AZEOTROPE: a mixture of two or more refrigerants in which the liquid and vapor have same composition at equilibrium. In addition, the resulting pressure of the mixture is either higher or lower than the pressure of any of the components. Azeotropes behave like pure component refrigerants because there is no change in boiling temperature or shift in composition during phase change, equipment operation, or leakage.

Developed for use in low temperature refrigeration (the evaporator pressure stays out of vacuum down to -40F). R-502 offers lower discharge temperature and improved capacity compared to R-22. Commercial refrigeration systems can perform low temperature refrigeration in a single stage with relatively inexpensive compressors.