Selection of valve size


Posted February 12, 2022 by valvelity

An important part of the process of selecting the correct valve size, but there are other equally important considerations, as well.
 
It's a lot more open than just selecting the valve between 60 and 80%! When valve professionals talk about "valve sizing," they really mean selecting a valve that will control the entire process of working optimally for the process. An important part of the process of selecting the correct valve size, but there are other equally important considerations, as well. Valve Size The control valve should be sized so that it operates between 60 and 80 open at the maximum flow rate and as far below 20 percent as possible, without opening the minimum flow required. The idea is to use as much of the valve's control range as possible while maintaining a reasonable, but not excessive, safety factor.

A short valve, obviously, will not pass the required flow. Less obvious is that an oversized valve will operate only a fraction of its total adjustment range. Any stickiness caused by friction will be amplified by an overly sensitive oversized valve, reducing the accuracy of the controlled flow. On the right side of the graph, assuming both valves can be positioned with the same resolution, a properly sized valve (green graph) will be able to control flow at 1 gpm, while an oversized valve (red curve) will only be able to control flow at 1 gpm 2.4 gpm flow control. Applications in cavitating liquids must be evaluated for cavitation. Not only does cavitation cause high levels of noise and vibration, it can cause very rapid damage to valve trim and/or downstream piping. Especially for rotary valves, the prediction of the destructive level of cavitation is more complicated than the simple calculation of choke pressure drop. Due to flow separation and vortex formation within the valve, the reduced pressure and localized regions of recovery can lead to destructive cavitation resulting in complete blockage of flow when the pressure drops below that.


A proven method for predicting cavitation damage of rotary control valves based on the correlation of calculated sound pressure levels and potential damage. Noise In addition, a noisy valve in liquid service will most likely suffer from unacceptable cavitation rates, and high noise levels often cause vibrations that damage piping, instrumentation, and other equipment. Control valves in steam and gas service can produce noise levels well above standard in plants, even at modest pressure drops, especially in sizes above 3 or 4 inches.

https://www.bbvalve.net/product/brass-valve-fitting/compression-fittings/
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Tags bib tap manufacturers , oem custom brass , pex water distribution manifold
Last Updated February 12, 2022