U.S. patent number 3,921,850 [Application Number 05/473,720] was granted by the patent office on 1975-11-25 for drum closure.
This patent grant is currently assigned to Kaiser Steel Corporation. Invention is credited to Joseph E. Powers.
United States Patent |
3,921,850 |
Powers |
November 25, 1975 |
Drum closure
Abstract
A closure for an opening in a bulk food storage drum such as a
drum lined with interior coatings of plastic, film, tin, or the
like, which also is capable of aseptic packing. The drum has an
opening in one of the planar and panels thereof which opening is
formed with an upwardly and outwardly flared lip which defines an
acute angle with respect to the plane of the end wall. The lip is
formed with minimal bending to avoid adversely affecting the film
and the bond between the film and the material (e.g., steel) of
which the drum is fabricated. A closure member or plug is
fabricated of similar material having one side coated. The closure
member has a cylindric mid-wall, at one end of which is a circular,
fluid impervious disc and at the other end of which is an outwardly
extending flange. The closure member fits into the opening and
carries an O-ring type gasket which is distorted or caused to flow
in response to movement of the member into the opening, thus
forming a fluidtight closure. The surface portion of the drum wall
beneath and outside of the lip is accessible for cleaning and
painting, thereby avoiding accumulation of rust and/or material
spilled during the filling of the drum.
Inventors: |
Powers; Joseph E. (Napa,
CA) |
Assignee: |
Kaiser Steel Corporation
(Oakland, CA)
|
Family
ID: |
27025915 |
Appl.
No.: |
05/473,720 |
Filed: |
May 28, 1974 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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423228 |
Dec 10, 1973 |
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Current U.S.
Class: |
220/310.1 |
Current CPC
Class: |
B65D
39/04 (20130101); B65D 53/02 (20130101); B65D
7/42 (20130101) |
Current International
Class: |
B65D
39/00 (20060101); B65D 39/04 (20060101); B65D
53/02 (20060101); B65D 53/00 (20060101); B65D
039/00 () |
Field of
Search: |
;220/306,307,308,309,310,357 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1,144,472 |
|
1969 |
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UK |
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752,445 |
|
1933 |
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FR |
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Primary Examiner: Price; William I.
Assistant Examiner: Hart; Ro E.
Attorney, Agent or Firm: Naylor, Neal & Uilkema
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part of commonly assigned,
co-pending application for U.S. Pat. Ser. No. 423,228, filed Dec.
10, 1973.
Claims
What is claimed is:
1. A closure for a drum having at least one generally planar end
wall with an opening therein, said closure comprising: a portion of
said end wall bounding said opening and defining a lip integral
with said end wall, said lip extending axially and radially outward
around said opening, residing at an acute angle with respect to
said planar end wall, being of a single thickness and having all
surfaces exposed to the exterior of the end wall, a smooth conical
interior surface merging into said opening and an outwardly exposed
distal edge, said distal edge being concentric with said opening
and residing in a plane substantially parallel with said end wall;
a closure plug having a cylindric mid-wall and including an O-ring
gasket circumscribing said mid-wall, a circular wall integral with
and extending across one end of said mid-wall, and an annular
flange integral with and extending outward from said mid-wall at
the end of the mid-wall opposite said circular wall, said mid-wall
having a diameter sized to fit within said opening and an axial
extent such that said circular wall is interior of said drum end
wall when said flange is in contact with the distal edge of said
lip, said closure plug being deformable so that the portion of said
mid-wall adjacent said circular wall can be radially expanded to
retain said closure plug in said opening and distort said O-ring
gasket into engagement with the smooth conical interior surface of
the lip and the surfaces of the closure plug opposed thereto to
seal said closure, said plug, lip and O-ring being so proportioned
that distortion of the O-ring is within its elastic limit when the
flange of the plug is in contact with the distal edge of the
lip.
2. A closure, according to claim 1, wherein said annular flange is
substantially perpendicular to said cylindric mid-wall and wherein
said flange is joined to said mid-wall by an integral arcuate wall
portion extending therebetween, said O-ring gasket having a radius
of curvature corresponding to said arcuate wall portion and being
distorted into sealing condition in response to movement of said
flange into contact with the outer edge of said lip.
