GB222366A - Improvements in or relating to gas masks - Google Patents

Abstract

222,366. Davis, R. W.G. Jan. 18, 1924. Respirators.-In a gas mask of the type comprising an inner ori-nasal mask and an outer facial mask, the exhaled air is discharged directly from the inner mask to the exterior, and the inspired air is drawn into the space between the masks in such a way as to impinge upon, or flow adjacent to, the eye-pieces; by this arrangement the clouding of the eye-pieces is prevented. As shown in Fig. 1, air exhaled from the inner mask a passes directly to the exterior by way of a tube m and non-return valve l. The inspired air is drawn through a tube j and orifices n into the space h between the inner mask a and the outer mask b, and is then drawn through the orifices k<1> into the interior of the inner mask. The orifices k<1> may be partly covered by shields o, as shown in Fig. 3, to force the incoming air to flow in the desired direction. In a modified construction, the incoming air is made to impinge on the eye-pieces by tubes leading from the orifices n, and the orifices k<1> are provided with non-return valves.