Calculate flow velocity, pressure drop, and Reynolds number for pipe sizing
Uses Darcy-Weisbach and Hazen-Williams equations for water and fluid system design.
Darcy-Weisbach is more accurate and works for all fluids and flow conditions. Hazen-Williams is an empirical formula simpler to use but valid only for water at normal temperatures and turbulent flow. Use Darcy-Weisbach for engineering accuracy; Hazen-Williams for quick water system estimates.
Reynolds Number predicts flow patterns. Re < 2100 is Laminar (smooth, parallel flow). Re > 4000 is Turbulent (chaotic mixing). The transition zone is 2100-4000. This determines which friction factor formula applies.
Use the pipe sizing mode: enter your required flow rate (GPM or L/s), pipe material (C-factor or roughness), and maximum acceptable pressure drop per unit length. The calculator solves for the minimum pipe diameter that meets the flow requirement without excessive friction loss.
Friction factor (f) quantifies energy loss due to pipe wall friction. For laminar flow, f = 64/Re. For turbulent flow, the Moody chart or Colebrook-White equation is used. This calculator computes friction factor automatically and uses it in the Darcy-Weisbach pressure drop equation.
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Pipe Flow / Pressure Drop Calculator
Calculate pressure drop, flow rate, and fluid velocity in pipes. Supports Darcy-Weisbach and Hazen-Williams methods with minor losses.