WO2003024804A1

WO2003024804A1 - Vacuum gas flush packaging machine

Info

Publication number: WO2003024804A1
Application number: PCT/NZ2002/000178
Authority: WO
Inventors: Christopher Hugh Caudwell
Original assignee: Sealed Air (New Zealand) Limited
Priority date: 2001-09-14
Filing date: 2002-09-13
Publication date: 2003-03-27

Abstract

A vacuum gas flush packaging machine for packing product into flexible containers. The machine includes a chamber 13 in which one or more containers B can be located. A vacuum source VS for evacuating the chamber 13 and containers B. The container B is coupled to a nozzle 18 through which gag from agas supply GS can flow into the container B. A process control unit PLC controls via a controllable valve 30 the amount of gas to be supplied to the container in response to the weight of the container as read by a weighing device W.

Description

TITLE OF THE INVENTION

VACUUM GAS PLUSH PACKAGING MACHINE BACKGROUND TO THE INVENTION

This invention relates to vacuum packaging machines and more particularly to a vacuum chamber gas flush machine. Such machines are typically used for the packaging of products which are prone to spoilage and are thus used, for example, in the meat industry for packaging meat primals or consumer packs with the intension of extending the shelf life of the meat products.

It is known to provide a single chamber vacuum packaging machine whereby a spoilable material is placed in a flexible container which is in turn positioned within the chamber. The flexible container is subject to sub-atmospheric pressure within the chamber. The chamber itself is connected to a vacuum source. Consequently, both the chamber and the bag are evacuated.

Once the evacuation of the flexible container has been completed the container can be sealed, this sealing taking place within the chamber and before the chamber is opened. Prior to the flexible container being sealed it can be gas flushed i.e. the flexible container refilled with a volume of gas (e.g. carbon dioxide) in a controlled amount.

One example of a single chamber vacuum packaging machine can be found in New Zealand patent specification 2188186/221180. The packaging machine of this patent specification is described as also including a gas flush function. It is necessary that the volume of gas injected into the flexible container be a known ratio to the weight of the product (which will hereinafter, for convenience, be referred to as "meat") in the container. There is generally known a volume of gas per weight of meat. However, differing ratios are sometimes used especially a lesser ratio when a shorter product life is acceptable.

The weight of meat naturally varies from package to package (cut to cut) . However, with existing machines the volume of gas is preset prior to a production run to ensure that sufficient gas is used for the heaviest packs. If a significantly lighter pack is included in a production run the machine must be stopped and the gas level reset before and after the light pack is processed through the machine. This results in time wastage. Thus to avoid this problem it is known to package only meat of a particular type or weight, e.g. lamb legs, until the run is complete and then package on the next run, meat of a different type or weight e.g. lamb shoulders .

This procedure necessitates the storage of meat cuts until the machine is reset for the next type of cut or the next weight range of cuts. Not only does this raise issues involving storage of the cuts until the machine has been reset, but also there are issues such as double handling and hygiene which can significantly reduce the storage life of the product. SUMMARY OF THE INVENTION

An object of the present invention is to provide a vacuum chamber gas flush packaging machine which exhibits improved control of the air removal and gas flushing process.

A further object of the present invention is to provide a vacuum chamber gas flush packaging machine whereby the volume of gas to be injected into a flexible container can be readily, preferably automatically, adjusted to achieve the desired ratio of gas to the weight of the content of the flexible container.

According to a broad aspect of the invention, there is thus provided a vacuum chamber gas flush packaging machine including a chamber in which one or more containers can be located, an evacuation means by which the chamber and the or each container can be subjected to sub-atmospheric pressure, coupling means to couple the or each container to a gas supply, weighing means to weigh each container, and control means to control the quantity of gas to the container in response to a weight reading device from said weighing means.

In a preferred arrangement the weighing means weighs each container before it is located in the chamber.

