Pump Minimum Flow Calculator
Thermal minimum flow from allowed temperature rise — protects pumps at low demand.
Near shutoff nearly all shaft power becomes heat in a trickle of liquid. Mechanical (vibration) minimum flow is often higher — take the larger of the two.
Formula
Pump Minimum Flow Calculator is a free pump minimum flow 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 Pump Minimum Flow Calculator
Thermal minimum flow from allowed temperature rise — protects pumps at low demand. The calculation implements Q_min = P·(1−η) / (ρ·c_p·ΔT_allow) (ANSI/HI 9.6.3 — allowable operating region). Near shutoff nearly all shaft power becomes heat in a trickle of liquid. Mechanical (vibration) minimum flow is often higher — take the larger of the two.
How to use Pump Minimum Flow Calculator
- 1Enter Shaft power near shutoff in kW.
- 2Enter Efficiency near min flow in %.
- 3Enter Allowable temperature rise in °C (8–10 °C typical; less for hot or volatile fluids).
- 4Read Thermal minimum flow instantly — no submit button needed.
- 5Need US units? Flip the SI/Imperial toggle and every field converts.
Why use Pump Minimum Flow Calculator?
- ✓Implements the standard formula — Q_min = P·(1−η) / (ρ·c_p·ΔT_allow)
- ✓Reference cited on-page: ANSI/HI 9.6.3 — allowable operating region
- ✓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 Pump Minimum Flow Calculator use?+
It computes Q_min = P·(1−η) / (ρ·c_p·ΔT_allow), per ANSI/HI 9.6.3 — allowable operating region. 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?+
Near shutoff nearly all shaft power becomes heat in a trickle of liquid. Mechanical (vibration) minimum flow is often higher — take the larger of the two.
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 Pump Minimum Flow 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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