Generally, air is used as the compressed medium, because it has compressible, clear and transparent characteristics, and is convenient to transport (non-condensing), harmless, safe, inexhaustible and so on.
Inert gas is a gas that has no chemical effect on the environment. Standard compressors can compress inert gas as well. Dry nitrogen and carbon dioxide are both inert gases.
Dry air composition: nitrogen (78.08%), oxygen (20.93%), carbon dioxide (0.03%)
