Abstract:
A cast-in-place coupling ( 6 ) is positioned on concrete forms ( 2 ) by detachable attachment means ( 7, 10 ). The coupling ( 6 ) may have breakaway tabs ( 7 ) or may be frictionally engaged to a fitting ( 10 ) fastened to a form ( 2 ). After concrete is poured the attachment means ( 7, 10 ) is separated from the coupling ( 6 ) with minimum effort and inconvenience. The coupling ( 6 ) itself contains an intumescent which causes the coupling ( 6 ) to convert to a firestop under file conditions.

Description:
FIELD OF THE INVENTION  
         [0001]    This invention relates to structures in which a separation in a building, e.g. a floor or wall, is penetrated by “penetrations”, e.g. pipes, electrical conduit, mechanical ventilation or communication wiring within the building. In particular, it relates to a coupling which is installed in place within separations when the structure is being created to allow plastic piping and/or conduit systems to pierce or penetrate fire separations in buildings. More particularly, it relates to cast-in-place couplings that serve as fire stops.  
         BACKGROUND TO THE INVENTION  
         [0002]    It is well known to provide fire stops for non-metallic pipes and electrical non-metallic conduit that pass through building separations. This is generally achieved through use of fire-activated collars and wraps.  
           [0003]    Both plastic piping and the fire separations travel in both horizontal and vertical directions. Most horizontal floors separations&#39; are constructed with reinforced concrete cast using reusable forms or cast onto metal decks with a steel frame. The vast majority of vertical fire walls are made of concrete block, gypsum wall board with metal or wood framing. This invention relates to providing a plastic fire stop coupling suitable for use with each of such types of penetration locations.  
           [0004]    Firestops act on the basis of the expansion of intumescent materials. When activated the intumescent swells filling the voids in the separation, particularly openings in plastic pipes, by filling or diminishing the diameter of the plastic pipe. The object is to limit the spread of fire to a hourly rating equal to the grade of the surrounding separation.  
           [0005]    In typical cases no allowance is made for movement or lateral shear caused by movement due to floor loading, building creep, seismic activities, and mechanical vibration.  
           [0006]    In some cases firestop devices direct the expanding intumescent inwards using steel housings. These housings are mechanically attached to the fire separation surrounding the pipe. Fire resistant mineral wool and sealant are also used to bring the fire rating of the penetration up to the grade of the separation.  
           [0007]    Another less commonly used device allows an intumescent wrap to be bonded to the exterior of a coupling, installing the coupling at the location where the penetration pierces the separation. Such a system is shown in U.S. Pat. No. 5,634,304. Other patents have issued disclosing the use of intumescents within plastics compositions intended for production of injection molded shapes. Examples are referenced in U.S. Pat. No. 5,934,333 and European applications EP 0 302 987 and EP 0 745 751. What these patents do not disclose is the expansion factor of the intumescent additive. The expansion factor of the intumescent will affect the percent of intumescent needed in the coupling composition in order to close the pipe opening during a fire.  
           [0008]    Non-metallic pipe coupling designs through-out the world bear many similarities. The sockets or receiving portions of the couplings are tapered to allow for snug fits with pipe ends using solvent welding solutions to bond piping effectivity. The solvent weld solution also lubricates the joint to ensure the penetrating pipe end slides into the receiving socket by an appropriate distance.  
           [0009]    Existing couplings are provided with inner end stops to ensure that the pipe does not advance too deeply into the coupling and occupy space designated for the adjoining pipe. Such inner end stops protrude inwardly with an interior dimension no more than the wall thickness of the corresponding pipe. This ensures that the flow of materials within the pipe is not restricted. This end-stop height is normally no more than  6 mm in height. This is usually the bare minimum height required to stop the advancement of the pipe into the coupling.  
           [0010]    Accordingly, one object of this invention is to both provide an end stop within a molded pipe coupling while also providing for an increased thickness of potentially expanding composition to fill the void across the pipe under fire conditions.  
           [0011]    Additionally another object of this invention is to place the greatest volume of intumescent at the underside location of floor applications so that a fire activates the intumescent/composition matrix more promptly.  
