Abstract:
A pressurized gas container associates with and supplies gas to a pressurized gas port of an appliance, such as for supplying carbon dioxide for the preparation of a carbonated drink. The container has a plug at its opening that has a barrier element that seals the container and is configured to be non-reversibly ruptured by a shaft of a gas-channeling member. The plug also has one or more sealing elements that are distinct from the barrier element and are configured for forming a gas-tight association with the shaft of the gas-channeling member. A plurality of such pressurized containers may be carried by a holder rack in a multipack. An appliance adapted for preparing or dispensing carbonated drink includes an adapter for associating with such a pressurized carbon dioxide-containing canister and for receiving the pressurized carbon dioxide therefrom.

Description:
TECHNOLOGICAL FIELD 
       [0001]    The present disclosure concerns a pressurized gas container, for example one containing carbon dioxide for use in a device or system for the preparation of a carbonated drink. The present disclosure also provides a plug that may be functionally integrated into the container and further provides a packaging with a plurality of such containers. 
       BACKGROUND ART 
       [0002]    References considered to be relevant as background to the presently disclosed subject matter are listed below:
       GB 2,176,586   U.S. Pat. No. 3,587,926   U.S. Pat. No. 3,684,132   TW M370038       
 
         [0007]    Acknowledgement of the above references herein is not to be inferred as meaning that these are in any way relevant to the patentability of the presently disclosed subject matter. 
       BACKGROUND 
       [0008]    Pressurized gas containers are typically used in systems or appliances that require in-feed of pressurized gas. An appliance for the preparation of a carbonated beverage is one such example. Most pressurized gas containers are designed for multiple use, i.e. the container&#39;s volume and/or gas pressure are sufficient for several gas-feed doses. This typically requires the container to be associated with a mechanism allowing connecting and disconnecting gas flow between the container and the appliance or system. Often, the container itself is equipped with a gas-flow control mechanism, such as a valve or a re-sealable membrane, to permit a user to disconnect the container from the appliance or the system while preventing gas leakage from the container. 
         [0009]    In addition, the containers are often designed for multiple use cycles, i.e., once the container is emptied, it is often shipped back to the provider for cleaning and re-filling. Such a container is typically designed to meet strict safety requirements, such as relatively thick wall thickness and robust re-sealable opening in order to minimize accidental rupturing of either the seal or the container. This, however, results in high production costs and complex logistics. Moreover, many such containers are not returned after utilization to the supplier for re-filling, resulting in relatively high sunk-costs. 
         [0010]    There is therefore a need for disposable pressurized gas containers which are intended for a single use in an appliance or a system, such as an appliance for the preparation of a carbonated drink. 
       GENERAL DESCRIPTION 
       [0011]    Provided by an aspect of this disclosure is a new pressurized gas container, in particular but not limited to a pressurized carbon dioxide canister for use in appliances or systems for the preparation of carbonated drinks The new container is intended for single use, meaning that it may be used until its content of pressurized gas is exhausted and then discarded, e.g. disposable after use. For example, a carbon dioxide canister of this disclosure is coupled to a system or appliance and may be used for preparing multiple carbonated drink portions and then decoupled from the appliance or system and discarded. Accordingly, the container has a plug at its opening (the opening typically formed at end of a neck portion of the container) that is configured for (i) sealing the opening until use of the container, (ii) irreversibly opening, piercing or rupturing upon coupling of the opening with a coupling element (also referred to herein, occasionally, as “adapter”), which may be an integral element of the appliance or system or may be or a coupling device (an adapter) for coupling to the container&#39;s opening on the one hand and to the appliance or system on the other hand to thereby establish gas communication between the container and said appliance or system, and (iii) thereafter permitting the release of the pressurized gas from the container into a gas port of said appliance or system. The container&#39;s body may be formed with walls having an average thickness that is less than that of containers intended for repeated use, where the walls need to meet higher safety standards to withstand the many repeated cycles of filling the container with pressurized gas and subsequent emptying. 
         [0012]    The mode of use of prior art pressurized gas containers that involves multiple filling and emptying cycles (“multiple use container”) mandates high safety standards, which include, among them, robust construction standards manifested, among others, in certain wall thickness requirements. In the case of a container of the kind provided by this disclosure, the container body may have walls with an average thickness that can be 60%, 55%, 50%, 45%, 40% or at times even less of the average thickness of the walls of a container body of a multiple use container. This may lead to a considerable saving in weight and costs. 
         [0013]    Other aspects of this disclosure include: 
         [0014]    a plug device that may be integrated with a container blank to form the pressurized gas container of this disclosure; 
         [0015]    a container blank that may be integrated with said plug device to form the pressurized gas container of this disclosure; 
         [0016]    a method for the preparation of such container, comprising filling the blank with pressurized gas and then sealing the opening of the container with the plug device; 
         [0017]    an apparatus for such manufacture for carrying out said method; 
         [0018]    an adapter for coupling a pressurized gas container to an appliance or system; 
         [0019]    multipack of pressurized gas containers, which may also comprise such an adapter; and 
         [0020]    an appliance or system for utilizing the pressurized gas containers of the invention, e.g. an appliance or system for preparing carbonated drink. 
         [0021]    Thus, provided by an aspect of this disclosure is a pressurized gas container or canister (jointly referred to herein as “container”) in particular (but not exclusively), one containing pressurized carbon dioxide. The pressurized gas container of this disclosure may be configured for use in an appliance or system adapted for the preparation and optionally dispensing of carbonated drinks The container is, typically, one that is intended for association with a carbonated drink dispensing appliance or system in which the pressurized carbon dioxide is utilized for the preparation of the carbonated drink Thus, the pressurized gas container is intended for association with and supplying gas to a pressurized gas port of an appliance or system. Another example of container that may be employ the principles of the current disclosure is a container filled with pressurized air, oxygen or other breathing mixture for use by firemen, by high-altitude mountain climbers, as a bailout breathing canister for scuba divers; etc. The container comprises a container body, defining a pressurized gas enclosure, and a neck integral therewith that defines a gas outlet and is configured for coupling with a coupling element. The coupling element may be a coupling element integral with or forming part of said gas port or may be a coupling element of a coupling device or adapter configured for coupling with said port, to permit the release of gas into a pressurized gas port of said appliance or system. The term “coupling element” will be used to refer collectively to a coupling element which is integral with or part of an appliance or system and a stand-alone coupling device for coupling between a container and the appliance or system. The neck is fitted with a plug. The plug has a gas-impermeable barrier element sealing said enclosure and configured for irreversible opening through rupture, piercing, deformation or displacement (to be referred to, collectively, as “irreversible opening”) by a shaft of a gas channeling member of said coupling element that extends from a base to an end, which may be tapered or spiked. The plug also has one or more sealing elements, which are distinct from said barrier element, and are configured for forming a gas-tight association with said shaft to thereby block gas leakage after coupling. 
         [0022]    Typically, in order to ensure that it will not be undesirably ruptured, deformed or displaced, the barrier element should be designed to withstand pressure higher than that of the intended gas pressure inside said enclosure. Furthermore, for safety reasons, the barrier element should be designed to have a defined burst threshold pressure that will cause the barrier element to burst open. This may avoid danger in the event of pressure build-up within the container, e.g. as a result of exposure to excessive heat. 
         [0023]    By an embodiment of this disclosure, the plug in the pressurized gas container is formed with a bore that is fitted with a gas impermeable barrier element for forming a gas impermeable barrier between the pressurized gas enclosure and said bore. The barrier element can be non-reversibly opened by a shaft of a gas-channeling member, extending from a shaft base to a shaft end, the shaft end that penetrates the cavity during association of the neck with the coupling element, and during this penetration it causes the barrier element to irreversibly open. Once irreversibly opened, gas can flow past the now opened barrier element. The shaft end may be tapered, spiked or pointed, to facilitate rupturing or breaking of barrier. The bore, however, is also configured with at least one sealing element, typically one or more O-rings disposed proximal to the bore&#39;s exterior end or in between the barrier element and said exterior end, adapted for forming a gas-tight association with said spiked member, thereby hindering undesired gas leakage through said bore. The shaft of the gas-channeling member has one or more openings at a location proximal to its end such that, following complete penetration of said shaft and thereby causing the irreversible opening of the barrier element, are in gas communication with said enclosure; namely the opening are at the shaft&#39;s free end or in between said free end and the point of contact with said at least one sealing element. The openings lead into a gas-ducting lumen formed within the shaft that channels the gas into the pressurized gas sub-system of the appliance or system. Thus, once the barrier element is opened, the gas can flow through the openings and the gas-ducting lumen into the pressurized gas sub-system of the appliance or system for use therein. 
         [0024]    By an embodiment of this disclosure, the barrier element is a pierceable solid element, e.g. a sheet, thin plate, film, etc. (to be referred to herein, collectively, as “pierceable element”), which may, for example, be made of metal or a plastic material. The pierceable element should be able to withstand pressure at least equal to (or slightly more than) the intended pressure of the gas inside the container. 
         [0025]    By another embodiment, the barrier element is constituted by a displaceable or deformable plug or leaf, typically made of an elastic material, which is maintained in a sealing state pressed against a plug seat and may be irreversibly displaced or deformed by the gas channeling spike member. 
         [0026]    By an embodiment of this disclosure, the plug is fitted into the container&#39;s neck, such that its bore is substantially coaxial (save for small manufacturing tolerance) with said neck. It should further be noted that this disclosure is certainly not limited to such coaxial configurations and the main features of this disclosure may also be embodied in other arrangements; for example, in a plug that is generally L-shaped with a cavity intended for coupling with a spiked member being normal to the axis defined by the neck. 
