What Causes Oil Contamination ?

Air compressor oil is more than simply a lubricant.  It also serves to dissipate heat and to flush away dust and  metal particles that are detrimental to bearings and gears.  Contaminants in the oil though can greatly affect the life of the lubricant. 

External Contaminating Factors

One of the greatest contributors to to the degradation of the oil is oxygen, which is introduced into the compression chamber, and is by its very nature an oil contaminant.  The oil additives must be able to handle the oxidation inherent in a piece of equipment designed to create air from an air-oil mixture.  Along with ambient air, water vapor is drawn into the compressor in the form of humidity, which also acts as a contaminant.  In addition, dust is drawn into the unit, which in small quantities will bypass the inlet filter and contaminate the lubricant.  Air, water and dust are all very normal contaminating products that have adverse effects on overall oil life.

Compressor oil also is affected by unique or extreme environmental conditions.  These include industrial pollution that can be chemical reactants in the oil, as well as chemical vapors.  The life of the compressor is dependent on the oil, and the oil is dependent on its environment. 

Internal Contaminating Factors

Air compressor oil is also affected in many ways by entrained products, which act as catalysts and reactants to break down the oil.  Rust and wear metals from the internal components of the compressor are common oil contaminants, that can greatly reduce lubricant life.  Acids formed from gas vapors drawn into the unit are another contaminant with which the oil additive packages have to contend.  Additionally varnish and sludge can form from chemical reactions in the oil, which can greatly reduce the life of the oil, and the heat transfer abilities of the compressor itself.

As all of these types of contaminants are introduced or formed in the oil, the life of the oil is reduced.  This is the reason that oil analysis is the key to maintaining your compressed air system.