Abstract:
An intermediate insulating product ( 20 ) is disclosed comprising a planar insulating layer ( 11 ) having a top side in to which is formed a plurality of parallel channels ( 14 ) having cross-sections with tapered sides. A vapour proof layer ( 18 ) is applied to the top surface after the channels ( 14 ) have been formed such that the vapour proof layer ( 18 ) bridges the plurality of parallel channels ( 14 ). The intermediate insulating product ( 20 ) is then bent with mechanical manipulation in regions adjacent the bottom of the channels ( 14 ) thereby causing the channels ( 14 ) to close to form a non-planar, derivative insulated ductwork product ( 30 ) and the vapour proof layer ( 18 ) forms a vapour proof inner lining to the derivative insulated ductwork product ( 30 ).

Description:
FIELD OF THE INVENTION  
       [0001]    This invention relates to insulated ductwork products and, in particular, to an intermediate insulating product from which can be formed a derivative insulated ductwork product. 
       BACKGROUND OF THE INVENTION 
       [0002]    Pre-formed insulated ductwork products for carrying gasses in, for example, air conditioning systems and are used throughout the building and construction industry particularly due to their relatively fast speed of erection and relatively low cost compared to metal or plastic pipe work that must be subsequently lagged. An example of such pre-formed insulated ductwork is shown in UK Patent Publication number GB1,137,121 to Lo-Dense Fixings (Rugby) Limited which discloses providing longitudinal channels in a plastics foam material with a backing material which can be folded into a square or a circular cross sectioned insulated ducting. Other examples are shown in U.S. Pat. No. 6,148,867 which also discloses providing longitudinal channels in a fibrous and/or cellular foam insulation material with a moisture facing outer material which can be folded into a circular cross sectioned insulated ducting. Other broadly similar systems are disclosed in International Patent Publication number WO8504922 and Dutch Patent Publication number NL7502320. 
         [0003]    However, such conventional systems suffer from the disadvantage that they cannot be used for ducting liquid as the liquid can ruin the insulating material. Furthermore, the open nature of the insulation material to the airflow passing through the ducting can mean that bugs/diseases etc. are more likely to be able to survive and colonise in the shelter of the insulation joints, thus causing an increased health risk. Moreover, the open nature of the insulation material can also mean that dust from the insulation material could become airborne into the air passing along the throughbore, again causing an increased health risk. 
       BRIEF SUMMARY OF THE INVENTION  
       [0004]    In accordance with a first aspect of the present invention, there is provided an intermediate insulating product comprising a planar insulating layer having a resulting innermost surface in to which is formed a plurality of parallel channels; wherein the channels comprise cross-sections with tapered sides; further comprising a vapour proof layer applied to the resulting innermost surface such that the vapour proof layer bridges the plurality of parallel channels; and wherein, with subsequent mechanical manipulation, the intermediate insulating product can be bent in regions adjacent the bottom of the channels, thereby causing the channels to substantially close to form a non-planar, derivative insulated ductwork product having an inner throughbore and the vapour proof layer forms a vapour proof inner lining to the derivative insulated product; characterised by the vapour proof layer comprising a sealing means to substantially seal the inner throughbore with respect to the outside of the derivative insulated ductwork product. 
         [0005]    The present invention provides a planar intermediate insulating product which can be formed into a non-planar, derivative insulated ductwork product. The derivative insulated ductwork product is typically of sufficient strength such that it can be installed to provide a fluid conduit such as an air conditioning conduit of itself and thereby obviates the time consuming and expensive conventional requirement for metal ductwork to be applied with insulation such as that shown in U.S. Pat. No. 6,000,437. 
         [0006]    Importantly, the taper enables up to the substantial entirety of the sides of the channels (as existing in the intermediate insulating product) to contact each other when formed into the derivative insulated product, thereby ensuring integrity of the insulation in the derivative insulation product. 
         [0007]    Typically, a continuous protective layer is provided on the bottom side of the insulating layer. 
