Control Valve Sizing - CTi Controltech

← Back to document page

3-1Rev. 6/94CONTENTSIntroduction ........................................ ............ 3-1Nomenclature ........................................ ......... 3-1Calculating Cv for Liquids ............................... 3-3Liquid Sizing Examples .................................. 3-7Calculating Cv for Gases. ............................. 3-10Gas Sizing Examples ................................... 3-13Calculating Cv for Two Phase Flow ..............3-15Vapor Pressure Charts ................................ 3A-1Steam Tables ........................................ .......3A-7Fluid Property Correlation Constants ...... ...3A-21Pipe Data ........................................ ........... 3A-29INTRODUCTIONValtek uses a systematic method for selecting bodytypes, sizes, materials, pressure ratings and trim sizesbased on flow Control Valve flow capacity (Cv) is based upon theindustry standard, ANSI/ISA This standardand the corresponding measuring standards containEquations used to predict the flow of compressible andincompressible fluids in Control valves .

than a globe valve. Thus they tend to choke (or cavitate) at smaller pressure drops than globe valves. Liquid Critical Pressure Ratio Factor, F F The liquid critical pressure ratio factor, F F, multiplied by the vapor pressure, predicts the theoretical vena con-tracta pressure at the maximum effective (choked) pressure drop across the valve ...

  Valves, Globe, Globe valves