Double wall liquid storage tank with sealing gasket and compression fitting

Abstract

A dual tank assembly is provided for storing agricultural and industrial liquids. The assembly includes an outer tank and an inner tank nested within the outer tank. The outer tank has an upper shelf and the inner tank has a rim overlying the shelf with a leaf gasket therebetween to seal the space between the shelf and the rim. The outer tank includes a recessed flat wall adjacent the bottom of the tank to mate with a flat wall in the inner tank. A compression fitting is tightened to sandwich a gasket between the flat wall portions of the inner and outer tanks. A drain fitting extends through the flat portions of the tank for draining liquid from the inner tank. A separate drain plug is provided for draining liquid from the outer tank.

What is claimed is: 
     
         1 . A dual tank assembly for storing liquids, comprising:
 an outer tank;   an inner tank nested within the outer tank;   the outer tank having an upper shelf;   the inner tank having a rim overlapping the shelf with a gap therebetween; and   a flexible leaf gasket residing between the shelf and the rim to seal the gap.   
     
     
         2 . The dual tank assembly of  claim 1  wherein the leaf gasket is mounted on the shelf. 
     
     
         3 . The dual tank assembly of  claim 1  wherein the leaf gasket extends angularly in the gap. 
     
     
         4 . The dual tank assembly of  claim 1  wherein the leaf gasket extends upwardly and outwardly from the shelf. 
     
     
         5 . The dual tank assembly of  claim 1  wherein the inner the inner and outer tanks each have cylindrical sidewalls which are spaced apart from one another. 
     
     
         6 . The dual tank assembly of  claim 1  wherein the outer tank has a bottom, a sidewall, and an inwardly extending upper lip, with the lip forming the shelf. 
     
     
         7 . The dual tank assembly of  claim 6  wherein leaf gasket is mounted on the lip. 
     
     
         8 . The dual tank assembly of  claim 1  wherein the inner tank has a bottom, a sidewall, and a top cover, with the rim extending between the top cover and the sidewall. 
     
     
         9 . The dual tank assembly of  claim 8  wherein the rim is sloped. 
     
     
         10 . The dual tank assembly of  claim 1  wherein the leaf gasket has a channel for mounting to the shelf. 
     
     
         11 . A dual tank assembly for storing liquids, comprising:
 an outer tank having a bottom, a sidewall, and an open top;   an inner tank nested within the outer tank, and having a bottom, a sidewall, and a top cover;   a containment space between the sidewalls of the tanks;   a recess in the sidewall of the outer tank, the recess residing adjacent the sidewall of the inner tank;   a fitting extending through the recess and through the inner tank sidewall for draining liquid from the inner tank.   
     
     
         12 . The dual tank assembly of  claim 11  wherein the fitting includes an inner ring on the inside of the inner tank and an outer ring on the outside of the recess, the rings being fastened together. 
     
     
         13 . The dual tank assembly of  claim 12  wherein the rings are compressed together by a plurality of fasteners. 
     
     
         14 . The dual tank assembly of  claim 12  herein the fitting includes a gasket residing between the inner ring and the inside of the inner tank. 
     
     
         15 . The dual tank assembly of  claim 12  wherein the fitting includes a gasket residing between the recess and the inner tank sidewall. 
     
     
         16 . The dual tank assembly of  claim 12  wherein the fitting includes a first gasket between the inner ring and the inside of the inner tank and a second gasket between the recess and the sidewall of the inner tank. 
     
     
         17 . The dual tank assembly of  claim 12  wherein the fitting includes a drain conduit extending through the rings. 
     
     
         18 . The dual tank assembly of  claim 11  further comprising a drain plug in the outer tank adjacent the bottom. 
     
     
         19 . The dual tank assembly of  claim 11  wherein the fitting is mounted on the tanks under compression so as to pull the recess and inner tank sidewall toward one another. 
     
     
         20 . The dual tank assembly of  claim 19  wherein the compression is provided by threaded fasteners, each extending through the fitting and through the inner and outer tanks. 
     
     
         21 . The dual tank assembly of  claim 11  wherein the recess has a planar back wall and the inner tank has a planar area on the sidewall aligned with the recess back wall, and through which the fitting extends. 
     
     
         22 . The dual tank assembly of  claim 11  wherein the recess and the inner tank each have flat areas aligned and compressed together by the fitting.