Includes equations for predicting the fow of compressible and incompressible fluids through control valves. Not intended for use when non-Newtonian fluids, fluid mixtures, slurries, or liquid-solid conveyance systems are encoutnererd. Equations for compressible fluids are for use with gas or vapour and are not inteded for use with multiphase streams such as gas-liquid, vapour-liquid or gas-solid mixtures. Valid for valves with xT smaller or equal to 0,84.The contents of the corrigendum of February 2000 have been included in this copy.