Patent Publication Number: US-2013248407-A1

Title: Lightweight disposable drum

Description:
BACKGROUND 
     1. Field of the Invention 
     This application relates generally to drums and methods of forming drums. More specifically, this application relates to disposable and lightweight drums and methods of forming such drums. 
     2. Background of the Invention and Related Art 
     Some waste materials are commonly incinerated in waste treatment plants. Incinerators burn waste using temperatures up to and over one thousand degrees Fahrenheit. Incineration facilities typically receive and incinerate hazardous and non-hazardous waste in liquid, solid, semi-solid, sludge and gas forms. Examples of incinerated waste includes industrial, medical, and municipal waste such as inorganic cleaning solutions, oil, spent flammable solvents, laboratory chemicals, paint residues, toxic or reactive chemicals, infections and medical waste, household hazardous materials, and other such materials. Incineration is particularly effective in treating hazardous waste where pathogens and toxins can be destroyed by the high temperatures. When incinerated, these materials are converted into ash, flue gas, and heat. The remaining solid mass is a mere fraction of the volume of the original waste, such as less than ten percent the initial volume. 
     In some incineration process, waste materials are placed in containers, such as 55-gallon drums, or cylindrical containers, as they are transported to the incinerator. The drums assist to contain the waste materials and prevent spills or accidents. The drums are particularly useful when incinerating liquids, which must be contained until the liquids arrive at the incinerator. Some processes incinerate the drum along with the waste materials; these processes are drum-dependent and need a constant supply of disposable drums in order to maintain constant operation of the incineration facility. 
     The need for a constant supply of low-cost, disposable drums has been long-felt and onerous. Drums are commonly made in 30 gallon and 55-gallon sizes and are used to ship various products from oil to food products. Plastic drums are available. However, because existing 55-gallon plastic drums are made of approximately twenty two pounds of plastic, it has not been economically feasible to manufacture or purchase new plastic drums for the incineration process because the cost of that much plastic, metal, or composite material is relatively high. Instead, incineration facilities have historically purchased used drums that are not otherwise reusable. An example of a used drum is a plastic, steel, or composite 30-gallon or 55-gallon drum that was previously used to ship food products, liquids, or oils. These drums have historically been acquired from industrial and manufacturing plants known to have used drums. 
     Because incinerating factories can be dependent on third parties for a supply of used incinerators can face difficulties when known suppliers do not have a ready supply of used drums. As a result, some incinerating facilities utilize large amounts of employee time in locating, acquiring, processing and transporting used drums. When drums are not available locally, incinerating facilities are forces to ship drums from long distance. Some incinerating facilities have been known to ship used drums over thousands of miles, which can dramatically increase the cost of acquiring drums. Other incinerating facilities have paid up to two or three times the average drum cost for used drums when drum supplies are low. 
     Shipping used drums involves various disadvantages. For example, because drums are initially sealed over when initially used, used drums frequently still have a sealed lid or top. As such, used drums can take up a lot of space in shipping because they must be stacked on top of each other. Thus, when shipped in a standard shipping container, used drums are typically stacked only three high, which provides room for only about 340 to 360 used drums in a standard semi-trailer. Moreover, these drums must usually be loaded and unloaded by hand, which increases the overall cost and labor involved. As such, the cost of shipping used drums can be very expensive and labor intensive. The use of used drums can thus present a large number of challenges to incinerating facilities. 
     Accordingly, it would be advantageous to overcome the challenges presented with the current use of known plastic drums or other used drums in incinerating facilities. 
     SUMMARY AND OBJECTS OF THE INVENTION 
     The present invention has been developed in response to limitations in previous disposable drum solutions and needs in the art that have not yet been fully resolved by currently available plastic or used drums. Thus, the present invention is directed to a disposable drum that has a net weight of less than or equal to about nine pounds of plastic and an internal volume of at least about 35 or 40 gallons. The drum body also has a generally tapered shape that enables another disposable drum to be substantially inserted into the cavity of the drum body. Despite its lightweight properties, embodiments of the drum body can be configured to support a vertical load up to, for example, about 600 to about 800 pounds. Thus, the present drum can be made of a small enough amount of material to provide an economically feasible option for incinerating processes. Furthermore, given its potential strength capabilities and adequate internal volume, the present drum can effectively replace the need for used drums. Some embodiments of the drum can also be stackable, permitting compact shipment and thus lower shipping costs. 
