Air Handling Unit Fan Damaged Belt Sheaves

In this case study, we examine a scenario at a manufacturing facility of a large pharmaceutical company, where the facility identified a loose mounting/foundation issue on an Air Handling Unit by leveraging wireless monitoring from Petasense.

In January 2023, the site reliability team received an automated notification from the system that one of their critical AHUs had exceeded a warning alarm threshold for vibration (RMS velocity). The trending data indicated a concerning degradation in the condition of the AHU, including a noticeable increase in vibration baseline that was progressively worsening. The Vibration spectra revealed that the increase was prominent at 2X the fan speed frequency along with a rise in fan running speed harmonics. These trends strongly suggested the presence of looseness and/or wear in the mounting bolts or foundation of the AHU, posing a potential threat to its structural integrity.

To address the detected issue, an immediate inspection was recommended to be scheduled at the site as soon as feasible. Petasense analysts recommended the following process:

1. Perform a comprehensive check of all bolting mechanisms to ensure they are adequately secured
2. Perform a careful examination to identify any signs of damage or deterioration
3. Verify the integrity of the fan bearing supports and inspect the sheaves for any indications of damage
4. Check and correct alignment belt condition and tension to ensure the AHU’s optimal functioning.

Upon inspection, issues were detected in the belt sheaves. It was concluded that over time the sheaves had been damaged due to misalignment or a combination of faults. The replacement of the motor and fan sheaves resolved the AHU’s vibration problem. This successful resolution validates the importance of proactive maintenance and timely interventions in ensuring the reliability and longevity of AHU systems.

air handling unit belt sheaves damage vibration