Air Ducts Friction Loss Diagram

Major loss diagram air ducts - Imperial units ranging 10 - 100 000 cfm

Friction loss (head loss) in standard air ducts are indicated in the diagram below:

air ductwork friction loss diagram

The diagram is based on standard air 0.075 lb/ft3 in clean round galvanized metal ducts.

  • 1 inch water = 248.8 N/m2 (Pa)= 0.0361 lb/in2 (psi) = 25.4 kg/m2 = 0.0739 in mercury
  • 1 ft3/min (cfm) = 1.7 m3/h = 0.47 l/s
  • 1 ft/min = 5.08x10-3 m/s
  • 1 inch = 25.4 mm = 2.54 cm = 0.0254 m = 0.08333 ft

Example - Friction Loss in Air Duct

The friction loss in a 20 inches duct with air flow 4000 cfm can be estimated to approximately 0.23 inches water per 100 feet duct as shown in the diagram below. The air velocity can be estimated to approximately 1850 feet per minute.

ductworks friction loss diagram example 

Related Mobile Apps from The Engineering ToolBox Engineering Toolbox Apps

- free apps for offline use on mobile devices

Related Topics

  • Ventilation - Systems for ventilation and air handling - air change rates, ducts and pressure drops, charts and diagrams and more

Related Documents

Search the Engineering ToolBox

- "the most efficient way to navigate the Engineering ToolBox!"

Engineering ToolBox - SketchUp Edition - Online 3D modeling!

3D Engineering ToolBox - draw and model technical applications

Engineering ToolBox - SketchUp Edition - add standard and customized parametric components - like flange beams, lumbers, piping and more - to your SketchUp model - enabled for use with the amazing, fun and free SketchUp Make and SketchUp Pro. Add from the Sketchup Extension Warehouse!

Translate the Engineering ToolBox!
About the Engineering ToolBox!

close