May I ask everyone about the selection process for control valves?
Thread Content
I would like to ask everyone: when selecting a control valve, is it necessary to calculate the flow coefficient Cv value, the valve diameter C value, and the adjustable ratio R value? ?
Generally, the size of the valve should match that of the pipeline. The CV is calculated using process parameters, and it is determined based on the rated CV value. If both the CV and the degree of opening meet the requirements, then the rated CV of this control valve is the one you have chosen
When selecting control valves, it is necessary to calculate the flow coefficient Cv value; however, this is generally determined based on process considerations, with instruments rarely being used for such calculations
It seems that what was said above is the exact opposite: the CV value is calculated by the instrument, while the process is not taken into account. However, the required parameters such as temperature, pressure, flow rate, and specific gravity are provided by the process.
Generally, the actual CV value is calculated based on the actual operating conditions, and then an appropriate diameter can be selected by comparing it with the valve’s rated CV value.
What needs to be calculated is usually handled by the instrumentation team; the calculation formulas vary for liquids, gases, and vapors. It is also necessary to determine whether there is flow obstruction, flash vaporization, or cavitation, among other things