Would like to know the difference between installed and Inherent characteristics for a given valve. A specific example would be really useful.
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Inherent flow characteristics refers to the charesteristics observed during flow with a constant pressure drop across the valves. Installed flow characteristics refers to the characteristics of obtained in service when the pressure drop varies with flow and other changes in the system.
Valve manufacturer flow characteristics are generally inherent characteristics, which is determined by testing the valve flow verses valve lift using a constant differencial pressure drop accross the valve throughout the test, thesefore, the manufacturer's trim characteristics should not be confused with the installed flow characteristics in the actual process fluid flow conditions. In actual service, the pressure drop acrros valve varies throughout the valve lift and flow range as a system characteristics.