According to a preferred embodiment of the invention there is provided release means whereby relative movement between a container and the coupling means to which it is coupled can occur such as to assist in the release of the container from the coupling means. According to a preferred embodiment compressed air is released from the coupling means at completion of sealing of the container to assist removal of the container.

According to a preferred embodiment of the invention there is provided height adjustment means whereby the height of a container within the chamber can be adjusted.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following more detailed description of the invention, according to a preferred embodiment, reference will be made to the accompanying drawings in which: -

Figure 1 is an elevation view,

Figure 2 is a plan view,

Figure 3 is a somewhat schematic view but showing the chamber in cross-section, and

Figure 4 is a schematic transverse cross-section through the chamber of the machine, and

Figure 5 is schematic layout of the gas flush plumbing.

The machine 10 includes a main frame 11 to which is moveably mounted a cover 12. The cover 12 is, in the preferred form of the invention, moveable under the control of a number of linear actuators R generally one being located at or adjacent each corner of the cover 12. For example, the bodies of the linear actuators can be fixedly mounted with the frame 11 and the ends of the piston rods P attached to the cover 12. The cover can thus be raised and lowered relative to the frame 11. In Figures 1 and 3 the cover is in the lowered position.

The cover 12 defines a chamber 13. Extending above the floor 15 of the chamber 13 is, in the preferred form of the invention, one or as shown in Figure 2 a pair of conveyors 14 which extend longitudinally within the chamber 13. For ease of reference the conveyors 14 will be simply referred to as a chamber conveyor 14.

An in-feed conveyor 16 extends toward the cover 12 with its output end located closely adjacent (outside the cover) to the chamber conveyor 14 located within the chamber. In a like manner an output conveyor 17 extends away from the cover 12 with its input end closely adjacent the output end of the chamber conveyor 14.

Projecting upwardly from the floor 15 is one but more preferably a series of nozzles 18. In one form of the invention each of the nozzles is connected by a conduit 19 to a vacuum source VS (see Figure 3) . The nozzle 18 is connected by conduit 19 to the vacuum source VS via a valve 20 (also see Figure 3) .

According to an alternative form of the invention the nozzle 18 is not connected to the vacuum source VS. In this form the mouth of a flexible container engaged with the nozzle is not fully sealed about the nozzle. Thus the container is open to sub-atmospheric pressure in the chamber whereby the flexible container is evacuated by the sub-atmospheric pressure in the chamber. The nozzle 18 can be formed by a tubular member 18a which opens into an elongate chamber 18c which has a projecting mouth 18b having one elongate aperture or preferably a series of apertures. This preferred construction is such that the chamber mouth 18b can be likened in appearance to a mouth organ.

The vacuum source VS is also coupled via a valve 21 and conduits 22 to vacuum ports 23 opening through the floor 15. In the preferred form of the invention there are two ports 23. According to one form of the invention (as shown in dotted detail in Figure 2) these can be one at either end of the chamber 12. It is believed that these ports 23 will not only increase the speed of air evacuation and re-entry but also will eliminate the tendency with existing machines to shred flexible containers (e.g. metallised pouches) near to the port due to violent air motion. According to a second form as shown in Figure 2 the ports 23 will be located on the opposite side of the chamber to the seal bars to minimise the possibility of high speed air disturbing the container mouth.

In accordance with known techniques, a clamping arrangement (not shown) is provided within the chamber 13 for clamping the neck of the flexible container around the end of the nozzle 18. Using normal process control techniques, the clamping arrangement is operable (according to the form of the invention shown in Figure 3) to clamp, in a sealed manner, the neck of the flexible container about the nozzle once the cover 12 is lowered into the closed position. Likewise, the clamp arrangement is operable to release prior to the flexible containers being moved onto the output conveyor 17 by the chamber conveyor 14. As such clamping arrangements are well known within the art and do not form part of the present invention, further description herein is not required in order to provide a disclosure of the invention.