         [0027]    By an embodiment of the current disclosure, the plug is formed as a device to be fitted within the neck of a container blank. Such a device is also an independent aspect of this disclosure. In the following the term “plug” may be used to denote, depending on the context, either a plug within the container&#39;s neck or a plug device that is fitted/intended to be fitted into the neck. 
         [0028]    By an embodiment of this disclosure, the plug defines an axis extending between an exterior end and an internal end (e.g. having an overall cylindrical shape) and being formed with a generally axial bore extending between the two ends. Such plug is typically formed with a barrier at or proximal to its interior end and with one or more sealing elements formed within the cavity at or proximal to the exterior end or in-between the interior and exterior ends. The sealing elements, as already noted above, are typically O-rings that may be fitted within a circumferential groove formed within the wall of the cavity. 
         [0029]    The plug may be formed with an uneven external surface (i.e. non-uniform profile) which may serve for tighter engagement with surrounding portions of the neck into which the plug device is fitted. 
         [0030]    By one embodiment, the plug is pressure-fitted within the neck. This means that either the plug is inserted into the neck and the surrounding neck portion is then crimped over the side walls of the plug, or that a plug device is forcibly inserted into the neck thereby slightly deforming the upper end portion of the neck to ensure a pressure-tight fit. By another embodiment the plug is screw-fitted within the opening of the container. By yet another embodiment the plug is secured within the opening by welding. By still another embodiment the plug is secured within the opening by a combination of screw-fitting and welding, screw-fitting and pressure fitting or pressure fitting and welding. 
         [0031]    The plug device, according to an embodiment of this disclosure, comprises external walls and a bore formed within it and includes a barrier element and at least one sealing element of the kind specified above. 
         [0032]    By an embodiment of this disclosure the container comprises a flow-restricting element configured to permit (i) free flow of pressurized gas as long as the neck is coupled to the coupling element and (ii) limited outflow of gas upon decoupling of the coupling element from the neck. Thus, in the event that the container is detached from the coupling element of the system or appliance, the gas remaining in the container will not outflow in a rapid or violent burst but will rather be gradually released. The flow-restricting element may comprise a floating member (which may be rounded, e.g. ball-shaped) displaceable between a seated position in which it bears against a seat at an outlet of the container to thereby partially seal the container&#39;s outlet and an unseated position in which it is distanced from said seat and permitting free gas outflow through said outlet, said floating member being biased into said seated position and being configured for displacement into said unseated position by the shaft of said gas channeling member. The flow-restricting element is typically situated in a position interior to said barrier element and may comprise a nesting member fitted within the container&#39;s neck and having an upper segment defining said seat and a lower segment comprising arms configured to limit displacement of said floating member. In order to provide for a limited gas outflow, gas channels are typically defined in the flow-restricting element such that in the seated position of the floating member trickled gas outflow is enabled. By one configuration, such channels are defined in the seat. The floating element may be for a seal with the seat other than in portions in which such channels are defined. By another configuration the association between the floating member and the seat is such to permit some gas flow in a small gap between said member and said seat. For example, the seal or the member may have a rough surface to thereby define small gaps between the two to thereby permit trickled gas outflow. By yet another configuration channels are defined between the nesting member and the interior faces of the neck to facilitate gas outflow when the floating member is seated in said seat. The current disclosure also provides a multipack comprising (i) a holding rack, (ii) a carrying element, typically integral with the rack, and (iii) a plurality of pressurized gas containers, in particular, but not exclusive, a plurality of pressurized carbon dioxide-containing canisters, each of which is configured for coupling with said adapter (whether an integral part of an appliance or system or a coupling device), and once coupled, release gas into the pressurized gas port of the appliance or system. The holding rack may be configured as a case, box, etc., having a plurality of slots for holding the canisters and may be made of cardboard, plastic, or any other suitable material. The overall configuration of the multipack of this disclosure resembles that of multipacks for bottles or cans. The rack may also be configured for holding the containers in a hanging fashion. The containers in such multipacks are typically such intended for single use containers, e.g. of the kind disclosed herein. The multipack of this disclosure may also comprise a coupling device. 
         [0033]    Another aspect of this disclosure is a method for the manufacture of a container that holds pressurized gas. The method is described with a certain sequence of steps, but it should be understood that while the sequence of steps may be carried out as described, certain steps may also be carried out in a different sequence or some steps may be carried out partially or fully in parallel. For example, described below is fitting of a plug device at the leading end of a plunger, which may be carried out before, simultaneously or after association of the container blank with the seat. 
         [0034]    The method comprises providing a container blank, introducing pressurized gas through the open end of the neck portion, introducing a plug device into the neck and tightly affixing the plug within the neck. The container blank is of the kind configured to hold the pressurized gas and having a container body with an integral neck, the neck having an open end portion and at least said end portion being formable under defined conditions. After pressurized gas is introduced into the container, the plug device, which is of the kind specified above, is introduced into the open end while maintaining gas pressure. Once the plug device is inserted into the open neck, it is tightly affixed within the neck by applying said condition to thereby form the upper end to tightly engage the plug device&#39;s external faces. Such conditions may be a forced compression applied on the end portion of the neck about said device. Where the gas is carbon dioxide, a single use canister for the preparation of carbonated drink is, thus, obtained. 
         [0035]    By one embodiment, the method comprises associating the container blank with a block in a gas tight manner, such that (i) the open end portion of the container&#39;s neck protrudes through an opening in the block into a working space that is linked to a source of pressurized gas, and that (ii) leakage of gas out of the opening is hindered; then permitting gas to flow from a gas source into the container via said working space; while maintaining gas pressure, inserting and tightly fixing the plug device in the open end of the neck. The tight fixing may be achieved through crimping the end portion of the neck about the plug device to thereby form tight engagement between the neck and side surfaces of the plug device. 
         [0036]    Insertion of the plug typically comprises fitting the plug device at a leading end of a plunger, that can axially reciprocate along an axis defined by the neck, between a first plunger position and a second plunger position that is more proximal to said open end. After such fitting, the plunger is axially displaced into the second plunger position to thereby introduce the plug device into the neck&#39;s open end. 
         [0037]    By another embodiment of the method, the plunger axially reciprocates within an axial bore that is formed in a piston. The piston can also axially reciprocate along the same axis between a first piston position and a second piston position that is more proximal to the neck&#39;s open end. In accordance with this embodiment, the tight affixing of the plug device within the neck is carried out while maintaining the plunger in the second plunger position and axially displacing the piston to its second piston position, in which it applies a crimping-biasing force on the neck&#39;s upper end to thereby crimp it about the plug device. The piston may comprise a depression formed in the piston&#39;s face that faces the neck, in a mid-portion thereof that surrounds said bore (in which the plunger reciprocates). In the second piston position, the depression bears on the upper end of the neck and the overall concave shape of the depression then guides an inward crimping of the necks upper end about the plug device. The depression is typically circular in its perimeter and its dimension corresponds to that of the neck&#39;s upper end. 
         [0038]    As will be appreciated, depending on the intended manner of securing the plug within the opening of the container&#39;s neck, additional or alternative steps for such securing may be added, such as rotational insertion of the plug in the case of screw-fitting or a welding step in one of a variety of welding techniques known per se. 
         [0039]    Also provided by this disclosure is an apparatus for producing a container of the kind specified herein. The apparatus comprises a block, a pressurized gas conduit and a piston with a plunger. The block defines a working space with axially extending side walls and a base. The pressurized gas conduit leads into said working space and is linked to a pressurized gas source. The piston is received within said working space, forming a gas-tight association with the side walls and is capable of axial reciprocation within the working space between the first piston position and the second piston position more proximal to the said base. An axial bore is formed in said piston and accommodates a plunger. The plunger forms a gas-tight association with the bore&#39;s walls and the association is such to permit axial reciprocation of the plunger within the bore, between said first plunger position and said second plunger position which is proximal to said base. The base has an opening that is formed at the end of a seat configured for receiving an upper portion of the container blank, and for forming a gas-tight association therewith; with the upper, open end of the neck protruding through the opening into said working space. The plunger has a leading end and is configured for holding a plug device of the kind specified herein and for introducing the plug device into the upper end of the neck when in the second plunger position. The piston is adapted for applying a crimping-biasing force on the upper end of the neck to thereby crimp said upper end about external faces of said plug device. The piston may have a depression to serve this purpose, of the kind specified above. 
         [0040]    The apparatus that may be configured to operate in an operational mode that comprises: associating the upper end of the container with the seat; introducing pressurized gas into the container via the working space; axially displacing the plunger fitted with said plug device into the second plunger position to thereby introduce the device into said open end; and, while maintaining the plunger in said second plunger position, axially displacing the piston to the second piston position in which it applies a crimping-biasing force on the neck&#39;s upper end, to thereby crimp it. 
