混合公差是给定组件的认证浓度和所要求的浓度之间的差异。For example, if you order a mixture at a concentration of 100 ppm with a blend tolerance of 5%, then we must produce a product with a certified concentration between 95 and 105 ppm (i.e. [100-95] / 100 = 0.05 or 5% relative) to be in specification. Blend tolerance will vary by the component and concentration you order, and will also be dependent on the manufacturing method used to make the blend.
因此，由于浓度降低，气体混合物变得逐渐变得更加难以混合和分析，因此必须放松规格。Said another way, a higher concentration results in a tighter blend tolerance, higher analytical accuracy, and higher process accuracy (i.e. smaller values), while a lower concentration results in a looser blend tolerance, lower analytical accuracy and lower process accuracy (i.e. larger values). Other factors affect specifications as well, including characteristics of the minor component, the type of balance gas or liquid used, instrument limitations, reference standard accuracy, and the purity of the raw materials used to make the blend.