In the alternative form of the invention the flexible container B is not tightly sealed around the nozzle 18 during the evacuation stage. According to a preferred arrangement the nozzle 18 is arranged so that it can rise (relative to floor 15) and clamp the upper part of the mouth of the container against a top clamp C mounted to the roof of the cover 12. Thus, only part of the mouth of the container is clamped i.e. the rest of the mouth remains open so that the container is open to sub-atmospheric pressure in the chamber. By clamping the upper part of the mouth of the container the tendency for the top of the bag to pull back and disturb the surfaces which need to be ultimately sealed is prevented.

Likewise, there is provided within the chamber 13 a sealing arrangement associated with the or each nozzle 18 and hence the flexible container is associated with the nozzle. Such sealing arrangements are also well known within the art and are processed controlled so that the flexible container is sealed outward of the end of the nozzle 18 prior to the release of the clamping arrangement.

In accordance with known heat sealing mechanisms there is provided a seal anvil S¹ which is attached to the cover 12. An associated heat seal bar S is mounted and supported from the floor 15. This seal bar S is coupled to a linear actuator arrangement L3 which is in large part located outside the chamber. The linear actuator can thus be actuated to cause the seal bar S to rise and clamp the neck of the flexible container between the seal bar S and seal anvil S¹ so that sealing can take place.

Once the neck of the flexible container has been sealed the neck can be removed from the nozzle 18. This can be achieved by the conveyor 14 operating so as to move the bag relative to the nozzle. However, this does not always result in separation of the bag from the nozzle thus it is preferred to have an arrangement whereby the neck is positively pulled off the nozzle, there is a positive relative movement between the nozzle and container resulting in the neck parting from the nozzle .

Different arrangements have been devised for achieving this positive relative movement between the nozzle and the container. These different arrangements include but are not limited to the arrangements which are hereinafter described.

In one embodiment the operating mechanism L3 for the seal bar S will cause the seal bar to rise simultaneously with the cover 12. This has the effect of keeping the neck N of the flexible container B clamped between the seal bar S and the seal anvil S¹. In this way the neck N of the flexible container B is pulled off the nozzle 18.

As the cover 12 continues to rise it will move the seal anvil S¹ to a height greater than the maximum height to which the seal bar S can be raised by linear actuator arrangement L3. This thereby causes the anvil S¹ and seal bar S to part thus releasing the neck N of the flexible container B. The flexible container B is thus free of the nozzle 18 for it to be removed from the confines of the chamber 13 and onto the output conveyor 17.

In a yet further embodiment the nozzle 18 can be moved horizontally by rotating the tubular member 18a through sufficient angle. This removes what effectively is the trailing edge of the nozzle 18 from the bag B so that as the bag moves sideways i.e. in the direction of travel of chamber conveyor 14 relative to the nozzle it does not catch on the end of the nozzle. It is the catching of the bag, or more particularly the neck of the bag on the nozzle, which can often result in the bag failing to separate from the nozzle.

In a preferred arrangement the nozzle is arranged such that it is moveable in an upward direction relative to the floor 15.

This can be achieved by the tubular member 18a extending through an opening in the floor 15. The end of the tubular member 18a located outside the chamber is coupled to a linear actuator LI. In the preferred form the piston rod R of the linear actuator LI is coupled to the lower end of the tubular member 18a which the body R¹ is held in a fixed position. A sealing 0 ring or like seal is located between the tubular member 18a and the periphery of the opening in the floor 15 to provide a seal so that the chamber is sealed when the cover is in the closed position.

As a consequence with suitable process control the seal bar S and anvil S¹ can clamp the neck N of the flexible container B during the sealing operation whereupon the nozzle 18 can then be caused to rise relative to the floor by linear actuator LI. this movement causes the nozzle 18 to move upwardly relative to the clamped neck N of the flexible container to create a positive pulling of the nozzle 18 from the neck N of the container B. The container is thus free of the nozzle 18 prior to the seal bar S and anvil S¹ releasing. Hence separation of the nozzle and container occurs before the container is moved by the chamber conveyor 14 from the chamber.

