Abstract:
A system and method for passing conduit through a wall so as to maintain a firebreak for the wall wherein a coupling having relatively low thermal conductivity properties and relatively high fire resistance properties is mounted in an opening in the wall and secured therein by thermal barrier sealing material and one end of a first conduit is inserted into a first side of the coupling and one end of a second conduit is inserted into a second side of the coupling and wherein the first and second conduits have relatively high thermal conductivity properties and wherein the one ends of the first and second conduits are located and maintained a distance from each other so as to provide a thermal barrier therebetween.

Description:
FIELD OF THE INVENTION 
     This invention relates generally to the use of firebreaks to prevent the spreading of fires particularly in buildings and more specifically to a system for providing a firebreak for conduits so as to prevent the spreading of a fire from one floor to another floor or one room to another room. 
     BACKGROUND OF THE INVENTION 
     The building codes in many localities require the use of firebreaks in the construction of buildings so as to prevent or hinder the spreading of fire from one floor to another floor or one room on a level to another room on the same level. In present practice, when a conduit, such as one used for carrying electric cable, passes from one floor to another floor through a ceiling, the area surrounding the opening through which the conduit passes is filled with a thermal barrier material to function as a firebreak. However, the conduit itself is usually formed from metal and has a relatively high thermal conductivity. Therefore, if a fire breaks out on one floor, the conduit on that floor heats up to a high temperature and conducts a high percentage of that heat to the next adjacent portion of the conduit in the next adjacent floor. If there are flammable materials close to the portion of the conduit to which the heat has been conducted, then there is a good possibility that the flammable material would be ignited and propagage the fire. 
     BRIEF SUMMARY OF THE INVENTION 
     This invention provides a firebreak for conduits wherein a thermal barrier is provided between a conduit in one floor and a conduit in another floor so that if a fire starts on the one floor and heats the conduit to a high temperature, only an extremely small percentage of that heat is transferred to the conduit in the another floor so as to eliminate the danger of igniting flammable material in the another floor. 
     In the preferred embodiment of the invention, the firebreak includes opening means defining an opening extending through a wall between one floor and another floor. A coupling means is mounted in the opening and secured therein by a thermal barrier sealing material forming a seal between the coupling means and the opening means. The coupling means is formed from a material having relatively low thermal conductivity properties and relatively high fire resistance properties. One end of a first conduit means is inserted into a first side of the coupling means and one end of a second conduit means is inserted into the second side of the coupling means. The first and second conduit means are usually formed from metal and have relatively high thermal conductivity properties. Separation means are provided in the coupling means to provide a positive space between the one ends of the first and second conduit means in the coupling means. Retaining means are provided for exerting a retaining force on the one e nds of the first and second conduit means after they have been inserted into the coupling means. Therefore, if a fire breaks out on the one floor in which the first conduit means is located, the first conduit means will be retained in the coupling means so that the fire can not be transmitted through the coupling means. The separation between the one ends of the first and second conduit means and the relatively low thermal conductivity properties of the coupling means provide structures that permit only an extremely small percentage of any heat generated in the first conduit means as a result of a fire to be conducted to the second conduit means. Electrical conducting means are provided in the coupling means and provide a continuous electric circuit between the one ends of the first and second conduit means in the coupling means for purposes such as grounding means. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     An illustrative and presently preferred embodiment of the invention is shown in the accompanying drawings in which: 
     FIG. 1 is a cross-sectional view illustrating the invention; 
     FIG. 2 is a cross-sectional view taken on the line 2--2 of FIG. 1; 
     FIG. 3 is a cross-sectional view of the coupling means; 
     FIG. 4 is a front elevational view of the retaining means; 
     FIG. 5 is a cross-sectional view taken on the line 5--5 of FIG. 4; 
     FIG. 6 is a partial cross-sectional view of a portion of another embodiment of the invention; 
     FIG. 7 is a cross-sectional view of a preferred embodiment of the electrical conducting means; and 
     FIG. 8 is a cross-sectional view of a portion of another embodiment of the electrical conducting means. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The preferred embodiment of the invention is illustrated in FIG. 1 wherein a wall means 2 is provided to separate one floor 4 from another floor 6. An opening 8 is formed by the side wall opening means 10 and extends through the wall means 2. A coupling means 12 is positioned in the opening and secured therein using a thermal barrier sealing material 14 to fo rm a thermal seal between the coupling means 12 and the side wall opening means 10. A first conduit means 16 is inserted into a first side of the coupling means 12 and a second conduit means 18 is inserted into a second side of the coupling means 12. The first and second conduit means 16 and 18 are formed from metal and have a thermal conductivity greater than 22 B.t.u. per hr-ft-deg F. 
     The coupling means 12 is specifically illustrated in FIG. 3 and comprises an elongated hollow member 20 having generally cylindrical outer 22 and inner 24 surfaces and opposite end portions 26 and 28. Two spaced apart, annular, radially outwardly extending grooves 30 and 32 are formed in the generally cylindrical inner surface 24. Separation means 34 comprises an annular radially inwardly extending projection means 36 having a generally cylindrical inner surface 38 which has a diameter substantially less than the diameter of the generally cylindrical inner surface 34. A central longitudinal axis extends through the elongated hollow member 20 between the opposite end portions 26 and 28. The coupling means 12 is formed from a material having a thermal conductivity of less than 4.0 B.t.u. hr-ft-deg F. and a fire resistance rating in accordance with ASTM-Test E 814 of at least 3 hours. 
