BS EN ISO 6145-8:2008

BS EN ISO 6145-8:2008 Gas analysis. Preparation of calibration gas mixtures using dynamic volumetric methods. Diffusion method BS EN ISO 6145-8 specifies a dynamic method for the preparation of calibration gas mixtures using diffusion. It covers calibration gas mixtures containing component mole fractions ranging from 10−9 to 10−3. The method specified in BS EN ISO 6145-8 also provides a relative expanded uncertainty of measurement. The method can be applied for the generation of low-concentration calibration gases of organic components that are liquid at room temperature, with boiling points ranging from about 40 °C to 160 °C. BS EN ISO 6145-8 applies to the generation of calibration gas mixtures of a wide range of hydrocarbons at ambient and indoor air concentration levels. It also applies to the generation of low-concentration gas mixtures of water. Contents of BS EN ISO 6145-8 Introduction Scope Normative references Principle Reagents and materials Apparatus Procedure Preliminary checks and operating conditions Determination of mass loss Expression of results Calculation Sources of uncertainty Practical example of a diffusion cell calibrator configured for evaluating speed of response in a hygrometer Example of performances of diffusion cells for toluene and trichloromethane Example of uncertainty calculations for a periodic weighing system