Types of Instruments
(1) Sensors
Pressure, Temperature, Flow, Level and analytical.
(2) Actuators:
Flow, Pressure, Temperature and Level.
Control Valve
Process control consists of three instrumentation elements. Measurement, evaluation, and final control. The final control element is probably the most important because it exerts a direct influence on the process. Final control devices contain the essential pieces of equipment to convert the control signal (generated by a process controller) into the action needed to correctly control the process.
Control valve is a final control device. A control valve is simply a variable orifice that is used to regulate the flow of a process fluid according to the requirements of the process.
https://www.youtube.com/watch?v=XDyTPlkwKak Our next Vooklet (Video Booklet) provides a good Idea on control valve operation and instrumentation sensors. See instrumentation fundamental on this page
