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The pressure at which the control pilot relieves is the functional set pressure of the PORV. When the pilot valve reaches set pressure it opens and releases the pressure from the dome. The piston is then free to open and the main valve exhausts the system fluid. The control pilot opens either to the main valve exhaust pipe or to atmosphere ...
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. [1]
Air pilot control: converting from air to oil results in locking of the cylinder. Shifting the four-way valve to either extreme position applies the air pilot through the shuttle valve, holding the two air-operated valves open and applying oil under air pressure to the corresponding side of the cylinder. Positioning a manual valve to neutral ...
Simple hydraulic control valves are binary, they are either on or off. Servo valves are different in that they can continuously vary the flow they supply from zero up to their rated maximum flow, or until the output pressure reaches the supplied pressure. More complex servo valves can control other parameters.
A pilot valve is a small valve that controls a limited-flow control feed to a separate piloted valve. Typically, this separate valve controls a high pressure or high flow feed. Pilot valves are useful because they allow a small and easily operated feed to control a much higher pressure or higher flow feed, which would otherwise require a much ...
A safety valve is a valve that acts as a fail-safe. An example of safety valve is a pressure relief valve (PRV), which automatically releases a substance from a boiler, pressure vessel, or other system, when the pressure or temperature exceeds preset limits. Pilot-operated relief valves are a specialized type of pressure safety valve.
Valve actuator. Electric actuator (blue cylinder) on a valve in a power plant. A black handwheel is visible on the actuator, which allows manual positioning of the valve. 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.
An example of a safety system with passive safety components is the containment vessel of a nuclear reactor. The concrete walls and the steel liner of the vessel exhibit passive safety, but require active systems (valves, feedback loops, external instrumentation, control circuits, etc.) which require external power and human operation to function.