Compressor lubricating oil is referred to as compressor oil and air compressor oil for short, also known as: coolant, super coolant and lubricating coolant, cooling lubricating fluid and so on. It acts as a kind of "compressor running blood" and plays an important role in reducing friction and wear. In the oil-injected screw compressor, it also plays a role of sealing, absorbing heat and absorbing dust in compressed air.
Life and oxidation of compressor oil


The life of compressor oil is mainly determined by the degree of oxidation and the consumption of additives, and the degree of oxidation is the most important factor.


The oxidation process of lubricating oil is a complex process in which hydrocarbons interact with oxygen. Through the action of active free radicals and oxygen, alcohols, aldehydes, ketones, and acid intermediates are first formed, and then further oxidized to generate hydroxy acids and ester compounds. As a result of the oxidation, the molecular weight of the product continues to increase, the structure tends to be complex, and eventually colloids and precipitates are formed.


氧化 There are two directions of oxidation in the use of lubricating oil: one is the intermediate product that generates acidic substances (such as carboxylic acid, hydroxy acid, asphaltic acid, etc.) and esters, and the final product is carbon blue. The other direction is to produce gum, asphaltene, and the final product is semi-oily gum. Hydroxy acid, semi-gelling, asphaltic acid, these components are slightly soluble in lubricating oil, and the precipitated part is viscous substance. Easily adheres to metal surfaces and converts to paint films at high temperatures. Asphaltenes, semi-oleogels, and carbon cyanides are suspended in the oil as dark brown or black solid powder-like fine particles. When aggregated into large particles, they can precipitate from the oil.


It can be seen that after deep oxidation of the lubricating oil, the oxygen content of the internal chemical components increases, the molecular weight increases, and the hydrocarbon compounds become non-hydrocarbon compounds; the appearance becomes darker, the precipitation increases, and the corrosiveness increases, making the lubrication The performance of the oil decreases.


In addition to its chemical composition, the oxidation of lubricating oil is also closely related to the use conditions, such as the temperature, the air pressure and the partial pressure of oxygen, and the strength of the catalytic action of the metal in contact. Among them, a very important factor is the catalytic effect of metals. Practice has proved that many metals have a catalytic effect on the oxidation of lubricating oil. Of the commonly used metals, copper has the largest catalytic effect on lubricating oil, especially when water is present. The main reason for metal catalysis is to promote the decomposition of peroxides to generate free radicals, thereby accelerating the oxidation reaction.