3. A closure, according to claim 2, wherein the surface of said lip
and the surfaces of said flange and said mid-wall that are in
contact with said O-ring gasket have thereon a layer of inert
material bonded thereto.
4. A closure, according to claim 1, wherein the acute angle between
said lip and said planar end wall is about 45.degree..
5. A closure for a drum having at least one generally planar
circular end wall with an opening therein, said closure comprising:
a portion of said end wall bounding said opening and defining a lip
integral with said end wall and extending axially and radially
outward around said opening, said lip residing at an acute angle
with respect to said planar end wall so as to define a
frusto-conical wall concentric with said opening, said lip being of
a single thickness and having all surfaces exposed to the exterior
of the end wall and an outwardly exposed distal edge; a closure
plug having a cylindric mid-wall, a circular wall integral with and
extending across one end of said mid-wall, and an annular flange
integral with and extending outward from said mid-wall at the end
of the mid-wall opposite said circular wall, said mid-wall having a
diameter sized to fit within said opening and an axial extent such
that said circular wall is interior of said drum end wall when said
flange is in a fixed spatial relation to said frusto-conical wall;
and an O-ring circumscribing said mid-wall adjacent said annular
flange, said closure plug mid-wall being deformable so that the
portion of said mid-wall adjacent said circular wall can be
radially expanded to retain said closure plug in said opening and
compressively distort said O-ring within a volume bounded by said
frusto-conical wall, said flange and said mid-wall; and means for
limiting inward movement of said closure plug to establish said
spatial relation and to establish said volume at a magnitude to
compress said O-ring within the elastic limit thereof.
6. A closure, according to claim 5, wherein said inward movement
limiting means comprises an outer edge on said lip concentric with
said opening and residing in a plane substantially parallel with
said end wall, said flange having a radial extent sufficient to
contact said edge thereby limiting inward movement of said closure
plug.
7. A closure, according to claim 5, wherein said inward movement
limiting means comprises a downward extending rib formed on said
flange and adapted to contact said frusto-conical wall thereby
limiting inward movement of said closure plug.
8. A closure, according to claim 5, wherein said inward movement
limiting means comprises a rib on said mid-wall, said rib extending
radially outward sufficient to contact said frusto-conical wall
thereby limiting inward movement of said closure plug, said O-ring
being disposed intermediate said rib and said flange.
9. A closure, according to claim 5, wherein said container end wall
is formed with an integral reinforcing ring circumscribing said
opening, said ring having at least one integral oblique wall
portion disposed obliquely of said end wall.
Description
FIELD OF THE INVENTION
This invention relates to closures for drums and the like and more
particularly to closures for drums that are lined and are used for
bulk storing and shipping material such as foodstuffs, including
aseptic packaging thereof.
In packing foodstuffs in large drums, one of the practices is to
employ an aseptic technique. Such technique is characterized in
that the foodstuff and the container are sterile and in a
relatively cool state before the former is introduced into the
latter. In employing the aseptic technique, it is important that
all surfaces which the foodstuff is likely to contact be in a
sterile condition. This is typically achieved by coating one
surface of the container material (e.g., steel sheet) with an
interior coating of plastic, film, tin, or the like and by forming
the container and filling opening in such a manner that only the
lined surface is exposed to the foodstuffs. Of particular
importance is that the margin surrounding the opening be configured
so that only the lined surface of the container material is exposed
to contact by the foodstuff.
DESCRIPTION OF THE PRIOR ART
Known prior art closures include a lip surrounding the opening
which is rolled on a relatively small or tight radius of curvature.
Forming the closure in this manner unduly stresses the lining
material with a serious risk of failure and possible harmful effect
on the contents. The rolled lip also forms a virtually inaccessible
concavity surrounding the opening from which it is difficult to
clean foodstuffs or the like that have entered the concavity during
filling of the drum. Such material may deteriorate with time and,
although it is not in communication with the contents of the drum,
create an unpleasant and unsanitary condition. Finally, the lip,
when rolled totally, conceals the edge of the sheet material
(typically, steel) of which the drum is made so that such edge
cannot be coated with protective paint. Consequently, rust is
likely to develop and, although not adversely affecting the
contents of the drum, create an unpleasant and unsanitary
condition.
