Safety relief valve for pressure vessels

A fluid pressure relief system for a pressure vessel comprising:

• a tubular housing projecting above said pressure vessel;
• a nozzle mounted on an upper end portion of said housing and defining an upper valve seat forming a vent for an upper portion of the pressure vessel;
• a main valve member seated on said valve seat under a mechanical force of a predetermined amount for holding said main valve member in closed position on said valve seat under normal operating fluid pressure within said pressure vessel;
• an operating rod within said pressure vessel having an upper end secured to said main valve member;
• a piston within said pressure vessel secured to said operating rod adjacent the lower end thereof;
• a cylinder within said pressure vessel receiving said piston for reciprocable movement and defining a fluid chamber adjacent one side of said piston with the other side of said piston in continuous fluid communication with the interior of said pressure vessel without any substantial flow restriction therebetween;
• and
• fluid conduit means defining a fluid passage between said fluid chamber and said main valve member, said fluid conduit means having a lower inlet in fluid communication with said fluid chamber and an upper outlet adjacent said nozzle to permit the flow of fluid from said fluid chamber through said fluid conduit means upon opening of said main valve member thereby to provide a fluid pressure differential on opposed sides of said piston.

In a fluid pressure relief system for a pressure vessel having a valve seat member defining a vent;

• a main valve member seated on said valve seat member under a mechanical force of a predetermined amount and having an upstream side in continuous fluid communication with fluid pressure within the pressure vessel;
• an operating member operably connected adjacent one end to said main valve member;
• a fluid pressure responsive member operably connected to said operating member adjacent the other end thereof;
• a fluid chamber adjacent one side of said fluid pressure responsive member with the other side of said fluid pressure responsive member in fluid communication with the interior of said pressure vessel;
• and
• fluid conduit means defining a fluid passage between said fluid chamber and said main valve member, said fluid conduit means having an inlet adjacent said fluid chamber and an outlet adjacent said main valve member on said upstream side thereof at said valve seat member to permit fluid flow from said fluid chamber upon opening of said main valve member whereby a fluid pressure differential is provided on opposite sides of said fluid pressure responsive means upon an increase in fluid pressure within said pressure vessel resulting from a flow of fluid from said outlet as said valve seat member;
• said fluid pressure responsive member comprising a piston mounted within a cylinder forming said fluid chamber adjacent one said of said piston;
• said cylinder including a cylindrical body and an upper end over said cylindrical body;
• said piston, cylindrical body and upper end being formed of a similar plastic material to provide the same rate of thermal expansion, said cylindrical body and said upper end being unsecured to each other.

A fluid pressure relief system for a pressure vessel comprising:

• a nozzle defining an upper valve seat forming a vent for the pressure vessel;
• a main valve member seated on said valve seat under a mechanical force of a predetermined amount for holding said main valve member in closed position on said valve seat under normal operating fluid pressure within said pressure vessel;
• an operating rod secured adjacent one end to said main valve member;
• a piston secured to said operating rod adjacent the other end thereof;
• a cylinder receiving said piston for reciprocable movement and defining a fluid chamber adjacent one side of said piston with the other side of said piston in fluid communication with the interior of said pressure vessel;
• fluid conduit means defining a fluid passage between said fluid chamber and said main valve member, said fluid conduit means having an inlet adjacent said fluid chamber and an outlet adjacent said nozzle to permit the flow of fluid from said fluid chamber upon opening of said main valve member thereby to provide a fluid pressure differential on opposed sides of said piston;
• and
• a vacuum valve member mounted on said operating rod for relative sliding movement and spring urged into sealing relation with said main valve member, said main valve member having a central opening therethrough and said vacuum valve member closing said central opening under normal operating pressure within said pressure vessel, said vacuum valve member opening upon a predetermined negative pressure within said pressure vessel to permit fluid flow within said pressure vessel through said central opening of said main valve member.

A method of providing a fluid pressure relief system for a pressure vessel having a nozzle forming a vent and a main valve member seated on said nozzle;

• said method comprising the following steps:
• providing a mechanical force of a predetermined amount against said main valve member to hold said main valve member in seated position against said nozzle under normal operating fluid pressures;
• operably connecting a fluid pressure responsive member to said main valve member with one side of said fluid pressure responsive member in fluid communication with the interior of the pressure vessel;
• providing a separate fluid chamber on an opposed side of said fluid pressure responsive member;
• providing a fluid passage from said separate fluid chamber to an outlet closely adjacent said nozzle whereby upon unseating of said main valve member at a predetermined fluid pressure within said pressure vessel, fluid flows from said separate fluid chamber through said outlet to reduce the fluid pressure therein and thereby provides a fluid pressure differential acting against said fluid pressure responsive member to assist in opening of said main valve member;
• providing a piston for said fluid pressure responsive member;
• providing an operating rod secured at one end to said main valve member and secured at an opposite end to said piston thereby to effect simultaneous movement of said piston and main valve member;
• and
• mounting a vacuum valve on said operating rod for relative movement to an open position upon the reaching of a predetermined low pressure within said pressure vessel.

In a fluid pressure relief system for a pressure vessel having an upper valve seat member defining a vent adjacent the upper portion of said pressure vessel;

• a main valve member seated on said valve seat member under a mechanical force of a predetermined amount and having an upstream side in continuous fluid communication with fluid pressure within the pressure vessel;
• an operating member operably connected adjacent one end to said main valve member for movement of said main valve member in an upward direction for opening thereof;
• a fluid pressure responsive member operably connected to said operating member adjacent the other end thereof;
• a fluid chamber adjacent one side of said fluid pressure responsive member with the other side of said fluid pressure responsive member in continuous fluid communication with the interior of said pressure vessel;
• fluid conduit means defining a fluid passage between said fluid chamber and said main valve member, said fluid conduit means having an inlet in fluid communication with said fluid chamber and an outlet adjacent said main valve member on said upstream side thereof at said valve seat member to permit fluid flow from said fluid chamber upon opening of said main valve member whereby a fluid pressure differential is provided on opposite sides of said fluid pressure responsive member upon an increase in fluid pressure within said pressure vessel resulting from a flow of fluid from said outlet at said valve seat member;
• and
• flow control means of a predetermined size between said fluid chamber and the interior of said pressure vessel in continuous fluid communication with the interior of said pressure vessel for controlling fluid flow through said fluid conduit means upon opening of said main valve member thereby to control the sensitivity of the main valve member after opening.