Abstract: Filtering apparatus includes two or more passages (2) acting in parallel, each having an extended filter (12) which passes through inlet and outlet ports (48, 49), flowable preferably sealed by solidified plugs of the flowable substance such as a polymer being filtered. The flow of such substance to one passage can be terminated so as to permit filter advance under conditions of zero pressure drop, whilst flow through the other passage continues. Filter advance can be assisted by extrusion of a sealing plug in the outlet port under the pressure of such substance from the other passage which is still filtering. In additional or alternative mode, flow into a passage is terminated and a secondary outlet (20, 21) in that passage is opened. This creates a counterflow under the pressure of substance from the other passage, which cleans the filter. The secondary outlet can be sealed by a plug which is extruded during counterflow.

Abstract: Filtering apparatus including two or more passages acting in parallel, each having an extended filter which passes through inlet and outlet ports preferably sealed by substantially solidified plugs of the flowable substance such as polymer being filtered. The flow of such substance through an initially open passage can be terminated so as to permit filter advance under conditions of zero pressure drop whilst flow through the other passage or passages continues. In an additional or alternative mode, flow from a common inlet into a passage is terminated and a secondary outlet conduit in that passage is opened. This creates a counterflow caused by the pressure of substance from the other passage or passages which cleans the filter. Either or any passage or conduit is sealed or valved by a substantially solidified valve plug made of the flowable substance being filtered, said plug being extrudable subsequently when the passage or conduit requires opening to flow.

Abstract: The present invention provides a vascular biomaterial that includes expanded PTFE and a haemocompatible membrane covalently bonded thereto. Also provided is a process for making the vascular biomaterial that involves chemically modifying the surface of expanded PTFE to provide a surface partially covered with for instance, a hydroxyl moiety, and covalently bonding a haemocompatible membrane to the chemically modified surface of expanded PTFE.

Abstract: A process and apparatus for filtering a polymer which passes through a heated, high pressure filtering chamber across which a filter members passes and in which sealing plugs made of the substance being filtered are formed within entry and exit zones thereof. A plug removal zone is provided between the entry port for said filter and the outflow aperture of the filtering chamber. The zone is provided with a valve to permit removal of sealing plug material when in a heat-softened state. A cooled, substantially rigid plug of polymer is formed initially. Thereafter, the plug is heated at one end to soften it and to permit displacement of a part of it through the valve by fresh, hot polymer. In alternative embodiments, the plug removal zone is not needed and the plug is permitted to pass into the passage but is then diverted before meeting the main flow of substance being filtered.