Duct pressure drop using Darcy–Weisbach friction factor.
Rectangular ducts use hydraulic diameter. Fittings via K-factor (ΣK).
Airflow & Duct
m³/s
m
Duct Geometry
mm
mm
mm
Material & Air
mm
°C
kPa
Fittings
0 fittings
ΣK = 0.00
Enter values to calculate duct pressure drop
Darcy friction factor (Swamee–Jain). Air: ideal gas density + Sutherland viscosity.
Typical UK comfort: main ducts 5–8 m/s, branches 3–6 m/s. Verify to project specification.
Typical UK comfort: main ducts 5–8 m/s, branches 3–6 m/s. Verify to project specification.