Quick information/definition of terms

Weights are used…

… as measurement standards for testing scales
… as measurement standards for testing weights in a lower accuracy class

Material

We use stainless steel, grey cast iron, steel, nickel silver and aluminium, depending on the class.

Conventional weight value

For a weight with a reference temperature of 20 °C, the conventional weight value corresponds to the mass of a measurement standard with a density of 8,000 kg/m³ that it holds in balance in air with a reference density of 1.2 kg/m³.

Magnetism

Compliance with the limit values for polarisation and magnetic susceptibility is assured in advance by choosing the correct materials.

Labelling

Weights are labelled to assign them to a class and nominal value.

OIML

Abbreviation – International Organization of Legal Metrology.

The OIML accuracy classes of the weights are defined as follows:

Class E1	Weights to ensure traceability between the national mass standards (the values of which are derived from the international kilogram prototype) and weights in class E2 and lower. A calibration certificate always has to be included with weights or weight sets in class E1.
Class E2	Weights for the calibration or standardisation of class F1 weights as well as weights for use with scales in accuracy class I. A calibration certificate has to be included with weights or weight sets in class E2. They can be used as class E1 weights if they meet the surface roughness, magnetic susceptibility and magnetisation requirements for class E1 weights and if these data are specified on the calibration certificate.
Class F1	Weights for the calibration or standardisation of class F2 weights as well as weights for use with scales in accuracy class I and II.
Class F2	Weights for the calibration or standardisation of class M1 weights and possibly class M2. Also for use in major commercial transactions (for example, precious metals and gemstones).
Class M1	Weights for the calibration or standardisation of class M2 weights as well as weights for use with scales in accuracy class III.
Class M2	Weights for the calibration or standardisation of class M3 weights as well as weights for use with scales in accuracy class III in general commercial transactions.
Class M3	Weights for use with scales in accuracy class III and IIII.

Error limits

The largest value permitted by national regulations for the difference between the measured conventional weight value and the nominal value of a weight, which was determined with the corresponding measurement standards.
PDF download – list with error limits