A major textile manufacturer located in the southeastern United States depends on eleven Sullair 400 HP oil-flooded rotary screw air compressors to keep production in its plant running at full capacity. According to the facilities maintenance manager, it is nearly a full-time job for one maintenance technician to perform all the preventive maintenance tasks specified by the compressor manufacturer. Of these recommended tasks, the most time consuming and most costly is changing the compressor's oil and separators at their regularly scheduled intervals. For each of the 11 compressors, the service technician spends most of an eight-hour shift draining and filling each compressor with 55 U.S. gallons (208.2 liters, 452 pounds) of Sullube PAG/POE oil, and then disposing of an equal amount of used, hazardous waste oil and bulky, messy separators.
One of the major challenges when changing the oil in a compressor of this size is ensuring that all of the old, acidic oil is sufficiently drained so as not to precontaminate the new oil. In larger compressors like these, there are numerous low points and dead zones that can trap as much as 25 percent of the compressor's total fill volume with highly oxidized and acidic oil. Once the new oil is added and the compressor is running, the residual oil in the compressor immediately contaminates the new charge of oil with acids and other catalysts which dramatically reduce the new oil's useful service life.
Removing those last few gallons of contaminated oil is difficult and time consuming. Most compressor users and compressor service companies skip this extra step yet are unaware of the costly and potentially harmful consequences. Such was the case with this textile company who, after performing what it believed to be a thorough oil drain and fill, had its oil tested and was surprised to learn that the brand new oil, now in the compressor, had a baseline acid number (AN) of 0.70 (condemning AN limit = 1.0). The AN of the new oil from the drum was 0.10).
This "brand new oil", with fewer than 200 hours in service, was well on its way to being condemned and had an estimated remaining life of fewer than 3,000 hours. This oil analysis demonstrated that residual oil contamination had reduced the "new oil's" service life by more than 60 percent!
Because it is impossible to completely eliminate residual oil contamination, this user decided to install a Fluid Metrics Compressor Oil Purifier (COP) to reduce the acidic and solid catalytic contaminants left behind by the old oil. The COP's ion exchange technology and ultra-fine filtration was perfectly suited to remove the acids and catalytic solids, extend the user's fluid service life, and reduce the harmful effects of residual oil contamination. Results
Just 30 days after installing the purifier, the customer had its oil retested by an independent oil analysis laboratory. Analysis results revealed that the COP had successfully reduced the oil's baseline AN from a value of 0.70, all the way down to 0.10, the same AN of brand new oil. (Figure 2). Nearly 8,000 hours later, subsequent oil analysis shows the purifier has continued to maintain the oil in like-new condition with acid levels significantly below their initial values. Additional oil analysis results, collected over a longer period of time from an identical compressor with the exact same fluid and oil purifier, demonstrated more than a three-fold increase in oil service life when employing proactive oil maintenance with the COP. Conclusions
Residual oil contamination is a common, and often overlooked problem that negatively impacts compressor fluid health, service life and maintenance cost. Proactive fluid maintenance with the COP eliminates the problems associated with residual oil contamination by continuously removing the acidic contaminants left behind after an oil change. The net result is significantly increased fluid service life, improved fluid performance and protection, and lower compressor operation and maintenance costs.
