US2296828A - Method of canning - Google Patents

Description

Sept. 29, 1942. c':. 0. BALL METHOD OF- CANNING' Filed mm}. is, 1939 2 Sheets-Sheet 1 4 4.4 MLQ.

ATTO NEYS INVENTOR. a.

Sept. 29, 1942. 0. BALL METHOD OF CANNING Filed Nov. 18, 1939 2 Sheets-Sheet 2 III/III a w\.. n

IIA rill/Ill!!! /////1/// V WA ORNEYJ Patented Sept. 29, 1942 UNITED. STATES PATENT: OFFICE I 2,!9628 V METHOD or cAnNmG' Charles 0. Ball, Mount Vernon, N. Y., assignmto American Can Company, New York. N. Y., a corporation of New Jersey Application November 1:, 1939, Serial No. 305,191 5 claims. (CL 99-182) The present invention relates in general to an respects the invention is an improvement upon; my Patent 2,029,303, issued by the United States Patent Oflice on February 4, 1936. e

In my former patent which treats of sterilizing a product, sterilizing a can and also a cover and introducing the treated product into the can and sealing the product in the can, provision is made for handling the sterilized product and can parts in an enclosed chamber or chambers the interiors of which are maintained under a pressure greater than the atmospheric pressure outside of the chambers so that contamination of the interior walls of the chamber as well as contamination of can or product passing therethrough will be prevented even though there may exist leaks in the apparatus.

v In some cases, as in my Patent No. 2,209,315 issued by the United States Patent Ofllce on July 30, 1940, provision is made for handling the sterilized product and can parts in an enclosed chamber or chambers the interiors of which are main-- tained under a pressure less than the atmospheric pressure outside of the chambers and these chambets are protected by outer surrounding jackets Any inward exchange of pressure would be that of the sterile atmosphere and therefore will not have any contaminating results on .the inner chamber walls or the cans and covers and prodwhich are maintained at a-pressure less than any pressure existing within the inner chambers so that any leaks in the inner chamber walls or the jacket walls will be toward the interior of the jackets and thereby prevent contamination; of

the interior walls of the chambers as well as contamination of can or product passing therethrough.

In the present invention provision is made for utilizing an interior treating chamber pressure less than normal or outside-atmospheric pressure and insuring at all times an additional controlled and sterile surrounding atmosphere just exterior .to the chamber. This controlled and sterile-atmosphere is maintained at a pressure slightly greater than the outside atmosphere. With this condition prevailing at all times-should there be leaks in the apparatus, bacterior or other types of contamination could'not enter the treatin chamber as any outward exchange of pressure would'be between the outer protecting jackets andv the outside atmosphere and therefore the nets therein.

An object of the present invention is the provision of a method of treating a product under sterile conditions by introducing it into an inner sealed 0 ber wherein there is maintained a chamber atmosphere of desired absolute pressure, there also being provided a surrounding confined and controlled sterile atmosphere of greater pressure than normal atmospheric pressure so that possible contamination of the product while within the inner chamber is entirely eliminated.

A further object is the provision of a method T of treating a sterile product which includes control of a created sterile atmosphere in protecting? jackets exterior to a treating chamber so that if,

leaks in the protecting jackets outer there are any walls no contamination from the outside will enter through the leaks because the-sterile atmos- "phere w-ill' pass through the leaks outwardly and thereby keep out the outside atmosphere.

Still another object is the provision of a method of evaporating a liquid within a vacuum chamber, the chamber being protected against contamination by'a surroundingand confined sterile atmosphere which is atall times:held under a I pressure greater than that obtaining outside of the apparatus. f

Numerous otheriobjects and advantages of the invention will be apparent as'it is better understood from the following description, which, taken in connection with the accompanyingv drawings,

discloses a preferred embodiment thereof.

Referring to the drawings:

Figure 1 is a schematic view illustrating a series I of interconnected mechanisms for performing various steps in the treatment of a product which in one case is of liquiform nature or as inanother caseof the discrete particle type and illustrating the manner of protecting the treating chambers by surrounding Jackets confining a space which under sterile conditions .and with is maintained a pressure greater than the outside atmospheric p e e:

Fig.2 is an enlarged sectional view taken substantially along the line 2-2 in Fig. 1' parts being broken away;

F g. 3 is a fanciful sectionabview taken substantially along the line 3-3 in .1 and illustrating" the means of protecting one of the valve outside normal atmosphere will not be involved.

openings associated with the can sterilizer; and Fig.4! is a transverse sectional view of the are shown as seamed covers.

