Predicting the Future with Condition Monitoring

The “P-F Curve” displays a typical machine’s gradual degradation in performance over time,.

By Nicholas Hearn (JEG Diageo team)

Through a variety of techniques, including vibration analysis, lube oil analysis and thermography; Jones Engineering’s Condition Monitoring technicians are helping clients to predict and prevent equipment failure and downtime. Unfortunately, while these methods are perfectly suited to identifying faults in equipment and machinery several weeks (and even months) before they could be detected by sight or sound; they can’t be used to foresee next week’s Euromillions results!

Condition Monitoring
The primary purpose of Condition Monitoring (CM) is to enable faults to be identified at an early stage of developing and to allow corrective actions to be planned and implemented according to the current physical condition of the machine. This practice is known as Condition-Based Maintenance (CBM) and forms a cornerstone of “Predictive” maintenance philosophies. The alternatives to CBM are Time-Based (or “Preventive”) maintenance, where work that is known to help prolong the life of machinery (e.g. greasing bearings and gearboxes) may be completed every week/month/year in order to discourage faults from developing; and “Reactive” maintenance, where faults are fixed only after a failure has occurred.

The “P-F Curve” (shown above) displays a typical machine’s gradual degradation in performance over time, from the moment when a fault occurs that has the “Potential” to cause a failure (P), to when a “Functional” failure occurs (F) and the machine is no longer capable of operating as it is required to. The time axis on this graph is arbitrary, as it will differ depending on the machine and fault; but the points along the curve, which represent ways the fault can be detected as it develops, give an accurate representation of how Condition Monitoring techniques can give an early warning that a component may not be functioning correctly. Different condition monitoring techniques may be applied to a variety of equipment and machinery and each has its own merits and restrictions:

• Vibration Analysis is particularly suited to diagnosing faults in rotating equipment, but requires specialist equipment and training in order to collect and analyse data. Faults are diagnosed through identification and comparison of patterns in the frequency of the vibrations and may also be identified by trending the overall vibration levels over time. The most common faults detected through vibration analysis are: imbalance, misalignment, component looseness and bearing failures. It can also pick-up faults in electrical and belt-driven machinery and detect damage to pump vanes and fan blades.

• Lube oil sampling may be performed with limited training or instruction and it is often possible to tell if the oil has been contaminated simply by looking at it; however, specialist laboratory analysis is required to determine the exact nature of the contamination. Examples of faults that can be identified through oil analysis include: bearing/gear wear, product/water ingress/contamination and excessively high/low operating temperatures.

• Thermography uses infrared thermal imaging to accurately record surface temperature and has a broad range of applications; the equipment is readily available, but again requires specialist training in order to be deployed effectively. It can be used to detect: overheating/overloaded parts and equipment; leaks and blockages in pipework; and degradation of internal/external coatings and insulation.

Condition Monitoring – Five Ws

• What is it ?
• Why do we do it ?
• Who does it ?
• When do we do it ?
• Where are the benefits ?