Lubricants for HFCs

In the early 1990s, polyalkylene glycol (PAG) was chosen by most OEMs over POE lubricants for automotive air conditioners having an R134A haloalkane system. This was over concern of moisture contamination in the rubber hoses used to connect the system components. Ester hydrolysis is therefore of fundamental importance to manufacturers. PAG also proved to be a better lubricant than POE, especially when aluminum components were used.

Because of its relatively low electric resistivity, however, PAG could not be used in the hermetic compressors used in domestic refrigerators. Nevertheless, because domestic refrigerators are closed systems, it is feasible to use POE lubricants if strict moisture and contaminant control is implemented on the production line.

Thanks to their positive experience with POE lubricants, most OEMs started to re-evaluate the use of POEs in air conditioners. During this process, the hydrolytic properties of POEs became of great concern because of the unavoidable air and moisture contamination that takes place during air conditioner installation and repair. Therefore PVE, which has the same ether group as PAG, has become an attractive, practical alternative to POE.

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