Hydraulic Hose Pressure Drop Calculator

Inputs

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Oil flow through the hose.
L/min
Actual hose bore / inside diameter, not nominal dash size.
mm
Total hose length.
m
Oil kinematic viscosity at operating temperature. ISO VG 46 oil is about 46 cSt at 40°C.
cSt
Fluid density relative to water. Mineral hydraulic oil is often around 0.85-0.90.
Equivalent internal roughness. Smooth hose is low; old or rough pipe is higher.
mm
Sum of minor-loss K values for elbows, adapters, quick couplers and fittings.

Results

Default result
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Pressure drop (Δp)
0.4652 bar
Pass

f = 0.0659, laminar flow

Also computed

Oil velocity (v) Pass 2.351 m/s

typical pressure-line range

Reynolds number (Re) 971.2

laminar

Power loss (P_loss) 0.03101 kW

Method notes 3 notes
  • Darcy-Weisbach: Δp = (f·L/D + ΣK) · ρ·v²/2. Laminar f = 64/Re; turbulent f uses the Swamee-Jain approximation.
  • Use oil viscosity at operating temperature. Cold oil can be many times more viscous and will drop far more pressure.
  • The fitting coefficient ΣK is a screening input; vendor pressure-drop curves are better for quick couplers, valves and complex fittings.

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