Filter
Top Products
AN500-EU-EN v1.5 1/13
9
Useful Equations and Conversions
Area equations
The volume of air flowing through a duct or vent can be determined by taking the area of the duct
in square units (i.e. square feet) and multiplying this value by the measured linear velocity (i.e., feet
per minute). This gives: ft/min x ft
2
= ft
3
/min (CFM)
Cubic equations
CFM (ft
3
/min) = Air Velocity (ft/min) x Area (ft
2
)
CMM (m
3
/min) = Air Velocity (m/sec) x Area (m
2
) x 60
Units Conversion Table
m/s ft/min knots km/hr MPH
1 m/s 1 196.85 1.944 3.6 2.237
1 ft/min 0.00508 1 0.00987 0.01829 0.01136
1 knot 0.5144 101.27 1 1.852 1.151
1 km/hr 0.2778 54.68 0.54 1 0.6214
1 MPH 0.447 88 0.869 1.6093 1
Copyright © 2013 FLIR Systems, Inc.
All rights reserved including the right of reproduction in whole or in part in any form
www.extech.com
A = pi x R
2
R
A = W x H
W
H