         [0041]    The apparatus may be modified, in an analogous manner to that described above in reference to the process, to accommodate additional or alternative means for securing the plug with the container&#39;s neck. 
         [0042]    Also provided by this disclosure is a container blank with a body and neck integral therewith having an open end; the body is configured for holding pressurized gas; the neck is adapted to receive a plug device of the kind specified. The open end may be formable under defined conditions, e.g. by pressure forming. The container blank is usually made entirely of the same material, which may be metal, e.g. aluminum. 
         [0043]    This disclosure provides, by another of its aspects, a coupling element for coupling a gas container, particularly of the kind disclosed herein, to an appliance or system in a manner so as to permit gas supply from the container to a gas conduit of an appliance or system; for example, carbon dioxide appliance or system for the preparation of the carbonated drink. The element comprises a gas channeling member that has an elongated shaft extending axially from a base thereof to a shaft end. The shaft is configured for fitting into a bore of the plug opening in the container and further configured so that, once coupled with the container, it causes irreversible opening of a barrier element that is formed at the inner end of said bore. The shaft has openings at, or proximal to, the shaft end leading into said conduit. The coupling element of this aspect may, by one embodiment, be an element that is formed as a part of said appliance or system. By another embodiment, such an element is an independent coupling device for coupling the container to a gas port of an appliance or system. 
         [0044]    By an embodiment of the latter aspect, the coupling element also defines one or more gas-release channels, configured to form, during decoupling of the container and the coupling element, a gas-release conduit between the container&#39;s interior and the exterior. The purpose of such gas-release conduit is to enable slow or controlled release of gas from the container&#39;s interior, in the event that gas pressure remains within the container prior to such decoupling. This may be a stand-alone controlled release feature or one that functions in conjunction with a mechanism that is an integral part of the container, as described above. This, as noted above, is intended to avoid a violent or abrupt release of pressure upon decoupling. 
         [0045]    The gas-release conduit may, by one embodiment, be constituted by one or more axial grooves or recesses formed on the shaft&#39;s face that faces the bore&#39;s internal wall. In this latter embodiment, the conduit is defined between the shaft and the bore&#39;s internal walls. 
         [0046]    Provided by another aspect of this disclosure is a coupling device for coupling a pressurized gas container to a pressurized gas port of an appliance or system. The device is configured for coupling to the container&#39;s opening, at its first end, and for coupling to a fitting fitment of a gas port of the appliance or system, at its second end. The term “coupling” used herein in connection with the device is intended to denote that the two coupled elements are functionally linked 
         [0047]    Defined within said coupling device is a gas conduit that once the device is so coupled establishes a gas-flow channel from the container&#39;s opening to the gas port of said appliance or system. Said first end comprises a gas channeling member that has an elongated shaft that extends from a base to a shaft end. The shaft is configured (e.g. in terms of position and dimension) to penetrate the bore of the plug that is disposed in the opening of the container during coupling of the container to said one end to thereby cause an irreversible opening of the barrier element formed at the inner end of said bore. The shaft has openings at or proximal to the shaft end leading into said gas transfer channel, e.g. leading into a lumen formed within the shaft that is linked to said channel. 
         [0048]    By one embodiment the coupling device comprises a cup-shaped connector portion at its first end, the connector having an end wall and side walls extending therefrom and being configured for coupling with a neck portion of the pressurized gas container. According to this embodiment the gas channeling member extends within the cup-shaped connector from a base in said end wall. The internal side walls of the connector are, typically screw-threaded and the coupling is then through a screw-type engagement with an external threading on said neck portion. Said cup-shaped connector portion has a ring at its end fitted to the connector portion in a screw-type engagement and serving for fastening the device to said neck portion after coupling. 
         [0049]    The coupling device may comprise an outlet valve at the second end configured for sealing the gas outlet of said gas conduit at said second end and for opening upon coupling of said second end to the appliance or system to permit gas egress into the gas-ducting system of said appliance or system. The device may also comprise a safety plug adapted to discharge gas when the pressure within gas transfer channel exceeds a predetermined level. 
         [0050]    Once the coupling device is coupled to the pressurized gas container, at its first end, the barrier is opened or ruptured, whereupon gas is free to flow out of the container; the sealing arrangement described above ensures that no gas would leak to the surrounding environment. However, should the device be accidentally decoupled from the container, there is a risk of an abrupt pressurized gas egress from the container to the external environment which, under some circumstances, may be hazardous. Thus, in order to avoid such abrupt gas release, by an embodiment of this disclosure, a safety feature is provided to block unintended decoupling of the coupling device from the pressurized gas container, as long as pressure within the container exceeds the predetermined level, e.g. a level defined by safety standards as being safe. The safety feature includes a safety arrangement which is configured for locking the coupling device onto the container&#39;s neck, as long as the gas pressure within the container exceeds said predetermined pressure level. This may be achieved, by an embodiment of this disclosure, by a safety bolt that is configured to lock the coupling device in a coupled state as long as the pressure within the container exceeds said predetermined pressure level. By way of example, such bolt may be maintained in a locked state by a pin that engages with the safety bolt and that is kept in such an engaging state by the gas pressure; and once the gas pressure reduces to a level below said predetermined level, the pin can disengage the bolt, which is thereby released to permit decoupling of the device from the container. 
         [0051]    The term “bolt” should be understood to encompass any functional element that can induce such locking. 
         [0052]    A coupling device according to an embodiment of this disclosure with a safety arrangement comprises a safety locking element, e.g. a safety bolt configured for fitting into a recess or groove formed in the container&#39;s neck to block accidental decoupling of the device from the container. The safety bolt may be configured for displacement, e.g. linearly, between a first, locking bolt position in which it fits into said recess (and thereby blocks decoupling) and a second, releasing bolt position in which it is removed from said recess. The arrangement is typically such that the safety bolt is biased into the second bolt position by an associated urging element and locked in the first position by an associated locking arrangement adapted to (i) lock the bolt in the first bolt position as long as decoupling of the coupling device from the container is to be avoided (namely as long as the gas pressure within the container exceeds said predetermined level), and (ii) release the bolt once the pressure in the container is reduced to a safe pressure level, namely below said predetermined level. Locking of the safety bolt in said locking position and releasing it once the pressure in the container is reduced to a safe level may be achieved by a variety of means. 
         [0053]    By one embodiment the locking arrangement comprises a locking pin that can reciprocate between a locking state in which it engages the safety bolt and locks it in the first bolt position, and a releasing state in which the pin is disengaged from the bolt which can, thus, be displaced into the second bolt position. The locking pin is typically biased into the releasing state by an associated urging element, e.g. a spring, and is forced into the locking state (against this biasing force of the urging element) by the gas pressure within the container, as long as the gas pressure exceeds said predetermined pressure level. The locking pin may, for example, reciprocate in a pin bore that is in gas communication with the gas conduit and is, thus, pushed by the gas pressure, against the biasing force of its associated urging elements. For this, the locking pin can have shoulders that form a gas-tight seal with the pin bore&#39;s wall such that gas pressure acting on said shoulders forces the pin into the locking state. The pin-associated element imparts an urging force on the locking pin such that it will exceed the force applied by the gas pressure when the pressure level is reduced below said predetermined pressure level to thereby cause its displacement to the releasing states. 
         [0054]    The safety bolt may be forced into the first bolt state as part of the coupling action. For example, the device may comprise a locking ring that can rotatably reciprocate between a locking state in which it causes the safety bolt to displace into the first bolt position and an unlocking state in which it permits displacement of the safety bolt into the second bolt position. The arrangement is typically such the locking ring&#39;s rotation occurs as part of the coupling action. For example, the ring may be associated with a biasing element that urges it into the locking state and upon coupling it rotates to its locking state thus forcing the bolt into the recess or groove in the container&#39;s neck. The piercing of the barrier element permits the pressurized gas to enterer the gas conduit within the coupling device thereby locking the bolt in the first, safety bolt position. 
         [0055]    Further provided by this disclosure is an appliance adapted for preparing or dispensing carbonated drink. Such appliance or system may be intended only for the preparation of carbonated drinks or intended for the preparation of carbonated as well as other drinks. The appliance or system comprises a coupling element for coupling with a carbon dioxide containing canister and for receiving the pressurized carbon dioxide therefrom. The coupling element comprises a coupling element for coupling with the end portion of the neck and comprises a gas-channeling member with a spiked end. The canister is of the kind specified above and upon coupling of the neck with the coupling element the gas-channeling member ruptures the barrier element to permit channeling of carbon dioxide from the container to the appliance, while the sealing member maintains gas-tight association with said member to avoid gas leakage. 
       Embodiments 
       [0056]    The present disclosure also encompasses embodiment as defined in the following numbered phrases. It should be noted that these numbered embodiments intended to add to this disclosure and is not intended in any way to be limiting. Note also that although the term “embodiment” is used in a singular form also where a phrase references a previous phrase that in fact relates to many embodiments (for example phrase No. 47 that refers back to phrase No. 46, where the latter relates to several embodiments), such a numbered phrase (e.g. No. 47) is intended to encompass all the embodiments that are encompassed by the embodiment to which it refers, with the added element of defined in a such a referencing numbered phrase.
   1. A pressurized gas container for association with and supplying gas to a pressurized gas port of an appliance or system, the container comprising:   
 
