Abstract:
An intumescent structure provides a hermetic-type barrier within a fiber duct through which communications cabling is extended. The structure is formed of a fire-resistant body possessing a plurality of pre-perforated forms that extend through the body. Each of the pre-perforated forms may be sized to have cross-sectional dimensions and geometries that generally correspond to the cross-sectional configurations of communications cabling that are typically placed in a fiber duct to interconnect electronic equipment. Selective removal of the pre-perforated forms establish associated passageways through the body for receiving the appropriately sized cabling therethrough. This facilitates the maintenance of a barrier to gasses and other substances escaping through the duct, while still allowing cabling to freely pass through the duct.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not applicable. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     BACKGROUND OF THE INVENTION 
     Buildings that house electronic telecommunications equipment may be segmented into a number of rooms. In the case of mobile switching centers (MSCs), or similar facilities, one or more rooms may house various servers, routers, switches, and other telecommunications equipment, and another set of rooms may house computers that control operation of such equipment. Many advantages are provided by maintaining certain electronic equipment in separate rooms, including configuration of the indoor environment (e.g., temperature and humidity) for reliable operation of specific types of equipment, efficiency of operation and ease of interconnectivity of related equipment in close proximity. 
     Electronic equipment spread across various rooms of an MSC may be interconnected through communications cabling, or fiber, that extends through fiber ducts formed in the walls separating the rooms. These fiber ducts present problems when planning a fire suppression scheme for a multi-room facility. A given facility will typically have a fire suppression system specifically designed to put out the types of fires that are commonly encountered, such as electrical fires. Traditional fire suppression systems utilized where electronic equipment is present accomplish their intended function by either (a) absorbing a large amount of heat energy present in a room to reduce the surface temperature of burning material below it&#39;s ignition point, or (b) reducing the oxygen level in a room to a level that is too low for combustion to occur. For instance, fire suppression systems that work on the principle of heat energy absorption may employ various gasses and aerosols, such as potassium compounds suspended in carrier gasses, that are discharged into a particular room when a fire is detected. A similar principal may be applied in systems that reduce room oxygen levels, such as by the discharge of gasses containing a high concentration of carbon dioxide. In either case, the effectiveness of the fire suppression system depends on the ability to maintain the discharged gasses within a room of a given volume until the fire has been eliminated. Unfortunately, fiber ducting provides a path by which the discharged gasses can leave a room, reducing the effectiveness of fire suppression. This is because the cabling does not completely fill the space at the entrance and exit regions of the duct. The fiber ducting may also provide a direct path by which a fire may travel between rooms. 
     Efforts to fill in the open space around cabling within a duct have led to the use a fire barrier “pillows” or “blocks”. These blocks are formed of materials that have a high ignition temperature to resist being consumed by a fire, as well as with intumescent properties so that the blocks expand to fill an open space when exposed to the extreme heat of a fire. Once cabling is extended through a duct, the blocks are placed in the opening of the duct around the cabling. 
     Fire barrier blocks are effective in blocking the escape of fire suppression system gasses to some degree, but an airtight seal remains difficult within a duct due to imprecision of fitting one or more blocks around cabling and cable trays or within cable-carrying conduits of varying geometries. It is also labor intensive for an installer to cut the blocks on site in order to achieve an improved geometry within the duct for a tighter fit around the cabling. 
     BRIEF SUMMARY OF THE INVENTION 
     An intumescent structure provides for increased efficiencies in the creation of a hermetic-type barrier within a fiber duct through which communications cabling is extended. The intumescent structure may have a perimeter geometry specifically selected for an optimal fit within a duct spanning through a wall to connect adjacent rooms or within a cable-carrying conduit. Additionally, intumescent structure installation, in one configuration, may be made before or after cabling has been extended through the duct. These properties of the intumescent structure improve the ability of fire suppression systems to quickly and effectively impede the spread of a fire. 
     In one aspect, the intumescent structure is formed of a fire-resistant body possessing a plurality of pre-perforated forms that extend through the body. Each of the pre-perforated forms are spaced from one another and may be sized to have cross-sectional dimensions and geometries that generally correspond to the cross-sectional configurations of communications cabling that are typically placed in a fiber duct in connecting electronic equipment. Either before or after the intumescent structure is placed directly in a fiber duct or within a fiber-carrying conduit designed for placement within the duct, the pre-perforated forms may be selectively removed to establish one or more passageways through the body for receiving the appropriately sized cabling therethrough. This facilitates the maintenance of a barrier within the duct that approaches being a complete block to the passage of gasses and other substances, while still allowing cabling to freely pass through the duct. 
     In another aspect, the pre-perforated forms in the body of the intumescent structure may be aligned with one another in various rows. To provide for installation of the intumescent structure with existing cabling within the duct, pre-perforated divider lines may be formed in the body and arranged to bifurcate the rows of pre-perforated forms and facilitate disassembly of the body into discreet layers. This allows the layers of the intumescent structure to be installed around the cabling without having to remove the cabling from the end connections with electronic equipment. 
