Abstract: The instant invention relates to a method and apparatus for the production of hollow glass fibers using a novel tip design. It is believed that the success of the instant invention is due to the injection of pressurized gas to create a central lumen at distances farther removed from the terminus of the tip than taught possible by the prior art. This results in a more stable process and the production of hollow fibers having more uniform wall concentricity.

Abstract: Porous, silica-rich shapes have improved strength and abrasion resistance by leaching the precursor glass shape in preconditioned acid having silica ion and at least one common ion that is also present in the precursor glass shape. The precursor glass shapes have shapes such as fibers, hollow fibers, tubes, rods, beads, hollow spheres and plates and compositions having 30-75 volume percent silica and at least 10-65 volume percent nonsiliceous acid extractable components. Preconditioning of the acid solution results from a pretreatment of the acid with compounds that dissociate into the ions when added to the acid solution or with shapes, particles or fragments of glass compositions different from or similar to the glass shape to be leached so long as the glass composition has extractable material to provide the silica ion and at least one common ion.

Abstract: A hollow, porous, silica-rich fiber, a process for producing same, and a process for enriching at least one gas from a gaseous mixture utilizing at least one fiber to result in gas separations with good permeability and good selectivity. The fiber is non-crystalline and has pore sizes having a range of 1 to around 50 Angstroms in diameter and a mean pore size of around less than 20 Angstroms in diameter and a filament diameter in the range of 1 to around 250 microns and a wall thickness in the range of around 1 to 50 microns. The fibers with a fine pore structure and thin walls are produced by forming hollow glass fibers hindered or fully phase-separable boron and/or alkali metal glass composition, by attenuation from melt at speeds in the range of 500 ft/min to around 30,000 ft/min. The phase-separable glass fibers are heat treated to yield limited phase-separated hollow glass fibers and these fibers are leached to extract acid and/or water soluble components.