How often should oil lubricated air compressor oil be replaced?

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Generally speaking, technicians need to regularly sample the air compressor lubricating oil to determine whether the oil needs to be changed. Because the structural forms of compressors are different, a unified compressor lubricating oil change time cannot be generally determined. Even if the structure is the same, the oil change time will be different due to differences in the compression medium, operating conditions, quality of the compressor oil, and working environment. However, we can all use scientific methods, a large number of experiments and practical experience to determine the oil change indicators, that is, frequently observe the color and cleanliness of the oil during compressor operation, and regularly sample and analyze the oil's viscosity, acid value, n-heptane insoluble matter and other physical and chemical properties. If the oil change indicator is reached or exceeded, all or part of the oil should be replaced and replenished with new oil. Under normal circumstances, the oil in the oil cooler, oil-gas separator and oil system should be replaced every 2000-4000 hours of continuous working time, and the filter should be replaced or cleaned at the same time. For best results, the lubricating oil area must be thoroughly cleaned. Cleaning steps include draining the old oil, removing sediments, and flushing with new oil. After cleaning the system, if necessary, drain the running-in oil after 150-250 hours of running-in. We analyzed the air compressors of the two structures respectively. If the following conditions occur, oil change should be considered: 1. Reciprocating air compressor oil 1. The oil changes color, or the color deepens by more than 4 levels; 2. The acid value exceeds 0.5 mgKOH/g; 3. The viscosity changes exceeds ±15%; 4. The n-heptane insoluble matter exceeds 0.5%. 2. Rotary air compressor lubricating oil The oil change indicators of rotary air compressor (SH/T 0538-2000) are shown in the table below. Referring to the table below, if one of the following indicators is reached, replacement of new lubricating oil should be considered. Things to note: 1. The lubricating oil used in the air compressor is a special air compressor oil provided by the lubricating oil manufacturer. The lubricating oil has three functions: cooling the compressed air, sealing the rotor meshing gap, and lubricating the bearings, shaft seals and gears. In fact, most of the oil is used to cool the compressed air. The oil that enters the compression chamber to cool the compressed air is in direct contact with the air at an operating temperature of nearly 100 degrees and is easily oxidized and deteriorated. Therefore, the cooling lubricating oil is required to have good antioxidant properties. In addition, the contact between air and oil will cause part of the pressurized air to dissolve into the oil. After the oil with dissolved air chokes into the separator, once the pressure drops, the pressurized air dissolved in the oil will immediately expand rapidly to produce a large amount of foam, which seriously affects the performance of the oil. Therefore, the lubricating oil is required to have the characteristics of rapid defoaming and minimum air solubility. 2. The lubricating oil used in air compressors is formulated with a special formula. It can not only give full play to the three major functions of lubricating oil, but also has the characteristics of anti-oxidation, non-foaming and minimal air solubility. 3. How long the lubricating oil needs to be replaced after use should be determined according to the actual situation. Generally speaking, the lubricating oil must be replaced after 2,000 cumulative operating hours, but it also depends on the customer's usage and frequency of use. Sometimes, although the cumulative operation hours are less than 2,000 hours, the oil has not been changed for half a year, and the lubricating oil must be changed. Otherwise, the quality of the lubricating oil will decrease and it is easy to cause a high-temperature trip failure. As the oil quality declines, if the lubricating oil is not replaced in time, it is easy to cause damage to the compressor head.