Useful Equations And Conversions - Extech Instruments 407123 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 0.4464
H
W
A = W x H
3
/min) = Air Velocity (ft/min) x Area (ft
3
/min) = Air Velocity (m/sec) x Area (m
ft/min
196.87
1
101.27
54.69
87.89
2 3
= ft /min (CFM)
R
2
A = pi x R
2
) x 60
knots km/hr
1.944 3.6
0.00987 0.01829
1 1.8519
0.54 1
0.8679 1.6071
7
2
)
MPH
2.24
0.01138
1.1523
0.6222
1
Model 407123 V5.2 2/2006