Velocity from Flow Rate Calculator
Back out water velocity in a pipe from flow rate and bore, checked against recommended design limits.
Water-distribution mains are commonly designed for 0.9โ2.4 m/s (3โ8 ft/s); pump suctions are kept slower to protect NPSH.
Formula
Velocity from Flow Rate Calculator is a free velocity from flow for process, mechanical and water engineers โ 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 Velocity from Flow Rate Calculator
Back out water velocity in a pipe from flow rate and bore, checked against recommended design limits. The calculation implements V = Q / A = 4ยทQ / (ฯยทDยฒ) (ASHRAE Handbook โ Fundamentals, ch. 22 (pipe sizing)). Water-distribution mains are commonly designed for 0.9โ2.4 m/s (3โ8 ft/s); pump suctions are kept slower to protect NPSH.
How to use Velocity from Flow Rate Calculator
- 1Enter Flow rate in L/s.
- 2Enter Pipe inner diameter in mm.
- 3Read Velocity, Velocity head Vยฒ/2g instantly โ no submit button needed.
- 4Need US units? Flip the SI/Imperial toggle and every field converts.
Why use Velocity from Flow Rate Calculator?
- โImplements the standard formula โ V = Q / A = 4ยทQ / (ฯยทDยฒ)
- โReference cited on-page: ASHRAE Handbook โ Fundamentals, ch. 22 (pipe sizing)
- โOne-click SI โ Imperial toggle โ values convert in place, physics stays in SI
- โLive worked example: the substitution recomputes from your numbers
- โBuilt-in engineering verdict flags out-of-range results instantly
- โRuns entirely in your browser โ nothing uploaded, free forever
Frequently asked questions
What formula does the Velocity from Flow Rate Calculator use?+
It computes V = Q / A = 4ยทQ / (ฯยทDยฒ), per ASHRAE Handbook โ Fundamentals, ch. 22 (pipe sizing). 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?+
Water-distribution mains are commonly designed for 0.9โ2.4 m/s (3โ8 ft/s); pump suctions are kept slower to protect NPSH.
Does this work for any fluid?+
Yes โ 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 Velocity from Flow Rate Calculator free to use?+
Yes โ 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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