The effects on centrifugal pumps with limited change of speed (RPM) or impeller diameter.

1. Capacity (Q) varies directly as the speed (N) or impeller diameter (D).
2. Head (H) varies as the square of the speed or impeller diameter.
3. BHP varies as the cube of the speed or impeller diameter.

• Law 1 = Q^1/Q^2 = N^1/N^2 or D^1/D^2
• Law 2 = H^1/H^2 = (N^1/N^2)^2 or (D^1/D^2)^2
• Law 3 = P^1/P^2 = (N^1/N^2)^3 or (D^1/D^2)^3