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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.
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.
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 ...
For air-operated control valves, electrical signals from the control system are converted to an air pressure for the valve actuator in a current/pneumatic I/P converter. Upon loss of pneumatic or hydraulic pressure valves may fail to an open (FO) or fail to a closed (FC) position. Some instrumentation is self actuating.
Solenoid valves. A solenoid valve is an electromechanically operated valve.. Solenoid valves differ in the characteristics of the electric current they use, the strength of the magnetic field they generate, the mechanism they use to regulate the fluid, and the type and characteristics of fluid they control.
Partial stroke testing (or PST) is a technique used in a control system to allow the user to test a percentage of the possible failure modes of a shut down valve without the need to physically close the valve.
The IAC actuator is an electrically controlled device, which gets its input from the vehicle's engine control unit (ECU). The actuator is fitted such that it either bypasses the throttle or operates the throttle butterfly valve directly.
Tilting-disc inconel check valve Check valve symbol on piping and instrumentation diagrams.The arrow shows the flow direction. Vertical lift check valve. A check valve, non-return valve, reflux valve, retention valve, foot valve, or one-way valve is a valve that normally allows fluid (liquid or gas) to flow through it in only one direction.