Abstract:
The present invention relates to a transport container which provides mechanical and thermal stability for a load and which container is fabricated as the container is loaded. In particular, the present invention relates to a container which can be readily transported on aircraft, such as an aircraft container. In the field of logistics, that is the field of movement and supply of produce and materials, in particular in the transport of intermediate and finished products, containers have been developed which safely protect from physical damage a wide variety of product. Food and pharmaceutical products not only need protection from physical shock and pressures but also require temperature stability during transportation; otherwise goods can be damaged and be unusable, whether such damage is apparent or not. However, air transport poses a particular problem: Goods can be transported in tropical heat, packaged and placed upon pallets and the like containers whereby they are presented in aircraft style containers. Such goods may be left on runways at extreme temperatures (+40° C.) and then placed within a hold where low pressures and low temperatures exist during flight. At a destination airport the temperatures may well be sub-zero. To simplify transport with respect to airports, planes and handling equipment, there have been developed aircraft Unit Load Devices (ULDs) which comprise any type of pallet or container that can easily be loaded to the aircraft by a ground handler. The present invention seeks to provide a transport container which can maintain goods within a narrow temperature range, can displace a considerably reduced volume before erection, is economical to manufacture, can readily and easily be constructed. The present invention further seeks to provide a transport container which is compatible with standard Unit Load Device specifications.

Description:
FIELD OF INVENTION 
       [0001]    The present invention relates to a transport container which provides mechanical and thermal stability for a load and which container is fabricated as the container is loaded. In particular, the present invention relates to a container which can be readily transported on aircraft, such as an aircraft container. 
       BACKGROUND TO THE INVENTION 
       [0002]    In the field of logistics, that is the field of movement and supply of produce and materials, in particular in the transport of intermediate and finished products, containers have been developed which safely protect from physical damage a wide variety of product. Food and pharmaceutical products not only need protection from physical shock and pressures but also require temperature stability during transportation; otherwise goods can be damaged and be unusable, whether such damage is apparent or not. 
         [0003]    For example, in the pharmaceutical industry, product often needs to be maintained within a temperature range: product may be packed in relatively small containers, which containers are relatively fragile—accordingly insulation must provide both physical and thermal stability. Equally, in the food industry, fish suppliers will often have chilled fish boxes which are designed to accept, say 20 Kg of product. The fish must be maintained at low temperatures, yet will be placed in containers which require a high degree of strength to prevent spillage. 
         [0004]    As the standards of living increases, in developed markets, for example in Europe and North America, tropical foods—that is foods grown in far-away tropical places—are increasingly being stocked by supermarkets, delicatessens and the like. Short pick to distribution centre times in the producing country are matched by air carriers taking goods to the countries of consumption in similar lengths of time, whereby it is not uncommon for fruit to be on the plates of householders within two to three days of having been picked in a far-away country. 
         [0005]    However, air transport poses a particular problem: Goods can be transported in tropical heat, packaged and placed upon pallets and the like containers whereby they are presented in aircraft style containers. Such goods may be left on runways at extreme temperatures (+40° C.) and then placed within a hold where low pressures and low temperatures exist during flight. At a destination airport the temperatures may well be sub-zero. A corollary to this is the production of temperature sensitive pharmaceuticals in a “developed” country which pharmaceuticals must be transported to another side of the world with similar temperature variations. 
         [0006]    Both the above scenarios place transport managers in difficult positions. For air haulage, containers should weigh little, make use of non-rectangular hold spaces within aircraft; for the goods, they must be protected from shock, be maintained within a narrow temperature range, sometimes being equipped with temperature data loggers whereby a record of temperature within a container may determine whether or not a pharmaceutical is destroyed prior to use because of poor temperature handling. Refrigeration units may be provided with a container whereby temperatures maybe maintained, but then a source of electrical power or fuel for a powered generator is required. 
