Apparatus for casting tubular, polymeric membranes for reverse osmosis and ultrafiltration

Claim 1

In an apparatus for casting tubular, polymeric membranes for reverse osmosis and ultrafiltration, comprising: (a) a plurality of upwardly extending casting tubes, (b) a casting bob assembly for insertion in the lower end of the bore of each of the casting tubes, (c) mounting means for mounting each casting tube, with the casting bob assembly in the lower end thereof, for relative movement therebetween, whereby the casting bob assembly may be displaced along the bore of each casting tube when placed therein, (d) means for supplying a casting solution to the casting bob assembly, (e) means for supplying a gas to the bore of each casting tube, below the casting bob assembly, when the casting bob assembly is inserted therein, (f) means for feeding a gelation liquid to the bore at the lower end of each casting tube when the casting bob assembly is inserted therein, and wherein: (g) the casting bob assembly comprises: (i) a centering sleeve, slidably along the bore of each casting tube, and having an open ended, upwardly extending bore, at least a portion of which is screw threaded, and a lower cylindrical extension inwardly spaced from each casting tube when placed therein, (ii) a casting bob having an upper portion which has a downwardly extending casting solution passage therethrough and which is screw threaded externally with the screw thread screwed into the screw threaded portion of the centering sleeve, an intermediate portion which is integral with the upper portion and protrudes from a lower end of the bore of the centering sleeve and defines an annular, casting solution outlet with the centering sleeve, the intermediate portion having casting solution passage means for distributing around the annular casting solution outlet, casting solution from the downwardly extending passage, and a lower cylindrical portion integral with the intermediate portion and beneath the cylindrical extension and defining an annular, casting solution outlet gap therewith which is adjustable by screwing the upper portion into the centering sleeve, the lower portion being spaced from casting tube when placed therein to define an annular casting space therewith, the improvement comprising: (h) the casting bob assembly includes: (i) a transport sleeve slidable upwardly as a press fit around the lower portion of the casting bob to seal against and around the lower, cylindrical extension and seal the annular, casting solution outlet gap while the casting bob assembly is being transported from one casting tube to another, the transport sleeve being slidable along the bore of each casting tube when inserted therein; and (ii) securing means for releasably securing the transport sleeve in the lower end of each casting tube and sealing the lower end of each casting tube to the mounting means.