Cavitation Number Calculator
Cavitation index σ for valves, propellers and venturis — margin above vapour pressure.
Hot water cavitates far more easily: at 60 °C the vapour pressure is 8× the 20 °C value, slashing σ for the same flow.
Formula
Disclaimer: This tool is for general informational and estimation purposes only and is not professional financial, tax, accounting or legal advice. All figures are estimates — verify with a qualified professional before making decisions. Read the full disclaimer.
Cavitation Number Calculator is a free cavitation number for process, mechanical and water engineers — 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 Cavitation Number Calculator
Cavitation index σ for valves, propellers and venturis — margin above vapour pressure. The calculation implements σ = (P − P_v) / (½·ρ·V²) (Brennen, Cavitation and Bubble Dynamics; ISA RP75.23 — control valve cavitation). Hot water cavitates far more easily: at 60 °C the vapour pressure is 8× the 20 °C value, slashing σ for the same flow.
How to use Cavitation Number Calculator
- 1Enter Local static pressure (abs) in kPa(a).
- 2Enter Vapour pressure (abs) in kPa(a) (Water 20 °C = 2.34; 60 °C = 19.9).
- 3Enter Density in kg/m³.
- 4Enter Characteristic velocity in m/s.
- 5Read Cavitation number σ instantly — no submit button needed.
- 6Need US units? Flip the SI/Imperial toggle and every field converts.
Why use Cavitation Number Calculator?
- ✓Implements the standard formula — σ = (P − P_v) / (½·ρ·V²)
- ✓Reference cited on-page: Brennen, Cavitation and Bubble Dynamics; ISA RP75.23 — control valve cavitation
- ✓One-click SI ⇄ Imperial toggle — values convert in place, physics stays in SI
- ✓Live worked example: the substitution recomputes from your numbers
- ✓Built-in engineering verdict flags out-of-range results instantly
- ✓Runs entirely in your browser — nothing uploaded, free forever
Frequently asked questions
What formula does the Cavitation Number Calculator use?+
It computes σ = (P − P_v) / (½·ρ·V²), per Brennen, Cavitation and Bubble Dynamics; ISA RP75.23 — control valve cavitation. 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?+
Hot water cavitates far more easily: at 60 °C the vapour pressure is 8× the 20 °C value, slashing σ for the same flow.
Does this work for any fluid?+
Yes — density and viscosity are inputs (with common fluids suggested in the field hints), so the same physics applies to water, oils, gases and process fluids. Compute always runs in SI internally, so unit mix-ups can't corrupt the result.
Is the Cavitation Number 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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