Explain the following on a control valve: 1) Trim 2) CV 3) Actuator 4) Stem travel 5) Valve body 6) Yoke 7) Gland packing

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.

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