Pipe Flow Reynolds Number and Regime

Re = V D / nu sorts pipe flow into laminar (Re < 2,300), transitional, and turbulent (Re > 4,000). 60 F water at 6 ft/s in a 2 in line runs Re 82,600 - firmly turbulent, as nearly all trade piping is, which is why the Hazen-Williams and Colebrook forms apply; slow it to a crawl and Re 275 laminar, where f = 64/Re and loss is linear in velocity. Enter the kinematic viscosity for the fluid and temperature. An engineering aid; the fluid property data govern.

Re = V (D/12) / nu; regime = Re < 2,300 laminar, <= 4,000 transitional, else turbulent.

The Reynolds number Re = V D / nu (= rho V D / mu) and the standard pipe-flow transition bands, with a 60 degF water kinematic viscosity of about 1.21e-5 ft^2/s, a standard fluid-mechanics result, by name.

The Reynolds-number definition and the pipe-flow transition bands are public results in any fluid-mechanics reference.

Estimate. AHJ and licensed professional govern.

Field names used by the API: v_fps, d_in, nu, re

• Reynolds number Re = V D / nu, velocity times diameter over kinematic viscosityfluid mechanics
• Regime bands laminar below ~2,300, transitional ~2,300 to 4,000, turbulent above ~4,000pipe-flow convention
• Viscosity entered per fluid and temperature; ~1.21e-5 ft^2/s for 60 degF waterfluid property tables