NPSHr Speed Correction Calculator
Estimate NPSH required at a new speed — NPSHr scales roughly with N².
Speeding a 50 Hz pump to 60 Hz raises NPSHr ~44% — the most common cavitation surprise in exported equipment.
Formula
Note: Exponent varies 1.5–2.5 between designs; confirm with the manufacturer for critical services.
NPSHr Speed Correction Calculator is a free npshr speed for pump engineers, plumbers and plant designers — instant, accurate and 100% client-side, with the governing formula and reference shown next to the result so the number can be defended, not just quoted.
About NPSHr Speed Correction Calculator
Estimate NPSH required at a new speed — NPSHr scales roughly with N². The calculation implements NPSHr₂ ≈ NPSHr₁·(N₂/N₁)² (Karassik, Pump Handbook). Speeding a 50 Hz pump to 60 Hz raises NPSHr ~44% — the most common cavitation surprise in exported equipment.
How to use NPSHr Speed Correction Calculator
- 1Enter NPSHr at N₁ (curve) in m.
- 2Enter Curve speed N₁ in rpm.
- 3Enter Operating speed N₂ in rpm.
- 4Read Estimated NPSHr at N₂ instantly — no submit button needed.
- 5Need US units? Flip the SI/Imperial toggle and every field converts.
Why use NPSHr Speed Correction Calculator?
- ✓Implements the standard formula — NPSHr₂ ≈ NPSHr₁·(N₂/N₁)²
- ✓Reference cited on-page: Karassik, Pump Handbook
- ✓One-click SI ⇄ Imperial toggle — values convert in place, physics stays in SI
- ✓Live worked example: the substitution recomputes from your numbers
- ✓Runs entirely in your browser — nothing uploaded, free forever
Frequently asked questions
What formula does the NPSHr Speed Correction Calculator use?+
It computes NPSHr₂ ≈ NPSHr₁·(N₂/N₁)², per Karassik, Pump Handbook. The formula is displayed under the result along with a worked example substituted with your own inputs.
What should I keep in mind when using this calculator?+
Speeding a 50 Hz pump to 60 Hz raises NPSHr ~44% — the most common cavitation surprise in exported equipment. Note: Exponent varies 1.5–2.5 between designs; confirm with the manufacturer for critical services.
Can I use this for pump selection?+
Use it to establish the duty (flow, head, NPSH, power) and then pick a pump whose curve passes through that point near best efficiency. The tool gives you the engineering numbers a supplier will ask for.
Is the NPSHr Speed Correction Calculator free to use?+
Yes — completely free, no sign-up, no limits. It runs client-side in your browser, so inputs stay private and results are instant even on slow connections.
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