Non-metallic fire protection and insulation wall for structures

Abstract

The present invention pertains to the field of modular data centres, more specifically to the structural field of data centres, such as non-metallic walls that clad the structures of the modular data centre system. The present document proposes the development of a non-metallic wall capable of being installed under adverse weather conditions and of providing protection against extreme hazards, such as fire, while still ensuring the safety and full operation of the data centre. The main advantages of the non-metallic wall include mechanical strength thereof, which, in addition to ensuring sealing against the ingress of water and dust, also provides robustness in order to prevent attempted break-ins or acts of vandalism. The non-metallic wall developed further aims to be a low-cost solution that solves the prior art problem of providing a robust module for a modular data centre.

Description

[0001] NON-METALLIC FIRE PROTECTION AND INSULATION WALL FOR STRUCTURES FIELD OF THE INVENTION

[0002]

[0001] The present innovation belongs to the area of ​​Mechanical Engineering, in its technological aspect of modular infrastructure, more specifically, in non-metallic walls developed for the structures of the modular data center system, but not limiting the invention to this single field, since this product can be applied in the most diverse technological areas of Engineering.

[0003] BACKGROUND OF THE INVENTION

[0004]

[0002] The demands for data storage and control have become increasingly important for all segments of industries, companies, offices, shopping malls, businesses, and even leisure environments; all the technology applied in these solutions has a data center behind its operation.

[0005]

[0003] Data centers are installed in environments with very specific characteristics in order to guarantee their performance and avoid failures that could jeopardize the operation of the modular data center system. These characteristics include the control of a wide variety of psychrometric conditions, such as temperature, humidity, cooling, heating, water vapor, etc.

[0006]

[0004] In addition to the internal characteristics, it is also necessary to ensure the external security of the modular data center system, that is, the structure used for the non-metallic walls of the modular data center system must be protected against various weather conditions, such as dust, rain, and even more extreme conditions such as fire. Furthermore, this solution must be secure enough to prevent the possibility of break-ins or intrusion by unauthorized persons.

[0007]

[0005] Aiming to obtain a solution that resolves the technical problem listed above with all its adversities, this document describes a non-metallic wall, with sufficient security to protect the modular data center system against the most adverse weather conditions, including protection against fire, as well as being a secure solution against any type of break-in or attempted entry by unauthorized persons. Furthermore, it is capable of ensuring that the non-metallic wall withstands the most critical conditions, such as being directly exposed to a fire external to the modular data center system, and still guaranteeing that this fire cannot reach the interior of the data center, thus maintaining its full operation without damage or risk of interruption.Alternatively, the solution also features a complex sealing system that allows the non-metallic wall to be used in outdoor areas directly exposed to the elements, such as sun, rain, dust, strong winds, sea spray, and other abrasive elements, without risk of causing any damage to the internal parts of the modular data center system.

[0008]

[0006] Several solutions have been developed seeking to optimize and improve data centers, given the extensive use of this equipment.

[0009]

[0007] Aiming at the construction of a fireproof partition wall, in 2022, the unionist priority of patent application WO2023243150, which includes patent application BR 11 2024022141-5, entitled “FIREPROOF PARTITION WALL”, proposed as a solution two gypsum walls that are joined by metal pins, and that are capable of withstanding fire for one hour. Although sharing part of the scope of the innovation present in this document, patent application WO2023243150 does not exhibit weather resistance, does not withstand at least two hours of exposure to fire, and has a constructive solution entirely distinct from the solution developed in the present innovation.

[0010]

[0008] Patent application WO2019124505, with a priority date of 21.12.2017, whose patent family includes patent BR 11 2020011530-4, entitled “FIREPROOF COVERED STRUCTURE FOR PENETRATION PART” proposed as a solution a fireproof covering formed by layers of commercially available gypsum boards, arranged in the thickness direction, in order to form a portion over a wooden construction that is fireproof. Although its scope is partially the same as the scope of this document, the solution differs from the solution developed in this document because it presents other characteristics within its scope, such as protection against weathering, and would not meet these requirements if only a stacking of gypsum boards were used, since it is known in the state of the art that gypsum does not have resistance to water or exposure to other types of weather such as sun, dust, sea air, or chemical components.