these are designated discharge valve of the apparatus illustrating the protection of the valve surfaces against contamination, this view being taken substantially along the line 4-4 in Fig. 1;

The invention contemplates the passage of a food product or the like through a treating chamber, the drawings illustrating an initial step of sterilization and showing alternate treatments for a product of a liquiform nature and one consisting of discrete particles. When the (sterilization of a discrete particle product is taking place some of the mechanism which applies only to liquiform products is closed off from operation and in like manner. other mechanism the empty cans as well as the covers. The present invention is directed specifically to conditions applying to a treating chamber and therefore it is only incidental whether a can is used during the treatment. If the product is not to be put into a can obviously the treating chamberwill be slightly changed to meet whatever conditions obtain.

The connecting passageways between the various chambers or sections of the same chamber provide for a sealed space for treatment of product as desired and provision is made for enclosing the walls of the chamber or chambers with a surrounding jacket. The space within this jacket may be connected with a source of sterile gas, such as sterile air, other non-condensing gases, or pure steam, this gas beins maintained under a pressure approximately one pound in excess of the atmosphere outside of p the apparatus.

The enclosing Jacket, as will be hereinafter more definitely shown in detail, is coextensive with any outside wall part of the treating chamber so that entrance of contamination from the outside will be prevented. By maintaining an absolute pressure in the surrounding Jacket which is greater than the outside atmospheric air pressure, any leakage of gases, vapors, etc., through wall 33, where it is protected by a suitable stufling box, and into the, wall 32.

ilizing apparatus 22 and enters a cooling device 24. This device 24 discharges a sterilized and cooled product through a passageway 25 which extends from one side of the cooling device. A manually o erated gate valve 26 is introduced 'inthe passageway 25 and is' used to seal oi! the passageway when this part of the apparatus is not being used. The passageway 25 leads to .a filling chamber 21 where it is introduced into cans preparatory to entering the treating chamber.

The cooling device 24 is surrounded by an outer spaced wall 23 which also extends around the passageway 25 and furthermore encloses the gate valve 25. This spaced wall'encloses at protecting jacket 23 and provides an enclosurefor the entire cooling operation as well as the passageway 25'. Only the operating hand wheel of the gate valve 28 extends outside of the Jacket wall 28 and provision is made for packing this joint so that there will never be any means'of entrance of contamination into the cooling chamber or into the passageway 25. r

The hopper section and the sterilizing device may be provided with live steam and steam pipes v3|) are provided for this purpose. The protecting chamber 29 surrounding the cooling device 24, the gate valve 25 and the passageway 25 are adapted to be maintained under a desired pressure which at all times is greater in absolute pressure than that of the outside atmospheric air. Pipes 3| leading to a. suitable source of sterile air, other noncondensible gas, or pure steam under pressure may be used for this purpose.

The filling chamber 21 is contained within an irmer housing '32, and an outer spaced wall 33 surrounds the chamber in all directions so that a protecting space 34 is provided between the walls 32, 33 and this constitutes a protecting Jacket or chamber which is also adapted to be held under gas pressure so that the absolute pressurewithin the jacket will always be slightly greater than that existing in the outside atmospheric air. A pipe 35 extends through the outer This permits the entrance of steam into the filling chamber, or

the protective chamber walls and any le k g through entrance or exit openings will always be outwardly and at no time will there be any tendency for contamination of any kind to enter from the outside.

For the purpose of more clearly illustrating the various steps of the present invention reference should be had to Fig. 1 which represents schematically the principal parts of an apparatus for carrying out these steps. In the description which follows consideration will-first be given to the treatment of a product of the discrete particle type.

The product is or may be first introduced into a hopper 2| of a product sterilizing apparatus 22. In this consideration of a discrete product,

garden peas will be taken as an example and product passes from the hopper and through. the

sterilizing apparatus after which, if the sterilisection consists of a heat treatment, the starilized product moves downwardly from the starby the numeral 23. This the withdrawal of vapors from the chamber in order-to maintain the prescribed absolute pressure therein.

While the sterilized and cooled peas 23 are passing into the filling chamber open ended cans 35 are conveyed along a runway 3| and pass into one of a plurality of pockets 33 of a rotary valve 33 mounted on a vertical shaft 40. This valve member constitutes a movable element of a can sterilizing apparatus and is surrounded by a hollow casing or series of casings 4|. The first casing, that is, the one through which the runway 31 extends, preferably encloses a vacuumizing chamber 42 and connects with a suitablefsource with'its can passes along the chamber.

