to the respective national standard by a consistent measurement chain. Traceable calibrations mean international comparability of results obtained with a calibrated instrument.
This can be illustrated with an example from international trade: The prerequisite of international comparability is the traceability to national standards. A pharmaceutical company, for example, can be sure that the composition of an infusion solution, such as a binary salt solution, is identical in every single production site worldwide if the company’s calibrated density meters give identical results. This perhaps justifies the investment required when placing an order for calibrating a new or already existing density meter.
What is ISO?
ISO is the International Organization for Standardization. It develops and publishes international standards but does not issue certifications. Certification may only be provided by independent and external certification bodies.
The ISO standard ISO/IEC 17025 “General requirements for the competence of testing and calibration laboratories” is the international reference for laboratories carrying out calibration and testing activities around the world.
What does a calibration involve?
An ISO 17025 calibration for density meters, for example, includes an initial thorough cleaning followed by a temperature and a density adjustment to ensure optimal calibration results.