     These and other features and advantages of the present invention may be incorporated into certain embodiments of the invention and will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter. The present invention does not require that all the advantageous features and all the advantages described herein be incorporated into every embodiment of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order that the manner in which the above recited and other features and advantages of the present invention are obtained, a more particular description of the invention will be rendered by reference to specific embodiments thereof, which are illustrated in the appended drawings. Understanding that the drawings depict only typical embodiments of the present invention and are not, therefore, to be considered as limiting the scope of the invention, the present invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: 
         FIG. 1  illustrates a perspective view of one embodiment of a representative drum. 
         FIG. 2  illustrates a close-up view of a top exterior detail portion of one embodiment of a representative drum. 
         FIG. 3  illustrates a side, perspective view of a stack of representative drums. 
         FIG. 4  illustrates a partial cross section view of a top portion of one embodiment of a representative drum and a representative lid. 
         FIG. 5  illustrates a partial cross section view of a top portion of another embodiment of representative drum and another representative lid. 
         FIG. 6  illustrates a cross section view of a bottom portion of one embodiment of a representative drum and a representative spacer. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     It will be readily understood that the components of the present invention, as generally described and illustrated in the figures herein, could be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of the embodiments of the system and method of the present invention is not intended to limit the scope of the invention, as claimed, but is merely representative of the presently preferred embodiments of the invention. 
     A description of embodiments of the present invention will now be given with reference to the Figures. It is expected that the present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope. 
     The following disclosure of the present invention may be grouped into subheadings. The utilization of the subheadings is for convenience of the reader only and is not to be construed as limiting in any sense. 
     For the purposes of the present invention, the phrase “A/B” means A or B. For the purposes of the present invention, the phrase “A and/or B” means “(A), (B), or (A and B).” For the purposes of the present invention, the phrase “at least one of A, B, and C” means “(A), (B), or (C), (A and B), (A and C), (B and C), or (A, B and C).” 
     Various operations may be described as multiple discrete operations in turn, in a manner that may be helpful in understanding embodiments of the present invention; however, the order of description should not be construed to imply that these operations are order dependent. 
     The description may use the phrases “in an embodiment,” or “in various embodiments,” which may each refer to one or more of the same or different embodiments. Furthermore, the terms “comprising,” “including,” “having,” and the like, as used with respect to embodiments of the present invention, are synonymous with the definition afforded the term “comprising.” 
     The terms “coupled” and “connected,” along with their derivatives, may be used. It should be understood that these terms are not intended as synonyms for each other. Rather, in particular embodiments, “connected” may be used to indicate that two or more elements are in direct physical contact with each other. “Coupled” may mean that two or more elements are in direct physical or electrical contact. However, “coupled” may also mean that two or more elements are not in direct contact with each other, but yet still cooperate or interact with each other. 
     The description may use perspective-based descriptions such as up/down and top/bottom. These descriptions refer to the orientations and parts of a drum during normal use, with the opening in the drum being at the top or top portion. Similarly, the terms inside/outside and in/out are used in their common meaning, referring to the inside parts of a drum within its hollow interior or cavity and the outside parts referring to outer surfaces. 
     This application relates generally to drum devices and methods of forming container devices. More specifically, this application relates to disposable and/or lightweight drums and methods of forming such drums. 
