Plastic tank for the storage and transport of bulk material

Abstract

The present invention relates to a plastic tank for the storage and transport of bulk materials, such as solids, liquids or semi-liquids, wherein said tank comprises a main body ( 1 ) with tapered sidewalls and a built-in pallet base ( 18 ) with four legs, a main rectangular lid ( 2 ), a secondary round lid ( 3 ) having a vent cap with a gas valve ( 4 ) and a bottom discharge opening ( 17 ). Said tanks are made of food grade HDPE of a special composition molded in one-piece using an injection molding process, and are nestable, when empty for shipment purposes and stackable, when full for storage purposes.

1 . A plastic tank for the storage and transport of bulk materials, such as solids, liquids or semi-liquids comprising:
 a) a main body ( 1 ) having a rectangular base ( 18 ) with integrally built-in at least four legs ( 20 ), four sidewalls ( 11   a ,  11   b ,  12   a ,  12   b ) extending in trapezoid shape upwardly and outwardly from the base ( 18 ), and defining a rectangular top opening, which forms a body-rim ( 15 ) provided with a projecting edge ( 16 ) along the periphery of the body-rim ( 15 ), wherein said base ( 18 ) with said at least four legs ( 20 ) have a pallet type configuration, the bottom surface of the base ( 18 ) is externally reinforced with base ribs ( 19 ) molded in both directions, and said four sidewalls ( 11   a ,  11   b ,  12   a ,  12   b ) are provided with webbed ribs ( 13 ) molded across their external surface so as to provide great strength and stability to the main body ( 1 );   b) a main rectangular lid ( 2 ) having a top surface, a bottom surface, an eccentric round opening ( 30 ) for filling up the tank and a main-lid rim ( 31 ) with a main-lid groove ( 14 ) along the periphery of said main rectangular lid ( 2 ) and a main-lid rubber gasket ( 71 ) that fits in said main-lid groove ( 14 ), wherein said main lid ( 2 ) is attached to the open top of the main body ( 1 ) and is closed with safety-lock pins ( 8 ) secured along the body-rim ( 15 ) of said main lid ( 2 ) and the main-lid rim ( 31 ) of the main rectangular lid ( 2 ), said safety-lock pins ( 8 ) in conjunction with the main-lid rubber gasket ( 71 ) provide a watertight sealing to the tank, the bottom surface of the main lid ( 2 ) comprises webbed ribs ( 36 ) molded in both directions so as to control internal forces when the tank is loaded, the top surface of the main lid ( 2 ) comprises feet sockets ( 27 ) molded on the four corners so as to receive the feet of the upper tank during stacking, and the round opening ( 30 ) is provided with a round lid groove ( 34 ) around the its periphery to hold a round-lid rubber gasket ( 72 ) around the periphery of the secondary round lid ( 3 ) for a watertight seal when closed; and   c) a secondary round lid ( 3 ) that fits in the eccentric round opening ( 30 ) of the main rectangular lid ( 2 ) comprising a vent hole ( 22 ) sealed with a vent cap with a gas extraction valve ( 4 ) to facilitate the outflow of the fermentation gases formed inside the tank, wherein said base ( 18 ) with the at least four legs ( 20 ) and the four sidewalls ( 11   a ,  11   b ,  12   a ,  12   b ) are made of plastic molded in one-piece, one of the sidewalls of the main body ( 1 ) adjacent to the base ( 18 ) of the main body ( 1 ) of the tank comprises a discharge opening ( 17 ) that can be equipped with a drainage valve ( 50 ) in order to empty the liquids inside the tank, and said at least four legs ( 20 ) of the base surface further comprise detachable and replaceable feet plugs ( 5 ) suitable to be plugged in said legs ( 20 ).   
     
     
         2 . The tank according to  claim 1 , wherein said four sidewalls ( 11   a , 11   b ,  12   a , 12   b ) are reinforced with differentially dimensioned ribs ( 13 ) webbed symmetrically across the external surface of the sidewalls forming a turtle-shell-like design, in order to transfer pressure and weight forces from the top surface of said main rectangular lid ( 2 ) to the base ( 18 ) of said main body ( 1 ), when stacked, making said tank robust and durable. 
     
