ISO 6145-6:2003 气体分析.标定用混合气体的制备.动态容量法.第6部分：声孔
标准编号：ISO 6145-6:2003
中文名称：气体分析.标定用混合气体的制备.动态容量法.第6部分：声孔
英文名称：Gas analysis — Preparation of calibration gas mixtures using dynamic volumetric methods — Part 6: Critical orifices
发布日期：2003-05
标准范围
ISO 6145-6:20 03规定了一种通过使用临界孔系统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。通过选择适当的孔口组合和使用纯气体，校准气体混合物中校准组分的体积分数可以改变104倍。另外，通过改变孔口系统中的初始压力，它可以改变102倍。该方法的不确定度主要取决于流量校准方法以及温度和出口压力的变化。二元混合物（覆盖率为2）可获得的体积分数的相对扩展不确定度为3%。如果使用预混合气体代替纯气体，则可以获得低得多的体积分数。可以通过ISO 6145-1中给出的合适方法计算和独立测量质量流速或体积流速，由此确定质量或体积分数。该方法的优点是，如果使用适当数量的孔，多组分混合物可以像二元混合物一样容易地制备，并且可以在连续的基础上制备大量的校准气体混合物。流速的范围可以是从几毫升/分钟到大约10L/min。尽管特别适用于在大气压力下制备气体混合物，该方法还提供了在高于大气压力的压力下制备校准气体混合物的方法。
ISO 6145-6:2003 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 critical orifice systems. By selection of appropriate combinations of orifices and with the use of pure gases, the volume fraction of the calibration component in the calibration gas mixture can be varied by a factor of 104. Additionally, it can be changed by a factor of 102 by changing the initial pressures in the orifice systems. The uncertainty of the method depends mainly upon the flow calibration method and the variations in temperature and outlet pressure. The relative expanded uncertainty in the volume fraction obtainable for a binary mixture (at a coverage factor of 2) is 3 %.If pre-mixed gases are used instead of pure gases, much lower volume fractions can be obtained. The mass flow rates or volume flow rates, from which the mass or volume fractions are determined, can be calculated and can be independently measured by a suitable method given in ISO 6145-1.The merits of the method are that multi-component mixtures can be prepared as readily as binary mixtures if the appropriate number of orifices is utilized, and that a large quantity of calibration gas mixture can be prepared on a continuous basis. The range of flow rates can be from several millilitres per minute to approximately 10 l/min.Although particularly applicable to preparation of gas mixtures at barometric pressure, the method also provides a means of preparation of calibration gas mixtures at pressures above barometric pressure.
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