         [0007]    To simplify transport with respect to airports, planes and handling equipment, there have been developed aircraft Unit Load Devices (ULDs) which comprise any type of pallet or container that can easily be loaded to the aircraft by a ground handler. Aircraft ULDs are units which interface directly with an aircraft loading and restraint system, without the use of supplementary equipment. There are pre-defined ULDs, such as LD3, LD7, which correspond to standard configurations and can be utilised on certain types of aircraft. There are still further ULDs that are shaped such that they have a rectangular base yet are not generally cylindrical, that is to say they extend outwardly, beyond the sides of the base, as they extend upwardly from the base. There is also an increasing demand for many containers, especially aircraft ULDs that they are transported from a supplier in a flat-pack fashion and they are constructed prior to use. This enables warehousing requirements to be reduced by typically 66-75%. 
         [0008]    EP1025405 provides a container which has its cavity bounded by boundary elements, comprising a roof element, floor element, side walls and an end element. The boundary elements contain wall cores of hard foam plastics such as polyurethane. The rail core is edged with edging beams of fibre-reinforced plastics. The boundary elements are fixed rigidly to each other on connecting surfaces in the region of the edge beams. Standard doors can be used. Glass-fibre-reinforced plastics panels are combined with steel components to provide an assembly which whilst strong is not capable of being dismantled. 
         [0009]    U.S. Pat. No. 4,266,670 provides a collapsible, reinforced, four sided container attached to a rigid base, of the type for transporting heavy products, such as iron. This design is collapsible whereby on a return journey it may be shipped in reduced size for reuse. This container is manufactured from reinforced corrugated cardboard. An example of this teaching is shown in  FIG. 1 , which container  10  comprises a pallet base  40 , upon which are placed side panels  10 - 13 . Each of the side panels have complementary edges having mortise and tenon elements, with an aperture running through, whereby stakes  107 - 110  may be inserted to enable the sides to remain upright. The panels provide a limited amount of temperature insulation, especially taking into account the relatively large size of the cardboard panels, being approximately 15 cm thick. One side may be easily opened for loading or unloading. 
         [0010]    U.S. Pat. No. 2,556,418 provides a thermally insulated container and pallet. Telescopic tubes are mounted upon each of the four corners of a pallet to provide an enclosure frame which is built up with canvas straps and subsequently insulated. Refrigerant gasses may be introduced into the enclosure once a canvas wrap is positioned around the container. 
         [0011]    GB1382230 provides a heat-insulating protective cover for temperature-sensitive goods comprises a carrier frame adapted to be positioned over the top surface of the goods, which rest on a pallet, and provided with support legs for this purpose. Walls of flexible heat-insulating material extend around the carrier frame and can be lowered from a retracted position to a lowered position, the walls being connected at their upper edges to a layer of heat-insulating material. Lift ropes are attached to the lower edges of the walls and extend up through eyelets to a common pull rope so as to permit the simultaneous lifting of all the walls to an upper position adjacent the carrier frame. The lower edges of the walls are provided with rings adapted to be hooked on to co-operating hooks on the pallet to provide a heat insulating space between the pallet and the carrier frame. 
         [0012]    U.S. Pat. No. 3,955,700 teaches of an aircraft container which has a moulded reinforced fibreglass enclosure, which has two removable panels on one side which provide access to the interior. Whilst this solution provides a strong and rigid—yet resilient—container, when empty the container takes as much space as when full, which is not acceptable for many supply industries. Furthermore, by providing an enclosure, limitations are placed with respect to the order of packing and the addition of goods to be despatched, which can provide complications and expense to any freight manager. 
         [0013]    It is notable that there are few thermally insulating cargo containers; either they are rigid yet not collapsible or are collapsible yet easily damaged when shifted by fork-lifts and other and/or are complex to assemble. 
