Abstract: The filter membrane comprises a porous structure made of a material selected from sintered ceramics, sintered metals, microporous carbon, and microporous glass, and is characterized by the fact that its entire external surface, including the inside surface of the pores in the structure, is covered with a thin and continuous film of carbon or of an oxide. In a sintered aluminum membrane, the surfaces of pores are coated with a dense and continuous thin layer of zirconia which prevents the surfaces from being degraded in service. In the figure, curve 3 shows how the throughput of a membrane without a zirconia layer falls off over time, while curve 4 shows little change in the same membrane having such a layer.

Abstract: Rotating membrane tangential filtration apparatus with low power consumption is characterized by a direct drive system (10) along the axis of its membrane (5), a sealing system (11, 16) between the residue and filtrate compartments, which system used frictional ceramic parts; the diameter of the filter membrane is small relative to its length, and the filter layer is arranged on its outside surface; it is provided with a system for taking up the slack caused by differential expansion.

Abstract: In a method and device for filtering a suspension of particles in a liquid the liquid is passed continuously through a porous membrane, particles from the suspenion gradually accumulating on the membrane and clogging its pores. The filtered liquid is caused to flow momentarily in the reverse direction to return the accumulated particles to the suspension and so unclog the membrane. To achieve this the filtered liquid is fed into one end of a conduit wound around an axis and recovered from its other end, and the conduit is rotated about its axis, the speed of rotation gradually increasing, and then suddenly stopped.

Abstract: A device for abstracting the liquid phase from a suspension comprises a microporous membrane (23) applied on the outside of a microporous body (22) to which a flat capillary duct (11, 18) is fixed. Means (9) are provided to rotate the duct about a vertical axis, with the membrane being immersed in the suspension in such a manner as to provide tangential filtering of the suspension and to cause the liquid phase filling the duct after passing through the membrane and the porous body to be ejected centrifugally and received by a receptacle (5) provided for the purpose.

Abstract: First and second identical filters (6, 20) are connected in series. A backpressure unit (30) for intermittent backwashing is connected to the outlet from the second filter. Means are provided for measuring or setting the pressure P.sub.1 at the inlet to the first filter, the backpressure P.sub.2, the pressure P.sub.3 of the liquid between the two filters and the pressure P.sub.4 at the outlet from the second filter. Means (34) determine A=P.sub.1 -2P.sub.3 +P.sub.4, and B=(K/2N)(P.sub.2 -2P.sub.1 +P.sub.4), where K and N are constant coefficients, and a circuit (35) causes the backpressure unit to apply backpressure for backwashing when A=B. This amounts to comparing conditions in the first and second filters and triggering backwashing only when required, thereby avoiding wasting time with too frequent backwash operations, or conversely with dismantling and regenerating the filters due to too infrequent backwashing leading to clogging that cannot be cleaned by backwashing.

Abstract: Low density polyethylene with a very small proportion of low molecular weight polyethylene (e.g. such as can be extracted by washing by ethanol) is used as an insulation material for high voltage power cable.