Valves or cocks with rotary plug in which the plug is provided with flexible gaskets of annular shape located symmetrically with respect to the plane passing through the axis of rotation of the plug and the axis of the cylindrical conduit of the plug, PLUG VALVESsealing seats borne by the valve body, the seats being arranged in such a manner that they come into contact with the gaskets borne by the plug when the latter is in closed position. A valve comprising a valve body having an inlet and an outlet; a plug having a fluid passage therein;Balance Valves means for rotatably mounting said plug in said valve for movement between an open position in which said passage communicates with both said inlet and said outlet and a closed position in which said passage is out of such communication,Needle & Gauge Valves said plug having a pair of opposed spherical surface portions defined by a sphere having a center located at the intersection of the axis of rotation of said plug and the axis of said passage; and means for sealing said valve in said closed condition comprising a pair of annular sealing gaskets secured respectively to said spherical surface portions of said plug; a pair of sealing seats mounted on said valve body in surrounding relation with said inlet and outlet, each of said sealing seats including a fixed annular member secured to said valve body, an annular bearing member mounted for axial movement relative to said fixed annular member, means for biasing said annular bearing member toward said plug, the portion of each bearing member engageable by said annular gasket having a spherical surface portion, additional rotary movement of said plug toward said closed position being effective for moving said annular bearing member adjacent said biasing means, each movable bearing member having said spherical surface portion flanked by a marginal recessed toric surface symmetrically disposed with respect to the axis of rotation of said plug on said spherical surface portions so as to form a marginal groove adjacent said bearing member spherical surface portion, said gaskets having compressible portions protruding beyond said plug surface for progressive free engagement within said marginal groove and subsequent compressive engagement with said spherical surface portions to complete said valve seal when said plug is moved into said closed position, the portions of said sealing seats engageable by said gaskets being in the form of portions of a sphere having the same center as said spherical surface portions of said plug, said protruding portion being progressively deformable against said spherical surface portions as said protruding portion moves into engagement therewith from said marginal toric surface upon said plug being moved into said closed position, said protruding portion being in a non-deformed released configuration unless said plug is adjacent said closed position.

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