IEC 60534-2-1:1998

Covers equations suitable for use in sizing industrial process control valves when the flowing media are compressible fluids. The equations are for use with gas or vapour and are not intended for use with multiphase streams.

Deals with a general sizing equation for incompressible fluid flow under installed conditions. Factors are introduced which permit accurate sizing when choked conditions exist due to either cavitation or flashing. Procedures and factors are incorporated to handle installations where the valve is installed between fittings such as reducers, expanders, etc. A Reynolds number factor allows for applications where non-turbulent flow conditions exist caused by low differential pressure and/or high viscosity fluids. Numerical constants are presented permitting the use of three recognized flow coefficients: Av, Kv, and Cv.

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 ?psizing; - changes to the non-turbulent flow corrections and means of computing results; - multi-stage sizing as an Annex. The contents of the corrigendum of April 2015 have been included in this copy.