R-466A, R-13I1, Trifluoroiodomethane, chemical stability, reliability
Recently a new blend, R-466A, utilizes R-13I1 (trifluoroiodomethane, CF3I) in a blend with R-32 and R-125 that ASHRAE Standard 34 classified as A1 (lower toxicity and nonflammable) which is the same safety classification as R-410A. R-466A has been shown to have similar performance and capacity to R-410A, but with only 1/3 of the GWP as compared to R-410A. R-13I1 is not a new molecule. It was considered in the CFC (chlorofluorocarbon)/HCFC (hydrochlorofluorocarbon) to HFC (hydrofluorocarbon) transition period, but was abandoned because of chemical stability concerns. The iodine atom in the molecule drives the instability concerns. Halogenated refrigerant chemical stability generally follows the rule that fluoride substitutions are more stable than chlorine than bromine and finally iodine. HFCs that later replaced the CFCs and HCFCs were generally found to be more chemically stable with materials. In this paper, the authors will summarize highly accelerated life test results (HALT), ASHRAE 97 sealed glass tube methodology, for R13I1 and materials compatibility of select elastomers and polymers. Also provided are the chemical stability of R-466A results of accelerated life test equipment (ALT) testing using optimized materials and additives that show R-466A is a viable option for use.