User manual

HD350-en-GB_V3.2 7/15
15
Useful Equations
Calculating the Area for rectangular or square ducts
Rectangle: Area (A) = Height (b) x Width (a)
Circle: Area (A) =
 x r
2
(Where = 3.14 and r
2
= radius x radius)
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
NOTE: Measurements made in inches must be converted to feet or meters.
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a
b
r