90.93 Standard confirmed Dec 17, 2019
ISO
ISO/TC 158 Analysis of gases
International Standard
71.040.40 Chemical analysis
ISO 6145-9:2009 is one of a series of International Standards dealing with various dynamic volumetric methods used for the preparation of calibration gas mixtures. This part specifies a method for continuous production of calibration gas mixtures containing one or more readily condensable components. A relative expanded uncertainty of measurement, U, obtained by multiplying the relative combined standard uncertainty by a coverage factor k = 2, of not greater than ±1 %, can be obtained using this method.
Unlike the methods presented in the other parts of ISO 6145, the method described in this part does not require accurate measurement of flow rates since flow rates do not appear in the equations for calculation of the volume fraction.
Readily condensable gases and vapours commonly become adsorbed on surfaces, and it is therefore difficult to prepare stable calibration gas mixtures of accurately known composition, containing such components, by means of static methods. In addition, these calibration gas mixtures cannot be maintained under a pressure near the saturation limit without the occurrence of condensation. The saturation method can be employed to prepare mixtures of this type.
PUBLISHED
ISO 6145-9:2009
90.93
Standard confirmed
Dec 17, 2019