What are the inherent flow characteristics of control valves?

Inherent characteristics describe the relationship between valve travel and flow at constant pressure drop. Three main types: Linear - equal increment of travel produces equal change in flow (Cv proportional to position). Equal Percentage - equal increment of travel produces equal percentage change in flow (more flow change at higher opening). Quick Opening - large flow change at small opening, then reduced gain (on-off applications). Characteristic is determined by plug/trim design. Equal percentage is most common for process control because it provides consistent loop gain across operating range.