Air compressor lubricant performance requirements

1. High quality base oil

   The base oil of compressor oil can be divided into two categories: mineral oil type and synthetic oil type. The production of mineral oil-type compressor oil is generally obtained by solvent refining, solvent dewaxing, hydrogenation or clay supplement refining to obtain the base oil, and then add a variety of additives to blend.

  The base oil of compressor oil generally accounts for more than 95% of the product oil. Therefore, the quality of the base oil is directly related to the quality of the compressor oil product oil, and the quality of the base oil is directly related to the depth of refinement. The base oil with deep refined depth has less heavy aromatics and gum content. Low carbon residue results in better sensitivity to antioxidants and high quality base oil. It has a low tendency to deposit carbon in the compressor system, has good oil-water separation, and has a relatively long service life.

   Synthetic oil base oil is a lubricating oil made from organic liquid base oil obtained by chemical synthesis and then blending or adding various additives. Most of its base oils are polymers or high molecular organic compounds. There are many types of synthetic oils. The synthetic oils used as compressor oils mainly include synthetic hydrocarbons (poly-α-olefins), organic esters (diester), polyalkylene glycols, fluorosilicone oils and phosphate esters. The price of synthetic oil compressor oil is much more expensive than mineral oil compressor oil, but the comprehensive economic benefits of synthetic oil still exceed that of ordinary mineral oil. It has oxidation stability, low carbon deposition tendency, can be lubricated beyond the temperature range of ordinary mineral oil, has a long service life, and can meet the requirements of use that ordinary mineral oil compressor oil cannot withstand.

  2. The base oil fraction should be narrow

  The study of compressor oil conditions believes that improving the composition of base oil is a key factor in improving the quality of compressor oil. After the compressor oil blended by the light and heavy components is injected into the compressor cylinder, the light component in it leaves the working part early due to excessive volatility and affects the lubrication effect, while the heavy component is poor in volatility. After the work task, you cannot leave the work area quickly, and carbon deposits are easily formed under the action of heat and oxygen for a long time. Therefore, under such working conditions, the lubricating oil should choose narrow-fraction component oil, and should not choose component oil mixed with multiple distillates.

   No. 19 compressor oil is prepared with a wide distillate oil containing a large amount of residue components, and the compressor has a large amount of coke during use. Therefore, to improve the quality of compressor oil, the residue components in No. 19 compressor oil should be removed and narrow-cut base oils should be used.

  3. The viscosity should be appropriate

  Under the condition of dynamic lubrication, the thickness of the oil film increases with the viscosity of the oil, but the friction force also increases with the viscosity of the oil. Lubricating oil with too low viscosity is not easy to form a strong enough oil film, which will accelerate wear and shorten the service life of parts. On the contrary, if the viscosity of lubricating oil is too high, it will increase the internal friction and increase the specific power of the compressor, which will increase the power consumption and fuel consumption. It will also be in the piston ring groove, on the valve, in the exhaust passage, etc. Formation of deposits. Therefore, choosing the right viscosity is the primary issue for the correct selection of compressor oil. Tests by have proved that using the same test conditions on the same type of compressor, the use of lower-viscosity grades of oil can reduce the specific power of the compressor by up to 10% compared to the use of high-viscosity grades. There was no significant difference in the amount of wear. Therefore, under the premise of ensuring lubrication, choosing oils of suitable viscosity grades has a very important impact on energy saving and reliable operation of the compressor.

  4. Better viscosity-temperature performance

  The oil-injected internal cooling rotary air compressor is repeatedly heated and cooled during operation. Therefore, it is required that the viscosity of oil products should not change too much due to temperature changes, and should have good viscosity-temperature performance. The viscosity index of the refined compressor oil is above 90.

  5. The flash point should be appropriate

   Flash point refers to the temperature at which the vapor pressure formed by heating the oil under atmospheric pressure reaches the lower limit concentration ignited with an open flame. If the flash point is too high, the oil fraction will be heavy, the viscosity will be high, and the content of asphaltene will be high, and it will be easy to deposit carbon during use. If one-sided pursuit of high flash point compressor oil, it will become an unsafe factor. Therefore, the flash point of the compressor oil should be suitable.

   The flash point is only one of the safety indicators for the use of oil. The flash point of compressor oil is generally controlled above 200 ℃ and can be used safely.

   6. The tendency of carbon deposits to be small

   The anti-coking tendency of compressor oil is crucial to the reliable operation of compressor oil. In actual industrial use, it is not uncommon for large and medium compressors to catch fire and explode due to carbon deposits.

  The main substances that easily form carbon residue in oil are asphaltenes, colloids and polycyclic aromatic hydrocarbons. Most of the above substances can be removed from the lubricating oil after deep refining. Generally, low-viscosity and highly refined lubricating oil has a low carbon residue value and is not easy to deposit carbon during use. Therefore, high-quality L-DAB compressor oil should be selected from highly refined narrow-cut base oil without residue (bright oil). Additives should also try to choose ash-free additives