Control valve trim assembly

摘要

Described herein are fluid flow control valve trims suitable for use in a valve in which high fluid pressure drops are to be sustained without excessive noise generation or cavitation damage to valve members. The valve trim is constructed of two or more annular cages surrounding a central passageway, each outer cage circumferentially engaging the next inner cage. A valve stem carrying a valve plug member is axially movable within the central passageway, the plug member slidingly engaging the radially inward surface of the innermost annular cage. Communicating through the walls of each of the cages are flow-restricting orifices and fluid pressure recovery chambers defining two or more sequential orificial throttling stages. By the use of concentric annular cages a valve trim structure is achieved in which the flow-restricting orifices and pressure recovery chambers may readily be formed having reproducible, predetermined sizes and shapes by conventional machining operations.