       OBJECT OF THE INVENTION 
       [0014]    The present invention seeks to provide a solution to the problems addressed above. The present invention seeks to provide a transport container which can be manufactured at low cost and can readily and easily be constructed. The present invention seeks to provide a transport container which can be erected at point of use. Furthermore, the present invention seeks to provide a container that when completed can maintain goods within a narrow temperature range. 
         [0015]    The present invention further seeks to provide a transport container which is compatible with standard Unit Load Device specifications. 
       STATEMENT OF INVENTION 
       [0016]    In accordance with a general aspect of the invention, there is provided a thermally insulating collapsible transport container fabricated from at least one set of co-operating first and second panels arranged substantially at right angles to one another, the first and second panels having first (outside) and second (inside) major surfaces and a circumferential edge portion, wherein a first panel defines a rebated channel on an inside face of the panel, the channel being adjacent to at least one edge, the rebate being defined in cross-section by an edge face of the panel and a general L-shape, a first arm of the L-shape section defining, in use, part of the outside wall of the first member, the second arm of the L-shape section having an inside face opposing said edge face of the panel, whereby to define a rebate into which an edge portion of the second panel can be received and resiliently retained therein. By having separate panels resiliently retained, air passage between an inside and an outside of a container is prevented. 
         [0017]    Conveniently, the container comprises at least a base and upstanding wall panels, wherein the base panel corresponds to the first panel type and the wall panels correspond to the second panel type. Conveniently, the panels are of rectangular shape in plan view. The container can have a variety of forms, but a rectangular box would be the most frequently employed, even though it would be possible to have square section or cylindrical section boxes; indeed, the walls could be non-vertical, at least in part. Preferably, the container further comprises one or more insulating cover panels, which insulating cover panels correspond in type with either the first or second panel type, whereby the cover panel can be resiliently retained with respect to an upstanding wall panel. By having separate panels resiliently retained, air passage between an inside and an outside of a container is prevented. 
         [0018]    The insulating panels can be fabricated from one or more types of panel including extruded polystyrene, polyurethane foam, expanded polystyrene, cardboard, laminated polyurethane foam, laminated expanded polystyrene, or moulded plastics. The laminate face can comprise one of card, plywood, polypropylene, aluminium or steel. The L-section of the panel may be formed as an integral part of the panel when, for example it is moulded, part of a reinforced plastics (resin) moulding or, formed by the addition of an “L” section member to an insulating panel, for example, an inside face of an “L” section member is attached by adhesive (for example) to an outside edge of the insulating panel, a second inside edge of the “L” section member facing an edge portion, rebated or otherwise, of the insulating panel member. The separate L-shape members can conveniently be made from one of wood pulp, polypropylene, aluminium, glass fibre, resin, carbon fibre. The edge portion of the first panel can be stepped, wherein, in use, the edge portion of the second panel abuts against a portion of the step. 
         [0019]    In use, the base member may be positioned upon a pallet and subsequently placed upon an aircraft container base. In the alternative, feet depend from the base so as to dispense with a pallet, which is beneficial in certain loading environments, where natural products such as wood pallets are not welcome in view of the possible contamination in clean-area loading bays. 
         [0020]    Conveniently, a weatherproof sheet is arranged about the assembled container in use. Preferably, the weatherproof sheet provides a thermal barrier. Conveniently the weatherproof sheet is retained by a cargo net, which attaches within a recess of a pallet base to provide an integrated weatherproof container system. A thermal sheet can surround the panels and can be retained by a cargo net. Conveniently, the cargo net comprises any one or more of webbing or elasticated cords. Conveniently, the net has feet which locate into channels defined along peripheral edges of the base or into an aircraft unit load base formed with sheet aluminium, aluminium alloy or alternative material. 
