Non-return valve

Claim 1

In a non-return valve including a housing defining therein a passage with two spaced discharge apertures, a valve body having a flat side for seating, and being movable between a closed position and an open position, and means for moving said valve body between said positions, the improvement in combination therewith of a valve seat comprising an annular body situated in said housing and sealingly blocking said passage except for a duct extending through said body, said valve seat having a top side including an aperture therein which is one outlet of said ducT, said valve body when in closed position having its flat side cooperating with said top side of the seat for blocking said duct aperture, said top side being a surface defined as: a first inner circular part adjacent and outward of said aperture, a second middle circular part adjacent and outward of the first part, and a third outer circular part adjacent and outward of the second part, these first, second and third parts (when said body is cut by a vertical plane through the axis of said duct) defining on each side of said axis a profile wherein said second part is a generally horizontal line, the first part is a convex curve projecting above said line, the curve having a top that is flat and generally horizontal to said axis, the third part is a generally rectangular area projecting above said line to a height less than said curved part, and said valve body flat part having diameter similar to that of said first part for cooperation therewith.