GASPROOF FILTER Russian patent published in 2002 - IPC

FIELD: equipment for purifying air from vapors of hazardous substances. SUBSTANCE: filter has threaded throat, auxiliary insert positioned in throat, and upper net equipped with central spherical projection and secured together with layer of filtering material in cylindrical casing so that layer of filtering material is arranged between auxiliary insert and spherical projection of upper net. Ratio of spherical projection radius and diameter of filter casing is 1:4.15-4.5, and ratio of projection height and filter casing inner diameter is 1:27-36. EFFECT: increased air purifying efficiency and prolonged service life. 7 dwg