Abstrict A desiccant cartridge for insertion into a laboratory desiccator
having a bowl with a side wall, a concave bottom wall, a plurality
of spaced projections within the side wall located proximate the
concave bottom wall, a shelf supported on the projections, and a
space between the shelf and the concave bottom wall, the desiccant
cartridge having a convex bottom wall and a planar perforated top
wall joined by a seam, a plurality of circumferentially spaced indentations
in the cartridge for placement in mating relationship with the projections,
and desiccant confined between the bottom and top walls, the desiccant
cartridge being located in the space below the shelf with its convex
bottom wall in contiguous relationship to the concave bottom wall
of the bowl and with its top wall being spaced from the shelf.
Claims What is claimed is:
1. A desiccant cartridge comprising a bottom wall having upwardly
extending outer side portions, a substantially planar circular top
wall, openings in said top wall for permitting passage of a gas,
a plurality of circumferentially spaced recessed portions in said
outer side portions, desiccant confined between said walls, a first
edge portion of said outer side portions, a second edge portion
on said top wall, a seam joining said first and second edge portions,
and second circumferentially spaced recessed portions in said planar
top wall in alignment with said recessed portions in said outer
side portions.
2. A desiccant cartridge as set forth in claim 1 wherein said bottom
wall is fabricated from flexible cloth-like material and wherein
said desiccant is packed sufficiently loosely so that manipulation
of said bottom wall can result in moving said desiccant within said
cartridge to cause different portions of said desiccant to be located
adjacent said top wall.
3. A desiccant cartridge as set forth in claim 1 wherein said top
wall is fabricated of material which is sufficiently stiff so as
to retain its substantially planar shape.
4. A desiccant cartridge as set forth in claim 3 wherein said openings
are in the form of perforations.
5. A desiccant cartridge as set forth in claim 3 wherein said bottom
wall is fabricated from flexible cloth-like material and wherein
said desiccant is packed sufficiently loosely so that manipulation
of said bottom wall can result in moving said desiccant within said
cartridge to cause different portions of said desiccant to be located
adjacent said top wall.
6. A desiccant cartridge as set forth in claim 5 wherein said bottom
wall is porous.
7. In a laboratory desiccator having a bowl with a side wall, a
bottom wall, a shelf having an upper side and an underside, a plurality
of circumferentially spaced projections located proximate said bottom
wall for supporting said underside of said shelf thereon, and a
space between said shelf and said bottom wall for receiving desiccant
material, the improvement comprising a desiccant cartridge comprising
a cartridge bottom wall positioned in said space in contiguous relationship
to said bottom wall of said bowl, outer upwardly extending side
portions on said cartridge bottom wall, a substantially planar circular
top wall spaced from said underside of said shelf, a plurality of
circumferentially spaced recessed portions in said outer side portions
for receiving said projections in mating relationship, desiccant
confined between said top wall and said cartridge bottom wall, and
openings in said top wall for effecting communication between said
desiccant and said space between said underside of said shelf and
said top wall.
8. In a laboratory desiccator as set forth in claim 7 including
second recessed portions in said top wall in alignment with said
recessed portions.
9. In a laboratory desiccator as set forth in claim 7 wherein said
bottom wall is fabricated of porous material.
10. In a laboratory desiccator as set forth in claim 7 wherein
said openings are in the form of perforations.
11. In a laboratory desiccator as set forth in claim 7 including
a first edge portion on said outer side portions, a second edge
portion on said top wall, and a seam joining said first and second
edge portions.
12. In a laboratory desiccator as set forth in claim 11 wherein
said cartridge bottom wall is fabricated from flexible cloth-like
material and wherein said desiccant is packed sufficiently loosely
so that manipulation of said cartridge bottom wall can result in
moving said desiccant within said cartridge to cause different portions
of said desiccant to be located adjacent said top wall.
13. In a laboratory desiccator as set forth in claim 12 wherein
said cartridge bottom wall is porous.
14. In a laboratory desiccator as set forth in claim 11 wherein
said top wall is fabricated of material which is sufficiently stiff
so as to retain its substantially planar shape.
15. In a laboratory desiccator as set forth in claim 14 wherein
said top wall is also flexible.
