Receptacles – Stationary tank – For petroleum or a petroleum product
Reexamination Certificate
1994-09-30
2001-09-11
Pollard, Steven (Department: 3727)
Receptacles
Stationary tank
For petroleum or a petroleum product
C220S565000, C220S592200
Reexamination Certificate
active
06286707
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a container vault and, more particularly, to an above-ground storage tank for flammable liquids.
2. Discussion of Background
Since the 1970s, people in the United States as well as in other parts of the world, have become increasingly concerned with the environment and the contamination of that environment, including the earth's soil, its atmosphere, and its water. The first Earth Day in 1970 resulted in the eventual creation of the Environmental Protection Agency by the United States Congress.
One of the many problems which the Environmental Protection Agency has addressed in recent years is the deterioration of large, underground storage tanks which has resulted in the leakage of contaminants into the soil. For example, the deterioration of gas station storage tanks has resulted in the leakage of gasoline and diesel fuel into the surrounding water table.
To correct this problem, the EPA has suggested that all fuel storage tanks be placed above ground. However, this has created a classic confrontation between governmental departments, since the fire departments of most major cities prefer that fuel storage tanks be placed below ground to reduce fire hazard. Most municipal codes have been drafted with this concern in mind. In more recent years, the creation of large concrete-entombed tanks has been suggested as a solution to the problem. In accordance with this suggestion, a gasoline storage tank may be entombed in concrete and placed above the ground to enable its surfaces to be easily checked for deterioration and fluid leakage. By entombing the fuel tank in concrete, the tank was thought to be impervious to impact from a vehicle that might back into it, for example, and resistant to fire due to the insulating effect of the concrete. One example of such an entombed tank is shown in U.S. Pat. No. 4,826,644, issued May 2, 1989 to T. R. Lindquist and R. Bambacigno.
The concrete entombed tank has several disadvantages, however, including cost and convenience. For example, a 1,000-gallon concrete-entombed tank weighs 18,000 pounds after it has been manufactured, and such a tank requires a large truck and crane with at least two 20-ton nylon straps to transport it to the site where it is to be used and to then place the tank in the desired position. The concrete-entombed tank is provided with bottom supporting feet to permit the inspection of its bottom surface during its use. In California, where earthquakes represent a real concern, concrete shoes are placed on the site on either side of the bottom supporting feet to prevent the movement of the tank during an earthquake. The placement of the concrete tank between the concrete shoes can be a very dangerous procedure in view of the tank's weight.
Another disadvantage of the concrete-encased tank is that the exposed concrete is subjected to environmental effects, such as varying temperatures, which eventually lead to cracking and deterioration. Because of these problems, exposed concrete typically must incorporate heavy aggregate such as stone, increasing is weight and at the same time reducing its insulating qualities.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a less expensive, lighter weight and more easily transported container for the above-ground storage of liquid fuels, such as gasoline and diesel fuel.
It is another object of the invention to provide a protective vault for above-ground storage tanks, wherein the vault consists of an insulating material such as lightweight concrete encased in a steel protective shell to prevent deterioration of the insulating material while providing increased safety.
These and other objects are accomplished in accordance with one embodiment of the invention, by providing an inner tank having a bottom surface, side surfaces, and a top surface which is placed within an outer shell having a bottom surface, side surfaces, and an open top. The bottom surface of the inner tank is spaced apart from and connected to the bottom surface of the outer shell by first bottom spacers which do not extend to the side surfaces of either the inner tank or outer shell. The side surfaces of the inner tank and the outer shell are spaced apart and attached to one another by second side spacers which do not extend to the bottom surface of either the inner tank or outer shell. The spacers function to prevent the inner tank from floating within the outer shell when an insulating material, such as concrete, or more particularly a lightweight concrete, is placed in the space therebetween.
In other embodiments of the invention, the inner tank, the outer shell, or both may be cylindrical, with appropriate spacers or straps positioning and securing the inner tank within, and spaced from, the walls of the outer shell. The inner tank may be single or double walled, and may be made from any of a variety of materials, such as steel or other suitable metals, fiberglass, fiberglass-coated metal, polyethylene, or the like. The insulating material, which is located between the inner tank and the outer shell, cooperates with the steel outer shell to provide a protective vault for the inner storage tank, with the steel shell protecting the concrete, maintaining its integrity, and preventing deterioration due to weather, abuse, and ageing. The outer shell is supported on feet, and incorporates suitable inlets through which the insulating material is introduced into the space between the walls of the inner tank and the outer shell.
The construction of the protective vault which allows the use of a lightweight insulating material, permits the container to be constructed and filled with the insulating material at the factory, and transported to a location of use after completion. Alternatively, the utilization of an inner tank and outer shell, with appropriate spacers for locating one within the other, permits an assembled tank to be shipped from the factory to the site where it is intended for use before the concrete is added, so that the tank is moved with relative ease because of its even lighter weight. In the latter case, once the container is properly placed upon the site, the space between the inner tank and outer shell can be filled with a suitable insulation material to meet the strength and insulation requirements of the fire codes of all metropolitan areas. Spacing feet on the bottom surface of the outer shell permit all surfaces of the tank vault to be inspected to assure that the tank does not deteriorate and leak. As noted above, the outer shell is steel to allow the use of lightweight concrete while protecting the concrete from damage so it will retain its insulating value, thus providing a protective vault for the inner tank and thereby meeting the requirements of the Environmental Protection Agency.
In accordance with the present invention, the use of the lightweight insulating material disposed between a metal outer tank and an inner tank is particularly advantageous in that the lightweight insulating materials have superior insulating characteristics as compared with, for example, standard concrete. Although not to be construed as limiting upon the present invention, an example of a lightweight insulating material can be lightweight concrete having entrapped air therein. The entrapped air provides both greater insulating performance as well as a lighter weight construction, such that the insulating material need not be added at the installation site, since transport of the completed container is less burdensome than arrangements which utilize standard concrete. In accordance with a further advantageous aspect of the present invention, the feet which support the container can be formed of a metal such as steel, with an insulating material such as concrete or lightweight concrete disposed therein. The concrete or lightweight concrete within the feet maintains stability of the tank even when subjected to temperatures sufficient to weaken the steel outer casing of the feet. Suc
Hall William A.
Hall William Y.
Pollard Steven
Roth Gregory L.
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