The casings "4| adjacent that which encloses the vacuum chamber 42 enclose steam chambers 44 receiving live steam preferably at high pressure through a pipe 4.5. The steam chambers 44 are preferably interconnected ;by means of a pipe 43. During the continued rotation ofthe valve 33 in the direction of the arrow the empty cans are successively subjected to the steam.

chambers 44 and upon completion of one rotation of the valve the cans carried thereby are sterilized.' The chambers 44 may be provided with a drain pipe 41.

The sterilized cans are thence transferred from the valve pockets of the sterilizer and pass through a passageway which connects with the filling chamber 21 of the filling apparatus. Each can upon reaching the filling chamber is engaged by a starwheel 52 which moves it through the filling chamber, putting it into fill-' ing position to receive'a charge of the product 23-. This filling of the can in the sterile filling chamber takes place under completely aseptic conditions the walls of the chamber completely enclosing the apparatus.

The spaced walls 33 which enclose the filling chamber are extended to the can sterilizer and adjacent the turret 39, these walls spread'ng out into a rotary turret seat casing 53. tecting chamber on the inside of the walls thus extends into this turret seat wall 53 and terminates in an annular opening 55 (see also Fig. 3). This opening preferably completely encircles the end of the passageway 5| which is adfacent the turret 35 and thus prevents the' entrance of any contamination from the outside The prointo the passageway or into the cans passing therethrough. In some cases, for example where it is desired to prevent the high pressure steam in the turret pockets 38 from entering the protecting chamber 35, suitable bridge members may be inserted in the openings 56 to block off traversed by the pocket section of the turret.

The filled and sterilized can with its sterilized product is thence transferred through a passageway 55 (Fig. 1) which opens at one end into the filling chamber 2?. At the opposite end the passageway communicates with a chamber 56 in which is located a starwheel 5?. The can passing from the passageway 55 is received by one arm of the starwheel 5'! and after being swept in a circular path of travel through the chamber 58 is introduced into a closing chamber 58.

The wall 32 which encloses the filling chamber 2i continues as the enclosing wall for the chambers 56 and 58. In like manner the spaced wall 33 extends in spaced relation to completely encircle the chamber 56 and also the chamber 58. The protecting jacket space thus merges into a protecting space 59 for the starwheel chamber 56 and the sealing chamber 53. This jacket space provides for protection against contamination of the chambers 56, 58 and will be'hereinafter again discussed.

Steam pipes 60 pass through the outer spaced wall 33 adjacent the starwheel and seaming chambers 56, 58 and provide for the introduction of steam into these chambers or for the with drawal of vapors from the chambers in order to maintain the prescribed absolute pressure therein. Where these pipes pass through the protecting jacket walls 33 provision is made for suitable stuffing boxes to prevent-any contamination from the outside along the surface of the pipes.

While the foregoing operations aretaking place can covers iii are advanced through a runway 62 and positioned successively into a plurality of pockets 63 of a valve member 64 mounted on a vertical shaft 65. This .valve constitutes a movable element in a can cover sterilizing apparatus. The valve 64 is continuously rotated that portion of the opening which is normally 1 the casing 65 of the can cover sterilizer.

annular opening l5 joins with the end of the this chamber.

62 extends there is provided a vacuum chamber 61 and a pipe 68 provides a means for evacuating As the cover 6| within the turret pocket 63 passes adjacent the chamber 61 air is removed from the pocket and from the surfaces of the cover.

Adjacent the :casing containing the vacuum chamber 6'! the casing sections 66 enclose steam chambers 69. Steam at a desired temperature may be circulated through the steam chambers 69 by means of pipes 10 the drawings illustrating two such chambers connected together by a suitable steam lpipe connection I0. j

By the time the turret 54 has made one complete rotation and the covers resting in the turret pockets have been subjected to the steam within the steam chambers 69 these covers are in a sterile condition. The sterilized covers are thence removed through a passageway II and positioned into a chamber enclosed in a cover cooling apparatus 12. The covers pass from the passageway H into a pocket of a starwheel 13 mounted on a vertical shaft 14. This starwheel carries the covers through the cooling chamber of the cooling apparatus.