[0011]

[0009] In 2002, patent application PI 0204390-4, entitled “FIRE DOOR”, proposed a solution consisting of a wall with a metal sheet frame and a plasterboard core. Although patent application PI 0204390-4 also partially shares the scope of this document, the solution differs from the solution developed in this document, which also includes the following characteristics: protection against weathering, such as rain, sun, dust, and sea air; as well as protection against oxidation and corrosion. Patent application PI 0204390-4, in addition to not fully meeting the scope of this document, since it is known in the state of the art that plaster does not have resistance to water or exposure to other types of weathering such as sun, dust, sea air, or chemical components, also proposed a constructive configuration entirely distinct from the innovation detailed in this document.

[0012]

[0010] In short, none of the documents available in the state of the art proposed the development of a non-metallic wall capable of guaranteeing safety, protection against fire, water, dust, sea spray or contaminants, through a robust and meticulously developed non-metallic wall to guarantee uninterrupted operation in accordance with the most demanding standards of the international market.

[0013]

[0011] For the development of the non-metallic wall for the modular data center system, it was necessary to develop specific components which will be detailed in this document.

[0014] OBJECTIVES OF THE INVENTION

[0015]

[0012] The present innovation aims to develop a non-metallic wall capable of protecting the environment in which it will be installed from any adverse weather conditions.

[0016]

[0013] The solution also aims to ensure the safety and integrity of the environment in which the non-metallic wall is installed.

[0014] Furthermore, the innovation developed also aims to provide robust insulation of the external environment from the internal environment, even in extreme fire conditions.

[0017]

[0015] The developed non-metallic wall is a modular solution, therefore it has the versatility to be installed in the most diverse structures, used in various fields of application, as long as they have the demand for protection, security, impermeability, weather resistance and other characteristics of the developed non-metallic wall.

[0018] BRIEF DESCRIPTION OF THE FIGURES

[0019]

[0016] In order to facilitate understanding of the non-metallic wall developed in the present invention and its application in a modular data center system, this patent includes the figures described below:

[0020]

[0017] Figure 1 shows the front perspective view of the modular system.

[0021]

[0018] Figure 2 shows the front perspective view of the first configurable variant of the modular system, presented in Figure 1.

[0022]

[0019] Figure 3 shows an enlarged front perspective view of the electrical room of the modular system, shown in Figure 1.

[0023]

[0020] Figure 4 shows an enlarged front perspective view of the lower module of one of the rooms in the modular system shown in Figure 1.

[0024]

[0021] Figure 5 shows an enlarged front perspective view of the non-metallic wall used in the rooms of the modular system.

[0025]

[0022] Figure 6 shows an enlarged front view of the non-metallic wall used in the rooms of the modular system.

[0026]

[0023] Figure 7 shows an enlarged rear view of the non-metallic wall used in the rooms of the modular system.

[0027]

[0024] Figure 8 shows an enlarged front perspective view of the non-metallic wall used in the rooms of the modular system, with the components assembled in exploded position.

[0028]

[0025] Figure 9 shows an enlarged front perspective view of the isolated structure of the non-metallic wall assembly used in the rooms of the modular system.

[0026] Figure 10 shows an enlarged front view of the isolated structure of the non-metallic wall assembly used in the rooms of the modular system, with sections AA and BB indicated.

[0029]

[0027] Figure 11 shows an enlarged top view of the isolated structure of the non-metallic wall assembly used in the rooms of the modular system, projected through section AA.

[0030]

[0028] Figure 12 shows an enlarged right side view of the isolated structure of the non-metallic wall assembly used in the rooms of the modular system, projected through section BB.

[0031]

[0029] Figure 13 shows an enlarged front perspective view of the isolated external panel of the non-metallic wall assembly used in the rooms of the modular system.

[0032]

[0030] Figure 14 shows an enlarged front perspective view of the isolated inner panel of the non-metallic wall assembly used in the rooms of the modular system.

