ISO 6145是一系列涉及用于制备校准气体混合物的各种动态方法的文件。本文件规定了一种通过使用热质量流量控制器从标称纯气体或气体混合物连续制备校准气体混合物的方法。该方法适用于制备非反应物质的混合物，即不与热质量流量控制器或辅助设备中的流动路径的任何构造材料反应的那些。 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，摩尔分数低于10？可得6。质量流量的测量不是绝对的，流量控制器需要独立校准。 该方法的优点在于，可以在连续的基础上制备大量的校准气体混合物，并且如果使用适当数量的热质量流量控制器，则可以像二元混合物一样容易地制备多组分混合物。 注:基于热质量流量控制器的气体混合系统以及一些包括计算机化和自动控制设施的系统是市售的。

ISO 6145 is a series of documents dealing with various dynamic methods used for the preparation of calibration gas mixtures. This document specifies a method for continuous preparation of calibration gas mixtures, from nominally pure gases or gas mixtures by use of thermal mass-flow controllers. The method is applicable to preparation of mixtures of non-reacting species, i.e. those which do not react with any material of construction of the flow path in the thermal mass-flow controller or the ancillary equipment. If this method is employed for preparation of calibration gas mixtures the optimum performance is as follows: the relative expanded measurement uncertainty U, obtained by multiplying the 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 calibration 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. NOTE Gas blending systems, based upon thermal mass-flow controllers, and some including the facility of computerization and automatic control, are commercially available.