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Comprehensive Air Compressor Lubricants Knowledge

Time : 2021-09-03 Hits : 219

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 of which 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 oil products
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 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 too long a long time, it will gel or 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 around 0.85, and some brands of super coolant are around 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 If the value is 1, it means that the oil is highly polluted, and it is recommended to replace it.

Oil product 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 air compressor 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.

Air compressor oil service cycle
The service life of air compressor oil is mostly determined by its own base oil category.
The use period set by the air compressor oil manufacturer is generally the standard operating conditions of the air compressor (clean air, operating temperature within 95 degrees, normal operation of the air compressor, etc.). The harsh operating conditions will shorten the life of the oil.
In the after-sales market, you must understand the history of air compressor oil use. If there are problems with the previous oil products or the oil products of non-regular brands are used, please handle them properly. Because inferior oil oxides will remain in the machine, seriously affecting the service life of the new oil.

Common problems with air compressor oil
1. Glue
The base oil of the air compressor oil is not good, and there are many impurities in the gray matter. Such substances are easily oxidized. Through the oxidation reaction of high temperature and air, the sludge like asphalt is formed. Head lock, the general precursor of gelatinization is that the compressed air becomes smelly and the air compressor is running high current.
2. Carbon buildup
Under high temperature operation of the air compressor, especially when the temperature exceeds 95 degrees, the light and heavy components of the oil will separate. After oxidation, it will be adsorbed on the surface of the part like a paint, which will block the oil separator, wear the oil seal of the machine head and leak oil, and the service life of the bearing. shorten.
3. Engine oil emulsification
The air compressor runs at low temperature for a long time, and the water in the machine cannot be evaporated in time, and the oil and water are mixed and emulsified to form a milk-like liquid.
4. The air outlet has a higher oil content
The oil has poor separation of oil and gas, and the base oil contains more hydrides, which makes it difficult to separate from compressed air.
5. The color of the old oil is abnormal
Under normal circumstances, the color of the oil will turn dark red or black, but if it turns to purple or other colors, it means that the oil additives are used improperly. It is recommended to replace the oil in time.