US 4,727,903 AGranted

Fluid shutoff valve

AssigneeMalcolm B. Sturgis

InventorsMalcolm B. Sturgis, Richard E. Hoffman

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Abstract

An excess pressure and/or excess flow/temperature shutoff valve comprising a valve housing having an axial bore therethrough with inlet and outlet ends, a portion of the bore being enlarged to form a valve chamber, and a spool movable in the valve chamber and having a sealing fit with the walls of the chamber. In the event of an upstream pressure increase of predetermined magnitude, the spool is adapted to move from an open position in which it permits flow of fluid through the bore to a position wherein additional spool area is exposed to the upstream fluid pressure, whereupon the spool is adapted to move further downstream to a shut off position for blocking the flow of fluid through the bore. The valve may be optionally equipped to shut off the flow of fluid in the event of a downstream pressure decrease as a result of excess leakage and/or an increase in fluid temperature in excess of a predetermined value.

Claims25

Dependent claims

A fluid shutoff valve comprising a valve housing having an axial bore therethrough with inlet and outlet ends, said bore being enlarged between said inlet and outlet ends to form a valve chamber comprising a first portion bounded by a first annular wall extending generally axially of the valve housing and a second portion downstream from the first portion bounded by a second annular wall extending generally axially of the valve housing, said second annular wall having an inside diameter greater than the inside diameter of said first annular wall thereby to form internal shoulder means in the valve chamber, valve means in said valve chamber having a passage for the flow of pressurized fluid from the inlet end of the bore to the outlet end of the bore, said valve means having a first valve portion received in said first portion of the valve chamber and a second valve portion downstream from the first valve portion received in said second portion of the valve chamber, said second valve portion having an outside diameter greater than the outside diameter of said first valve portion thereby to form external shoulder means on said valve means, first seal means providing a sealing fit between said first valve portion and said first annular wall of the valve chamber and second seal means providing a sealing fit between said second valve portion and said second annular wall of the valve chamber, said valve means being movable in the valve chamber between an open position permitting flow from the inlet end of the bore to the outlet end of the bore via said valve passage and a shutoff position blocking said flow, and spring means biasing said valve means toward said open position, the arrangement being such that said valve means is responsive to an increase in upstream fluid pressure of predetermined magnitude to move downstream in the valve chamber a sufficient distance relative to said internal shoulder means to break the sealing fit provided by said first seal means whereby said external shoulder means on said valve means is exposed to said upstream fluid pressure and said valve means is adapted to move further downstream to said shutoff position.

A fluid shutoff valve comprising a valve housing having an axial bore therethrough with inlet and outlet ends for flow of pressurized fluid therethrough, said bore being enlarged between said inlet and outlet ends to form a valve chamber extending generally axially with respect to the housing and having a relatively large-diameter portion and a relatively small-diameter portion downstream from the large-diameter portion, valve means in said valve chamber having a passage communicating at one end thereof, constituting its inlet end, with said large-diameter valve chamber portion and communicating at its other end, constituting its outlet end, with said small-diameter valve chamber portion for flow of pressurized fluid from the inlet end of the bore to the outlet end of the bore, said valve means comprising a valve head in said large-diameter portion of the valve chamber and a valve stem extending axially from the head into said small-diameter portion of the valve chamber, said valve head having upstream and downstream faces extending generally radially with respect to the valve housing and further having a diameter substantially greater than the diameter of said valve stem, upstream seal means disposed between said upstream and downstream faces of the valve head providing a sealing fit between said valve head and wall of the large-diameter portion of the valve chamber, downstream seal means providing a sealing fit between said valve stem and wall of the small-diameter portion of the valve chamber, a passageway in the valve housing communicating with said large-diameter chamber portion for exposing said downstream face of the valve head to ambient pressure, a valve seat in the bore adjacent its outlet end, said valve means being movable in the valve chamber between an open position permitting flow from the inlet end of the bore to the outlet end of the bore via said valve passage and a shutoff position in which said valve stem is sealingly engageable with said bore valve seat for blocking said flow, and spring means biasing said valve means toward said open position, the arrangement being such that said valve means is responsive to an increase in upstream fluid pressure of predetermined magnitude to move downstream in the valve chamber against the bias of said spring means and ambient pressure from its open position to its shutoff position.

Dependencies are inferred from the claim text.