Patent Application
20130055667
The invention is related to a passive fire resistant system for filling a space so that the system resists the spread of a nearby fire through the space. The invention is further related to a prefabricated multilayered structure of such a system for filling spaces or gaps in constructions. The word “passive” intends to reveal that the system does not need to be triggered by anything else other than a rise in temperature due to a nearby fire.
Many constructions, offshore constructions and onshore constructions, comprise purposely designed spaces or gaps in or between construction elements. These spaces or gaps may be formed between ceilings and walls in onshore constructions and facilitate positioning the construction elements relative to each other. The spaces or gaps may have the function of thermally or sound-wise insulating the construction elements from each other. Particularly in steel constructions (both onshore and offshore) such spaces or gaps may also have been designed to allow for differences in thermal expansion between the construction elements. This applied more in particular to so-called “blast-walls” and floors. The spaces and gaps may be relatively large and do sometimes need to be filled by an element that still provides some mechanical stability. Examples can be found between modularly built living units as placed on oil rigs or as used for expanding jails. Such spaces or gaps are designed to be kept free from cables and/or pipes etc. Such a space could, however, be formed by a coaming in a steel construction such as an offshore oil rig or onboard of a vessel, or a window-type space in a stone or concrete wall. It is possible that such a space or gap allows in essence for future incorporation of further infrastructural facilities such as electricity cables, sewage pipes etc. However, it is also possible that such spaces or gaps are always intended to be present and are never intended to be used for transit of further infrastructural facilities. In any case, all such spaces or gaps referred to above are normally required to be sealed off, so that in case of a nearby fire, the fire is not likely to spread through such spaces or gaps throughout the construction. Hence, systems are available for sealing such spaces or gaps in the prior art, also referred to as “openings”.
WO2004/096369 describes a fire resistant material based on an elastomeric foam with a substantially closed-cell structure in which a foam, at least crust-forming fire retardant material and a pH-neutralized graphite material are incorporated. As shown in FIGS. 9 and 10 of WO2004/096369 and as explained in the accompanying description of those figures, particularly page 15 and 16, this material expands upon exposure to heat in the direction which is not directly exposed to the nearby fire. As a result thereof, the sealing is lengthened in a direction in which the temperature decreases. As a result, the material offers longer protection against the effect of fire and/or extreme heat. This material is very suitable for relatively small spaces or gaps. Where the space or gap is large, it cannot offer much mechanical stability.
Particularly, WO2005/078884 describes such a system for sealing an opening in a wall, using first and second fire resistant parts for at least temporary fire resistant sealing of such an opening. The first parts are manufactured substantially from a fire resistant rubber and/or fire resistant thermal plastic. The second parts are manufactured from a fire resistant material based on an elastomeric foam. The first parts are sleeve shaped and comprise a slit for the purpose of being able to place it around the transport device such as a cable, conduit or tube. This system is exclusively dedicated to openings through which a cable, conduit or tube has been fed through. In other words, this system is not suitable for the spaces and gaps for which this disclosure provides a fire resistant system.
It is an object of the invention to provide an improved passive fire resistant system for filling a space or gap for resisting the spread of a nearby fire through that space or gap.
It is a further object of the invention to provide a system that maintains for a much longer period of time during which the system is exposed on one side to a significant rise in temperature, the low temperature at the side which is not exposed to the nearby fire.
It is a further object of the invention to provide a system which demonstrates after cooling down of the side exposed to a nearby fire, water tightness of that system against a stream of water used for extinguishing the fire.
The invention provides a passive fire resistant system for filling a space or gap confined by construction elements, for resisting the spread of a nearby fire through the space or gap. The system comprises at least two first layers of a first material which comprises a fire resistant elastomeric foam having a closed-cell structure. The system further comprises at least one second layer of a second material sandwiched between the two first layers. The second material comprises a polymer and each second layer has surfaces which, as an initial response to a rise in their temperature from room temperature, exhibits a transition into an adhesive. These first and second layers extend parallel to each other. The second material is stiffer than the first material.
