Standards, correlations & further reading
- Churchill (1977) unified friction factor — see existing correlation notes.
- Piping preliminary design scenario at /tools/scenarios/piping-prelim — step 3 after GB/T 17395 sizing and wall thickness check.
- Steam thermodynamics screening: /tools/steam-calculator (IAPWS-IF97) for density inputs when needed.
Model assumptions (read before quoting results)
- Single-phase, incompressible fluid with uniform density and viscosity along the line.
- Constant pipe inner diameter D, absolute roughness ε, and mean axial velocity v over length L (developed flow; entry lengths not modeled explicitly).
- Straight-pipe loss uses Darcy–Weisbach with Darcy friction factor f from the Churchill (1977) unified correlation across laminar, transitional, and turbulent Reynolds numbers.
Shareable URL (query encodes SI inputs)
Use “Copy shareable link” below the grids. Query keys are lowercase SI tokens: rho (kg/m³), mu (Pa·s), D (m), L (m), eps (m absolute roughness), v (m/s), z (m elevation change), K (total minor-loss coefficient). Opening the link restores inputs; press Calculate again to refresh outputs after hydration. When K is present in the URL, minor-loss rows collapse to a single custom K row so the decoded total is not overwritten by default fitting rows.
Frequently asked questions
- When is Darcy–Weisbach preferred over Hazen–Williams?
- For general liquids and gases where you can supply ρ, μ, ε, and you care about Reynolds-dependent friction, Darcy–Weisbach is the more fundamental route. Hazen–Williams is an empirical water-pipe shortcut with a narrow validity window; it is still common in municipal hydraulics but should not be mixed blindly with steam, hydrocarbons, or non-water fluids.
Extended copy on this page (headings, references, assumptions, FAQs) may be drafted or localized with AI assistance; engineering judgment and governing codes still apply. Numerical models run locally in your browser as implemented. For contract-critical work, cite primary standards and qualified review.