         [0008]    Typically, a protective layer is provided on the top side of the planar insulating layer prior to forming the channels, said protective layer adapted to reduce flaking or chipping of the planar insulating layer. 
         [0009]    The channels are preferably formed by routing and optionally, the channels may be at least partially filled with a sealant and/or an adhesive. 
         [0010]    The cumulative internal angles of the channels are typically arranged such that it is possible to bend the intermediate insulating product so as to form the derivative insulated ductwork product with a complete polygon cross-section. 
         [0011]    Preferably, the sealing means comprises a flap member provided at one end of the vapour proof layer and which is arranged to overlap the other end of the vapour proof layer when the intermediate insulating product has been bent to form the non-planar, derivative insulated product such that the vapour proof layer extends greater than 360 degrees around the inner throughbore. Moreover, the vapour proof layer is preferably substantially the same width as the resulting innermost surface of the planar insulating layer to which it is applied, and has a longer length than the resulting innermost surface of the planar insulating layer such that the flap member projects past one end of the planar insulating layer. Typically, the flap member is integral with and forms an extension of the rest of the vapour proof layer. 
         [0012]    The vapour proof layer preferably comprises a laminated vapour proof barrier and more preferably comprises a laminated foil vapour proof barrier formed from a number of layered sheets. 
         [0013]    Typically, the vapour proof layer comprises a securing means formed on it&#39;s resulting outermost surface and which is adapted to secure the vapour proof layer to the said resulting innermost surface of the planar insulating layer. Preferably, the securing means comprises a self adhesive formed on the resulting innermost surface of the vapour proof layer and more preferably the self adhesive comprises a pressure sensitive adhesive pre-applied to the resulting outermost surface of the vapour proof layer. 
         [0014]    Preferably, a further vapour proof layer is applied to the bottom surface of the planar insulating layer such that the said further vapour proof layer forms an outer vapour proof protective barrier to the derivative insulated product. Preferably, a further securing means is provided between the further vapour proof layer and the said bottom surface, and the said further securing means preferably comprises an adhesive means initially provided on the inner most surface of the further vapour proof layer. 
         [0015]    The planar insulating layer comprises a substantially rigid material, and more preferably comprises a rigid phenolic foam. 
         [0016]    According to a second aspect of the present invention there is also provided a derivative insulated ductwork product formed from an intermediate insulating product according to the first aspect of the present invention by mechanical manipulation of the intermediate insulating product thereof to bend it in regions adjacent the bottom of the channels, thereby causing the channels to close to form the non-planar, derivative insulated ductwork product. 
         [0017]    Typically, a complete polygon cross-section is formed from an intermediate insulating product with cumulative internal angles of the channels such that it was possible to bend the intermediate insulating product so as to form a complete polygonal cross-section. 
         [0018]    Preferably, the derivative insulated ductwork product is secured along a joining edge by a strip of adhesive tape applied along the joining edges of what was the intermediate insulation product. 
         [0019]    According to a third aspect of the present invention there is also provided a section of ductwork product formed from an intermediate insulating product according to the first aspect of the present invention by mechanical manipulation of the intermediate insulating product thereof to bend it in regions adjacent the bottom of the channels, thereby causing the channels to close to form the non-planar, derivative insulated ductwork product. 
         [0020]    According to a fourth aspect of the present invention there is also provided a connecting means for connecting a first section of ductwork in accordance with the third aspect of the present invention to a second section of ductwork in accordance with the third aspect of the present invention, the connecting means comprising:
       a first fitting member having an open end for accepting an end of the first section of ductwork;   wherein the other end of the first fitting member is connected to a side of a flange member which projects outwardly from the first fitting member; and   a second fitting member having an open end for accepting an end of the second section of ductwork; wherein   the other end of the second fitting member is connected to a side of a flange member which projects outwardly from the second fitting member;   and an internal throughbore which provides a sealed passageway for fluid to travel from a throughbore of the first ductwork, through said internal throughbore and into a throughbore of the second ductwork.       
