HK1237392B - Through wall connector for a multi-chamber pressure vessel - Google Patents

Description

Through-connections for multi-chamber pressure vessels

Technical Field

The present application relates to a novel connector for providing an air-tight and liquid-tight connection between a water inlet pipe and an inner chamber of a multi-chamber pressure vessel.

Background Art

Multi-chamber tanks (typically comprising two chambers separated by an at least partially flexible non-metallic membrane) are very common in the water storage industry, used to store, for example, drinking well water. These multi-chamber containers, primarily used to store aqueous liquids, typically include a metal (e.g., steel or aluminum) outer container and a non-metallic inner water-holding container. Maintaining a liquid-tight and air-tight separation between these two volumes has been difficult. This difficulty and long-standing problem involves connecting a metal water inlet pipe to the non-metallic inner container wall using a durable air-tight and liquid-tight seal that also forms a hermetic seal against the outer metal wall.

Summary of the Invention

The present invention differs from the prior art in that it provides a permanently fixed connection between the inner wall (partly formed by a flexible diaphragm) that separates the water liquid chamber of the tank from the air gas chamber, which provides a completely secure watertight and airtight connection to avoid any potential possibility of gas leaking into the liquid (e.g., drinking water) in the diaphragm chamber, or the possibility of liquid entering the gas chamber and indirectly coming into contact with the wall of the metal tank, which could potentially damage the tank.

According to the present invention, a diaphragm tank is provided, comprising: an outer rigid shell, typically made of steel or other strong, typically metallic material, but sometimes made of a rigid and reinforced polymer or composite material; an inner tank separated from the outer tank wall by a wall to separate a chamber containing a liquid from a gas pressure chamber located outside a flexible diaphragm between the two chambers, wherein the wall is formed by a combination of flexible diaphragms sealably connected to a lower, more rigid wall; and a rigid liner sealingly connected to the flexible diaphragm and combined with the diaphragm to separate the water liquid chamber from the air gas chamber. The "liner" can also be replaced by a second diaphragm, wherein the water liquid chamber is fixed between the two diaphragms, one of which can be fully flexible and the second diaphragm partially flexible or substantially rigid; the lower wall becomes substantially rigid at the location of the permanent seal between the lower wall and the liquid inlet connection. The connection piece of the invention is preferably fixed to the lower wall of the inner volume, ie to the more rigid wall or the flexible membrane separating the inner and outer tank volumes.

Further defining the present invention, the liquid inlet includes a male connection gland that is permanently affixed to or integrally formed with a wall of the inner liquid chamber, preferably the more rigid lower wall. The inner liquid chamber wall is preferably a rigid or partially flexible diaphragm that is separated from the outer wall of the rigid gas chamber within the pressure vessel to provide a gas-tight and liquid-tight attachment between the inner chamber wall and the liquid inlet. By substantially integrating the male gland with the inner chamber, additional elements or components previously required to implement a liquid-tight through-wall connection are eliminated, thereby avoiding and preventing manufacturing errors that often occur during assembly.

The present invention provides for essentially complete integration of an inner chamber wall and a through-wall connector, referred to as a "male gland," to provide the required air and liquid flow seals in both directions between the pressurized gas chamber and the inner liquid chamber, while eliminating the complex mechanisms previously used in the industry. The portion of the male gland that extends through the lower inner wall into the liquid chamber is preferably a continuation of a flow tube having a circular cross-section of sufficient diameter to carry the desired liquid flow into the inner chamber. A solid upper flange extends outwardly around the tube but below the upper outer end of the flow tube. The solid upper flange is integral with the tube and is preferably made of the same material as the tube portion. The outer periphery of the upper flange is also preferably circular and has a diameter that is preferably at least approximately twice the outer diameter of the tube portion that extends through the lower inner wall into the inner chamber.

