ISO 6145-7:2009 气体分析 动态容量法制备校准混合气体 第7部分：热质流控制器

标准编号：ISO 6145-7:2009

中文名称：气体分析 动态容量法制备校准混合气体 第7部分：热质流控制器

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：2009-04

标准范围

ISO 6145-7:20 09规定了一种通过使用市售热质量流量控制器从纯气体或其他气体混合物连续生产包含两种或更多种组分的校准气体混合物的方法。如果采用该方法制备校准气体混合物，最佳性能如下:通过将组合标准不确定度乘以覆盖因子k=2获得的相对扩展测量不确定度U不大于2%。如果使用预混合气体代替纯气体，则可以获得低于10-6的摩尔分数。质量流量的测量不是绝对的，流量控制器需要独立校准。该方法的优点是可以在连续的基础上制备大量的气体混合物，并且如果使用适当数量的热质量流量控制器，可以像二元混合物一样容易地制备多组分混合物。

ISO 6145-7:2009 specifies a method for 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.If this method is employed for the preparation of calibration gas mixtures, the optimum performance is as follows: the relative expanded uncertainty of measurement, U, obtained by multiplying the 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^-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 multicomponent mixtures can be prepared as readily as binary mixtures if the appropriate number of thermal mass-flow controllers is utilized.

标准预览图