Both OIML and ASTM classify weights according to their tolerance assignment. For example, OIML classifies weights as: E1, E2, F1, F2, M1, M2 and M3. Whereas ASTM International classifies weights as 0, 1, 2, 3, 4, 5, 6, and 7. Each classification have their own tolerance schedule.

The mass calibrations, which are traceable to the International System of Units (SI), are carried out in our 20°C ±0.02°C mechanical clean room. Calibration results are reported in terms of conventional mass as defined by the Organisation internationale de métrologie légale (OIML): “The conventional mass is the value of the result of weighing a body in air is equal to mass of a standard of conventionally chosen density (8000 kg/m3), at a conventionally chosen temperature (20 °C), which balances this body at this reference temperature in air of conventionally chosen density (1.2 kg/m3)”.

Our complete accredited scope may be seen on the National Research Council’s CLAS web site: scope >