Fluent material handling – with receiver or receiver coacting mea – With soil removing – coating – lubricating – sterilizing and/or... – Drip collection
Reexamination Certificate
2000-06-14
2001-06-26
Douglas, Steven O. (Department: 3751)
Fluent material handling, with receiver or receiver coacting mea
With soil removing, coating, lubricating, sterilizing and/or...
Drip collection
C141S088000, C141S31100A, C222S108000, C220S004120, C220S495040
Reexamination Certificate
active
06250345
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to above-ground storage systems for liquids and, more particularly, to a storage system having a secondary containment dike and an overflow drain within the primary tank to divert fluid to the secondary containment dike.
BACKGROUND OF THE INVENTION
In accordance with EPA regulations, an above-ground storage tank system for containing fuels, potentially hazardous fluids, or any other liquids that would create environmental problems if released into the ground must include a secondary containment device capable of storing at least 110% of the fluid that can be contained in the storage tank. The secondary containment device is typically comprised of a dike that at least partially surrounds the tank to prevent ground contamination that may occur from leaks and overfills.
Several containment system designs are known for storing fluid that was spilled or overfilled from an internal storage tank. U.S. Pat. No. 5,203,386 (“the '386 patent”) discloses a storage system in which a secondary container having an attached hood completely surrounds an internal storage tank. The hood over the dike prevents rain or ambient precipitation and trash from entering the dike. As shown in
FIGS. 1 and 2
herein, which correspond with FIGS. 1 and 2 of the '386 patent, the internal storage tank is filled by opening a door
10
on housing
12
formed at the top of the structure to gain access to one of the internal tank ports
20
,
22
,
24
. The housing
12
is located above input ports but is not connected to the internal tank. If fluid leaks from one of the ports or is spilled within the housing
12
, it runs along the exterior of the internal tank
14
, within the sloping side walls
16
of hood
18
, and into the dike
26
.
U.S. Pat. No. 4,895,272 (“the '272 patent”) describes another liquid storage system having a roof structure that extends from a point along the upper side of the internal storage tank to the sides of the dike. As shown in
FIGS. 3-4
, drainage structure
40
is a passageway that extends from the side of housing
38
, through the roof structure
34
, and into storage space
42
in the external containment vessel
32
. If liquid is spilled or is overflowing from the internal tank, it runs within the passageway
46
and along the exterior of the internal storage tank.
In many applications that require an above-ground storage tank apparatus, it would be advantageous to recover any spilled or overflowing fluid for use. However, this is not possible with the liquid storage system described in the '272 patent, because the roof structure does not provide a liquid-tight seal to prevent spilled liquid from contamination. In most circumstances, spilled liquid cannot be re-used if it contacts with water in the external containment vessel
32
, and it then must be disposed as a hazardous material. As for the containment system described in the '386 patent, it is difficult for an operator to detect whether any fluid has leaked from an input port, because there is no bottom portion to the housing
28
to collect the spilled fluid.
Even if the spilled liquid does not become contaminated in the systems disclosed in the '272 and '386 patents, it must be drained or pumped from the dikes. The interior of the dike must then be cleaned, which can be a difficult and time-consuming process. On most occasions, only a small quantity of fluid leaks from an input port of the internal storage tank. Accordingly, there is a need for an above-ground storage tank apparatus that overcomes the problems of contamination and the labor-intensive process required for recovering fluid when only a small portion of fluid leaks from an input port of the internal tank.
For some applications, it is also advantageous to pressure test the storage space between external containment vessel and the internal storage tank. Pressure testing assures that the external containment area is properly sealed such that any spilled fluid does not become contaminated. However, the containment systems described in both the '272 and the '386 patents do not readily allow an operator to conduct pressure testing. Accordingly, there is also a need for a storage tank apparatus that provides for pressure testing.
SUMMARY OF THE INVENTION
The present invention provides a secondary containment and drainage system for an above-ground storage tank in which small quantities of leaked or overflowing liquid are temporarily stored in the housing above the internal storage tank. This fluid can be easily removed from the housing for re-use or at least removed without the time consuming process of emptying and cleaning the dike. When greater quantities of liquid leak from the input port of the storage tank, the overflowing liquid is drained into the dike through a drainage pipe that extends through the internal storage tank and protrudes into the housing. The drainage pipe empties into the dike that is beneath and surrounding the internal storage tank. The drainage pipe is positioned to allow a certain quantity of liquid to remain in the housing, but prevents any liquid from overflowing out of the housing of the storage system.
The housing on top of the storage tank and all vents are attached to a plate. The plate is attached to a roof structure, which extends to the top of the walls of the dike. The plate and roof structure are attached, preferably by welding, to form a liquid-tight seal. This provides containment completely surrounding the internal storage tank to prevent contamination.
An object of the present invention is to provide an above-ground storage tank apparatus comprising an internal storage tank for storing liquid injected through an input port protruding therefrom, a secondary containment vessel surrounding the internal storage tank, a drain pipe extending through and protruding from the internal storage tank at a first and second location, and a spill box connected to the internal storage tank and surrounding the input port and the drain pipe protruding from the internal storage tank. The spill box stores a first quantity of liquid that is spilled during injection into the internal storage tank, and amounts of liquid greater than the first quantity of liquid are drained from the spill box through the drain pipe and into a containment area between the secondary containment vessel and the internal storage tank.
A further object of the invention is to provide an above-ground containment system having a sealed secondary containment area. The system includes an internal storage tank for storing liquid injected through an input port protruding therefrom, a secondary containment vessel surrounding the internal storage tank for storing liquid spilled from the input port, a drain pipe extending through and protruding from the internal storage tank at a first location near the input port and a second location in a secondary containment area between the internal storage tank and the secondary containment vessel, a spill box connected to the internal storage tank and surrounding the input port, and a roofing structure extending from sides of the spill box to walls of the secondary containment vessel to seal the secondary containment area. The seal of the containment system can be pressure tested by applying pressure through the drain pipe at the first location.
REFERENCES:
patent: 4815621 (1989-03-01), Bartis
patent: 4895272 (1990-01-01), De Benedittis et al.
patent: 5058633 (1991-10-01), Sharp
patent: 5197627 (1993-03-01), Disabato et al.
patent: 5203386 (1993-04-01), Harp
patent: 5346093 (1994-09-01), De Benedittis et al.
patent: 5381923 (1995-01-01), O'Dea
patent: 5538052 (1996-07-01), Harp
patent: 5564588 (1996-10-01), Reese
patent: 5570714 (1996-11-01), Magish
patent: 5702026 (1997-12-01), Lindquist
patent: 5769109 (1998-06-01), Stanton et al.
patent: 5884709 (1999-03-01), Evans et al.
patent: 6039123 (2000-03-01), Webb
Allwein Steven P.
Macy Stephen C.
Containment Solutions, Inc.
Douglas Steven O.
Pittman Shaw
LandOfFree
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