GIFSQ Tools · Module 17 — Food Processing, Thermal Engineering & Utilities · Tool 337 of 500
Work out the pressure drop along a straight pipe with the Darcy-Weisbach equation, from flow rate, pipe diameter and length, density and viscosity.
Try sample values — fills the form with the worked example below.
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Velocity (m/s)
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Reynolds number
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Pressure drop (kPa)
Equation: Δp = f × (L / D) × (ρ × v² / 2); velocity v = Q / A; Re = ρ × v × D / μ; f = 64 / Re (laminar) or 0.316 × Re^( −0.25) (turbulent, Blasius, smooth pipe).
Method: Darcy-Weisbach equation with the Blasius friction factor for smooth pipes, standard fluid mechanics practice (Cengel and Cimbala; Incropera and DeWitt).
Assumptions: straight, smooth, circular pipe; fully developed flow; Newtonian fluid; no fittings or valves — add minor losses separately.
Limitations: rough pipes need the Colebrook or Haaland friction factor; non-Newtonian foods (purees, pastes) do not follow this friction model.
Rounding: velocity to 3 decimal places, Reynolds number to 0, pressure drop to 2; intermediates unrounded.
This is a calculation aid, not a laboratory report — confirm against your accredited method before citing a value.
Method: Darcy-Weisbach equation with the Blasius friction factor for smooth pipes, standard fluid mechanics practice (Cengel and Cimbala; Incropera and DeWitt).
Assumptions: straight, smooth, circular pipe; fully developed flow; Newtonian fluid; no fittings or valves — add minor losses separately.
Limitations: rough pipes need the Colebrook or Haaland friction factor; non-Newtonian foods (purees, pastes) do not follow this friction model.
Rounding: velocity to 3 decimal places, Reynolds number to 0, pressure drop to 2; intermediates unrounded.
This is a calculation aid, not a laboratory report — confirm against your accredited method before citing a value.
Worked example: 10 m³/h of water through 100 m of 50 mm pipe: velocity = 1.415 m/s, Re = 70736, pressure drop = 38.78 kPa.
Enter values above to see results.
Keep food-line velocities near 1–2 m/s: slower risks settling, faster wastes pump power and can damage shear-sensitive products. Tool 337 of 500 — GIFSQ
