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.

Duct Velocity

Calculate velocities in circular and rectangular ducts - imperial and SI-units - online calculator.

Sponsored Links

Air Duct Velocity - Imperial Units

Air velocity in a ventilation duct can be calculated in imperial units as

vi = qi / Ai

    = qi / [π (df / 2)2)]  

    = qi / [π ((di  / 12) / 2)2)]

    = (576 / π) (qi / di2)

    = 144 qi / (ai bi)                                   (1)

where

vi = air velocity (ft/min)

qi = air flow (ft3/min)

Ai = area of duct (ft2)

df = diameter of duct (ft)

di = diameter of duct (in)

ai = width of duct (in)

bi = width of duct (in)

Example - Air Flow Velocity in a Duct

The velocity in a 12 inch duct with air flow 1000 cfm can be calculated as

vi = (576 / π)  (1000 cfm) / (12 in)2)

   = 1273 (ft/min)

Air Flow Velocity Calculator - Imperial Units

Air velocity can be calculated with the calculator below. Add air volume - q - and diameter - d - (or length a and b).

Air volume - qi - (cfm)

Diameter - di - (inches)

or alternatively

Length side - ai - (inches)

Length side - bi - (inches)


Load Calculator!

Related Mobile Apps from The Engineering ToolBox

- free apps for offline use on mobile devices

Air Duct Velocity - SI Units

Air velocity in a duct can be calculated in SI units

vm = qm / Am

     = qm / (π (dm / 2)2)

     = 4 qm / (π dm2)

     = qm / (am bm)                                  (2)

where

vm = air velocity (m/s)

qm = air flow (m3/s)

Am = area of duct (m2)

dm = diameter of duct (m)

am = width of duct (m)

bm = width of duct (m)

Example - Air Flow Velocity in a Duct

The velocity in a rectangular 0.5 m x 0.5 m duct with air flow 1 m3/s can be calculated as

vm = (1 m3/s) / ((0.5 m) (0.5 m))

   = 4 (m/s)

Air Flow Velocity Calculator - SI Units

Air velocity can be calculated with the calculator below. Add air volume - q - and diameter - d - (or length a and b).

Air volume - qm - (m3/s)

Diameter - dm - (m)

or alternatively

Length side - am - (m)

Length side - bm - (m)


Load Calculator!

Air Ducts - Velocity Diagram

The chart below can be used to estimate velocities in air ducts.

The default values are for air flow 400 cfm (680 m3/h), duct size 8 in (200 mm) and velocity 1150 fpm (5.8 m/s).

Download and print Air Ducts - Velocity Diagram!

Air Ducts Friction Loss

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!

3 30

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