US 5,555,910 AGranted

Pressure relief valves adapted for low pressure operation

AssigneeGroth Corporation

InventorsWalter W. Powell, Milton N. Anderson, Jr., Louis R. Castaneda, Aciel Martin

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Abstract

A safety relief valve (10) having a main valve member (22) in a normally closed seated position has a diaphragm actuator (24) with a dome chamber (34) adjacent the outer side of the diaphragm (26). A pilot valve (28) is in fluid communication with the dome chamber (34) through a dome line (35) for controlling the opening and closing of the main valve member (22). An underdome chamber (40) on the inner side of the diaphragm (26) has an underdome line 44 extending to an underdome control valve (42) for controlling fluid communication to underdome chamber (40) from the inlet (18). An inlet line (48) extends from the inlet (18) to the underdome control valve (42). When the set pressure of the pilot valve (28) is reached, inlet fluid pressure on the inner side of the diaphragm (26) increases while dome pressure in the dome chamber (34) decreases. Simultaneously, an increase in fluid inlet pressure at inlet (18) actuates underdome control valve (42) to provide direct fluid communication between inlet (18) and underdome chamber (40) to boost the opening of main valve member (22). One embodiment of the invention shown in FIGS. 6 and 7 utilizes a non-pilot operated relief valve member (10C) in which a weight (29C) urges the main valve member (22C) into closed position. An underdome control valve (42C) includes a weight (65C) urging the underdome control valve member (67C) into a seated position.

Claims16

Dependent claims

A safety relief valve for a pressure vessel adapted to permit fluid flow from said pressure vessel at a predetermined fluid pressure in the pressure vessel;

said safety relief valve comprising:
a valve body having an inlet in fluid communication with said pressure vessel and an outlet leading from said valve body;
a main valve member within said valve body mounted for movement between open and closed positions relative to said inlet to permit fluid flow from said outlet upon movement of said valve member to an open position;
a fluid pressure responsive control member for said main valve member secured to said main valve member for movement therewith between open and closed positions;
a dome chamber in said valve body on the side of said fluid pressure responsive control member opposite said main valve member;
a pilot valve in fluid communication with said dome chamber for controlling the movement of said main valve member;
an underdome chamber in said valve body on the opposite side of said fluid pressure responsive control member adjacent said main valve member;
an underdome control valve to control fluid communication to said underdome chamber from said inlet;
a fluid line from said inlet to said underdome control valve;
and
an underdome fluid line from said underdome control valve to said underdome chamber;
said underdome control valve including an underdome valve member in a normally closed position blocking fluid communication from said inlet to said underdome chamber and permitting fluid communication from said inlet to said underdome chamber in an open position;
said valve member being in continuous fluid communication with said inlet through said inlet fluid line and moving to an open position upon the reaching of a predetermined fluid pressure at said inlet thereby to increase the fluid pressure in said underdome chamber for assisting opening of the main valve member;
said pilot valve being in fluid communication with said underdome control valve to assist movement of said underdome control valve to an open position upon a predetermined increase in fluid pressure in said pressure vessel.

11 more elements

An improved pilot operated safety relief valve for a pressure vessel adapted to permit fluid flow from said pressure vessel at a predetermined fluid pressure in said pressure vessel;

including
a valve body having a main valve chamber with an inlet and an outlet, and a main valve member within said valve body mounted for movement between open and closed positions relative to said inlet to permit fluid flow from said outlet upon movement of said valve member to an open position;
a diaphragm in said main valve chamber and a stem connecting said diaphragm to said main valve member for simultaneous movement;
said diaphragm defining a dome chamber on one side thereof remote from said main valve member and an underdome chamber on the other side thereof adjacent said main valve member;
and
a pilot valve connected to said relief valve including a sensing chamber in fluid communication with said inlet and said pressure vessel, and a relief port to bleed fluid from said dome chamber when the fluid pressure in said pressure vessel reaches a predetermined amount at the set pressure of said pilot valve to effect movement of said diaphragm and opening of said main valve member;
wherein improvement is characterized by
an auxiliary pressure boost means to assist in the initial movement of said diaphragm and opening of said main valve member;
said auxiliary pressure boost means comprising:
an underdome chamber in said main valve chamber on the other side of said diaphragm opposite said dome chamber;
and
underdome control valve means for controlling the supply of fluid from said inlet to said underdome chamber, said underdome control valve means providing direct fluid communication between said inlet and said underdome chamber at the set pressure of said pilot valve, said underdome control valve means connecting said underdome chamber to atmosphere at a pressure below the set pressure of said pilot valve, said pilot valve being in fluid communication with said underdome control valve means to assist movement of said underdome control valve means to an open position permitting inlet fluid to said underdome chamber.

9 more elements

Dependencies are inferred from the claim text.