         [0021]    In accordance with another aspect of the invention, there is provided a method of fabricating a transport container, wherein the container comprises at least one set of co-operating first and second panels arranged substantially at right angles to one another, the first and second panels having first outside and second inside major surfaces and a circumferential edge portion, wherein a first panel having a general L-shape cross-section element defines a rebate along an edge portion and is operable to accept an edge portion of the second panel, a first arm of the L-shape section comprising part of the outside wall of the first member, the second arm of the L-shape section opposing an edge face of the first pane, wherein the method includes the step of introducing an edge portion of a second panel into the rebate, urging an outer face of the second panel against an inside face of the upstanding arm of the L-shape member, until the edge of the second panel abuts an inside rebate surface, whereby first and second panels can be resiliently retained, one with respect to another. By repeating the steps with respect to associated adjacent edges, a container can be simply formed. 
         [0022]    Conveniently, the container comprises base elements and wall panels wherein the base and wall panels cooperate with respect to each other as first and second panels. The first and second wall elements about a corner section can cooperate with respect to each other as first and second panels. Preferably, the container further includes top panels, wherein the container comprises top and wall panels cooperate with respect to each other as first and second panels. 
         [0023]    The base, sidewall and top members are conveniently flat panels, made of extruded polystyrene, expanded polyurethane or polyethylene foam. Conveniently, the foam panels are laminated whereby to provide optimum rigidity, with a light weight, with good thermal barrier properties. Ideally, the edges of any adjoining co-planar panel members have complimentary rebates. An advantage arising from the use of materials such as polyethylene foam means that thermal insulation and physical shock protection is extremely high with regard to known container systems. The L-section member can be integrally moulded, using a glass reinforced plastics material exterior laminate, which is secured to plastics foam elements, for insulation. 
         [0024]    In accordance with a still further aspect of the invention, there is provided a container having on an inside surface of a wall an envelope for supporting a temperature control pack, the envelope comprising an aperture having a width and a depth to accommodate one or more temperature control packs, the temperature control pack being spaced from a product within the container by a spacer element. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0025]    For a better understanding of the present invention, reference will now be made, by way of example only, to the Figures as shown in the accompanying drawing sheets, wherein:— 
           [0026]      FIG. 1  illustrates a prior-art transport container; 
           [0027]      FIGS. 2   a  &amp;  2   b  illustrate a first embodiment of the invention in assembled form, upon an air pallet and with weatherproofing in place; 
           [0028]      FIG. 3   a  details a base member in accordance with the invention; 
           [0029]      FIG. 3   b  details a base member per  FIG. 3   a  with a side member partly inserted; 
           [0030]      FIG. 3   c  details a base member per  FIG. 3   a  with a side member fully inserted; 
           [0031]      FIG. 3   d  details an alternative arrangement; 
           [0032]      FIGS. 4 ,  5   a  &amp;  5   b  show exploded views of the first, second and third embodiments; 
           [0033]      FIG. 5   c - e  shows a first, second and third thermal mass envelopes or sleeves; 
           [0034]      FIGS. 6 ,  6   a  &amp;  6   b  shows a pallet base and details thereof; 
           [0035]      FIG. 7  shows a fourth embodiment; 
           [0036]      FIGS. 8 &amp; 9  show view of the base in upturned and normal positions; and, 
           [0037]      FIGS. 10 &amp; 11  show further views of the fourth embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0038]    There will now be described, by way of example only, the best mode contemplated by the inventor for carrying out the present invention. In the following description, numerous specific details are set out in order to provide a complete understanding to the present invention. It will be apparent to those skilled in the art, that the present invention may be put into practice with variations of the specific. 
         [0039]      FIG. 2  shows a first embodiment  20  of the invention in an assembled state. Whilst a base panel is not shown in any detail, outwardly extending the L-section corner sections (to be referred to as L-members hereinafter)  32  depending from the base panel are shown. These L-members are derived from corner guards as used in the packaging industry, (where they are also referred to as V-boards) which are typically retained in place with plastics wrapping film and or polystyrene mouldings about a package. 