With the prior art rolled configuration, sealing is achieved with a
gasket. Either the gasket is specially fabricated at great expense
or a gasket material is flowed into position on the lid and post
cured. Moreover, the gasket is sealed by simple compression so that
the quality of the seal is proportional to the care with which the
closure is placed in the opening.
SUMMARY OF THE INVENTION
The principal object of the present invention is to provide a drum
closure that eliminates the above enumerated disadvantages present
in known prior art structures. This object is achieved by the
present invention by providing a lip surrounding the opening and
integral with the panel in which the opening is formed, which lip
is straight rather than rolled, the sole distortion occurring at a
relatively large radius bend between the plane of the drum panel
and the lip. Thus, the interior coating on the drum material is not
adversely affected in forming a lip. Moreover, the lip is formed at
an acute angle with respect to the plane of the drum wall in which
the opening is formed so as to make the concavity beneath the lip
accessible to cleaning and painting.
Another object is to provide a closure that employs a conventional
O-ring for a sealing gasket and is arranged to optimally exploit
the characteristics of the O-ring. This object is achieved by
providing a closure member or plug having a cylindric wall and an
outwardly extending flange that is generally perpendicular thereto
and that is joined to the cylindric portion by an arcuate wall
portion. An O-ring having a radius of curvature corresponding to
the arcuate portion is employed and is contacted by the closure
member throughout about 90.degree. of the O-ring periphery. When
the closure member is forced into contact with the above mentioned
lip, the O-ring deforms or "flows" because the upwardly facing lip
surface against which the O-ring rests is angularly disposed with
respect to both the cylindric wall and the flange of the closure
member. The space between the closure member and the lip is thus
generally triangular shaped whereby the O-ring can distort and
effect a virtually perfect seal therebetween.
A further object is to provide a closure structure which affords
optimal compression of an elastic O-ring and is immune to
compressing the O-ring beyond its elastic limit.
Another object is to provide a temporary closure member or plug for
the opening which is used during manufacture and completion of the
drum and which closure member is left in place during shipment of
the empty drum and until the drum is filled. The temporary closure
member is made of resilient molded plastic material which can be
quickly snapped into place in the opening. The temporary closure
member is arranged to avoid obstructing the concavity between the
lip and the drum panel on which the lip is formed in order to
facilitate cleaning and painting of the surfaces within such
concavity.
The foregoing together with other objects, features and advantages
of the invention will be more apparent after referring to the
following specification and accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a perspective view of a drum with the portions of the
closure according to the present invention shown in exploded
form.
FIG. 2A is a fragmentary view of a prior art closure typical of
those used in drums lined with an interior coating.
FIG. 2B is a fragmentary view of a prior art closure typical of
those used for drums lined with tin.
FIG. 3 is a fragmentary view, at enlarged scale, of a drum closure
according to the present invention before full engagement of the
closure plug.
FIG. 4 is similar to FIG. 3 with the closure plug in the fully
closed or engaged position.
FIG. 5 is a fragmentary view of the upper extremity of the lip that
encircles the opening according to the present invention.
FIg. 6 is a view of the opening with a temporary molded plastic
closure member or plug in place.
FIG. 7 is an exploded perspective view of another embodiment of the
present invention.
FIG. 8 is a cross-sectional view at enlarged scale of a fragment of
FIG. 7 in the unsealed condition.
FIG. 9 shows the structure of FIG. 8 in a sealed condition.
FIG. 10 is a view similar to FIG. 8 of still another embodiment of
the invention.
FIG. 11 is a view of the embodiment of FIG. 10 in the sealed
condition.
DESCRIPTION OF THE ILLUSTRATED EMBODIMENT
Referring more particularly to the drawing, reference numeral 12
indicates a drum that has a cylindric wall portion 14 and planar
circular end walls, the upper one of which is indicated at 16.
Centrally of planar end wall 16 is an opening 18 through which the
container is filled. Circumscribing opening 18 and formed integral
with end wall 16 is a lip 20. An O-ring sealing gasket 22 is
compressed against the upper surface of lip 20 by a closure member
or plug 24, which plug is retained in place by deformation thereof
in a more or less conventional way and is described in somewhat
more detail hereinbelow.
