BASIC OPERATION AND FUNCTION OF CONTROL VALVES

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BASICBASICOPERATIONOPERATIONANDANDFUNCTI ONFUNCTIONOFOFCONTROLCONTROLVALVESVALVES 02-99- 2 -That valvedrives me crazy!??What ishappening insidethat valve??Gaskets Won't Seal!Unusually HighTrim Maintenance!!Packing Always Leaks!NOISY!!VIBRATING!!Positioner AlwaysNeeds Calibration!Too much seat leakage!LOUSY CONTROL !RATTLING!Table of ContentsTOPIC - SUBJECTSECTIONTerminology--------------- ---------------------------------------- ------- 1Control Valve BASIC Designs --------------------------------------- 2Characterization and Trim Design -------------------------------- 3Control Valve Technical Considerations ----------------------- 4Force-Balance Principle ---------------------------------------- ----- 5Actuator BASIC Designs ---------------------------------------- ------ 6Control Valve Unit Action ---------------------------------------- --- 7Actuator Benchset Range ---------------------------------------- --- 8Valve Positioner Basics ---------------------------------------- ------ 9Control Loop Action ---------------------------------------- ---------- 10Control Valve Packing Designs ----------------------------------- 11Seat Leakage ---------------------------------------- -------------------- 12- 3 -SECTION

valves. liquid pressure recovery factor: The ratio (FL) of the valve flow coefficient (Cv) based on the pressure drop at the vena contracta, to the usual valve flow coefficient (Cv) which is based on the overall pressure drop across the valve in non-vaporizing liquid service. These coefficients compare with the orifice metering

  Pressure, Valves