Compressors can suffer burnout. However, when subjected to a detailed analysis, compressor burnout can have many causes. Here are three examples of compressor failure:
Creep
Also known as deformation, creep is a material failure mode that is caused by a combination of thermal and physical stress. If you imagine a metal part that is subjected to bending stresses that are less than its yield strength and heat that is less than its melting point, it would be clear that each condition by itself would not be enough to cause deformation. However, in combination the part would eventually deform, leading to crack formation and failure.
Air compressor parts are simultaneously subjected to physical and thermal stresses. Over time, this will cause failure as the part breaks apart and causes the compressor to seize.
Oil that is clean and structurally sound is effective to reduce the effects of creep. In addition to lubricating compressor parts, oil also removes heat from compressor parts. Compressor oil analysis can identify the properties of the oil to ensure that it has not broken down and is still able to carry heat. Without thermal stress, the weak physical stress cannot cause failure by itself.
Wear and Abrasion
Wear is a material failure mode that occurs when two parts rub against each other and physically remove material from the interfacing parts. Abrasion is a material failure mode that occurs when two parts rub against each other with particles between them with the particles scraping material from the interfacing parts. Because compressors utilize cyclical motion, they are subject to wear and abrasion.
The primary purpose of oil is to lubricate parts to prevent wear. With a slick material, such as oil, between parts that rub against each other, the interface is less likely to wear. However, a key to lubrication is to use a lubricant viscous enough to stick to the parts. When lubricant breaks down and is lost, it cannot stick to the interfacing parts and prevent wear. This is so well-known that destruction of compressors by lubricant loss will often void a compressor warranty.
In addition to providing a slick interface, lubricants also wash away particles. However, if these particles remain in the lubricant, they can be recirculated through the compressor. A compressor oil purifier can remove fine solids from the oil so that they cannot recirculate into the compressor. In this manner, a compressor oil purifier can reduce the risk of abrasion degrading the integrity of compressor parts.
Corrosion
Everyone has seen examples of corrosion. A rusty nail or green penny has been corroded. Chemically speaking, corrosion occurs when a cathode takes up electrons from an anode via an electrolyte. As a result, the anode is reduced to a different chemical compound. For example, iron is reduced to iron oxide, also known as rust, in the presence of water, an electrolyte that contains extra oxygen ions.
Oil is usually a good medium for resisting corrosion. Oil is not an electrolyte and repels water, a common electrolyte. However, compressors and other machines that use oil as a lubricant can still be corroded. First, water can become mixed with water. The water and water vapor in the oil can act as an electrolyte that causes corrosion of compressor parts.
Second, oil can become oxidized if water mixes with the oil and the water breaks down inside the compressor. The extra oxygen ions in oil can cause corrosion, just as extra oxygen ions in water cause corrosion.
Third, oil can acidify as it breaks down. For example, new oils often have a pH level of around 8.0 and oxidized oil has a pH of about 5.0. Remember that anything with a pH less than 7.0 is an acid. Acids, by definition, include hydrogen ions, which makes them excellent electrolytes. These hydrogen ions cause corrosion since they create a pathway for electron exchange leading to corrosion.
Compressor oil purifiers can reduce the risk of corrosion by removing acids from oil. Oil separators can reduce the risk of corrosion by removing water from oil. Thus, a combination of compressor oil purifiers and oil separators can stop all three pathways for corrosion of compressor parts.
Corrosion, creep, wear, and abrasion can destroy compressors. Oil is the most effective preventative measure against all of those failure modes.