     The drums of the present invention have been developed in response to limitations in previous disposable drum solutions and needs in the art that have not yet been fully resolved by currently available drums. Thus, the present invention is a disposable drum having a net weight of less than or equal to about nine pounds of plastic of polymeric material and an internal volume of at least about 35 or 40 gallons. The drum body also has a generally tapered shape that enables another disposable drum to be substantially inserted into a cavity of the drum body. Despite its lightweight properties, embodiments of the drum body can be configured to support a vertical load up to, for example, about 600 to about 800 pounds. Thus, the present drum can made of a small enough amount of material to provide an economically feasible option for incinerating processes. Furthermore, given its potential strength capabilities and adequate internal volume, the present drum can effectively replace to the currently available drums. Some embodiments of the drum can also be stackable, permitting compact shipment and thus lower shipping costs. 
     Representative Drums 
     Reference will first be made to  FIG. 1 , which illustrates a perspective view of a drum  10  that can be used to carry materials in incinerating processes. Generally, the drum  10  includes a drum body  12  having a top end  14  and a bottom end  16 . The drum body  12  can generally include a sidewall  18  and a bottom wall  20 . The sidewall  18  can form a generally tapered cylindrical shape about an inner cavity  24  that opens through an opening  22  in the top end  14  of the drum body  12 . For convenience, before turning to a discussion of these individual components and features, common characteristics and features shared by some embodiments of the drum  10  will be discussed for convenience. 
     In some embodiments, the drum  10 , including all of its component parts, is made from any desirable material with suitable properties and/or characteristics. By way of non-limiting example, in some embodiments, the drum  10  is made of one or more of the following materials or combinations thereof: polymer materials, composite materials, synthetic materials, wood or fibrous materials, or resins. For example, the drum  10  can comprise or consist essentially of a polymer material such as polypropylene or a recycled plastic. The use of recycled plastic may reduce manufacturing costs. Examples of recycled plastic materials include recycled plastic and a resin. Some recycled plastic materials or other polymer materials can include calcium, which can strengthen the material. When used, plastic drums  10  made of another such polymer material can reduce the fuel required in incineration processes because these materials can act as a fuel source themselves. Further, in some embodiments, the desirable or selected material is homogenous or uniform throughout while in other embodiments the selected material includes voids or encapsulates non-homogenous materials. 
     In addition, in some embodiments, the drum  10 , including its component features, can be manufactured together as a single piece structure by any suitable method. By way of non-limiting example, in some embodiments, some or all of the component parts of the drum  10  is/are manufactured by one or more of the following methods: injection molding, rotational molding, blow molding, casting and/or other molding processes, machining, cutting, carving, routing, punching, milling and/or other suitable forming or manufacturing processes. For example, in some embodiments, the drum  10  is manufactured using a blow molding process. Two potential benefits involved in blow molding are the ability to control the thickness of portions of the sidewall  18  and bottom wall  20  and the ability to rapidly manufacture a drum  10 . For instance, a blow molding process can have a cycle time of approximately one to two minutes or less. 
     Because the drum  10  may eventually be consumed in an incinerating process, it is desirable to manufacture the drum  10  efficiently and economically. Accordingly, the drum  10  can be manufactured out of a relatively low amount of material, which can reduce manufacturing costs. By reducing the economic cost of the drum  10 , the drum  10  can be disposable in the incinerating processes. Accordingly, non-limiting examples of the drum can have a net weight of between about 5 and about 15 pounds depending upon the strength needed. Specifically, in various embodiments, the drum  10  can have a net weight of less than about 5 pound, less than about 6 pound, less than about 7 pound, less than about 8 pound, less than about 9 pound, less than about 10 pound, less than about 11 pound, less than about 12 pound, less than about 13 pound, less than about 14 pound, and less than about 15 pound. In other embodiments, the drum  10  can have a net weight of greater than 15 pounds. Furthermore, drums  10  of these net weights can have an inner cavity  24  with an internal volume of between about 30 to about 60 gallons, including about 30 to about 35 gallons, about 35 to about 40 gallons, about 40 to about 45 gallons, about 45 to about 50 gallons, about 50 to about 55 gallons, and about 55 to about 60 gallons. 