The passageway H and the cooling chamber 12 are enclosed within suitable walls which may be a part of or connected with the chamber walls I 32. This wall as illustrated in the drawings where it encloses the passageway H extends into one of the casing sections 58 of the can cover sterilizing apparatus. Q

The spaced wall 33 also extends in spaced relation throughout the full extent of the inner wall 32 and encloses a protecting space 'which is an extension of the space 59. This protecting space or jacket completely encircles the cooling apparatus 72, the passageway H and extends into An jacket space '59 within-the casing section 6'5 (as best illustrated in Figs. 1 and 3) and this annular space 15 completely surrounds the entrance opening to the passageway H adjacent the face or" the turret 5 3. In some cases, as hereinbefore paratus l2 as'by means of pipes 16 which extend also through the wall 33 where they are suitably packed against contamination from the outside.

The step of cooling a can cover after sterilizing may in some cases be dispensed with but where a plastic sealing compound is used in the covers as a gasket for forming a hermetic seal between cover and can it may be desirable that the can cover be cooled prior to its introduction into the sealing chamber. It is the heat of the steam used in the sterilizer that is extracted in this manner.

The sterilized and cooled covers 5!, in passing from the cooling apparatus 12, travel through'a passageway 11 which is formed inside of the chamber walls 32 and which connects the cover cooling apparatus with the chamber 56. This permits introduction of the can covers into the starwheel 5'! which loosely places a cover upon each can fed into the chamber 58 through passageway 55. It will be understood that the starwheel 5'!- may be of double construction so that the lower section of the starwheel will provide for transfer of the can from the passageway 55 into the chamber 56 and the upper part of the starwheel will correspondingly handle the can cover.

The filled cans with their loosely applied covers upon leaving the starwheel chamber 56 pass into the can closing and sealing chamber 58. The numeral I8 designates a suitable closing machine, the seaming head or other part of this machine being fully enclosed within the sealing chamber 58. 'The protecting chamber 58 also extends around the closing chamber 58' and around the sealing mechanism I8 so that at no time will there be-any opportunity for contamination to enter into the sealing chamber. Suitable pipes 19 extending into the outer shell 33 of the protecting jacket 59 or its corresponding jacket 34 may provide for introducing the sterile gas into this protecting jacket.

The filled and sterilized can with its superimposed sterilized cover upon passing into the sealing mechanism I8 within the sealing chamber '58 is hermetically sealed. The hermetically sealed can is thence removed from the sealing chamber by a discharge valve 88 operating in an enclosing housing 8| which joins with the walls 32, 33. The valve 88 comprises a multiple pocket turret 82 mounted on a vertical shaft 83 (see also Fig. 4) the hermetically sealed can passing into one of the pockets and being conveyed by the valve into a discharge chamber.

It will be observed by reference to Figs. 1 and 4 that the discharge end of the sealing chamber 58, where it contacts the turret valve 82, is completely encircled with the protecting chamber 59 and the shaft 83 where it extends through the chamber walls is suitably provided with stufling boxes of other means of protection against contamination from the outside.

The casing wall 8| extends into an elongated housing 85 which encloses the discharge chamber designated by the numeral 86 through which the cans pass from the valve 82 onto a discharge plunger 81. The chamber 86 is filled with live steam or other sterile medium which constantly sweeps out the chamber by escaping through a suitable discharge opening formed in the housing 85. trance of air or other bacteria carrying medium into the discharge valve 82' and thus maintains a sterile condition in th apparatus. Means are provided to seal the elongated housing 85, except for a small steam vent, so that the interior of the. housing can be sterilized with steam under pressure before operation begins.

Steam when it is used as a protecting medium is introduced into the discharge chamber 88 through a steam pipe 88 and through pipes 89 leading into both sides of the housing 85. The

cans upon being brought successively to the plunger 81 are discharged by it from the chamber 86 in any suitable manner.

Consideration will now be given to the alternate phase of treatment of liquiform products and the sterilization and evaporation of milk will be given by way of example. The sterilized-and evaporated milk after this treatment will be brought into the filling chamber 21 and following its receipt the further treatment of the milk will parallel the handling of the garden peas as has already been fully described as exemplary of a The discharge chamber 86 thus prevents enproduct of th discrete particle type. Description of this latter or further treatment of milk will therefore not be repeated.

Preparatory to sterilizing and evaporating milk 5 in the apparatus the gate valve 26 (Fig. 1) will be fully closed and this shuts off from use the various mechanisms specifically relating to discrete particle products that have already been previously described.

As best illustrated in Fig. 2 the milk may be pumped through a terilizer 8! where the milk is sterilized as it is forced therethrough. The milk is first introduced into the apparatus through a pipe 82 which passes it into a liquid pump 83 which may be of the rotary type. This pump forces the milk through a pipe 94 and into the sterilizer.

