Valve Rangeability
Compute the rangeability (turndown) of a control valve, R = Qmax/Qmin, the ratio of the largest to the smallest flow it controls accurately. A high rangeability (e.g. 50:1) means the valve works well at both high and low flows, offering fine control over a wide range. It is a key criterion in valve selection. Enter the maximum and minimum controllable flows.
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Valve rangeability
A control valve has to regulate flow both when the process asks for a great deal and when it asks for very little. Rangeability (or turndown) measures that versatility: R = Qmax/Qmin, the ratio between the largest and the smallest flow rate the valve controls accurately. A 50:1 valve gives good control from 2% to 100% of the flow; below that minimum it starts working almost closed, where small stem movements cause large swings and control turns unstable. Valves with an equal-percentage characteristic have high rangeability; quick-opening ones have low rangeability. It is a decisive criterion in valve selection, above all in processes with a wide swing in load. Enter the maximum and minimum controllable flow rates.
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The results provided by this tool are for general informational and educational purposes only and do not constitute professional, financial, medical, legal, tax or accounting advice. Always confirm important decisions with a qualified professional and official sources.