The DAkkS calibration certificate for weights

The DAkkS calibration certificate covers the following points:

• The object of calibration.
• The material and density.This is needed to calculate the conventional weight value.
• The ambient conditions at the time of measurement.
• Temperature, atmospheric pressure and relative humidity.
• Traceability to the national standard.
• The conventional weight value with deviation from the nominal value.
• The measurement uncertainty for weighing. This indicates the measuring accuracy. Weighing with absolute accuracy, entirely free of error, is not physically possible.
• The assignment of the weight to an appropriate error limit class. This is based on the legal measurements of the Organisation International de Métrologie Légale (OIML): E1, E2, F1, F2, M1, M2, M3. ­

The respective error limits (= weight tolerances) are graduated at a ratio of 1:3 with E1 being the most accurate and M3 the least accurate class.

Validity period

The metrological properties of a weight noted on a DAkkS calibration certificate are affected by wear over time. However, this depends on the individual weight and how often it is used. A quality officer determines the recalibration periods.