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The blue valve body is visible in-line with the pipe. The valve actuator opens or closes the butterfly disc of the valve based on electrical signals sent to the actuator. Another valve actuator is visible in the background, with windows to indicate the valve position. A valve actuator is the mechanism for opening and closing a valve. Manually ...
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.
Control valves are normally fitted with actuators and positioners. Pneumatically-actuated globe valves and diaphragm valves are widely used for control purposes in many industries, although quarter-turn types such as (modified) ball and butterfly valves are also used. Control valves can also work with hydraulic actuators (also known as ...
An actuator can be just a mechanism that is directly driven by the motions or forces of other parts of the system. An example is the camshafts that drive the intake and exhaust valves in internal combustion engines, driven by the engine itself.
The wafer style butterfly valve is designed to maintain a seal against bi-directional pressure differential to prevent any backflow in systems designed for unidirectional flow.
Electric rotary valve actuator controlling a butterfly valve. A rotary actuator is an actuator that produces a rotary motion or torque. The simplest actuator is purely mechanical, where linear motion in one direction gives rise to rotation.
A hydraulic cylinder (also called a linear hydraulic motor) is a mechanical actuator that is used to give a unidirectional force through a unidirectional stroke. [citation needed] It has many applications, notably in construction equipment (engineering vehicles), manufacturing machinery, elevators, and civil engineering.
Electrohydraulic servo valves may consist of one or more stages. A single-stage servo valve uses a torque motor to directly position a spool valve. Single-stage servo valves suffer from limitations in flow capability and stability due to torque motor power requirements.