Since its initial recognition in 1928 and commercialization in 1936, R-22 hasbeen applied in systems ranging from the smallest window air conditionersto the largest chillers and heat pumps, including those for district coolingand heating. Individual equipment using this versatile refrigerant ranges from 2 kW to 33 MW (0.5to 9,500 tons) in cooling capacity. R-22 use includes equipment with rotary-rolling-piston, reciprocating-piston, scroll, screw, and centrifugal compressors and, experimentally, absorption cycles.No other refrigerant has achieved such a wide range of commercial capacities or applications.