16. In a laboratory desiccator as set forth in claim 14 wherein
said cartridge bottom wall is fabricated from flexible cloth-like
material and wherein said desiccant is packed sufficiently loosely
so that manipulation of said cartridge bottom wall can result in
moving said desiccant within said cartridge to cause different portions
of said desiccant to be located adjacent said top wall.
17. In a laboratory desiccator as set forth in claim 14 wherein
said cartridge bottom wall is porous.
Description BACKGROUND OF THE INVENTION
The present invention relates to a desiccant cartridge for a laboratory
desiccator.
By way of background, there are in use laboratory desiccators which
include a glass bowl having spaced projections on the lower internal
surface thereof for supporting a shelf onto which material to be
desiccated is placed. A space is provided below the shelf for receiving
desiccating material. In the past the desiccating material was dumped
in bulk into the desiccating-receiving space. This was objectionable
for a number of reasons. First of all, dust, which was generated
as a result of pouring the bulk desiccant, settled onto the sealing
lip of the desiccator bowl and thus interfered with proper sealing
when the desiccator cover was installed. In addition, if too much
desiccant was used, it would extend above the projections so that
the shelf would not sit level, and if the shelf touched the top
of the desiccant, it blocked the desiccating action to some extent.
If too little desiccant was used, the desiccating capacity was diminished.
In addition, since the desiccant touched the inside surface of the
lower portion of the bowl, there was no space between the desiccant
and the side of the bowl so that practically the only desiccating
effect was obtained through the top of the desiccant. Additionally,
handling of bulk desiccant was time-consuming and messy. It is with
overcoming the foregoing deficiencies of prior art laboratory desiccators
that the present invention is concerned.
SUMMARY OF THE INVENTION
It is accordingly one object of the present invention to provide
a desiccant cartridge for a laboratory desiccator so that there
is no need to utilize bulk desiccant.
Another object of the present invention is to provide a desiccant
cartridge for a laboratory desiccator which provides an exactly
measured amount of desiccant and which has its top portion spaced
from the shelf in the desiccator so that the top of the desiccant
cartridge is completely unobstructed.
A further object of the present invention is to provide a desiccant
cartridge for a laboratory desiccator which is shaped to fit around
the projections in the desiccator, thereby providing maximum utilization
of the desiccant-receiving space, notwithstanding that the desiccant
is confined within the walls of a cartridge.
Yet another object of the present invention is to provide a desiccant
cartridge for a laboratory desiccator in which the desiccant is
packed relatively loosely and the bottom wall of the desiccant cartridge
is flexible so that the bottom wall can be manipulated to reposition
the desiccant within the cartridge to thereby remove saturated desiccant
from the area near the top of the cartridge and reposition unsaturated
desiccant in that area.
Still another object of the present invention is to provide a desiccant
cartridge for a laboratory desiccator in which the bottom wall of
the cartridge is fabricated from porous material which may be spaced
from the bottom of the laboratory desiccator so that there can be
a desiccating action therethrough. Other objects and attendant advantages
of the present invention will readily be perceived hereafter.
The present invention relates to a desiccant cartridge comprising
a bottom wall having upwardly extending outer side portions, a substantially
planar circular top wall, openings in said top wall for permitting
passage of a gas, a plurality of circumferentially spaced recessed
portions in said outer side portions, and desiccant confined between
said walls.
The present invention also relates to an improvement in a laboratory
desiccator having a bowl with a side wall, a bottom wall, a shelf
having an upper side and an underside, a plurality of circumferentially
spaced projections located proximate said bottom wall for supporting
said underside of said shelf thereon, and a space between said shelf
and said bottom wall for receiving desiccant material, the improvement
comprising a desiccant cartridge comprising a cartridge bottom wall
positioned in said space in contiguous relationship to said bottom
wall of said bowl, outer upwardly extending side portions on said
cartridge bottom wall, a substantially planar circular top wall
spaced from said underside of said shelf, a plurality of circumferentially
spaced recessed portions in said outer side portions for receiving
said projections in mating relationship, desiccant confined between
said top wall and said cartridge bottom wall, and openings in said
top wall for effecting communication between said desiccant and
said space between said underside of said shelf and said top wall.
