Valve assembly for a replaceable filter respirator

Claim 1

In a half mask of the type including: a face piece, a valve assembly rigidly affixed to said face piece and providing an exhalation valve having an inlet and an outlet defining a cylindrical valve seat for an exhalation valve, and, an inhalation valve having an inlet and an outlet defining an annular valve seat for an inhalation valve arranged concentrically with and radially outwardly of said exhalation valve; valve members cooperating with said respective valve seats; and, filter element means in communication with said annular valve seat: the improvement comprising: said face piece being formed from a resilient and compliant material; a substantially rigid imperforate wall member integral with and completely surrounding said annular valve seat and extending radially outwardly thereof; said imperforate wall member terminating at its outer periphery in a continuous peripheral flange extending forwardly of said wall member and then outwardly thereof to define a shallow recess at the front of said wall member; ribs on said wall member extending forwardly thereof and in directions generally radially of said valve assembly, said ribs defining channels on the front face of said wall member which communicate with said inlet of said annular inhalation valve seat; a layer of filter material co-extensive with said imperforate wall member and overlying said ribs; a perforate frame member co-extensive with said wall member and overlying said filter material, said frame member having a central opening and a cylindrical extension surrounding said opening for spigotal cooperation with said cylindrical valve seat of said exhalation valve; latch means integral with said frame member and for latching cooperation with the outwardly extending portion of said wall flange; and, harness attachment means on a rearmost face of said wall for attaching said half mask to the head of a user; said wall, said filter element and said frame extending laterally toward both sides of said face piece in dihedral formation and presenting a maximized filtering surface area of said filter.