TABLE OF CONTENTS This chapter is an introduction to actuators and actuator control and will help you understand the operation of control devices and their use in flow control.
Topics covered in this chapter are as follows:
The operation and use of various types of self-regulating devices and loading used in gas regulators
Closed loop pneumatic, hydraulic, and electrical liquid flow valves
Fail-safe operation in valves
The various types of valves in use
Valve characteristics
Electronic power control devices
Methods of applying feedback for position control
Relays and motors for actuator control
This section deals with control devices used for regulating temperature, pressure, controlling liquid, and gas flow in industrial processing. The devices can be self-regulating or under the control of a central processing system that can be monitoring and controlling many variables.
This section will discuss actuators and regulators and their use for the control of gas flow, liquid flow, and pressure control. In many processes this involves the control of many thousands of cubic meters of a liquid or the control of large forces, as would be the case in a steel rolling mill from low-level analog, digital, or pneumatic signals. Temperature can also normally be controlled by regulating gas and/or liquid flow. Control loops can be local self-regulating loops under pneumatic, hydraulic, or electrical control, or the loops can be processor controlled with additional position feedback loops. Electrical signals from a controller are low-level signals that require the use of relays for power control or amplification...
