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Fan installation guide Pressure recovery Look for opportunities for pressure recovery at centrifugal exhaust fan outlets Don't To determine the system resistance the discharge losses have to be added before selecting the fan Discharge losses are highest i

Pressure recovery Look for opportunities for pressure recovery at centrifugal exhaust fan outlets Don't To determine the system resistance the discharge losses have to be added before selecting the fan Discharge losses are highest in this arrangement and are equivalent to one velocity head Do With a correctly designed discharge di ?user the pressure recovery in the di ?user will reduce the system total pressure Included angle of di ?user to be ? or less Discharge losses reduced by up to in this arrangement CLook for opportunities for static pressure recovery at axial exhaust fan outlets Don't To determine the system resistance the discharge losses have to be added before selecting the fan Discharge losses are highest in this arrangement and are equivalent to one velocity head Do With a correctly designed discharge di ?user the pressure recovery in the di ?user will reduce the system total pressure Included angle of di ?user to be ? or less Discharge losses reduced substantially in this arrangement CSpinning of air at inlet connection Ensure spinning of air at fan inlet does not take place Don't A poorly designed inlet box can generate spinning of the air which can reduce performance by around Also avoid small inlet boxes as they can cause surging CDo Splitters at the inlet help prevent spinning ow Turning vanes where R W improves uniformity of ow approaching the fan inlet Inlet boxes should be amply sized CEccentric inlet ow Do ensure inlet air to the fan is evenly distributed Don't Eccentric air distribution at fan inlet diminishes fan performance by up to because the main ow is accelerated through an e ?ectively smaller duct area on one side while turbulence and high intensity pressure uctuations occur on the other Noise level is also increased Do Rated fan performance is only achieved when air ows evenly into the fan impeller CBends on fan discharge Bends near fan discharge should be in the direction of wheel rotation to prevent needless pressure loss Don't Air moves faster at the outside of the fan housing and is not evened out before striking the abrupt bend A very high pressure loss results Do Improved discharge arrangement with radiused bends and splitters or di ?erent fan mounting position will reduce system losses CBends should 'rotate' in the same direction as the impeller Inlet plenums Ensure eccentric ow is not caused by inlet plenum Don't With a single width fan the air ow takes a single turn to enter it eccentric ow is created Do Selection of a double inlet fan improves air ow Central positioning of the fan and plenum entry grille will also assist CMotor Position Position the motor of a belt-driven fan such that the belt leaving the motor pulley is uppermost as this will increase belt arc of contact Don't Belt leaving motor pulley is less taut than upper length and the slight sag will reduce arc of contact on the drive pulley CDo Arrangement with the maximum arc of contact