ISO 6145的本部分规定了使用渗透膜进行校准准备的动态方法 组分摩尔分数在10-9和10-6之间的气体混合物。相对扩展的不确定性 使用该方法可获得2.5%的组分摩尔分数。在所考虑的摩尔分数范围内 很难保持某些气体混合物（例如气瓶中的气体混合物）处于稳定状态。因此，我们希望 使用前立即准备好校准气体，并以尽可能短的路径将其转移到指定位置 在哪里使用。该技术已成功应用于低含量标定气体的生成 空气中二氧化硫（SO2）、二氧化氮（NO2）和苯（C6H6）的混合物。 如果载气流量测量为气体质量流量，则使用渗透法制备校准气体混合物 试管是一种动态重量分析法，以摩尔分数给出含量。

This part of ISO 6145 specifies a dynamic method using permeation membranes for the preparation of calibration gas mixtures containing component mole fractions ranging from 10？9 and 10？6. A relative expanded uncertainty of 2,5 % of the component mole fraction can be achieved using this method. In the mole fraction range considered, it is difficult to maintain some gas mixtures, for example in cylinders, in a stable state. It is therefore desirable to prepare the calibration gas immediately before use, and to transfer it by the shortest possible path to the place where it is to be used. This technique has been successfully applied in generating low content calibration gas mixtures of, for example, sulfur dioxide (SO2), nitrogen dioxide (NO2) and benzene (C6H6) in air. If the carrier gas flow is measured as a gas mass-flow, the preparation of calibration gas mixtures using permeation tubes is a dynamic-gravimetric method which gives contents in mole fractions.