Model 451126 V2.0 6/08
9
Useful Equations and Conversions
Area equations
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
196.87
1.944
3.6
2.24
1 ft/min
0.00508
1
0.00987
0.01829
0.01138
1 knot
0.5144
101.27
1
1.8519
1.1523
1 km/hr
0.2778
54.69
0.54
1
0.6222
1 mph
0.4464
87.89
0.8679
1.6071
1
R
W
H
Area = W x H
Rectangular Duct
Circular Duct
π
R
2
A=
(A= 3.14 x R x R)