The various aspects of the present invention will be more fully
understood when the following portions of the specification are
read in conjuction with the accompanying drawings wherein:
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a top plan view of the desiccant cartridge of the present
invention;
FIG. 2 is a bottom plan view, partially broken away, of the desiccant
cartridge of the present invention;
FIG. 3 is a fragmentary enlarged cross sectional view taken substantially
along line 3--3 of FIG. 1;
FIG. 4 is a fragmentary view, partially broken away, of a laboratory
desiccator containing the desiccant cartridge of the present invention;
FIG. 5 is a fragmentary cross sectional view taken substantially
along line 5--5 of FIG. 4; and
FIG. 6 is a cross sectional view taken substantially along line
6--6 of FIG. 5 and showing parts of the laboratory desiccator and
its contents broken away and at different elevations.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The improved desiccant cartridge 10 of the present invention includes
a convex bottom wall 11 fabricated from porous polyester felt material
and having a plurality of circumferentially spaced recessed portions
12 therein which are formed by a suitable pressing operation. The
concave bottom wall includes a lowermost portion 13 which merges
into upwardly curved outer side portions 14 between recessed portions
12.
The desiccant cartridge also includes an upper substantially planar
wall 15 which is fabricated from a relatively stiff, yet flexible,
material, such as sheet Mylar film. The wall 15 contains openings
18 in the form of perforations which are preferably about 0.062
inches in diameter and comprise a very high percentage of the total
area of top wall 15. The openings 18 can take any other form which
will permit gases to pass through top wall 15. Top wall 15 also
includes a plurality of circumferentially spaced recessed portions
16 which are in alignment with recessed portions 12 of bottom wall
11. Top wall 15 is secured to bottom wall 13 by a seam 17 which
is formed as a lap joint of edge portion 19 of lower wall 11 secured
to edge portion 20 of upper wall 15. The securing may be by any
suitable attachment technique which is preferably ultrasonic welding,
or may be electrostitching or any other suitable mode of connection
including gluing, stitching and the like. The edge portion 19 of
bottom wall 11 includes three edge portions 19' which are connected
by short edge portions 18' (FIG. 2). The edge portion 20 of top
wall 15 includes three edge portions 20' which are connected by
edge portions 28.
The chamber 21 formed between upper wall 15 and lower wall 11 is
preferably loosely filled with silica gel beads but may be packed
firmly, if desired. The beads are preferably of the type known as
indicating silica gel beads which are blue before they absorb moisture
and turn pink after they absorb moisture, thereby indicating the
condition of the desiccant. When indicating beads are used, it is
preferred that top wall 15 be transparent. Other desiccants, such
as molecular sieve, clay, calcium oxide, calcium sulphate, etc.
may be used.
As noted briefly above, the desiccant cartridge 10 is for use in
a laboratory desiccator 24 which includes a glass lower bowl portion
25 having a generally cylindrical upper portion 26 terminating at
ground lip 27 and a lower portion 30 which is curved as generally
shown in cross section in FIG. 5. A circular foot 31 is located
at the lowermost portion of bowl 25 and located within the foot
31 is a dished bottom wall 32 having an inner concave or dished
surface 33. A glass cover 34 is provided having a ground edge lip
35 which is adapted to be placed in sealing engagement with lip
27 after a sealing grease layer is placed therebetween. Cover 34
includes the aspirating tube 36 which is attached to cover portion
37 through which the inside of the laboratory desiccator may be
exhausted by the use of a suitable vacuum source.
The laboratory desiccator 24 includes a plurality of projecions
39 which are circumferentially spaced at 120.degree. intervals along
the inside surface 40 of bowl portion 30. Projections 39 terminate
at an upper shelf portion 41 which support a perforated ceramic
shelf which supports material to be treated within the desiccator
24.
As stated briefly above, in the past the space underneath shelf
42 was filled with loose desiccant pellets. If the space was filled
too full, shelf 42 would not rest squarely on shelf surfaces 41
and therefore the items placed on shelf 42 might not stand properly.