         [0058]    a container body, defining a pressurized gas enclosure, and a neck integral therewith defining a gas outlet; 
         [0059]    the neck
       having an end portion that is configured for coupling with a coupling element, which may be a coupling element integral with or forming part of said gas port or may be a coupling element of a coupling device or adapter configured for coupling with said port, and being   fitted with a plug;       
 
         [0062]    the plug having
       a barrier element sealing said enclosure and configured for non-reversible rupturing by a shaft of a gas-channeling member of said coupling element, and having   one or more sealing elements, distinct from said barrier element and configured for forming a gas-tight association with said shaft.       2. The container of embodiment 1, wherein   
 
         [0066]    the pressurized gas within the container is pressurized carbon dioxide, and is intended for association with a carbonated drink dispensing appliance or system in which the pressurized carbon dioxide is utilized for the preparation of the carbonated drink.
   3. The container of embodiment 2, wherein the container is configured for association with said appliance or system such that the pressurized carbon dioxide for the preparation of the carbonated drink is drawn when needed out of the container.   4. A pressurized gas container for association with and supplying gas into a pressurized gas port of the appliance or system, the container comprising:   
 
         [0069]    a container body, defining a pressurized gas enclosure and a neck integral therewith defining a gas outlet; 
         [0070]    the neck
       having an end portion that is configured for coupling with a coupling element of the kind defined in embodiment 1 and is fitted with a plug;       
 
         [0072]    the plug being formed with a bore that is fitted with a barrier element (within or at end of the bore) that forms a gas impermeable barrier that seals said enclosure, 
         [0073]    said barrier element being rupturable or pierceable by a shaft of a gas-channeling member of said coupling element, and 
         [0074]    said bore being configured with at least one sealing element for forming a gas-tight association with said shaft.
   5. The container of any one of embodiments 1-4, wherein the gas is carbon dioxide and the appliance or system is adapted for the preparation of a carbonated drink.   6. The container of any one of the preceding embodiments, wherein said barrier element is a pierceable metal sheet.   7. The container of embodiment 4, wherein said sheet is configured for rupturing in the event that the pressure within the container exceeds a predefined threshold.   8. The container of any one of the preceding embodiments, wherein said plug is fitted into the container&#39;s neck such that said bore is substantially co-axial with said neck.   9. The container of any one of the preceding embodiments, wherein said plug defines an axis extending between an exterior end and an interior end (e.g. having an overall cylindrical shape) and being formed with a generally axial bore extending between the two ends.   10. The container of embodiment 9, wherein said barrier is formed at said interior end of the bore and said one or more sealing elements are formed within said bore at said exterior end or in between said interior and said exterior end.   11. The container of embodiment 10, wherein the one or more sealing elements are one or more O-rings.   12. The container of embodiment 11, wherein said O-ring is fitted within a circumferential groove formed in the walls of said bore.   13. The container of embodiment 8, wherein the plug is formed with an uneven external surface.   14. The container of any one of the preceding embodiments, wherein said plug is fitted within said neck.   15. The container of embodiment 14, wherein the plug is pressure fitted within said neck.   16. The container of any one of the preceding embodiments, wherein said body has an average wall thickness that is less than 60%, 55%, 50%, 45% or even less that 40% of the average wall thickness of a container of similar dimensions an made of similar material that is intended for multiple use.   17. The container of any one of the preceding embodiments, comprising a flow-restricting element configured to permit (i) free flow of pressurized gas as long as the neck is coupled to the coupling element and (ii) gradual outflow of gas upon decoupling of the coupling element from the neck.   18. The container of embodiment 17, wherein the flow-restricting element comprises a floating member displaceable between a seated position in which it bears against a seat at an outlet of the container to thereby partially seal the container&#39;s outlet and an unseated position in which it is distanced from said seat and permitting free gas outflow through said outlet, said floating member being biased, e.g. by gas outflow or by an associated biasing element (such as a spring), into said seated position and being configured for displacement into said unseated position by the shaft of said gas channeling member.   19. The container of embodiment 18, wherein said floating member is rounded, e.g. spherical.   20. The container of embodiment 18 or 19, wherein said flow-restricting element is situated in a position interior to said barrier element.   21. The container of embodiment 20, wherein said flow-restricting element comprises a nesting member fitted within the container&#39;s neck and having an upper segment defining said seat and a lower segment comprising arms configured to limit displacement of said floating member.   22. The container of embodiment 21, wherein the seat defines flow channels.   23. The container of embodiment 21, wherein flow channels are defined between the seat and the neck&#39;s interior face.   24. A multipack comprising   
 
         [0095]    a holder rack; 
         [0096]    a carrying element; and 
         [0097]    a plurality of pressurized gas containers, e.g. a plurality of pressurized carbon dioxide-containing canisters.
   25. The multipack of embodiment 24, wherein the rack is configured as a case, a box or multipack rings.   26. The multipack of embodiment 25, wherein said holding rack is integral with the carrying element.   27. The multipack of any one of embodiments 24-26, wherein the containers are intended for single use.   28. The multipack of any one of embodiments 24-27, wherein the containers are those defined in any one of embodiments 1-23.   29. A plug device for integration in a container of any one of embodiments 1-23.   30. A plug device for integration into a neck of a pressurized gas container blank, the plug comprising   
 
         [0104]    a bore extending through the plug; 
         [0105]    a barrier element fitted in the bore (at an end of or within said bore) and configured for non-reversible rupturing by a shaft of a gas-channeling member of an adapter of an appliance or system; and 
         [0106]    one or more sealing elements within said bore, distinct from said barrier element and configured for forming a gas-tight association with said shaft.
   31. The plug device of embodiment 30, being formed with a bore that is fitted with a barrier element that once the device is integrated into said neck forms a gas impermeable barrier sealing said bore from a pressurized gas enclosure within said container.   32. The plug device of embodiment 30 or 31, wherein said barrier element is a pierceable metal sheet.   33. The plug device of embodiment 32, wherein said barrier element is configured for rupturing in the event that the pressure differential between its internal face that in use faces the container&#39;s pressurized gas enclosure and its external face exceeds a predefined threshold.   34. The plug device of any one of embodiments 30-33, wherein said plug is configured for fitting into the container&#39;s neck such said bore is substantially co-axial with said neck.   35. The plug device of any one of embodiments 30-34, having an overall cylindrical shape with an exterior end and an interior end and an axial bore extending therebetween.   36. The plug device of embodiment 35, wherein said barrier is formed at said interior end and said one or more sealing elements are formed within said bore at said exterior end or in between said interior and said exterior end.   37. The plug device of embodiment 36, wherein the one or more sealing elements are one or more O-rings.   38. The plug device of embodiment 37, wherein said O-ring is fitted within a circumferential groove formed in the walls of said bore.   39. The plug device of embodiment 38, wherein the plug is formed with an uneven (non-uniform) external surface.   40. The plug of any one of embodiments 30-39, for fitting within said neck.   41. The plug device of embodiment 40, wherein the plug is configured for pressure fitting within said neck.   
 
         [0118]    In the following methods defined in the independent statements or in dependent ones, the sequence of steps may be as specified or may be a different sequence. Also, some of the specified method steps may also fully or partially overlap other steps, i.e. may be carried out fully or partially in parallel to one another.
   42. A method for the manufacture of a container with a pressurized gas, comprising:   
 
         [0120]    (a) providing a container blank configured to hold pressurized gas, the container blank having a container body, defining a pressurized gas enclosure, and a neck at its upper end, the neck having an upper, open end portion, at least said upper end portion being formable under defined conditions; 
         [0121]    (b) introducing pressurized gas into said enclosure through said open end; 
         [0122]    (c) while maintaining gas pressure, introducing a plug device into said open end, the plug device comprising external side walls and a bore formed within it, the bore being fitted with a barrier element configured for non-reversible rupturing by a shaft of a gas-channeling member of coupling element of a device or system, and comprising one or more sealing elements within said bore distinct from said barrier element and configured for forming a gas-tight association with said member; and 
         [0123]    (d) tightly affixing said plug device within said neck by forming said upper end to tightly engage the plug device&#39;s external faces.
   43. The method of embodiment 42, wherein said upper end of the neck is made of metal and said forming is a pressure-forming.   44. The method of embodiment 42 or 43, wherein the container blank is made entirely of the same material.   45. The method of embodiment 44, wherein the container is made of metal, e.g. aluminum.   46. The method of any one of embodiments 42-45, wherein the gas is carbon dioxide.   47. The method of embodiment 46, for the manufacture of a pressurized gas canister for association with an appliance or system adapted for the preparation of a carbonated drink.   48. The method of any one of embodiments 45-47, comprising:   
 
         [0130]    (m) associating the container blank with a block in a gas tight manner such that (i) the open end of the container&#39;s neck protrudes through an opening in the block into a working space that is linked to a source of pressurized gas, and that (ii) leakage of gas out of the opening is hindered; 
         [0131]    (n) permitting flow of gas from the gas source into the container via said working space; 
         [0132]    (o) while maintaining gas pressure, inserting said plug device into said open end; and 
         [0133]    (p) tightly affixing said plug device within said neck, e.g. by crimping said upper end to tightly engage said side surfaces.
   49. The method of embodiment 48, wherein step (o) comprises:   
 
         [0135]    (o1) fitting said plug device at a leading end of a plunger that can axially reciprocate along an axis defined by said neck between a first plunger position and a second plunger position that is more proximal to said open end, and 
         [0136]    (o2) axially displacing said plunger into the second plunger position to thereby insert the plug device into said neck.
   50. The method of embodiment 49, wherein:   
 
         [0138]    said plunger axially reciprocates within an axial bore formed in a piston; 
         [0139]    the piston can axially reciprocate along said axis between a first piston position and a second piston position that is more proximal to said open end; and wherein step (p) comprises 
         [0140]    while maintaining the plunger is said second plunger position, axially displacing said piston to said second piston position in which it applies a crimping-biasing force on said upper end to thereby crimp said upper end.
   51. The method of embodiment 50, wherein   
 
         [0142]    the piston comprises a depression in the piston&#39;s face that faces said neck in a mid-portion thereof that surrounds said bore; and wherein 
         [0143]    in said second piston position the depression bears on said upper end of the neck and such bearing applies said crimping-biasing force.
   52. The method of embodiment 51, wherein   
 
