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Unlike a ball valve, the disc is always present within the flow, so it induces a pressure drop, even when open. A butterfly valve is from a family of valves called quarter-turn valves. In operation, the valve is fully open or closed when the disc is rotated a quarter turn. The "butterfly" is a metal disc mounted on a rod. When the valve is ...
Uni-directional & bi-directional PTUs [ edit ] On the Airbus A320, the yellow system may power the green system, but because it is also bi-directional, if the starboard engine fails, the green system can help to power the yellow system by dumping excess power into it via the same mechanism.
The solenoid can be useful for positioning, stopping mid-stroke, or for low velocity actuation; especially in a closed loop control system. A uni-directional solenoid would actuate against an opposing force or a dual solenoid system would be self cycling. The proportional concept is more fully described in SAE publication 860759 (1986).
Rotary valves and piston valves: parts of brass instruments used to change their pitch; Rotolock valve; Rupture disc: a one-time-use replaceable valve for rapid pressure relief, used to protect piping systems from excessive pressure or vacuum; more reliable than a safety valve; Saddle valve: where allowed, is used to tap a pipe for a low-flow need
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.).
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.
Globe valve. A globe valve, different from ball valve, is a type of valve used for regulating flow in a pipeline, consisting of a movable plug or disc element and a stationary ring seat in a generally spherical body. [1] Globe valves are named for their spherical body shape with the two halves of the body being separated by an internal baffle.
A complete switching element is usually referred to as a valve, irrespective of its construction. Normally, two valves in the bridge are conducting at any time: one to a phase on the top row and one (from a different phase) on the bottom row. The two conducting valves connect two of the three AC phase voltages, in series, to the DC terminals.