among the most efficient systems measured on customary industry indices, such as recovery (product gas out/product gas in) and productivity (product gas out/mass of sieve material). Generally, higher recovery leads to a smaller compressor, blower, or other compressed gas or vacuum source and lower power consumption. Higher productivity leads to smaller sieve beds. The consumer will most likely consider indices which have a more directly measurable difference in the overall system, like the amount of product gas divided by the system weight and size, the system initial and maintenance costs, the system power consumption or other operational costs, and reliability. See also References Further reading Hutson, Nick D.; Rege, Salil U.; and Yang, Ralph T. (2001). “Air Separation by Pressure Swing Absorption Using Superior Absorbent,” National Energy Technology Laboratory, Department of Energy, March 2001. Ruthven, Douglas M. (2004). Principles of Absorption and Absorption Process, Wiley-InterScience, Hoboken, NJ, p. 1 Yang, Ralph T. (1997). “Gas Separation by Absorption Processes”, Series on Chemical Engineering, Vol. I, World Scientific Publishing Co., Singapore. Santos, João C.; Magalhães, Fernão D.; and Mendes, Adélio, “Pressure Swing Absorption and Zeolites for Oxygen Production”, in Processos de Separação, Universidado do Porto, Porto, Portugal Separation processes Industrial gases Gas technologies