This rising arrangement for the nozzle 18 could also be achieved by having a passageway through the centre of a linear actuator or at least through the centre of the piston rod. A conduit 19 will be connected to the internal wall or passageway of the linear actuator so as to connect the end of the nozzle with the vacuum source VS.

For reasons which will hereinafter become apparent it is believed that the arrangement of causing the nozzle 18 to rise and lower provides advantages and, therefore, is the preferred arrangement for providing a positive release of the nozzle and flexible container.

The aforesaid arrangements will ensure that following completion of a vacuum gas flush cycle (as hereinafter described) the flexible containers will be positively pulled off the nozzles 18. This thereby enables the machine to operate automatically and continuously i.e. without the need for the machine to pause or cease operation for a period of time to enable an operator to check that each flexible container B has released from its nozzle 18.

By having a conveyor 14 which is principally located within the chamber 13, it is possible to arrange the conveyor so that the height of the conveyor 14 within the chamber 13 can be adjusted. This will provide for fast change over from one pack size to another and avoid the need for smaller packs to pass through the machine placed on some form of pedestal to bring them up to a fixed seal bar height. Conveyor height adjustment can be achieved by having a vertical moving plate inside the chamber. To achieve this each end of the conveyor will extend (about 270mm) outside the chamber 13 either side. This external extension is to provide for detensioning and roller mechanism so as to enable the belt to be lifted.

The height adjustment can be incremental or continuous in its adjustment. When incremental it is envisaged that say two or three different positions will be used with adjustment by a two or three position switch to be operated by an operator so as to place the chamber conveyor 14 at the height required.

It is intended to have the belt of chamber conveyor 14 going under the lid seal as shown in the drawings. However, it is proposed that the belt could be fully located inside the chamber.

An advantage of having a chamber conveyor 14 principally located within the chamber 13 is that sealing problems associated with existing machines, where a single conveyor passes through the machine, can be overcome. Consequently, with a fully contained conveyor there will be no conveyor belt trapped within the lid seal.

To now more fully describe the invention, reference will be made to the operation of the machine (according to its first form) in a typical cycle. This description of the operation will, for the sake of simplicity, be directed to a single nozzle 18 to which is attached a bag B by clamping means (not shown) . Commonly the package consists of one or more lamb legs inside a large pouch or bag which in turn sits inside a cardboard carton. In Figure 3 only the bag B is shown.

The bag B is conveyed via input conveyor 16 onto the chamber conveyor 14. It is conveyed to the nozzle 18 by chamber conveyor 14. An operator then places the mouth of the neck N of the bag B over the nozzle 18. The neck is clamped onto the nozzle by a clamping mechanism which includes a top clamp anvil attached to the inside of the cover 12. This anvil will thus descend with the cover 12 to meet with a lower clamping anvil mounted on the floor 15.

When the cover 12 is lowered and seals at the lower end the cover 12 engages with a sealing surface including floor 15 to thereby form a closed chamber 13. Valves 20 and 21 are opened so that the bag B and chamber 13 are respectively coupled to the vacuum source VS. Evacuation of both thus commences. However, the arrangement is such that the chamber 13 evacuates at a quicker rate than the bag B thereby creating a pressure differential which causes the bag to "balloon"^'. This arrangement, which causes the bag to balloon, is in accordance with known techniques .

After a predetermined time, as determined by timer T, the chamber 13 will have evacuated to a desired level whereupon valve 21 is closed. In the preferred form of the invention a pressure sensor 24 can be coupled to the chamber 13 or more particularly at some point in conduit 22 to sense the pressure within the chamber 13. This pressure sensor 24 can be operably coupled to a display/warning device 25. Accordingly the operator can be alerted either visually and/or aurally to the fact that the chamber 13 has not evacuated to the required level. The warning device will generally form part of a control console C.

