There are three processes for adsorptive generation of oxygen from air using molecular sieve zeolites, namely pressure swing adsorption (PSA), vacuum swing adsorption (VSA) and pressure vacuum swing adsorption (PVSA). Two new variations have recently come onto the market: low-temperature VSA (LT VSA) and two-bed VSA (PVSA). Because of their reliability and long service life, swing adsorption systems have been producing good results for more than ten years, which is why the market share of these systems in the overall oxygen market is constantly rising. Capacity limits with adsorption processes stem at present from the design of the valves and vacuum pumps.
