Calculate dimensionless suction specific speed Ωss to assess cavitation susceptibility of a centrifugal pump.
Turbomachinery · CavitationFormula
Variables
Cavitation Risk Thresholds (SI, dimensionless)
| Ωss range | Risk | Recommendation |
|---|---|---|
| < 0.3 | Low | Safe — standard NPSH margin adequate |
| 0.3 – 0.5 | Moderate | Increase NPSHₐ or reduce speed |
| > 0.5 | High | Redesign inlet geometry or reduce N |
US customary (N in rpm, Q in US gpm, H in ft) gives Ωss values ~13× larger — thresholds differ accordingly (safe typically S < 4).
Suction specific speed is analogous to specific speed but uses NPSHᵣ instead of head. It indicates the pump's suction performance independent of size. Lower Ωss values reflect a more cavitation-resistant design.