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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.
Fittings allow multiple pipes to be connected to cover longer distances, increase or decrease the size of the pipe or tube, or extend a network by branching, and make possible more complex systems than could be achieved with only individual pipes. Valves are specialized fittings that permit regulating the flow of fluid within a plumbing system.
Double pipe heat exchanger Fixed straight tubes heat exchanger: U-shaped tubes heat exchanger Spiral heat exchanger Covered gas vent Curved gas vent Air filter: Funnel or tundish: Steam trap: Viewing glass Pressure reducing valve: Valve: Gate valve: Control valve: Manual valve Check valve: Needle valve: Butterfly valve: Diaphragm valve: Ball ...
Thus the flow rate of the straight pipe is greater than that of the vertical one. Furthermore, because the lower energy fluid in the boundary layer branches through the channels the higher energy fluid in the pipe centre remains in the pipe as shown in Fig. 4. Fig. 4. Velocity profile along a manifold
A relief valve DN25 on cooling water pipe from heat exchanger Schematic diagram of a conventional spring-loaded pressure relief valve. A relief valve or pressure relief valve (PRV) is a type of safety valve used to control or limit the pressure in a system; excessive pressure might otherwise build up and create a process upset, instrument or equipment failure, explosion, or fire.
If the fluid is a liquid, a different type of limiting condition (also known as choked flow) occurs when the venturi effect acting on the liquid flow through the restriction causes a decrease of the liquid pressure beyond the restriction to below that of the liquid's vapor pressure at the prevailing liquid temperature.
The basic principle behind partial stroke testing is that the valve is moved to a predetermined position in order to determine the performance of the shut down valve. This led to the adaptation of pneumatic positioners used on flow control valve for use in partial stroke testing.
The ratio of length to radius of a pipe should be greater than 1/48 of the Reynolds number for the Hagen–Poiseuille law to be valid. [9] If the pipe is too short, the Hagen–Poiseuille equation may result in unphysically high flow rates; the flow is bounded by Bernoulli's principle, under less restrictive conditions, by