A form of sterilizer suitable for sterilization of the milk. is herein shown as consisting of a series of circulating heating coils each coil comprising two concentric spaced pipe elements 85 located within a sealed housing 86 the milk being caused to traverse a sinuous path between each pair of concentric pipes. The pipe walls constitute in this instance heated surfaces. Header members are associated with the ends of the pipes 95 to insure proper transfer of the milk from one set of pipes to the other. The milk is finally delivered at the top of the housing 86 through a pipe 81.

During the passage of milk through the pipes it is heated to a high temperature receiving its heat through the walls of th concentric pipes. These wallsurfaces are preferably heated by steam which is introduced into the housing 96 and which circulates around the exterior of the outer pipe elements and also passes through the inside of the inner pip of each pair of pipes. A pipe 88 leading into the top of the housing may be used for introducing the steamat the proper pressure and temperature to effect the required transfer of heat to the milk.

Since the milk is in a thin film-like form by reason of the close space between the concentric pipes, i. e., the pipe surfaces between which the milk passes, it picks up or rapidly absorbs the heat. The housing 86 is also provided with a drain pipe 88 from which condensate may be withdrawn. A vent l8| may also be mounted in the housing preferably near the top for venting the space surrounding the heating coils.

The heated milk is thus fully sterilized and is then passed through the pipe 91 into a vacuum pan I85. A manually controlled valve I86 may be located in the line 91 to control the amount of milk passing through the discharge pipe 81.

If desired the milk in its passage through the pipe 81 can be cooled to approximately its. evaporation temperature before entering the vacuum pan.

The vacuum pan- I85 comprises a cylindrical housing I8'I which is fitted with a dome-shaped top section I88 and a cylindrical bowl-like bottom- I88. A baflie plate Ill may be secured to the inner wall of the-vacuum pan and is preferably curved to extend over the outlet of the pipe 81. The milk flowing through the pipe and entering the vacuum pan strikes against the bafile plate and is caused to discharge properly into the vacuum pan. It will be understood that the 70 milk entering the pan is subjected to the vacuum within and cooling andcondensation take place.

The evaporated milk which collects in the vacuum pan I85 is designated by the numeral 75 H2. Heat is applied continuously to the body of milk while in the pan to maintain the temperature of the milk at a point where efficient evaporation takes place. A heating coil I I3 is provided for this purpose which is submerged in the body of the milk on the inside of the vacuum pan, its terminal ends I I4, II5 extending outside of the pan. Steam at suitable temperature and pressure may be circulated through the heating coil and thus impart the required heat to the body of milk in the vacuum pan.

The dome top I08 of the vacuum pan is connected to a header pipe I2I which leads into a suitable condenser I22. Any suitable means of evacuating the condenser may be used as by a low vacuum pump I23 which connects with and operates through the condenser. By means of this pump a desired degree of vacuum may be maintained at all times in the condenser and by its connection with the vacuum pan the desired degree of vacuum will be maintained in the pan.

The evaporated milk is adapted to be withdrawn from the vacuum pan through a discharge pipe I25 which connects into a pump I26 by means of which the milk is forced into a filling pipe I21 (see also Fig. 1) which conveys the milk into thefilling chamber 21. A hand operated valve I28 is located in the pipe I21 and this with a protecting space I42 which is confined within the housing I38 and in communication with .the jacket space MI.

The condenser housing I38 also encloses the pump I23 as well as a pressure pump I45 which is located alongside oi the pump I23 and which communicates with the interior of this jacket space. Pump I45 leads to any suitable source of sterile gas for 'the protecting chambers. This gas may be the sterile air, other non-condensing gas, or pure steam which is also used in the can and cover section of the apparatus hereinbefore explained.

At the lower end of the vacuum pan the enend is directly connected with the spaced jacket controls the amount of milk passing through the nation of the product and any contaminating action to the interior of the pipes, vacuum pan,

, etc., which might be caused by leakage of the apparatus. To insure against such contamination the various pipes and vacuum pan condenser, etc., are enclosed within sealed jackets which may be maintained at an absolute pressure at all times greater than the outside atmospheric pressure.

The vacuum pan I05 is surrounded by a casing I3I (Fig. 2) the walls of which'are spaced from the outer walls of the vacuum pan members I01, I08, I09 and an enclosing housing I32 is also provided around the pipe 91 adjacent the vacuum pan. This housing I32 is connected with the housing I3I and provides for intercommunication'with the protecting space I35 which sur rounds the vacuum pan and with an auxiliary space I36 which surrounds the pipe 91. The manipulating handle of the valve I05 is extended through the wall of the housing I32 and the stem of the handle is properly packed in a sealed joint to prevent any'leakage around the valve stem.