The bag B will continue to evacuate. A pressure transducer 26 is coupled to the nozzle conduit 19 and thereby determines the vacuum level within the conduit 18 and hence the bag B. This transducer 26 is operatively coupled via line 26a with valve 20.

Connected to the floor 15 and opening into the chamber 13 is a vent valve 27. In the preferred form of the invention the vent valve 27 is operated by solenoid 28. In Figure 3 the vent valve 27 is, for convenience of drawing, shown connected to the cover 12.

The solenoid 28 is caused to operate while bag B is still being evacuated. The venting of the chamber 13 will thus result in a consequential rapid collapsing of the bag B. This collapsing of the bag will force out any remaining air and, more particularly, will force out any water vapour or moisture which may be present in the bag. Generally, some water vapour or moisture will be present in the bag as a consequence of the chamber pressure having fallen below boiling pressure of water at ambient temperature. As the first valve 20 remains open while this occurs any residual air/vapour from the nozzle (and the conduit 19) will be cleared prior to the valve 20 closing.

According to the second form of the invention as disclosed above the bag B is not separately connected to the vacuum source VS. This does away with the need to connect conduit 19 of the nozzle 18 via valve 20 to the vacuum source VS. As explained previously the arrangement is such that the mouth of the bag is only partially clamped to the nozzle 18. As disclosed this can be achieved according to one form of the invention by arranging for a clamp bar e.g. clamp bar C attached to the roof of cover 12 to move toward to the nozzle 18 as the cover 12 descents. Thus when the cover 12 lowers to its fully closed position the clamp bar C locates a distance from the nozzle 18. The nozzle 18 is then raised by actuator L2 so that the clamp bar C comes into engagement with and clamps with nozzle 18 that part of the mouth of the bag B engaged on the nozzle 18. This results in the remainder of the mouth being undamped.

Consequently, as the chamber 13 is evacuated the sub- atmospheric pressure within the chamber also causes evacuation of the bag B to occur. Following evacuation a further clamp C¹ engages with and seals the remainder of the mouth of the bag B around the nozzle 18. This further clamp C¹ is movable up and down by linear actuator L2 in the same manner as previously described for linear actuators LI and L3. It will be appreciated that when the seal bar S and further clamp C¹ are common for a plurality of nozzles 18 (as per Figure 2) there may be a plurality of linear actuators L2 and L3 acting on the clamp C¹ and seal bar S. This sealing step of course occurs before the gas flush operation commences. This ensures that the calculated charge of gas flows fully and only into the bag B.

The formation and evacuation of gaseous water from free moisture in the product during the evacuation phase assists in the removal of oxygen from the bag B since the partial pressure of oxygen is reduced.

A gas supply GS (e.g. carbon dioxide or a mixture of carbon dioxide and other gases) is coupled via a gas isolation valve Vi to a gas reservoir 31. A pressure regulator 29 is coupled to the gas reservoir 31 which via a controllable valve 30 in conduit 19 controls the flow of gas to nozzle 18 (see Figure 5) . The pressure regulator 29 is incorporated so as to ensure that a constant gas pressure is achieved. Valve 30 is coupled to control unit PLC via line 30a.

After the evacuation stage has been completed, the controllable valve 30 is opened so that gas flushing via the conduit 19 and nozzle 18 occurs.

In an alternative arrangement, operation of the vent valve 27 can be controlled so that it is responsive (via line 27a) to a pressure reading from the pressure transducer 26. With such an arrangement the vent valve 27 can be controlled so that it firstly vents the chamber 13 and then after it has closed the second valve 21 is reopened so that a level of vacuum is pulled in the chamber 13. This will cause the bag B to slightly distend prior to, or at the time of gas flushing. The chamber 13 can then be re-vented before the chamber is opened.