[0033] DESCRIPTION OF THE INVENTION

[0034]

[0031] The non-metallic wall developed in the present invention aims to solve the technical problem of non-metallic walls that lack fire protection, exposing the rooms of the modular data center system to the risk of damage in case of fire and also depend on an extra fire suppression system, without guaranteeing the protection and integrity of the rooms, in order to prevent the fire from causing damage to the equipment inside the rooms.

[0035]

[0032] Another problem with the prior art is that walls lack weather protection and depend on an extra module to provide such protection, such as a masonry structure large enough to prevent the elements from reaching the prior art walls, which lack weather protection.

[0036]

[0033] Another problem with the state of the art concerns the physical security of the solution. Because it involves high-cost equipment and also because it stores customer data on computer equipment, it is extremely important that the non-metallic wall solves the technical problem of lack of protection against break-ins and unauthorized access to the environment. In other words, the solution must be robust enough to prevent break-ins or theft attempts, among other problems related to the security of the environment.

[0037]

[0034] In order to show how the solution is used in the structure of a modular data center system, Figure 1 presents a front perspective view of the modular data center system. In this view, it is possible to visualize the data room, the cooling room, the electrical room, and the redundant electrical rooms. Figure 1 also indicates the orthogonal axes X, Y, and Z. The X-axis indicates the longitudinal direction of the structures, a dimension also known as the length of the structures; the Z-axis indicates the transverse direction of the structures, a dimension also known as the width of the structures; and finally, the Y-axis indicates the direction parallel to the height of the structures.

[0038]

[0035] The previous perspective view, illustrated in Figure 2, shows another configuration for a modular data center system, which consists of two data rooms, two cooling rooms, one electrical room and two redundant electrical rooms, and a telecommunications room, which is not visible in this figure. Other alternative configurations can be used, since one electrical room and two redundant electrical rooms are capable of serving different numbers of data rooms, up to 12 data rooms, depending on the total capacity demanded by the modular data center system. And, in all these rooms, the non-metallic wall developed in this innovation is used.

[0039]

[0036] In order to show how the solution is assembled in the structure that uses the non-metallic wall, Figure 3 is presented, which is a front perspective view of the electrical room, preferably used in a modular data center system. This figure allows visualization of how the non-metallic wall is mounted in the room structure and is in contact with the external area.

[0040]

[0037] In figure 4 it is possible to visualize the front perspective view of one of the modules of one of the rooms, of the modular data center system, in which the developed non-metallic wall is also used, and in this case the non-metallic wall is also in contact with the external area.

[0041]

[0038] Figure 5 shows an enlarged front perspective view of the non-metallic wall used in the rooms of the modular system, shown in Figures 1, 2, 3 and 4.

[0039] The enlarged front view illustrated in Figure 6 shows the non-metallic wall developed in this document. In this view, it is possible to see the face of the non-metallic wall that is in contact with the interior of the room where the non-metallic wall is installed; this is why the mounting points of the non-metallic wall are located on this face, so as not to allow access to these mounting points from the outside.

[0042]

[0040] The enlarged rear view, illustrated in Figure 7, shows the non-metallic wall developed in this document. In this view, it is possible to see the face of the non-metallic wall that is in contact with the external environment of the room where the non-metallic wall is installed. This is why the mounting points of the non-metallic wall are not visible on this face, so as not to allow access to these mounting points from the outside.

[0043]

[0041] The enlarged front perspective view, illustrated in Figure 8, shows the non-metallic wall used in the modular system rooms, with the components assembled in exploded view. Also in Figure 8, each of the components used in the assembly of the non-metallic wall is identified with its respective numerical references: the structure; the outer panel; the inner panel and the blanket.

[0044]

[0042] The enlarged front perspective view shown in Figure 9 shows the structure, isolated from the non-metallic wall assembly, used in the modular system rooms.

[0045]

[0043] The enlarged front view, illustrated in Figure 10, shows the structure, isolated from the non-metallic wall assembly, used in the modular system rooms. Figure 10 shows the details of the joint between the components that form the structure. The assembly of these components can be carried out by different manufacturing processes, without restricting the process to the innovation developed. Thus, assembly can be carried out using fasteners, welding, or other processes. Also in Figure 10, sections AA and BB are identified to allow visualization of the details of the components that make up the non-metallic wall structure.

