Pipe Flow & Pressure Drop Planner
Screen velocity, major friction, minor fitting loss and pump head for preliminary hydronic design.
Screening range only. The upper field starts at 2.5 m/s, the same check already used by the chilled-water planner on this site. It is not a cited code limit, and it does not change head loss. Leave the minimum blank for an upper check only.
Engineering use case
For a chilled-water branch carrying 5 L/s through 50 mm pipe over 30 m, compare total head with available pump head and resize when velocity or loss exceeds the project criterion.
Method & limitations
Method: continuity, Reynolds number, Darcy–Weisbach, and KρV²/2. Laminar Re < 2300 uses f = 64/Re. Transition 2300 ≤ Re < 4000 uses a labeled log-Re blend between those limits and does not apply Blasius or Swamee–Jain inside the band. Turbulent Re ≥ 4000 uses Swamee–Jain (1976). The screening velocity range is a warning only and does not change those formulas. Calculated velocity is not a recommended design size. Default water at 7 °C: ρ = 999.9 kg/m³, μ = 1.4271×10⁻³ Pa·s, from the Anton Paar table citing IAPWS 2008 viscosity (density 0.9999 g/cm³). ε = 1.5×10⁻⁶ m, g = 9.80665 m/s². This is a pinned screening row, not an in-repo IAPWS-95 solver.
Formulas, source and scope
Formula source: site methodology / engineering assumption in this repository. No standard edition is pinned for this tool.
FAQ
What water properties are assumed?
If you do not override them, the engine uses the pinned 7 °C liquid-water row ρ = 999.9 kg/m³ and μ = 1.4271×10⁻³ Pa·s (Anton Paar table citing IAPWS 2008 viscosity; density 0.9999 g/cm³). ε = 1.5×10⁻⁶ m and g = 9.80665 m/s². Laminar Re < 2300 uses 64/Re. Transition uses a labeled log-Re blend, not Blasius. Turbulent Re ≥ 4000 uses Swamee–Jain.
How do I reproduce the branch example?
Enter 0.005 m³/s, 0.05 m, 30 m and K = 4, which is the 5 L/s, 50 mm, 30 m case described above. Continuity gives about 2.55 m/s. That velocity is not a recommended design size. The upper screening field starts at 2.5 m/s, so this example warns unless you raise the limit. Total head adds the static head you enter. The warning does not change head loss.
Compare with duct airflow pressure-loss planning → · Continue to pump duty →