Abstract:
A line conduit ( 10 ) to be cast into a structural element ( 12 ), especially a floor/ceiling and/or wall made of concrete, including an elongated housing ( 18 ) that has a holding space ( 25 ) for at least one line ( 16 ). The space is continuous in the lengthwise direction (L), and includes a fire-protection element ( 26 ) made of an intumescent material that is arranged around the inner wall of the housing ( 18 ) in the circumferential direction, whereby at least one anchoring element ( 34 ) is provided on the inner wall of the housing ( 18 ), the element being anchored inside the fire-protection element ( 26 ).

Description:
[0001]    The invention relates to a line conduit to be cast into a structural element, especially a floor/ceiling or wall made of concrete, comprising an elongated housing that has a holding space for at least one line, said space being continuous in the lengthwise direction, and comprising a fire-protection element made of an intumescent material that is arranged around the inner wall of the housing in the circumferential direction. 
       BACKGROUND 
       [0002]    Line conduits are employed when structural elements are built using concrete or another liquid construction material so that openings in floors/ceilings or walls for lines such as, for instance, cables or pipes can be kept free in the structural elements or else can be integrated in them. The line conduits are positioned in a mold (formwork) into which the liquid construction material is filled, and they keep the desired opening in the structural element free while the construction material is being filled in. 
         [0003]    The line conduits can also be removed once the construction material has hardened. However, they are often left in the wall and additional elements, for example, seals or fire-protection elements, are arranged in them so that the wall or floor/ceiling can be closed in case of a fire. The fire-protection element can be made of an intumescent material whose volume expands under exposure to heat, thus closing the wall opening. 
         [0004]    The fire-protection element can be positioned in such a way that, once the wall or floor/ceiling is finished, it is situated on the surface of the structural element. As a result, the presence of heat will quickly heat up and activate the intumescent material. 
         [0005]    This is particularly advantageous for a floor/ceiling opening. Plastic tubes that pass through such a floor/ceiling soften very quickly upon exposure to heat, forming a drop-shaped constriction below the insulating fire-protection element. The remaining, soft plastic tube is compressed and sealed off by the expanding fire-protection element. The tube that remains below the fire-protection element continues to melt or drops off due to gravity, while the fire-protection element, which continues to expand, is pressed into the section that remains in the line conduit. 
         [0006]    This creates a stable bond between the remaining line section and the intumescent material. This entails the advantage that the fire-protection element is affixed and stabilized in the line conduit by the line section. Therefore, after the conduit has been heated up and sealed, there is sufficient stability to withstand, for example, a jet of water that is aimed directly at the fire-protection element. 
         [0007]    In order to achieve a smooth wall finish, the fire-protection element is often arranged not on but rather in the opening in the wall or the floor/ceiling, so that the fire-protection element does not project beyond the surface of the structural element. This has the advantage that such a fire-protection element can be cast into the structural element while it is being made. 
       SUMMARY OF THE INVENTION 
       [0008]    A drawback of this arrangement of the fire-protection element, however, is that the fire-protection element is only activated at a later point in time since the structural element keeps the heat away from the fire-protection element for a longer period of time. Consequently, the plastic tube is already completely melted in this area and the expanding intumescent material cannot bond to the plastic tube. As a result, the plastic tube can no longer support the expanded fire-protection element, so that the resistance of the intumescent material against a jet of water or other forces might be diminished. In order to provide greater stability, the fire-protection elements of such line conduits have to be dimensioned larger. 
         [0009]    An object of the present invention is to provide a compact line conduit that has a fire-protection element having an intumescent material arranged in the housing and that provides sufficient stability of the fire-protection element in the line conduit, even after the intumescent material is in its expanded state. 
         [0010]    The present invention provides a line conduit provided to be cast into a structural element, especially a floor/ceiling or wall made of concrete, comprising an elongated housing with a holding space for at least one line, said space being continuous in the lengthwise direction, and comprising a fire-protection element made of an intumescent material that is arranged around the inner wall of the housing in the circumferential direction. According to the invention, at least one anchoring element is provided on the inner wall of the housing, said element being anchored inside the fire-protection element. In case of a fire, the intumescent material forms a microporous and heat-insulating foam layer that, thanks to its low thermal conductivity and the exclusion of oxygen, protects the lines against the effects of the fire. 
