According to the structure of the compressor, air compressor oil is divided into two types: reciprocating air compressor oil and rotary air compressor oil, each has three levels of light, medium and heavy load. Air compressor oil can be divided into mineral oil compressor oil and synthetic compressor oil according to the type of base oil.

Air compressor oil is mainly used for the lubrication of the moving parts of the compressor cylinder and the exhaust valve, and plays the role of rust prevention, corrosion protection, sealing and cooling.

Since the air compressor is always in an environment with high pressure, high temperature and condensed water, the air compressor oil should have excellent high temperature oxidation stability, low carbon deposition tendency, suitable viscosity and viscosity-temperature performance, and good Oil-water separation, anti-rust and anti-corrosion properties, etc.

Important indicators of air compressor oil

Flash point: The temperature at which the flame flashes within three seconds when the oil is in contact with the flame.

Ignition point: The temperature when the oil is ignited.

Viscosity: At 40℃, the oil flow rate, screw air compressors are generally No. 46, only a few brands of air compressors use No. 32. To test whether the oil is oxidized or whether it has reached the end of its service life, it depends on the change in viscosity. Generally, mineral oil cannot exceed 15%. If it is used for a long time, it will gel or form carbon.

Viscosity Index: The index of the viscosity of an oil product being changed by temperature changes. The higher the better, for example, the index of mineral oil is generally within 120.

Pour point: The lowest temperature at which the oil is kept flowing. The lower the pour point, the better. For example, the pour point of mineral oil is around minus 19 degrees - 21 degrees. For example, in the cold northern regions of my country, where the temperature is low in winter and the pour point of mineral oil is high, the air compressor cannot be started. The air compressor must be heated before it can be started. If synthetic oil is used, such problems will not occur.

Density: It is the specific gravity. The general oil is about 0.85, except for Sullair's SULLBUE32# and Ingersoll Rand's super coolant, which is about 0.99.

Acid value: New oil will not exceed 0.09. Used oil is used in an air compressor. Impurities, iron filings, and acidic substances will increase the acid value of the oil, which will also accelerate the oxidation of the oil. If the acid value of the oil exceeds 1, it means that the oil is highly polluted, and it is recommended to replace it.

Oil classification

Mineral oil (primary hydrogenation, dewaxing, distillation and other processes are called Class I base oils; the second process is called Class II; the best is the third process is called Class III, which is called semi-synthetic oil in China, but it is still classified in foreign countries. Mineral oil. The real semi-synthetic oil should be a type III base oil with more than 20% of synthetic ester added to it to be called semi-synthetic oil.

Synthetic oil (abbreviated as PAO for poly-α-olefin, abbreviated as POE for ester-based synthetic oil, abbreviated as PAG for ether-based synthetic oil, etc.)

The composition of lubricating oil products: base oil and additives (anti-oxidants, anti-emulsifiers, anti-rust agents, defoamers, viscosity modifiers, dispersants, anti-high temperature esters, etc.) are blended into products.

The role of oil in air compressor

Cooling: The air compressor generates a lot of heat when it is working, and the oil plays a role in heat dissipation.

Lubrication: The oil is equivalent to forming a protective film on the metal surface to reduce wear. The oil film of No. 46 oil is thicker than that of No. 32 oil, which can protect the metal surface especially during cold start.

Sealing: The lubricating oil in the compression cavity of the screw main engine can reduce leakage.

Sound reduction: Reduce the noise when the host is running.