Overview

This part of IEC 60534 includes equations for calculating the flow of compressible and incompressible fluids through control valves. The equations for incompressible flow are based on 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 shall be used with particular caution for non-vaporizing multi-component liquid mixtures. At very low ratios of pressure differential to absolute inlet pressure, compressible fluids behave similarly to incompressible fluids. Under such conditions, the sizing equations for compressible flow can be traced to the standard hydrodynamic equations for Newtonian incompressible fluids. However, increasing values regarding the ratio of pressure differential to absolute inlet pressure result in compressibility effects which require that the basic equations be modified by appropriate correction factors. The proposed equations for compressible fluids apply for ideal gases or vapours and are not suitable for use with multiphase streams such as gas-liquid, vapour-liquid or gas-solid mixtures, however. Reasonable accuracy can only be ensured when the specific heat ratio is restricted to the range 1,08 to 1,65. While the equation structure utilized in this document departs radically from previous versions of the standard, the basic technology is relatively unchanged. The revised equation format was selected to simplify presentation of the various equations and improve readability of the document. The responsible committee is K 963 "Stellgeräte für strömende Stoffe" ("Industrial process control valves") of the DKE (German Commission for Electrical, Electronic and Information Technologies) at DIN and VDE.

Document: references other documents

Responsible national committee

DKE/K 963 - Stellgeräte für strömende Stoffe