Duct Air Velocity
Duct Air Velocity
Duct velocity sets noise, friction and comfort; it follows from the flow rate and the duct cross-section.
The velocity is v = Q/A. where Q is the volume flow and A the duct area.
Inputs
Q := 1.2 m^3/s=1.2 m^3/s
A := 0.16 m^2=0.16 m^2
Divide flow by duct area.
v := Q/A=7.5 m/s
Results
Typical comfort ductwork keeps velocities around 3–6 m/s — fast enough to be compact but slow enough to stay quiet. Higher velocities mean more fan energy.
Assumptions & limitations
- Duct running full.
- Mean velocity.
- Constant cross-section.