           [0012]    In this aspect of the invention, suited for the use and subsequent removal of a forming ring during concrete pouring, an enhanced volume of the coupling material is positioned to be exposed to fire so intumescent materials are activated more efficiently.  
           [0013]    Another object of the invention is to provide a convenient means for positioning cast-in-place couplings within cast building separations.  
           [0014]    In contemporary building techniques based on poured concrete structures, couplings for penetrations are fastened in-place to forms used to cast concrete separations at their destined locations before the concrete is poured. “Coupling” herein includes both actual couplings which are part of conduits and the like, as well as sleeves which provide openings or penetrations through concrete separations through which conduit and the like may pass.  
           [0015]    Mechanical straps and the like have been used to position couplings at their locations before the concrete is poured. In particular, existing systems rely on the use of nails driven into wooden forms to attach couplings to such forms. This creates difficulties after the concrete has set and the forms are to be removed. Often nails are left protruding from the poured concrete with their pointed ends exposed and their head ends deeply embedded. This is not only dangerous but requires considerable labour to remove such nails in a safe manner without damaging the couplings.  
           [0016]    An improved method for fastening couplings in place on concrete forms is required. A further requirement is to provide an efficient manner of sealing the top of the coupling or sleeve from concrete contamination during the concrete pouring process to allow for easy access after the concrete is cured in order to insert the pipe into the coupling or sleeve. This invention addresses these needs.  
           [0017]    The invention in its general form will first be described, and then its implementation in terms of specific embodiments will be detailed with reference to the drawings following hereafter. These embodiments are intended to demonstrate the principle of the invention, and the manner of its implementation. The invention in its broadest and more specific forms will then be further described, and defined, in each of the individual claims which conclude this Specification.  
         SUMMARY OF THE INVENTION  
         [0018]    According to the invention in one aspect, a molded or cast non-metallic coupling of polymeric material is formulated using intumescent additives within the forming material itself. Further, the wall thickness of the coupling in its central portion, between sockets to receive pipe ends, is enhanced over the wall thickness in the socket portions of the coupling. This increased thickness is intended to provide for the presence of sufficient intumescent material to ensure the collapse and sealing of the coupling under fire conditions. The wall thickness of the coupling could be increased over the entire length of the coupling to achieve this fire stopping result. However, it is sufficient to provide only such increased thickness in the central portion of the coupling, between the end stops that are provided to locate the pipe ends, as is required to seal-off the coupling.  
           [0019]    Firestop couplings according to this aspect of the invention incorporate an intumescent additive that forms an integral part of the material of the coupling. Preferably the coupling is made of a material that is compatible with being structurally joined, as by solvent binding or other equivalent, to the piping or conduit system. The coupling may receive its shape by being injected molded, extruded or machined. It may thereby be provided with a central portion wall thickness that is greater than wall thickness of the piping or conduit to which it is coupled. This thickened central wall portion of the coupling may also serve to provide the end stop for the sockets in the coupling.  
           [0020]    The coupling may be fabricated of any suitable material. Preferred materials include injection molded or extruded polyvinylchloride or chlorinated polyvinylchloride. Also suitable are plastics such as ABS, polypropylene, polyethylene and polybutles. These plastics are available in both rigid and flexible forms. Accordingly, a coupling may be made of a composition that will both intumesce on exposure to fire and which exhibits flexibility to reduce stress on the joint between pipe and coupling.  
           [0021]    Preferably the composition of the coupling contains an intumescent additive wherein the intumescent additive is between 5 and 30% by weight of the composition, more preferably between 15 and 25% by weight of the composition, still more preferably between 15 and 20% by weight of the composition. This intumescing additive should preferably provide a volume expansion that is greater than 3 times, more preferably within the range of at least 4 to 6 times. It may also contain a heat activated expanding agent such as fluid or gas containing expanding beads or gas generants wherein the heat activated expanding agent is between 0.5 and 3% by weight of the composition.  
           [0022]    The invention also provides a firestop coupling molded from a flexible matrix to accommodate pipe displacement with respect to the penetration. Further, addition coupling wall thickness containing intumescent material may be provided, sufficient to close a perimeter gap around the outer circumference of the coupling, crushing any loose packing present therein.  
