We live in a remarkably high-tech world. Despite this, many companies know alarmingly little about the state of their compressed air system. This ignorance invariably costs them money as, fearing the worst, they tend to replace parts well before they need to—paying not only for the parts themselves, but also for their installation and the downtime this entails. For this reason, CRU AIR + GAS is highlighting an approach to maintenance that helps companies avoid this problem—condition-based monitoring, also commonly called condition-based maintenance.

What is condition-based monitoring/condition-based maintenance?

Condition-based monitoring is a maintenance strategy that continuously monitors the condition of an asset using different types of sensors and uses the data obtained from them to monitor the asset in real time. By closely monitoring an asset, maintenance teams can identify when it is about to fail or has already failed. With condition-based monitoring, maintenance is done only when the actual condition of an asset dictates that it be done, eliminating costly and unnecessary maintenance.

Condition-based monitoring vs. predictive maintenance

Condition-based monitoring and predictive maintenance have many similarities, but they are not the same. Condition-based monitoring is focused on the real-time performance and condition of an asset and it tells you precisely when parameters have been exceeded. The simplest example of this would be a sensor reading from an oil pump showing a significant drop in pressure, a telltale sign that a component has failed.

Just like condition-based monitoring, predictive maintenance uses real-time and predictive analysis to figure out when an asset will fail. Let’s return to the example used to above regarding oil pump sensor readings to illustrate how predictive maintenance differs from condition-based monitoring. The main difference relates to timing. Condition-based monitoring lets you know the condition of equipment right now whereas predictive maintenance lets you know what it’s condition might be at a certain point in the future.

Types of condition-based monitoring

A condition-based monitoring system makes sure that all parts of a system, such as a compressed air system, are operating efficiently and helps those running it accurately predict when problems may occur. The key to this approach is the use of unique algorithms that assess service intervals based on the actual maintenance needs of an asset, not just theoretical maintenance needs based on averages within a specific industry.

There are three main levels of condition-based monitoring/maintenance.

1.     Lubricant condition-based maintenance: Lubricants are the lifeblood of most systems, including compressed air systems. By checking lubricants through sampling and lab testing it is possible to determine contamination levels and the quality of the fluids, including their metal content. This information is critical in optimally timing oil changes. If you change the oil too early you are wasting money; if you change it too late you are compromising the life expectancy of the compression element, known as the airend. In a compressed air system, high levels of metal in the lubricant suggest deterioration of the rotors, bearings, heat exchangers or other passages the oil has contact with.

2.     Mechanical condition-based maintenance: Shock pulse monitoring helps assess vibration and noise levels, which gives maintenance teams valuable insights into the condition of the airend. This technique employs instruments and sensors to precisely measure vibration and noise levels. High readings can indicate worn bearings or rotors. By getting a clear picture of wear trends through vibration monitoring and detecting metals in the oil you can develop correlations and predictive models to assess how much useful life an asset is likely to have.

3.     Pneumatic condition-based maintenance: This approach examines air quality in a system to ensure the system is operating at optimal efficiency. One pneumatic condition-based maintenance technique is to conduct air system modeling and simulation (ASMS). This is done by creating an electronic model of an entire compressed air system, from compressors and accessories to the piping distribution network and point-of-use devices. This helps plants better understand their compressed air system by testing the compressed air within it, air pressure in the piping, air flow levels, humidity and more. ASMS can also highlight where additional equipment may be beneficial. If testing reveals excessive humidity in the air, the incorporation of dryer technology may be recommended.


To learn more about the use of condition-based monitoring for your compressed air system, click here to contact us. We at CRU AIR + GAS would be honoured to work with you to implement this maintenance strategy to help you maximize uptime—and the profitability of your operation.