control valve engineering job oriented questions

What is mean by CV of control valve?
   
    CV mean valve co-efficient or co-efficient of valve,which can be described as,
 Flow rate of water from inlet to outlet of control valve under the following condition condition

1. Valve open.
2. One PSI pressure on input and output.
3. Water at 60 Fahrenheit

 Unit of CV = US GALLONS/MINUTE.

  What you know about TRIM of control valve?

    All the contacting part of valve body with the process fluid.

                               OR

    All the removable part of valve body.

parts of cv

3D view of  cv