US3508373A - Method and apparatus for evacuating and gas-flushing packages - Google Patents

Description

April 8, 1970 ca. F. ROBINSON, JR 3,508,373

METHOD AND APPARATUS FOR EVACUATING AND GAS-FLUSHING PACKAGES Filed Sept. 20, 1967 6 Sheets-Sheet 1 3 Z Z? 25' 2 I 4 7% A l V/AZ/ZL I 35 7Z4Z4/ INVENTOR QK/VFZ M k ATTORNEYS April-28, 1970 G. P. ROBINSON, JR 3,508,373

METHOD AND APPARATUS FOR EVACUATING AND GAS-FLUSHING PACKAGES Filed Sept. 20, 1967 6 Sheets-Sheet 2 34 33 27 G H i I Q Z 1 J o @A F /0 L a INVENTORS \Z9. 2 f f/v FEw/NSM J12.

: ATToRfig April 1970 G. P. ROBINSON, JR 3,508,373

METHOD AND APPARATUS FOR EVACUATING AND GAS-FLUSHING PACKAGES Filed Sept. 20, 1967 A 6 Sheets-Sheet 4 ATTORNEYS April 1970 G. P. ROBINSON, JR 3,508,373

METHOD AND APPARATUS FOR EVACUAT-ING AND GAS-FLUSHING PACKAGES Filed Sept. 20, 1967 6 Sheets-Sheet 5 INVENTOR fizz/v Ffiaawsaag J.

ATTORNEYRS April 28,1970 G. P. ROBINSON, JR 3,508,373

METHOD AND APPARATUS FOR'EVACUATING AND GAS-FLUSHING PACKAGES Filed Sept. 20, 1967 v 6Sheets-Sheet e United States Patent 3,508,373 METHOD AND APPARATUS FOR EVACUATING AND GAS-FLUSHING PACKAGES Glen P. Robinson, Jr., Atlanta, Ga., assignor to Scientific- Atlanta, Inc., Atlanta, Ga., a corporation of Georgia Filed Sept. 20, 1967, Ser. No. 669,210

Int. Cl. B65b 31/04 U.S. Cl. 53-12 9 Claims ABSTRACT OF THE DISCLOSURE A method of evacuting air from a package and replacing it with another gas in such way that the residual oxygen content is less than achieved during evacuation. A package is evacuated and simultaneously air is removed from a reservoir which communicates with an opening at one side of the package. After evacuation ceases, said other gas is introduced into the package at a point remote from the opening so that the reservoir applies suction through said opening and the other gas sweeps through the package, through the opening and into the reservoir, carrying residual air with it.

The present invention pertains to a method and apparatus for filling a package with a gas other than air and more particularly to an improvement in which air in the package is substantially wholly removed from the package.

In the application of Allen et al., Ser. No. 499,896, filed Oct. 21, 1965, there is described an apparatus for flushing air from a package containing a perishable commodity, and replacing it with a gas other than air, for example nitrogen or carbon dioxide. A gas flushing method useful in that apparatus is disclosed in Harmon Miller application, Ser. No. 516,295, filed Dec. 27, 1965. that apparatus has been successful commercially for packaging weiners, sliced luncheon meat and similar commodities However, the efficiency of this process is relatively low since the residual oxygen depends upon the length of time and quantity of gases introduced into the chamber and package In actual practice, the volume of gas flushed through the package is approximately equal to three times the volume of residual air in the package. Theoretically, this should reduce the residual oxygen in the package from the original 21% present in air to approximately 2 /z%. In actual practice, the product in the package restricts the air flow and consequential mixing of the gas with the residual air, leaving the residual oxygen level more nearly at 5%. Obviously, an additional flow of gas for a longer period of time or at a higher flow rate will reduce the residual oxygen further, but this adds to the expense of the process and decreases the speed of packaging Therefore, while this process has proved satisfactory for packages stored under refrigeration for reasonably long times, it is desirable to extend shelf life as much as possible by removing more of the air.

A true vacuum packaging process is most commonly used to insure low levels of residual oxygen; however, vacuum packaging has certain disadvantages The package must either be rigid, such as a metal can or a glass jar, to prevent the container from collapsing under vacuum; or, the product must be rigid and the packaging material must be flexible, such as a thin plastic film, so that the film will collapse around the product under the influence 3,508,373 Patented Apr. 28, 1970 of the vacuum from within. In a gas package, it is possible to use a semirigid plastic package which is easy to handle and fill and provides a conveniently reusable receptacle for the produce after it is opened and part of the contents have been removed.

