NF ISO 6142-2, X20-542-2 (02/2024)

This document describes the static gravimetric preparation of gas mixtures for Class II calibration and describes a method for calculating the measurement uncertainty associated with the mole fraction of each constituent. In addition to all contributions to measurement uncertainty mentioned in ISO 6142-1, this document also takes into account the uncertainty due to the validation process for Class II mixtures that are not individually verified, such as this is the case for Class I mixtures. This document extends the uncertainty assessment described in ISO 6142-1 to include the effects of batch production and the verification process. It provides recommendations on how to obtain an uncertainty budget representative of a particular category of mixtures. Methods for batch production of more than one mixture in a single process are included in this document. This document applies only to mixtures of gaseous or fully vaporized constituents which can be introduced into the bottle in the gaseous or liquid state. Binary and multi-constituent gas mixtures are covered by this document. This document is limited to non-reactive molecules/constituents that are present in quantities greater than or equal to a mole fraction of 100 µmol/mol. This document excludes constituents which react with each other, or with common contaminants such as water vapor or oxygen, or which react with the internal surface of the bottle and the valve in the form of absorption or adsorption .
(Automatic translation from French)