Useful Equations And Conversions - Extech Instruments AN100 User Manual

Useful Equations and Conversions

Area equation for rectangular or square ducts
Area equation for circular ducts
Cubic equations
Unit of Measure Conversion Table
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Height (H)
Area (A) = Width (W) x Height (H)
Width (W)
Area (A) =
Radius
Where
CFM (ft 3 /min) = Air Velocity (ft/min) x Area (ft
CMM (m 3 /min) = Air Velocity (m/sec) x Area (m
NOTE: Measurements made in inches
must be converted to feet or meters before using the above formulae.
m/s ft/min
1 m/s 1 196.87
1 ft/min 0.00508 1
1 knot 0.5144 101.27
1 km/h 0.2778 54.69
1 MPH 0.4464 87.89
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π
x r 2
π
= 3.14 and r 2 = radius x radius
2 )
2 ) x 60
knots km/h
1.944 3.6
0.00987 0.01829
1 1.8519
0.54 1
0.8679 1.6071
10
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MPH
2.24
0.01138
1.1523
0.6222
1
AN100-en-GB_V3.6 6/18
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