\"One-way valve, and a respirator\".A one-way valve (20), in which the valve comprises a valve body which includes a frame (50).A valve opening through the frame (52) and a valve seat (54) which extends from the frame and that involves at least partially opening the valve.The valve includes a flapper valve (70) which has a first part (76) attached to the frame and a second adjacent part (37) free to move from a first position.The second part is in contact with at least a portion of the valve seat (54), to a second position, where at least part of second part is spaced from the valve seat (54).When the flapper valve (70) has a thickness not uniform.Variations of the thickness may occur between sides of the flapper valve (70), and may also occur between the ends of the flapper valve (70).
