Combustion Air Velocity Calculator

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Keeping Duct Velocity in a Safe Range

Combustion air ductwork has to move air fast enough to avoid oversized ducts, but not so fast that pressure loss and noise become a problem. Velocity is simply flow rate divided by duct cross-sectional area.

The Formula

Velocity = Volumetric Flow Rate / Duct Cross-Sectional Area

Worked Example

A duct carrying 2 m3/s through a 0.5 m2 cross-section:

Velocity = 2 / 0.5 = 4 m/s

How to Use This Calculator

  1. Enter the Volumetric Flow Rate through the duct.
  2. Enter the Duct Cross-Sectional Area.
  3. Select Calculate to get air velocity.

Related Calculations

Find the flow rate this velocity is based on in the Combustion Air Flow Calculator, or check similar velocity math for exhaust in the Stack Gas Velocity Calculator.