     For example, a representative drum  10  can have a net weight of approximately 7 to 8 pounds and have an inner cavity  24  with an internal volume of about 40 to 50 gallons. Another representative drum  10  can have a net weight of approximately 8 to 10 pounds and have an inner cavity  24  with an internal volume of about 40 to 50 gallons. Yet another representative drum  10  can have a net weight of approximately 10 to 12 pounds and have an inner cavity  24  with an internal volume of about 40 to 50 gallons. Still another representative drum  10  can have a net weight of approximately 12 to 15 pounds and have an inner cavity  24  with an internal volume of about 40 to 50 gallons. Such drums  10  can be substantially lighter and thus less expensive than available prior art drums, such as the 22 pound plastic 55-gallon drum previously mentioned. 
     Referring still to  FIG. 1 , reference will now be made to the specific shapes, component, and characteristics of the drum body  12  of the drum  10 . As shown, the drum body  12  can include a generally tapered shape, tapering from a larger diameter at top  14  to a smaller diameter at bottom  16 . For example, in some instances, the top diameter of the top end  14  can be between about 21 inches and about 25 inches, and the bottom diameter of the bottom end  16  can be about 17 inches and about 21 inches. In other instances, the top diameter of the top end  14  can be between about 18 inches and about 28 inches and the bottom diameter of the bottom end  16  can be about 16 and about 26 inches. In a specific embodiment, the top diameter is about 23 to 23.5 inches and the bottom diameter is about 19 to 20 inches. Because the bottom diameter can be smaller than the top diameter, a second similar drum  10  can be received into the inner cavity of the drum  10 . This ability can allow multiple drums to be stacked in a manner that occupies a reduced amount of space than occupied by former used drums having enclosed tops or otherwise substantially parallel sidewalls. A stack of representative drums  10  is illustrated in  FIG. 3 , which is described below. 
     As shown, for convenience, the drum body  12  can be described generally as having a upper portion  50 , a lower portion  52 , and a bottom portion  54 . Reference will first be made to the upper portion  50 , a close-up view of which is depicted, according to some embodiments, in  FIG. 2 . As shown in  FIG. 2 , the upper portion  50  can include a flanged rim  26 , a neck  28 , a first upper bevel  30 , an annular ring  32 , a lip  34 , and a second lower bevel  36 . The flanged rim  26  can form at least a portion of the top  14  drum  10 . The flanged rim  26  can have a vertical and/or horizontal thickness to provide strength and volume to the upper portion  50  of drum  10 . The flanged rim  26  can be configured, shaped, and sized to be gripped by or receive a parrot clamp or other device for handling on an underside of flange  26 . Once gripped, the entire drum  10  including the drum&#39;s internal contents can be carried by the parrot clamp. As further shown, beneath the flanged rim  26  is a neck  28  that forms an inward oriented surface that can facilitate gripping of the flanged rim  26  as well as accommodate a lid or lid securing component, as described below and shown in  FIGS. 4 through 5 . 
     Below the neck  28 , the drum  10  can have a first or upper beveled surface, or bevel,  30  that extends radially outwardly as is extends downward. In some embodiments, the bevel  30  extends downward between about 1 inch to about 10 inches, about 2 inches to about 7 inches, or about 4 inches to about 6 inches. In some embodiments, the drum body  12  does not include this bevel  30 . The bevel  30  can terminate at its lower end at or near the peak of the annular ring  32 . The annular ring  32  can function as a strength or stiffening ring, to fortify the upper portion  50  of the drum body  12 , which can provide increase the drum&#39;s load bearing abilities. Additionally, the annular ring  32  can provide the annular width needed for a lower ledge or lip  34 . In some configurations, the drum body  12  does not include an annular ring  32 . 
     The lip  34  can provide a flat or substantially flat undersurface of drum body  12  that is conveniently disposed along upper portion  50 . The undersurface of the lip  34  can be used to raise, grip and/or carry the drum  10  using a barrel clamp, fork lift, or other such device. The undersurface of the lip  34  also provides a resting surface that limits the downward travel of the drum  10  when it is inserted into another drum  10  during storage and transport. By limiting the downward travel, the lip  34  can avoid the problem of adjacent drums  10  getting stuck together. The lip  34  can also provide a convenient surface that can be grabbed with the hand when manually lifting the drum  10 . As shown, in some embodiments, the lip  34  can be rounded. In other embodiments, the lip  34  is square, angular or otherwise formed. In some embodiments, the lip  34  and its undersurface can extend radially outward between about 0.5 inches to about 4 inches, about 0.75 inches to about 2 inches, or about 1 inch to about 1.5 inches. In some instance, no lip  34  is formed under the annular ring  32 . 
