Back Pressure Regulator: F sub L

[PuffJr]

I am looking at a table of Cv vs. % Build for back pressure regulators. All values are for F sub L equal to .9 What is F sub L?

 

[JLSeagull]

The factor F sub L is the liquid pressure recovery factor for a control valve. See ISA 75.01.01 for other factors of interest. If working with gas you might be more interested in X sub T, the pressure differental ration factor at choked flow, etc. In addition to buying the ISA standard, you can find the Fisher Control Valve Handbook online for free. Also the control valve vendors provide software to calculate the valve sizing, free. This asumes that they believe that you plan to buy something or influence a purchasing decision.

 

[vpl]

Not an answer to your question (as JLSeagull already answered) but you might want to look at the Process TGML link below. Although it's a bit cumbersome, it does make it possible to write F_L and X_T.

Patricia Lougheed

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