Control Valve PPT

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 A control valve is a valve that regulates fluid flow by changing the size of the flow passage in response to a controller signal.  This allows for direct control of flow rate and, as a result, process variables including pressure, temperature, and liquid level. Electrical, hydraulic, or pneumatic actuators are commonly used to open or close automatic control valves. Valve positioners are typically used with modulating valves, which can be set to any position between fully open and totally closed, to ensure the valve achieves the required degree of opening.

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Air-actuated valves are often employed due to their simplicity, as they simply require compressed air, whereas electrically-operated valves require additional cabling and switch gear, and hydraulically-actuated valves necessitate high-pressure hydraulic fluid supply and return lines.

An automatic control valve is made up of three basic sections, each of which comes in a variety of styles and designs:

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The valve actuator, such as a ball or butterfly valve, moves the valve's modulating element.

Valve positioner - This device guarantees that the valve has opened to the proper degree. Friction and wear issues are no longer an issue.

The modulating element, such as a plug, globe, ball, or butterfly, is housed in the valve body.

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