Oxygen (O2) constitutes approximately 21% of the air, has a gaseous specific gravity of 1.1 and has a boiling point of -297.3°F (-183°C).
Oxygen is produced by air separation processes that use either cryogenic liquefaction and distillation or vacuum swing adsorption (VSA) separation. Oxygen can be stored and shipped as either a gas or a cryogenic liquid.
The principal uses of oxygen stem from its strong oxidizing and life-sustaining properties. It is used in medicine for therapeutic purposes and in the metals industry for steelmaking and metal-cutting applications. In the chemical and petroleum industries, oxygen is used in the production of a wide variety of fuels and chemicals. Oxygen is used in the pulp and paper industry for a variety of applications, including pulp bleaching, black liquor oxidation and lime kiln enrichment. In the glass industry, oxygen/fuel combustion is used to reduce particulate and NOx emissions in melting operations.