Abstract:
A common metal drum is used in an upside down orientation and has a drum liner system installed through the designated bottom surface thereof. The drum liner system comprises an adapter mounted through the designated bottom surface. The adapter has a relatively large opening through which the liner is easily installed and the drum can be easily inspected and repaired. In another aspect, the adapter and a liner collar share a common thread, and a cover is mountable over this common thread. The thread portion on the liner collar is selectively movable relative to the thread portion on the adapter to cause a locknut effect therebetween and to retain the cover on the adapter and the liner collar. In a further aspect, a drum liner is bonded to the liner collar and is folded inside the liner collar. A hermetic wrapper is stretched around the liner collar and the drum liner. This drum liner package is particularly advantageous for being shippable to a user in an aseptic condition and for being maintainable in this condition prior to use.

Description:
FIELD OF THE INVENTION 
     The present invention relates to drum liners and more specifically the present invention relates to drum liners that are mountable is common metal drums and that are washable and shippable to users in an aseptic condition and reusable. 
     BACKGROUND OF THE INVENTION 
     Drum liners are used primarily to prevent product contamination in metal drums and other barrels containing products that are sensitive to deterioration. Drum liners are also installed in re-used metal drums to extend the useful life of the drum. Although several designs of drum liners exist in the art, it is believed that some specific requirements of the industry have not been properly addressed in the past by prior designs. 
     One specific example of a very demanding industry with regard to container-related product contamination is the transportation of maple syrup. Maple syrups are recognized by their respective flavour which is relatable by the experts, to the location of a maple grove and to the setting and maple species within that maple grove. Maple syrups are very sensitive to taste deterioration, and the simple contact of the product with an improperly painted metal surface for example, or with the lightly corroded metal of a container can deteriorate its flavour beyond usability. Plastic liners have been used in the past inside metal drums and common plastic barrels for storing and transporting maple products. However, there remain some concerns with these liners. For example, the syrup is known to adhere to the interior of the liner, and because of the structural arrangement of these liners, recovery can hardly be made. When a purchased batch of syrup is contained in several barrels, the lost of syrup remaining in the empty liners can be substantial. 
     Another concern with liners of the prior art is that generally, metal drums have bung holes of relatively small size through which some liners are installed. The relatively small sizes of theses bung holes represent certain limitations in the installation of a liner. These limitations are known to compromise the cleanliness and impermeability of a new liner during its installation inside a barrel. 
     Examples of prior art plastic liners for use in metal drums and plastic barrels are illustrated in the following patent applications and issued U.S. patents. 
     AU-B-15,127 filed by R. M. Matyja, and published Oct. 29, 1992; 
     CA 2,061,161 filed by W. Lima et al., and published on Aug. 15, 1992; 
     GB 2,228,725 filed by G. K. Bunschoten, and published on Sep. 5, 1990; 
     U.S. Pat. No. 3,918,605 issued on Nov. 11, 1975 to C. J. Butler; 
     U.S. Pat. No. 4,094,432 issued on Jun. 13, 1978 to S. Zilbert; 
     U.S. Pat. No. 5,046,634 issued on Sep. 10, 1991 to G. P. McFarlin et al.; 
     U.S. Pat. No. 5,154,307 issued on Oct. 13, 1992 to T. W. Hauk; 
     U.S. Pat. No. 5,154,308 issued on Oct. 13, 1992 to D. A. Larson; 
     U.S. Pat. No. 5,169,019 issued on Dec. 8, 1992 to B. Büdenbender; 
     U.S. Pat. No. 5,217,138 issued on Jun. 8, 1993 to D. E. Nichols; 
     U.S. Pat. No. 5,222,620 issued on Jun. 29, 1993 to W. Lima et al.; 
     U.S. Pat. No. 5,379,913 issued on Jan. 10, 1995 to T. M. Rieke et al.; 
     Because of the aforesaid concerns, basically, it is believed that there continues to be a need in the industry for a drum liner system which is mountable in a common metal drum, which allows for a sanitary installation of the liner therein and from which adhered product can be easily washed out and recovered. 
