Patent Application
20090152271
This invention relates to a drum cover and, more particularly, to a cover for a high pressure drum.
In one form of conventional shipping and storage container, a drum comprises a tubular container having an open end with a cylindrical connecting bead at the open end. The connecting bead may be provided by a metal connecting ring rolled onto the side wall or a plastic connecting ring molded directly to or otherwise adhered to the side wall. Alternatively, the side wall may be of molded plastic construction with an integral connecting bead.
The conventional drum includes a removable cover for closing the open end of the tubular side wall. A typical cover includes a central circular wall with a peripheral connecting flange receivable on the connecting bead so that the circular wall closes the open end of the container. A locking band secures the cover on the drum. While such a container may be used for storage purposes, often the containers must be lifted by lifting equipment. Advantageously, the drum should be designed to accommodate parrot beak drum lifting devices. If the cover is not of sufficient thickness, the drum may not pass a typical parrot beak test. Typically, such a cover includes circular channels or rings formed in the circular wall providing a corrugated or wave-like appearance.
When used in shipping applications, the containers are often designed to meet certain requirements. These requirements may comprise drop ratings, pressure ratings or the like. One such rating is a liquid U.N rating for Z1.2/50/S/USA/GBC. In this rating, the 1.2 refers to the specific gravity of the contents of the container. The numeral 50 refers to the kPA rating of the container. With such a rating, a container, such as a drum and cover, must be capable of passing a hydro test in which the contents of the drum is filled with pressurized water. A conventional drum cover when subjected to a hydro test might fail as the pressure causes expansion of the cover which may lift the peripheral connecting flange away from the connecting bead.
The present invention is directed to solving one or more of the problems discussed above in a novel and simple manner.
In accordance with the invention, there is provided a cover for use with a tubular container for satisfying high pressure requirements.
Broadly, in accordance with one aspect of the invention, there is disclosed a unitary cover for use with a tubular container having an open end with a cylindrical connecting bead at the open end. The unitary cover comprises a central circular wall. A concentric ring region surrounds the central circular wall. An annular flange comprises a downwardly opening U-shaped channel receivable on the cylindrical connecting bead. A cylindrical connecting wall connects an inner edge of the annular flange, inwardly of the U-shaped channel, to the connecting ring region.
It is a feature of the invention that the annular flange and the connecting wall have a greater wall thickness than the circular wall and the concentric ring region.
It is another feature of the invention that the concentric ring region comprises first and second concentric rings disposed between the connecting wall and the central circular wall to define a generally corrugated structure.
It is another feature of the invention that the concentric ring region is connected at a central portion of the connecting wall.
It is still another feature of the invention that the connecting wall extends downwardly from the concentric ring region to back up the drum open end.
There is disclosed in accordance with another aspect of the invention, a unitary cover for use with a tubular container having an open end with a cylindrical connecting bead at the open end. The unitary cover comprises a central circular wall. An expansion region surrounds the central circular wall. An annular flange has three concentric cylindrical walls defining an E-shaped wall. An outermost and middle cylindrical walls define a channel receivable on the cylindrical connecting bead. An innermost cylindrical wall defines a hinge and is connected to the expansion region.
It is a feature of the invention that the annular flange has a greater wall thickness than the circular wall and the expansion region.
It is another feature of the invention that the expansion region comprises first and second concentric rings disposed between the annular flange and the central circular wall to define a generally corrugated structure.
It is still another feature of the invention that the expansion region is connected at a central portion of the innermost cylindrical wall.
It is still another feature of the invention that the innermost cylindrical wall further comprises a downwardly extending backup wall extending downwardly from the expansion region to back up a drum open end.
It is yet another feature of the invention to provide a pair of bung openings in the central circular wall.
It is yet another feature of the invention that the annular flange is a diameter to be received on a tubular container having a connecting bead in the range of 14″ to 23″.
It is still another feature of the invention that the cover comprises a unitary wall element of synthetic resin.
Further features and advantages of the invention will be readily apparent from the specification and from the drawings.
In the illustrated embodiment of the invention, as disclosed in
In the illustrated embodiment of the invention, the drum 12 comprises a cylindrical, blow-molded plastic drum. The drum has a capacity of 35 U.S. gallons and the connecting bead 20 has a diameter of about 18″. As is apparent, the dimensions of the drum 12 may vary and other typical dimensions of the connecting bead 20 are about 21-½″ and 23″. Typically, for a container of the type described herein, the diameter is in the range of 14″ to 23″. The present invention is directed particularly to the cover 22 which can be used with drums of other construction, such as metal, fiberboard, or composite construction, as will be apparent.
Referring to
Referring also to
An annular peripheral flange 60 is radially outwardly of the expansion region 34. The peripheral flange 60 comprises an upper annular wall 62 connected to three downwardly extending concentric cylindrical walls 64, 66 and 68. As such, the peripheral flange 60 is “E-shaped” in cross-section. The outermost cylindrical wall 64 and the middle cylindrical wall 66 define a downwardly opening U-shaped channel 68 for receiving the connecting bead 20. A gasket 70 in the channel 68 provides a seal between the cover 22 and the drum 12. The innermost cylindrical wall 68 is connected to a downwardly extending backup wall 72 at a bend 74. The second concentric ring shorter side 52 connects to the backup wall 72 at a generally mid-portion thereof, just below the bend 74. As such, the innermost cylindrical wall 68 and the backup wall 72 define a connecting wall connecting the expansion region 34 to the peripheral flange 60.
As described, when the cover 22 is mounted to the drum 14, the connecting bead 20 is received in the channel 68. The connecting bead 20 extends upwardly from a flange 76 extending outwardly from the drum tubular side wall 14. The locking band 24 sandwiches the peripheral flange 60, gasket 70 and connecting bead 20 to retain the cover 22 on the drum 12 in a conventional manner.
In accordance with the invention, the container 12 including the cover 22, comprising a high pressure cover, satisfies requirements of UN rating Z1.2/50/S/USA/GBC. The expansion region 34 allows expansion of the cover 22 if it is subjected to a drop test. The resulting impact of product on the cover 22 pushes on the cover rather than breaking. Additionally, with a hydro test, the space 18 is filled with pressurized water. The concentric rings 36 and 38 expand to take the resulting force. Additionally, the cover 22 is adapted to hinge at the peripheral flange innermost cylindrical wall 68 where it meets the annular wall 62, at an area noted H. This moves the hinged point away from the contact surface between the gasket 70 and the connecting bead 20 allowing the gasket 70 to remain in full contact with the connecting bead 20 under high pressure conditions. The connection of the second concentric ring 38 to the backup wall 72 must be sufficiently below the hinge point H so that when expansion of the rings 36 and 38 occurs due to hydrostatic pressure, the circular panel 28 pulls on the backup wall 72 to allow the hinging to function properly.
Additionally, the wall thickness of the expansion region 34 is less than that of the peripheral flange 60. This is intended to allow the expansion region 34 to react to pressure changes as needed.
Thus, in accordance with the invention, there is provided a unitary cover including reduced wall thickness in non-critical areas to reduce weight.
