BALANCED VALVE WITH PRESSURE SENSING MEANS

摘要

BALANCED VALVE WITH PRESSURE SENSING MEANS An improved balanced valve includes a body having a cylindrical valve chamber and a pair of flow passages intersecting the lower portion of the chamber. An annular valve seat is located between the lower portion and a first of the flow passages and is coaxially aligned with the cylindrical valve chamber. A main valve disc assembly is mounted for axial movement within the cylindrical valve chamber for selective engagement of a main disc thereof with a seat and further includes a concentric hollow body extending from the main disc away from the seat and terminating at a piston fitting which is slidably received within an upper portion of the cylindrical valve chamber. A coaxially aligned valve stem extends from an operating mechanism located above the valve through the upper portion, the piston fitting and the hollow body to terminate at an auxiliary valve disc. An axial opening through the main valve disc assembly allows communication between a region above the disc assembly and a region below the main disc to substantially control fluid forces acting on the opposite sides of the main valve disc assembly to facilitate opening and closing of the valve. Control of the fluid forces is partially obtained through predetermined axial positioning of the auxiliary valve disc during operation of the valve stem to open and close the axial opening through the main valve disc assembly. The improvement includes a radial array of pressure sensing passages in the main disc which extend from the axial opening to a peripheral region of the disc below the seating surface of the disc. As fluid flows from the second to the first flow passage, as when there is a rupture of the first flow passage, an upward force is generated on the main disc just prior to closure which tends to resist the closing force on the valve. The pressure sensing passages allow a higher fluid pressure to be communicated to the region above the main valve disc assembly to effectively oppose this resistance to closure.