     SUMMARY OF THE INVENTION 
     The present invention provides for a drum liner system which has a large opening, a holed flange associated therewith for easy installation in a steel drum&#39;s end surface, and through which the drum can be easily cleaned and reconditioned. The liner is shippable to a user in an aseptic package. After use, the liner can be pulled inside-out through the large opening for washing adhered product therefrom. When the adhered product is maple syrup, the rinse water is evaporated to recover the syrup. 
     Broadly, in accordance with a first aspect of the present invention there is provided a common metal drum having a drum liner system mounted therein. The common metal drum has a designated top and bottom surfaces. The drum is used in an upside down position and the drum liner system is installed through the designated bottom surface. 
     The drum liner system comprises an adapter mounted through an opening in the designated bottom surface of the drum, and having a flange connected to the designated bottom surface. An annular channel is bordering the flange and extends inside the opening. A liner collar is mounted over the adapter and has a sleeve portion extending inside the annular channel. A drum liner is bonded to the sleeve and extends inside the drum. The liner support system also includes a cover which is attachable to the adapter for covering the liner collar and the drum liner. 
     In this installation, the liner support surface is generally in a better condition than the opposite end of the drum. Because this designated bottom surface is generally free from any fittings, the opening and the adapter can have a relatively large size through which the drum can be easily inspected, repaired and reused several times for storing and transporting sensitive products. Also, the bung hole and vent plug in the designated top surface of the drum are usable as drain holes for assisting in the reconditioning of the drum. 
     In accordance with another aspect of the present invention, there is provided a drum liner system for installation in a metal drum or plastic barrel. This drum liner system comprises an adapter which is mountable in an opening in an end of a drum. The adapter has an annular flange and an annular channel bordering the annular flange and extending through a plane defined by the annular flange. The annular channel has a first external thread on a surface thereof. The drum liner system also comprises a liner collar mounted over the adapter and having a sleeve extending inside the annular channel. The liner collar has a second external thread on a surface thereof, and the second external thread is similar to and continuous with the first external thread on the adapter. The liner support system also comprises a drum liner bonded to the sleeve and a cover covering the liner collar and the liner. The cover has an internal thread on one of its surfaces and this internal thread has a similar shape and pitch as the first and second external threads, and is engaged over the first and second external threads. 
     The liner collar and the adapter are selectively positional relative to each other to wedge the first and second external threads against each other inside the internal thread to secure the cover on the adapter and on the liner collar. This locking action of the first and second external threads is advantageous for preventing inadvertent loosening of the cover during handling and transport of a drum having the liner support system mounted thereon. 
     In a further aspect of the present invention, there is provided drum liner package for installation in a drum having an appropriate drum liner adapter mounted thereon. This drum liner package comprises a liner collar having an inside diameter and a depth perpendicular to the inside diameter. A drum liner is bonded to the liner collar, and is folded inside the liner collar. A hermetic wrapper is stretched around the liner collar and the drum liner. This drum liner package is particularly advantageous for being shippable to a user in an aseptic condition, and for being maintainable in this condition prior to use. 
     Still other features of the invention are that it is susceptible of a low cost of manufacture with regard to materials, equipment and labour, and which accordingly is then susceptible of low price of sale to the industry, thereby making such liner support system economically available to the public. 
     Other advantages and novel features of the invention will become apparent from the following detailed description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A preferred embodiment of the present invention selected by way of example will now be described with reference to the accompanying drawings in which: 
     FIG. 1 illustrates a common metal drum having a drum liner system according to the preferred embodiment mounted therein; 
     FIG. 2 is a vertical cross-section view through the drum illustrated in FIG. 1; 
     FIG. 3 is a partial exploded side view of the drum liner system according to the preferred embodiment; 
     FIG. 4 illustrates a top view of the cover used in the drum liner system according to the preferred embodiment; 
     FIG. 5 is a cross-section view of the cover illustrated in FIG. 4, as seen along line  5 — 5  in FIG. 4; 
     FIG. 6 illustrates a top view of the adapter used in the drum liner system according to the preferred embodiment; 
     FIG. 7 is a cross-section view of the adapter illustrated in FIG. 6, as seen along line  7 — 7  in FIG. 6; 
     FIG. 8 is an enlarged partial top view of the adapter showing internal notches therein, as seen in detail circle  8  in FIG. 6; 
     FIG. 9 is a top view of the liner collar used in the drum liner system according to the preferred embodiment; 
     FIG. 10 is a partial side view of the liner collar shown in FIG. 9, illustrated with one segment cut out to show cross-section details. 
