Extech Instruments EN510 User Manual page 6

Air Flow (CFM, CMM) Volume Measurements
• Press and hold the M button until 'AirFl' appears.
• Enter the duct area (in square feet or meters) by short pressing M and long pressing R until
2
'm-2' (m ) or 'f-2' (ft
the area; Long press the power or H button to scroll quickly. See area equations below.
• Short press
• Remember to convert inches, centimeters, or other unit to square feet or square meters
before entering the area; otherwise, the air flow readings will not be correct.
• Place the vane in the air duct and read the air flow reading in CFM (ft
the LCD.
Area equation for rectangular or square ducts
Width (W)
Area equation for circular ducts
Cubic equations
CFM (ft 3 /min) = Air Velocity (ft/min) x Area (ft
CMM (m 3 /min) = Air Velocity (m/s) x Area (m
2 ) appears. Short press the power button to increase or H to decrease
to save.
Height (H)
Radius (r)
Area (A) = Width (W) x Height (H)
π
Area (A) =
2
x r
π
= 3.14 and r
Where
2 )
2 ) x 60
6
3 ) or CMM (m
2 = radius x radius
EN510-en-GB_V1.0 8/17
3 ) units on