Useful Equations - Extech Instruments HD350 User Manual

Useful Equations

Calculating the Area for rectangular or square ducts
Rectangle: Area (A) = Height (b) x Width (a)
Circle: Area (A) =
Cubic equations
3
CFM (ft /min) = Air Velocity (ft/min) x Area (ft
3
CMM (m /min) = Air Velocity (m/sec) x Area (m
NOTE: Measurements made in inches must be converted to feet or meters.
netzerotools.com
 
2 
= 3.14 and r
x r (Where
a
netzerotools.com
2
= radius x radius)
r
b
2
)
2
) x 60
15
HD350-EU-EN V3.1 07/13