Reference thermogravimetric complex (TGC) for calibration of gas microstream sources and dynamic preparation of gas mixtures with traceable parameters. The defining of the reason of long-term change in productivity of gas (vapor) microstream sources

The preparation method of dynamic gas mixtures using micro stream sources (MS) of aggressive substances is the most perspective, from the point of view of long-term reproduceability of the preset concentration. The main advantage of MS, made of fluorinecontaining polymers, is the possibility to use in them a wide range of compounds nomenclature, including condensed gases, liquids, sublimated solids and many semi-volatile organic compounds. Using of MS for dynamic gas mixtures preparation on the Thermogravimetric complexes allows to calculate concentration on base of the direct mass measurements of traceable components - substance microg / nitrogen mg (taking in account the analyte purity). In this paper we consider the Thermogravimetric complex developed in "DINAGAS" company for dynamic gas mixtures preparation based on the electronic balance SARTORIUS, with high-precision vertical thermostat for MS and mass calibrator of the dilution gas flow-rate, in which liquefied nitrogen is used. The developed complex allowed to carry out the research of fluoroplastic (PTFE) tubes used for the production of gas-permeable housing, as a result- this research confirmed the presence of water vapor in pores of permeable walls. This presence has a significant impact both on the magnitude of their produce ability, as well on their long-term stability.