The tube portion of the convex gland extends downwardly through the gas-filled outer intermediate chamber and is preferably long enough to extend through and below the bottom surface of the outer rigid wall of the tank. A lower flange extends radially outwardly from the tube portion of the convex gland vertically below the upper flange at a location along the tube designed to rest on the inner surface of the outer rigid wall of the tank. The portion of the convex gland extending below the outer rigid wall container includes a circumferential sealing member to maintain an airtight and liquid-tight seal between the convex gland and an inlet tube for allowing liquid to flow into the inner chamber. According to the present invention, the liquid inlet portion of the convex gland leading to the inner chamber is connected to the lower diaphragm or liner and is thereby formed to assist in maintaining separation between the outer chamber between the diaphragm and the outer rigid wall and the inner chamber within the inner diaphragm/liner wall.

The portion of the male gland extending below the outer rigid wall of the tank extends into and sealingly secures to the external liquid inlet tube, which is preferably an elbow extending below the rigid bottom wall of the outer tank. The inner surface of the vertically extending upper portion of the external liquid inlet tube forms a sealing engagement with the lower portion of the male gland. Extending outwardly around the periphery of the upper end of the external inlet tube is a flange and a short lip, which extends upward from the flange and extends through the rigid outer wall of the tank, preferably so as to contact the lower surface of the lower flange of the male gland. In this way, the connection between the external inlet tube and the male gland is maintained to maintain the integrity of the system and isolate the pressure chamber from any liquid contaminants.

In operation, the system provides for changing the pressure within the pressurized gas chamber as the liquid chamber fills with liquid, pushing the flexible diaphragm upward and outward, thereby reducing the volume of the sealed intermediate chamber and necessarily increasing the gas pressure within the sealed intermediate gas chamber independently of the external pressure acting on the outer rigid walls of the tank. The pressures in both the water liquid chamber and the air gas chamber change simultaneously due to the change in volume of the water liquid entering the water liquid chamber. Typically, the inner chamber is intended to hold a liquid, typically water, while the outer chamber holds a compressible gas, which can be air or, if desired, an inert material such as nitrogen, helium, or other inert gas, preferably remaining in a gaseous state under any expected pressure conditions under any possible environmental conditions.

Further defining the invention, the water inlet includes a male connection gland that is permanently affixed to or forms a portion of the lower inner chamber wall. The lower inner chamber wall can be a liner located on the inner surface of the outer steel wall or the inner shell, the liner being less flexible than the upper diaphragm and separate from the rigid chamber wall, the liner being sealingly connected to the male connection gland to maintain an air-tight and liquid-tight attachment between the inner chamber wall and the water inlet. The substantially integrated male gland and inner chamber serve to eliminate additional elements or components previously required to implement liquid-tight through-wall connections, thereby avoiding and preventing manufacturing errors that often occur during assembly.

The male gland is connected to the external water inlet, ensuring that the liquid remains within the gland and inlet, exiting the tank's interior chamber without exiting the tank's pressure chamber. Conventional water pipe sealing elements can be used between the portion of the external water inlet extending from the pressure tank and the water inlet pipe. Furthermore, a sealing element is provided between the external water inlet and the outer wall of the pressure tank to prevent air or water from entering the pressure chamber through the passageway and thereby altering the pressure within the tank's pressure chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be more clearly understood after referring to the following detailed description considered in conjunction with the following drawings:

1 is a cutaway elevational view of a dual-chamber pressure tank having a partially extended inner diaphragm and a partially enlarged view of an inlet connector located between the inner liquid chamber and the liquid inlet;

FIG2 is an enlarged isometric view of the lower portion of the tank of FIG1 showing the fluid-gas isolation elements of the connecting coupling and the joint in greater detail;

FIG3 is an exploded front view of a dual-chamber pressure tank of the present invention;

FIG4 is an enlarged isometric view of the lower portion of the inner tank of FIG1 ;

FIG5 is an enlarged front view of an embodiment of a convex sealing gland of the present invention;

FIG6 is a cross-sectional view of the male sealing gland of FIG5 taken along line A-A;

FIG7 is a top isometric view of the convex sealing gland of FIG5;

FIG8 is a side isometric view of the inlet elbow of the outer tank of FIG1 ;

FIG9 is a cutaway elevational view of a dual-chamber pressure tank of the present invention; and

FIG10 is an enlarged cross-sectional view of the male gland 15 tightly positioned around the outer rigid wall of the tank, the wall of the lower liner and the sealing connection.