The present invention provides an improved apparatus in which a rather high vacuum is applied to the package and after air has been removed, the package is filled with another gas. The apparatus is so constructed that the amount of air in the package is reduced during the initial evacuation and is further reduced during the gas flushing.

In the gas flushing procedure described in the aforesaid Allen et al. application, the degree of vacuum can only be very low because gas is introduced at one side of the package while air is Withdrawn from the other side. The vacuum pumping equipment used cannot be selected for relatively high vacuum because it would be overwhelmed by the replacement gas, because of gasket leakage and also because a fair amount of that gas would be wasted.

It is known that this difliculty can be avoided by pumping air out of the package before the replacement gas is introduced, and disconnecting the vacuum pump from the package before the replacement gas can flow to it. However, in this case, the removal of air is limited by th capacity of the vacuum pump. An absolute vacuum is about 30 inches of mercury, but the pumping rate of a vacuum pump reduces as the vacuum increases A higher vacuum than 25 inches rarely can be produced in a reasonable time even with reasonably high volume pumping systems. In fact, it takes nearly twice as long to pump to 29 inches as to 25 inches, and this is too long for high speed packaging.

It can be computed that, when a package is simply evacuated and then refilled with another gas, with a 25 inch vacuum, and using absolutely pure replacement gas, the residual oxygen will be about 3.5% by volume. However, it is desirable to achieve a lower level in order to extend shelf life.

In accordance with the present invention, it is possible to achieve a residual oxygen content of only about 0.5% or less, even though the vacuum applied to the package is only 25 inches. Briefly, this is accomplished by simultaneously evacuating the package and a reservoir which adjoins it, disconnecting the vacuum pump, e.g. by closing a valve, and flowing the replacement gas through the package into the reservoir As the gas sweeps through the package into the reservoir it pushes and mixes with some of the residual air and transfers it to the reservoir.

The invention will be better understood from the following detailed description of a preferred embodiment, reference being made to the drawings, in which:

FIGURE 1 is a perspective view of the apparatus;

FIGURE 2 is a side elevation, partially in section, of the apparatus of FIGURE 1, with some parts removed for simplicity;

FIGURE 3 is a rear elevation of the lower portion of the apparatus;

FIGURE 4 is an elevation, partly in section, of the lower portion of the other side of the apparatus;

FIGURE 5 is a section of the portion of the apparatus in which gas flushing takes place, along lines 55 of FIGURE 1 some parts being omitted for clarity;

FIGURE 6 is a section of the same portion of the apparatus, along lines 66 of FIGURE 1, some parts being omitted for clarity; and

FIGURE 7 is a plan view of a package-supporting mandrel for use in the apparatus For convenience of description, the apparatus may be considered to be subdivided into a rotating table 1 which carries the packages, a flushing chamber 2, a label dispenser 3, a package closing chamber 4, a heat sealing press 5, and the drive mechanisms indicated generally at 6 which are beneath the rotating table 1.

The table 1 is a closed end hollow cylinder mounted for rotation about a vertical axis. There are six openings 7 in the top of the table to receive packages and there is a basket 8 under each of the openings to provide an air-tight cavity around the packages. There is an opening 9 in the bottom of each basket and a piston 10 is slidably mounted therein for vertical movement. The top 11 of the piston is relatively wide and ejects a package when the piston is raised by a cam under the table. It also prevents downward movement of the package during gas flushing, as will be explained below. The piston slides in a bushing 109 in the opening 9 which provides a gas and vacuum-tight seal.

At the edge of each opening 7, there is a recessed ledge 12, which receives a mandrel 13. The mandrel has a central opening 14, the edge of which is recessed to 'provide a ledge 15, the shape of which is shown best in FIGURE 7. The dimensions of the ledge are slightly larger than those of the cup which is to be inserted in it. Several mandrels may be supplied with the apparatus, having central openings which accept various sizes and shapes of packages, thereby permitting easy conversion from one packaging operation to another.

At the opposed ends of the mandrel, the ledge 15 is enlarged by recessing its side wall 150 to provide deflection areas 151 and 152. As will be explained further, the replacement gas is directed into one of these (151) and the vacuum line is adjacent the other (152). In addition, there are holes 153 drilled down through the mandrel in the deflection area 152 to communicate between the space in the cavity above the package and the space below the package which functions as the above-mentioned reservoir, as hereinafter described.

