U.S. patent number 3,735,551 [Application Number 05/210,055] was granted by the patent office on 1973-05-29 for apparatus for and method of packaging with gas flushing.
This patent grant is currently assigned to Pratt Manufacturing Corp.. Invention is credited to Robert H. Pratt.
United States Patent |
3,735,551 |
Pratt |
May 29, 1973 |
APPARATUS FOR AND METHOD OF PACKAGING WITH GAS FLUSHING
Abstract
Upper and lower web portions of sealable material are
continuously fed and guided, while products which are to be
packaged are delivered in longitudinally spaced relationship
therebetween. There is skip-sealing means for sealing the web
together on at least one side edge while leaving unsealed side gas
outlets at regular intervals. Gas injecting means which extends
between the webs has a discharge end located a substantial distance
downstream of the skip-sealing means, and there is a cross sealer
immediately downstream of the outlet end of the gas injecting
means. A first set of soft pressure rolls downstream of the cross
sealer presses the webs against the product and exhausts gas and
air from the side gas outlets, there being a second set of soft
pressure rolls between the cross sealer and skip-seal wheel forming
a dam against further upstream travel of the gas, to confine the
gas travel to a distance equal to less than the length of one
package. Downstream of the first set of pressure rolls there is
means for sealing the gas outlets, and there is a cut-off knife for
transversely severing the packages at the cross seals.
Inventors: |
Pratt; Robert H. (Milwaukee,
WI) |
Assignee: |
Pratt Manufacturing Corp.
(Milwaukee, WI)
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Family
ID: |
22781423 |
Appl.
No.: |
05/210,055 |
Filed: |
December 20, 1971 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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69301 |
Sep 8, 1970 |
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Current U.S.
Class: |
53/433; 53/511;
53/450; 53/553 |
Current CPC
Class: |
B29C
66/81433 (20130101); B29C 66/8161 (20130101); B29C
66/432 (20130101); B29C 66/83413 (20130101); B29C
66/83513 (20130101); B29C 66/82261 (20130101); B29C
66/1122 (20130101); B29C 66/849 (20130101); B29C
66/0326 (20130101); B29C 66/3452 (20130101); B29C
65/18 (20130101); B29C 66/8221 (20130101); B65B
31/04 (20130101); B29C 66/81465 (20130101); B29C
66/4312 (20130101); B29C 66/8226 (20130101); B29C
66/8222 (20130101) |
Current International
Class: |
B29C
65/18 (20060101); B29C 65/00 (20060101); B65B
31/04 (20060101); B65b 031/00 () |
Field of
Search: |
;53/22A,112A |
References Cited
[Referenced By]
U.S. Patent Documents
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2951324 |
September 1960 |
Podlesak et al. |
3009298 |
November 1961 |
Gerlach et al. |
|
Primary Examiner: McGehee; Travis S.
Parent Case Text
This application is a continuation-in-part of application Ser. No.
069,301, filed Sept. 8, 1970, now abandoned.
Claims
What I claim is:
1. In packaging apparatus having means for continuously advancing
web portions of sealable packaging material, having means for
feeding goods in longitudinally spaced relationship between said
web portions, having means for continuously forming the packaging
material into an elongated tube having at least one set of
longitudinal edges which must be longitudinally sealed together,
the improvement comprising skip sealing means for sealing said
edges while leaving unsealed gas outlets at longitudinally spaced
intervals, a gas injecting tube extending into the elongated tube
and having a discharge end located a substantial distance
downstream of the skip sealing means, a cross sealer downstream of
the discharge end of the gas injecting tube, longitudinally spaced
transversely extending pressing means continuously engageable with
the web portions in longitudinally spaced transverse locations, one
of which is downstream of the discharge end of the gas injecting
tube and the other of which is upstream thereof to form a dam
against upstream travel of the gas whereby it is exhausted from an
unsealed gas outlet, and means downstream of said pressing means
for sealing said gas outlets.
2. Packaging apparatus as claimed in claim 1 in which the set of
longitudinal edges which must be sealed together is at a side of
the advancing web portions and in which the skip sealing means is
located at said side.
3. Packaging apparatus as claimed in claim 1 in which the pressing
means comprises longitudinally spaced transversely extending sets
of pressure rolls.
