ISO 6145-9:2009 PDF
Gas analysis — Preparation of calibration gas mixtures using dynamic volumetric methods — Part 9: Saturation method
Gas analysis — Preparation of calibration gas mixtures using dynamic volumetric methods — Part 9: Saturation method
- Статус документа:
- Действующий
- Формат:
- Электронный (PDF)
- Количество страниц:
- 14
- Дата публикации:
- 29 сентября 2009 г.
- Издание:
- ISO IS 6145 edition 2 version 1
- ICS:
- 71.040.40
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.
Abstract
Overview
ISO 6145-9:2009 - Gas analysis: Saturation method specifies a dynamic volumetric technique for the continuous preparation of calibration gas mixtures that contain one or more readily condensable components (gases or vapours). The standard describes equipment, operating procedures and uncertainty evaluation for producing stable calibration mixtures using the saturation principle (vapour in equilibrium with its condensed phase). The method can achieve a relative expanded uncertainty (k = 2) of not greater than ±1 % in volume fraction, and - unlike many other dynamic methods - does not require accurate flow-rate measurement because flow rates do not appear in the calculation equations.
Key topics and technical requirements
- Principle: Volume fraction ≈ vapour pressure of component at condenser temperature divided by total pressure in the condenser. Vapour pressure is taken from established tables/diagrams.
- Equipment: saturator, condenser (good thermal conductivity), pressure-equalizing vessel with baffles, condensate receiver, filters, accurate temperature control and pressure measurement, optional closed-loop circulation and pump.
- Temperature & pressure control:
- Temperature stability and measurement critical - thermometers with error
Технические детали
- Технический комитет
- ISO/TC 158 - Analysis of gases
- SKU
- ISO 6145-9:2009
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