Double-wall underground container for storing liquids and leak detecting means therefor

Claim 2

A double-wall underground container for storing liquids, comprising a generally cylindrical reinforced plastic inner tank, a generally cylindrical reinforced plastic outer tank larger than and surrounding the inner tank in spaced relationship thereto, each of said tanks having a generally cylindrical wall portion and a pair of opposed end cap portions, a plurality of reinforced plastic annular connecting ribs spaced from each other axially of the tanks and connecting the cylindrical wall portions of the tanks to each other, annular chambers between the tanks being defined by the cylindrical wall portions of the tanks and pairs of adjacent connecting ribs, two opposed end chambers between the tanks being defined by the end cap portions of the tanks, and the connecting ribs having two sets of generally aligned passageways extending therethrough axially of the tanks, one set being disposed essentially at the tops of the tanks and another set being disposed essentially at the bottoms of the tanks, the passageways interconnecting all the annular chambers and the two end chambers.

Claim 3

An underground storage container as claimed in claim 1 wherein the inner and outer tanks are reinforced with chopped glass strands.

Claim 4

An underground storage container as claimed in claim 1 wherein the connecting ribs are reinforced with continuous glass filament windings.

Claim 5

A leak detecting system for an underground storage container as claimed in claim 1 comprising an aboveground reservoir, a conduit connecting the inside of said reservoir to the space between said tanks, leak detecting liquid filling the space between the tanks, filling the conduit, and at least partially filling the reservoir, means for sensing a drop in the level of the liquid in the reservoir, and means for providing a signal in response to a sensed drop in said level.

Claim 6

A double-wall container comprising a generally cylindrical inner tank, a generally cylindrical outer tank larger than and surrounding the inner tank in spaced relationship thereto, and a plurality of generally annular connecting ribs, said inner tank, outer tank, and connecting ribs comprising hardened hardenable liquid resin, each of said tanks having a generally cylindrical wall portion substantially concentric with that of the other about a common axis, the common axis being substantially horizontal in an installed position of the double-wall container, said connecting ribs being generally perpendicular to and surrounding said common axis, being substantially parallel to each other, being spaced from each other generally along said common axis, being disposed between and connecting the cylindrical wall portions of the tanks to each other, and together with the cylindrical wal portions defining annular chambers surrounding said common axis and respectively being disposed between pairs of adjacent ones of the ribs, and each of the connecting ribs disposed between a pair of adjacent ones of said annular chambers having passageway means therethrough interconnecting the respective pair of annular chambers.

Claim 7

A double-wall container comprising a generally cylindrical inner tank, a generally cylindrical outer tank larger than and surrounding the inner tank in spaced relationship thereto, and a plurality of generally annular connecting ribs, said inner tank, outer tank, and connecting ribs comprising hardened hardenable liquid resin, each of said tanks having a generally cylindrical wall portion substantially concentric with that of the other about a common axis, the common axis being substantially horizontal in an installed position of the double-wall container, said connecting ribs being generally perpendicular to and surrounding said common axis, being substantially parallel to each other, being spaced from each other generally along said common axis, being disposed between and connecting the cylindrical wall portions of the tanks to each other, and together with the cylindrical wal portions defining annular chambers surrounding said common axis and respectively being disposed between pairs of adjacent ones of the ribs, and each of the connecting ribs disposed between a pair of adjacent ones of said annular chambers having passageway means therethrough interconnecting the respective pair of annular chambers.

Claim 8

A double-wall container as claimed in claim 5 wherein the resin includes glass fiber reinforcing means.

Claim 9

A double-wall container as claimed in claim 5 wherein each of said tanks has a pair of opposed end cap portions respectively spaced from corresponding end cap portions of the other of said tanks and two end ribs respectively adjacent opposite ends of the cylindrical wall portions of the tanks have passageway means therethrough connecting the spaces between corresponding end cap portions at opposite ends of the tanks respectively to the adjacent annular chambers, the end cap portions comprising hardened hardenable liquid resin.

Claim 10

A double-wall container as claimed in claim 7 wherein the end caps include glass fiber reinforcing means.

Claim 11

A leak detecting system for a double-wall container as claimed in claim 7 comprising a reservoir above the container, a conduit connecting the inside of the reservoir to the space between said tanks, leak detecting liquid filling said annular chambers and the spaces between said end cap portions, filling the conduit, and at least partially filling the reservoir, means for sensing a drop in the level of the liquid in the reservoir, and means for providing a signal in response to a sensed drop in said liquid level.