4. Apparatus as claimed in claim 1 in which there is an upper and
lower web portion which must be longitudinally sealed together on
opposite sides, and in which there is skip sealing means on both
sides of the web portions.
5. Packaging apparatus as claimed in claim 1 in which the skip
sealing means is a pair of heat sealing wheels having peripheral
cutouts.
6. Apparatus as claimed in claim 4 in which there is a pair of heat
sealing wheels engageable with each side of the advancing web
portions, each pair of wheels having peripheral cutouts.
7. Apparatus as claimed in claim 1 in which the means for sealing
the gas outlets comprises a pair of sealing wheels having
peripheral projections positioned to engage the unsealed
longitudinal edge portions of the webs therebetween.
8. Apparatus as claimed in claim 4 in which the means for sealing
the gas outlets comprises a pair of heat sealing wheels on each
side of the advancing web portions having peripheral projections
positioned to engage the unsealed longitudinal edge portions of the
webs therebetween.
9. Apparatus as claimed in claim 1 in which the spacing between the
pressing means is less than the distance between cross seals.
10. In a method of packaging the steps of continuously advancing
web portions of sealable packaging material, feeding goods in
longitudinally spaced relationship between said web portions,
continuously forming the packaging material into an elongated tube
having at least one set of longitudinal edges which must be
longitudinally sealed together, sealing said edges while leaving
temporarily unsealed gas outlets at longitudinally spaced
intervals, injecting a gas into the tube at a predetermined
location downstream, intermittently cross sealing the tube,
pressing the tube against the goods at longitudinally spaced
transverse locations one of which is downstream of the place of gas
injection and one of which is upstream thereof to form a dam
limiting upstream travel of the gas and to cause the gas to be
exhaused from the unsealed gas outlets, and thereafter sealing the
gas outlets.
11. A method of packaging as claimed in claim 10 in which the cross
sealing of the web portions is performed in a location between said
two pressing locations and downstream of the place of gas
injection.
12. A method of packaging as claimed in claim 10 in which the
advancing web portions are arranged so that one forms an upper and
one a lower web portion and in which the set of longitudinal edges
to be longitudinally sealed together is at a side of the advancing
web portions and in which the sealing is performed at said
side.
13. A method of packaging as claimed in claim 12 in which there are
two sets of longitudinal edges one on each side of the advancing
web portions which must be longitudinally sealed together and in
which the step of sealing while leaving temporarily unsealed gas
outlets at longitudinally spaced intervals is performed on both
sides.
14. A method of packaging as claimed in claim 11 which includes the
step of transversely severing the packages where they have been
cross sealed after the sealing of the gas outlets has been
accomplished.
15. Packaging apparatus as claimed in claim 1 in which the skip
sealing means includes a pair of sealing wheels, and also includes
means for moving at least one of said sealing wheels to an
inoperative position at regular intervals to leave the unsealed gas
outlets at the longitudinally spaced intervals.
16. Packaging apparatus as claimed in claim 15 in which the means
for moving a wheel to inoperative position is cam operated.
17. Packaging apparatus as claimed in claim 1 in which the skip
sealing means includes sealing shoes normally in sealing position
with said longitudinal edges, and also includes pivotally supported
means for moving at least one of said sealing shoes to inoperative
position at regular intervals to provide the unsealed gas outlets
at longitudinally spaced intervals.
18. Packaging apparatus as claimed in claim 17 in which the means
for moving a shoe to inoperative position is cam operated.
19. Packaging apparatus as claimed in claim 17 in which there are
upper and lower transverse rock shafts above and below the web
portions, in which there are shoe supporting levers supported on
said rock shafts, and in which the upper and lower rock shafts are
geared to each other to provide for conjoint movement of both the
upper and lower shoes into and out of engagement with the web
portions.
20. Packaging apparatus as claimed in claim 1 in which the skip
sealing means is a pair of heat sealing wheels having a regular
skip seal pattern thereon.
21. Packaging apparatus as claimed in claim 1 in which said skip
seal pattern comprises spaced, transversely and obliquely extending
peripheral grooves.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention pertains to the continuous packaging in
sealable material, such as transparent film, of perishable items
such as meat, cheese, or the like where the shelf life is increased
by use of an inert gas which replaces air in the package or to the
packaging of disposable items or devices which must be maintained
in sterile condition prior to use.