     The apparatus of yet another aspect provides a way for guiding communications cabling through a fiber duct while maintaining a hermetic-type barrier in the duct. Included in the apparatus are a conduit sized to fit within the fiber duct and one or more intumescent fire-resistant blocks disposed generally near one of the opposing opening ends of the conduit. Each intumescent fire-resistant block has a cross-sectional geometry that is generally congruent with the cross-sectional geometry of the opening defined by the respective opening ends of the conduit. Furthermore, a plurality of pre-perforated forms extend through each intumescent fire-resistant block in the longitudinal direction of the conduit, such that selected removal of the forms creates passageways that allow communications cabling to extend through each block and through the fiber duct. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
       In the accompanying drawings which form a part of the specification and are to be read in conjunction therewith and in which like reference numerals are used to indicate like elements in the various views: 
         FIG. 1  is a perspective view of the intumescent structure positioned within a cable carrying conduit in accordance with one embodiment of the present invention; 
         FIG. 2  is a sectional view of a wall having a fiber duct extending therethrough with the cable carrying conduit and intumescent structures located in the fiber duct and supporting cabling; 
         FIG. 3  is an exploded perspective view depicting the removal of the lid of the cable carrying conduit to show the cabling installed through the intumescent structures; 
         FIG. 4  is a perspective view with the lid of the cable carrying conduit removed to show the discreet layers of the intumescent structure; and 
         FIG. 5  is a perspective view of the intumescent structure depicting the separation of a discreet layer along one pre-perforated divider line. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now in more detail to the drawings, and initially to  FIG. 1 , there is illustrated an embodiment of a communications cabling guiding apparatus of the present invention designated by the reference numeral  10 . The apparatus  10  includes a conduit  12  and one or more intumescent fire-resistant structures  14  configured for positioning within the conduit  12 . As can be seen with additional reference to  FIGS. 2 and 3 , the conduit  12  may be sized to fit within a fiber duct  100  extending through a fire-rated or non-fire rated wall  102  dividing adjacent rooms. More specifically, opposed end portions  16  of the conduit  12  may have a perimeter geometry that is the same as the inside surface of the walls of the duct  100 , so that the end portions  16  fit tightly within openings  104  of the duct  100 . This inhibits the passage of air through the duct  100  around the outside of the conduit  12 . Alternatively, various fire-resistant materials, such as those made of the same material as the intumescent structure  14 , as will be more fully explained below, may be positioned around the outside of the conduit  12  and within the duct  100  to provide a substantially air tight fit around the conduit  12 . Conduit  12  may be formed by a trough  18 , and optionally with a coupler  20  attached to one or both opposed ends  22  of the trough  18 , as well as a lid  24 . Depending on the thickness of the wall  102 , multiple troughs  18  and couplers  20  may be connected end-on-end to form the conduit  12 , with each trough  18  and pair of couplers  20  having one lid  24 . Exemplary conduit  12  structures may include those offered by Telect, Inc. of Liberty Lake, Wash. 
     Each intumescent structure  14  has a body with a cross-sectional geometry designed to generally mimic the cross-sectional geometry of the portion of the conduit  12  in which the structure  14  is to be located. For instance, a pair of intumescent structures  14  located within openings  26  in the opposed end portions  16  of the conduit  12  (i.e., the space bounded by each coupler  20  and the lid  24 ) have geometries that generally fill the space of the openings  26 , as best seen in  FIG. 3 . More details about the configuration and usage of the intumescent structure  14  can be understood with additional reference to  FIGS. 3-5 . 
     One suitable embodiment provides the intumescent structure  14  as flexible, fire and smoke resistant urethane foam members. This type of material allows for deformation of the structure  14  to fully adapt to the shape of the conduit openings  26 , thereby ensuring a fairly tight fit within the conduit  12 . Upon receiving heat energy from a fire, the intumescent structure  14  expands within the conduit openings  26  to create a substantially full hermetic barrier to prevent gasses from fire suppression systems from escaping a room through the fiber duct  100  as well as inhibiting the spread of a fire through the duct  100 . Examples of products that provide the type of material well suited for forming the intumescent structure  14  include those offered under the name “FS 657 Fire Block” by Hilti Corp. of Tulsa, Okla., and “Fire Barrier Pillow” by 3M Company of St. Paul, Minn. 
     The intumescent structure  14  can be seen in detail in  FIG. 5 , and is provided with a plurality of spaced apart pre-perforated forms  28 . The selected removal of specific forms  28  allows for cabling  200  of varying cross-sectional dimensions (e.g., communications or power cables) to be extended through the intumescent structure  14  and the conduit  12  while minimizing any air passageways through the fiber duct  100 , as is depicted in  FIGS. 2-4 . The cross-section of the forms  28  is preferably selected to closely mimic the cross-section of typical communications cabling  200  so that passageways  30  created by removal of the forms  28  are generally the same size as the cabling  200 . For instance, the forms  28  may be right circular cylinders or any other profile that cabling  200  may take. Preferably, the forms  28  are arranged in rows  32  and extend through the intumescent structure  14  in parallel fashion from a first side  34  to an opposed second side  36 . This alignment positions the forms  28 , and therefore the passageways  30 , in axial alignment with the longitudinal direction of the conduit  12  through which the cabling  200  extends. Each row  32  may have forms  28  all of the same cross-sectional shape and dimensions, or may have forms  28  of multiple sizes. 
