This lesson explains control valve selection factors and demonstrates typical linear and rotary control valve functions and applications. Control valve bodies for several types of valves including globe, butterfly, and ball valves are described. The function and components of valve trim, including the relationship between flow characteristic and trim type is explained. This lesson trains participants to recognize, identify, and understand actuators and positioners as they relate to control valve trim. The parts and operation of diaphragm and piston actuators as well as pneumatic and electro pneumatic positioners are demonstrated.