There are three common management methods for replacing blower lubricating oil, each governed by strict operational standards:
① Scheduled replacement: Oil is changed based on a set time interval (e.g., every three months). Once the deadline arrives, the oil is replaced entirely, regardless of its condition. While simple and conservative, this method can lead to waste and increased operating costs.
② Scheduled replacement based on oil quality: Oil is changed by referencing a standard interval while also considering the actual condition of the oil. For instance, the interval might be six months under low-contamination conditions (minimal dust) and three months under high-contamination conditions. If the oil darkens, becomes cloudy, or shows signs of sludge deposits and solid particles, the replacement interval should be shortened further.
③ Quality-based replacement: Oil is changed based on its performance characteristics. If quality indicators exceed permissible limits, the oil is replaced immediately, regardless of how long it has been in use. This method is cost-effective but makes accurate assessment more challenging.
So, how can the quality of the lubricating oil be assessed? Regardless of the replacement method used, the goal is to ensure the oil maintains its required performance. The following simple methods can be used to evaluate oil quality:
① Lubricating oil undergoes oxidation and deterioration due to exposure to air and other media during use. To gauge the extent of this deterioration, take some sludge from the bottom of the oil tank and rub it between your index finger and thumb. If there is significant sludge but low adhesiveness, the oxidation is likely mild; the oil is simply dirty and requires filtration. If the substance feels gummy and highly adhesive, the oil has deteriorated significantly and is no longer suitable for use.
② Mechanical impurities in the oil—such as suspended matter or insoluble particles like dust, sand, and metal fragments—can damage the lubricating oil film and accelerate wear. Once the concentration of these impurities reaches a certain level, the oil should no longer be used. Based on experience, if the oil has turned black and its color does not improve significantly after filtration, it should be replaced.
③ Moisture increases the corrosiveness of the oil and accelerates its aging; it also promotes bubble formation, causing the oil to lose its lubricating properties. Therefore, moisture content must be controlled. High-quality lubricating oil should be free of moisture. In practical applications involving water cooling, the infiltration of cooling water can cause the lubricant to deteriorate and fail. To check for the presence of moisture, one can dip a piece of clean, dry cotton waste into the oil and ignite it; if water is present, a popping sound or a flash will occur.