Axial fans

Dimensioning / change in speedCurveInfluence of speed n[%]160A change in speed influences:– Air flow VV ~ n100 120 1401.1n1.2n1.4n1.3n– Static pressure increase p fa∆p fa ~ n 2800.9nn– Requirement of energy P 1600.8nP 1 ~ n 3 140400.7n0.6n020020 40 60 80 100 120[%]CurveInfluence of the speed n on the sound level Lw[dB]When the speed changes, the approximate sound level can bedetermined using the diagram to the right and the following formula:Lw 2 - Lw 1 = 50 dB . log (n 2 :n 1 )Lw 1 = Sound level after speed changeLw 2 = Sound level before speed changen 1n 2= Changed speed= Starting speedmodification in sound pressure level-20 -10 0 10 200,511,52 2,5 3factor of speed change408