     Beneath the lip  34  or annular ring  32 , the drum  10  can have another beveled surface, or bevel,  36  that tapers radially inwardly as it extends downward. In drum embodiments incorporating the first or upper bevel  36 , this bevel  36  can be a second or lower bevel  30 . In some embodiments, the lower bevel  36  is present, but not the upper bevel  30 . Bevel  36  can provide a gradual transition from lower portions of the drum  10  to the lip  34 . Accordingly, the bevel  36  can tapering inward with a steeper incline than the general taper of the middle portion  52  and bottom portion  54  of the drum body  12 . 
     Bevel  36  can also functions to permit the flow of air in adjacent drums  10  when stacked, to at least partially avoid the problem of adjacent drums  10  getting stuck together. In some embodiments, bevel  36  extends downward between about 1 inch to about 8 inches, about 2 inches to about 6 inches, or about 4 inches to about 5 inches. In other embodiments, the drum body  12  does not include a lower bevel  36 , but the lip  34  or other upper structure connects directly to middle portion  52  of the drum body  12 . 
     Reference will again be made to  FIG. 1  and specifically to the middle portion  52  and the lower portion  54  of the drum body  12 . In generally, the middle portion  52  and lower portion  54  can include a gradual radially inward taper as sidewall extends downward. In some embodiments, the middle portion  52  and the lower portion  54  are graduated or stepped, with the step occurring at a transition  40  or an inwardly directed annular ring (not shown), outwardly directed annular ring(not shown), or other suitable feature. These features can also strengthen or stiffen the drum body  12  and increase its load-bearing abilities. In these embodiments, the middle portion  52  can have approximately the same length as the lower portion  54 . Alternatively, the middle portion  52  can be between about 5% to about 100% longer than the bottom portion, including between about 5% to about 25%, about 25% to about 50%, about 50% to about 75%, about 75% to about 100%. In other embodiments, two or more such transitions  40 , rings, or other strengthening features are formed at one or more locations along the middle portion  52  or lower portion  54 . For example, the middle portion  52  and the lower portion  54  can include two, three, four, five, six, or more than six transitions  40 , rings, or other strengthening features. Such embodiments can include transitions  40  or rings formed equidistantly apart or otherwise strategically or occasionally placed. As further shown, the bottom portion  54  can include a rounded edge  44  that strengthens the bottom end  16  of the drum body  12 . 
     As mentioned, in various embodiments, the drum  10  can have a net weight of construction material between about 5 pounds and about 15 pounds. To provide such a lightweight drum body  12 , the thicknesses of the sidewall  18  and bottom wall  20  can be controlled and limited. For instance, in some embodiments, the maximum thickness of the sidewall  18  and bottom wall  20  can be about 0.15 inches with an average thickness of between about 0.1 inches and about 0.135 inches. Specifically, the flanged rim  26  can have an average thickness between about 0.075 inches and about 0.125 inches or between about 0.09 inches and about 0.11 inches. The first bevel  30 , the annular ring  32 , and/or the lip  34  can have an average thickness between about 0.08 inches and about 0.145 inches or between about 0.1 inches and about 0.13 inches. The second bevel  36  can have an average thickness between about 0.08 inches and about 0.15 inches or between about 0.1 inches and about 0.14 inches. The middle portion  52  of the drum body  12  and the bottom portion  54  of the drum body  12  can have an average thickness between about 0.08 inches and about 0.135 inches or between about 0.1 inches and about 0.13 inches. The bottom rounded edge  44  can have an average thickness between about 0.05 inches and about 0.135 inches or between about 0.65 inches and about 0.13 inches. Additionally, in embodiments using blow molding manufacturing, the thickness of a joints formed in the drum body  12  can be reinforced with an increased thickness of an additional 5% to 100% thickness, including about 5% to about 25%, about 25% to about 50%, about 50% to about 75%, about 75% to about 100% to that of the thickness of an adjacent wall of the same portion of the drum body  12 . 