Without wishing to be bound by any theory, it is strongly believed that as a result of a nearby fire, i.e. due to a rise in temperature, initially the surfaces of the second material become adhesive so that the first and second layers at their contact surfaces stick firmly to each other. Although, as a consequence of the rise in temperature, the gas pressure in the closed cells of the elastomeric foam increases, expansion of these closed cells is suppressed by the adhesion of the elastomeric foam close to the second layers to the second material. This suppression is possible as the second material is much stiffer than the first material. The much stiffer second material imposes thus a counterforce onto the expanding elastomeric foam. As the expansion of the closed cells is suppressed, a bursting pressure of these cells is not reached. The insulating capacity of the fire resistant system is consequently maintained for a larger period of time. As, initially, the expansion of the fire resistant elastomeric foam is suppressed, and insulating properties are well maintained, the passive fire resistant system remains at a side that is not exposed directly to a nearby fire, much longer in its original state. As the temperature deeper into the multi-layered structure remains low, also the mechanical stability offered by the system, and further elaborated on below, continues to be unaffected.
In an embodiment of a system according to the invention, the at least one second layer is adhesively sandwiched between two first layers by adhesive contact of the second layer with each of these first layers. Advantageously, at least three layers can as one unit rapidly and conveniently be placed in the space that needs to be filled with the passive fire resistant system. It is even possible to make a multi-layered structure of first and second layers in a size such that by placement of one unit of such a multi-structure the space is directly filled up with the passive fire resistant system.
In an embodiment of a system according to the invention, each first layer is sandwiched between two second layers of the second material. This has the advantage that a number of the outer layers of the passive fire resistant system are always of the second material. Upon increase of the temperature, the outer surfaces of these second layers will exhibit the transition into an adhesive and as such adhere the passive fire resistant system as placed in the space against the inner wall of that space. This will provide an additional “cage” in which the passive fire resistant system will then be held, providing an additional counter-pressure against expansion of the elastomeric foam. In other words, it further contributes to maintaining the original state of the passive fire resistant system in that space, particularly maintaining the closed state of the cells in the elastomeric foam.
In an embodiment of a system according to the invention, each first layer is adhesively sandwiched between two second layers of the second material by adhesive contact of the second layers with the first layers. Also in this embodiment, it is advantageous that the outer layers are already fixed to the main body of layers so that the passive fire resistant system for filling a space can be considered a fully pre-fabricated unit that significantly reduces the time needed for installing the passive fire resistant system in such a space.
In an embodiment of a system according to the invention, the adhesive contact is a result of preheating a surface of a second layer, pressing that preheated surface against a surface of the first layer, and then letting the surfaces, which are pressed against each other, cool down. Advantageously, use is made of the nature of the second layer in the preparation of such a multi-layered structure. As will further be described below in a more detailed description, of the invention, such a multi-layered structure can act as a so-called bridge bearing, which can carry loads of 12000 kg per m2.
In an embodiment of a system according to the invention, the polymer is a cross-linkable polymer. This allows for a further improvement of the mechanical properties of the second material. In essence, the second material may then as a result of a further rise in temperature adopt a rubber-like nature, and as such improves it stiffness. Consequently, it remains possible for the second material to continue suppressing expansion of the fire resistant elastomeric foam. Preferably, the second material comprises a vulcanizing agent that is activated at a temperature above 140° C.
In an embodiment of a system according to the invention, the second material comprises at least one component that causes the second material to thermally expand in a relatively low predetermined temperature range, of which a lowest temperature is above a temperature at which the transition into an adhesive is exhibited. Advantageously, the counter-pressure provided by the second material against the expansion of the fire resistant elastomeric foam can be maintained and even enhanced when the system is exposed to high temperatures. In other words, when the temperature rises and the pressure in the closed-cell structures increases and comes close to the bursting pressure of these closed cells, the second material will more strongly suppress such expansion of the closed cells, as the second material will expand itself. It follows that the insulating capacity of the system can be maintained for a longer period of time, even under the thermally more severe conditions.
Preferably, the at least one component is a thermally expandable graphite. That graphite is preferably a pH-neutralized graphite.
The invention further provides a multi-layered structure for filling a space or gap confined by construction elements, for resisting the spread of a nearby fire through the space or gap and for providing mechanical stability between the construction elements. The structure comprises: at least two first layers of a first material which comprises a fire resistant elastomeric foam having a closed-cell structure; and at least one second layer of a second material adhesively sandwiched between two first layers so that the first and second layers extend parallel to each other. The second material comprises a polymer and is stiffer than the first material.
