Pressure drop, also known as pressure loss, is an important selection criteria for control valves as it’s used in the sizing calculation. Let’s define the term pressure drop, show how it’s calculated, and discuss why it’s important for engineers designing flow systems. Definition of Pressure Loss Pressure drop is the difference in pressure as measured between two points in a pipe with flowing fluid. For a control valve, the pressure drop is the difference between the inlet pressure and the outlet pressure. It varies with the flow. Calculation of Pressure Loss The calculation for pressure drop looks like this △P=P1 + P2. The pressure drop is usually measured in pounds per…