According to the preferred form of the invention weighing means W are associated with, or form part of, the input conveyor 16. In accordance with known techniques one or more local cells are located below and in contact with the belt of the input conveyor. Thus, incoming packages are each individually weighed on the weighing means W and indexed onto the chamber conveyor 14 so that the weight of product in each bag is known. The weighing means is coupled to the control unit PLC. Using process logic techniques the weight of product in each bag is used to calculate the volume of gas required for each bag.

Consequently, when the gas flushing operation takes place under control of the control unit PLC the required volume of gas is supplied to the bag. The optimum volume of gas being supplied to the bag ensures that there is no gas wastage and that the product within the bag will be assured of its required extended shelf life. Essentially the process logic control PLC will adjust the time that controllable valve 30 remains open and as a consequence of the constant pressure of the gas being supplied from the gas supply GS the correct volume of gas required for the bag B can be controlled.

Throughout the preceding disclosure the terms "flexible container" and "bag" have been used. It is to be understood that these terms cover different forms of packs and packaging and in particular a semi-rigid outer within which a flexible pouch containing the product is located. The present invention is, therefore, not limited to any particular form of flexible container, bag or the like.

The present invention provides a method and means whereby the volume of gas to be supplied by the flexible container in the gas flushing operation is tailored to suit the weight of product within the bag, thereby not only ensuring that the required volume of gas is supplied to the bag but also better economics are achieved by obviating or at least lessening gas wastage.

There are, however, further advantages arising out of the automatic adjustment of the gas volume.

One of these further advantages is that following the packaging process the flexible container is necessarily distended with gas. If the gas is C0₂ and the product is meat then the C0₂ is absorbed into the meat over a period of one or two days. During this time it is usual practice to hold the package in a chiller to lower the meat temperature to slow bacteria growth and also to speed gas absorption.

Because of the distended nature of the flexible containers it is not possible to fully close the outer rigid container

(normally a cardboard carton) . This means that it is not possible to place the packages in, for example, a sea freight container. By ensuring that no more gas than necessary is used the invention minimises the time delay before the outer rigid container can be fully closed and sealed. This minimisation of the time delay flows into a reduction in the cost involved before the product can be shipped.

Also automation of the gas volume simplifies the program required to control the machine. Only one program is required. However, with known machines it is necessary to manually insert a series of instructions into the controller. Each of these instructions is designed for a particular packaged format. Control and selection of these instructions to meet changing package weights has required both time delays and the opportunity for human error. These disadvantages are removed by the automatic gas volume control of the present invention which as stated above only requires one programme for control of the machine for varying product formats.

The present invention also provides two means for ensuring that there is positive removal of the neck of a container from the nozzle to which it is connected. Firstly the nozzle rises at the completion of the sealing process as described previously. Secondly compressed air can be released through the nozzle to blow the container clear. Thus for example and as shown in Figure 5 a conduit 32 connects nozzle 18 to a breathable air connection 33. In the conduit 32 is a controllable air blast valve V₂ which is operable by the PLC to permit the blast of air to the nozzle to take place.

Once again, this reduces time delays and also reduces the possibility of damage to container or equipment which could result from a container failing to separate from a nozzle. This feature is of particular benefit where narrower flexible containers are used. This invention aids the use of narrower and, therefore, less expensive flexible containers.

As illustrated in Figure 5 a "sniffer" is also provided in order to sense the level of oxygen which may remain in the bag B following evacuation. This, in accordance with known techniques, enables the PLC to ensure that correct evacuation has taken place.

Thus an oxygen analyser sensor module 34 is connected to a vacuum connection 35. The module 34 is connected via conduit 36 to an analyser sample head 37. The sample head 27 is coupled via line 38 to a sample port 39 in the nozzle 18. A controllable valve V₃ in line 38 is operable by the PLC to enable operation of the oxygen sensor module.

Also, in an effort to not only improve the handling of different sized container but also to cut down in processing delays the present invention provides for product height adjustment within the chamber so as to accommodate different packs/containers .