         [0040]    The top panels, in this embodiment correspond from an outward perspective, to the base panel, each comprise three panels, which are made from an insulating material such as extruded polystyrene, polyurethane, expanded polystyrene or may comprise a composite panel, as will be discussed below. Similarly, the long sides of the container comprise three panels,  23   a ,  23   b ,  23   c . The outer edges of the panels  23   a  and  23   c  each have an L-member  32  attached thereto. The short sides of the container comprise two panels  23   a ,  23   b . Conveniently, either the outer panels of the long side,  22   a ,  22   c  have an L-member as shown, or the panels  23   a ,  23   b  have an L-member. When used with an air pallet, to comprise a ULD shipment, the container in accordance with the invention will be placed upon such an air pallet  25  and a cargo net  26  will be strapped around the container as shown in  FIG. 2   b . Whilst the insulating panels closely fit together to prevent gaseous exchange—and this heat transfer—it is common for thermally insulating outer bags to be employed in the transport of temperature sensitive produce and such a bag could be placed around the container and be secured by the cargo net  26 . The cargo net will have ground anchor devices which locate into an air cargo pallet as will be detailed later. 
         [0041]      FIG. 3   a  shows part of a base member  31 . Conveniently, the material would comprise extruded polystyrene or polyurethane foam and have a thickness of approximately 50-80 mm. Reference numeral  32  refers to an L-member in accordance with the invention, the member being rigid and is fabricated from a number of possible materials, such as wood-pulp, aluminium, steel, polypropylene, glass fibre, carbon fibre, for example. The thickness of the L-member is dependent upon the material form which it is manufactured, but for wood-pulp, a thickness of 4-6 mm is typical. Importantly, this will not have any appreciable affect upon the manner of the base sitting upon a pallet etc., for example. The exact dimension of the L-member will vary upon application, but for the example shown, the horizontal arm is 90 mm and the vertical arm, at 50 mm corresponds with the height of the insulating base material—primarily since the container will be loaded prior to erection of the sided walls and therefore the vertical arm should not extend above the height of the insulating material since it would otherwise be susceptible of being damaged by the forks of a forklift truck as the load is placed upon the base. If the load were to be lifted by crane, for example, then the height of the vertical arm would not be so critical. It has been found that the L-member can be attached to the insulating panel by a double-sided tape, such as Thorn-Carless product 95623-M, which is a solvent-free modified acrylic adhesive and has a thickness of approximately 0.23 mm. In  FIG. 3   b , there is shown a lower edge of a side panel  33  being inserted between the L-member and the insulating material of the base, the upstanding arm of the L-member being urged outwardly in the direction shown by arrow A, to enable insertion of the panel  33 . Conveniently, the internal angle of the L-member is less than 90°, for example in the range of 82°-88°, whereby the side member is resiliently retained within the rebate defined by the base insulating member and the L-member, as shown in  FIG. 3   c , the upstanding leg of the L-member acting towards the upstanding panel in the direction shown by arrow B. To attach the L-member by, for example, screws could compromise the thermal insulation properties of the insulating material, but may be preferred in certain circumstances.  FIG. 3   d  shows an alternative, wherein the base member comprises a stepped rebate; other variations are also possible. Notwithstanding the above, the side members may be introduced into the channel or rebate defined between the L-member and the base (or other co-operating wall—wall or wall-top sections) such that the tongue of the introduced panel member is resiliently squeezed, without causing the L member to be urged outwardly or to be urged outwardly relatively insignificantly. The portion of the tongue of the panel that is introduced into the rebate may be coated with a plastics coating such as a Teflon® spray, which increases the durability of the tongue, in the event that repeated use of the same panel occurs. 
