Centrifuges, centrifuge installations and arrangements for controlling the flow within them

This invention relates to valve arrangements and to centrifuges incorporating such valve arrangements. In a plant where isotopes of an element in a gaseous form are separated, for example where uranium 235 is separated from uranium 238, both isotopes being in the form of uranium hexafluoride, it is important that the effect of impurity gas within the plant is minimised. This is so because otherwise the plant may have to handle gases of a molecular weight which it was not designed to handle and this can have deleterious effects upon the operation of the plant and may cause breakdown of some centrifuges. An object of the present invention is to provide a valve arrangement and a centrifuge enrichment plant utilising such valve arrangements so that such deleterious effects tend to be avoided. The valve arrangement comprises a conduit containing a ball valve which is responsive to gas flowing in the conduit, the ball valve being obstructive to flow in one direction in the conduit when abnormal gas flow occurs in the conduit. Preferably, the ball valve comprises a mesh arrangement for supporting a ball, said mesh arrangement being permeable to gas. Advantageously, the ball valve comprises a rest for the ball, which rest supports the ball in such a manner as to block gas flow. In use, the ball may rest upon said mesh when the valve is open and may rest upon said rest when the valve is shut. (Auth.)