     FIG. 11 is a bottom view of the liner collar shown in FIGS. 9 and 10; 
     FIG. 12 is a cross-section view of the liner collar as seen along line  12 — 12  in FIG.10; 
     FIG. 13 is a side view of the liner and liner collar wherein the liner is shown as being turned inside-out for washing adhered product therefrom for example; 
     FIG. 14 is a partial cross-section view of the adapter with the liner collar mounted therein; 
     FIG. 15 is a partial cross section view of the drum liner system according to the preferred embodiment, taken across the rim of the adapter; 
     FIG. 16 is a perspective view of a wrapped liner and liner collar in a preferred packaging arrangement for shipment to a user; 
     FIG. 17 is a partial cross-section view of the adapter, in an alternate use for retaining a collar-less liner, taken across the rim of the adapter; 
     FIG. 18 is an enlarged partial cross-section view of the adapter and the cover in the alternate use for retaining a collar-less liner, taken across the rim of the adapter. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     While this invention is susceptible of embodiments in many various forms, there is shown in the drawings and will be described in details herein a specific embodiment, with the understanding that the present disclosure is to be considered as an example of the principles of the invention and is not intended to limit the invention to the embodiment illustrated. 
     Referring firstly to FIGS. 1,  2  and  3 , the drum liner system  20  according to the preferred embodiment comprises a plastic liner  22  and a liner collar  24  bonded to and circling the opening of the liner  22 . The drum liner system also comprises an adapter  26  for supporting the collar  24 , and a cover  28  which is mountable over the liner collar  24  and the adapter  26  for retaining the liner collar  24  in to the adapter  26  and for sealing the liner  22 . The dimensions of the liner collar  24 , the adapter  26  and the cover  28  are selected to provide sliding fit tolerances therebetween except where indicated otherwise, to afford mutual assembly and disassembly by hand. The material of construction of the liner  22 , the liner collar  24 , the adapter  26  and the cover  28  is preferably a food-approved grade of plastic. The liner  22  preferably has a thickness of about 4-6 mils or more. 
     The drum liner system  20  is preferably installed on a common metal drum  30  through the bottom surface  32  of the drum. The metal drum is thereafter used in the upside down orientation. A first reason for doing this is that the bottom surface  32  of a metal drum is generally in a better condition than the top surface with regard to corrosion after extended use. The second reason being that the top surface  34  of a metal drum contains a bung hole  36  and a vent plug  38 , the spacing of which relative to each other or to the rim of the drum represents a restriction in the diameter and placement of an adapter required for supporting a drum liner. 
     The bottom surface  32  of the drum allows for the relatively easy installation of a larger adapter  26  and a liner  22  with a larger opening, as opposed to a conventional installation. Another advantage related to the installation of the drum liner system in the bottom surface  32  of a metal drum is that the large opening through the adapter  26  is usable for washing, sand blasting and painting the interior of the drum while using the bung hole  36  and vent plug  38  as drain openings to assist in doing this work. 
     The modification of a metal drum  30  is effected by cutting an opening in the bottom  32  of the drum with a chisel, shears, nibbling machine or otherwise and by rivetting the adapter  26  to the opening. Rolled and sealed rivets  40  are preferred for retaining the flange of the adapter  26  to the bottom surface  32 , but other fasteners can also be used. 
     It is believed that the useful life of a steel drum for example is about 7-8 years. It is further believed that the installation of a drum liner system therein can extend the life cycle of the drum by another 10 to 12 years. Common steel drums are generally easily available at low cost. Therefore, the modification of a steel drum and the installation therein of a drum liner system according to the preferred embodiment represents substantial savings to a producer as compared to the purchase of new drums, plastic barrels or stainless steel containers. 
