most frequent installation errors

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• unfavourable design
• grille forgotten
• disturbed flow-in
• disturbed flow-off
• flexible connections too long/bad aligned
• too steep diffusor in front of a fan
• asymmetric confusor in front of a fan
• elbow before and behind the fan
• swirl at the fan inlet
• elbow at the fan inlet
• elbow at the fan outlet
• unreasonable pressure loss at axial fans
• unreasonable pressure loss at centrifugal fans
• unfavourable duct design

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unfavourable design

Unfavorable	Optimal

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grille forgotten

false	correctly

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disturbed flow-in

bad	better (min. space 1xd)

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disturbed flow-off

bad	better (min. space 1,5xd)

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flexible connections too long / bad aligned

bad / stall!	good

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too steep diffusor in front of a fan (aperture angle max. 7°)

bad / stall!	better

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asymmetric confusor in front of a fan

bad / stall!	better

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elbow before and behind the fan

bad	better

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swirl at the fan inlet

bad	better

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elbow at the fan inlet

bad	good

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elbow at the fan outlet

bad	better  |  good

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unreasonable pressure loss at axial fans

bad	better  |  good

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unreasonable presure loss at centrifugal fans

bad	better  |  good

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unfavourable duct design

bad	better  |  good