           [0023]    The fire stop coupling of the invention may be provide with at least one tapered receiving end to accommodate solvent welding.  
           [0024]    According to the invention in another aspect, a coupling is provided with a detachable attachment means that is formed integrally with the coupling. Preferably this is in the form of a footing or tab with a hole formed therein that extends laterally from one end of a coupling. Nails, screws or other fastening means pass through the hole to fix the coupling to a form before concrete is cast.  
           [0025]    This tab is joined to the coupling by a break-away connection. Once cast in place, the tab will separate from the coupling under moderate force, allowing nails to be readily removed from the cast structure.  
           [0026]    As an alternate arrangement, the coupling is shaped to receive a fitting that detachably engages with one end of the coupling. A frictional fit is sufficient for these purposes. For this purpose, a generally cylindrical coupling may be provided at one end with an outer surface that is formed, as by inclined e.g. flats or a conical taper, to engage with complementary surfaces on a form-mounted fitting that serves as a detachable attachment means. The fitting is provided with a hole through which a fastener, e.g. a nail or screw, may be placed to attach it to a form. In this case, the fitting will stay with the form when the form is removed from the cast structure. Advantageously, the form may be re-used with the fitting fixed in the same place.  
           [0027]    In either case, any fastener placed through the hole provided on the detachable attachment means will, after the concrete is poured, be barely embedded within the cast concrete. Accordingly, the attachment means can be separated from the coupling and be readily removed from the concrete. Particularly, nails will separate automatically from the concrete when the forms are removed. Thereafter, such nails may readily be removed from the forms by pulling upon their head ends.  
           [0028]    The foregoing summarizes the principal features of the invention and some of its optional aspects. The invention may be further understood by the description of the preferred embodiments, in conjunction with the drawings, which now follow. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0029]    [0029]FIG. 1 is a schematic side view of a prior art system by which a coupling is fastened to a wooden form panel before the pouring of concrete occurs.  
         [0030]    [0030]FIG. 2 is a schematic side view of a coupling according to the invention provided with an integrally attached, detachable coupling means which is attached to a wooden form panel before the pouring of concrete.  
         [0031]    [0031]FIG. 3 is a schematic side view of a coupling according to the invention provided with a frictionally detachable coupling means, in position, attached to a wooden form panel before the pouring of concrete.  
         [0032]    [0032]FIG. 4 is a perspective view of a coupling with two break-away flanges as in FIG. 2.  
         [0033]    [0033]FIG. 5 is a cross-sectional side view of the coupling of FIG. 4 also showing the internal profile wherein the central wall portion is of greater thickness than the socket walls.  
         [0034]    [0034]FIG. 6 is a cross-sectional side view of the conduit and fitting of FIG. 3 also showing an internal profile as in FIG. 5.  
         [0035]    [0035]FIG. 7 is a cross-section of a prior art pipe coupling.  
         [0036]    [0036]FIG. 8 is a cross-section of a pipe coupling according to the invention.  
         [0037]    [0037]FIG. 9 is a cross-section of a pipe coupling with a frangible diaphragm cast into a concrete wall.  
         [0038]    [0038]FIG. 10 is a cross-section of the coupling of FIG. 9 with the diaphragm and adjacent concrete ruptured to allow entry of a pipe end.  
         [0039]    [0039]FIG. 11 is a cross-section of the coupling of FIG. 8 installed in a penetration with glass fibre packing and a silicone layer end seal. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0040]    A coupling according to one aspect of the invention is depicted in FIGS. 5, 6,  8 - 11 . A cylindrical sleeve  6  has a plain exterior in the shape of a circular cylinder. Internally, sockets  20  have walls of a given thickness. The center portion  21  between the sockets  20  has an increased wall thickness. The thickness of the wall in the center portion  21 , combined with the amount of intumescent material present, and the nature of the composition of the conduit itself, combine to ensure that a sealing collapse will occur under fire conditions. The central portion  21  serves as a stop to limit excessive penetration of pipe ends into the coupling. The sockets  20  are preferable tapered in the known manner to facilitate reception of the pipe ends.  
