The MMB 305 is a solids-retaining centrifuge for removing water and solid particles from mineral oils, such as diesel fuels, lubrication running-in, hydraulic, cutting and quench oils. The machine needs to be stopped at intervals for manual removal of the solids. The bowl is mounted on a vertical spindle driven by a vertically mounted motor, via a flat belt transmission unit. The system may require other ancillary equipment. The robust design has the benefits of easy installation, operation and maintenance. The flexible bowl may be used either as purifier or clarifier. The MMB 305 has a capacity of 26 gpm and includes a set of tools, an intermediate service kit, a test report, a certificate of origin and a service manual. The unit comes with 12 months warranty from start-up or eighteen (18) months from delivery, whichever occurs first.