标准号：ISO 6145-7-2001
实施状态：作废
中文名称：气体分析 用动态容量法制备标定用混合气体 第7部分：热质流控制仪
英文名称：Gas analysis - Preparation of calibration gas mixtures using dynamic volumetric methods - Part 7: Thermal mass-flow controllers
发布日期：2001-04
被替代标准：ISO 6145-7-2009
代替标准：ISO/FDIS 6145-7-2000
采用标准：BS ISO 6145-7-2001,IDT;UNE 77243-7-2004,IDT
起草单位：ISO/TC 158
标准简介：This part of ISO 6145 specifies a method for the continuous production of calibration gas mixtures, containing two or more components, from pure gases or other gas mixtures by use of commercially available thermal mass-flow controllers. By adjustment of set-points on flow controllers to pre-determined values, it is possible to change the composition of the gas mixture rapidly and in a continuously variable manner. By selection of appropriate combinations of thermal mass-flow controllers and with use of pure gases, the volume fraction of the component of interest in the complementary gas can be varied by a factor of 1 000. The relative expanded uncertainty of measurement, U, obtained by multiplying the relative combined standard uncertainty by a coverage factor, k = 2, is not greater than 2 %.
If pre-mixed gases are used instead of pure gases, mole fractions below 10<up-6> can be obtained. The measurement of mass flow is not absolute and the flow controller requires independent calibration.
The merits of the method are that a large quantity of the gas mixture can be prepared on a continuous basis and that multi-component mixtures can be prepared as readily as binary mixtures if the appropriate number of thermal mass-flow controllers is utilized.
Gas blending systems, based upon thermal mass-flow controllers, and some including the facility of computerization and automatic control, are commercially available.
文件格式：PDF
文件大小：163.46KB
文件页数：20
（以上信息更新时间为：2019-11-23）
ISO 6145-7-2001 气体分析 用动态容量法制备标定用混合气体 第7部分：热质流控制仪.pdf
(163.46 KB)
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