         [0145]    said depression is circular and its perimeter is dimensioned to correspond to that of said upper end.
   53. An apparatus for producing a container having a container body and a neck integral therewith that is fitted with a plug, the apparatus comprising:   
 
         [0147]    a block defining a working space with axially extending side walls and with a base; 
         [0148]    a pressurized gas conduit leading into said working space and linked to a pressurized gas source; 
         [0149]    a piston, received in said working space and forming a gas-tight association with said side walls, the piston being capable of axial reciprocation within the working space between a first piston position and a second piston position that is more proximal to said base; 
         [0150]    an axial bore formed in said piston and a plunger that is accommodated in said bore, forms a gas-tight association with bore&#39;s walls and that can axially reciprocate within said bore between a first plunger position and a second plunger position that is more proximal to said base; 
         [0151]    the base having an opening formed at the end of a seat, the seat being configured for receiving an upper end of a container blank and for forming a gas-tight association therewith, with the upper end of the neck protruding through the opening into said working space; 
         [0152]    the plunger having a leading end configured for holding a plug device as defined in any one of embodiments 29-41 and for introducing the plug device into the upper end of the neck when in the second plunger position; 
         [0153]    the piston being adapted for applying a crimping-biasing force on said upper end to thereby crimp said upper end on external faces of said plug device.
   54. The apparatus of embodiment 53, wherein   
 
         [0155]    the piston comprises a depression formed in the piston&#39;s face that faces said neck in a mid-portion thereof that surrounds said bore; and wherein 
         [0156]    in said second piston position the depression bears on said upper end of the neck and such bearing applies said crimping-biasing force.
   55. The apparatus of embodiment 53 or 54, configured for operating in an operational sequence that comprises   
 
         [0158]    (a) associating the upper end of the container with the seat; 
         [0159]    (b) introducing pressurized gas into the container via said working space; 
         [0160]    (c) axially displacing the plunger fitted with said plug device into the second plunger position to thereby introduce the device into said open end; and 
         [0161]    (d) while maintaining the plunger is said second plunger position, axially displacing said piston to said second piston position in which it applies a crimping-biasing force on said upper end to thereby crimp said upper end.
   56. A container blank with a body and a neck integral therewith and having an upper, open end, wherein   
 
         [0163]    the body is configured for holding pressurized gas; 
         [0164]    the neck is adapted to receive a plug device as defined in any one of embodiments 29-41; and 
         [0165]    said upper end being formable under defined conditions.
   57. The container blank of embodiment 56, wherein said upper end is formable by pressure forming.   58. The container blank of embodiment 56 or 57, made of metal, e.g. of aluminum.   59. The container blank of any one of embodiments 56-58, for use in the production of a container of any one of embodiments 1-23.   60. A coupling element for coupling a pressurized gas container to an appliance or system to permit gas supply to a gas conduit system of the appliance or system, the element comprising a gas channeling member having an elongated shaft that extends axially from a base to a shaft end, the shaft being configured for fitting into a bore of a plug in the opening of the container and, once coupled with the container, causes irreversible opening of a barrier element formed at an inner end of said bore; the shaft having openings at or proximal to the shaft end leading into said gas conduit.   61. The element of embodiment 60, defining also one or more gas release channels that are configured to form a gas-release conduit between the container&#39;s interior and the exterior during decoupling of the container and the coupling element.   62. The element of embodiment 61, wherein such gas-release conduit being constituted by one or more axial grooves or recesses at the shaft&#39;s peripheral face that faces the bore&#39;s internal walls.   63. The element of any one of embodiments 60-62, being an element of said appliance or system.   64. The element of any one of embodiments 60-62, being an independent device for coupling the container to a gas port of the appliance or system.   65. The device of embodiment 64, for coupling a pressurized gas container to a gas port of an appliance or system, wherein:   
 
         [0175]    the device is configured for coupling to the container&#39;s opening, at its first end, and for coupling to a gas port of appliance or system, at its other end, and defined within it is a gas conduit that once so coupled channels gas from the container&#39;s opening to the gas port of said appliance or system; 
         [0176]    said first end comprises a gas channeling member having an elongated shaft that extends from a base to a shaft end, the shaft being configured for fitting into a bore of a plug in the opening of the container and, once coupled with the container, causes irreversible opening of a barrier element formed at an inner end of said bore; and 
         [0177]    the shaft having openings at or proximal to the shaft end leading into said gas conduit.
   66. The device of embodiment 65, wherein   
 
         [0179]    said first end comprises a cup-shaped connector portion with an end wall and side walls that is configured for coupling with a neck portion of the pressurized gas container; and 
         [0180]    said gas channeling member extends from a base in said end wall within the cup-shaped connector portion.
   67. The device of embodiment 66, wherein said side walls are internally screw-threaded and the coupling is through a screw-type engagement with an external threading on said neck portion.   68. The device of any one of embodiments 65-67, wherein said second end comprises a valve configured for sealing the gas outlet at said second end and for opening upon coupling of said second end to the appliance or system to permit gas egress into the gas port of said appliance or system.   69. The device of any one of embodiments 65-68, wherein said second end is externally screw-threaded for coupling to a matching fitment in said appliance or system.   70. The device of any one of embodiments 65-69, wherein said cup-shaped connector portion has a ring at its first end fitted to the connector portion in a screw-type engagement and serving for fastening the device to said neck portion after coupling.   71. The device of any one of embodiments 65-70, comprising a safety plug adapted to discharge gas when the pressure within gas transfer channel exceeds a predetermined level.   72. The device of any one of embodiments 65-72, comprising a safety arrangement configured for locking the device onto the container&#39;s neck as long as the gas pressure within the container exceeds a predetermined pressure.   73. A device for coupling a pressurized gas container to a gas port of an appliance or system, comprising:   
 
         [0188]    a body having a cup-shaped connector with and end wall and side walls at its first end that is configured for coupling to a neck of the gas container&#39;s, and having a fitting arrangement at its second end for coupling to a fitment of a gas port of an appliance or system; 
         [0189]    a gas channeling member having an elongated shaft with a lumen and extending from a base in said end wall to a shaft end, the shaft end having openings into said lumen; the shaft being configured for fitting into a bore of a plug in the opening of the container and, once coupled with the container, causes irreversible opening of a barrier element formed at an inner end of said bore; 
         [0190]    a gas conduit formed within said body and linking said lumen with a gas outlet at said second end; 
         [0191]    an outlet valve for sealing said gas outlet and for opening the outlet upon coupling of said second end to the appliance or system to permit gas egress into said gas port; and 
         [0192]    a safety bolt configured for fitting into a recess or groove formed in the container&#39;s neck to block accidental decoupling of the device from the container.
   74. The device of embodiment 73, wherein   
 
         [0194]    said safety bolt can be displaced between a first bolt position in which it engages, e.g. fits into said recess or groove, and a second bolt position in which it is removed from said recess.
   75. The device of embodiment 74, wherein   
 
         [0196]    the safety bolt is biased into said second bolt position, e.g. by an associated urging element.
   76. The device of embodiment 75, wherein   
 
         [0198]    the safety bolt is locked in the first bolt position by an associated locking arrangement that is adapted to (i) lock the bolt in said first position as long as the gas pressure within said container exceeds a predetermined pressure, and (ii) release the bolt once the pressure in the container is reduced to a pressure level that is below said predetermined level.
   77. The device of embodiment 76, wherein the locking arrangement comprises a locking pin that   
 
         [0200]    can reciprocate between a locking state in which it engages the bolt and locks it in the first bolt position and a releasing state in which pin disengages the bolt to permit it to be displaced into the second bolt position; 
         [0201]    is biased into the releasing state by an urging element; and 
         [0202]    is forced into the locking state against the biasing force of the urging element by the gas pressure within the container as long as said pressure exceeds a predetermined pressure.
   78. The device of embodiment 77, wherein the pin   
 
         [0204]    reciprocates in a pin bore that is in gas communication with the gas conduit, and 
         [0205]    the pin has shoulders that form a gas-tight seal with the pin bore&#39;s wall such that gas pressure on said shoulders forces the pin into the blocking state.
   79. The device of embodiment 78, wherein a head space above said shoulders is in gas communication with said gas conduit.   80. The device of any one of embodiments 73-79, comprising a locking ring that can rotatably reciprocate between a locking state in which it forces the bolt into the first bolt position and an unlocking state in which it permits displacement of the bolt into the second bolt position.   81. The device of embodiment 76, wherein the ring is associated with by a biasing element that urges it into its locking state.   82. The device of any one of embodiments 64-81 for associating with the carbon dioxide container of any one of embodiments 1-23 or a container fitted with a plug device of any one of embodiments 29-41.   82. An appliance adapted for preparing or dispensing carbonated drink, the appliance comprising an adapter for associating with a pressurized carbon dioxide-containing canister and for receiving the pressurized carbon dioxide therefrom; wherein   
 