         [0042]    It will be appreciated that variations of the insulating base and L-member are possible. For example, the base material may comprise a rebated portion and the L-section arm is coplanar with the outside face of the panel. By the provision of such an arrangement, goods can be placed upon a base prior to erection of walls of the container, with a subsequent erection of the walls by the simple act of inserting them within a channel defined in part by the L-members, without fear of the wall collapsing. This has been found to enable a rapid loading of air-cargo pallets, for example. It will be appreciated that a rapid transfer of product shortens the time that product will not be in a temperature-controlled environment. In a most simple embodiment of the invention, only the base insulating member L-members extending from the outside edges thereof. Notwithstanding this, it is preferred that at least the top portions of the container have panels with the L-members extending from outer edges, whereby to enable the goods to be covered in an equally simple fashion. In the alternative, straps could be placed around the top of the container and around the sides, but many of the advantages of the speed of erecting the containers will be lost. Equally, the corner elements of the sidewall should similarly be protected. 
         [0043]      FIG. 4  shows in some detail how a container in accordance with the invention can be utilised. Container  40  includes four load boxes  41  mounted upon pallets  42 , which are, in turn placed upon base members  22   a ,  22   b  and  22   c , as described above, with trim members  32  around the peripheral edges. The long-side panels  23   a - 23   c  have interlocking features between themselves, conveniently by way of corresponding rebates, whereby to minimise the presence of any gaps therebetween. Panels  23   a  and  23   c  have vertical L-members  32 ; similarly the short-side panels  24   a ,  24   b  interlock with each other and with adjacent panels of the long-sides, the L-member ensuring that there are no gaps between the corners edges between adjacent side wall panels. The upper insulating panels  27   a ,  27   b  and  27   c , as mentioned above are generally similar to the base panels and engage with the upper edges of the side-wall panels, the L-members assisting in maintenance of gap-free edges between the side panels. It will be appreciated that the tongues of a first panel tightly fitting within the rebate defined between an inside wall of a the L-member on one side of the tongue and between an edge portion of the panel on the other side of the tongue 
         [0044]      FIG. 4  also shows cardboard envelopes  28   a  and boxes  28   b  which can retain gel packs, for example, which have a high heat capacity whereby to assist in the maintenance of a particular temperature. The load is contained in boxes  41 , mounted upon pallets  42 . The base, side and top panels may all be manufactured from plastics foam sheets, such as extruded polystyrene or polyurethane. However, in certain circumstances, the panels may comprise expanded polystyrene sheathed with, for example, cardboard, polypropylene sheeting or other types of sheathing. In use, the containers can be disposed of after their first use, due in part to the one-way nature of the cargo involved, be it agricultural produce, say from farms in Africa to Europe or the delivery of pharmaceutical goods. The invention provides a simple to fabricate container which can retain goods reliably within a specific temperature range, achieved, in part, through the use of suitable gel packs filled with substances with a high thermal capacity, together with the inherently low thermal conductivity of the container and the relative air-tightness of the joins between the panels. 
         [0045]      FIG. 5   a  refers to a first variant in that the container is a half LD7 load; there is a single base panel  21   a  and top panel  27   a , with L-members  32  attached to peripheral edges. There are two side panels  22   a ,  22   b  along the long side; the shorter side panels comprise a single element  23   a  which possesses L-members  32  along both vertically oriented edges. The bas panel of the container sits upon a pallet  42 .  FIG. 5   b  shows a still further embodiment: this container varies form the embodiment of  FIG. 5   a  in that the external dimensions are different and that each of the four sides comprise a single side panel. 
         [0046]    The foam panels are conveniently of a laminated construction, whereby, using different densities of foam a lightweight yet stiff structure can be provided. Conveniently these can be provided by commercially available HCFC-free expanded Polyethylene sheet (LDPE), where there is a closed cell structure with extrusion skin. This provides a low water absorption and water-vapour transmission rate. The foam has a high resiliency and flexibility, excellent cushioning behaviour and excellent thermal insulation properties, with a temperature stability of −40 to +70° C. Commercially available foams of such construction are manufactured by companies such as Knauf Insulation Ltd., Sealed Air Inc. etc. It has also been found that when laminated panels of differing density are employed, there is a reduced tendency of the product panels to bow. Through an appropriate choice of materials, lightweight panels can be selected to provide a resilient container which can elastically deform and return to an original position, albeit in a limited fashion. 
