Set-up of Mass Scales above 1 kg Illustrated by the Example of a 5 t Mass Scale

To an ever increasing extent, weighing instruments for the determination of masses of more than 50 kg are designed as high-accuracy weighing instruments of accuracy class II rather than as medium accuracy weighing instruments of accuracy class III. Consequently, the masses required for testing must meet higher accuracy requirements. The uncertainty of a 5 t mass scale set up at the Physikalisch-Technische Bundesanstalt (PTB) is assessed on the basis of an analysis of the uncertainties which can be attained. This mass scale allows masses of 10 kg, 50 kg, 500 kg and 5 t to be calibrated with relative uncertainties of 5 × 10 -8 , 6 × 10 -8 , 3 × 10 -7 and 1,5 × 10 -7 . With their aid, deadweights of up to 50 kN for force standard machines can be determined with relative uncertainties of 4 × 10 -7 .