Air valve

An air valve for a sewerage system which comprises a concave, downwardly facing cover that is carried by a pipe connector connected generally coaxially thereto, an upper end-part of the pipe connector surrounded by a wall of the cover, a ring-shaped, upwardly facing first seat ridge carried by and sealingly connected to the cover wall, a second ring-shaped seat ridge generally coaxial with the cover wall and carried by and sealingly connected to said pipe connector upper end-part, a valve plate vertically movable in the cover, and an annular rubber-elastic valve washer carried on the valve plate, said valve washer having a roughened lower surface, the roughened lower surface having, in first and second annular regions that co-act with said first and said second seat ridges, respectively, a degree of roughness less than a degree of roughness established in a third annular region located between said first and said second annular regions.

A valve disk for use in an air valve for a sewerage system, the air valve having a concave, downwardly facing cover that is carried by a pipe connector connected generally coaxially thereto, wherein an upper end of the pipe connector is surrounded by a wall of the cover, a ring-shaped, upwardly facing first seat ridge which is carried by and sealingly connected to the cover wall, a second ring-shaped seat ridge which is generally coaxial with the cover wall and is carried by and sealingly connected to the upper end of the pipe connector, and a valve plate which is vertically movable in the cover, said valve disk comprising:

• an annular, rubber-elastic valve washer carried on the valve plate, said washer having a roughened upper surface and a roughened lower surface, the roughened lower surface acting in conjunction with moisture inherent in the sewerage system to form a seal with the first and the second seat ridges so as to bridge a ring-shaped air through-gap between the seat ridges.