A control valve is a valve used to control media flow by varying the size of the flow passage as directed by a signal from a controller. This enables the direct control of flow rate and the consequential control of process quantities such as pressure, temperature, and media level.

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The opening or closing of automatic control valves is usually done by electrical, hydraulic or pneumatic actuators. Normally with a modulating valve, which can be set to any position between fully open and fully closed, valve positioners are used to ensure the valve attains the desired degree of opening.

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Air-actuated valves are commonly used because of their simplicity, as they only require a compressed air supply, whereas electrically-operated valves require additional cabling and switch gear, and hydraulically-actuated valves required high pressure supply and return lines for the hydraulic fluid. The pneumatic control signals are traditionally based on a pressure range of 3-15psi or more commonly now, an electrical signal of 4-20mA for industry. Electrical control now often includes a "Smart" communication signal superimposed on the 4-20mA control current, such that the health and verification of the valve position can be signalled back to the controller. 

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An automatic control valve consists of three main parts in which each part exist in several types and designs:

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• Valve actuator - which moves the valve's modulating element, such as ball or butterfly.

• Valve positioner - Which ensures the valve has reached the desired degree of opening. This overcomes the problems of friction and wear.

• Valve body - in which the modulating element, a plug, globe, ball or butterfly, is contained

 

One of our strengths at Tyne Valves is our knowledge and capabilities surrounding actuation and control valves. We have the in-house capability of actuating and supplying actuated valves to the customer's direct specification whether the emphasis is on a general control basis or a more finer control requirement.   

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Please get in touch with a member of our team for price and availability.