A tubular housing I31 is'also provided to surround the header pipe I2I leading to the condenser I22 and this housing is bolted to the vacuum pan housing I3I. A protecting housing I38. is also provided for surrounding the condenser I22 and this housing is hermetically secured to the endof the housing I31. This provides a jacket space I4I surrounding the pipe HI and communicating on one side with the vacuum pan space I35 and at the condenser end wall 33 surrounding the filling chamber 21. The housing I48 encloses a confinedjacket space I48- which communicates with the jacket space I41 at one end and with the protecting space 34 of the filling chamber at the other end.

Where the heating coil II3 passes into the vacuum chamber of the vacuum pan, the'pipes H4, H5 are suitably packed and this also applies where they extend through the casing I3I sur-.

rounding the vacuum pan. In a similar manner the operating shaft of the pump I26, which is designated by the numeral I5I, is suitably packed where it extends through the wall I45 of the enclosing housing. v

The pump shaft I5I may carry a drive pulley I52 to which operating power may be applied in suitable manner as by a drive belt I53. The hand Wheel of the valve I28 is located exterior of the housing I48 and where the valve stem extends through the housing wall a suitable packed joint is provided.

By reason of the intercommunication of the jacket chambers I35, 535, Ml, I42, 31 and I49, the entire space surrounding the various units of the evaporating apparatus are confined and may be maintained .at a desired absolute pressure. This creation and maintenance of an artificially controlled atmosphere is preferably eiiected by the pump 545.

The amount of absolute pressure maintained in these jacket spaces is always slightly greater than that existing outside the apparatus in the atmospheric air. Thus bacterial contamination is prevented from entering into the product or into the interior of the working parts of the apparatus concerned with heating or sterilization, with evaporation or condensation of the milk. This example of a treatment of milk,

which requires a treating chamber at a reduced be done by treating the chambers with saturated steam under pressure. The surrounding jackets will also be sterilized before operation begins.

With a created, confined and regulated surrounding and protecting sterile atmosphere, any pressure desired in any treating chamber may be used irrespective of the normal outside atmosphere. In other words, there are no limiting circumstances relating to a desired treatment which cannot be successfully adjusted and used where a protecting zone of controlled sterile atmosphere is available according to the teachings of the present invention.

It is thought that the invention and many of its attendant advantages will be understood from the foregoing description, and it will be apparent that various changes may be made in the steps of the process described and their order of accomplishment without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the process hereinbefore described being merely a preferred embodiment thereof.

I claim:

1. A method of treating a sterilized product preparatory to canning, which comprises passing the sterilized product into a sealed chamber, maintaining about the product and in said chamber a sterile atmosphere, and surrounding said chamber with a confined and controlled sterile atmosphere of greater absolute pressure than the pressure within said chamber and greater than atmospheric pressure.

2. A method of treating a sterilized product preparatory to canning, which comprises passing sterilized product into, a sealed chamber, maintaining about the product and in said chamber a sterile atmosphere having an absolute pressure not greater than atmospheric pressure, and surrounding said chamber with a confined and controlled sterile atmosphere of greater absolute pressure than atmospheric pressure.

3. A method of treating sterilized products preparatory to canning, which comprises passing product into a sterilizing chamber, sterilizing the product, passing the sterilized product into a can filling chamber, maintaining about the product and the can parts in said filling chamber a sterile atmosphere having absolute pressure not greater than that of the natural atmosphere outside of the apparatus, and surrounding said filling chamber with a confined sterile atmosphere of greater absolute pressure than that of the natural atmosphere outside of the apparatus. a 4. A method of canning which comprises passing a sterile product to be canned into a sterile filling chamber, passing a sterile can-into said filling chamber, filling the product into the can while in said filling chamber, transferring the filled can into a sterile can closing chamber, hermetically sealing the filled can, and surrounding said closing and filling chambers and the I 'intercommunication therebetween with a confined sterile atmosphere of greater absolute pressure than that of the natural atmosphere outside of the apparatus. I

5. The method of treating liquiform products which comprises sterilizing the product, passing the product into a vacuum pan, maintaining a vacuum in the pan, withdrawing the sterile liquid from the vacuum pan, and protecting the liquid against contamination by surrounding the vacuum pan with a confined sterile atmosphere under pressure which is in excess of the pressure of the natural atmosphere outside of the apparatus.

' CHARLES 0. BALL.

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