 
         [0026]    According to a fifth aspect of the present invention there is also provided a ductwork system comprising two or more sections of ductwork in accordance with the third aspect of the present invention and one or more connecting devices, the connecting devices comprising:
       a first fitting member having an open end for accepting an end of the first section of ductwork;   wherein the other end of the first fitting member is connected to a side of a first flange member which projects outwardly from the first fitting member; and   a second fitting member having an open end for accepting an end of the second section of ductwork; wherein   the other end of the second fitting member is connected to a side of a second flange member which projects outwardly from the second fitting member;   and an internal throughbore which provides a sealed passageway for fluid to travel from a throughbore of the first ductwork, through said internal throughbore and into a throughbore of the second ductwork.       
 
         [0032]    Preferably, the first and second fitting members comprise respective first and second annular rings. 
         [0033]    Typically, the first and second annular rings each comprise a substantially constant inner diameter and a substantially constant outer diameter. 
         [0034]    Preferably, the said flange member(s) project radially outwardly from the respective first and second fitting members. 
         [0035]    The outer diameter of the respective first and second fitting member preferably contacts the inner diameter of the respective ductwork and the said one face of the flange member is arranged into butting contact with the end of the respective ductwork. 
         [0036]    The first and second fitting members preferably further comprise a securing means which acts between the fitting members and the respective ductwork to prevent separation of the ductwork from the fitting member in a direction away from the flange member. 
         [0037]    The securing means preferably comprise one or more barb member(s) which point in a direction toward the respective flange member. 
         [0038]    The first and second fitting members may each comprise the same outer diameter. Alternatively, the first and second fitting members may each comprise different outer diameters. 
         [0039]    Preferably, the flange member projects outwardly from the first and second fitting member by a distance substantially equal to the sidewall thickness of the ducting. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0040]      FIGS. 1A to 1F  are sections illustrating the formation of a derivate insulated product from an intermediate insulation product, in accordance with the first, second and third aspects of the present invention; 
           [0041]      FIGS. 2A and 2B  are sections illustrating alternative channel cross-sections of an intermediate insulation product in accordance with the first, second and third aspects of the present invention; and 
           [0042]      FIG. 3A  is a side view of a connector in accordance with a fourth aspect of the present invention for connecting two derivative insulated ductwork products in accordance with the first, second and third aspects of the present invention where both ductworks have the same internal diameter; 
           [0043]      FIG. 3B  is a cross sectional side view through one half of the connector of  FIG. 3A ; 
           [0044]      FIG. 3C  is a perspective view of the connector at  FIG. 3A ; 
           [0045]      FIG. 4A  is a side view of another embodiment of a connector in accordance with the fourth aspect of the present invention for connecting two ductworks having the same internal diameter together but at a 45° angle to one another in order to create a 45° bend; 
           [0046]      FIG. 4B  is a perspective view of the connector at  FIG. 4A ; 
           [0047]      FIG. 5A  is a side view of another embodiment of a connector in accordance with the fourth aspect of the present invention for connecting two ductworks having the same internal diameter together but at a 30° angle to one another in order to create a 30° bend; 
           [0048]      FIG. 5B  is a perspective view of the connector at  FIG. 5A ; 
           [0049]      FIG. 6A  is a side view of a connector in accordance with the fourth aspect of the present invention for connecting one ductwork having a larger internal diameter to another ductwork having a smaller internal diameter; 
           [0050]      FIG. 6B  is a cross sectional view through the lower half of the connector at  FIG. 6A ; 
           [0051]      FIG. 6C  is a side view of a slightly different embodiment of the connector shown in  FIG. 6A ; 
           [0052]      FIG. 6D  is a first perspective side view of the connector shown in  FIG. 6C ; 
           [0053]      FIG. 6E  is another perspective side view of the connector shown in  FIG. 6C ; 
           [0054]      FIG. 7A  is a side view of a connector in accordance with the fourth aspect of the present invention to break into a square section of ductwork to provide a branch of another section of ductwork; 
           [0055]      FIG. 7B  is an end view of the connector shown in  FIG. 7A ; 
           [0056]      FIG. 8A  is another embodiment of a connector in accordance with a fourth aspect of the present invention for connecting a relatively large circular ductwork to a relatively small diameter circular ductwork; 
           [0057]      FIG. 8B  is a perspective view of the connector shown in  FIG. 8A ; and 
           [0058]      FIG. 9  is a side view of a connector in accordance with the fourth aspect of the present invention to break into a circular section of ductwork to provide a branch of another section of ductwork. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0059]      FIG. 1A  is a section through a planar slab of insulating product  10 . The product  10  has a “sandwich” construction with a core  11  of rigid phenolic insulating foam having a topside protective layer  12  and a bottomside protective layer  13 , both layers  12  and  13  being in the form of an aluminum foil or fibre glass scrim layer  12 ,  13 . Such a product  10  may be commercially sourced, for example, such foam slabs are, at the time of writing, available from Kingspan Insulation Limited of Herefordshire in the UK in standard sizes of 1200 mm×2950 mm and 1000 mm×2950 mm and are typically either 22 mm or 33 mm thick. Alternative core insulating material  11  could also be used such as a polyisocyanurate or a polyurethane. 