If the space between shelf 42 was not filled full enough, an insufficient
desiccating effect might be obtained or the desiccant would have
to be replaced more frequently. In either event the desiccant dust
produced as a result of filling the desiccator would settle on lip
27 and would oppose the establishing of a good seal between it and
lip 35. Furthermore, if shelf 42 rested on the desiccant pellets,
the solid portions of shelf 42 would block the desiccant from acting
effectively since the only way there could be communication between
chamber 43 above shelf 42 and the desiccant would be through the
perforations 44 and the spaces 45 and central perforation 46. In
other words, there would not be the unhampered communication from
chamber 43 to the entire surface of the desiccant beads below shelf
42.
The desiccant cartridge of the present invention is intended to
fit as shown in FIGS. 4 5 and 6 with the recessed portions 12:16
of the cartridge 10 in mating engagement with the outer side surfaces
47 of projections 39 (FIG. 6). By having the recessed portions of
cartridge 10 mate with the projections 39 the space below shelf
42 can be filled to the fullest extent, thereby providing a high
desiccating capacity, especially considering that the lower wall
11 of the desiccant cartridge is located in contiguous relationship
to the inner surface 33 of dished bottom wall 32 of bowl 25. The
upper wall 15 of the desiccant cartridge is located so that a clearance
space 49 exists between it and the undersurface 50 of shelf 42
thereby providing for good circulation between the space 43 above
shelf 42 and the top 15 of the cartridge. Top wall 15 is sufficiently
stiff so that it will oppose rotary motion of the cartridge 10
thereby maintaining it in position. Furthermore, the relative stiffness
of top 15 will cause it to retain its substantially planar shape,
thereby preventing it from contacting the undersurface 50. This
prevents destruction of the top wall in the event extremely hot
items are placed on shelf 42. While the stiffness of top wall 15
is very desirable, it will be appreciated that it need not be stiff,
as it can be straightened to a planar condition, if desired, after
installation if it is not stiff.
As noted briefly above, the desiccant beads 22 are preferably loosely
packed between walls 11 and 15. Thus, after the upper surface of
the beads becomes saturated, as will be indicated by their turning
pink if the indicating silica gel beads are used, the lower wall
11 can be manipulated so as to cause the beads in the central portion
and at the bottom of the cartridge to be moved up closer to top
wall 15 thereby in essence exposing fresher unused beads for desiccating
use.
Furthermore, the bottom wall 11 is porous and there are some gaps
between it and the inner portions of bowl 26 contiguous thereto
so that a certain amount of desiccating action will occur through
this wall also, whereas with the loose beads, this was not possible
in view of the fact that the outer layer of the beads was in full
contact with the inner surface of the bowl. If desired, spacers
(not shown) may be located between cartridge bottom wall 11 and
inner concave surface 33 so that a greater desiccating effect may
be obtained by exposing a greater area of bottom wall 11 through
which desiccating action can occur because of the porous nature
of bottom wall 11. These spacers may take the form of cylindrical
plastic buttons about 1/2 inch in diameter and about 1/4 inch high,
the bases of which are suitably secured at spaced intervals to the
outer surface of bottom wall 11.
The specific cartridge shown in the drawings has the following
parameters. Top 15 is approximately 9.25 inches in diameter and
cartridge 10 is approximately 2.0 inches high. It contains 3.25
pounds of silica gel beads. The Mylar polyester top 15 is approximately
0.014 inches thick. The felted polyester bottom wall is normally
0.050 inches thick and weighs 10 ounces per square yard. The seam
17 is approximately 0.125 inches wide. The perforations in top wall
15 are 0.062 inches in diameter and are positioned in parallel rows
spaced about 0.200 inches from each other and the perforations within
the rows are also spaced about 0.200 inches from each other. It
is to be noted that the parallel rows of perforations 18 extend
throughout the top wall 15 notwithstanding that only a portion
of the perforations are shown in FIGS. 1 and 6 for ease of illustration.
The foregoing parameters are by way of illustration and it will
be appreciated that they can be varied within the scope of the present
invention.
While bottom wall 15 has been described as porous, it will be understood
that this term includes any type of openings through which gases
may pass to the inside of cartridge 10 and which will prevent passage
of desiccant therethrough.
While a preferred embodiment of the present invention has been
disclosed, it will be appreciated that the present invention is
not limited thereto but may be otherwise embodied within the scope
of the following claims. |