         [0047]    Referring now to  FIG. 5   c , there is shown a more detailed view of envelope  28   a , which is attached to an inside face of a side panel. It is typical for refrigerant packs or gel packs (and other types of materials) to be employed as a refrigerant, to maintain a product within a specified temperature range, to maintain a thermal environment in an insulated shipping container sufficient to meet the product&#39;s temperature requirements. A few thermodynamic concepts are involved here: heat transfer, heat absorption, and phase change. These principles are some of the components of the “zeroth law” of thermodynamics. That is, all systems attempt to reach a state in which heat energy is equally distributed. If an object with a higher temperature comes in contact with a lower-temperature object, it will transfer heat to the lower-temperature object. It is to be noted that certain goods must be maintained below ambient temperature; others at above ambient temperature and some at elevated temperature. Such packs have been placed loosely in the container, sometimes within boxes. However, disadvantages arise in that the packs may congregate in a specific area(s), providing an uneven temperature distribution within a container, perhaps damaging product which comes into contact with the gel-packs; the gel-packs or similar may become damaged and rupture, potentially spoiling the contents of a container. The refrigerant envelope can comprise in a simple embodiment a cardboard enclosure, having a rear wall which is attached to a wall of a container, for example by double sided tape—conveniently the same type of tape as employed in the attachment of the L-shaped members. Two open—ended enclosures are defined by the envelope. A first enclosure  51  is for placement of gel-packs  53  and similar objects with a high thermal capacity is located such that, in use, it lies adjacent a container wall  54 ; a second enclosure  52  provides a minimum distance between the gel-packs and the product. Apertures  55  can be provided in a wall of the first enclosure to enable the position of a gel pack within to be determined. Equally, such aperture may assist in allowing convection currents to flow 
         [0048]    The gel-packs comprise units of a solid, being of a generally rectangular shape;  FIG. 5   d  shows how a gel pack  53  can be inserted into a first enclosure of an envelope or pocket  28   a  mounted upon a container wall panel  23   a . Applicants have determined that by reducing the width of the enclosure  51  from the top w 1  to a width w 2 , where w 2  is less than (say 95%) the width of a gel pack w 3 , then the gel packs can be safely inserted into an enclosure without fear of the pack becoming dislodged as a panel is erected (it will be appreciated, since the height of a side panel of a unit load device is frequently of the order of 2 m or more, that the subsequent insertion of a gel pack is ill-advised, since the gel pack could be liable of not being placed properly within its designated place, if any). This could also be of advantage in use of the container, to prevent spillage. The envelope may be placed such that it has a gap between a floor of the container, whereby to assist in the use of convection currents to provide a uniform temperature within the atmosphere of the container.  FIG. 5   e  shows a still further embodiment with an envelope  50  having a solid insulating foam material  57  between the gel pack  51  and product, which, when packaged, will be in close proximity to the envelope unit including spacer  52 ,  57 . Whilst the dimensions of the gel pack can vary, a pack size that has been found to be of a convenient size and weight (3 Kg) is dimensioned 44.7 cm×28.6 cm×3.6 cm. The envelope is conveniently manufactured from corrugated cardboard. Three or more gel packs may be inserted within an envelope. Since it is a commonly used material in the packaging industry and the skills for fabricating and attaching the envelopes are well known. A length of tape may be attached to an upper section of an aperture, in the middle of a face of the aperture; by placing a lower side of a gel pack in contact with the tape, the pack may be lowered in a controlled fashion. A gel pack may have an indentation upon an edge to assist in this procedure, without fear of the gel pack slipping either side of the tape. 