         [0060]    Referring to  FIG. 1B , the planer slab  10  is formed into an intermediate insulation product  20  according to the first aspect of the present invention by firstly providing the slab  10  with a series of parallel, “V” shaped channels  14  formed therein and with the edges of slab chamfered  15 ,  15 ′ at the same angle as the sides of the channels  14 . 
         [0061]    Such channels  14  and chamfers  15 ,  15 ′ may be formed in the slab  10  by a CNC router with a V shaped router bit. Where this is the case, the protective layer of material  12  may offer some protection to the core  11  against chipping or flaking during the routing, especially where the core  11  is made of a brittle insulator. 
         [0062]    The cumulative sums of the internal angles of the all channels and the angle subtended between both chamfers  15 ,  15 , is approximately 360°. 
         [0063]      FIG. 1B  shows the intermediate insulation product  20  with optional adhesive sealant  16  deposited in the bases of the channels  14 . 
         [0064]    The next step in forming an intermediate insulating product in accordance with the first aspect of the present invention is to apply a vapour barrier  18 , having a securing means in the form of self adhesive  18 A provided on its underside, to the upper and interrupted surface of the product  10  such that the adhesive  18 A secures the vapour barrier  18  to the upper surface  12  of the core  11  such that the vapour barrier  18  spans across all of the channels  14 . The vapour barrier  18  is preferably a laminated foil vapour barrier  18  and the adhesive  18 A is preferably a pressure sensitive adhesive, which is pre-applied to the underside of the laminated foil barrier  18 . Such a self-adhesive vapour barrier  18  can be commercially sourced. For example, the preferred vapour barrier  18  is a five ply laminated aluminum foil vapour barrier available from Venture Tape® of Northants, UK sold under the trade name VentureClad 1577CW®. Alternative vapour barriers could also be used such as polythene and a suitable example of such a polythene is Duponts&#39; chlorosulfonated polyethylene products marketed as Hypalon®. 
         [0065]    Optionally, where the ductwork  30  is to be used in external applications (e.g. on the outside of buildings, factories, oil rigs etc.), a further outer layer (not shown) is preferably attached to the bottomside on the outer surface of the aluminum foil surface  13 . Preferably, such a further outer layer is also vapour proof to enable the ductwork  30  to be weather proof. The vapour outer layer is preferably again a laminated foil vapour barrier provided with a pre-applied pressure sensitive adhesive and such a self-adhesive vapour barrier can be commercially sourced and is more preferably a five ply laminated aluminum foil vapour barrier available from Venture Tape® of Northants, UK sold under the trade name VentureClad 1577CW®. 
         [0066]    This results in the formation of the intermediate insulating product  20 . 
