| 摘要 |
1,192,661. Gas filter. NORTH AMERICAN ROCKWELL CORP. 16 Jan., 1968 [27 Feb., 1967], No. 2262/68. Heading B1T. A plurality of filter socks 18 have their open ends permanently moulded into a plastics frame 17, of grid construction defining an opening 19 for each sock (Fig. 4, not shown), frame 17 being secured to a peripheral frame 12 of channel section metal in the same moulding operation. Socks 18 are of two-ply material, resin-bonded glass fibre inside and serum or buckram outside. They are made from pieces of material, folded over and stitched, glued or heat-sealed up one side and along the bottom end (Figs. 6, 7, 9, 10, not shown). The open ends of socks are turned in and stitched (Fig. 8, not shown) to form beads 29. Frame 12 may be coated with bonding medium before the moulding step, or may be provided with holes to assist bonding to the plastics, which may be polyvinyl chloride. A number of filters as illustrated may be stacked together and enclosed by a peripheral strap (Figs. 1, 2, not shown), for installation in parallel in the air duct of air-conditioning or ventilating plant, the socks extending downstream from the frame 17 so as to be straightened out and expanded in use. Socks 18 fold flat on to frame 17 for storage and transport. Frame 17 may be reinforced by metal bars 33 which are joined to frame 12. The front face of frame 17 is sufficiently elastic to act as its own sealing gasket, when the filter is placed in a surrounding frame. Frame 17 may be coloured according to a code denoting filtering efficiency.
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