THERMO GRAVIMETRIC DEVICE WITH MULTICAMERA THERMOSTAT FOR CALIBRATION OF GAS MICROSTREAM SOURCES. PRODUCTIVITY STABILIZATION OF PERMEABLE GAS MICROSTREAM SOURCES
The construction of thermo gravimetric device with multicamera thermostat is described. The use of continuous-periodical method of gravimetric calibration of gas microstream sources enabled to enhance calibration accuracy and to develop the method of their productivity stabilization. Preparation method of dynamic gas mixtures with the usage of microstream sources (MS) of aggressive substances is the most perspective from the point of view of long-term reproducibility of the set concentration. The main advantage of MS made of fluorine-containing polymers is their use duration and easy moving. At the same time long-term productivity decrease of MS limits their usage as reference standards during international checking. Thermo gravimetric device(TGU-2) designed in ''DYNAGAS' company with multicamera thermostat for MS calibration by continuous-periodic way, enabled to develop the method of decrease of long-term productivity change of organic and inorganic substances (SO<sub>2</sub>< 0.3 %; NO<sub>2</sub>< 1.8 % for a year).