DETAILED DESCRIPTION

The assembly of the present invention provides fluid communication between the exterior and interior of a pressure vessel while maintaining the integrity of the pressure vessel and isolating the pressurized gas chamber of the pressure vessel from the internal liquid holding chamber. Isolating the pressurized gas chamber from the interior chamber provides for pressure variations without being affected by atmospheric pressure outside the pressure vessel.

The outer wall of the tank 12 is preferably a steel shell formed from three sections: a top cover 28, a central cylinder 26, and a lower cup 18, all formed from steel or other rigid, preferably metallic, material. Supported within the outer wall of the tank 12 is an inner liquid chamber defined by at least one flexible diaphragm 14 and a lower liner 16; the lower liner can be flexible or rigid, or can be a liner at least partially fixed to the inner surface of the outer rigid wall of the tank. The lower liner 16 is in turn connected to the male gland 15 of the present invention. Other rigid materials that can be used to form the outer rigid wall of the tank include other metals, particularly aluminum or aluminum alloys, and certain polymers, such as polycarbonate or composite structures.

Lower liner 16 and flexible diaphragm 14 define an internal chamber for holding liquid entering through inlet elbow 20 and male gland 15. As liquid fills the internal volume, the pressure in the intermediate gas volume (between the diaphragm and the outer rigid wall of the tank) increases as flexible diaphragm 14 is pushed upward and outward by the filling of water, thereby reducing the volume of the intermediate space between the internal chamber and the outer rigid wall of the tank. The two parts of the wall of the internal volume (flexible diaphragm 14 and lower liner 16) are held together by a clamp ring 24, which provides a permanent bond while eliminating the possibility of gas leakage into the internal volume or liquid leakage outward into the intermediate gas space. Flexible diaphragm 14 and lower liner 16 can be formed from a polymer (such as polypropylene or polyethylene) or, in the case of the flexible diaphragm, an elastomeric compound (such as butyl rubber, ethylene propylene diene monomer (EPDM), styrene butadiene rubber (SBR), neoprene, or latex rubber).

The male gland, generally designated 15, is preferably rigid and can be formed, for example, of reinforced polypropylene or polyethylene or any suitable copolymer, or polycarbonate or other polymer (preferably a cross-linked thermoset polymer). The connection between the male gland and the lower liner/diaphragm is formed, for example, by fusing the upper flange 115 of the male gland to the outer surface of the bottom of the lower liner 16. This fusing can be achieved by welding, i.e., melting a thermoplastic copolymer material, thereby permanently welding the two elements together, or by using an intermediate material that is compatible with the materials forming the upper flange 115 and the lower liner 16.

The male gland 15 is formed from a substantially rigid polymeric material, such as reinforced polycarbonate, polypropylene, or polyethylene, or suitable copolymers thereof, or a thermosetting polymer. The connection between the male gland 15 and the lower surface of the wall of the lower liner 16 is formed by fusing the upper flange 115 of the male gland to the outer surface of the lower liner 16. The connection between the upper flange 115 and the outer surface of the lower liner 16 can be achieved, for example, by welding or by using an intermediate material that will be permanently fused to the materials forming the upper flange and lower liner, depending on the relative weldability of the materials forming the upper flange and lower liner.

As shown in the drawings, the male gland has a grid of vane elements 116, 121, 126 at its upper end surrounded by an upper flange 115. These grid elements extend a short distance above the upper flange 115 surrounded by a short tube portion 146 and serve to direct any flow upward from or downward to the metal inlet elbow 20.

The inlet elbow 20 is sealably connected to a lower extension 215 that extends vertically downward from the outer wall of the tank. The metal inlet elbow 20 is coupled to the lower extension of the male gland via a slip fit, which is sealed using an O-ring 136 within a circumferential groove 137 in the lower extension 215 of the male gland. The distal end 140 of the inlet elbow 20 can be connected to the inlet and outlet piping by any suitable pipe connection means. Such connection means may include brazing, threaded connections, or other suitable means, and do not form part of the present invention.