         [0049]    It has been found that using three panels for the top section for the LD7, then the size and weight of the panels is not too great to prevent easy handling of the panels by manual workers. This size of panel e.g. 2×3 m for an LD7 container can be utilised in corresponding pro-rata sizes for smaller Load Device models or, indeed, fewer panels can be employed—what is of particular note is that the modular design of panel size can be utilised for many variants of Load Device container styles. 
         [0050]      FIG. 6  shows an air pallet  60  in plan view. The sizes of these air pallets vary from 1.5×2 m to 2.5 m×4 m. The pallet comprises of a rectangular base, conveniently made from an aluminium alloy. Perimeter extrusions  64 ,  66  are fitted along the major sides, with cast metal (alloy) or moulded plastics corner pieces assisting in maintenance of the integrity of the structure, the extrusions being screw-fastened or riveted to the base plate.  FIG. 6   a  shows the extrusion in plan view;  FIG. 6   b  shows a section through A-A per  FIG. 6   a . Base  60  is clearly visible, as are the fastening means  63 . A corner element connects the two edge extrusion pieces. Both of the figures detail channel  62 , which channel exists around the perimeter to provide locating means for retaining straps (cargo net) and/or for the thermal blanket or sheet. With reference to  FIG. 6   a , the channel  62  has sides which define parallel portions interspersed by short lengths of increased width, whereby feet of a cargo net having a width greater than the channel width of the parallel sections of the channel can be inserted within the channel. 
         [0051]    By the use of foam panels of a low thermal conductivity, little, if any, additional amount of insulation needs to be provided by any boxes within the container: this, in turn, means that there is more effective load space. Equally, the container enables certain goods to be better protected by being individually placed within a container. 
         [0052]    In accordance with a further aspect of the invention, and with reference to  FIGS. 7-11 , the base can integrally combine a pallet base. In the preferred embodiment, shown in perspective views from above, there is a completed container and a container base separated from an otherwise complete container. Two sides  72 ,  73  of the base element  70  are shown, each base element exposing apertures  74  being the openings to channels operable to accept the forks of a fork-lift truck (not shown), whereby to enable the container to be raised—or indeed, just the base be raised, prior to movement to a specific loading or unloading area. These channels  75  are best seen in  FIG. 8 , which shows the underside of a base in perspective view. Equally,  FIG. 11  shows channels  75  defined by the cross-section of a shorter width of the base. 
         [0053]    The base can be made such that a relatively rigid plastics material is utilized with a foam plastics, to provide a rigid body.  FIG. 9  shows the base in an orientation of normal operation. The channel  76  comprising a rebate on the upper surface of the base  70  can be defined in such an outer plastics sheath member, such as glass reinforced plastics or similarly rigid material. Other foam plastics materials could also be employed; for example the base  70  may comprise a foamed plastics of uniform density, in which case separate “L” shape members will be attached and comprise a separate element, formed from mdf, or other appropriate materials, as described with reference to the first-third embodiments. By having the base constructed such that it dispenses with the need of a separate pallet, typically formed from wood, then this removes a problem that is apparent where certain industry sectors require transport containers and ancillary packaging materials to be free from organic products. This is a particular issue with certain pharmaceutical requirement for certain types of load, where integrated with a pallet base and manufactured from a plastics material. 
         [0054]    In a still further variation, the base member may be fixedly associated with the aluminium sheet base  60  as shown in  FIGS. 6-6   b , whereby to enable the effective base area of the container, once constructed, to be increased, whereby to enable a greater volume per unit load device to be achieved. 
         [0055]    The invention provides a simple to fabricate container which can retain goods reliably at a specified temperature due to the use of suitable agents, such as gel packs with high thermal capacities, together with the inherently low thermal conductivity of the container and good levels of sealing between panels. A container in accordance with the present invention may be assembled in a rapid and expeditious manner. The parts making up our box may be stacked for storage in a relatively small space. A distinct benefit of the present invention is that the construction permits different sized boxes to have common parts to provide more cost-effective construction and/or different functionality.