2. Description of the Prior Art
Heretofore various types of apparatus have been proposed for gas
packing food products such as cheese. Most of the prior
apparatuses, however, relate to entubing of the product in a tube
of packaging material having a top or bottom fin seal produced by
apparatus such as that of the expired Campbell U.S. Pat. No.
2,882,662. With these prior methods the gas has been discharged
into the tube a substantial distance downstream of the package
former, and has been caused to travel upstream out of the open end
of the tube of packaging material. Such an arrangement is typical
of the apparatus of the Podlesak U.S. Pat. No. 2,919,990, and the
arrangement of the expired Maxfield U.S. Pat. No. 2,160,367 is
similar to that of Podlesak except that, in Maxfield, the gas tube
is shorter and the gas travels the length of a single package only.
Likewise in the Gerlach U.S. Pat. No. 3,009,298 the gas injection
nozzle extends a substantial distance downstream from the former
and is caused to react on blocks of food material being wrapped in
a tube with a continuous bottom fin seal. One of the embodiments of
the Maxfield patent discloses a package having a single side seal,
but in this patent there is a complicated former tube or mandrel
having a special duct arrangement therein for admitting and
exhausting the preservative gas. All of these prior patents exhaust
the gas from the open end of the tube being formed.
SUMMARY OF THE INVENTION
The present invention provides a novel apparatus and method for
gas-packaging items in a package having longitudinal edge portions,
usually at one or both sides of the package, which are to be sealed
together, wherein there is simple means for controlling the exhaust
of air and gas from longitudinally spaced, temporarily unsealed
lengths of said edge portions.
A further object of the invention is to provide, as a preferred
embodiment, a novel method of packaging products in packages having
heat seals along both sides wherein longitudinally spaced,
temporarily unsealed gas outlets are employed along both sides.
A further object of the invention is to provide improved apparatus
for effecting commercial exploitation of the improved method.
A further object of the invention is to provide a method and
apparatus which replaces air in the package with a gas while
pressing the packaging material against the product and while
providing a simple way of exhausting air and gas.
A further object of the invention is to provide an improved
apparatus for packaging products which is relatively inexpensive to
construct, which is efficient in operation, and which is well
adapted for the purposes described.
With the above and other objects in view, the invention consists of
the improved apparatus for and method of packaging products, and
all of its parts, combinations, and steps, as set forth in the
claims, and all equivalents thereof.
BRIEF DESCRIPTION OF THE DRAWINGS
In the accompanying drawings, illustrating one complete embodiment
of apparatus for carrying out the invention:
FIG. 1 is a plan view, partially diagrammatic, of the
apparatus;
FIG. 2 is an edge view thereof;
FIG. 3 is a transverse sectional view showing a modification;
FIG. 4 is a fragmentary view similar to part of FIG. 2 showing
another modification;
FIG. 5 is a fragmentary plan view, partially diagrammatic, showing
still another modification;
FIG. 6 is an edge view of the modification of FIG. 5;
FIG. 7 is an edge elevational view of still another
modification;
FIG. 8 is a fragmentary plan view showing part of the modification
of FIG. 7;
FIG. 9 is a fragmentary plan view of an edge of the web showing the
type of seal produced by the modification of FIGS. 7 and 8; and
FIG. 10 is a fragmentary elevational view showing the sealing
members of the form of the invention of FIGS. 7 and 8.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring more particularly to FIGS. 1 and 2 of the drawings, the
numeral 10 designates a suitable conveyor for continuously
advancing items 11 which are to be packaged. The items 11 may be
cheese, sliced meat, or other material, or may be disposable items
or devices which must be kept sterile prior to use, and are
preferably of the type that can be packaged in a relatively flat
package having one or more longitudinal seals, which seals are
usually at the sides of the package. Webs of suitable heat-sealable
packaging material 12 are fed from a suitable source of supply into
a former 13 of the type shown more particularly in FIG. 4 of U.S.