         [0211]    said adapter comprises a coupling element and a gas channeling member having an elongated shaft that extends from a base to a shaft end, the shaft being configured for fitting into a bore of a plug in the opening of the canister and, once coupled with the canister, causes irreversible opening of a barrier element formed at an inner end of said bore; 
         [0212]    the canister comprises a canister body and a neck integral therewith at its upper end fitted with the plug, the plug having a barrier element configured for non-reversible rupturing by said gas-channeling member and having one or more sealing elements, distinct from said barrier element, and configured for forming a gas-tight association with said member; and wherein 
         [0213]    upon coupling of said neck with said adapter said gas-channeling member ruptures said barrier element to permit channeling of pressurized carbon dioxide from the container to the appliance while the sealing member maintains a gas-tight association with said member to avoid gas leakage.
   83. The device of embodiment 82 for associating with a carbon dioxide container according to any one of embodiments 1-23 or a container fitted with a plug device of any one of embodiments 29-41.   
 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0215]    In order to better understand the subject matter that is disclosed herein and to exemplify how it may be carried out in practice, embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which: 
           [0216]      FIG. 1  shows a schematic cross-section representation through a canister of the invention, typically one that contains pressurized carbon dioxide. 
           [0217]      FIG. 2  is an enlarged schematic cross-section representation of the upper portion including the neck of the canister. 
           [0218]      FIGS. 3A-3F  are schematic cross-sectional representations of some operational parts of the apparatus used for the manufacture of a canister of the kind shown in  FIGS. 1 and 2  in several successive manufacturing sequences. 
           [0219]      FIGS. 4A-4C  are schematic cross-sectional representations through the upper portion of a canister and a coupling element that is part of an appliance or system, e.g. such used for preparation of a carbonated drink, illustrating several successive sequences of coupling of the canister with the coupling element. 
           [0220]      FIGS. 5A-9B  are schematic representations of some embodiments of plugs that may be fitted into a cavity within the neck portion of a canister blank to form a canister of this disclosure.  FIGS. 5A ,  5 C,  6 A,  7 A and  8 A show an exploded view of the upper portion of the canister blank and the plug; while  FIGS. 5B ,  6 B,  7 B and  8 B are respective longitudinal cross-sectional views of the upper portion of the canister with the plug fitted within the cavity in the neck portion.  FIG. 9A  is an exploded view of a plug in isolation and  FIG. 9B  is a longitudinal section of such a plug. 
           [0221]      FIG. 10A  is a longitudinal cross-section through (i) the neck of a canister that comprises a flow-restricting element in accordance with an embodiment of this disclosure and (ii) through a gas-channeling member of an appliance or system (the appliance or system, not shown), the canister and said member being separated from one another prior to coupling. 
           [0222]      FIG. 10B  shows the canister of  FIG. 10A  and the gas-channeling member coupled to one another. 
           [0223]      FIG. 10C  is a side view of the nesting member of the flow-restricting element. 
           [0224]      FIG. 10D  is a cross-section through lines C-C in  FIG. 10C . 
           [0225]      FIGS. 11A and 11B  are, respectively, schematic exploded view and a cross-sectional view of a coupling device for coupling a pressurized gas canister to an appliance or system. 
           [0226]      FIGS. 12A and 12B  are, respectively, schematic perspective view and longitudinal cross-sectional view of the coupling device of  FIGS. 11A and 11B  coupled to a canister. 
           [0227]      FIG. 13  is an exploded view of a coupling device according to another embodiment incorporating a safety arrangement against premature decoupling of the device from the pressurized gas canister. 
           [0228]      FIGS. 14A and 14B  are, respectively, longitudinal cross-sections along respective planes A-A and B-B, marked in  FIG. 13 . 
           [0229]      FIGS. 15A and 15B  are side elevation and longitudinal cross-section, respectively, of a pressurized gas canister coupled with a the coupling device of  FIGS. 13-14B . 
           [0230]      FIGS. 16A-16C  are longitudinal cross-sections through the canister&#39;s neck and a coupling element with a shaft with defined gas-release conduits in a state of coupling ( FIG. 16A ), during decoupling ( FIG. 16B ) and being totally decoupled ( FIG. 16C ). 
           [0231]      FIGS. 17A and 17B  show two examples of multipacks (6-pack in this example) of canisters of the kind described herein. 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0232]    In the following, the present disclosure will be elaborated and illustrated through description of some specific embodiments with reference to the annexed drawings. The illustrated embodiments refer to a canister, such as that containing carbon dioxide for use in an appliance or system for preparation of a carbonated drink. It is to be understood that the figures are intended to exemplify the general principles of this disclosure and are not to be construed in any way to be limiting. 
         [0233]    The description of canister below makes occasional reference to a top or bottom. This is done for convenience of description only. As can be appreciated in use the orientation has no functional significance and it may be coupled to the appliance or system in any desired orientation according to various engineering or other considerations. 
         [0234]    Referring first to  FIG. 1 , shown is a canister  100  having a body  102 , defining a pressurized gas enclosure  103 , and having an integral neck  104  with an external threading  106  for coupling to a coupling element of an appliance or system adapted, in this specific example, for the preparation of a carbonated drink. It should be noted that coupling by threading is only one example and other types of coupling are possible, such as for example snap-fitting. The canister may be made from a variety of different materials, a typical example being metal, such as aluminum. Fitted at the canister&#39;s bottom end is a base element  108 , typically made of plastic serving as a base on which the canister may stand. Included within the neck is a plug  110 . 
         [0235]    The upper portion of the canister including neck  104  is shown in  FIG. 2 . Particularly, what can be seen in more detail is plug  110  that is fitted at the upper part of the neck and is tightly secured in position by crimping of the upper portion  112  and particularly the upper lips  114 , e.g. in a manner as will be described below. As can be seen, the plug device  110  has an external uneven surface  116  that provides for tighter engagement with the surrounding parts of the neck. As can also be seen, the bore within the upper end portion of the neck is of a larger diameter, defining a shoulder  118  that seats the bottom end  120  of the device. 
         [0236]    The device  110  includes a bore  122  which is coaxial with bore  124  within neck  104 . Formed at the bottom end of plug  110  is a barrier element  126  which is constituted by a metal sheet that seals enclosure  103 . The plug also includes a sealing member which is constituted by an O-ring  128  that is accommodated within a circumferential groove  130  formed within the internal walls of bore  122 . 
         [0237]    Reference is now being made to  FIGS. 3A-3F  showing sequences in the filling and manufacture of a canister of the kind described in  FIGS. 1 and 2 . The structural elements that eventually form the canister are the canister blank  132  and a plug device  110 , the latter shown here fitted on the leading end of plunger  170 , the function of which will be explained further below. 
         [0238]    Further illustrated in these figures are the functional components of the apparatus for carrying out the method for said filling and manufacturing (which are annotated, particularly, in  FIG. 3A ). It includes the main block  140  that defines a working space  142 , having axially orientated side walls  144  and an end wall  146 . The end wall  146  has an opening  148  which is at the end of seat  150  that has a shape matching the upper portion of the canister blank  132 . 
         [0239]    The seat has circumferential grooves that accommodate O-rings  152 ,  154  and, as can be seen in  FIG. 3B , once the canister is brought into association with the block, these O-rings form a gas-tight association with the external wall of the canister blank, thus hindering pressurized gas flow out of the opening  148 . As can further be seen in  FIG. 3B , once the canister blank is in tight association with the block, the upper portion of the neck protrudes into working space  142 . The working space houses a piston  160  that can axially reciprocate between the first piston position, seen in  FIG. 3B , and the second piston position, seen in  FIG. 3E , that is more proximal to the end wall  146 . O-rings  162 ,  164  accommodated within circumferential grooves in side walls  144 , provide for gas-tight association between piston  160  and side walls  144 . 
         [0240]    Piston  160  also has an axial bore  166  accommodating plunger  170  that can also axially reciprocate between the first plunger position, shown in  FIG. 3A  or  3 B, and the second plunger position, shown in  FIG. 3C . In the latter position, the plunger  170  brings plug device  110  fully into the upper portion  112  of neck  104 . The internal bore  166  also includes two circumferential grooves accommodating O-rings  172 ,  174  providing for gas-tight association between plunger  170  and walls of the bore  166 . Formed at the center of leading face  176  of piston  160  is a depression  178  having a circular perimeter with dimensions corresponding to the external perimeter of upper portion  112  of neck  104 . Working space  142  is linked to a gas conduit  136 , which in turn is linked to a pressurized gas source shown schematically as rectangle  138  for control of the pressurized gas flow into working space  142 . 
         [0241]    The sequence of operations will now be described with reference to distinct steps shown in  FIGS. 3A-3F . It should be noted that some of the described steps or details within them may be performed in different sequences or the performance of some may be partially or entirely overlap one another in the time of their performance. 
         [0242]    Preparatory to the step shown in  FIG. 3A , a plug device  110  is fitted at leading end of plunger  170  which has a circular bulging member that fits into the cavity of plug device  110 . Canister blank  132 , as shown in  FIG. 3B , is brought into tight association with seat  150 . Then pressurized gas, typically carbon dioxide, is released into working space  142  through conduit  136 , as represented by arrow  190  and from there enters enclosure  103 . When reaching the desired pressure, the flow of gas may be stopped and, given the gas-tight seal maintained by the gas-tights engagement of the different elements, the pressure will be maintained. Alternatively, the link to the pressurized gas may be maintained to compensate for minor pressure loss. 