     Referring now to FIGS. 4 and 5, the cover  28  of the liner support system according to the preferred embodiment has a cylindrical configuration which is closed at one end and has an internal thread  50  on the inside surface thereof. The cover  28  also has a bung hole  52  at the center of the closed surface  54 . A pair of smaller openings  56 ,  58  are also provided in the closed surface  54  for the convenience of the user. These smaller openings  56 ,  58  can be used for examples as vent holes, as sampling holes or to install pressure relief devices (not shown). 
     A pair of parallel ribs  60  extends across the closed surface  54  on each side of the bung hole  52  and are raised above the closed surface  54 . These ribs are advantageous for turning the cover  28  and for engaging the internal thread  50  over the adapter  26  during the assembly of the liner support system  20 , as will be explained further hereinafter. 
     The adapter  26 , as it can be seen in FIGS. 6,  7  and  8 , has an annular flange  70  with a plurality of holes  72  therein for bolting or rivetting the flange to the surface of a drum. Bordering the inside edge of the flange  70 , there is provided a circular channel  74  connected to the flange  70 . The channel  74  has an outside circular wall  76  the section of which makes a right angle with a plane define by the flange  70 , and an inside circular wall  78  parallel to and at a distance from the outside circular wall  76 . The outside surface of the inside circular wall  78  relative to the central region of the adapter  26  has a first external thread  80  which corresponds in dimensions and pitch to the internal thread  50  in the cover  28 . The internal thread  50  is mountable over the first external thread  80  for securing the cover  28  to the adapter  26 . 
     The inside surface of the inside wall  78  relative to the central region of the adapter  26  has a series of equally spaced internal notches  82  formed therein. The function of these notches  82  will be explained later when describing the assembly of the liner collar  24  in to the adapter  26 . 
     Referring now to FIGS. 9-12, the liner collar  24  will be described in details. The liner collar  24  has a sleeve-like portion  90  with a lower circular lip  92  and an upper annular shoulder  94 . In use, the annular lip  92  is bonded to the opening of the plastic liner  22  for supporting the liner  22  thereto. 
     The outside surface of the annular shoulder  94  is shaped to form a second external thread  96 . This second external thread  96  has dimensions and a pitch similar to the first external thread  80 . The second external thread  96  is continuous with the first external thread  80  when the liner collar  24  is mounted over the adapter  26 . The internal thread  50  in the cover has more turns than the external threads on either the adapter or the liner collar. Therefore, the internal thread  50  of the cover  28  is simultaneously mountable over the first and second external threads  96 ,  80 . 
     The liner collar  24  also has two series of external notches thereon  98  and  100  which are diametrically opposite from each other on the sleeve portion  90 . The external notches  98  and  100  are engagedly mountable into the internal notches  82  when the liner collar  24  is installed in the adapter  26 . The internal notches  82  in the adapter  26  are tapering in a counterclockwise direction when looking at the adapter  26  from the top. The external notches  98  and  100  are tapering in a clockwise direction. The respective diametrical spacings of the notches  82  and  100 , 98  are selected to provide an interference therebetween, when the liner collar  24  is mounted in the adapter  26 . 
     Because of the tapering arrangement of the notches  82  and  98 ,  100 , the interlocking engagement is obtained only when the liner collar  24  is urged in a counterclockwise direction relative to the adapter  26 . In other words, the interlocking engagement is obtained when the cover  28  is being removed from the liner collar and the adapter assembly  24 , 26 . 
     The preferred liner collar  24  is made of resilient plastic material and the interference mentioned above is smaller than an allowable deformation thereof. Therefore, when the liner collar  24  is rotated in a clockwise direction relative to the adapter  26 , the external notches  98 ,  100  are allowed to slip over the internal notches  82 . This feature is particularly advantageous for firstly installing a liner collar  24  inside a cover  28 , and then for mounting the liner collar and cover assembly  24 , 28  to the adapter  26 . 
     The liner collar  24  has two series of notches  98 ,  100  as opposed to a continuous series of notches. The reason for this being for reducing a friction generated between the notches and a corresponding effort required to install the liner collar and cover assembly  24 , 28  to the adapter  26 . The plain segments  102  between the series of notches  98 ,  100  can be longer or shorter than the illustrated embodiment, depending upon the dimensions and the resilience of the material used in the manufacturing of the liner collar  24 . 
