Balanced valve port for fluid regulator

摘要

A balanced port control assembly includes a control element with a valve plug coupled to a valve stem and a pressure sensing labyrinth defined at least partly by the valve plug. The pressure sensing labyrinth provides for fluid communication between a sealing surface of the valve plug and a balancing diaphragm carried internally of the control element. The pressure sensing labyrinth includes at least one pressure sensing passage extending from the sealing surface and into the valve plug along a central longitudinal axis of the control element. So configured, fluid pressure resident on the sealing surface of the valve plug is also resident on the balancing diaphragm such that equal and opposite forces are applied to the control element.

主权项

1. A fluid regulating device comprising: a valve body defining an inlet, an outlet, and a valve port disposed between the inlet and the outlet; a port housing disposed in the valve body and defining a central cylindrical opening; a control element at least partly slidably disposed in the central cylindrical opening of the port housing and adapted for displacement along a central axis of the control element between a closed position engaging the valve port and an open position spaced away from the valve port, wherein the control element comprises a valve stem and a valve plug coupled to the valve stem, the valve plug defining a sealing surface adapted to sealingly engage the valve port when the control element is in the closed position; a balancing diaphragm coupled between the control element and the port housing, the balancing diaphragm having opposite first and second diaphragm surfaces; a balancing cavity defined in a portion of the port housing between an inner surface of the port housing and the first diaphragm surface of the balancing diaphragm; and a first pressure sensing passage extending through the valve plug and in fluid communication with the balancing cavity such that a fluid pressure resident on the sealing surface of the valve plug is equal to a fluid pressure resident in the balancing cavity to apply equal and opposite first and second forces to the sealing surface of the valve plug and the first surface of the balancing diaphragm, respectively, the first pressure sensing passage having an inlet portion extending through the valve plug along the central axis of the control element, and wherein the valve plug comprises at least one of:
(a) a central bore extending along the central axis of the control element and a plug fastener disposed in the central bore and fixing the valve plug to the valve stem, the plug fastener defining at least a portion of the inlet portion of the first pressure sensing passage; and (b) an outer plug portion, an inner plug portion disposed radially inside of the outer plug portion, and at least one intermediate passage disposed between an outer wall of the inner plug portion and an inner wall of the outer plug portion, wherein the at least one intermediate passage defines at least one second pressure sensing passage extending through the valve plug and in fluid communication with the balancing cavity.