Patent ID: 6513541
Filing Date: 2003-02-04
Classification: F16K,F16L,Y10T

Abstract:
A pipeline vent valve comprising a body defining a chamber having an inlet towards its lower end which is adapted to be connected to a pipeline and an outlet towards its upper end, the outlet defined by a valve seat, a first valve member supported in the chamber to be moveable between a first position at which it is in sealing engagement with the valve seat and a second position at which it is out of engagement with the valve seat, said first valve member in its movement to the first position being responsive to the magnitude of the gaseous flow rate through the valve seat to be moveable to the first position on the gaseous flow rate exceeding a desired level, said first valve member also being responsive to the level of liquid in the chamber and being adapted to close when the liquid level in the chamber exceeds a predetermined level, said first valve member having an opening providing communication to each side of the first valve member, wherein the opening has a divergent cross-section which is substantially constant throughout its extent between each side of the first valve member, a second valve member fixed to the first valve member to depend from the first member and to be moveable between a first position at which it is in sealing engagement with the entry of said opening and a second position at which it is out of engagement with the entry of said opening, and wherein the second valve member comprises a flexible membrane having a first portion adjacent to the most divergent portion of the opening, a float member fixed to the flexible membrane at a second portion spaced from the first portion, said valve member being adapted to flex, whereby on movement of the second valve member from the second position to the first position the second valve member increasingly engages across the entry of the opening from the most divergent portion of the opening to the most convergent and on movement of the second valve member from the first position to the second position the second valve member decreasingly engages across the entry of the opening from the most convergent portion of the opening to the most divergent portion, the float member supported within the chamber and fixed to said second valve member to cause movement of the second valve member between the first and second position as a result of movement of the float member resulting from the presence of liquid in the chamber, wherein movement of the first valve is in response to the absence of liquid within the chamber which is independent of movement of the float member.