Pat. No. 2,982,066 and having an outlet slot 14. While the drawing
illustrates two separate webs being fed into a former of the type
illustrated, which webs must be sealed on both sides, it is to be
understood that the invention can be carried out as shown in FIG. 3
where a single web has a fold 40 along one side and where sealing
has to be done only on the opposite side of the package. The
packaging material may be a thin sheet of polypropylene or
polyethylene which is inherently heat-sealable, but it may be some
other material locally coated with polypropylene or other sealable
material or material having areas sealable by pressure either with
or without heat.
Extending into opposite sides of the former from a suitable source
of an inert or other gas under pressure, of a type which is useful
in increasing the shelf life of food products, such as nitrogen or
CO.sub.2, or of a type which is adapted to sterilize items or
devices, such as ethylene oxide gas, are gas tubes 15 which are
bent to extend longitudinally of the traveling web, and are located
between the product and the sides of the package, as illustrated in
FIG. 1. The discharge ends 16 of the gas tubes are a substantial
distance downstream from the former. Immediately downstream of the
former are upper and lower side skip-seal wheels 17, engageable
with the web at one side of the packages being formed and, in the
preferred embodiment, upper and lower side skip-seal wheels 18
engageable with the web at the other side. These wheels are
supported on upper and lower shafts 19 and 20 which are suitably
journaled. In the preferred embodiment the wheels 17 and 18 are
suitably heated in any well-known manner to perform such heat
sealing. Where certain other types of material are used for the
webs heat sealing may not always be necessary. As a novel feature
of the present invention the sealing wheels 17 and 18 are formed
with peripheral cutouts 21 which are 180.degree. apart on each
wheel. As the webs advance, the heat sealing wheels 17 and 18 heat
seal the side edges of the package as at 22, but at regularly
spaced intervals the cut-outs 21 in the heat sealing wheels leave
temporarily unsealed gas discharge outlet openings 23. The diameter
of the skip-sealing wheels 17 and 18 is such that there is an
unsealed gas discharge outlet 23 on each side for each package
length (referring to the length of the packages 26). The diameters
of the skip-sealing wheels 17 and 18 and the location of the
cut-outs 21 are such as to provide the gas outlets near the
trailing end of the product in each package. This allows the gas to
be forced along the product 11 to act on all portions thereof
before it reaches the gas outlets.
Between the discharge ends 16 of the gas tubes and the side
skip-seal wheels 17 and 18 is a first pair of soft rolls 24 which
serve to press the web material against the packaged product 11.
These soft rolls 24 also form a dam against the movement of gas or
air any further upstream. A second set of soft rolls 25 are
suitably supported for rotation above and below the web downstream
of the first set of rolls. The spacing between the sets of rolls 23
and 24 is slightly less than the length of one of the completed
packages 26 and slightly less than the spacing between cross seals
29.
Positioned midway between the sets of rolls 24 and 25 are upper and
lower cross sealing bars 27. These are suitably supported for
intermittent movement into cross sealing relationship, and are
suitably equipped with heating elements 28 to form the cross seals
29 between packages. One method of operating cross sealing bars is
disclosed in FIG. 11 of Thompson U.S. Pat. No. 2,982,066.
Downstream of the soft rollers 25 are additional sets of side
sealing wheels 30 and 31. These wheels have only short peripheral
suitably heated sealing portions 32 which are 180.degree. apart.
The wheels are suitably supported on cross shafts 33 and 34 and are
driven in suitably timed relationship so that the peripheral
projections 32 engage opposite sides of the packaging material at
the unsealed gas discharge openings 23 to seal said portions.
Thereafter the packages may pass through a pair of suitably driven
pull rolls 35, and downstream thereof are upper and lower cut-off
knives 36 of any well-known type such as those shown in FIGS. 17 to
21 of U.S. Pat. No. 2,982,066, which will act to intermittently
engage the transversely sealed portions 29 to sever the packages 26
one from another.
In carrying out the method with the improved apparatus, the
material 11 which is to be packaged is fed in spaced relationship
in line formation into the former 13 between the moving webs 12.
The upper and lower webs are heat sealed at the sides by the side
skip-seal wheels 17 and 18 leaving side gas discharge openings 23.
