Pump Speed for Target Duty Calculator
VFD speed needed to hit a reduced target head or flow, via affinity laws.
Pure affinity assumes the system curve passes through the origin (all friction). With static head, the real speed needed is higher — converge with the system-curve tool.
Formula
Pump Speed for Target Duty Calculator is a free pump speed for 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 Speed for Target Duty Calculator
VFD speed needed to hit a reduced target head or flow, via affinity laws. The calculation implements N₂ = N₁·(Q₂/Q₁); P₂/P₁ = (N₂/N₁)³ (ANSI/HI 14.3). Pure affinity assumes the system curve passes through the origin (all friction). With static head, the real speed needed is higher — converge with the system-curve tool.
How to use Pump Speed for Target Duty Calculator
- 1Enter Current speed in rpm.
- 2Enter Current flow in m³/h.
- 3Enter Target flow in m³/h.
- 4Read Required speed, VFD frequency (50 Hz base), Power vs full speed instantly — no submit button needed.
- 5Need US units? Flip the SI/Imperial toggle and every field converts.
Why use Pump Speed for Target Duty Calculator?
- ✓Implements the standard formula — N₂ = N₁·(Q₂/Q₁); P₂/P₁ = (N₂/N₁)³
- ✓Reference cited on-page: ANSI/HI 14.3
- ✓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 Speed for Target Duty Calculator use?+
It computes N₂ = N₁·(Q₂/Q₁); P₂/P₁ = (N₂/N₁)³, per ANSI/HI 14.3. 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?+
Pure affinity assumes the system curve passes through the origin (all friction). With static head, the real speed needed is higher — converge with the system-curve tool.
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 Speed for Target Duty 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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