Engineering & mechanics
Pump affinity scaling
Scale flow, head and power with rotational speed under ideal similarity assumptions.
A clear answer. Here’s how.
For the same impeller and fluid under similar operating conditions, Q scales with speed, head with speed squared and power with speed cubed. Outputs retain each supplied quantity’s unit. Assumes unchanged efficiency and dynamically similar operation; it does not determine the new system operating point, cavitation margin or actual motor requirement.
See a worked example
Worked example
A fixed demonstration, separate from the values you enter above.
- Original rotational speed
- 1500
- New rotational speed
- 1800
- Original flow (one consistent unit)
- 100
- Original head (one consistent unit)
- 20
- Original power (one consistent unit)
- 5
Example result
- Speed ratio
- 1.2
- Scaled flow (same volume/time unit)
- 120
- Scaled head (same length unit)
- 28.8
- Scaled power (same power unit)
- 8.64