     The overall diameter ‘A’ of the lip  92  in the liner collar  24  is an interference fit inside the diameter ‘B’ of the adapter  26 , such that the installation of the liner collar  24  in the adapter  26  requires a slight effort by the user, and such that its proper placement in the adapter  26  is confirmable by a sudden reduction of this effort. For this purpose also, the height ‘C’ of the sleeve portion  90  on the liner collar  24  is greater than the height ‘D’ of the inner wall  78  of the adapter  26 . 
     The interference fit mentioned above between the lip  92  and the inside diameter ‘B’ of the adapter  26 , is also advantageous for retaining a liner  22  to a drum when the liner  22  is pulled inside-out for example as illustrated in FIG. 13, and as will be explained hereinbelow. 
     The liner collar  24  also has a series of indentations  104  on the underside of the shoulder  94 . These indentations  104  which are partly seen in FIG. 11, are useful for receiving a pair of pins on a manual tool (not shown) for installing the liner collar  24  in to the cover  28 , when such tool is used. 
     The liner collar  24  also has several vent slots  106  for allowing air to escape from outside a liner  22  being deployed in a drum. When the liner collar  24  is installed in the cover  28 , these vent slots  106  communicate through the thread  50  of the cover with one or more vent holes  108  through the cylindrical wall  110  of the cover  28 , as may be understood by looking at the illustrations in FIGS. 3,  10 ,  11 ,  14  and  15 . 
     Referring now particularly to FIGS. 12 and 13, an important dimension of the liner collar  24  is a relatively large inside diameter ‘D’. In the preferred embodiment, the inside diameter ‘D’ is at least about six to seven inches, but preferably about seven inches or more. This range of dimensions has been found to be appropriate for affording a relatively easy manipulation of the liner  22  during installation thereof in a drum, and for pulling this liner  22  inside-out of the liner collar  24  as illustrated in FIG.  13 . The liner  22  and liner collar  24  can then be taken out of the drum and rinsed with hot water for example, for recovering maple syrup which had adhered to the inside surface thereof for example. 
     The large inside diameter ‘D’ also has the advantage of requiring an equally large inside diameter ‘B’ for the adapter  26 . In the preferred embodiment, the diameter ‘B’ is at least about eight to nine inches or more, whereby a metal drum having the adapter  26  installed thereon is easily washed, sand-blasted and painted through the opening defined by the adapter  26 . For example, a  32  imperial gallon drum can accommodate an adapter  26  having an inside diameter ‘B’ of up to about 13 inches or slightly more. 
     Referring now to FIGS. 14 and 15, the thread engagement of the drum liner support system according to the preferred embodiment and the corresponding advantages will be explained. As it was mentioned before, the first external thread  80  on the adapter  26 , and the second external thread  96  on the liner collar  24  have a same shape and pitch. Therefore, when the liner collar  24  is mounted inside the adapter  26 , the cover  28  may be continuously threaded over both external threads  96  and  80 . 
     During the installation of the cover  28  over the adapter  26  and the liner collar  24 , the collar  24  is able to slip over the adapter  26 , because of the notches  82 ,  98  and  100 , until the internal thread  50  in the cover  28  finds the start of the first external thread  80  in the adapter  26  and engages with this thread  80 . 
     When the cover  28  is being installed over the adapter  26  and liner collar  24  assembly, and the second external thread  96  reaches the top  120  of the internal thread  50 , a friction between the cover  28  and the liner collar  24  causes the liner collar  24  to move with the cover  28  to create a locknut effect. As can be understood, a slipping of the liner collar  24  in the clockwise direction as represented by arrow  122  in FIG. 14, causes the first and second threads  80 ,  96  to move away from each other vertically. This spreading of the threads  80  and  96  causes a pressure to occur at surfaces  120  and  124  on the internal thread  50  of the cover  28 , and at the common bearing surface  126  between the liner collar  24  and the adapter  26 . 
     This slight misalignment of the first and second external threads  96  and  80  causes the liner collar  24  to act as a locknut over the adapter  26  to prevent the cover  28  from loosening during transport and handling of a drum on which the liner system  20  is installed. 
