Air Ducts  Friction Loss Diagram
A major friction loss diagram for air ducts  SI units.
Friction loss in standard air ducts:
Download and print Air Duct Pressure Loss vs. Air Flow and Duct Dimension Chart
 1 m/s = 196.85 ft/min
 1 m^{3}/s = 3600 m3/h = 1000 dm^{3}(liter)/s = 35.32 ft^{3}/s = 2118.9 ft^{3}/min = 13200 Imp.gal (UK)/min = 15852 gal (US)/min
 1 mm H_{2}O = 9.81 Pa = 9.807x10^{6} N/mm^{2} = 0.0987 10^{3} bar = 1 kp/m^{2} = 0.09678 10^{3} atm = 1.422 10^{3} psi (lb_{f}/in^{2})
Example  Air Duct and Friction Loss
As indicated in the diagram above, the friction loss in a 500 mm main duct with air flow 1 m^{3}/s  in a comfort system with air velocity limited to 5 m/s  can be estimated to 0.55 Pa/m (0.055 mm H_{2}O/m).
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