Extech Instruments AN100 Manual

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AN100-en-GB_V3.5 6/15

UsefulEquationsandConversions

Areaequationforrectangularorsquareducts

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Areaequationforcircularducts

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Cubicequations

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NOTE:Measurementsmadeininches

mustbeconvertedtofeetormetersbeforeusingtheaboveformulae.

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UnitofMeasureConversionTable

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 m/s ft/min knots km/h MPH

1m/s 1 196.87 1.944 3.6 2.24

1ft/min 0.00508 1 0.00987 0.01829 0.01138

1knot 0.5144 101.27 1 1.8519 1.1523

1km/h 0.2778 54.69 0.54 1 0.6222

1MPH 0.4464 87.89 0.8679 1.6071 1

Width (W)

Height (H)

Area (A) = Width (W) x Height (H)

CFM (ft

/min) = Air Velocity (ft/min) x Area (ft

)

CMM (m

/min) = Air Velocity (m/sec) x Area (m

) x 60

Radius

Area (A) =

π x r

Where

π= 3.14 and r

= radius x radius