Pressure Swing Adsorption Systems - Air is passed under pressure through vessel containing an adsorbent bed of Carbon Molecular Sieve that adsorb oxygen leaving Nitrogen to go through, part or all of the oxygen will stay in the bed, and the gas coming out of the vessel will be enriched in nitrogen. When the bed reaches the end of its capacity to adsorb nitrogen, it is then regenerated by reducing the pressure, thereby releasing the adsorbed oxygen. It is now ready for another cycle of producing nitrogen.