         [0067]    Thereafter and as illustrated in  FIGS. 1D ,  1 E and  1 F, the intermediate insulation product  20  (with optional adhesive sealant  16 ) may be rolled up with appropriate mechanical manipulation or by hand whereupon the continuous areas  17  of core  11  deform, enabling the channels  14  to close and a polygonal shaped insulated product  30  to be formed as shown in  FIG. 1E . Thus, a derivative insulated product  30  is then formed which can be used as a ductwork  30  to carry fluid such as air in for example an air conditioning system for a building. 
         [0068]    The adhesive sealant  16  if present ensures a tight and permanent seal between the edges of the channels  14 . Surplus adhesive sealant if present, egresses from the closed channels  14  and solidifies at the internal edge of the join between the channels  14 . 
         [0069]    Moreover, and as can be best seen in  FIG. 1F , when the intermediate insulating product  20  with vapour barrier  18  attached is rolled up, the section of the inner lining  18 C which bridges the channels  14  will naturally be moved into the channels  14  and thereby form a seal over the channels  14 . The width of the vapour barrier  18  typically equals the width of the intermediate insulating product  20  although as can be seen in  FIG. 1C  the length of the vapour barrier  18  is greater than the length of the intermediate insulating product  20  such that a flap member  18 ′ is provided at one end of the intermediate insulating product  20 . Furthermore, when the intermediate insulating product  20  has been fully rolled up to form the ductwork  30 , the entire inner throughbore  40  of the ductwork  30  can be sealed with respect to the outside of the ductwork  30  by pressing the inner lining flap  18 ′ (as seen in  FIG. 1C  as being provided at one end of the vapour barrier  18 ) with a suitable smooth edged hand tool or machine tool to seal the flap  18 ′ against the other end of the vapour barrier  18 . Accordingly, the flap  18 ′ (which is integral with the rest of the vapour barrier  18 ) provides an overlap with the other end of the vapour barrier  18  when the intermediate insulating product has been bent to form the ductwork  30  such that the vapour barrier  18  extends greater than 360 degrees around the inner throughbore. 
         [0070]    Consequently, the ductwork  30  can be used to carry liquids and/or provides a sealed throughbore  40  such that the risk of any air born bugs/diseases finding shelter to grow is substantially reduced. 
         [0071]    Alternatively, and/or additionally, the vapour barrier  18  can be provided with a self cleaning and/or anti-bacterial surface coating and such a surface coating is commercially available from Cytack UK Limited and/or the vapour barrier  18  can be formed of a vinyl base with such an anti-bacterial and/or self cleaning layer applied. 
         [0072]    Alternatively and preferably, the vapour barrier  18  may be pressed into the channels  14  (when it is applied to the upper surface of the planer product  10  to form the intermediate product  20 ) by a suitable tool such as a “V” shaped smooth edged hand tool (not shown) such that in the region of 5 mm of vapour barrier  18  is stuck to each channel  14 . 
         [0073]    The longitudinal edges of the intermediate insulation product  20  which have been pushed together are held in place by an adhesive strip  19  of laminated foil vapour barrier. Ideally, this strip  19  is the same material as the laminated foil vapour barrier  13  already applied to the underside of the core slab  10  as illustrated in  FIG. 1A  and now on the periphery of the formed polygon shaped derivative insulated product or ductwork  30  as illustrated in  FIG. 1E . 
         [0074]    Optionally and additionally bands such as bands of tape or aluminum or plastic bands could be provided around the outer circumference of the derivative insulting product/ductwork  30  to provide additional strength in order to keep the edges (of the intermediate insulation product  20 ) together and thereby the polygon shape of the ductwork  30 . 
         [0075]    The channels are shown in  FIGS. 1A to 1C  as perfect V shaped channels. However, embodiments of the present invention are much more preferably provided with the alternative channel cross-sections illustrated in  FIGS. 2A and 2B . In  FIG. 2A , the base of a channel  14  is shown with a small, flat section  120  and in  FIG. 2B , it is curved  121 . Also, the depth of the channels  14  could be varied depending on the strength of the insulating product core  11  and/or the thickness of the material and/or the elasticity of the bottomside protective layer  13  should it need to expand to accommodate deformation for the insulating product core  11 . Conceivably, the base of the channel  14  could extend to the bottomside protective layer  13  where there would then be no deformation of the insulating core  11  as such, just flexing of the supporting bottomside protective layer  13 . 
