A high performing software will show where these operating points are on the Cv curve to provide a good assessment of how fit a valve is for the application ’ s primary purpose of flow control . It will also show when the valve is not a good fit , as seen in Figure 4 . Here the minimal flow conditions occur at the start of the valve opening when flow turbulence |
prevents good flow control . The highest quality tools and software will provide an additional assessment of how well the chosen or evaluated valve fits the application , as shown on Figure 5 .
A good tool will also allow the user to extend the assessment of the application
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beyond the one , two or even three operation points . It will provide a simulation of the operation and valve parameters at the full span rather than on discrete operating points , see Figure 6 . Ideally the tool will consider and factor in additional parameters like pressure drop , valve authority , temperature at vena contracta , outlet flow velocity , and others to make recommendations as shown in Figure 7 .
Final Thoughts
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ought to be coupled with sophisticated advanced tools to provide consistent and optimal results . The use of tools and ensuring that criteria are not overlooked will maximize productivity and the reliability of process industry . Automation tools cannot replace the essence of engineering – knowledge , critical thinking , team work , nor can they be a substitute for often intimate manufacturer knowledge of how their valves perform , but it |
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In summary the demographic and business realities of the modern time dictate |
can supplement and help these tasks to reduce variability and increase consis- |
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that expert knowhow and experience |
tency of the positive results . |