Gas which is being continuously discharged from the ends 16 of the
gas tubes is always confined between the sets of soft rollers 23
and 24, as the rollers 24 serve as a dam to prevent upstream
movement of the gas any further toward the open end of the tube of
packaging material. At the same time the soft rollers 25 are
continuously pressing the packaging material against the product
and causing limited upstream movement of the gas. Inasmuch as this
gas, together with the air in the package, is blocked from movement
upstream past the rollers 24, it will, whenever a set of side gas
discharge openings 23 passes downstream beyond the rollers 24, be
discharged from said side outlets 23. As before noted, the side gas
outlets are located at the trailing ends of the product 11 within
each package portion so that all portions of the product are
exposed to the action of the gas before the gas is discharged from
the outlets 23. It will be noted from FIG. 1 that the gas outlets
23 which are below the pressing rolls 25 are just in advance of the
transverse seal 29 at the end of a package. A limited amount of the
inert gas will remain in each package, principally between the
borders of the product and the package seals. Thereafter the side
seal wheels 30, with the short sealing projections 32, will heat
seal the gas discharge openings 23 to completely seal the package.
The packages are then severed, one from another, by the cut-off
knives 36 as is well known in the art.
In the modification of FIG. 4 the same reference numerals are
applied to corresponding parts as are used in FIG. 1 except that
the numerals are in a 200 series. Here the only change in
construction is in conjunction with the sealing wheels 218 and
218'. Instead of having the skip-seal notches 21 of the form of the
invention of FIG. 1, the peripheries of the wheels 218 and 218' are
continuous. The wheels 218' are mounted on a shaft 220 which shaft
is journalled in suitable bearings. The wheels 218' are in
continuous contact with the lower web 212. The upper shaft 219 is
journalled in bearings 250, one on each side, which are supported
on the upper ends of movable supports 251, each support 251 having
a large opening 252 through which the shaft 220 for the lower
wheels can pass, the opening 252 providing sufficient clearance
around the shaft 220 to permit up-and-down movement of the bearing
support 251. The lower end of each support 251 has a cam follower
roller 252 for coaction with a suitably supported and driven cam
253 having a high portion 254. The upper wheels 218 are the sealing
wheels and are heated by any suitable heating means such as the
electric heating elements 255.
In use of this modification of FIG. 4 the operation is the same as
heretofore described in connection with FIG. 1 except that the
unsealed gas discharge openings which correspond to the openings 23
of FIG. 1 are produced by having the high portions of the cams 254
so timed as to cause the upper heated sealing wheels 218 to be
temporarily raised out of contact with the upper web 212, at
regular intervals and for a sufficient length of time to produce
gas discharge openings corresponding to the gas discharge openings
23 of FIG. 1, and located in the same manner relative to the
package being formed. Thus the timing in the apparatus of FIG. 1 is
such that one set of gas discharge openings such as the openings 23
of FIG. 1 is produced on each side for each package length, and
these outlet openings are preferably near the trailing end of the
product in each package, as heretofore illustrated and described in
connection with FIG. 1. This allows the gas to be forced along the
product 211 to act on all portions thereof before the gas reaches
the gas outlets at the sides of the package. All of the mechanism
after the sealing wheels of FIG. 4 is the same as has been
illustrated in FIGS. 1 and 2, including the use of wheels such as
the wheels 31 having short sealing portions such as the sealing
portions 32 of FIG. 2 for engagement with opposite sides of the
packaging material at the unsealed gas discharge openings to
finally seal said openings.
In the modification of FIGS. 5 and 6 all of the corresponding parts
are designated by the same numerals used in FIGS. 1 and 2 except
that they are in a 300 series. In this form of the invention,
instead of the sealing wheels used in the form of the invention of
FIGS. 1 and 2, there are continuously surfaced pressure wheels 318
which are not heated but which apply sealing pressure after the
material has been heated by shoe heaters 360. The lower shoe heater
on each side is mounted on one end of a lever 361 which pivots with
a suitably journaled rock shaft 362. The levers 361 project beyond
the shaft 362 and carry cam follower rollers 363 which coact with
suitably-supported and driven cams 364. Also mounted fast on the
shaft 362 are gears 365.
Each upper shoe 360 is mounted on the forward end of a lever 366,
the latter being rigidly secured to a suitably supported upper rock
shaft 367, said shaft having gears 368 rigid thereon and meshing
with the lower gears 365. Suitably supported springs 369 normally
exert an upward pull on the ends of the levers 366.