         [0076]    In the above example, it is stated that the cumulative sums of the internal angles of the channels  14  and the angle subtended between both chamfers  15 ,  15 ′ is approximately 360®. However, because the adhesive sealant  18  may partially fill the channel  14  such that the edges of the channel do not fully meet, a complete and structurally sound polygon  30  can be created when the cumulative sum of angles of the channels  14  and the angle subtended between both chamfers  15 ,  15 ′ exceeds 360° 
         [0077]    Conversely, the edges of the channels  14 , may deform when pushed together, enabling a complete polygon  30  to be created when the cumulative sum of angles of the channels  14  and the angle subtended between both chamfers  15 ,  15 ′ is less than 360°. 
         [0078]    In the above example, the taper of the channels  14  is uniform. This need not be the case and indeed appropriate selection of tapers could be used, for example, to provide a polygon shaped derivative insulated ducting product  30  with a degree of eccentricity (e.g. approximating an ellipse). For example, the resulting insulating product/ductwork  30  need not be circular but could be, for example, an oval shape having flattened sides to provide a flat oval ductwork (not shown) by leaving the upper and lower flat sections of the ductwork  30  without channels  14 . 
         [0079]    Also in the above example, the insulating core  11  is shown with two initial protective layers  12 ,  13 . However, the principle of the present invention applies equally to insulator cores  11  with a single protective layer  13  or indeed no protective layer. 
         [0080]    Furthermore, whilst the shape of the derivative insulated product  30  described is polygonal, the more channels  14  use to form a polygon, the more it will approximate a circle, especially if the deformation of the core  11  at the base  17  of the channel  14  smoothes the periphery of the polygon. 
         [0081]    Typically, the ductwork  30  would be supplied to its site of installation (e.g. a building site) from a factory pre-rolled and as shown in  FIG. 1E  such that it is ready to be installed on site. In order to aid installation on site and also to ensure that individual ductwork  30  sections can be joined together in a sealed manner, a number of connectors in accordance with the fourth aspect of the present invention are also provided and are shown in  FIGS. 3-8 . 
         [0082]    The first embodiment of a connector  200  is shown in  FIGS. 3A ,  3 B and  3 C. The connector  200  comprises an annular ring  210  having a constant inner diameter and being provided with an outwardly extending flange shoulder  220  which projects radially outwardly from the mid point of the annular ring  210 . An outwardly and rearwardly projecting gripping means in the form of a pointed rib or barb  230 L,  230 R is also provided on each side of the flange ring  220  where the barb  230 L,  230 R has a sharpened outer point which is pointed in the direction of the flange ring  220 . The connector  200  is preferably formed of a rigid plastic material such as a Class O (fire resistant) plastic material but it could be formed from other suitable materials and this could be a metal such as galvanised sheet, aluminum sheet, stainless steel, aluminised steel etc., depending upon the end use of the ductwork  30 . 
         [0083]    In use, a left hand section of ductwork  30  is pushed on to the left hand part  210 L of the annular ring  210  where the outer diameter of the annular ring  210  is chosen such that it is a close fit with the inner diameter of the ductwork  30 . The ductwork  30  is pushed on to the connector  200  until the end of the ductwork  30  butts against the left hand face of the flange should  220  and the barb  230 L projects into and thereby grips the inner diameter of the ductwork  30 . The angle of the barb  230 L is such that it prevents the ductwork  30  from backing off the connector  200 . An end of an other ductwork  30  is pushed on to the other end  210 R of the connector  200  and the radius of the flange  220  is chosen such that it has the same diameter as the outer surface of both sections of ductwork  30  such that a flushed outer joint is provided between the two ends of the ductworks  30  and the flange  220 . A suitable adhesive, such as a mastic, can be applied between the connector  200  and the inner circumference of the ductwork  30  if desired, in order to increase the connection between the two. The two ductworks  30  can then be sealed together by applying tape around the outer circumference of the joint such that the tape seals over the joint created between the flange  220  and the two ends of the ductwork  30 . 
