Abstract: A pressurized flow of a refrigerant gas discharged from a gas compressor and which has compressor lubricating oil entrained as a mist therein, is subjected to an oil separation in a separating unit of a separator assembly wherein by impacting flow of the oil-containing gas against impact structure in the separating unit, oil is caused to separate from the gas with the oil falling to the bottom of the separating unit, post-impact flow of the refrigerant gas being in a torturous flow path in the separating unit which torturous flow produces further and additional oil separation from the gas. The gas ultimately, has outlet from the unit at an upper end thereof from whence the gas passes to a point of use, the separated oil passing from the unit through a return capillary tube conduit to the compressor.