American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc.

Effects of Halogenated Unsaturated Contaminants on the Reliability of HVAC&R Equipment
 N ST-16-008

Annotation

The presence of unsaturated fluorocarbon contaminants in the refrigerantsusedinHVAC&Rsystemsmayresult inreaction products that could potentially cause problems in system performance or reliability. Since 2007, the 40 ppm limit for unsaturated halogenated contaminants in new and reclaimed refrigerants set by the Air-Conditioning, Heating, and Refrigeration Institute (AHRI) in AHRI Standard 700 (AHRI 2015) has proven to be more restrictive to reclaimers, recyclers, and HVAC&R system providers than previously thought. In addition, compounds such as hydrofluoroolefins(HFOs)have been tested as low global warming potential (GWP) alternative refrigerants and shown to have acceptable stability in some applications. So, itmaynot be appropriate to classify all unsaturated compounds as unstable and blanket them under the same restrictive limit.

ASHRAE RP-1641 (Rohatgi and Clark 2015) aims at determining the effects of halogenated unsaturated contaminants present in refrigerants on the stability of refrigerant/ lubricant systems and recommends a concentration limit specific to the unsaturated contaminant below which the refrigerant/lubricant system is thermally stable. Based on a literature search and review, the following refrigerant/lubricant mixtures with their corresponding contaminants were selected for a stability study in sealed-tube tests:

• R-134a (1,1,1,2-Tetrafluoroethane)/Polyolester (POE) with R-1130 (1,1-Dichloroethylene), R-1130(E) (Trans-1,2- Dichloroethylene), R-1131 (1-Chloro-2-fluoroethylene), and R-1234yf (2,3,3,3-Tetrafluoropropene

• R-1234yf/POE with R-1225ye(Z) ((Z)-1,2,3,3,3-Pentafluoropropene), R-1233xf (2-Chloro-3,3,3-trifluoropropene), and R-1243zf (2,3,3-Trifluoropropene)