The multi-layered structure is a prefabricated passive fire resistant system which offers the advantage the layering itself does not have to take place at the construction site. This prefabricated multi-layered structure offers immediately the mechanical stability as it does not have to be built up layer by layer. Furthermore, there is no need to wait for a nearby fire, or to deliberately apply heat locally, to ensure that the second layer sandwiched between the first layers will adhesively bond to these first layers. The manufacturer of the multi-layered structure will, under carefully controlled circumstances, have ensured that optimal bonding between these layers has already taken place. It is possible to cut the prefabricated multi-layered structure on a construction site, so that it will be locally tailored for fitting in a space or gap of concern. However, it is of course also possible that the manufacturer produces the multi-layered structures in a predescribed dimension, so that even any cutting can be avoided at the construction site.
Such a multi-layered structure can act as a bridge bearing, and carry a load of 12000 kg per m2, and accept a compression of about 40% without failure of the multi-layered structure.
The invention will be further explained with reference to the non-limiting drawing, which shows in:
In the drawing like parts are referred to by like references.
The phrase “having a closed-cell structure” is understood to mean a cell structure in which at least 60%, but more preferably at least 75% of the cells are closed. This provides good thermal insulation.
The system further comprises a number of second layers 4 of a second material. The first and second layers 3, 4, extend parallel to each other. The second material comprises a polymer and each second layer 4 has surfaces which, as an initial response to a rise in their temperature from room temperature, exhibit a transition into an adhesive. The second material is stiffer than the first material. An example of the second material is described in WO2009/090247, in which the second material is described as the material of which a device is made, referred to in WO2009/090247 as device 6. the Applicant sells that material under the trade name RISE Ultra. The polymer is preferably a cross-linkable polymer. The polymer may be an EPDM, or preferably an ethylene acetate polymer (EVA). The second material preferably comprises a vulcanizing agent that is activated at a temperature above about 140° C.
As shown, it is possible that also each first layer 3 is sandwiched between two second layers 4 of the second material. In this respect,
Also the first material may comprise at least one component that causes the first material to thermally expand in a relatively high predetermined temperature range, of which the lowest temperature is above a temperature at which the surfaces of the second material exhibit a transition into an adhesive and is about at the temperature at which the vulcanizing agent is activated. Such a component may for both the first material and the second material be a thermally expandable graphite, which can be commercially obtained for expansion within different temperature ranges. The graphite is preferably pH-neutralized graphite. The first material may further comprise at least one crust-forming fire retardant component, for example, melaminephosphate. For possible compositions of the first material, reference is further made to WO2004/096369.
Each of the first layers has a thickness within the range varying from 1-4 cm, preferably within a range varying from 2-3 cm, even more preferably is about 2.5 cm. As shown, the thickness is preferably constant along the first layer. It is possible to make first layers for instance with a thickness of 1 cm, 1.5 cm, 2.0 cm, etc.
The second layer has preferably a thickness within the range varying from 1-4 mm, preferably from 2-3 mm, and even more preferable is about 2.5 mm.
In the event of a nearby fire, the temperature on the side of the wall closest to that nearby fire will rise. It is expected that the fire resistant system will be heated up by the hotter air. This will form the main source of heat input into the fire resistant system. In other words, heat transfer from the wall to the fire resistant system is considered to be negligible in this case.
The fire resistant system, particularly due to the cell structure in the first material will provide excellent heat insulation and inhibits the transfer of heat from the side exposed to the nearby fire to the side of the wall further away of the nearby fire. Further below, the side which is more directly exposed to the nearby fire is referred to as the exposed side. The side not directly exposed to the nearby fire, is further down referred to as the “unexposed side”.
Due to the rise in temperature the surfaces of the second layer will exhibit a transition into an adhesive and as such become adherent to the surfaces of the first layer. Although the heated gas in the closed cells will cause the pressure in those cells to rise, expansion of those cells, let alone bursting of the cells, will be suppressed by the adhesion of cells to the stiffer second layer. In other words, as the second material is stiffer than the first material, any deformation of the first material close to positions where the second material adheres to the first material will be suppressed. This lack of deformation of cells adhering to the second layer is in effect illustrated in
As explained, expansion of the closed cells in the first material, is counteracted, to an extent. The bursting pressure of the cells is unlikely to be reached and the perfect insulation formed by the first material will continue to be present. As the first material remains in an insulating state, the layers of the second material, particularly “deeper” into the system, will not increase much further in their temperature and thus remain stiff. The mechanical stability is thus also maintained.
The upper end bottom second layer and the vertically positioned layers 4a may reach a temperature at which the transition into an adhesive occurs. This ensures that the system will be “glued” into the opening.
