Replacing air compressor oil and parts using time based “preventative” maintenance is an outdated, inadequate, and wasteful practice: so why are you still doing it?
Is your air compressor maintenance hurting your company’s bottom-line? Are you maintaining your compressors using the same methods and tools as 20-years ago, 50-years ago? If your company uses oil-injected rotary screw air compressors and follows the manufacturer’s suggested “preventative” maintenance guidelines, then the answer to these questions is an emphatic YES!
According to the Compressed Air & Gas Institute (CAGI), the unbiased authority on technical matters impacting the air compressor industry: “Perceptive management teams recognize that they can no longer be competitive with outdated maintenance practices. The methods, tools and quality of maintenance used in the past are no longer adequate in a contemporary production environment. Good maintenance is a genuine value, especially as it relates to bottom-line results.” CAGI
So, what is THE TRUTH about air compressor maintenance? Consider the following:
1) Time-based Preventative Maintenance is Outdated and Inadequate
When rotary screw air compressors were first introduced back in the 1960’s, times and technologies were dramatically different. Most of the maintenance tools and methods taken for granted today, like the PC, Computerized Maintenance Management Systems (CMMS), oil analysis, vibration analysis, thermography and many more, were all non-existent back then. Without these tools maintenance departments had little option but to follow the time-based “preventative” maintenance (regular oil and parts replacement) recommended by their compressor manufacturer.
Fortunately, there’s been an explosion of technologies developed over the last 50 years to make maintenance and reliability managers’ jobs much easier. Those technologies have rendered many time-based “preventative” maintenance practices inadequate and obsolete. Today there’s a wealth of fluid conditioning technologies and condition monitoring tools that target the root cause of component failures and allow users to optimize their compressors’ reliability at the lowest cost. Additionally, these tools enable “proactive”, “predictive” and “reliability-centered” maintenance strategies that are proven to increase component service life, reduce maintenance frequency, and save you time and money.
2) Time-based Preventative Maintenance is Unreliable and Misguided
The basic premise of time-based “preventative” maintenance (PM) is this: If you replace components at regular time-based intervals (before they fail), you can avoid costly repairs and unscheduled downtime. The problem for rotary screw air compressor users is that the equipment manufacturers’ guidelines dictate WHAT you replace (oil, separators, filters, etc.), and WHEN you replace them. But there’s one major problem with this time-based maintenance strategy. TIME is an inaccurate and unreliable predictor of when compressor oils, separators and other components actually need to be replaced.
Consider for example the typical manufacturer’s recommendation to change your rotary screw compressors’ oil every 8,000 hours, or once a year, whether needed or not. Now consider an actual scenario of two identical air compressors using the exact same oil and operating side-by-side in the same plant. Routine oil analysis indicated that one compressor’s oil had already turned acidic (the leading cause of oil replacement) and needed to be replaced after only 2,000 hours in service. Meanwhile, repeated oil analysis from the second compressor indicated that its oil was perfectly normal and still fit for continued use after more than 60,000 hours in service! This 30-to-1 spread in actual oil service life illustrates just how unreliable and misguided time-based preventative maintenance can be in the real world. There are just too many variables, not the least of which are the compressor’s environment and quality of maintenance performed. These variables have a profound impact on when it’s actually necessary to replace compressor oils and countless other costly components.
3) Preventative Maintenance is a Waste of Time & Money
In the example above, had the user followed their manufacturers’ 8,000 hour time-based recommendation, they were guaranteed to change both compressors’ oil at the wrong time with negative consequences. In the case of the 60,000 hour compressor, an 8,000 hour oil change would have been far too soon. It would have resulted in a dramatic increase in their oil purchases, maintenance frequency, man-hours, and waste oil disposal – by more than 7.5 times! In the case of the 2,000 hour compressor, an 8,000 hour oil change would have been far too late, putting their compressor’s reliability at serious risk from high acids and corrosion. This would ultimately result in higher maintenance costs, repairs, and downtime. Either way, time-based “preventative” maintenance misses the mark and results in a major waste of time and money.
The only reliable method for determining when a compressor’s oil actually needs to be replaced is condition-based oil analysis. Like a blood test for your compressor, oil analysis quantifies the oil’s actual physical and chemical properties and eliminates the guesswork on the oil’s in-service condition. Oil analysis also provides additional valuable information about bearing wear, contaminants, and the oil’s protective additives. When viewed together, oil analysis can alert users to take proactive and/or predictive measures to avoid expensive failures and downtime.
4) Preventative Maintenance is Unsustainable
By design, for time-based preventative maintenance to be effective, the compressor’s oil and other components must be replaced before they fail. Compressor manufacturers want to avoid premature failures and the resultant warranty claims, so their recommended oil and parts change intervals tend to be very conservative and a fraction of their useful life. As a result, perfectly good oil, separators, and filters are routinely and needlessly replaced and discarded. This preventative approach to maintenance generates an excessive amount of environmentally unfriendly waste that requires special handling and disposal. This not only adds time and cost to the maintenance process, but it’s also counterproductive to the emissions goals and sustainability initiatives that most environmentally conscious companies have in place today.
5) Preventative Maintenance Simply Isn’t in Your Best Interest!
Given all the negatives associated with time-based maintenance, it’s worth asking why equipment manufacturers still recommend this practice, especially considering all the new and improved methods available. Manufacturers and their distributors generate the vast majority of their profits from recurring sales of oil, parts, and maintenance service agreements. Obviously, the engine that drives this profit stream is time-based preventative maintenance.
Compressor manufacturers’ Maintenance Manuals, Extended “Warrantees”, and Service Agreements are all designed to promote preventative maintenance. They attempt to lock customers into a steady consumption of expensive oil and parts to keep their recurring sales and profits rolling in. For more than 50 years, it has been in the compressor manufacturers’ best interest to maximize consumption and sales of their highly-profitable oil and parts at their customers’ expense, whether needed or not.
Perhaps the 5 reasons listed above are what the experts at CAGI had in mind when they warned compressor users about outdated, inadequate, and wasteful practices. Maybe now is a good time to rethink your “Preventative” maintenance.
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