         [0243]    In the next step, shown schematically in  FIG. 3C , plunger  170  is displaced from its first to its second plunger position, thus inserting plug device  110  into the terminal bore  134  until its bottom end  120  rests on shoulders  118 . 
         [0244]    In the next step, shown in  FIG. 3D , piston  160  is axially displaced and when reaching the position shown in  FIG. 3D , it begins to exert pressure on lips  114  and through additional downward displacement of the piston to the second piston position, shown in  FIG. 3E , the upper portion is deformed to tightly fit around the external face of plug  110 , this deformation including the internal bending of lips  114 . The piston  160  and plunger  170  are then retracted to their respective first positions, as shown in  FIG. 3F  and then the canister, filled with pressurized gas and sealed by a rupturable single use plug, can be removed; and the cycle may be repeated again. 
         [0245]    Reference is now made to  FIGS. 4A and 4B  showing schematic cross-section representations of the upper part of the canister and of the coupling element  200 , which is part of the appliance or system schematically represented by block  221 . Canister  102  with neck  104  fitted with a plug device  110  is brought into association with coupling element  200 , both of which are shown separated from one another in  FIG. 4A  The coupling element includes a coupling body  202  having a cavity  204  with internal threading  206  and including in its center a spiked gas-channeling member  208 . Gas-channeling member  208  has an elongated shaft  210 , tapered end  212 , openings  214  proximal to the tapered end leading into lumen  216 , linked to a gas conduit  220  that is, in turn, linked to the pressurized gas conduit sub-system (not shown) of the appliance or system  221 . 
         [0246]    The spiked member has a base  223  that is accommodated in seat  224 , the seat including also O-rings  222  to ensure gas-tight association. The accommodation of base  223  in seat  224  may, for example, be through a screw-type engagement. 
         [0247]    The coupling between the coupling element and the canister neck is, in this case, a screwed type engagement; but, as can be appreciated, this is an example only of a variety of other coupling arrangements. Upon coupling, the spike member penetrates cavity  124  within plug  110  and by further screwing, as shown in  FIG. 4C , it penetrates through bore  122  and ruptures barrier element  126  and consequently openings  214  come into contact with the pressurized gas in the canister and permit passage of the gas through them and through lumen  216  into the gas conduit sub-system of the appliance or system. O-rings  128  provide for gas-tight association between shaft  210  and internal walls of the plug. 
         [0248]    Reference is now made to  FIGS. 5A-8B : In these Figures like reference numerals are used as in  FIGS. 2A and 3A , shifted by  200  ( FIGS. 5A-5B ),  300  ( FIGS. 6A-6B ),  400  ( FIGS. 7A-7B ) and  500  ( FIGS. 8A-8B ) to mark like elements. 
         [0249]    In the embodiments of  FIGS. 5A and 5B , plug  310  is formed with an annular groove  321  accommodating an O-ring  323 . Barrier element in the form of a thin metal sheet  326  is tightly and sealingly fixed at the inner end  325  of the plug by welding. The plug may be fitted within cavity  334  through welding or through crimping (in the latter case in a manner analogous to that described in  FIGS. 3A-3F ). As can further be seen in  FIG. 5B , the neck of the canister blank is formed with a lateral bore  329  linking cavity  334  to the external environment. In the event that pressure within the canister increases to an excessively high level, e.g. as a result of heating, through the clearance  331  between the bottom portion of the plug and the side walls of cavity  334  the pressure will impact O-ring  323  and cause it to deform to such an extent as to permit gas release out of bore  329  to thereby reduce the pressure to safe level. 
         [0250]    The plug  310 A shown in an explode view in  FIG. 5C , is structurally similar to the plug  310  of  FIGS. 5A and 5B  and elements having a similar function have been given like numbers with and “A” indication. The main difference is in that the barrier element  326 A has the shape of a dish formed with upright walls  327  that fit around the base  329  of the plug body  310 A. The barrier element  326 A may be pressure fitted to base  329 , may be welded or held tightly by pressing the plug body  310 A against an auxiliary member or against shoulders formed within the canister neck&#39;s cavity in an analogous manner to that described in connections with  FIGS. 7A and 7B . 
         [0251]    In the embodiments of  FIGS. 6A and 6B , the thin metal sheet  426  serving as a barrier element is secured in position by tight screw engagement between the plug&#39;s body  441  and auxiliary member  443 , which is screw fitted into the opening at the inner end of body  441  (through external threading at the former and matching internal threading of the latter). Other than this, the plug in this embodiment is functionally similar to that of  FIGS. 5A and 5B . 
         [0252]    In  FIGS. 7A and 7B  the thin metal sheet  526  is also held between plug body  541  and auxiliary member  543 ; but, rather than screw fitting the plug body and the auxiliary member are fitted tightly one against the other while inserting them into cavity  534  during the manufacturing process, thus holding sheet  546  between them. Alternatively the auxiliary member  543  may also be welded to plug body  541 . 
         [0253]    Similarly as in the case of the embodiments of  FIGS. 5A and 5B , the plug of embodiments of  FIGS. 6A-7B  may be secured in position through welding or pressure crimping. 
         [0254]    In the embodiments of  FIGS. 8A and 8B  the auxiliary member  643  may be fitted together with plug body  641  by screw-engagement, by welding, etc. and this assembly may then be fitted into cavity  634  is by screw tight engagement through external threading in the outer face of the plug body and internal threading within the cavity. 
         [0255]      FIGS. 9A and 9B  show a plug  650  that includes plug body  652  defining a central bore  654  with an annular groove  656  accommodating O-ring  658 . Barrier element  660  is fitted at the bottom of body  652 , for example by welding. Plug  650  is of the kind used in the canister of  FIGS. 15A and 15B , to be described below, and is constituted by a first, main body section  662  and an upper, second body section  664  of narrower diameter defining between them shoulder  666 . In use, as can be seen in  FIG. 15B , the upper body section protrudes above the upper end of the canister&#39;s neck with the main body section  664  being in tight association with the walls of the cavity of the canister while the upper end of the walls being folded as lips over shoulder  666  to thereby ensure tight fitting of the plug in the containers neck cavity. 
         [0256]    All the embodiments of the plug, shown above, are various configurations of a barrier element and a plug body that are separately produced and are assembled and tightly fitted to one another in a gas-tight manner, to thereby form the plug. It should be noted, however, that it is also possible, under other embodiments of this disclosure, to construct the plug body and the barrier element out of a single integral metal block, e.g. through machining, a die casting or a combination of the two. 
         [0257]    Reference is now being made to  FIGS. 10A-10D  showing the upper portion of a canister  102  where the neck  104  accommodates a plug  650 , of the kind shown in  FIGS. 9A-9B  and, also, a flow-restricting element  674  situated interior (or below, in the orientation of the canister in these figures) to plug  650 . Plug  650  is held within the upper part of neck  104  between lips  114 , tightly holding the plug in its upper end, and between disk  670  that define a central void  672 . The flow-restricting element  674  that is situated below disk  670  includes a nesting member  676  and a spherical floating member  678 . As can best be seen in  FIG. 10C , nesting member  676  has an upper segment  680  that is snugly associated with the surrounding inner walls of the neck and has a slanted lower surface  682  that defines a seat for member  678 . The lower segment  684  of nesting member  676  has arms that define a cage between them that accommodates member  678  and are provided with displacement-restricting abutments  686  that limit the downward vertical displacement of member  678 . Consequently, member  678  can vertically displace between an uppermost position in which it is seated in seat  682  and a lowermost position, in which it rests on abutments  686 , as seen in  FIG. 10A . 
         [0258]    In  FIG. 10A , barrier element  660  is intact and accordingly there is no outflow of gas. Once barrier element  660  is pierced, gas outflows and, consequently, floating member  678  moves upward with the gas to come to rest within seat  682 . In this position of member  678  gas outflow is limited, whereas as long as member  678  is removed from seat  682 , gas can outflow in a unrestricted manner 
         [0259]    Upon coupling of the canister&#39;s neck with gas-channeling member  208 , shaft  210  penetrates through lumen  122 , in a manner similar to that described above, to rupture barrier  660  and in its fully coupled state, openings  214  come to be positioned within void  672 . At this state the tapered end  212  of the shaft limits the upward displacement of member  678 , as seen in  FIG. 10B  and gas outflows through a flow path represented by arrow  690 . This gas outflow causes upward displacement of member  678  to the position seen in  FIG. 10B . 
         [0260]    In the event of premature decoupling, when there is still gas pressure remaining within the canister, the pressure differential between the canister&#39;s interior and the exterior will cause upward displacement of floating member  678  to its fully upward position to rest within seat  682 . 
         [0261]    As can best be seen in  FIG. 10D , seat  682  is formed with a vertical notch  692  that defines an open gas channel that permits gas outflow even when member  678  is seated in seat  682 . This then enables trickled gas outflow and, hence, gradual pressure reduction from within the canister. Thus, according to this embodiment, in the event of decoupling, gas pressure will not be released in a burst but will rather be gradual and also relatively quiet. 
         [0262]    In the embodiments shown in  FIGS. 10A-10D , the floating member is made to be light, e.g. is a hollow member or made of a low-density material, such as a low density polymeric material, foamed polymers, thin-walled aluminum hollow sphere, etc. As can be appreciated, in other embodiments, member  678  may also be biased into its seated position by biasing elements, e.g. a spring. Furthermore, in other embodiments, the member may have shapes other than spherical. 
