Improvements in or relating to air-purifying devices, particularly air-purifying canisters for use in respirators

摘要

482,768. Air-filters; respiratory appliances. MINE SAFETY APPLIANCES CO. Dec. 19, 1936, No. 34949. Convention date. Dec. 19. 1935. [Class 81 (ii)] [Also in Group XXVIII] An air-purifying device, particularly for respirators, comprises a body member through which filtered air is passed, and a sheet of filter material surrounding said member, the sheet being formed with a plurality of folds which overlap each other and lie close to the body member. As shown, a casing 1, strengthened by corrugations 6, is closed by end caps 3 and formed with an inlet port 4. Each cap is formed with a shoulder 7 and flange 7a which hold in position a tubular member 9 of perforated metal, woven wire, &c. and a perforated tube 11. Material 12 for removing toxic gas is disposed between member 9 and tube 11 and is prevented from being drawn into tube 11 by a cloth 16 wrapped around it. A flexible hose 13 connected to the face piece is attached to one or both unperforated ends of the tube 11. In the first case, one end of the tube 11 is sealed as shown. The filter sheet 17 surrounding the member 9 is formed with a series of overlapping folds 18, and is held in position at each end by two plates 21, 26, Fig. 2, formed with interengaging fingers 24 between which the filter sheet is gripped. The projecting ends of the filter sheet are gathered around the shoulders 7, and attached thereto by adhesive: The plates 26, 21 are held in position by detents 27, and by detents 22 and angle pieces 23 respectively. If desired, the filter folds may be supported by forming member 9 with overlapping folds to take the place of the plates 21. The filter sheet preferably consists of a cellulose fibre sheet impregnated with finely divided substances. For example, methane, ethane, ethylene, acetylene, &c., or vaporized liquids such as kerosene or gasoline are ignited, and the supply of air to the burner reduced so that finely divided carbon is produced, the smoke being passed through the cellulosic material. Other smokes, such as that produced by the reaction of two gases, e.g., hydrogen chloride and ammonia, or by dilution of zinc vapour accompanied by its oxidation, may be used. Two layers of treated material may be superimposed. Reference is made to pore openings of less than 1 micron in size.