The gas flushing chamber 2 comprises a cover plate 16 preferably constructed of transparent plastic, permitting observation of the flushing step. A gasket 17 is provided under the sides which makes a gas-tight seal with the top of the rotating table 1.

At the radially inner and outer ends of the cover plate 16 there are threaded openings in which are inserted tubing connectors 18 and 19. These are attached to tubes 20 and 21 which lead respectively to vacuum and gas sources.

The label dispenser 3 is at one side of the rotating table 1 and includes a hopper 22 mounted directly over the path of the packages. The hopper is slightly more narrow than the labels so that they are maintained in a slightly bowed condition. Interchangeable hoppers may be supplied with the apparatus to permit easy adaptation to several sizes of packages.

Labels are dispensed by a moving arm 23 which extends radially inwardly over the table. The arm 23- carries two rubber suction cups 24 and 24 and means are provided for alternately supplying vacuum and air under pressure through a tube in the arm to openings within the suction cups. In operation, the arm is raised with the suction cups turned upwardly, until they touch the bottom of the labels in the hopper 22. Suction is applied and the arm is lowered, Withdrawing the bottom label. The arm is rotated 180 as it moves downwardly to invert the label, and places the label on a package in a mandrel 13 at the bottom of its stroke. At that point, the arm actuates a microswitch (not shown) which operates a valve disconnecting the suction and introducing air under pressure to the suction cups. This causes the label to drop quickly onto a package.

The package closing chamber 4 is spaced 60 from the gas flushing chamber and comprises sides 25 and a top 26 suspended from a crank housing 27 and resting on the rotating table 1. A gasket 28 is under the sides to provide a relatively gas-tight seal to the rotating table 1. The radially inward side is removable, being held in place by quick detach devices, permitting access to a heat sealing mechanism for interchanging of heating platens.

Between the gas flushing chamber 2 and the package closing chamber 4 there is a low chamber 4'. This is a casting having a top and sides, the sides resting on a gasket, which makes a relatively gas-tight seal with the table. The chamber 4 is attached at one end to the package closing chamber 4. It prevents unnecessary escape of the gas as the package is moved from the gas flushing chamber to the package closing chamber.

The package is closed by the heat-sealing press 5 which includes an electrical heater 29 and an easily interchangeable heating platen 30 depending from and in contact with the heater. The plate includes a downwardly extending member having the shape of the outer edges of the package to apply heat and pressure to the edge portion only of the lid, thereby heat-sealing the lid to the package without excessive heating of its contents. The electrical heater is at the bottom of a plunger 31 which is mounted for vertical sliding movement in a compartment 32 at the inner end of the crank housing 27. The plunger carries a laterally-extending pin 33 on which is mounted a ball bearing which engages in a slot in the inner end of the bell crank 34, the bell crank being pivotally mounted in the outer end of the crank housing. Vertical movement of the plunger is accomplished by inward and outward movement of the lower extremity of the bell crank, by means to be described further herein.

As a package leaves the package closing chamber 4, it indexes to the next station where it is raised by the piston 10 and ejected. A piston is maintained elevated at the ejection station and then an arm 35 sweeps across, propelling the package outwardly onto a downwardly inclined conveyor 36. The piston is lowered as the table indexes to its next position.

The drive mechanisms are in a housing beneath the table 1. All power for the above-described mechanical movements is provided by an electric motor 37. A clutchbrake mechanism 38 is connected to the shaft of the motor which alternately supplies motion to and brakes the moving parts. That is, when motion is to be supplied, the clutch, which is connected to the motor shaft, is engaged, and the brake, which is connected to an output drive shaft 39, seen in FIGURE 2, is disengaged. To stop motion, the clutch is disengaged, and substantially simultaneously, the brake is engaged.

A pulley 40 is mounted on the output drive shaft 39, connected by a belt to another pulley 41 on an input shaft 42 of a reduction gear set 43. The output of the reduction gear set is an upwardlyextending vertical shaft 44 on which are mounted a sprocket wheel 45 and a cam 46.

The cam 46 operates the bell crank 34, by means of a horizontal crank arm 47 to reciprocate the heating platen 30. One end of the crank arm is pivotally mounted on the housing of the drive mechanism 6, and the other end is pivotally mounted on a link 48 which in turn is pivotally connected to the bottom of the bell crank 34. At the center of the crank arm, there is a depending bearing 49 which engages the cam 46, and, to hold the bearing against the cam, there is a tension spring attached, at one end, to the link 48 and, at the other end,

to the housing. The construction of the cam is such that spring tension holds the heater elevated during rotation of the table and onto a package while the table is stationary.