The upper flange 143 of the inlet elbow 20 is circumferentially welded to the outer surface of the metal outer wall of the tank 12. To further complete the seal of the metal elbow to the metal outer wall of the tank, additional O-rings are provided between the outer periphery of the upper end 142 of the inlet elbow, the outer rigid wall of the tank, and the lower flange 118 of the male gland. In this way, a seal is formed between two dissimilar materials (i.e., between the metal forming the inlet elbow and the outer wall of the tank, and between the polymer forming the male gland 15 and the outer wall of the tank) to ensure that when water enters the inner chamber and expands the volume of the inner chamber by pushing the flexible diaphragm 14 upward and outward, thereby increasing the pressure in the intermediate volume between the inner and outer tanks, there is no leakage from the gas volume to the liquid or to the outside of the outer tank, and thus no pressure loss.

In fact, it should be noted that the system is mechanically connected in such a way that as water fills the inner chamber, the force acting on the lower wall of the lower liner 16 increases, thereby pressing the wall of the lower liner against the upper flange 115 of the male gland and thereby strengthening the seal. Similarly, the male gland is similarly pressed against the interior of the housing wall 2 around its lower flange 118. In this way, as the water fills the tank and the pressure in the intermediate chamber between the diaphragm and the outer wall of the tank increases, the mechanical stresses acting on the gland and the walls of the two volumes increase, thereby increasing the bonding pressure between the surfaces and thus reducing the likelihood of any leakage between the two volumes.

Claims (8)

1. An expansion tank, the expansion tank comprising: A rigid outer shell and a bladder-like member disposed within the outer shell, wherein the bladder-like member includes a flexible first diaphragm having an outer peripheral edge and a second diaphragm having an outer peripheral edge, wherein the outer peripheral edges of the first and second diaphragms are sealed to each other to form a circumferential seam, and wherein an inner chamber defined by the bladder-like member is fluidly separated from an intermediate chamber between the bladder-like member and the outer shell of the expansion tank; and A convex sealing cap extends through a hole in the bottom of the second diaphragm to reach and pass through the lower wall of the rigid outer shell of the expansion tank. The convex sealing cap includes: an upper flange that is permanently sealed to the lower surface of the second diaphragm to form a tight seal that is completely fluidly sealed to both gas and liquid; and a lower extension that extends below the second diaphragm to extend through the outer rigid wall of the expansion tank to seal with the inlet pipe, thereby allowing liquid to flow into the inner chamber, which completely seals and separates the inner chamber from the intermediate chamber of the expansion tank, allowing the flexible first diaphragm to be pushed upward and outward into the intermediate chamber as water fills the inner chamber to pressurize the gas in the intermediate chamber. 2. The expansion tank according to claim 1, wherein the upper flange of the convex sealing cap and the lower surface of the second diaphragm are permanently sealed together by welding the upper flange of the convex sealing cap and the lower surface of the second diaphragm together, and the upper flange of the convex sealing cap and the lower surface of the second diaphragm are both formed of compatible thermoplastic materials. 3. The expansion tank of claim 1 further comprises an intermediate layer of a mutually compatible material between the upper flange of the convex sealing cap and the lower surface of the second diaphragm, so as to permanently seal the upper flange of the convex sealing cap to the lower surface of the second diaphragm by welding the mutually compatible material to both the upper flange of the convex sealing cap and the lower surface of the second diaphragm. 4. The expansion tank of claim 1 further includes an intermediate layer of mutually compatible material between the upper flange of the convex sealing cap and the lower surface of the second diaphragm, so as to permanently seal the upper flange of the convex sealing cap and the lower surface of the second diaphragm by bonding the two together. 5. The expansion tank according to claim 1, wherein the inlet pipe is sealed to the convex sealing cap via a central circumferential sealing member, so as to form a tight seal between the inlet pipe and the convex sealing cap. 6. The expansion tank according to claim 1, wherein the inlet pipe is sealed to the outer rigid wall of the expansion tank by welding, and both the inlet pipe and the outer rigid wall of the expansion tank are formed of compatible metals. 7. The expansion tank according to claim 1, wherein the second diaphragm is formed of a rigid polymer material. 8. The expansion tank according to claim 1, wherein the flexible first diaphragm is formed of a material selected from flexible thermoplastic materials and elastomeric polymers.