4
MPA IO&M
B51223-005
Isolation
Structural bases must be sturdy enough to prevent flexing
and vibration. Design, fabrication, and installation of the
isolation base are the customers responsibility.
After the fan, isolation base, and isolators are installed, the
entire assembly must be leveled. Floor mounted fans should
be installed on a flat, level, rigid foundation.
Installation
Bolt the fan to the structure and adjacent fans using the
inlet and outlet mounting flanges. The first row of fans should
be securely installed before installing the second row of fans.
Cook does not recommend lifting and moving assembled
MPAs, as this may cause bending, distortion, and lead to
component misalignment.
A
(top, bottom, and side connections)
Problem and Potential Cause
Air Capacity:
• Resistance of system not at design rating. If resistance is
lower than expected airflow can be higher and horsepower
can be lower. If resistance is higher than anticipated, air
volume will be down.
• Fan speed is not at design speed.
• Air density not at design values. Also check air performance
measurement techniques / procedures.
• Mechanical air devices (e.g. dampers), are closed or plugged.
Also check filters.
• Impeller mounted improperly or is rotating in reverse.
• Parts of system or fan have been damaged or need cleaning.
Noise:
• Fan is not at design point of operation. Fan forced to operate
in an unstable flow region.
• Bearing failure. Check bearings.
• Supply voltage high or inconsistent supply frequency.
Adjustable frequency controllers can generate motor noise.
• Objects which are installed in a high velocity airstream can
generate noise. This includes flow sensors, turning vanes, etc.
• Non-uniform fan inlet conditions.
• Acoustics or sound measurement procedure incorrect.
Vibration:
• Misalignment of drive components.
• Poor foundations or mounting structure (resonances).
• Foreign object trapped in rotating components.
• Damaged rotating components.
• Broken, loose or missing setscrews.
• Loose bolts.
• Vibration transmitted by another source.
• Water accumulating in airfoil blades.
•
Fan is operating in stall or unstable flow region.
NOTE: All MPA’s are factory balanced prior to shipment. Improper
handling and movement of the fan during shipment may cause the
rotating assembly to shift out of alignment. Balance should be checked
once the fan is installed or if the motor and wheel have been removed
or replaced. If a final trim balance is required, it is the end user’s
responsibility to bring the fan back to factory specifications (0.15 in/
sec Max). Final trim balancing is not the responsibility of Cook.
Foundation
Critical to every fan installation is a strong, level
foundation. Fans mounted to or within a structure should
be placed as close as possible to a rigid member such as a
wall or column. The structure must be designed for rotating
equipment; static design for strength is not sufficient to
insure proper operation. Structural resonance should be at
least 20% above the maximum fan operating speed.
Any ducting should have independent support; do not use
the fan to support ducting. Isolating the fan from duct work
with flex connections eliminates transmission of vibration.
Intake Side
Supply Side
