A general method for separating gases by cyclic adsorption and desorption from a selective adsorbent, at alternating pressures. Invented by C. W. Skarstrom at the Esso Research and Engineering Company in 1958 and subsequently engineered by the Union Carbide Corporation. The Société de L'Air Liquide, France, made a similar development at that time. For separating nitrogen from air, carbon molecular sieve is the preferred adsorbent. For separating oxygen from air, a zeolite is used. Other zeolites have been used for other separations. Many variations on this basic process have been developed for specific gas mixtures and are known by special names; those described in this dictionary are: AUTO-PUREX G, Bergbau-Forschung, COPISA, COPSA, DWN, DWO, Generon, HYSEC, KURASEP, LO-FIN, MOLPSA-nitrogen, Moltox, MRH, NitroGEN, OxyGEN, Oxy-Rich, OXYWELL, Polybed, PSPP, Remet, RPSA, Sumitomo-BF. See also: TSA