| 摘要 |
Dust half-mask, containing nose, chin and cheek sections with an internal first belt of sponge on the edge adhering to the chin, cheeks and the nose and an external plastic metal strip in the nose part and an external elastic overhead and neck strip, fixed separably in the side parts of the edge, containing an exhalation valve located in the convex part, characterized in that its bowl (7) consists of a highly porous preliminary filter, created from layers of polypropylene fibres, connected by stitches on the edge and at least one layer of fine filter, which is a mixture of evenly spaced fibres of at least two materials with different dielectric constants, where the maximum porosity of the filtering structure is less than 30 percent, and further the bowl (7) has, in its nose part (A), an arched ridge (8) created from the ends of the flap of the created cone, connected and pressed by their internal surfaces, which cone has a circular base with length of side equal to the length of the chord (D) of the arch of the ridge (8), and under the ridge (8), on the conical surface, it has a hole for the exhalation valve (9), and in the cheek part, it has allowances for the holders (3, 3') of the overhead and neck strip (5, 5'), and also, on the internal rim of the edge of the nose part (A), a second belt of sponge (10) is attached.<IMAGE>
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