Even though a response of the passive fire resistant system concerns a mechanism that aims at maintaining the state of the system, a part of the system that is more directly and closely exposed to a nearby fire, i.e. the part that is not insulated from the nearby fire, will experience a very high rise in temperature. Due to the crust-forming fire retardant component in the first material, such a crust will however be formed at the exposed side of the fire resistant system. At such high temperatures, also the thermal expansion of the second material will take place. The second material expands toward the heat source, offering further protection for the passive fire resistant system, between the layers of the crust formed by the first material.
The inventor found after exposure for more than one hour to a nearby fire that the temperature of the fire resistant system at the unexposed side, had only risen by 2° C. On the exposed side, a couple of mm of char had been formed. When the exposed side was then subjected to a so-called regular hose stream test (a 6 bar water hose stream directed at the passive fire resistant system at the exposed side) from a predescribed distance of 6 m, there was not any leakage of water through the passive fire resistant system from the exposed side to the unexposed side. Applying a more severe hose stream test from only 4 m distance with full load resulted in removal of the char layer of the fire resistant system. The passive fire resistant system could only be removed as a single unit by cutting it out of the opening in the wall, as all layers had clearly laminated to each other, particularly at the exposed side.
There is a direct route formed by hot gas directly “contacting” the passive fire resistant system, and an indirect route formed by transfer of heat from the equally heated metal coaming 5 and metal wall 6 into the passive fire resistant system. The most upper, most lower and vertical second layers 4a, particularly toward the exposed side, reach a temperature that is far higher than the temperature at which the transition into an adhesive occurs. At those positions, the second material starts to thermally expand and starts to form a cross-linked material as the vulcanizing agent will have been activated. This phenomenon may clamp the system with the space or gap and suppress the expansion of the first material. Again, at the side that is directly exposed to heat, i.e. that is not insulated by the fire resistant itself, the second material will expand toward the source of heat, and the first material will form a crust. However, the temperature reached at positions deeper within the fire resistant system is higher than the temperature reached for the fire resistant system placed in a wall 1 as discussed above in relation to
The second material comprises polymer and is stiffer than the first material. As explained, in this example, each second layer is adhesively sandwiched between two first layers 3 by adhesive contact of the second layer 4 with each of these first layers 3. A number of first layers 3 are equally adhesively sandwiched between two second layers 4 of the second material. Those first layers 3 are adhesively sandwiched between two second layers 4 of the second material by adhesive contact of these second layers 4 with the first layer 3. The adhesive contact discussed above may be a result of preheating a surface of a second layer, pressing that preheated surface against a surface of a first layer 3 and then letting these surfaces which are pressed against each other cool down. The first layers 3 and the second layers 4 are as those described in relation to
Also, such a prefabricated multi-layered sandwich structure is preferably applied with second layers at the top and the bottom as well as sideways oriented in a vertical direction (see for example
In summary, both the passive fire resistant system as well as the prefabricated multi-layered sandwich structure are applied with these extra second layers of second material at the bottom and at the top, as well as sideways in a vertical direction. So far, this has been to deliver an optimal effect. The second layers of second material within the multi-layers are thermally insulated, so that the mechanical stability at those positions is maintained. The layers at the bottom, top and sides of the system and structure are, particularly at the exposed side, not thermally insulated, and will turn into an adhesive, fixing the system and structure within the spaces or gaps against the construction elements by which these spaces or gaps or confined. Parts of the system and structure that are directly exposed to a high rise in temperature trigger the crust formation of the first material and the thermal expansion of the second material toward the heat source. It forms a relatively thin but effective shield, ensuring that the part of the system and the structure further away from the heat sources and insulated by the system and structure itself, maintain their original mechanical and thermal insulation properties.
The invention is not limited to the examples and embodiments discussed above. Alterations and modifications are possible. It is, for instance, possible to design a multi-layered structure, to be prefabricated or to be put together on the construction site, wherein the first layers have a thickness that varies with their position within the structure and wherein the second layers have a thickness that varies with their position within the structure. The contribution of the various layers can then be optimized so that the overall response of the system even further meets the objectives outlined earlier on.
Such alternative embodiments are each understood to fall within the framework of the invention as defined by the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 09177341.6 | Nov 2009 | EP | regional |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2010/057128 | 5/25/2010 | WO | 00 | 11/20/2012 |
