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Oxygen and MAPP gas cylinders with two-stage pressure regulators Schematic diagram of pressure reducing regulator (A) and back-pressure regulator (B). The upper diagrams show the normal state for the valves, which is normally open for pressure reducers and normally closed for back-pressure valves.
Valves are actuated by an electric motor, hydraulic fluid or air. 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.
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 ...
Isolation valves can be in the normally open position (NO) or normally closed (NC). Normally open valves are located between pressure vessels, pumps, compressors, tanks, pressure sensors, liquid level measurement instrumentation and other components and allow fluids to flow between components, or to be connected to sensors. [3]
Ordinary valves can have many ports and fluid paths. A 2-way valve, for example, has 2 ports; if the valve is open, then the two ports are connected and fluid may flow between the ports; if the valve is closed, then ports are isolated. If the valve is open when the solenoid is not energized, then the valve is termed normally open (N.O.).
Control valve: Controls flow parameters proportional to an input signal received from the central control system. Examples: Globe valve, angle valve, ball valve; Shut-off / On-off valve: These valves are either completely open or closed. Examples: Gate valve, ball valve, globe valve, angle valve, pinch valve, diaphragm valve
The two lower valves are called the master valves (upper and lower respectively). Master valves are normally in the fully open position and are never opened or closed when the well is flowing (except in an emergency) to prevent erosion of the valve sealing surfaces. The lower master valve will normally be manually operated, while the upper ...
Examples of normally-closed valves are sampling valves, which are only opened while a sample is taken. Other examples of normally-closed valves are emergency shutdown valves, which are kept open when the system is in operation and will automatically shut by taking away the power supply. This happens when there is a problem with a unit or a ...