[0046]

[0044] The enlarged top view, illustrated in Figure 11, shows the isolated structure of the non-metallic wall assembly used in the rooms, of the modular system, designed through section AA. In this view, it is possible to visualize how the components fit together to form a rigid structure that guarantees the protection and safety of the developed non-metallic wall. In this view, we have the preferred solution of assembling the components that form the structure through the use of fasteners, and in this structure, in the horizontal position, i.e., in the direction of the X and Z axes, we have seven sets of fasteners.

[0047]

[0045] The enlarged right side view shown in Figure 12 shows the isolated structure of the non-metallic wall assembly used in the rooms of the modular system, projected through section BB. In this view we have the preferred solution for assembling the components that form the structure, through the use of fasteners, and in this structure, in the vertical position, i.e., in the direction of the Y axis, we have two sets of fasteners.

[0048]

[0046] The enlarged front perspective view illustrated in Figure 13 shows the isolated outer panel of the non-metallic wall assembly used in the rooms of the modular system. The outer panel is the component of the non-metallic wall that interfaces with the external environment where the room of the modular data center system is installed. This is why the wall mounting points are not visible on this face, so as to prevent access to these mounting points from the outside, in order to guarantee the security and protection of the room where the non-metallic wall is installed. Mounting the non-metallic wall on its inner face prevents attempts at break-ins or vandalism, since no mounting element is accessible from the outside.

[0049]

[0047] Figure 14 shows an enlarged front perspective view of the isolated inner panel of the non-metallic wall assembly used in the rooms of the modular system. The inner panel is the component of the non-metallic wall that interfaces with the internal environment where the room of the modular data center system is installed. In Figure 14, it is possible to visualize the fastening elements used in the wall assembly, since this assembly is carried out on the inner face of the wall, which is precisely the inner panel.

[0050]

[0048] The developed non-metallic wall solution preferably has a thickness between 70 and 140 mm, more specifically between 80 and 130 mm, with a thickness of 90 mm providing at least 120 minutes of fire resistance. The non-metallic wall consists of a structure that is externally covered by an outer panel and internally by an inner panel. The space between the structure and the outer panel is filled with insulation to provide fire protection. Alternatively, sealants, sealants, and intumescent paint can be applied to the outer face of the outer panel, providing protection against water and dust ingress, and against fire, allowing the non-metallic wall to be installed in outdoor environments. The space between the structure and the inner panel is also filled with insulation to increase fire protection. Furthermore, the internal assembly ensures protection against vandalism.

[0051]

[0049] The non-metallic wall developed in the present invention consists of an outer layer of board, preferably cementitious, whose thickness may vary from 5 to 20 mm, although it is even more recommended that the thickness vary from 8 to 16 mm; this component is designated as the outer board (10.2). An inner layer of board, preferably gypsum board, may vary from 8 to 22 mm, although it is even more recommended that the thickness vary from 10 to 20 mm; this component is designated as the inner board (10.3). The interior between the outer board (10.3) and the structure (10.1) is filled with insulating material of the blanket type, preferably ceramic fiber blanket, with a density between 30 and 160 kg / m³. 3 more preferably between 50 and 140 kg / m². 3 The interior between the inner plate (10.2) and the structure (10.1) is also filled with insulating material of the blanket type, preferably ceramic fiber blanket, with a density between 30 and 160 kg / m³. 3more preferably between 50 and 140 kg / m². 3 , where, at a density of 64 kg / m³ 3 The non-metallic wall can withstand a minimum of 120 minutes of fire without causing any damage to the room's interior. This configuration, when exposed to fire, remains intact and transmits a low amount of heat from one side to the other, thus protecting people and equipment.

[0052]

[0050] The construction of the non-metallic wall of the modular data center system, made with a combination of different raw materials and with a central structure, preferably in steel, allows the rooms of the modular data center system to be transported without causing damage to the structure, since the elasticity of the steel used in the central structure contributes to non-permanent deformations.