The packaging machine is open to modification. For example the machine throughput can be increased by using gusseted bags which lie transverse on the chamber conveyor 1 relative to the direction of travel (as opposed to the longitudinal orientation of the containers as described herein) . Thus more bags B can be handled during an operation cycle. To this end the machine will be modified to incorporate further nozzles 18. This is achievable because the length of the elongate mouth organ part of the nozzle can be reduced as a consequence of the use of gusseted bags.

It is, therefore, believed that the present invention provides a method and means which results in particular improvements and advantages over methods and means of vacuum and gas flushed packaging. It will be appreciated by those skilled in the art that the invention is open to modification within the scope and spirit of the invention and that the foregoing provides examples only of different embodiments of bringing the invention into effect.

Claims

CLAIMS : -

1. A vacuum chamber gas flush packaging machine including a chamber in which one or more containers can be located, evacuation means by which the chamber and the or each of container can be subjected to sub-atmospheric pressure, coupling means to couple the or each containers to a gas supply, weighing means to weigh each container, and control means to control the quantity of gas to the container in response to a weight or reading device from said weighing means.

2. The machine as claimed in claim 1 wherein the weighing means is positioned outside the chamber.

3. The machine as claimed in claim 1 wherein the chamber evacuation means also is the means for evacuation of the container.

4. The machine as claimed in any one of the preceding claims further including release means whereby relative movement between a container and a coupling means to which it is coupled can occur such as to complete the release of the container from the coupling means .

5. The machine as claimed in claim 4 wherein there is further provided means for supply of compressed air to the coupling means at completion of sealing of the container to assist removal of the container from the coupling means.

6. The machine as claimed in any one of the preceding claims further including height adjustment means whereby the height of a container within the chamber can be adjusted.

7. The machine as claimed in any one of the^" preceding claims wherein the coupling means includes a nozzle which is connected via valve means to a gas supply.

8. The machine as claimed in claim 7 wherein the nozzle is further connected to a sub-atmospheric pressure source.

9. The machine as claimed in claim 8 wherein the coupling means further includes clamping means for clamping in open mouth of the container in the sealed manner to the nozzle.

10. The machine as claimed in any one of the preceding claims further including a sealing arrangement within the chamber for sealing closed the flexible container prior to release from the coupling means.

11. The machine as claimed in claim 10 wherein the or part of the sealing arrangement is moveable relative to the coupling means to effect removal of the flexible container from the sealing means.

12. The machine as claimed in claimed 11 further including means to release the sealing arrangement following release of the container from the coupling means.

13. A vacuum chamber gas flush machine including a chamber formed in part by a closeable cover, evacuation means by which the chamber can be evacuated, at least one nozzle located within the chamber and connected to a gas supply, first clamp means to partially clamp the mouth of a flexible container to the nozzle, second clamp means to sealingly clamp the mouth about the nozzle after evacuation of the chamber has occurred, weighing means to weigh the container, control means to control the quantity of gas to the container in response to a weight determined by the weighing means and sealing means to seal closed the neck of the container after the quantity of gas has been supplied to the container.

14. The machine as claimed in claim 13 wherein the weighing means is positioned to weigh each container before it is located in the chamber.

15. The machine as claimed in claim 13 or 14 wherein the sealing means is moveable relative to the nozzle at the completion of sealing of the neck.

16. The machine as claimed in claim 13, 14 or 15 wherein the nozzle is moveable relative to the first clamp to effect the partial clamping of the ^■• container mouth to the nozzle.

17. The machine as claimed in any one of the preceding claims further including a positive pressure air flow to the sealed mouth of the container to assist release of the mouth from the nozzle.

18. The machine as claimed in any one of the preceding claims including conveyor means extending within the chamber for conveying the containers to and from the nozzle (s), said conveyor means being height adjustable relative to the nozzle (s) .

19. The machine as claimed in anyone of the preceding claims wherein the weighing means incudes one or more load cells associated with an input conveyor on which a container resides prior to being delivered by said input conveyor to the chamber.