The advantages of the present invention can best be appreciated in
the context of the prior art as shown in FIGS. 2A and 2B. FIG. 2A
is a typical form of closure used in conjunction with plastic lined
containers. The drum top 16' is formed with a generally circular
lip 20' which terminates in an edge 26. In forming the prior art
rolled lip 20', the lip is so tightly rolled as to jeopardize the
integrity of the lining material on the rolled portion. Moreover, a
virtually inaccessible space within the rolled lip is formed which
space is extremely difficult to clean. Finally, edge 26, typically
bare steel at the outset of the fabricating process, is
substantially inaccessible to painting. The prior art closure of
FIG. 2A requires a specially fabricated gasket member 28, which is
expensive both to produce and to install, on the lip prior to
installation of closure member 24'. The outer periphery of closure
member 24' is provided with a rolled flange 30 which must be
carefully formed so that gasket 28 is compressed throughout a
substantial length.
FIG. 2B shows a known prior art structure that has been used with
tin plated drum materials. End panel 16" has a rolled lip 20" which
is substantially idetical to the 20' of FIG. 2A. Closure member 24"
has a rolled lip 30' in which there is formed, during fabrication
of the cover, a gasket 28'. The material of which gasket 28' is
formed is poured into the concave space defined by lip 30' and then
is raised to an elevated temperature to cure the same. Such
elevated temperature may exceed the safe temperature to which the
drum lining material can be elevated. In any event, the structure
of FIG. 2B suffers from the same disadvantages as that described in
connection with FIG. 2A in that an inaccessible unprotected edge
26' is formed and a concavity, difficult or impossible to clean, is
also formed.
The principle parts of the present invention are shown most clearly
in FIG. 3. In FIG. 3, it will be noted that lip 20 resides at an
acute angle, preferably about 45.degree., with the plane of end
wall 16. Lip 20 is formed by bending the material of which panel 16
is made on a relatively large radius bend 32. Such large radius
bend does not adversely affect the integrity of the plastic lining
material indicated at 34 in FIG. 3. Moreover, the concavity,
defined between the upper surface of wall 16 and the lower surface
of lip 20, is accessible to cleaning and painting as will appear in
more detail hereinafter. The closure member 24 includes a cylindric
mid-wall 36 which has an outer diameter sufficient for entry into
opening 18. At one end of cylindric mid-wall 36, the closure member
includes an integral circular wall 38 and at the opposite end of
the cylindric mid-wall is an outwardly extending annular flange 40.
The region between flange 40 and mid-wall 36 is formed at a
relatively large radius of curvature indicated at 42 so as to avoid
impairing the integrity of coating layer 44 on the closure
member.
An O-ring 22, having a relaxed radius corresponding to the radius
of curvature of portion 42, is provided. The diameter of the
central opening of the O-ring is preferably slightly less than the
outer diameter of cylindric mid-wall 36 so that the O-ring when
installed on closure member 24 will be retained in place thereon.
Any gasket which functions like an O-ring may be employed.
When drum 12 has been filled, closure 24 with O-ring gasket 22 in
place is inserted into opening 18. The closure member is moved
axially of the drum until the lower surface of flange 40 approaches
the outer edge of lip 20. Although FIG. 4 shows flange 40 in actual
contact with lip 20, such contact is not essential. Contact of
flange 40 with the outer edge of lip 20, however, limits the amount
of compression applied to O-ring 22 so as to avoid over compression
of the O-ring. With closure member 24 in the lowered or closed
position, a conventional tool (not shown) is introduced into the
hollow center of the closure member and activated to distort the
portion of cylindric mid-wall 36, thereby forming a re-entrant
region 46 which retains the closure member in place. A study of
FIG. 4 reveals several important advantageous characteristics of
the present invention. Note that O-ring 22 has been caused to
distort or "flow" because the O-ring is compressed between the
arcuate portion between flange 44 and mid-wall 36 of the closure
member and the upper surface of lip 20. Because the volume enclosed
is a generally triangular shape, there is space into which the
O-ring can flow. Thus, an extremely high quality seal is formed.
