National measurement standards / National Metrology Institute

Metrosert is the National Metrology Institute of Estonia. We maintain and develop Estonian national measurement standards for length, mass, temperature and electrical quantities. The quality of numerous Estonian products and services is based on our measuring capability.



The kelvin, symbol K, is the SI unit of thermodynamic temperature. It is defined by taking the fixed numerical value of the Boltzmann constant k to be 1.380 649 x 10–23 when expressed in the unit J K–1, which is equal to kg m2 s–2 K–1, where the kilogram, metre and second are defined in terms of h, c and ΔνCs.

The Estonian National Standard Laboratory for Temperature realizes temperature scale in measuring range (-38.8344 to +419.527) °C, using six temperature fixed-point cells (Hg, H20, Ga, In, Sn and Zn) and a group of standard platinum resistance thermometers with two Precision Thermometry Bridges.

Calibration of thermometers is based on international temperature scale of ITS-90 in the temperature range of (-196 to +420) °C with the expanded uncertainty of (1 to 80) mK.

Kristjan Tammik

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