The sprocket wheel 45 is connected via a chain 50 and a sprocket wheel 51 to the input shaft of a Geneva drive mechanism 52. The intermittent output of the Geneva drive is through a vertical shaft 53 on which the table is mounted.

The package ejector mechanism comprises a vertically reciprocating rod 54 pivotally connected at its bottom to one end of a cam actuated crank cam 55, the middle of which is pivotally mounted on the housing. There is a cam 56 on the input shaft of the Geneva drive which engages a bearing 57 on the crank arm 55. The cam raises and lowers the rod 54 which is normally held down by a spring 58, the bearing 57 consequently being urged upwardly against cam 56. During approximately 270 degrees of rotation of the input shaft of the Geneva drive and cam 56 while table 1 is stationary, cam 56 elevates rod 54 and therefore piston 10. This construction causes the package to be elevated for removal by the arm 35.

The sweep arm 35 is secured at the top of a vertical shaft 60 mounted for rotation in a bearing in the housing. At the lower end of the shaft 60, there is attached one end of a crank 61. The other end of the crank carries a pin 62 and also is connected to a tension spring 63. The other end of the tension spring is attached to the housing and it pulls the crank 61 to turn the shaft 60 and hence the sweep arm 35 to its retracted position.

There is a sprocket wheel 64, mounted to engage the chain 50, to which there is pivotally attached one end of a crank arm 65. At the other end of the crank arm 65, there is an elongated slot which receives the pin 62. As the sprocket wheel 64 turns, the crank arm 65. moves the crank 61 against the tension of spring 63 and then provides lost motion as the sprocket wheel continues to turn. Consequently, the arm 35 sweeps a package from the table, retracts, and then remains stationary as the cycle of operation continues.

Electrical control of the moving parts of the apparatus is achieved by a microswitch actuated relay which op erates the clutch-brake 38. Various means may be provided for regulating operation of the clutch-brake, for example the system described in the aforesaid Allen et al. application. However, a fail-safe system, described below, is preferred.

An important feature of the present invention is the opening into the mandrel 13, which is only slightly wider than the cup to assure proper alignment with the lid dispenser and heating platen. The ledge 15 also is recessed below the top of the table to provide space above the cup into which the lid is :bowed. As a result, a tunnel is formed over the cup by the lid, but the bowed lid can still pass under the gasket which seals the chamber 4 to the rotating table 1. Also, gas flows through this tunnel and around the contents of the package during evacuation and flushing. A lid of aluminum foil or aluminum foil laminated to paper, which is preferred for its high efliciency as a gas barrier, is especially useful because, once bowed, it will retain this configuration. It also is possible to use a cardboard lid if treated to be gas-tight, or a plastic lid which is scored to fold into a bowed shape. The bowed lid provides a further advantage in that, when the package is closed, the lid remains slightly elevated at its center for an attractive appearance.

As seen in FIGURES and 6, flushing is accomplished when a package is positioned below the plate 16. This plate is elevated above the table 1, preferably about 4; inch, by a crank 70 (see FIGURE 1) when the table is indexed, and lowered against the table when it is stationary, the gasket 17 sealing against the table an enclosed volume which constitutes the flushing chamber 2. A pneumatically-controlled elevating system including a vacuum operated piston also has been used.

The receptacles which are used preferably comprise a bottom 71, a side wall 72 and a flange 73 extending laterally outwardly from the side wall. Preferably, there is a resilient gasket 74, e.g. neoprene rubber, at the inner edge of the ledge 15, so that the flange 73 seals against the ledge, preventing gas flow between them. This assures that gas communication between the volumes above and below the package will be directed through the holes 153.