         [0011]    In the prior-art line conduits, the fire-protection element is merely placed on the inside of the elongated housing in order to allow said element to expand radially inwards without encountering any resistance, so that it can seal off the holding space. Even though the fire-protection element is often arranged in a groove in the elongated housing, it has no other permanent connection to the housing, so that, after the intumescent material has expanded, it can be pushed out of the line conduit without offering much resistance. 
         [0012]    The anchoring element provided according to the invention ensures that, even after the intumescent material has expanded, a stable form-fitting connection exists between the housing and the fire-protection element in order to prevent the fire-protection element from being pushed out of the line conduit. The anchoring element securely holds the fire-protection element in the housing of the line conduit, even after the intumescent material has expanded, thereby ensuring that the wall or floor/ceiling opening is reliably closed, even in the case of exposure to substantial forces such as, for instance, the impact of a jet of water. 
         [0013]    The anchoring element can be configured, for example, in such a way that it is surrounded on both sides by the intumescent material, as seen in the radial direction of the housing. As the intumescent material expands, the anchoring element is pressed by the fire-protection element—especially by the section of the fire-protection element that is radially on the outside—radially inwards into the conduit, as a result of which the holding function of the anchoring element can be enhanced. 
         [0014]    The anchoring element is arranged, at least in certain sections, for example, in the lengthwise direction of the housing, so that it does not protrude inwards in the non-activated state of the intumescent material. When the intumescent material expands, the intumescent material that is between the wall opening and the anchoring element presses the anchoring element inwards into the holding space, so that the holding function can be enhanced. In particular, the anchoring element is arranged with one free end in the lengthwise direction of the housing, as a result of which the anchoring element can be simply bent radially inwards with this end. 
         [0015]    The housing can have two sections with an essentially constant cross section, whereby the fire-protection element is arranged between these sections. The two sections define the diameter of the holding space and thus the cross section that is kept free for the lines. The fire-protection element is arranged between these, so that said element is in the center of the structural element and does not project to either side of the wall or floor/ceiling. 
         [0016]    The anchoring element can project from the first or second section, for example, in the lengthwise direction, and can extend into the fire-protection element. In particular, the anchoring element can be part of this section. Thus, the axial end of the appertaining section can extend into the fire-protection element and can be, for example, slipped onto it, which translates into a simple construction of the line conduit. The line conduit can be configured, for instance, in modular form, so that an adaptation to the thickness of the wall or of the floor/ceiling or to the desired position of the fire-protection element is possible on site by changing the sections. The selected sections are plugged onto or inserted into the fire-protection element just before the wall or the floor/ceiling is built. 
         [0017]    Preferably, a holding section in which the fire-protection element is accommodated is provided between the two sections. This holding section is preferably configured in such a way that it is situated between the structural element and the fire-protection element. In this manner, the fire-protection element is reliably protected against the liquid construction material when the wall or the floor/ceiling is being built. Together with the housing sections, the holding section can form a stable wall which prevents the fire-protection element from being compressed by the pressure exerted by the flowable material. In particular, this holding section is made of metal, thus allowing a quick transmission of heat from the structural element to the fire-protection element, so that the latter can be activated more quickly and can expand in case of fire. 
         [0018]    The housing widens perpendicular to the lengthwise direction, for example, in the area of the holding section, so that an encircling groove is formed in the circumferential direction, and the fire-protection element is arranged in this groove. The fire-protection element can be arranged in this holding section in such a way that it does not project beyond the two sections, as seen in the lengthwise direction of the housing. Therefore, the fire-protection element cannot be damaged when a line is inserted into it. 
         [0019]    The housing is configured, for example, so as to be cylindrical, thus forming an ideal conduit for a pipe or a round line. Moreover, the pressure resistance of a cylinder to the liquid concrete or to another construction material is excellent, thus reliably ruling out any compression of the line conduit when the structural element is being cast. 
