Measurement comparisons: A tool to guarantee the reliability of measurement systems and of high-tech industry

Measurement comparisons are the main tool to establish the measurements compatibility between different laboratories or different measurement methods. They are a mean to establish the equivalence of national standards maintained at the National Measurement Institutes (NMIs), the correctness of the measurement traceability transfer from NMIs to secondary calibration laboratories, of their accreditations, the competence of their operators and the suitability of their equipment. ILCs role is then of great importance as the NMIs and the secondary calibration laboratories lay at the top of a chain representing the measurement system of each modern industrialized country. Each step of this chain has to be under control to assure that final products (or product parts) are reliable and so that can eventually be assembled with other parts made in other countries. At international level, high accuracy key comparisons among NMIs serve to compare national standards while at national level, ILCs between NMIs and secondary calibration laboratories serve to verify the capabilities of those laboratories. In their turn, secondary laboratories calibrate the instrumentation of lower level and industrial laboratories. As these last ones support directly the industrial and manufacturing sectors, ILCs are the main tool to assure the reliability of measurement systems and thus represent a fundamental support for high-tech modern industry.