Patent ID: 7493900

Claim:
A filtering face mask that comprises: (a) a mask body that is adapted to fit over the nose and mouth of a wearer; and (b) an exhalation valve that is attached to the mask body, the exhalation valve comprising: (1) a valve seat that comprises: (i) a seal surface; (ii) an orifice that is surrounded by the seal surface; and (iii) a flap-retaining surface; and (2) a single flexible flap that has a stationary portion and only one free portion and a peripheral edge that includes a stationary segment and a free segment, the stationary segment of the peripheral edge being associated with the stationary portion of the flap so as to remain at rest during an exhalation, and the free segment being associated with the one free portion of the flexible flap so as to be lifted away from the seal surface during an exhalation, the free segment also being completely located below the stationary segment when the filtering face mask is worn on a person and viewed from the front; and (3) a valve cover that is disposed over the valve seat and that comprises a surface that holds the flexible flap in an abutting relationship against the flap-retaining surface, wherein the flexible flap is held against the flap-retaining surface in a location and position relative to the seal surface such that the flap is pressed towards the seal surface in a substantial abutting relationship therewith under any orientation of the valve when a fluid is not passing through the orifice.