[0051] The construction of the non-metallic walls also solves the issue of the integrity and security of the environment, thus hindering acts of vandalism and attempted intrusions.

[0053]

[0052] In addition to fire protection, the thermal insulation, in this case the blanket, reduces heat exchange between the internal environment of the modular data center system and the external environment, improving the efficiency of the air conditioning system of the modular data center system.

[0054]

[0053] The inner face is preferably constructed of plaster, and because it is fixed to a steel structure, it allows objects such as panels, pipes, structures, gutters, conduits and light fixtures to be fixed directly to it.

[0055]

[0054] The construction of the non-metallic wall (10) uses a structural frame, designated as structure (10.1), normally constructed from bent profiles, metal bars or beams, preferably using “U” and “C” profiles.

[0056]

[0055] The versatility of this non-metallic wall (10) allows it to be mounted in panels or built directly into the room structure, of the modular data center system (1).

[0057]

[0056] With all the features detailed above, the non-metallic wall solution (10) contributes to fire protection, weather protection, vandal protection, improved transportability, and improved air conditioning system efficiency.

[0058]

[0057] The modular data center system (1) is preferably developed using the following components: data room (2), cooling room (3), electrical room (4), redundant electrical rooms (5) and telecommunications room (6).

[0059]

[0058] The non-metallic wall (10) developed in this document was preferably developed using the following components: structure (10.1); outer plate (10.2); inner plate (10.3) and blanket (10.4).

[0060]

[0059] The structure (10.1) is the central structure of the non-metallic wall (10), which is preferably assembled with metallic material, but may alternatively be manufactured by welding process, or by assembling folded sheets, angles, tubes or beams and may also alternatively be manufactured in other non-metallic raw materials, provided that such raw materials meet the dimensioning of the necessary mechanical resistance and also the fire resistance requirement.

[0061]

[0060] The external panel (10.2) is the external structure that directly receives contact with fire in the event of an occurrence in the external area of ​​the non-metallic wall (10), mounted in the room, of the modular data center system (1). The external panel (10.2) is preferably manufactured with cementitious board, since this raw material has good resistance to weathering, and is the closest possible way to equate a modular data center system to traditional data centers built in common masonry. The external panel (10.2) also has the function of protecting and isolating the blanket (10.4), in addition to being responsible for protection against water ingress from the outside of the non-metallic wall (10).

[0062]

[0061] The inner plate (10.3) is the face that comes into contact with the internal environment of the room, of the modular data center system (1). The inner plate (10.3) is assembled with fastening elements, such as screws, rivets, etc., in order to guarantee the rigidity of the assembly between the inner plate (10.3) and the structure (10.1). The inner plate (10.3) also has the function of protecting and isolating the blanket (10.4).

[0063]

[0062] The blanket (10.4) is the thermal insulating material that, in case of fire, retains thermal energy, preventing heat from fully passing through the non-metallic wall (10) and reaching the internal environment of the room, of the modular data center system (1), in which the non-metallic wall (10) is mounted.

[0064]

[0063] The non-metallic wall (10) is required to overlap the entire external structure of the room, of the modular data center system (1), in order to guarantee security requirements, mainly to prevent break-in or vandalism attempts.

[0065]

[0064] The structure (10.1) is alternatively manufactured from folded steel in order to meet the requirements of mechanical strength, to ensure robustness and security against attempted break-ins and thefts.

[0066]

[0065] Alternatively, the seal used between the installation of the external panels (10.2) reinforces protection against water ingress and also protects against the ingress of dust and other contaminants. This seal is preferably round and made of ceramic fiber material, in order to also provide fire resistance.

[0067]

[0066] A second seal may be used to protect against the entry of water, dust and contaminants. The geometry of this seal contributes to the impermeability of the non-metallic wall (10) along with its raw material which is preferably made of silicone with a high melting point, in order to also withstand fire conditions.

[0068]

[0067] Alternatively, the external coating applied to the external plate (10.2) aims to protect the external face of the non-metallic wall (10) against weathering, in order to avoid damage to the non-metallic wall (10) by chemical attack that may cause the oxidation and / or corrosion process, or even protection against wear from direct exposure to weather conditions, such as sun and rain, or even sea air.

