Useful Equations And Conversions - Extech Instruments AN500 User Manual

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
Cubic equations
CFM (ft
CMM (m
Units Conversion Table
m/s
1 m/s 1
1 ft/min 0.00508
1 knot 0.5144
1 km/hr 0.2778
1 MPH 0.447
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2 3
= ft /min (CFM)
3
/min) = Air Velocity (ft/min) x Area (ft
3
/min) = Air Velocity (m/sec) x Area (m
ft/min knot
196.85 1.944
1 0.00987
101.27 1
54.68 0.54
88 0.869
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8
2
)
2
) x 60
km/hr MPH
3.6 2.237
0.01829 0.01136
1.852 1.151
1 0.6214
1.6093 1
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