Ensuring metrological traceability of reference materials of gas mixtures composition

The modern concept of metrological assurance for gas analytical measuring instruments with the use of reference materials of gas mixtures composition in cylinders under pressure is presented. The reference materials of gas mixtures composition of approved type in cylinders under pressure, which are the most often means of mole fraction and mass concentration units transfer in gas analytical measurements, are considered. The certified value in these reference materials is the content of the target component (or components) in the gas medium (analytical matrix). All the produced reference materials of gas mixtures composition, which are used for ensuring the uniformity of measurements are traceable to the State primary standard of units of mole fraction, mass fraction and mass concentration of components in gas and gas condensate media GET 154-2019, which characteristics are confirmed on the international level by the results of about 90 international comparisons. The paper presents a methodology for ensuring metrological traceability of reference materials of gas mixtures composition using GET 154-2019, taking into account the constantly increasing park of gas analytical instruments and the emergence of new measuring tasks in various fields of industry and environmental control. Currently, a park of secondary and working standards has been created at enterprises producing reference materials of gas mixtures composition, and their traceability to GET 154-2019 has been implemented according to the state verification scheme. The paper presents the results of international comparisons with participation of GET 154-2019, confirming the comparability of the obtained and reference value of the target component content in reference gas mixtures at the international level. The variety and large number of relevant gas analytical measurement tasks in various industries and the social sphere determines the need to choose priority areas for improving the existing reference base, including the structure of the GET 154 Standard and the nomenclature of reference gas mixtures. The strategic program of the Gas Analysis working group of the Consultative Committee of the Amount of Substance of the International Bureau of Weights and Measures developed for the period up to 2030 has been analysed and a review of the long-term tasks of gas analytical measurements is given. The currently existing GET 154-2019 Standard of the latest generation provides reproduction, storage and transfer of the components’ mole fraction units in gas and gas condensate media in the range from 1.5·10 –8 to 99.99999 %, and mass concentration units in the range from 1.0·10–6 to 2.0·105 mg/m3, what is confirmed by the results of participation in international comparisons and published CMC positions in the International database of calibration and measurement capabilities (about 400 CMCs positions).