Abstract: Tank for a motorized compressor, more particularly for an installation for he isotopic separation by gaseous diffusion, which has a generally cylindrical shape and a vertical axis containing a motorized compressor with an axial intake for a low pressure gas flow, a lateral intake for a medium pressure flow to be mixed in the motorized compressor with the low pressure flow and a diffuser for forcing back the high pressure flow at the outlet from said motorized compressor, whereby said tank has a first lateral opening for the entry of the medium pressure flow and a second lateral opening for the discharge of the high pressure flow, wherein for ensuring separation of the medium pressure flow before entering the motorized compressor and the high pressure flow at the outlet from said motorized compressor, it comprises a truncated cone-shaped skirt whose large base is inclined relative to the tank axis, said skirt being fixed to the tank along a continuous line passing on the one hand below the first opening for th