     One method of creating the forms  28  involves puncturing the intumescent structure  14  completely through from the first side  34  to the second side  36  to create a hole that is fairly narrow in cross-section. Then, in view of the desired geometry of the passageway  30  created by removal of the form  28 , the point of puncture is moved a small amount to an adjacent location. If a cylindrical passageway  30  is desired, the puncture point is moved a few degrees around the circumference of the circle outline at the first side  34 , and the process is repeated until the given form  28  is fully generated. Enough punctures should be created for a given form  28  so that a reasonable amount of pushing force applied to the form  28  on one of the first side  34  or second side  36  in the axial direction will cause the form  28  to tear away from the body of the structure  14  and leave behind the passageway  30 . The cabling  200  corresponding to the particular size of the form  28  removed from each structure  14  may then be slid through the passageways  30  of each structure  14  and through the conduit  12  to reach adjacent rooms, as depicted in  FIGS. 2-4 . Depending on the access to the fiber duct  10  and within the conduit  12 , the cabling  200  may be extended through the passageways  30  before or after the structures  14  are fully installed in the conduit  12 . It should also be observed that because of the intumescent nature of the structure  14 , the perforation punctures, as well as any small gaps between cabling  200  and the inside walls of the passageways  30  in use, do not provide weak points in the hermetic barrier provided by the structure  14 . More specifically, the heat of a fire in a room serviced by the fiber duct  100  causes material expansion of the structures  14 , which will substantially closes the punctures and any air gaps. 
     The arrangement of the rows  32  of forms  28  is also beneficial to the installation of intumescent structures  14  within a conduit  12  where cabling  200  has already been extended through a fiber duct  100  and disconnecting the ends of the cabling  200  for connections with electronic equipment would be laborious or otherwise undesirable. For instance, the cabling  200  may already connect various computers in different rooms such that disconnecting a cable end for extending through one of the passageways  30  of the intumescent structure  14  would result in an interruption of service. Therefore, the rows  32  may each be bifurcated by pre-perforated divider lines  38  so that discreet layers  40  are created when the intumescent structure  14  is pulled apart along the lines  38 . Preferably, the rows  32  are horizontally-aligned so that the divider lines  38  form the layers  40  as stacked one above the other, and separation along the divider lines  38  creates vertically-adjacent layers  40  each having a portion of a given form  28 , as best seen in  FIGS. 4 and 5 . Upon selected removal of forms  28 , and at least partial division of the structure  14  along respective divider lines  38 , cabling  200  can be positioned in a lower portion  42  of a resulting passageway  30  in one layer  40  and an overlying layer  40  aligned with and placed on top of the underlying layer  40 . Preferably, the installation process starts with a lowermost layer  44  and continues until the full stack of layers  40  is in place. The weight of overlying layers  40  and supported cabling  200 , as well as any compression force provided by lid  24 , aid in keeping the divided layers  40  together to minimize air gaps through the structure  14 . It should be understood that selected forms  28  may be removed to expose passageways  30  before or after separation of the structure  14  along one or more of the divider lines  38 . 
     One advantage of having each rows  32  of forms  28  with a limited number of sizes is that installation of the intumescent structure  14  can be expedited. An installer can organize the number of cables  200  of a given size together that extend through a given fiber duct  100 , and then remove the proper number of forms  28 . Thus, a lowermost layer  44  can be put in place within the conduit  12  and the appropriately sized cables  200  (e.g., small diameter cables) positioned in the lower portion  42  of the passageway  30 . The next layer  40  is then positioned directly on top of the lowermost layer  44 , and the next size of cables  200  are positioned thereon. This process continues until the layers  40  are all stacked together as the complete intumescent structure  14 . 
     Although the apparatus  10  is depicted in the figures as having a pair of intumescent structures  14  disposed at opposed ends  16  of the conduit  12 , one or any number of such structures  14  may be utilized in the present invention, and may be positioned at any desired longitudinal point along the conduit  12 . It should be also understood that one or more intumescent structures  14  may be utilized within a fiber duct  100  without a conduit  12  that carries cabling  200 . In such an arrangement, the intumescent structure  14  should be sized and configured to fit fairly tightly within the fiber duct  100  so that a small amount of dimensional expansion that takes place when the structure  14  receives heat energy creates the desired hermetic barrier within the duct  100 . 
     Therefore, it can be seen that the intumescent structure  14  and apparatus  10  of the present invention provides an effective hermetic barrier within a fiber duct to aid in fire suppression efforts in various types of facilities. Various embodiments of the intumescent structure  14  allow for efficient installation of the hermetic barrier at the time of initial cable installation or when existing cabling is already in place and in use at a facility. Furthermore, it should be understood that various modifications may be made to the embodiments of the present invention described herein without departing from its scope, and that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the present invention. It is also to be understood that all matter herein set forth or shown in the accompanying drawings is to be illustrative of applications of the principles of the invention, and not in a limiting sense.