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# Air Ducts - Friction Loss Diagram

## A major friction loss diagram for air ducts - in imperial units ranging 10 000 - 400 000 cfm.

Friction loss (head loss) in standard air ducts:

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

Friction loss in a 60 inches duct with air flow 100,000 cfm can be estimated to approximately 0.4 inches water per 100 feet duct as shown in the diagram above. Air velocity can be estimated to approximately 5000 feet per minute.

## Related Topics

• ### Ventilation Systems

Design of systems for ventilation and air handling - air change rates, ducts and pressure drops, charts and diagrams and more.

## Related Documents

• ### Air Ducts - Friction Loss Diagram

A major friction loss diagram for air ducts - SI units.
• ### Air Ducts - Friction Loss Diagram

A major friction loss diagram for air ducts - Imperial units ranging 10 - 100 000 cfm.
• ### Darcy-Weisbach Equation - Major Pressure and Head Loss due to Friction

The Darcy-Weisbach equation can be used to calculate the major pressure and head loss due to friction in ducts, pipes or tubes.
• ### Energy Equation - Pressure Loss vs. Head Loss

Calculate pressure loss - or head loss - in ducts, pipes or tubes.

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## Citation

• The Engineering ToolBox (2008). Air Ducts - Friction Loss Diagram. [online] Available at: https://www.engineeringtoolbox.com/ductwork-friction-loss-d_1131.html [Accessed Day Month Year].

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4.19.9

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