Moreover, the concavity between the lower wall of lip 20 and the
upper surface of drum wall 16 is accessible for cleaning, and if
desired, so also is the space between the lip 20 and flange 44.
In fabricating drum 12 and end wall 16 thereof, sheet material that
is coated on one side with plastic, film, tin, or the like layer 34
is cut and bent into shape. The method of manufacture includes
forming a circular opening in the end wall of the drum, said
opening being bounded by an unfinished edge and a margin of said
coating, and then bending the margin on an arcuate path to form the
frusto-conical lip 20 circumscribing the opening and diverging
therefrom. The bending step is performed so that the coating or
layer is exposed to the boundary of the opening and the opposite
surface of the lip resides at an acute angle relative to the end
wall to define a concavity. When lip 20 is formed (see FIG. 5), the
outer edge 48 as well as the lower surface 50 are bare steel. To
avoid rusting, such bare steel surfaces are painted, typically by a
spray painting apparatus indicated schematically at 52 in FIG. 6.
It can be seen that both edge 48 and surface 50, as well as the
upper surface of drum wall 16, are exposed to paint.
To avoid entry of paint to the interior of the drum, a temporary
plastic closure member 54 is provided. Temporary closure member 54
is typically molded of resilient material so that it can be snapped
into opening 18 before painting. The temporary closure member
includes an inwardly rolled lip 56 and an inwardly sloped wall 58
which is disposed at an angle so as to be in parallelism with lip
20. Below sloped wall portion 58 is a curved portion 60 which is
complemental to curved portion 32 of the lip. At the lower
extremity of curved portion 60 is a re-entrant projection 62 which
retains closure member 54 in place. Member 54 is completed by a
circular wall 64 which can have one or more perforations 66.
Perforations 66 permit movement of sufficient air through the cap
to avoid pressure build-ups within the drum while in the empty
condition that might otherwise dislodge the closure member.
After lip 20 is formed on drum wall 16, closure member 54 is
snapped in place as shown in FIG. 6 and painting of the bare metal
surfaces can proceed. Full paint coverage is achieved in the
concavity between lip 20 and the outer surface of panel 16 as well
as of edge 48 of the lip.
When the drum is to be filled, closure 54 is removed. The
foodstuffs or the like are then introduced through opening 18 and
closure member 24 is inserted and distorted to the position shown
in FIG. 4. At such position, the contents of the drum are exposed
only to the internal coated surfaces of the drum and closure member
and these surfaces are sealed to one another by the O-ring 22.
Furthermore, the concavity between the lip and the upper surface of
drum panel 16 is accessible for cleaning away of foodstuffs that
may have been inadvertently spilled during the filling process.
Moreover, the integrity of the film or tin lining interior of drum
12 is preserved because the curves used in forming the parts of the
closure member are of relatively large radius.
The inward movement of closure plug 24 in the embodiment of FIG. 3
is limited by contact of flange 40 with the outer edge of lip 20.
Although this structure operates quite satisfactorily, it requires
special care during formation of lip 20 to assure that the outer
edge thereof is coplanar with drum wall 16 in order that O-ring 22
be uniformly compressed throughout its circumference. The
embodiment of FIGS. 7-9 affords a different, and in some respects,
superior, technique for limiting the inward movement of the plug.
Because of the structural similarity between the embodiment of
FIGS. 1-7 and that of FIG. 3, similar characters of reference with
the addition of the reference letter a are employed for
corresponding parts. Thus, in the embodiment of FIGS. 7-9, there is
an end wall 16a in which is a circular opening 18a through which
the container is filled. Circumscribing opening 18a is a lip 20a
which forms an upwardly exposed frusto-conical surface 21, the
surface being lined with a layer 34a of suitable plastic material
or the like. An O-ring gasket 22a circumscribes a cylindric
mid-wall 36a of a closure plug 24a. The inner end of closure plug
24a has a circular end wall 38a which is integral with the
mid-wall. On the end of the closure plug opposite wall 38a, there
is a circular flange 40a that extends outward from mid-wall 36a.
Between the radial extremities of flange 40a is a downward
extending rib 41 which is radially spaced relative mid-wall 36a to
contact frusto-conical surface 21 (See FIG. 9). Thus, the rib 41
limits the inward position of plug 24a with respect to opening 18a.
