Abstract: There is a balanced plug valve with a contour shaped wall. The contour shaped wall forms a gap with an edge of a balanced plug. Fluid is able to flow through an input port, through the balanced plug, through the gap, and out an output port. The shape of the contour and the relative position of the balanced plug to the contour shaped wall affect the modulation of the rate of the fluid flow through the gap, and thus, through the valve. Multiple possible variations of the dimensions of the contour shaped wall make possible a multitude of flow rate verses valve stroke relationships. Further, the use of a balanced valve decreases friction forces on the plug which allows for smaller, more efficient, and more economical valve actuators.

Abstract: A stem seal having first and second wiping members circumjacent a stem is disposed within a bore. A lubricant-bearing ring is disposed about the stem within the bore between the wiping members, under compression therefrom. Projections from the wiping members intrude into the lubrication ring so as to depress the central surface areas thereof. Similar projections are used to center a coil spring against one of these seal members and against an additional seal member. By forming the lubricant ring of open-cell loam or mesh construction, superior lubricant bearing capacities may be achieved.