Calcolatore Leggi di Affinità Pompe — Formula

Pump Affinity Laws

The affinity laws predict how centrifugal pump performance changes with rotational speed or impeller diameter. They are essential for variable-speed pump sizing.

Speed Change Laws

Q2/Q1 = N2/N1 (flow scales linearly)

H2/H1 = (N2/N1)² (head scales with speed squared)

P2/P1 = (N2/N1)³ (power scales with speed cubed)

The same relationships apply for impeller diameter changes (replacing N with D). The cubic power relationship makes VFDs very effective for energy savings.

Esempio Risolto

A pump at 1450 RPM delivers 100 m³/h at 30 m head, consuming 15 kW. Speed increased to 1750 RPM.

  1. Speed ratio = 1750 / 1450 = 1.2069
  2. Q2 = 100 × 1.2069 = 120.7 m³/h
  3. H2 = 30 × 1.2069² = 30 × 1.4566 = 43.7 m
  4. P2 = 15 × 1.2069³ = 15 × 1.7581 = 26.37 kW