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A control valve is a valve used to control fluid flow by varying the size of the flow passage as directed by a signal from a controller. [1] This enables the direct control of flow rate and the consequential control of process quantities such as pressure , temperature , and liquid level.
The most common final control element in the process control industries is the control valve. The control valve manipulates a flowing fluid, such as gas, steam, water, or chemical compounds, to compensate for the load disturbance and keep the regulated process variable as close as possible to the desired set point. [1]
A level control valve or altitude control valve is a type of valve that automatically responds to changes in the height of a liquid in some storage system. A common example is the set of ballcocks in a flush toilet , where each stage of the flush cycle is actuated by the emptying or filling of the tank.
Traditional control valves make it inevitable. As we size a control valve, the K v calculated almost certainly will not match the K v of the nearest appropriate valve. For example, a K v calculation of 4.5 m 3 /h would most likely lead to the selection of a valve with a K v = 6.3 m 3 /h. This means the valve is capable of delivering 40% more ...
Gate valve, mainly for on–off control, with low pressure drop; Globe valve, good for regulating flow. Uses a cylinder movement over a seat; Knife valve, similar to a gate valve, but usually more compact. Often used for slurries or powders on–off control; Needle valve for accurate flow control; Pinch valve, for slurry flow regulation and ...
The four-way valve or four-way cock is a fluid control valve whose body has four ports equally spaced round the valve chamber and the plug has two passages to connect adjacent ports. The plug may be cylindrical or tapered, or a ball.
Instead of a cap, cylinders sometimes have a protective collar or neck ring around the valve assembly which has an opening for access to fit a regulator or other fitting to the valve outlet, and access to operate the valve. Installation of valves for high pressure aluminum alloy cylinders is described in the guidelines: CGA V-11, Guideline for ...
An isolation valve is a valve in a fluid handling system that stops the flow of process media to a given location, usually for maintenance or safety purposes. [1] They can also be used to provide flow logic (selecting one flow path versus another), and to connect external equipment to a system. [2]