Working of a typical PSA Device can be described by taking the example of oxygen separation from air. Air separation starts at the PSA process when air from the atmosphere is compressed at a pressure of 100 psig. The compressed air is then directed to one of the two adsorbing tanks by valves. In the tank the Carbon Molecular sieve desorbs the oxygen selectively while letting go Nitrogen and Argon. Impurities like Carbon dioxide or water also gets adsorbed by the sieve at the beginning of the bed. As the adsorber starts producing the Nitrogen or Argon composition, a sensor opens the valve which lets the release of stream as a product.

Gradually the adsorbent becomes saturated with oxygen and is no longer in a position to adsorb further oxygen from air. Here at this point, the product stream from the adsorber is cut off. A Bleed stream from the adsorber is opened and the pressure in the tank is released. This reduced pressure makes the dedsorbed oxygen to be released through the vent. Two adsorbers work simultaneously in a PSA unit. While the one is de- adsorbing the oxygen, on the other air is fed for adsorption. This cycle of adsorption and de-adsorption results in a continuous stream of production.