         [0263]    Referring now to  FIGS. 11A and 11B , shown is a coupling device  702  for coupling to a canister  700  (illustrated in  FIGS. 12A and 12B ). The device is configured for coupling to the canister in a screw-type manner, at its one end  791  and for coupling to the gas-port of the appliance or system, again in a screw-type manner, at its other end  792 . It should be noted that screw-type coupling is an example and other means of coupling may be used (e.g. snap fit coupling, latches-based coupling, bayonet type coupling and others). 
         [0264]    Device  702  is comprised of device body  704 , a cup-shaped connector element  706  and gas channeling member  708  at end  791 , safety plug  718 , and valve element  724  at end  792 . Gas channeling member  708  has a structure similar to gas channeling member  208  shown in  FIG. 4B  and includes a shaft  709  with a tapered end  712  having openings  714  leading into lumen  716 . Lumen  716  is part of a gas conduit, marked  738  that extends between the two ends  791 ,  792  and includes also spring-accommodating cavity  734  and valve-accommodating cavity  736 . 
         [0265]    Member  708  has a base  723  which is fitted within a seat  724  and is configured with a lateral groove  725  accommodating O-ring  722  that provides for a gas-tight seal to avoid leakage out of said gas conduit. 
         [0266]    The shaft  709  of member  708  protrudes into cavity  730  within cup-shaped connector element  706 , the side walls of which are internally threaded (the threading—not shown). Connector element  706  is constituted by side walls which extend from body  704  and by a fastening element  732  that is coupled to said walls in a screw-type manner. Turning of the fastening ring  732  will distance it away from the member and owing to the outwardly tapering contour of the neck the external lips of ring  732  will then bear tightly against the tapering portion to thereby secure the coupling of the coupling device to the canister. 
         [0267]    The other end of the device has an external, coarse screw threading  740  for coupling with a matching connector (not shown) of an appliance or system. 
         [0268]    Valve  744  includes a base  746 , plunger  748 , spring  750  and O-ring  752 . Plunger  748  has a stem  754  that is accommodated within bore  756  in base  746  and can axially displace against the biasing force of spring  750  that is accommodated with spring-accommodating cavity  734 . In the position shown in  FIG. 11B , the plunger is in its fully biased state with its shoulders  758  pressed against base  746  and O-ring  752 , accommodated within circular groove  760 , thereby sealing egress of gas out of valve-accommodating cavity  756 . Once coupled with said device or appliance, stem  754  is pushed against the bias of spring  750  causing shoulders  758  to distance from base  746 , thus permitting gas egress through the clearance between stem  754  and bore  756 . Base  746  is fitted within cavity  736  in a screw type engagement and is associated with O-ring  762  to ensure a gas-tight association between the base and the device. 
         [0269]    Cavity  766  accommodates safety plug  764  and is linked through conduit  768  to spring-accommodating cavity  734 . The conduit  768  is sealed by membrane  770  and when pressure increases above a defined threshold level, membrane  770  opens permitting gas release to the outside. 
         [0270]      FIGS. 12A and 12B  show a coupling device of the kind described above coupled to a canister. As can now be better understood, turning of fastening element  732  so that it will be downwardly displaced, in the direction of arrow A, will press lips  772  against the wider portion of the neck to thereby practically lock the device in this coupling position. Once so coupled, as explained above, coupling of the device with the appliance or system at its other end will cause gas flow through said conduit into the gas-port of the appliance or system (not shown). 
         [0271]    Reference is now being made to  FIGS. 13-15B  showing a coupling device, generally designated  1000 , of another embodiment which, as already noted above, includes a safety arrangement that prevents premature or accidental decoupling between the device and a pressurized carbon dioxide canister, namely, decoupling it while there is still carbon dioxide pressure in the canister exceeding a predetermined gas pressure. 
         [0272]    In  FIGS. 12-14B , the same reference numerals as those used in  FIGS. 11A-12B  have been used with the indication “A” to denote elements having the same or similar function. Thus, by way of example, element  746  of  FIGS. 11A and 11B  will be equivalent to element  746 A of the embodiment of  FIGS. 13-15B . The reader is referred to the description above of the embodiments of  FIGS. 11A-12B  for explanation of the role and/or function of these elements. The description below will focus primarily on those elements that are distinct from the embodiments described above. 
         [0273]    Coupling device  1000  has a base portion  1002  and accommodates a cup-shaped cavity  730 A that is internally screw-threaded and adapted for screw-tight coupling with the neck of a canister. 
         [0274]    Fitted over the base portion  1002  is a ring element  1004  having an internal guiding projection  1006  that fits into groove  1008  defined on the exterior of base portion  1002 , to thereby guide circular rotation of ring  1004 . Accommodated in groove  1008  is also a helical spring  1010  that rests against projection  1006  at its one end and a barrier at the end of groove  1008  (not shown). The urging force of spring  1010  biases the ring to rotate in a direction represented by arrow  1012  (clockwise in  FIG. 13 ) into the ring&#39;s locking state. The ring is secured into position by means of fastening ring  1020 . 
         [0275]    Coupling device  1000  also includes a safety bolt  1022  which fits into bore  1024  and has an associated spring  1026  that biases the bolt element in a radial direction from a first, locking position to a second, releasing position of the bolt. Safety bolt  1022 , as can be seen in  FIGS. 14B and 15B , has a projection  1028 , that upon coupling of the coupling device  1000  with the neck of canister  700 A, can, when the bolt is in its locking position, fit into and be accommodated in groove  1030  formed in the canister&#39;s neck, as can be seen in  FIG. 15B . As long as bolt  1022  is in its locking position in which projection  1028  is accommodated within groove  1030 , coupling device  1000  cannot be decoupled from the canister. 
         [0276]    The safety arrangement of this embodiment includes, in addition to safety bolt  1022 , also blocking pin  1032  that is accommodated in pin bore  1034 . Pin  1032  has a broader shoulder  1036  at its rear end, snugly associated with the walls of pin bore  1032  having a lateral groove accommodating an O-ring  1038  that forms a gas tight seal with the walls of bore  1032  and thereby defining a head space  1042 . Head space  1042  is linked through lateral bore  1044  to cavity  734 A, which is part of the gas conduit  738 A within the coupling device. 
         [0277]    When pressurized gas enters the head space  1042  through lateral bore  1044 , it applies downward pressure on pin  1032  which is then axially displaced from its position shown in  FIG. 14B  towards bolt  1022  to position seen in  FIG. 15B , in which the tip  1046  of the pin is accommodated into a matching peripheral groove  1048  of bolt  1022 , to thereby locking bolt  1022  in the position shown in  FIGS. 14B and 15B , in which projection  1028  is accommodated within groove  1030 . In this state the device cannot be decoupled from the canister, as explained above. 
         [0278]    Pin  1032  is associated with spring  1050  that provides a biasing force on the pin in a direction away from bolt  1022 . Once pressure in the canister and consequently also in head space  1042  is reduced below a certain pressure (that is a pressure defined by the properties of the spring, where the force acting by the gas pressure on shoulders  1036  equals the opposite biasing force of the spring), pin  1032  can then be displaced away from the bolt, by the force of the spring to the position shown in  FIG. 14B , thereby permitting radial displacement of bolt  1022  to its unlocking position. 
         [0279]    Ring  1004  has an abutment  1054 , seen cross-section in  FIG. 14B , which during rotation of the ring slides over track  1014 . When abutment  1054  comes to rest over bolt  1022 , it pushes the bolt into its locking position. Once the ring is rotated against the bias of spring  1008 , the bolt can be displaced away from the neck to permit decoupling. 
         [0280]    Locking of the coupling device  1000  onto the neck of a canister, upon coupling, is in fact automatic. Once the canister&#39;s neck is coupled with the device, as seen in  FIG. 15B , barrier element  660  is ruptured by the tip  712 A of elongated shaft  709 A, whereby pressurized gas can enter into the gas ducting system  738 A and from there to head space  1042  of bore  1034 . Consequently, the gas pressure in the canister and in the head space  1042  of bore  1034  will be the same. This pressure then forces pin  1032  to displace against the bias of spring  1050 . Ring  1004  is biased into a locking state by spring  1010  whereupon abutment  1054  forces bolt  1022  into its locking position, as shown in FIG.  15 B against the bias of spring  1026 , whereupon pin  1032  can move downward locking bolt  1022  and lock it in its locking position. 
         [0281]    Reference is now being made to  FIGS. 16A-16C  showing neck  804  of a canister having a flow-restricting element of the kind similar to that shown in  FIGS. 10A-10D ; and, accordingly, like reference numerals are used shifted by 200 to define like elements. The reader is referred to the description of  FIGS. 10A-10D  for an explanation of structure and function. 
         [0282]    The coupling element  808 , which in this embodiment forms a functional element of an appliance or system (although similar functional coupling features may also be included in a coupling element that is an independent device), includes a shaft  810  with a shaft end  812  that in the coupling state, shown in  FIG. 16A , bears on floating member  878  to permit gas flow through apertures  814  into lumen  816  and from there to the gas conduit, an initial segment thereof  820  being seen in this figure. 
         [0283]    Shaft  810  is formed with a peripheral axial recess  822  that extends upward from shaft end  812  and ending at shoulders  824 . In the coupled state shown in  FIG. 16A , gas outflow along the periphery of the shaft is prevented by O-ring  858 . 
         [0284]    During decoupling, as seen in  FIG. 16B , the shaft is relatively axially displaced away from the neck and, once shoulders  824  extend upwards to O-ring  858 , the recess  822  permits gas outflow along the lines represented by arrow  890 . This enables controlled release of pressure, avoiding violent release of pressure in the fully decoupled state shown in  FIG. 16C . In this case, such violent release is further avoided by the flow-restricting element  874 . 
         [0285]    Reference is now made to  FIGS. 17A and 17B  showing two different examples of multipacks (6-pack in these examples)  900 ,  950  of canisters of the kind described above. Each one includes respective holding racks  902 ,  952  for canisters  100  and integral carrying handles  904 ,  954 . The racks and the handles may, for example, be made of plastic or cardboard.