What problems can the color change of air compressor oil indicate?
October 02, 2022
Air compressor lubricating oil undertakes the important functions of cooling, sealing and lubrication during the operation of the air compressor, and also has the functions of shock absorption, noise reduction and part of the power transmission.
1. Air Compressor Oil new oil color The new oil color of air compressor oil is mostly light yellow or nearly transparent and colorless. The color and transparency of the Base Oil produced in different regions are more or less different. Therefore, the color of the same type of oil produced by using the base oil in different regions is also There may be differences. For most lubricants, there is no color requirement. As long as the indicators meet the requirements, the initial color of the lubricating oil has no effect on the use effect. Different packaging and storage and transportation conditions will also cause the oil to have different degrees of contact with air and heat sources. When not in use, it has been partially oxidized and combined with additives, resulting in different shades of color. Individual lubricating oils have special requirements for color, which can be achieved by dyeing, but the performance does not change. 2. Challenges encountered in the use of air compressor oil Because the air compressor oil is atomized when it is sprayed into the main engine, and after being injected into the main engine, it will be quickly and completely mixed with the high-temperature compressed gas, and will be rapidly oxidized under the action of high temperature and air, and at the same time, a large amount of saturated steam will act. To the catalytic effect, therefore, the anti-oxidation ability of air compressor oil has become the most tested part. In order to avoid the addition of metal elements to catalyze the air compressor oil, the air compressor oil contains a certain amount of metal passivator, and at the same time, anti-corrosion and anti-rust additives are added, which ensures that the air compressor is in contact with metal throughout the process. The oil remains in a stable state. All of the above will affect the use effect and life of the air compressor oil. In fact, there are many factors that affect the effect and lifespan, but the above are the more important ones. 3. Color changes during use As the air compressor oil is installed and used, the light yellow or nearly colorless and transparent oil gradually becomes darker, and begins to show different color changes. Some air compressor oil is yellow, some is dark red, some is blue, and some is blue. Purple, dark brown or even black. People tend to think that common color changes like dark brown, yellow, etc. are normal, and less common discolorations like dark red, etc. are abnormal. What people overlook is that some abnormal discoloration is often accompanied by other characteristics, such as the air compressor oil becomes milky white or gray, opaque, and at the same time, the viscosity decreases, which means that the water content of the oil is too high and the emulsification is serious. Or blackened, accompanied by a large amount of metal grinding dust, giving off a burnt smell, etc. 4. Reasons for most color changes Due to oxidation and the mixing of various impurities, certain color changes will be brought about, but the main reason for discoloration is due to the effect of antioxidants. The oxidation process is a series of free radical chain reactions. Under the action of heat, light or oxygen, the chemical bonds of organic molecules are broken to generate active free radicals and hydroperoxides. These free radicals can initiate a series of free radical chain reactions, resulting in fundamental changes in the structure and properties of organic compounds. The role of antioxidants is to eliminate the free radicals just generated, or prevent the decomposition of hydroperoxides and prevent the chain reaction from proceeding. 5. Special Color Change Reasons In addition to the causes of discoloration described above, there is a special case where the color of the oil changes to green. After the follow-up study of many cases, it was found that when the oil turned green, the acid value was detected to increase and the increase was large. The acid value will be allowed to reach more than 2mgKOH/g, which is 10 times higher, indicating that the deterioration of the oil has been very serious.
Summarize 1. The initial color of the oil does not affect the performance of the product 2. The same type of lubricating oil made from base oils of different origins may also have color differences 3. The discoloration of air compressor oil is mainly caused by antioxidants 4. As long as the oil is clear and there is no precipitation, discoloration during use is normal in most cases 5. The copper in the oil exceeds the standard, which makes the oil green. The main reason is related to pollution, especially the mixing of particles with a porous structure.
