Put more succinctly, Condition Monitoring (or “CM”) is the process of monitoring a parameter (or parameters) which reflect the condition or performance of a piece of equipment, in order to identify any significant degradation, which is indicative of a developing fault, or an unacceptable drop in equipment performance.
The key word is ‘monitoring’ in the context of condition monitoring. This conditional monitoring task requires regular checks of the selected key parameters, which have been selected, to be in a position to identify the onset of a failure or drop in performance. Then subsequently schedule the appropriate maintenance intervention, in a timely manner, to prevent failure and avoid its consequences. CM, which is a non-invasive technique, which is usually employed on rotating equipment such as: pumps, compressors, fans, turbines and electric motors etc. The ultimate aim of condition monitoring is to only perform maintenance work only when necessary.
The most common technique used in condition monitoring is vibration analysis, where measurements are taken on machine bearing housings with transducers – which are normally accelerometers, in triaxial directions, as shown below. This system employs portable battery-powered instruments called data collectors/analysers; this methodology is referred to as an “offline” system, using instruments such as the Adash A4900 VA4 Pro 4-channel unit below.
However, on more critical machines, eddy-current displacement transducers are used, which directly observe the rotating shafts to measure the radial and axial displacement of the shaft as shown below. These displacement transducers are permanently mounted on the machine housings, and monitor the condition of the machine on 24/7 basis, and is known as an “On-Line” system.
The signals from these eddy current ‘prox probes’ are fed back to a permanently installed rack system, such as the Sensonics G3 system below, which is designed to protect these high capital investment and production critical machines from failure.
Other Condition Monitoring Techniques
There are other condition monitoring techniques to consider, and machines may have one or more of these applied, depending on its criticality and likely modes of degradation and the cost of failure. These other CM techniques (in addition to vibration analysis) include:
- Spectrographic Lube Oil Analysis
- Performance analysis
Lube oil analysis is perhaps the next most widely employed CM technique after vibration analysis, and perhaps, more increasingly, thermography and performance analysis.
When you call it a day on the plant, is your mind more at ease thanks to condition monitoring?
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