         [0020]    A flange that projects radially can be provided on the first and/or second section of the housing and can be employed in a formwork used for the structural element, for example, to fasten or seal off the line conduit. Moreover, this flange constitutes a more stable connection between the structural element and the line conduit. The flange can rest on the surface of the finished structural element or else it can be flush with it. If applicable, the flange and thus the line conduit can be anchored in the structural element by means of additional fastening elements or else they can be attached to these additional elements. 
         [0021]    A flange only allows the attachment or sealing off of the line conduit on a flat substrate on which the flange can rest so as to cover the entire surface. For purposes of attaching the line conduit to differing substrates, other fastening devices can also be provided on the first and/or second section. 
         [0022]    The line conduit is normally placed onto the formwork in such a way that it seals tightly against the formwork and no flowable construction material can penetrate into the holding space. The housing can also have closure elements with which the holding space is closed in the lengthwise direction so that there is additional protection against penetration by the construction material into the holding space when the structural element is being built. These closure elements can be removed, for example, together with the formwork, after the structural element has been built, so that the holding space is freely accessible. 
         [0023]    The anchoring element can be made, for instance, of metal, thus allowing a quick transmission of heat to the fire-protection element. However, it is likewise possible for the anchoring element to be at least partially made of plastic, which facilitates the shaping of the anchoring element. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]    Additional advantages and features can be found in the description below in conjunction with the accompanying drawings. These show the following: 
           [0025]      FIG. 1  a line conduit according to the invention; 
           [0026]      FIG. 2  a detailed view of the fire-protection element of the line conduit as shown in  FIG. 1 ; 
           [0027]      FIG. 3  a mold for building the structural element with the line conduit as shown in  FIG. 1 ; 
           [0028]      FIG. 4  a structural element with the line conduit as shown in  FIG. 1 ; and 
           [0029]      FIG. 5  the structural element from  FIG. 4  after a fire test has been carried out. 
       
    
    
     DETAILED DESCRIPTION 
       [0030]      FIG. 1  shows a line conduit  10  for a structural element  12  (see  FIGS. 4 and 5 ). During or after the building of the structural element  12 , which is cast using a liquid construction material, for example, concrete, the line conduit  10  serves to keep a passage  14  free through which a line  16 , for instance, a cable or a pipe, can pass. Another function of the line conduit  10  is to seal the passage  14  in order to prevent penetration by smoke or flames through the passage  14  in case of a fire. 
         [0031]    The line conduit  10  comprises a housing  18  having an essentially cylindrical shape. The housing  18  has a first section  20  as well as a second section  22 , whereby the cross section of both sections  20 ,  22  is essentially the same. A holding section  24  is provided between the sections  20 ,  22  and it forms a groove-like, circumferential widened portion of the housing  18  between the sections  20 ,  22 . Together with the holding section  24 , the sections  20 ,  22  define a holding space  25  for the line  16 . 
         [0032]    The holding section  24  has an essentially U-shaped cross section in which a fire-protection element  26  made of an intumescent material is accommodated. Upon exposure to heat, the protection element  26  increases in terms of its volume so that the passage  14  in the structural element  12  or the holding space  25  is sealed and the propagation of smoke or flames is prevented. The sections  20 ,  22  are each in contact with a leg of this U so that the holding section  24  forms a groove or depression in the holding space  25  that is oriented radially outwards. 
         [0033]    On the first section  20 , there is a radially projecting flange  28  that serves to attach and seal the line conduit  10  to a mold  30 , for example, formwork for concrete, into which the structural element  12  can be cast (also see  FIG. 3 ). Moreover, this flange  28  accounts for better fixation of the line conduit  10  in the finished structural element  12 . 
         [0034]    The second section  22  has a closure element  32  that can be removed after the structural element  12  has been made. The closure element  32  closes off the holding space  25  and protects it against the liquid construction material that could flow into the holding space  25  when the structural element  12  is being built. 
         [0035]    Moreover, on the second section  22 , there is an anchoring element  34  that extends in the lengthwise direction L of the housing  18  into the holding section  24  and thus into the fire-protection element  26 , or else the anchoring element  34  is anchored in the fire-protection element  26 . In the embodiment shown here, the anchoring element  34  is formed by a part or an extension of the second section  22  that extends all the way into the fire-protection element  26 . However, it is possible for the anchoring element  34  to be a separate component that is provided on one of the sections  20 ,  22  or on the holding section  24 . 
