Refrigerator oil and working fluid composition for refrigerator
The present invention provides a refrigerating machine oil containing an ester base oil obtained from pentaerythritol and mixed fatty acids of a fatty acid having 8 carbon atoms and a fatty acid having 9 carbon atoms, wherein a ratio of a weight average molecular weight Mw to a number average molecular weight Mn, Mw/Mn, of the ester base oil is 1.06 to 1.20, and used with a mildly flammable hydrofluorocarbon refrigerant.
1. A refrigerating machine oil comprising:
an ester base oil obtained from pentaerythritol and mixed fatty acids of a fatty acid having 8 carbon atoms and a fatty acid having 9 carbon atoms,
wherein a ratio of a weight average molecular weight Mw to a number average molecular weight Mn, Mw/Mn, of the ester base oil is 1.06 to 1.20;
wherein said ester base oil has a flash point of 220° C. or more and a spontaneous ignition point of said ester base oil is 370° C. or more.
2. A working fluid composition for a refrigerating machine comprising the refrigerating machine oil according to claim 1 and a mildly flammable hydrofluorocarbon refrigerant.
3. A method for improving flame retardancy of a refrigerating machine comprising a mildly flammable hydrofluorocarbon refrigerant, the method comprising utilizing a composition comprising, as a refrigerating machine oil, an ester base oil obtained from pentaerythritol and mixed fatty acids of a fatty acid having 8 carbon atoms and a fatty acid having 9 carbon atoms, wherein a ratio of a weight average molecular weight Mw to a number average molecular weight Mn, Mw/Mn, of the ester base oil is 1.06 to 1.20;
wherein said ester base oil has a flash point of 220° C. or more and a spontaneous ignition point of said ester base oil is 370° C. or more.