In the form of the invention of FIGS. 5 and 6, after the web
portions 312 leave the former 313, both side edges are acted upon
by the heated sealing shoes 360 which are normally together and in
sealing position. However, whenever the high portions of the cams
364 engage the cam followers 363, the shoes 360 are temporarily
separated, as shown in FIG. 6, to produce unsealed side gas
discharge outlets positioned like the outlets 23 of the form of the
invention of FIGS. 1 and 2. As soon as the high spots of the cams
364 leave the followers 363, the pull-up springs 369 urge the upper
shoes 360 downwardly and, because of the geared arrangement, the
lower shoes 360 are moved upwardly. Preferably the shoes 360 are so
located as to provide side unsealed gas outlets near the trailing
end of the product 311 in each package, just as has heretofore been
illustrated and described at 23 in connection with the form of the
invention of FIGS. 1 and 2. This allows the gas to be forced along
the product 311 to act on all portions thereof before it leaves the
side gas outlets. The pressure wheels 318 apply the sealing
pressure after the material has been heated by the shoe heaters,
but there will be no sealing on those portions of the web which had
been unheated due to the skip-sealing action of the shoes 360, as
shown in FIG. 6.
After the web material leaves the pressure wheels 318 it is acted
upon by soft rollers such as the soft rollers 24 of FIGS. 1 and 2
and by all of the other instrumentalities illustrated and
heretofore described in connection with FIGS. 1 and 2, including
the use of wheels like the wheels 31 of FIGS. 1 and 2 having the
short heated sealing portions, like the portions 32 of FIGS. 1 and
2, positioned to engage opposite sides of the packaging material at
the unsealed gas discharge openings, such as the openings 23 of
FIGS. 1 and 2, to seal said openings.
In the modification of FIGS. 7-10, inclusive, all parts
corresponding to parts of the form of the invention of FIG. 1 are
designated by the same reference numerals which are, however, in a
400 series, and will not be again described. Here the sealing
wheels 418 each have a periphery with a skip-seal pattern formed by
transverse obliquely extending cuts or grooves 421, as shown more
clearly in FIGS. 8 and 10, the grooves of the upper wheels
registering with the grooves of the lower wheels when in the
position of FIG. 10. One or both of these wheels is suitably heated
in any well-known manner to perform heat sealing, but wherever the
transverse grooves 421 meet, as shown in FIG. 10, there will be
skip-sealing to produce a plurality of gas discharge outlets 423 on
each side of the package, as shown in FIGS. 8 and 9, which, of
course, will be regularly spaced throughout the length of the
package. After leaving the wheels 418 with the skip-seal pattern,
the packages are acted upon in the same way as heretofore described
in connection with the form of the invention of FIGS. 1 and 2,
except that, in lieu of the final side sealing wheels 31 of FIGS. 1
and 2, there are wheels 431 which are suitably heated to provide a
continuous seal for the purpose of closing the gas discharge
openings 423.
The present invention makes it particularly easy to treat
perishable products with a gas while the products are being
packaged with one or more longitudinal seals. While the preferred
embodiments of the invention discloses upper and lower web portions
12 which are originally separate and which must be sealed on both
sides, it is obvious that the invention is applicable to similar
packages formed from web material where the upper and lower web
portions 112 are integral and folded into superimposed position
along one side of the package as at 40 in FIG. 3, this type of
package requiring only one side seal produced by skip-sealing
wheels 117 having cut-outs 121. In this embodiment the gas
discharge openings would be along one side of the package only and
only one set of side sealing wheels, such as the wheels 30 of FIG.
1, would be required. While an important use of the present
invention is in the packaging of perishable products such as food
products, the invention also has important utility in connection
with the packaging of disposable items or devices which must be
maintained in sterile condition in the packages and prior to use.
Examples of such items are surgical pads and sponges and other
disposable items used by physicians and surgeons. When such items
are being packaged, the gas which is injected by the tubes 15 is a
suitable sterilizing gas such as ethylene oxide.
It is to be understood that I do not desire to be limited to the
exact details of construction shown and described, for obvious
modifications will occur to a person skilled in the art.
* * * * *