Abstract: A filter unit comprises a housing through a wall of which is formed an aperture, an annular insert of a plastics material located in said aperture to make sealing contact with the defining walls of the aperture, a closure member removably mounted in, to make sealing engagement with, the annular insert, and a filter cartridge mounted on the closure member to extend into the housing, the closure member and filter cartridge being locatable on and removable from the housing as a unit.

Abstract: Detectable vapors, odors and smells are removed from a stream of compressed air entering a tubular cartridge and passing axially through a cylindrical bonded granular or supported granular sorbent bed or radially through a bonded granular or supported granular tubular sorbent bed arranged so that the air velocity therethrough is not greater than 300 ft/min and the minimum contact time with the granules is 0.1 seconds, the bed being arranged to be traversed by the entire volume of air passing through the cartridge. The air then passes through a surrounding microporous or pleated filter element prior to being discharged radially from the cartridge.

Abstract: A self-supporting tubular fibrous filter element consists of elongated fibers compacted in a direction parallel to the central axis of said tubular element to have a substantially constant density throughout the length and thickness of the tube with a majority of the fibers in parallel to one another in a circumferential direction about the said axis. When required, a perforated cylindrical support sheet is molded into at least one cylindrical face of the element.

Abstract: Tubular filter elements are formed by first feeding a slurry into a tubular moulding space between a vertical core and a cylindrical fine mesh screen. Air pressure is applied to the slurry so that the liquid drains through the screen and through a screen at one base of the space, while a mass of microfibres builds up to be removed from the space for bonding by a synthetic resin. A reciprocable sleeve increases the effective height of the screen as the mass builds up. Layers of microfibres having different qualities can be assembled by using different core diameters in succession. Filter elements that need not necessarily be cylindrical can be formed by this or analogous pressure methods in which the majority of the microfibres are directed approximately parallel to one another, and/or in which one or each face of the filter element has moulded into it a perforated sheet of supporting material.

Abstract: Tubular filter elements are formed by first feeding a slurry into a tubular moulding space between a vertical core and a cylindrical fine mesh screen. Air pressure is applied to the slurry so that the liquid drains through the screen and through a screen at one base of the space, while a mass of microfibres builds up to be removed from the space for bonding by a synthetic resin. A reciprocable sleeve increases the effective height of the screen as the mass builds up. Layers of microfibres having different qualities can be assembled by using different core diameters in succession. Filter elements that need not necessarily be cylindrical can be formed by this or analogous pressure methods in which the majority of the microfibres are directed approximately parallel to one another, and/or in which one or each face of the filter element has moulded into it a perforated sheet of supporting material.