In operation, the receptable is placed in a mandrel, a lid is placed on it and the mandrel is indexed into position below the plate 16. Then the plate is lowered. The subsequent steps involve evacuation and refilling. For this purpose, there are valves 75 and 76, indicated schematically in FIGURE 5, in the tubes 20 and 21 and controlled electrically by means not shown, e.g. solenoids. The valve 75 is opened and the chamber communicates with a suitable vacuum source. Air is withdrawn from the package, from the volume above the package and the mandrel and, through holes 153, from the volume below the mandrel, i.e., the hereinbefore-mentioned reservoir. Typically, this requires one-half second, although the exact time will vary with the size and shape of the package and the shape and kind of contents. It will be appreciated that simultaneous evacuation of the spaces above and below the mandrel prevents package collapse at this time. Then valve 75 is closed and valve 76 is opened. This permits gas to flow from a source of it under pressure, e.g. a tank of carbon dioxide. The gas first flows into the package and through the tunnel-like passageway defined by the lid 77 bowed upwardly over the flange 73. A smaller portion also flows around the the lid above the ledge 15. As the gas proceeds through the package, it forces unevacuated air ahead of it, mixing in part with it, and exits through the other end of the tunnel-like passageway. Then it and the gas are drawn through the holes 153 into the volume below the ledge 15. Generally, this flushing time takes about V second although this will vary with the factors mentioned above.

When the gas first enters the package, there will be an instantaneous pressure differential of several p.s.i. between the volumes above and below the mandrel. This might tend to push the package through the opening in the mandrel by bending the flange 73. However, the platform 11 on the piston 10 can be thick enough to lie against the bottom of the package and prevent its downward movement. Also, friction between the flange 73 and the gasket 74 reduces tendency for slippage of the flange.

In one embodiment, the piston 10 is maintained partly elevated after a package is ejected, so that it is approximately flush with the bottom of a receptacle. This may be accomplished through a track under the paths of the pistons. These tracks may be interchangeable to permit handling various package thicknesses. Elevation of the piston also is useful for use with automatic package insertion equipment which slides a package across the opening 14.

In a preferred mode of operation, controls are used to assure that the lid placement, evacuation and gas filling operations only take place when a package has been placed in a mandrel, gas filling is delayed until a preselected vacuum is achieved in each package and a gas filled package is not moved to the sealing station until the gas pressure reaches a preselected level. The system for achieving these effects has not been illustrated in the drawings because conventional components have been used, but it will be described briefly.

Initially, the machine is turned on, i.e., the motor 37 is turned on. This causes periodic indexing of the table, and other operations. Packages are fed into vacant mandrels either manually or by means of an automatic infeed machine. Preferably, the presence of a package in a mandrel is detected. This may be accomplished by passing a beam of light through the mandrel and detecting the beam witha photocell. For example, a mirror 500 mounted on the radially outer wall of a basket 8 will reflect light toward a photocell mounted on the package closing chamber 4. The photocell can be connected to a circuit which responds only to a preselected minimum signal to avoid the .effects of ambient light. The output of the package detector is coupled to the lid dispenser to prevent suction being supplied to suction cups 24 and 24' after the table indexes, so that no lid is dispensed when there is no package in a mandrel. Lowering of plate 16 is coupled to lid dispensing, so that, when no lid is dispensed, the plate remains elevated for the next cycle. The vacuum control valve for evacuating a package is relay controlled by the lowering of plate 16, so that there will be no evacuation unless there is a package in a mandrel or until plate 16 is down.

Once valve 75 is opened to start evacuation, its operation may be controlled by a manometer which also regulates valve 76. For example, a two-way diaphragm controlled switch can be coupled to line 20 so that valve 75 remains open until the pressure is reduced, say, to 25 inches. Then, the preset diaphragm will operate the switch to close valve 75 and open valve 76. Gas flows into the package until the diaphragm again operates the switch upon reaching a preselected positive pressure. Through suitable relays, lifting plate 16 is delayed until that time, and indexing of the table is delayed until plate 16 is lifted, to assure that every package is properly evacuated and refilled, providing automatic quality control.

Substantially any gas may be used as the replacement gas. For ordinary purposes, an inert gas such as nitrogen may be satisfactory. However, it also is possible to use a preservative gas such as carbon dioxide which actually retards spoilage of luncheon meats and cheese, or nitrogen oxides which have been proposed for the same purpose. It has been proposed to use a pure oxygen environment for packaging fresh meat, and the present process is suitable for that purpose. Also, it has been suggested to package fresh meat in a carbon monoxide environment to give it a fresh appearance. While the practicality of that atmosphere is not known, the present process would provide a satisfactory way of introducing that gas into a package.

It will be seen that the present process utilizes a package of the same type described in the aforesaid applications, and that the lid is bowed upwardly over the package as also described therein. However, the improved vacuum-fiushing method provides significantly more effective replacement of air.