         [0084]    The ductwork  30  can be cut on site to suit the length required. 
         [0085]    Various other connectors are shown in the drawings.  FIG. 4A  shows a connector broadly similar to the connector  200  but formed with a  45 ° bend between the left hand  310 L and right hand  310 R sides of the annular ring  310 . Bards  330 L and  330 R are also provided and point towards the flange ring  320  and serve the same purpose as the barbs  230 L,  230 R and flange ring  220  as described for the connector  200 . Moreover, two connectors  300  can be used with a short length of ducting  30  there between to form a 90° bend in a long length of duct tape  30 . 
         [0086]      FIG. 5A  shows another embodiment of connector which is broadly similar to the connector  300  of  FIGS. 4A  and B where like components in the connector  500  have been indicated with a numeral prefix  5  instead of numeral pre-fix  3 . The main difference between the connector  300  and  500  is that the connector  500  has a 30° angle between the two sides  510 L and  510 R and thus three connectors  500  could be used together with short lengths of ductwork  30  between them in order to make a 90° bend in a long length of a plurality of ductwork sections  30  connected in series. 
         [0087]      FIGS. 6A and 6B  show a broadly similar connector  600  to the connector  200  of  FIG. 3A to 3C  where like components have been marked with the reference numeral prefix  6  instead of the reference numeral prefix  2 . 
         [0088]    However, there is a difference in the connector  600  in that the right hand side annual ring  610  R is smaller in diameter than the left hand side annular  61 OR in order that the connector  600  can be used to connect two ductworks  30  having different diameters together. 
         [0089]      FIGS. 6C ,  6 D and  6 E show a very similar connector  600  to that of  FIGS. 6A and 6B  where the only difference between them is that the connector  600  in  FIGS. 6C and 6E  has two barbs  630 L and  630 L′ on the left hand annular ring  610 L and also has two barbs  630 R,  630 R′ on the right hand annular ring  61 OR in order to increase the gripping force between the connector  600  and the ductworks  30 . 
         [0090]    The connector  800  shown in  FIG. 8A  is broadly similar to the connector  700  and like components have the prefix  8  instead of the prefix  7 . However, the connector  800  has a circular cross section at each end  810 L and  81 OR but which are again separated by a tapered transitional diameter section  810 M. 
         [0091]    The connector  900  in  FIG. 9  is somewhat different from the other connectors in that the left hand side  910 L comprises a concave end face and is intended to be inserted into an aperture cut into the side wall of a length of circular ductwork  30  such that the end  910 L provides the ability to cut into longitudinal lengths of circular ductwork  30 .  FIGS. 7A and 7B  show another form of connector  700  which is broadly similar to the connector  900  shown in  FIG. 9  where like components have the prefix  7  instead of the prefix  9 . However, the connector  700  has a left hand annular ring  710 L which has a flat end face and is oval in cross section, and the right hand side of the flange ring  720 L is connected to a tapered transitional diameter section  710 M which reduces in diameter from the left hand to the right hand side until it joins the left hand side of the flange ring  720 R. The flat end face of the left hand annular ring  710 L is arranged to be inserted into a like-shaped aperture cut into the planar sidewall of a rectangular section of ductwork  30 . 
         [0092]    In all cases, tape is wound around the joints created by the connectors such that the connectors are sealed with respect to the ductwork lengths  30 , and a preferred tape will match the external coating of the ductwork  30 . For example, if the ductwork  30  is supplied with the additional vapour proof outer layer, the tape  18  can comprise the same material as the additional layer (since it is preferably self adhesive). However, if the ductwork  30  is supplied without the additional vapour proof outer layer, the tape  18  can comprise any other suitable tape such as reinforced Aluminum foil tape available from Kingspan Insulation Limited of Herefordshire in the UK under product number 1524. 
         [0093]    Modifications and improvements to the embodiments of the present inventions described herein may be made by those persons skilled in the relevant art without departing from the scope of the invention.