As the phase-out date for R-123 in developed countries approaches, alternative low pressure refrigerants are being identified and qualified for use in newand existing chiller products. This paper summarizes chemical stability evaluations that were conducted in the laboratory and in operating equipment toevaluate the system chemistry of refrigerant alternatives R-514A and R-1233zd(E).

R-514A is an azeotropic olefin blend comprised of 74.7% cis-1,1,1,4,4,4-hexafluorobut-2-ene (R-1336mzz(Z)) and 25.3% trans-1,2-dichloroethene(R-1130(E)). R-1233zd(E) is the single component olefin refrigerant trans-1-chloro-3,3,3-trifluoropropene. Chemical stability evaluations of therefrigerant, lubricant, and catalysts were conducted in sealed glass tubes according to ASHRAE Standard 97 to confirm acceptable chemical stability ofthe refrigerants relative to R-123. Chemical and physical stability of R-514A was monitored during the performance and endurance testing of twocentrifugal compressor-based chillers. Results of the laboratory and system chemical stability evaluations, and potential system chemistry impacts onreliability and performance, are presented in this paper.

Chemical stabilities of refrigerants R-514A and R-1233zd(E) were proven to be better than R-123, and both refrigerants have been qualified forapplication in a range of centrifugal compressor-based chiller products. R-1233zd(E) has higher operating pressures than R-123 and is applied in newequipment designs. R-514A is a design-compatible replacement for R-123 in both engineered retrofit applications and in new production.