IEC 60534-2-1:20 11包括用于预测可压缩和不可压缩流体通过控制阀的流量的方程。不可压缩流动的方程基于牛顿不可压缩流体的标准流体动力学方程。当遇到非牛顿流体、流体混合物、浆料或液-固输送系统时，它们不打算使用。对于非蒸发的多组分液体混合物，可谨慎使用不可压缩流动的方程。这第二版取消并取代了1998年出版的第一版。本版构成技术修订版。与上一版相比，它包括以下重大技术变更: -相同的基本流动模型，但改变了方程框架，通过引入Δ PSizing的概念来简化标准的使用； -对非湍流校正和计算结果的手段的改变； -作为附件的多级尺寸。

IEC 60534-2-1:2011 includes equations for predicting the flow of compressible and incompressible fluids through control valves. The equations for incompressible flow are based on standard hydrodynamic equations for Newtonian incompressible fluids. They are not intended for use when non-Newtonian fluids, fluid mixtures, slurries or liquid-solid conveyance systems are encountered. The equations for incompressible flow may be used with caution for non-vaporizing multi-component liquid mixtures. This second edition cancels and replaces the first edition published in 1998. This edition constitutes a technical revision. It includes the following significant technical changes with respect to the previous edition:
- the same fundamental flow model, but changes the equation framework to simplify the use of the standard by introducing the notion of Δp_sizing;
- changes to the non-turbulent flow corrections and means of computing results;
- multi-stage sizing as an Annex.