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One example of SIS is a temperature sensor that provides a signal to a controller, which compares the sensed process temperature to the desired temperature setpoint and sends a signal to an emergency on-off valve actuator which stops the flow of heating fluid to the process if the process temperature is exceeded by an unsafe margin.
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 ...
An automatic control valve consists of three main parts in which each part exist in several types and designs: 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.
Valves and their types and identifications (e.g. isolation, shutoff, relief and safety valves, valve interlocks) Control inputs and outputs (sensors and final elements, interlocks) Miscellaneous - vents, drains, flanges, special fittings, sampling lines, reducers and swages; Interfaces for class changes; Computer control system
Camless valve trains have long been investigated by several companies, including Renault, BMW, Fiat, Valeo, General Motors, Ricardo, Lotus Engineering who developed electro-hydraulic valve actuation in the late 1980s as a spinoff of their active suspension program (both utilised similar electro-hydraulic actuation and control), Ford, Jiangsu Gongda Power Technologies, and Koenigsegg's sister ...
Control valve with pneumatic diaphragm actuator and "smart" 4–20 mA positioner which will also feed back the actual valve position and status over the current loop The 4–20 mA convention was born in the 1950s out of the earlier highly successful 3–15 psi pneumatic control signal standard, when electronics became cheap and reliable enough ...
The systems evolved, replacing the mechanical linkages to the valves with electrical controls, producing the "fly-by-wire" design, [3] and more recently, optical networking systems called "fly-by-light". All these systems require three separate components, the hydraulic supply system, the valves and associated control network, and the actuators.
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.