Untreated compressed air always contains contaminants because of the nature of the gas and how it is produced. The need for air treatment basically results from 3 characteristics of compressed air.
Dry air is mainly composed of nitrogen (78%) and oxygen (21%). Air will keep the same nitrogen/oxygen ratio after compression, so additional treatment is needed to change this gas mix.
Nitrogen gas is essential in the preservation of snack foods, bottling, packaging, electronics soldering and a number of other applications. It is also crucial during laser cutting and accounts for 60% of the total operational cost of a laser cutting machine used for different type of metals.