Engineering ToolBox - Resources, Tools and Basic Information for Engineering and Design of Technical Applications!

This is an AMP page - Open full page! for all features.

Air Duct Velocities

Ductwork and recommended air velocities

Sponsored Links

Flow velocity in air ducts should be kept within certain limits to avoid noise and unacceptable friction loss and energy consumption. Low velocity design is very important for the energy efficiency of the air distribution system. Doubling the duct diameter reduces the friction loss by factor 32.

Low and Medium Pressure Loss Ducts

  • Maximum friction rate 0.1 - 0.2 inches W.G./100 ft
  • Velocity 1500 - 2000 ft/min (8 - 10 m/s)
Air Flow RateMaximum Velocity
(m3/h)(CFM)(m/s)(ft/min)
< 300 < 175 2.5 490
< 1000 < 590 3 590
< 2000 < 1200 4 785
< 4000 < 2350 5 980
< 10000 < 5900 6 1180
> 10000 > 5900 7 1380

High Pressure Loss Ducts

  • Maximum friction rate less than 0.4 inches W.G./100 ft
  • Velocity 2000 - 3500 ft/min (10 - 18 m/s)

Shafts

Air Flow RateMaximum Velocity
(m3/h)(CFM)(m/s)(ft/min)
< 5000 < 2950 12 2350
< 10000 < 5900 15 2950
< 17000 < 10000 17 3350
< 25000 < 14700 20 3940
< 40000 < 23500 22 4300
< 70000 < 41000 25 4900
< 100000 < 59000 30 5800

It is common to keep main duct velocity above 20 m/s (3940 ft/min).

Corridors

Air Flow RateMaximum Velocity
(m3/h)(CFM)(m/s)(ft/min)
< 5000 < 2950 10 2000
< 10000 < 5900 12 2350
< 17000 < 10000 15 2950
< 25000 < 14700 17 3350
< 40000 < 23500 20 3940

User Areas

  • Offices, receptions, lounges and similar
Air Flow RateMaximum Velocity
(m3/h)(CFM)(m/s)(ft/min)
< 5000 < 2950 10 2000
< 10000 < 5900 12 2350
< 17000 < 10000 14 2750
< 25000 < 14700 16 3150

Typical Air Velocity Guidelines

Low Velocity Duct Systems

  • typical 400 - 2000 ft/min (2 - 10 m/s)
ApplicationsRecommended
Maximum
Velocity
(ft/min)
Cafeterias 1800
Stores, restaurant, shops, banks 1500
Offices, libraries, class rooms 1200
Apartments, hotel rooms 1000
Auditoriums, churches, cinemas, theaters 800
Residences 600

Medium Velocity Duct Systems

  • typical 2000 - 2500 ft/min (10 - 12.5 m/s)

High Velocity Duct Systems

  • typical 2500 - 3000 ft/min (12.5 - 15 m/s)

Sponsored Links

Related Topics

Related Documents

Sponsored Links

Share

Search Engineering ToolBox

  • the most efficient way to navigate the Engineering ToolBox!

SketchUp Extension - Online 3D modeling!

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

Privacy

We don't collect information from our users. Only emails and answers are saved in our archive. Cookies are only used in the browser to improve user experience.

Some of our calculators and applications let you save application data to your local computer. These applications will - due to browser restrictions - send data between your browser and our server. We don't save this data.

Google use cookies for serving our ads and handling visitor statistics. Please read Google Privacy & Terms for more information about how you can control adserving and the information collected.

AddThis use cookies for handling links to social media. Please read AddThis Privacy for more information.

Topics

Unit Converters

Temperature

oC
oF


Load Calculator!

Length

m
km
in
ft
yards
miles
naut miles


Load Calculator!

Area

m2
km2
in2
ft2
miles2
acres


Load Calculator!

Volume

m3
liters
in3
ft3
us gal


Load Calculator!

Weight

kgf
N
lbf


Load Calculator!

Velocity

m/s
km/h
ft/min
ft/s
mph
knots


Load Calculator!

Pressure

Pa (N/m2)
bar
mm H2O
kg/cm2
psi
inches H2O


Load Calculator!

Flow

m3/s
m3/h
US gpm
cfm


Load Calculator!

9 13

This website use cookies. By continuing to browse you are agreeing to our use of cookies! Learn more