Receptacles – End wall structure – Having an outlet or inlet opening
Reexamination Certificate
2000-04-12
2001-03-27
Pollard, Steven (Department: 3727)
Receptacles
End wall structure
Having an outlet or inlet opening
C220S001500, C220S004130
Reexamination Certificate
active
06206228
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a double-walled tank for storing fluids such as heating oil, diesel fuel, and lubricating and hydraulic oils, with an inside container made of plastic, and an outside container made of sheet steel. In the invention, the outside container is provided with a container cover having openings for receiving sockets of the inside container. The inside container is a plastic container, preferably produced by blow molding. The outside container has a mechanical protective function and, furthermore, protects against leakage if the inside container should leak.
The outside container has, for example, a container jacket consisting of a U-shaped jacket sheet forming the container bottom and two side walls, as well as two end sheets joined with the jacket sheet. The end sheets and the jacket sheet are connected either by welding, or by a flange joint along the longitudinal edges. However, the outside container may also consist of a bottom sheet and a single or multi-part jacket shaped in the form of a “U”, whereby the bottom sheet and the jacket can be tightly flanged or welded together (See German patent DE-OS 1 960 889).
2. The Prior Art
In practice, the cover of the outer container is screwed or riveted to the container jacket, or retained on the latter by means of spring clamps. The openings that pass through the sockets or threaded pipes of the inside container are provided with a blind ring for visual correction, and prevent rain water from penetrating the openings. However, there is no gas or liquid tight encapsulation of the jacket space between the inside and outside container. The tanks with the design known from prior art practical applications can be combined in assemblies of up to 25 units, and set up for storing heating oil without a brickwork tub for quantities of up to 25 cubic meters at the most. In furnace rooms, the stored quantity may not exceed 5 cubic meters. In water protected areas and in locations where old oils are stored, the tanks must always be set up in a brickwork tub that is sealed by a suitable protective paint coating. For leakage monitoring, provision is made for a leakage sensor located between the inside and the outside containers, which is installed in the container cover (See German patent DE 196 37 868 C1).
SUMMARY OF THE INVENTION
The present invention provides an apparatus for reducing the risk of emissions for double-walled tanks in the event the inside container leaks, so that the tanks can be installed without a bottom tub under critical installation conditions. The invention thus provides a container cover that has a collar with a U-shaped cross section. The collar is mounted on the top edge of the container jacket and solidly joined with the latter. Moreover, the interior space of the collar contains a seal, to seal the collar gas-tight against the container jacket. Furthermore, pressure rings in the form of ring seals on thrust rings are arranged on the sockets or threaded pipes for applying pressure to the seals surrounding the sockets.
According to the invention, the jacket space between the inside container consisting of plastic, and the outside container produced from sheet steel, is encapsulated with liquid and is substantially gas-tight. The sheet steel elements of the outside container are preferably connected to each other in a form locked or closed way, and free of penetration. Galvanized, powder-coated or lacquered steel sheets can be used. Good protection against corrosion is assured because of the penetration-free connection technique.
According to a preferred embodiment of the invention, the outside container has both a U-shaped container jacket consisting of a jacket sheet forming the container bottom and two side walls, and two end sheets connected with the jacket sheet. The jacket sheet and the end sheets can be joined by welding the parts together. However, the sheets are preferably connected to each other by flanging them together. A seal is inserted in the flange connection, extending up to the top edge of the container jacket. The edges of the flanges flatly abut the container cover within the area of connection, and engage the collar of the container cover.
The collar of the container cover preferably contains a permanently elastic sealing compound. As an alternative, it is also possible to insert cord or strip-shaped seals, the latter assuring uninterrupted sealing between the container cover on the one hand, and the container jacket on the other.
According to a preferred embodiment of the invention, the leg of the container collar abutting the inner side of the container jacket is wider than the section of the collar abutting the outer side of the container jacket. Moreover, the container jacket is connected with the leg of the collar located on the inner side of the container by means of identical, perforation-free deformations of the steel sheets. The edge enveloping the container jacket on the outer side is preferably folded over toward the container jacket in the form of a flanged edge to protect the seal and to eliminate any possible risk of injury.
The seals associated with the sockets can be disposed between the container cover and the inside container, or may extend around the edges of the holes in the container cover in a U-shaped form. The sockets are preferably threaded sockets to receive corresponding threaded thrust rings.
According to another embodiment of the invention, a device for monitoring leakage is connected to the jacket space between the inside and outside containers. The device is connected to a vacuum pump, and has a suction line extending into the lower zone of the jacket space, as well as a measuring line for measuring the pressure. In the event that the inside or outside container leaks, the vacuum collapses, and the leakage is indicated visually and/or acoustically. The blow-molded plastic inside container has only low dimensional stability, so that the static pressure of the stored fluid and the vacuum prevailing in the jacket space may cause the inside container to be forced against the surface of the wall of the outside container. In order to assure that the entire jacket space is reliably monitored for leakage, a layer permeable to gas is disposed between the inside container and the outside container to prevent the inside container from flatly abutting the jacket of the outside container. The same effect can be obtained if the outer surface of the inside container has a surface structure consisting of point-like dimple projections, or line-shaped elevations or ridges.
If the double-walled tank is set up in areas where flooding may occur, it is necessary to prevent the tank, from floating upward when acted upon by the buoyant force of water. According to the invention, the tank can be secured against floating by affixing claws to the container cover in the corner areas, which are clamped against the container cover by means of tension rods anchored in the floor of the storage facility.
REFERENCES:
patent: 3437231 (1969-04-01), Carpenter, Jr.
patent: 4157609 (1979-06-01), Schutz
patent: 4173288 (1979-11-01), Schutz
patent: 4648521 (1987-03-01), Thomas et al.
patent: 4917246 (1990-04-01), Edelhoff
patent: 5201437 (1993-04-01), Burgdorf
patent: 5480057 (1996-01-01), Papaluca
patent: 1 960 889 (1971-06-01), None
patent: 196 37 868 (1997-11-01), None
Collard & Roe P.C.
Pollard Steven
Roth Werke GmbH
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