Control valve sizing is big business. Often there is a thin line between getting it right or wrong with unintended consequences for the process where the control valve is applied. Typically these days, most control valve sizing is done via software supplied by valve manufacturers. However, here the sizing chart presented is a guide for quickly selecting the type of valve required for general-purpose applications before getting down to the nitty-gritty of using a sizing software. As you examine this selection chart, please be reminded that there are so many special circumstances applicable to many control valve applications that the guide provided here be considered as a very approximate first level guide only.
Before using this chart, make sure you understand the terms, P1, P2 and T1 as defined in the schematic for a control valve in a process shown below:
Given that you already understand the control valve schematic illustrated above, you can now carefully examine the valve selection chart below: