SIudstyr

SIudstyr is a term used in metrology to denote equipment and tools used to realize and disseminate the International System of Units (SI). It covers devices, artifacts, reference materials, and measurement systems that ensure measurements are traceable to SI base and derived units. The purpose is to enable accurate, comparable measurements across laboratories, industries, and borders, supporting science, manufacturing quality, and regulatory compliance.

Typical categories include primary standards (artifacts such as the international kilogram prototype and other length standards), secondary standards, working standards, and calibration equipment; measurement instruments such as balances, interferometers, voltmeters, thermometers, and spectrometers; time and frequency standards (cesium and optical clocks); reference materials; and environmental sensors that are calibrated to SI. Data acquisition and digital measurement systems that display SI-traceable values are also considered SIudstyr when used in measurement contexts.

Operations involve calibration, verification, and maintenance; establishing traceability chains; uncertainty analysis; and documentation through calibration certificates. National metrology institutes (NMIs) and international bodies such as the Bureau International des Poids et Mesures (BIPM) maintain and coordinate SIudstyr programs to harmonize measurement standards worldwide.

In practice, SIudstyr underpins quality management systems, regulatory testing, and scientific experiments by providing consistent references for units such as metre, kilogram, second, ampere, kelvin, mole, and candela, as well as derived quantities.

The term is commonly used in Danish and Norwegian contexts; it emphasizes that equipment is designed, verified, and documented to maintain SI traceability.