(20 min.) Case Study: Interval Time & Location of The Vibration Data Acquisition in a Cooling Tower´s Gearbox

Oscar Medina, Reliability Engineer & Planner, Pfizer (Adv.)


As technician, engineer, maintenance and reliability professionals, we are responsible for developing and implement a great condition monitoring program. The main idea is to move from reactive to predictive maintenance and vibration analysis is one of the most powerful technics we can use to reduce downtime and increase the asset availability.

First, How often? every day or every once in a week / month / year? I would say that it depends on the accessibility to the machine, how critical it is and the available resources in the plant to do the job.
Know, it´s time for “the right location”. In a normal routine you can take data for every point you want to (while getting securely access) but what happen with those you cannot access and need to put a permanent sensor, where would you install it? For someone the answer could be every easy, horizontal coupling side of the machine (driven end side).

In a petrochemical refinery there are four cooling towers in a Motor – Gearbox – Fan arrangement, each cell is monitored through a vibration sensor positioned on the outer gearbox shaft.
For almost two years this equipment had been presented high vibration for diverse events. With the pass of the months the maintenance personal adopted a policy to verify the machine´s condition, taking vibration spectrums, just when it was down because of the activation of the very high vibration alarm (they by passed the alarm and started up the cell again).

One day, as expected, was too late to start it again and take a measurement, finally the disaster happened, a fan blade of one of the towers broke suddenly causing damage to others fan blades, motor gearbox coupling and difussor protection.

After the collapse a series of analysis, actions and recommendation were made to avoid things like this happen again.


  1. How important is select a great interval time between measurements and taking gearbox vibration data in more than just one location with a permanent sensor.
  2.  Analyzing your maintenance tasks to improve your CBM program and prevent catastrophic failure.
  3. Avoid those repetitive actions from unrepaired mistake that lead us to complacency.


Oscar Medina was born in Venezuela, Mechanical Engineer from University of Zulia. Winner of the Mobius Institute scholarship in 2018 getting certified as Vibration Analyst CAT II. Has been working for the petrochemical, oil & gas and pharmaceutical industry as reliability and maintenance engineer focus primarily on rotating equipment developing, improving and implementing condition based maintenance technics.