Accuracy of the innermost position of the closure plug is important
to optimally compress O-ring gasket 22a so as to produce a
fluid-tight seal, without exceeding the elastic limit of the
material from which the O-ring is fabricated. Because rib 41 makes
surface contact with frusto-conical wall 21, accuracy of the
spacing in the embodiment of FIGS. 8 and 9 is not dependent on
accurately controlling the length of the lip 20a. Moreover, the
structure of FIGS. 8 and 9 is highly immune to damage.
It will be noted in FIG. 9 that, when rib 41 is in contact with
frusto-conical wall 21 and there retained by distortion of the
inner region of mid-wall 36a, indicated at 46a, a triangular-shaped
volume is formed by frusto-conical wall 21, the portion of flange
40a radially inward of rib 41 and the upper portion of mid-wall
36a. By proper dimensioning of the parts of the structure, the
sealing qualities of O-ring gasket 22a are optimally exploited by
compression within such triangular-shaped volume.
With reference to FIG. 7, it will be noted that wall 16a of the
container is formed with an annular reinforcing ring 70 which is
integral with top wall 16a and concentric with opening 18a. The
ring has oblique wall portions 72 and 74 which are oriented
obliquely of wall 16a so as to afford rigidity to the portion of
the wall that bounds opening 18a. Thus, when the closure plug is
moved to the closed position of FIG. 9, the likelihood of relative
movement between lip 20a and the closure plug is virtually
eliminated.
The embodiment of FIGS. 10 and 11 affords the advantages described
hereinabove in connection with FIGS. 3 and 4 and FIGS. 8 and 9.
Because of the structural similarity, reference characters with the
addition of a reference letter b are used to designated parts in
FIGS. 10 and 11 that correspond to the similar parts in FIGS. 3 and
4 and FIGS. 8 and 9. More specifically, the drum has a planar end
wall 16b from which extends, upward and outward, a lip 20b which
circumscribes an opening 18b. Lip 20b defines an upwardly exposed
frusto-conical wall 21b. A closure plug 24b has a generally
cylindric mid-wall 36b, at one end of which is a circular end wall
38b and at the opposite end of which is an annular flange 40b which
extends radially outward from the mid-wall. Mid-wall 36 at the
region thereof adjacent but spaced downward from flange 40b is
formed with a rib 41b which extends throughout the circumference of
the mid-wall and is uniformly spaced below the flange throughout
the periphery thereof. Before closure plug 24b is introduced into
opening 18b, an O-ring gasket 22b is placed around mid-wall 36b and
moved between flange 40b and rib 41b, as shown in FIG. 10. Rib 41b
is positioned so that it limits the inward travel of closure plug
24b by contact with frusto-conical wall 21b. Because the position
and configuration of rib 41b can be control-leg very accurately
with swaging techniques or the like, the innermost position of the
closure plug is accurately established. As can be seen in FIG. 11,
when mid-wall 36b is distorted outward, as at 46b, a triangular
volume is defined by frusto-conical wall 21b, the lower surface of
flange 40b and the portion of mid-wall 36b above rib 41b. The
magnitude of this volume can be precisely established to compress
O-ring gasket 22b within its elastic limits. It will be noted that
the outer extremity of flange 40b has a downwardly turned lip 74
which reinforces the flange and assists in excluding contaminates
from entering beneath the flange.
Thus, it will be seen that the present invention provides a closure
for a lined container which can be formed without adversely
affecting the integrity of the lining. Moreover, the closure member
is so constructed as to facilitate placement of protective coatings
on the surface of the material opposite that on which the lining is
present. The closure is so arranged that material, which might
accidentally be spilled on the exterior surface of the drum during
filling thereof can be completely removed. Finally, the closure is
configured so as to achieve an optimum O-ring seal so as to assure
freshness and cleanliness of the product contained in the drum.
Although several embodiments of the invention have been shown and
described, it will be obvious that other adaptations and
modifications can be made without departing from the true spirit
and scope of the invention. For example, while the invention has
been described with reference to a drum coated with plastic, film
or tin, it should be understood that it is not limited to use with
such drums.
* * * * *