Research — Illustrative (draft, unvalidated)
Pipe velocity regimes
Pick a flow in litres per minute and a pipe diameter. The velocity is checked against whichever cited rule applies to that size: one below 2 in, a different one above 3 in. In between there is no cited rule, and the page says so instead of showing a pass.
Pipe section, diameter regimes and velocity gauge (schematic; gap sizes are hatched, not green)
Flow
Pipe diameter
Nominal size · sets the diameter above
mm = in × 25.4. The 3 in chip uses the exact product, which the harness keeps in the gap; typing 76.2 mm lands a floating-point hair above 3 in and reads as large pipe.
Pipe velocity
Velocity
Cited limit
Margin to limit
How the check read it
Client-side port:the logic and table in this page are a TypeScript port of the harness function, checked against values exported from the Python tests. Not a live API call. Domain maturity, quoted from the research page: “Draft; no mechanical or thermal engineer has reviewed it yet. An audit of the input data caught real discrepancies, and the functions use whatever value a caller passes without correcting it. Pipe-velocity limits are cited to ASHRAE through secondary sources only.” The small-pipe limit (4 fps, 1.2192 m/s, up to 2 in) and the absolute ceiling (15 fps, 4.572 m/s) come from the ASHRAE Handbook through secondary sources; the large-pipe limit (2.1 m/s, above 3 in) is attributed to ASHRAE TC 9.9's Liquid Cooling Guidelines (2014) through a secondary trade-press source, with the primary text not accessed. Flow and diameter are values you enter.Real function this maps to:
evaluate_pipe_velocity_for_flow_rate.Not modeled: pressure drop (no Darcy-Weisbach), inside diameter or schedule wall thickness (nominal diameter is used, so real velocity is somewhat higher), fluid properties, any rule for the 2 to 3 inch range, and automatic size selection. A gap-size result is never a pass and the harness never picks a pipe size. Whether the diameter is DN, NPS or inside diameter is the caller's job to confirm.See also:Pipe velocity, auto sweep · Cooling capacity margin