GB440584A - Improvements relating to air filters particularly for use in connection with gas masks and poison-gas shelters - Google Patents

Abstract

440,584. Air-filters. POELMAN, A., 12, Rue Damalix, Saint-Maurice, Seine, and ETABLISSEMENTS R. SCHNEIDER, 17, Rue Cadet, Paris, both in France. Dec. 1, 1934, No. 34572. Convention date, Dec. 2, 1933. [Class 8 (ii)] [See also Group VI] Air - filters, particularly for use in connection with closed chambers such as dug-outs are characterized by the provision, for arresting poisonous dusts or liquid particles, of an element comprising a preferably endless band of pleated paper, having between the free edges and closing plates thereof, a sealing-composition. As shown, a frame 14 closed at top and bottom by gauzes 16, contains a pleated paper strip 15 secured, as by glue, at its ends to the ends of the frame and sealed along its edges by sealing-composition carried in trays secured to the sides of the frame. Alternatively, a large element may be employed having two or more concentric annular pleated strips, the edges of the strips being sealed by luting in a flanged annulus on one side, and, on the other, in a flanged disc having perforations between the strips communicating with a tubular connection to a physico-chemical filter whereby air is drawn in through the outer, and also through the inner filter ring. The pleating of the strips is preferably carried out between two auxiliary sheets of smaller width which are removed after one edge has been secured in the sealing composition. The paper employed is preferably made from alfa pulp containing 4 or 5 per cent of bisulphite wood pulp and several thicknesses may be employed if desired. Suitable sealing-compositions are stable rubber latex containing a self-vulcanizing agent, polymerized vinyl chloride, or a non- brittle asphalt of melting point about 120‹ C. The pores of the filter may be reduced in size before use by passing therethrough air containing finely divided solids, such as sublimed benzidine sulphate, or atomized solutions in volatile solvents, for example, a solution of synthetic glycerophthalic resin in benzine. The Specification as open to inspection under Sect. 91 also comprises the subject-matter of Specification 440,585. This subject-matter does not appear in the Specification as accepted.