Many years ago, refrigeration systems commonly used three basic refrigerants: chlorofluorocarbon (CFC)-502 for low-temperature systems; CFC-12, mainly for medium-temperature systems but sometimes for low-temperature systems; and hydrochlorofluorocarbon (HCFC)-22, mainly for high-temperature systems and sometimes medium-temperature systems.
Today, however, there is a vast selection of refrigerants, and sometimes a technician has a choice in selecting a refrigerant for a particular system. Knowing some of the basic properties of refrigerants can assist a technician in making that selection.