An oxygen concentrator is a device that concentrates the oxygen from a gas supply (typically ambient air) by selectively removing nitrogen to supply an oxygen-enriched product gas stream. Two methods in common use are Pressure Swing Adsorption and Membrane gas separation.

Oxygen  concentrators  using  Pressure  Swing  Adsorption (PSA) technology are used widely for oxygen provision in healthcare applications, especially where liquid or pressurized oxygen is too dangerous or inconvenient, such as in homes or in portable clinics. For other purposes there are also concentrators based on Nitrogen Sapration Membrane technology.