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Control valves

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basic understanding of control valves …

basic understanding of control valves
working principle of control valves
flow characteristics of control valves

Published in: Devices & Hardware, Business

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  • The actuator accepts a signal from the control system and, in response, moves the valve to a fully-open or fully-closed position, or a more open or a more closed position (depending on whether 'on / off' or 'continuous' control action is used).
  • Transcript

    • 1. 1 Presented by: Syed Waqas Haider Process Engineer
    • 2. Control Valves control conditions (flow, pressure, temperature, and liquid level ) open or close in response to signals received from controllers Controller compare a "setpoint" to a "process variable" (value provided by sensors) 2
    • 3. 3 Control Valves Rotary Motion Butterfly valves Ball vales Plug valves Linear Motion Globe Valves
    • 4. Three main parts Valve's actuator Valve's positioner Valve's body 4
    • 5. The purpose of the valve actuator is to accurately locate the valve plug in a position dictated by the control signal 5
    • 6. Pneumatic Valve Actuators: Adjust the position of the valve by converting air pressure into rotary motion or linear motion. Piston and Diaphragm Actuators are examples of Pneumatic Actuators Electric Valve Actuators: An electric actuator is powered by motor that converts electrical energy to mechanical torque Hydraulic actuator: Consists of a cylinder or fluid motor that uses hydraulic power to facilitate mechanical operation. The mechanical motion gives an output in terms of linear, rotary or oscillatory motion 6 according to their supply
    • 7. Multi-turn actuator gives torque for at least one full revolution Part-turn actuator gives torque for less than one full revolution Linear actuator opens and closes valves that can be operated via linear force--sometimes called rising stem valves 7 according to their movement
    • 8. Positioners are instruments that help improve control by accurately positioning a control valve actuator in response to a control signal Positioners receive an input signal either pneumatically or electronically and provide output power to an actuator 8
    • 9. Some of the mechanisms i. Force Balance Positioners ii. Motion balance Positioners iii. Electronic Positioners 9
    • 10. 10
    • 11. 11
    • 12. 12 Sensor to detect valve position Micro-Processor Error = Position - Signal
    • 13. Valve Bodies 13
    • 14. 14 Quick Opening: Quick open plugs are used for on-off applications designed to produce maximum flow quickly Linear: produces equal changes in flow per unit of valve stroke regardless of plug position, used where valve pressure drop is a major portion of the total system pressure drop Equal Percentage: change in flow per unit of valve stroke is directly proportional to the flow occurring just before the change is made, generally used for pressure control