Parshall Flume Flow Calculator
Open-channel discharge through a Parshall flume from throat width and head.
Flumes self-clean and lose only ~25% of the head a weir demands — the sewage-works standard. Free-flow holds while downstream submergence stays under ~70%.
Formula
Parshall Flume Flow Calculator is a free parshall flume 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 Parshall Flume Flow Calculator
Open-channel discharge through a Parshall flume from throat width and head. The calculation implements Q = 4·W·H^(1.522·W^0.026) (cfs, ft — classic Parshall) (Parshall (1926); ISO 9826). Flumes self-clean and lose only ~25% of the head a weir demands — the sewage-works standard. Free-flow holds while downstream submergence stays under ~70%.
How to use Parshall Flume Flow Calculator
- 1Enter Throat width in m (Standard: 3 inch to 8 ft; 1 ft (0.305 m) common).
- 2Enter Upstream head H_a in m.
- 3Read Discharge, Discharge instantly — no submit button needed.
- 4Need US units? Flip the SI/Imperial toggle and every field converts.
Why use Parshall Flume Flow Calculator?
- ✓Implements the standard formula — Q = 4·W·H^(1.522·W^0.026) (cfs, ft — classic Parshall)
- ✓Reference cited on-page: Parshall (1926); ISO 9826
- ✓One-click SI ⇄ Imperial toggle — values convert in place, physics stays in SI
- ✓Runs entirely in your browser — nothing uploaded, free forever
Frequently asked questions
What formula does the Parshall Flume Flow Calculator use?+
It computes Q = 4·W·H^(1.522·W^0.026) (cfs, ft — classic Parshall), per Parshall (1926); ISO 9826. The formula is displayed under the result.
What should I keep in mind when using this calculator?+
Flumes self-clean and lose only ~25% of the head a weir demands — the sewage-works standard. Free-flow holds while downstream submergence stays under ~70%.
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 Parshall Flume 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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