Parallel Pipes Flow Split Calculator
How flow divides between two parallel pipes of different size and length.
Equal head loss across both branches governs the split. A pipe one size larger steals roughly 2.5× the flow of its smaller twin of equal length.
Formula
Parallel Pipes Flow Split Calculator is a free parallel pipes 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 Parallel Pipes Flow Split Calculator
How flow divides between two parallel pipes of different size and length. The calculation implements h_f1 = h_f2 → Q₁/Q₂ = (R₂/R₁)^(1/1.852), R = L/D^4.87 (Hazen-Williams parallel-pipe analysis — AWWA M11). Equal head loss across both branches governs the split. A pipe one size larger steals roughly 2.5× the flow of its smaller twin of equal length.
How to use Parallel Pipes Flow Split Calculator
- 1Enter Total flow in L/s.
- 2Enter Pipe 1 diameter in mm.
- 3Enter Pipe 1 length in m.
- 4Enter Pipe 2 diameter in mm.
- 5Read Flow in pipe 1, Flow in pipe 2 instantly — no submit button needed.
- 6Need US units? Flip the SI/Imperial toggle and every field converts.
Why use Parallel Pipes Flow Split Calculator?
- ✓Implements the standard formula — h_f1 = h_f2 → Q₁/Q₂ = (R₂/R₁)^(1/1.852), R = L/D^4.87
- ✓Reference cited on-page: Hazen-Williams parallel-pipe analysis — AWWA M11
- ✓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 Parallel Pipes Flow Split Calculator use?+
It computes h_f1 = h_f2 → Q₁/Q₂ = (R₂/R₁)^(1/1.852), R = L/D^4.87, per Hazen-Williams parallel-pipe analysis — AWWA M11. The formula is displayed under the result.
What should I keep in mind when using this calculator?+
Equal head loss across both branches governs the split. A pipe one size larger steals roughly 2.5× the flow of its smaller twin of equal length.
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 Parallel Pipes Flow Split 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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