API Plant HVAC Motor Bearing Deterioration


This case study is from an API pharmaceutical plant located in Singapore, Asia. The Eastway Safeguard® online monitoring system was installed on the manufacturing plant’s critical Heating Ventilation Air Condition (HVAC) system in 2018. The Eastway Safeguard® continuous vibration monitoring system replaced their pre-existing manual vibration data collection programme.

This API plant have in-house vibration analysis experience within their maintenance team and the Eastway team work closely with them – supporting them 24/7 with automatic alerts, in-depth vibration analysis diagnosis and advice on the optimal maintenance decisions for each asset. 

Prior to the Eastway Safeguard® system installation, vibration sensor selection and positioning was carefully reviewed.

Case Description

During the commissioning process for the Eastway Safeguard® system, it was noted that the vibration was higher than expected from one of the HVAC Fan motors – API AH5005 Supply Motor 1. This HVAC unit has two supply motor fans and two exhaust motor fans and 3 vibration sensors were fitted per motor fan.

Machine Name
API AH5005 Supply Motor 1
DescriptionDirect Drive Fan Motor
Motor Plate RPM 1460
Bearing - NDE6210 ZC3
Bearing - DE6210 ZC3

Initial analysis of the vibration data indicated excessive Acceleration vibration (g RMS) from both motor bearings – Motor Non-Drive End (MNDE) and the Motor Drive End (MDE). Further investigation of the vibration data was completed by Eastway. As an example of this analysis, the vibration Fast Fourier Transform (FFT) spectra and time waveform signatures were examined. It was concluded that the vibration patterns demonstrated evidence of Motor Bearing deterioration. See Figure 1 for Motor Drive End (MDE) Acceleration FFT spectra (g RMS) and Figure 2 for MDE Time Waveform (g RMS) both from 15 July 2019.

Figure 1 MDE FFT 15 July 2019

Figure 2 MDE Time Waveform 15 July 2019

Based on these initial observations and following discussions with the API plant personnel, a decision was made to continue to monitor the vibration trends and patterns closely, to determine when Motor bearing replacement would be required.

In September 2019, in addition to gradually increasing Acceleration levels, further deterioration was detected with an increase in vibration Velocity (mm/s RMS) at the MDE.. The vibration patterns were now showing evidence of impacting with varying low frequency magnitudes within the vibration waveform, indicating bearing equilibrium was not steady. See Figure 3 for MDE Velocity Trend increasing and become unstable in September and October 2019.

Figure 3 MDE Velocity Trend Jul 2019 – Jan 2020


Based on this additional evidence, motor bearing replacement at the next downtime opportunity was recommended.

Action Taken:

Following this recommendation, a downtime window for API AH5005 was arranged with the API plant production team for 22 October 2019. At this downtime, the API plant maintenance personnel removed API AH5005 Supply Motor 1. They reported substantial wear evident on the Motor Bearings and they fitted a new Motor in its place. Eastway were in close contact with the API Maintenance team and supporting the works by closely monitoring the vibration levels once the API AH5005 restarted.

It was confirmed that following this maintenance work, the vibration levels across the machine reduced significantly and have remained at low magnitudes since. See Figure 4 for MDE Acceleration (g RMS) trend from 01 July 2019 to 31 Dec 2020, Figure 5 for MDE Velocity (mm/s RMS) trend from 01 July 2019 to 31 Dec 2020 and Figure 6 for MDE Acceleration (g RMS) FFT Waterfall comparison from Sept 2019 to March 2021.

Figure 4 MDE Acceleration (g RMS) trend from 01 July 2019 to 31 Dec 2020

Figure 5 MDE Velocity (mm/s RMS) trend from 01 July 2019 to 31 Dec 2020

Figure 6 MDE Acceleration (g RMS) FFT Waterfall comparison from Sept 2019 (rear) to March 2021 (front) 18 months post maintenance

Results: Estimated* cost savings associated with avoidance of unplanned downtime, emergency repair costs & secondary damage:

Downtime avoided: 5 hours
Downtime cost per hour €20,000
Potential Batch Loss ++++
Total Savings: €100,000+++