         [0036]    As can be seen in  FIG. 2 , the anchoring element  34  is covered by the fire-protection element  26 , in other words, by the intumescent material, on the radial outside  36  as well as on the radial inside  38 . 
         [0037]    Before the structural element  12  is made, the line conduit  10  is positioned in a mold  30  ( FIG. 3 ) and affixed in it. The length d of the line conduit  10  is selected in such a way that it is equal to or greater than the thickness D of the structural element  12 , so that the passage  14  can be kept completely free. 
         [0038]    Subsequently, the liquid construction material, for instance, concrete, is poured into the mold  30 . After the construction material has hardened, the mold  30  is removed, whereby the positioning elements that had been provided on the mold  30  or on the line conduit in order to affix the position in the mold can also be removed during this step. Subsequently, the closure element  32  can be removed and a line  16  can be laid through the line conduit  10  ( FIG. 4 ). 
         [0039]    If the structural element  12  is exposed to strong heat, for example, because of a fire, this causes the line  16  to melt in this area, so that a constriction is formed owing to the intrinsic weight of the line  16 . At the same time, the generation of strong heat activates the fire-protection element  26 , which then expands so that the passage  14  is closed off by the fire-protection element  26  ( FIG. 5 ). In this process, the remaining soft line  16  is compressed by the fire-protection element  26 , thereby completely sealing off the passage  14 . 
         [0040]    As can be seen in  FIG. 5 , the intumescent material causes the anchoring element  34  to be bent on the radial outside  36  radially inwards into the passage  14 , so that the anchoring element  34  projects radially inwards from the inner wall of the housing  18  after the fire-protection element  26  has swelled up. 
         [0041]    In this position, the fire-protection element  26  is securely held by the anchoring element  34  and cannot be moved out of the holding space  25  of the line conduit  10  or out of the passage  14 . As a result, the line conduit  10  or the fire-protection element  26  can reliably seal off the passage  14 , even under strong forces, for instance, due to the impact of a jet of water. 
         [0042]    The prior-art fire-protection elements  26  were only able to withstand such forces if the intumescent compound of the fire-protection element  26  was dimensioned so as to be correspondingly larger. Thanks to the line conduit  10  according to the invention, the fire-protection element  26  can be configured so as to be considerably smaller and more compact since the anchoring element  34  accounts for a much better fixation of the fire-protection element  26  in the passage  14 . 
         [0043]    In order to attain better heat conduction into the fire-protection element  26  and thus a faster activation of the fire-protection element  26 , the holding section  24  is preferably made of a metal having high thermal conductivity. The rest of the housing  18  as well as the anchoring element  34  can be partially made of metal or plastic. 
         [0044]    The anchoring element  34  preferably has interruptions in the circumferential direction so that it can be easily bent radially inwards. It is also conceivable to provide several anchoring elements  34  that are distributed in the circumferential direction. They do not have to extend in the lengthwise direction L into the fire-protection element  26 . All that has to be ensured is that the anchoring elements  34  remain inside the fire-protection element  26  after the latter has swelled up so as to ensure that the fire-protection element  26  is held in the passage  14 . 
         [0045]    The fire-protection element  26  likewise does not have to project outwards in the radial direction beyond the first or second section  20 ,  22 . Therefore, the inner wall of the housing  18  can also have a constant diameter throughout, so that during assembly, a line  16  cannot get caught on a protruding fire-protection element  26 . 
         [0046]    The sections  20 ,  22  can also be configured differently, whereby the position of the fire-protection element  26  can be varied by means of the length of the sections  20 ,  22 . 
         [0047]    In particular, it is also conceivable to have a configuration with only one section  20 ,  22 . 
         [0048]    A section  20  on which there is no anchoring element  34  can also be configured in such a way that it can be removed after the structural element  12  has been made. 
         [0049]    The holding space  25  can also be closed off vis-à-vis the mold  30  by means of a second closure element that can be provided on the first section  20 .