The process and apparatus have been described in connection with a preferred embodiment. However, various changes may be made in details of construction and mode of operation without departing from the invention, the scope of which is defined in the appended claims.

I claim:

1. A method of replacing air in a package with another gas, said method comprising evacuating air from a chamber in communication with the interior of said package and simultaneously evacuating air from a substantially closed volume reservoir having an opening for evacuation and filling of gases, which communicates between said reservoir and said chamber, interrupting evacuation of said package and said reservoir after the air pressures in said chamber, said package and said reservoir have been reduced, introducing said other gas into said chamber, said opening of said reservoir communicating with said chamber at a point remote from the point where said other gas enters said package, so that said other gas mixes with residual air in said package and said chamber and sweeps it toward and into said reservoir through said opening, further reducing residual air content of the package.

2. A method of replacing air in a package with another gas,. said method comprising evacuating air from said package and from a substantially closed volume reservoir having an opening for evacuation and filling of gases adjacent to one side of said package, said package having an opening adjacent said opening of said reservoir, interrupting evacuation of said package and said reservoir after the air pressures in said package and said reservoir have been reduced, introducing said other gas into said package from a source adjacent a point remote from said opening in said package, said other gas flowing into said package at said remote point and mixing with residual air in said package while said reservoir applies suction through said opening in said reservoir and the adjacent opening in said package and said other gas and residual air flowing through said package and toward and through said opening in said package and into said reservoir through its opening, further reducing residual air content of the package.

3. A method as set forth in claim 2 in which said package comprises a cup having a bottom, upwardly extending sidewalls and a flange extending laterally outwardly from said sidewall, and a lid resting on said flange and bowed outwardly from said cup to define a tunnellike passageway between the cup and lid, said other gas being introduced into one end of said tunnel and said opening into the package being the other end of said tunnel.

4. Apparatus for replacing air in a package with another gas comprising a gas flushing chamber,

means communicating between a first point in said gas flushing chamber and a source of said other gas under pressure,

means communicating between a source of vacuum and said gas flushing chamber,

means substantially enclosing a substantially closed volume reservoir having an opening communicating with a second point in said gas flushing chamber for withdrawing air from and filling said other gas into said reservoir, said reservoir and said source of other gas communicating with spaced points in said gas flushing chamber,

and means for independently interrupting communication between said gas fiushing chamber and said vacuum and other gas sources,

whereby said reservoir and a package in said gas flushing chamber may be evacuated simultaneously and, after interrupting evacuation, said other gas may enter said chamber and said package, and mix with residual air in said package, sweeping it into said reservoir.

5. Apparatus for replacing air in a package with another gas comprising:

a table,

an open topped walled cavity in said table,

a ledge around said Walled cavity below the top of said table to support said package, said ledge having at least one opening therethrongh for exchange of gases between the portions of said cavity above and below said package, said ledge with said package separating said cavity into said upper and lower portions communicating substantially only through said opening,

a cover for said cavity, means for elevating said cover above said table and lowering said cover onto said table, said cover forming a gas-tight seal with said table,

means for evacuating said cavity,

and means for introducing gas into said cavity above said ledge at a point remote from said opening to flow through a package resting on said ledge and into the portion of said cavity below said ledge.

'6. Apparatus as set forth in claim 5 in which said table has a plurality of said cavities and including means for moving said table to successively position said cavi- 5 ties below said cover for gas flushing.

7. Apparatus for replacing air in a package with another gas comprising:

a chamber,

divider means in said chamber, said divider means supporting a package and having at least one opening therethrough for exchange of gases between said compartments, said divider means with said package separating said chamber into two compartments,

means for evacuating said chamber,

9 10 and means for introducing said other gas into one of package seating against said ledge to prevent gas exsaid compartments at a space remote from said ge C P through Sai Op ning. opening, to flow through a package and through said opening to said other compartment. References Clted 8. Apparatus as set forth in claim 7 in which said 5 UNITED STATES PATENTS opening is substantially the only gas passageway between 2,442,161 5 /1948 Bergstein 53x22 said compartments 3,139,505 6/1965 Sloan et a1. 52 22 X 9. Apparatus as set forth in claim 7 in which said divider means is a ledge projecting from the walls of TRAVIS MCGEHEE Pnmary Exammer said chamber and there is a hole within said ledge to 10 US. Cl. X.R. receive a portion of said package, other portions of said 5322, 86, 112

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