         [0041]    In FIG. 1 a prior art panel  2  on a form or mold for casting a floor has a coupling  1  mounted thereon by a clamp  3  that has vertical flanges  4  held together by bolts (not shown). The clamp  3  has tabs  5  that extend outwardly to permit fasteners (not shown) to fasten the tabs  5  and clamp  3  to the panel. This prior art clamp  3  ends up being cast in place within the concrete, once concrete is poured over the form panel  2 . Nails are removed from the tabs  5  by pulling on their pointed ends.  
         [0042]    In FIG. 2 a coupling  6  according to the invention has pre-formed break-away tabs  7  attached to the coupling  6 . While two tabs are shown, only at least one tab is required. Both the coupling  6  and tabs  7  may be molded as a unitary part when the coupling is produced from a molded polymer e.g. PVC, with a thin joining portion  8  which can be broken.  
         [0043]    The break-away tabs  7  have holes through which nails  9  are passed to fix the coupling  7  to a form panel  2 . Once the coupling  7  is cast in place, the breakaway tabs  7  will, upon application of a detaching force separate from the coupling  7  and concrete, along with the nails. Mere removal of the form  2  can achieve this result. The tabs  7  can then be readily removed from the forms.  
         [0044]    In FIG. 3 a detachable fitting  10  is in the form of a collar  11  into which the coupling  12  may be detachably engaged. The collar  11  has a circular flange  13  with holes  14  through which fasteners, e.g. nails  9 , may be passed to engage with a panel  2 .  
         [0045]    As shown in FIG. 6, the coupling  12  has tapered flats  15  which engage with tapered side walls  16  within the bore of collar  11 . The shapes of the flats  15  and the tapered side walls  16  are complementary. The taper angle provides a detachable friction engagement.  
         [0046]    After concrete is poured, the fitting  10  can separate with the removal of the panel  2  from the cast concrete (not shown). In this case, the fitting  10  is a reusable device, e.g. for use on a flying form. Conveniently, the fitting  10  is already in place to be used again at a new location.  
         [0047]    While FIG. 6 shows a cylindrical coupling  12  with tapered flats  15 , the outer surface of the coupling may be fully conically tapered to fit into the bore of a fitting  10  of complimentary shape. The requirement is only that the coupling  12  will separate readily from the fitting  10 , once cast in place, while being retained in place prior to the pouring of concrete.  
         [0048]    As shown in FIG. 7, the standard coupling  17  used today has a wall thickness no greater than the pipe  18  itself  
         [0049]    As shown in FIG. 8, the intumescent coupling requires a thicker wall  20  than the pipe  19  for pipes  50 mm and larger in diameter.  
         [0050]    As shown in FIG. 9, the concrete fill is standardly poured over the coupling and forming plywood  21  to allow machine float finishing  23 . The forming retaining ring  22  is fastened to the plywood form  21 . The intumescent-containing coupling has an increased wall thickness  24  at one end that is especially suited in floor applications. This thickened portion has greater exposure to fire and will intumesce more readily. This is further shown in FIG. 20 where, after removal of the forms and retaining ring, the thickened wall  24  has more exposure to fire  27 .  
         [0051]    A frangible diaphragm pre-positioned on the coupling (as by being integrally molded thereon) serves as a knock out plate  25  to hold back concrete  23  during pouring. As shown in FIG. 10, the knock out plate  25  has been removed, leaving an opening for pipes  26  to enter the coupling.  
         [0052]    As shown in FIG. 11 the gap  29  between the coupling and the concrete wall  33  is lightly or minimally filled with glass wool as a packing  36 . This is for positioning purposes. Such packing  36  is not required to be fully fire resistant because the increased wall thickness of the coupling  30  on intumescing will expand to close the gap  29 .  
         [0053]    On the basis of the foregoing arrangement, a new and more convenient system is provided for positioning in cast-in-place couplings.  
       CONCLUSION  
       [0054]    The foregoing has constituted a description of specific embodiments showing how the invention may be applied and put into use. These embodiments are only exemplary. The invention in its broadest, and more specific aspects, is further described and defined in the claims which now follow.  
         [0055]    These claims, and the language used therein, are to be understood in terms of the variants of the invention which have been described. They are not to be restricted to such variants, but are to be read as covering the full scope of the invention as is implicit within the invention and the disclosure that has been provided herein.