     The combination of wall thicknesses and features of the drum body  12  can combine to provide a drum  10  that is shaped and structured to support the load of multiple filled drums  10 . This can allow filled drums to be stacked, as is customary in some incinerating processes. For instance, in some incinerating processes, multiple filled drums  10  can be placed on a pallet or other object and/or stacked upwards, including up to four levels high with a pallet or other relatively flat object between each level. A drum  10 , such as a 40 to 50 gallon drum may be customarily filled with contents weighing up to 175 pounds to 250 pounds or more. Accordingly, a drum  10  may be subject to a vertical load of up to 500 or even 800 pounds. In some instances, the vertical load may be up to or above 1,000 pounds. Accordingly, in some embodiments, the drum  10  that is shaped and structured to support the load of up to about 600 pounds, up to about 800 pounds, or up to about 1,000 pounds resting a top portion of the drum body  12 . 
     Reference will now be made to  FIG. 3 , which illustrates a stack of empty drums  10 . As shown, during transportation, storage, or when otherwise not being used, a set of drums  10  can be stacked vertically, with each upper drum  10  being inserted into the cavity  24  (shown in  FIG. 1 ) of another lower drum  10 . This is at least partially facilitated by the generally tapered shape of the drum body  12 . As shown, the stack of drums  10  includes five drums  10 . However, in transit, it has been found that between about ten and about twenty drums  10  can be stacked vertically within a standard shipping container. In some specific instances about four stacks of about fifteen drums  10  can be placed on a pallet within a standard shipping container. In these instances, about 1660 drums can be shipped in a standard shipping container, which is a dramatic increase over the prior 300 to 350 used drums that fit into a standard shipping container, as mentioned above. This increase in volume can reduce the overall cost of shipping drums  10 . 
     As shown, each drum  10  can be inserted into a lower drum  10  up to the annular ring  32  of the top drum. Because in some embodiments the annular ring  32  extends outwardly farther than the opening  22  of the lower drum  10 , this annular ring  32  can limit the depth to which the drum  10  can be inserted into the lower drum  10 . As further shown, the portion  60  of the drum  10  which extends out of the lower drum  10  can be the portion of the drum  10  that is above the annular ring  32 . This portion  60  can have a length of between about 1 inch and about 12 inches, including between about 2 inch and about 10 inches, and between about 3 inch and about 8 inches. 
     Reference will now be made to  FIGS. 4 and 5 , which illustrate embodiments of a lid  70 ,  80  that can be included with the drum  10 . Reference will first be made to  FIG. 4 , which illustrates a cross-section view of a lid  70  and a clamp  72  on a drum body  12  (which is not shown in cross section). As show, a flat lid  70  can be placed on top of the drum body  12  and fastened thereon using one or more clamps  72 . The one or more clamps  72  can have a top portion  76  with a flange that presses downward on a top surface of the lid  70 . The one or more clamps  72  can also have a lower portion  74  with a flange that presses upwards on a bottom surface of the flanged rim  26  to secure the lid  70  to the flanged rim  26 . In some instances, the lid is secured by two or more clamps  72 , including up to four, six, ten, or more than ten clamps  72 . 
     Referring now to  FIG. 5 , in some embodiments, a lid  80  can be included with the drum  10  that locks around the flanged rim  26 .  FIG. 5  illustrates a partial cross-section view of a lid  80  and a drum body  12  (which is not shown in cross section). As shown, the lid  80  can include an overlapping portion  82  that has a flanged bottom portion  84  that latches under the flanged rim  26  to secure the lid  80  to the flanged rim  26 . This lid  80  can reduce the need for manual application of clamps  72 . 
