Pump Affinity Law - Flow & Head

Flow ∝ N; Head ∝ N²; Power ∝ N³ for a given pump with speed change (or geometrically similar impeller-diameter change).

PumpsAffinity

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Formula, assumptions, and limits

\frac{Q_2}{Q_1} = \frac{N_2}{N_1}, \quad \frac{H_2}{H_1} = \left(\frac{N_2}{N_1}\right)^2, \quad \frac{P_2}{P_1} = \left(\frac{N_2}{N_1}\right)^3

Source: Hydraulic Institute Affinity Laws

Flow \u221d N; Head \u221d N\u00b2; Power \u221d N\u00b3 for a given pump with speed change (or geometrically similar impeller-diameter change).