Flow Velocity Air Ducts

Reference data and engineering information about flow velocity air ducts for hvac systems applications.

flowvelocityairductsCalculator

Overview

Engineering reference data for Flow Velocity Air Ducts in HVAC systems.

Key Formulas

Sensible Heat

$Q = \dot{m} c_p \Delta T$

Heat causing temperature change.

Latent Heat

$Q = \dot{m} h_{fg} \Delta\omega$

Heat causing moisture change.

COP (Cooling)

$COP = Q_c / W$

Coefficient of performance.

Variables

Symbol	Description	Unit
$Q$	Heat transfer	W
$\dot{m}$	Mass flow rate	kg/s
$c_p$	Specific heat of air	J/(kg·K)
$\Delta T$	Temperature difference	K

Recommended Air Velocity Guidelines

Air velocities in ducts and pipes should not exceed certain limits to avoid high pressure loss and unacceptable noise generation. The following table provides guidelines for some typical applications.

7 rows

Recommended Air Velocities for Common Duct Applications
Air Duct Application	Velocity(m/s)	Velocity(ft/min)
Combustion air duct	12 - 20	2400 - 4000
Air inlet to boiler room	1 - 3	200 - 600
Warm air for house heating	0.8 - 1.0	150 - 200
Vacuum cleaning pipe	8 - 15	1500 - 3000
Compressed air pipe	20 - 30	4000 - 6000
Ventilation ducts in hospitals	5 - 8	1000 - 1500
Ventilation ducts in office buildings	7 - 11	1200 - 2000

Source: engineeringtoolbox.com

These velocity ranges are practical guidelines. Selecting a velocity within these limits helps balance energy efficiency, noise control, and system cost. High velocities increase pressure drop and fan energy consumption, while excessively low velocities may require oversized, costly ductwork.

References

Original Source

Source: engineeringtoolbox.com