气体分析.用动态容积法标定气体混合物的准备.第10部分:渗透法

[中文适用范围]： ISO 6145 的这一部分规定了一种使用渗透膜制备成分摩尔分数范围为 10 到 10 的校准气体混合物的动态方法。 使用该方法可以实现成分摩尔分数 2.5% 的相对扩展不确定度。 在所考虑的摩尔分数范围内，很难将某些气体混合物（例如在钢瓶中）维持在稳定状态。 因此，需要在使用前立即制备校准气体，并通过尽可能短的路径将其传输到要使用的地方。 该技术已成功应用于生成空气中二氧化硫 (SO2)、二氧化氮 (NO2) 和苯 (C6H6) 等低含量校准气体混合物。 如果载气流量作为气体质量流量进行测量，则使用渗透管制备校准气体混合物是一种动态重量分析方法，该方法给出摩尔分数的含量。 [外文原描述]： 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.