     The retaining means 40, illustrated in FIGS. 4 and 5, comprises a split locking ring 42 having a space 44 between the ends 46 and 48 thereof. Two axially extending gripping members 50 and 52 are provided next to each of the ends 46 and 48. Each gripping member 50 and 52 has a radial extent substantially less than the radial extent of the split locking ring 42 so as to allow the split locking ring 42 to be positioned in one of the grooves 30 or 32. The split locking ring 42 is formed from a resilient material, such as carbon steel spring, so that the gripping members 50 and 52 may be squeezed toward each other to reduce the outer diameter of the split locking ring 42 which is then inserted into the elongated hollow member 20, positioned radially opposite one of the grooves 30 and 32 and then the gripping members 50 and 52 are released so that the split locking ring expands and is seated in one of the grooves 30 or 32. A plurality of radially inwardly extending, spaced apart fingers 54 are integral with the split locking ring 42. After the split locking ring 42 has been inserted into the groove 30 or 32 and a conduit is inserted into the elongated hollow body 20, the fingers 54 will flex in an axially inward direction to allow for passageway of the conduit through the split locking ring 42. However, if an attempt is made to move the conduit out of the elongated hollow body 20, the fingers 54 will exert a force on the outer surface of the conduit to restrain its withdrawal. 
     In FIG. 6, there is illustrated another embodiment of the invention. Protection means 60 are provided for protecting the coupling means 12 from any hard blows or falls or shear forces. This is desirable since the coupling means 12 in the preferred embodiment of the invention is formed from a ceramic material. The protection means 60 comprises an elongated cover 62 having generally cylindrical outer 64 and inner 66 surfaces and opposite end portions 68 and 70. The elongated cover 62 is formed from a relatively rigid material such as steel. The end portions 68 and 70 have an inner diameter greater than the diameter of the cylindrical inner surface 24 so as to be spaced a distance from each of the first and second conduit means 16 and 18. Also, additional thermal barrier sealing material 14 has been applied to encase the outer exposed portions of the protection means 60 and fill the space between the end portions 68 and 70 and the first and second conduit means 16 and 18. 
     Electrical conducting means 80 are provided for the coupling means 12 and in FIG. 7 comprises an axially extending groove 82 formed in the cylindrical inner surface 24 so that it extends radially outwardly therefrom. A strip 84 of an electrical conducting material is secured in the groove 82 and has exposed end portions 86 and 88 in the groove 30 and 32. When the split locking rings 42 have been inserted into the grooves 30 and 32 and the first and second conduit means 16 and 18 have been inserted into the coupling means 12, there exists a continuous electrical conducting circuit between the first and second conduit means 16 and 18, the split locking rings 42 and the strip 84 to provide an electrical grounding circuit. 
     The electrical conducting means 80 in FIG. 8 comprises an electrical conducting wire 90 embedded in the elongated hollow member 20 and having exposed end portions 92 and 94 in the grooves 30 and 32 so as to cooperate with the split locking rings 42 and the first and second conduit means 16 and 18 so as to provide the continuous electrical grounding circuit as described above. 
     In operation, a split locking ring 42 is positioned in each of the grooves 30 and 32 and the coupling means 12 is mounted in the opening 8 using the thermal barrier sealing material 14. One end 96 of the first conduit means 16 is inserted into a first side of the coupling means 12 and deflects the fingers 54 of the split locking ring 42 axially inwardly. The movement of the first conduit means 16 is continued until it contacts the separation means 34. One end 98 of the second conduit means 18 is inserted into a second side of the coupling means 12 and deflects the fingers 54 of the split locking ring 42 axially inwardly. The movement of the second conduit means 18 is continued until it contacts the separation means 34. As illustrated in FIG. 1, there exists a space between theone end 96 and the one end 98. Therefore, since the coupling means 12 is formed from a material having relatively low thermal conductivity properties, such as a ceramic material, only a relatively small percentage, less than 30 per cent of heat, can be transferred from the first conduit means 16 to the second conduit means 18 if the first conduit means is exposed to a fire. The amount of heat that can possibly be transferred through the coupling means 12 significantly reduces the possibility of igniting any flammable material in the another floor 6. 
     The coupling means 12 is dimensioned to cooperate with the size of the conduit means. In one embodiment of the invention, the conduit means has an outer diameter of about 1.315 inches, the elongated hollow member 20 has a length of about 3.0 inches, an outer diameter of about 2.5 inches, and an inner diameter of about 1.5 inches. Each groove 30 and 32 has a depth of about 0.15 inches. The separation means 34 has an inner diameter of about 1.05 inches and an axial extent of about 0.5 inches. The split locking ring has a normal diameter of about 1.3 inches. 
     The coupling means 12 is formed from a ceramic material having a thermal conductivity of about 0.4 B.t.u. per hr-ft-deg F and a fire resistance rating in accordance with ASTM-Test E 814 of at least 3 hours. Other materials, such as plastic composite, may be used to form the coupling means 12 provided they have the thermal conductivity and fire resistance rating as described above. 
     While an illustrative and presently preferred embodiment of the invention has been described in detail herein, it is to be understood that the inventive concepts may be otherwise variously embodied and employed and that the appended claims are intended to be construed to include such variations except insofar as limited by the prior art.