Spacer liquid / gas centrifugal compressor unit and acquires such a spacer

This liquid / gas separator for centrifugal compressor motor comprises a housing (8) internally provided with at least one stage (10, 11) gas separator adapted to separate a gas phase from a liquid phase admitted housing inlet. The housing (8) internally comprises a housing (13) wherein the separated gas phase flows by said buffer stage (10, 11) and in which is mounting a compressor stage (4) of the motor-compressor (1).