An inherent flow characteristic is the relation between valve opening and flow under constant pressure conditions.
The inherent characteristic of a valve is obtained when there is a constant pressure drop across the valve for all valve positions; the process fluid is not flashing, cavitating or approaching sonic velocity (choked flow); and the actuator is linear (valve stem travel is proportional to the controller output).
Some valves have inherent characteristics that cannot be changed, such as full port ball valves and butterfly valves.
For other valve types, such as the globe type, the inherent characteristics can be changed to suit the application.