Valve

Claim 1

A butterfly type valve comprising valve casing means having a flowway therethrough, valve seating means disposed within said valve casing means in substantially surrounding relation to said flowway, and valve closure means rotatably mounted within said valve casing means for movement between open and closed positions of said flowway, said valve closure means having a central body portion, the axis of rotation, of said closure means passing through said central body portion, and first and second vanes attached to said central body portion, said first and second vanes sealingly engaging said valve seating means when said valve closure means is in said closed position, the peripheral edge of said first vane lying in a first plane eccentrically disposed to said axis of rotation, the peripheral edge of said second vane lying in a second plane eccentrically disposed to said axis of rotation, said first and second planes being noncoincident and on opposite sides of said axis of rotation wherein said first and second planes are substantially parallel wherein said central body portion comprises a pair of cylindrical, co-axial members one end of each of which intersects and extends from a pair of dome shaped members joined at their bases, the diameter of said cylindrical members being substantially equal to the perpendicular distance between the apexes of said dome shaped members, a plane passing through the intersection of said dome shaped members being coincident with a diameter through said cylindrical members, each of said vanes comprising a flat, subStantially semi-annular member having first and second faces, respective ends of said semiannular members being adjoined to said cylindrical members adjacent the free ends of said cylindrical members, said first face of said semi-annular member comprising said first vane lying in a plane substantially tangential to the surface of said cylindrical members and the apex of one of said dome shaped members, said first face of said semi-annular member comprising said second vane lying in a plane substantially tangential to the surface of said cylindrical members and the apex of the other of said dome shaped members, said first and second vanes further comprising curved sections which adjoin said semi-annular flat members to said central body portion, said curved section comprising said first vane constituting an extension of one of said dome shaped members and being adjoined to the inside periphery of said semi-annular member of said first vane, said curved section comprising said second vane constituting an extension of the other of said dome shaped members and being adjoined to the inside periphery of said semi-annular member of said second vane, the outside surfaces of each of said dome shaped members and the connecting curved surfaces being at all points of their intersection smooth and uniform, said second faces of said semi-annular members lying in non-coincident planes.