     When the cover  28  is being rotated in the counterclockwise direction, the engagement of the notches  82 , 98 , and  100  prevents the liner collar  24  from turning relative to the adapter  26 , thereby allowing the removal of the cover  28 . This feature is also appreciable for preventing the rotation and mangling of a deployed liner  22  when the cover  28  is being removed from the liner collar and adapter. 
     In regard to other features of the cover  28 , an O-ring  128  is preferably provided therein for sealing the cover  28  over the liner collar  24 . A circular lip  130  is also provided on the circumference of the cover  28  to engage over a circular shoulder  132  on the adapter  26 . The overlapping of the lip  130  over the shoulder  132  prevents dust and other particles from entering the annular channel  74  of the adapter  26 . 
     In FIG. 16, there is illustrated a preferred package for shipping a clean liner  22  and liner collar  24  to a user. Because the inside diameter ‘D’ and the depth ‘E’ of a liner collar  24  are relatively large, the liner  22  is foldable inside the liner collar  24 . For this purpose and other objectives mentioned herein before, the depth ‘E’ of the liner collar  24  is preferably about 2 inches. 
     A liner collar  24  and a liner  22  are preferably manufactured and sterilized under controlled conditions at the manufacturing plant, and shipped to a user in a wrapped and sealed condition in a plastic wrapper  134  for example. When the liner  22  is reused several times, it is preferably washed and sterilized under controlled conditions and similarly wrapped and sealed before shipment. 
     For those applications where extreme cleanliness is required, such as in the food industry for example, it is preferable to install a sterilized liner  22  and liner collar  24  inside a sterilized cover  28  having the O-ring  128 , for sealing the liner collar  24  to the cover  28 , before wrapping and sealing this assembly. A storing, delivery and installation of the liner  22  can thereby be effected without ever exposing the interior of the liner  22  to ambient air. In these applications, it will be appreciated that one of the openings  56 , 58  in the cover  28  may be used for applying a vacuum to this assembly during packaging. 
     An alternate use of the adapter  26  and cover  28  is illustrated in FIGS. 17 and 18. In this particular application, a ring  136  which has substantially a similar outside diameter as the inside wall  78  of the adapter  26 , is placed inside a collar-less liner  138  and over the inside wall  78  of the adapter  26 . Upon filling, the collar-less liner  138  is allowed to slip between the ring  136  and the inside wall  78  and to expand inside a drum. This application is particularly appreciable for allowing a liner  138  to expand against all inside surfaces of a drum during filling, to avoid the creation of air pocket between the drum and the liner  138 . 
     When the drum is full, the neck of the liner  138  is folded inside the ring  136  and the cover  28  is installed over the adapter  26  to cover the ring  136  and the liner  138 . The ring has a thickness ‘F’ which is substantially the same as the thickness of the upper annular shoulder  94  on the liner collar  24 , such that the cover  28  is still mountable over the adapter  26 . In this installation, however, an additional O-ring  140  is preferably installed inside a groove  142  defined by the lip  130  and the cylindrical wall  110  of the cover  28 , between the cover  28  and the circular shoulder  132  of the adapter  26 , to prevent contaminant from entering the circular channel  74  of the adapter  26  and for preventing contaminant from entering the liner  138 . It will also be appreciated that this double O-ring arrangement  128 ,  140 , can also be used with the liner collar  24 , as explained hereinbefore. 
     As to additional details related to the manufacturing, installation and use of the drum liner system  20  of the present invention, the same should be apparent from the above description, and accordingly further discussion relative to the manner of making and using this system would be considered redundant and is not provided. 
     While one embodiment of the present invention has been described herein above, it will be appreciated by those skilled in the art that various modifications, alternate structures, alternate mounting arrangements and equivalents may be employed without departing from the true spirit and scope of this invention. Although the advantages of the drum liner system of the present invention has been described for use in storing and transporting maple syrup, it will be appreciated by those skilled in the art that similar advantages are obtained in the production and commerce of molasses, jams, sauces, beverage concentrates, water and even in the transport of granular fertilizer products for examples. Therefore, the above description and illustrations should not be construed as limiting the scope of the invention which is defined by the appended claims.