ISO 6358-3:2014规定了一种方法，该方法使用简单的数值技术，在不进行测量的情况下，估算具有已知流量特性的部件和管道系统的总体流量特性。 ISO 6358-3:2014中使用的公式描述了可压缩流体通过亚音速和阻塞流部件的行为。 ISO 6358-3:2014还提供了获得流量特性不同于ISO 6358中定义的部件等效流量特性的方法。

ISO 6358-3:2014 specifies a method that uses a simple numerical technique to estimate without measurements the overall flow-rate characteristics of a system of components and piping with known flow-rate characteristics. The formulae used in ISO 6358-3:2014 describe the behaviour of a compressible fluid flow through a component for both subsonic and choked flows. ISO 6358-3:2014 also provides methods to obtain equivalent flow-rate characteristics for components whose flow-rate characteristics differ from those defined in ISO 6358.