Control Valve Sizing and Its Importance

1. ControlValveSizingandIts Importance FromthePerspectiveofControlValveEngineering Consultants Control valvesarecrucialinmanagingtheflow,pressure, temperature, or other variables of the fluid (gas, steam, water, or chemical) in order to account for load fluctuations and keep the process variable as close as possible to the intended set point. Control valvescomeinavarietyoftypes,suchasglobe,ball,andbutterfly. Usually, the application, prior experience, or plant preferences will determinethetypeofcontrolvalve.According to leadingcontrolvalve engineeringconsultants,selectingtherightvalveisquitetricky. However,the sizingofthecontrolvalveistrickier. In this blog, we are going to explain the consideration for control valve sizingandwhyitisimportant. HowAreControlValvesSized?

2. While sizing a control valve, the general approach is to follow the thumb rule. You need to size it in such a way that it operates between 20-80 percent open at the maximum required flow rate and wherever possible.Makesurethatitis notmuchlessthan20 percentopen at the minimum required flow rate. The goal is to make use of as much of the valve's control range as you can while still ensuring an acceptable level of safety. • WhyIsSizing aControlValveImportant? • A control valve that is too small won't be able to pass the necessary flow.However,acontrolvalveis frequentlytoobigforthe application. An oversizedvalveisextremelysensitivetoitsenvironment. • Significantvariationsinflowcanresult fromeventhetiniest • adjustments to the valve position. Due to this, it is challenging or perhaps impossible for the control valve to precisely adjust to the necessaryflow. • According to David Moras, an expert control valve engineering consultantfrom SAROM GLOBAL, “choosing a properly measured and sized control valve is extremely crucial for achieving the highest degreeofcontrol forgas,liquid,ormulti-phasefluidrelated • industries”. • Follow these guidelinesforaccuratecontrolvalve selection andsizing: • A valve'sflowcharacteristicsareprobablyoffif asetofloop tuning • parametersonlyworks atone endofthe controlrange andnot the other.Makesureitisproperlyset. • Usean"equalpercentage"controlvalvewhenthepressure differentialacrossthe valvediminishes as flowrate increases,andin controlloopswheretheprocessgaindropsasflowrateincreases.A "linear"controlvalveis advisedif noneoftheseconditionsapplies. • The control valve should be sized to function between 20 and 80 per cent open at the maximum needed flow and no less than 20 per cent open attheminimumneededflowforthebest control.However,

3. pleasebeawarethat thisisn't alwaysthecaseforalltypesofcontrol valvesanddepends on the valve's flowvs.opencharacteristics. • properlysizedsegmentballs,fullballs,andhigh-performing butterflyvalvesaretypicallytwo sizessmallerthantheline. • properlysizedglobevalvesareone sizesmallerthantheline. • Wheneverselectingorsizingcontrolvalvesforindustrialapplications, itisbestrecommendedtoconfer withexpertcontrolvalve engineeringconsultants.Onlyprofessionalsarecapableofaccessing and analysing the application to select the right choice of valves (includingthesize)thatmeetsthepurpose. • References:https://medium.com/@saromglobal/control-valve-sizing-and-its-importance- b9421c4baa50 • SaromGlobal • HQAustralia,supporting EMEA(Europe,MiddleEast,Africa),AsiaPacific,Americas. • https://www.saromglobal.com/ info@saromglobal.com 61283175089