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PRUEFTECHNIK Canada Service Team recently conducted a balancing job for 5 exhaust and circulation fans using the VIBXPERT II data collector and analyzer. We are glad to share the details and successful outcome of  this job.
 
Unbalance is the most common cause of increased levels of vibrations. For several years, the vibration behavior of the fans had been neglected at a plant that manufactures egg cartons. No predicitive maintenance (PdM) program was in place but eventually the new realiability engineer decided to reduce the vibrations of this equipment by getting them analyzed. After performing several diagnostic tasks, the sources of vibration could easily be detected.
 

PT Engineer using VIBXPERT II

VibXpert balancing fans
VIBXPERT II and accelerometers mounted on fan's bearings

 
 
 
 
 
 
 
Accumulation of dust and dirt on all rotor blades lead to a 1x vibration peak in the velocity spectrum. The sine waveform and phase analysis confirmed the results. A static unbalance was the reason for the increased vibration.
The balancing procedure was successfully performed on-site during the next shutdown phase of the plant. VIBXPERT II and OMNITREND software were used for the balancing runs. The static unbalance requires only a one-plane balancing procedure which was ideal for those fans. The accelerometers were attached to the non-drive end (NDE) bearing in horizontal direction. VIBXPERT offers a “second plane control feature” where the second accelerometer contorls any negative influence on the NDE bearing during trim runs. This ensures that the vibration on both bearing will be equally reduced and balanced. The target quality grade of 6.3 according DIN ISO 1940 was easily reached.
 The plant went back online a few days later and the customer was extremely satisfied with the result of this service, who later stated:

“In the last 6 years, I have never seen those fans run so smooth.” 

VXP II Screenshots
Screenshots of VIBXPERT II handheld device

OMNITREND Software
"Before and After" Results Screenshot using OMNITREND SW

Special thanks to PRUEFTECHNIK Canada for sharing this successful story with us.

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, , by Yolanda Lopez