Trim: Trim is a matched pair of ‘plug’ and ‘seat’
CV: The number of U.S. gallons per minute of 60_F water that will flow through a fully open valve with a one pound per square inch pressure drop.
Actuator: The drive unit having a diaphragm and a piston that operates the valve stem.
Stem travel: The scale that shows the stem movement in inches or centimeter.
Valve body: The bottom portion of a control valve installed on a pipeline to control a process. The valve body contains a trim, pipe flange, bonnet, gaskets, guide bush, gland packing, lantern ring, grease, cooling fins…etc.
Yoke: A portion of the actuator which connects the actuator to the valve body carrying a stem travel plate.
Gland packing: A sealing system in the valve body which prevents the process fluid coming out through the valve stem.