Ultracentrifuge for separating fluid mixtures

A centrifuge for the separation of fluid mixtures having light and heavy fractions consists of: a cylindrical rotor; disc type end-plugs closing the ends of the rotor; means for mounting the rotor for rotation about its cylindrical axis; a housing member enclosing the rotor; a vacuum chamber in the housing about the central portion of the rotor; a collection chamber at each end of the housing, the innermost side of which is substantially formed by the outer face of the end-plug; means for preventing flow of the fluid from the collection chambers to the vacuum chamber, at least one of said end-plugs having holes communicating between the collection chamber and the inside of the rotor to induce countercurrent flow of the fluid in the centrifuge; means for feeding fluid to be processed into the centrifuge; means communicating with the collection chambers to extract the light and heavy separated fractions of the fluid; and means for rotating the rotor