     
         3 . The tank according to  claim 1 , wherein the at least four sidewalls at their corners are provided with particularly designed protruding corner-ribs ( 6 ), which extend from directly below the main body-rim ( 15 ) of the top opening, across its four corners, to the base ( 18 ), said protruding corner-ribs ( 6 ) providing the desired distance between the empty tanks, when nested to prevent jamming and minimize extraction effort. 
     
     
         4 . The tank according to  claim 2 , wherein the discharge opening ( 17 ) on the lowest part of the front sidewall ( 11   a ) of the main body ( 1 ) is provided with a corresponding internal filter ( 9 ) for the containment of solids. 
     
     
         5 . The tank according to  claim 1 , wherein said at least four legs ( 20 ) are shaped like caved pallet-feet so as to enable the use of a forklift on all four sides of the tank, and the detachable and replaceable feet plugs ( 5 ) are plugged in said legs ( 20 ) using specific safety feet-clips ( 21 ). 
     
     
         6 . The tank according to  claim 5 , wherein two traverses ( 10 ) can be clipped onto the legs ( 20 ) of the base ( 18 ), each traverse ( 10 ) comprises three feet plugs ( 5 ) on a traverse base ( 53 ), two feet plugs ( 5 ) to be plugged in the legs ( 20 ) of the base ( 18 ) and a third middle traverse foot plug ( 54 ) to be plugged into the base ( 18 ) and secured with a middle foot clip ( 55 ). 
     
     
         7 . The tank according to  claim 1 , wherein the bottom surface of the main rectangular lid ( 2 ) further comprises screen-ribs ( 37 ) that are elongated and differentially shaped than the webbed ribs ( 36 ). 
     
     
         8 . The tank according to  claim 1 , wherein the main rectangular lid ( 2 ) further comprises a rainwater drain-off hole ( 29 ), and the main-lid rim ( 31 ) comprises main-lid ribs ( 33 ) molded on its top surface, which provide rigidness and strength. 
     
     
         9 . The tank according to  claim 1 , wherein the secondary round lid ( 3 ) is manufactured from HDPE, comprising on its top surface six handles ( 40 ) with six security holes ( 41 ), its vent hole ( 22 ) comprises a vent-hole groove ( 42 ) wherein the vent-cap rubber gasket ( 73 ) is fitted, and six sealing ridges ( 23 ) on the bottom surface of the secondary round lid ( 3 ) secure it onto the main rectangular lid ( 2 ). 
     
     
         10 . The tank according to  claim 1 , wherein said tank further comprises a rectangular retaining screen ( 60 ) placed under the main rectangular lid ( 2 ), said screen ( 60 ) has an eccentric round opening ( 61 ) corresponding to the round opening ( 30 ) of the main lid ( 2 ), wherein a small round screen ( 70 ) is placed 
     
     
         11 . The tank according to  claim 1 , wherein the safety-lock pins ( 8 ) are manufactured of polyamide, and are inserted in key shaped holes ( 32 ) on the main-lid rim ( 31 ) of the main rectangular lid ( 2 ) and corresponding body-sockets ( 46 ) on the body-rim ( 15 ) of the main body ( 1 ). 
     
     
         12 . The tank according to  claim 5 , wherein said vent cap with gas extraction valve ( 4 ) comprises a gas valve cover ( 56 ) with a safety cover-hole ( 57 ) and an internal gas discharge valve ( 58 ) comprising a specific elastic membrane ( 26 ) which automatically moves upwards and opens so as to enable the discharge of fermentation gases. 
     
     
         13 . The tank according to  claim 1 , wherein the main-lid rubber gasket ( 71 ) fitted into the main-lid groove ( 14 ), the round-lid rubber gasket ( 72 ) fitted into the round-lid groove ( 34 ), and the vent-cap rubber gasket ( 73 ) fitted into the vent-cap groove ( 42 ) are all manufactured from food grade silicone material. 
     
     
         14 . The tank according to  claim 1 , wherein the vent cap with gas extraction valve ( 4 ) is made from food grade HDPE and its elastic membrane ( 26 ) is made from food grade silicone material. 
     
     
         15 . The tank according to  claim 1 , wherein the main body ( 1 ) of the plastic tank is manufactured from HDPE using a one-piece injection molding process. 
     
     
         16 . The tank according to  claim 1 , wherein the main rectangular lid ( 2 ) of the plastic tank is manufactured from HDPE using a one-piece injection molding process.