Measurement standard of mass

DEFINITION

The kilogram, symbol kg, is the SI unit of mass. It is defined by taking the fixed numerical value of the Planck constant h to be 6.626 070 15×10^–34 when expressed in the unit J s, which is equal to kg m² s^–1, where the metre and the second are defined in terms of c and ∆ν_Cs.

REALISATION OF THE SCALE

In the Estonian national mass measurement standard laboratory the scale is realised in the measuring range of 1 mg to 50 kg by using a set of 1 kg reference weights and precision comparators. 1 kg reference weights are calibrated in the German National Metrology Institute PTB.

See the approved list of national measurement standards.

DEVICES AND POSSIBILITIES

For offering a calibration service automatic comparators AX107H, AX1006 and AX64004; precision scales UMT 5 and AX504 and reference weights are used.

Weights of classes from E2 to F1 with the expansion uncertainty from 2 μg to 15 mg are calibrated in accordance with OIML’s recommendation R111-1.