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How to distinguish compressor oil viscosity selection

When the compressor internal and external lubrication systems are used together, the viscosity of the oil used in the internal lubrication system should be mainly considered, and the external lubrication system should be considered separately. At this time, the external lubrication system can generally choose ISO VG68 or No. 100 oil. The internal lubrication system should be calculated according to the typical viscosity calculation formula, and then verified by the actual bench.


Low-pressure air-cooled air compressors, such as 3W—0.9/7 or 2V—0.4/12, often use ISO VG68 or No. 100 oil, but water-cooled air compressors can use ISO VG68 oil.


When the exhaust pressure is higher than 20MPa, ISO VG100 oil can be used, and ISO VG150 oil can be used at higher pressures.


Generally, ISO VG68 or No. 100 oil can be selected for the crankcase lubrication system of high pressure compressor with crosshead.


If the viscosity is not the same in winter and summer, the oil viscosity in summer is greater than that in winter.


The viscosity of the oil in the oil cavity of the diaphragm compressor should be selected according to the type of the oil pump. Generally, ISO VG32 or 46 can be selected.

When compressing natural gas, petroleum gas and other hydrocarbon gas, the viscosity of the oil should be diluted by the hydrocarbon, so the viscosity of the oil selected is greater than that of the air compressor oil.

Oil-injected internal cooling rotary air compressor:


Generally, ISO VG32 oil can be used for oil-injected rotary air compressors. However, at present, oil-injected sliding vane air compressors at home and abroad generally choose oil with higher viscosity, such as ISO VG68 or ISO VG100 oil. Compressors equipped with metal fins are more viscous than those equipped with plastic sliding fins. Single-stage compressors have higher oil viscosity than multi-stage compressors. However, the viscosity of the oil used in the oil-injected rotary compressor should not be greater than ISO VG100.

Speed compressor:


Mainly consider the factors of bearings, speed-increasing gears and oil seals. Generally, ISO VG32 or ISO VG46 oil can be selected. If it is driven by an electric motor, the main shaft oil pump is directly driven by the main gear. At this time, ISO VG68 oil can be used. If it is driven by a steam turbine, the main shaft oil pump is driven by the extension of the steam turbine, and there is no gear box. At this time, ISO VG32 or ISO VG46 oil can be used. Rolling bearings use lithium-based grease and complex calcium-based grease with a penetration of 265-340.

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