     In some embodiments, as with other portions of the drum  10 , the lid  70 ,  80  can be made from any desirable material with suitable clamps, properties and/or characteristics known to those skilled in the art. By way of non-limiting example, in some embodiments, the lid  70 ,  80  is made of one or more of the following materials or combinations thereof: polymer materials, composite materials, synthetic materials, wood or fibrous materials, or resins. For example, the lid  70 ,  80  can be made of a polymer material such as polypropylene or a recycled plastic. The use of recycled plastic can reduce manufacturing costs. Examples of recycled plastic materials include recycled plastic and a resin. Some recycled plastic materials can further include calcium, which can strengthen the material without adding substantial weight. When used, plastic lids  70 ,  80  can reduce the fuel required in incineration processes since the plastic material can act as a combustion fuel source. Further, in some embodiments, the desirable or selected material is homogenous or uniform throughout while in other embodiments the selected material includes voids or encapsulates non-homogenous materials. 
     Reference will now be made to  FIG. 6 , which illustrates cross section view of a bottom portion  54  of a drum body  12 , with a sidewall  18  and an adjoining bottom wall  20 . As shown, a spacer  90  can be located at one or more locations along the bottom portion  54  interior of the drum  10 . The spacer  90  can extend between a sidewall  18  and an adjoining bottom wall  20 . In some configurations, the spacer  90  is a substantially vertically-oriented ridge. In other configurations, the spacer  90  can be a bulge, bump, protrusion, dent, detent, or other inwardly oriented feature. The spacer  90  can limit the downward travel of another drum  10  that is inserted into the drum  10  to reduce the risk of the drums  10  becoming stuck together. 
     EXAMPLE 
     Reference will now be made to a specific example of a drum  10  and test results of one or more tests conducted with an actual drum. Reference will again be made to  FIG. 1 , which substantially illustrates the drum  10  manufactured and tested. The general parts and features of the drum  10  are illustrated and described above and will not be repeated here. The drum  10  was manufactured using a blow molding process. About 7 to about 8 pounds of a plastic material was used in the blow molding process. No other materials were used, and thus, the drum  10  had a net weight of between about 7 to about 8 pounds. The plastic material included a composition of at least recycled plastic beads manufactured by Chevron Corporation, resin, and calcium. 
     The drum  10  was manufactured to have an internal volume of about 42 gallons, a height of about 29.3 inches, a bottom diameter of about 19.4 inches, and a top diameter of about 23.3 inches. The flanged rim  26  had a minimum average thickness of 0.1 inches and a minimum thickness of 0.1 inches. The first bevel  30  and annular ring  32  had a minimum average thickness of 0.125 inches and a minimum thickness of 0.1 inches. The second bevel  36  had a minimum average thickness of 0.135 inches and a minimum thickness of 0.1 inches. The middle portion  52  and lower portion  54  had a minimum average thickness of 0.125 inches and a minimum thickness of 0.1 inches. The rounded edge  44  had a minimum average thickness of 0.125 inches and a minimum thickness of 0.065 inches. Additionally, the thickness of transitions formed in the drum body  12  were reinforced with an increased thickness of an additional 5% to 100% thickness, including about 5% to about 25%, about 25% to about 50%, about 50% to about 75%, about 75% to about 100%. 
     In testing, a set of similarly manufactured drums  10  were filled with approximately 250 pounds of fluid. A piece of plywood or similar material was set over the drum&#39;s opening  22  and a second drum  10  equally filled was set on top of the first drum  10 . Similarly, a third and fourth drums  10  were placed on top of the first. Accordingly, the bottom drum  10  held a vertical weight of between 750 to 800 pounds, including the weight of the drums  10 , the fluid, and the plywood. Several similar stacks of drums  10  were duplicated. These drums  10  were left outdoors in the summer sun and heat for approximately 24 hours. During this time, no failure of the drums  10  was observed, including any collapsing, folding, or rupturing. Accordingly, the about 7 to about 8 pound drums  10  were observed to be capable of supporting a vertical load of about 750 to about 800 pounds. 
     The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims, rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.