[0069]

[0068] Alternatively, in order to increase the fire protection capacity of the room, a sealant may be used to install the seals described above, in order to reinforce protection against the entry of water and dust.

[0070]

[0069] Alternatively, in order to increase the fire protection capacity of the room, an alternative solution may include applying a protective coating to the internal and external surfaces, such as intumescent protection, which is a second layer of fire protection, and can be applied to the external panel (10.2) for protection against fire coming from the outside area and can also be applied to the internal panel (10.3) to contain the fire inside the room. The intumescent protection aims to ensure the integrity of the non-metallic wall (10) during a fire condition, or direct exposure to fire. Under temperatures above 750°C, the protection begins to intumesce in order to form a physical barrier on the external surface of the external panel (10.2), and on the internal surface of the internal panel (10.3), this barrier has a thickness of approximately 50 mm, and provides insulation before the heat reaches the seal.

[0071]

[0070] The blanket (10.4) is a thermal insulator that helps ensure that the non-metallic wall (10) can withstand extreme fire conditions. The blanket (10.4) has specific resistance characteristics for very high temperatures, being designed to withstand temperatures above 1200°C.

[0071] In order to ensure the performance of the entire assembly that forms the non-metallic wall (10), an exposure test was carried out at temperatures up to 1200°C for a sufficient time to guarantee 300% performance above the normative requirements for testing the non-metallic wall (10), and after the test all structural components remained intact and the intumescent protection formed the expected insulation barrier.

[0072]

[0072] It is important to highlight that the non-metallic wall (10) developed can also, alternatively, be applied in the most diverse buildings that have the demand for the requirements described in the present solution, such as industrial buildings, commercial buildings, vault rooms and even for containers used as a fixed structure, for the most diverse applications.

[0073]

[0073] As we adjust the profile settings and increase the thickness of the non-metallic wall (10) by filling it with more blanket (10.4) we are able to increase the fire resistance time, allowing alternative non-metallic wall (10) solutions to meet more demanding safety requirements.

[0074]

[0074] The non-metallic wall (10) developed is required to: have protection against water ingress; against dust ingress and against the ingress of contaminants from the outside to the inside of the modular data center system (1); have airtightness against the passage of gases or smoke; have thermal insulation; and have protection against fire from the outside to the inside of the modular data center system (1), and withstand temperatures above 750°C, preferably above 1200°C. The wall (10) developed also provides for a security system against break-ins and vandalism.

Claims

CLAIMS 1. NON-METALLIC FIRE PROTECTION AND INSULATION WALL FOR STRUCTURES characterized in that the wall (10) is formed by the structure (10.1), the outer plate (10.2), the inner plate (10.3) and the blanket (10.4), wherein the outer plate (10.3) is fixed to the outer face of the non-metallic wall (10); wherein the inner plate (10.3) is fixed to the inner face of the non-metallic wall (10); wherein the outer plate (10.2) and the inner plate (10.3) are fixed to the structure (10.2); wherein the blanket (10.4) is installed between the structure (10.1) and the outer plate (10.2); wherein the blanket (10.4) is installed between the structure (10.1) and the inner plate (10.3).

2. NON-METALLIC FIRE PROTECTION AND INSULATION WALL FOR STRUCTURES, according to claim 1, characterized in that the structure (10.1) is preferably made of thin metallic material; the outer plate (10.2) is preferably made of cementitious material; the inner plate (10.3) is preferably made of gypsum; and the blanket (10.4) is preferably made of thermal insulating material.

3. NON-METALLIC FIRE PROTECTION AND INSULATION WALL FOR STRUCTURES, according to claims 1 and 2, characterized in that the inner plate (10.3) is the face that is in contact with the internal environment of the room, and is mounted with fastening elements; the outer plate (10.2) is the face that is in contact with the external environment of the room.

4. NON-METALLIC FIRE PROTECTION AND INSULATION WALL FOR STRUCTURES, according to claim 1, characterized in that, alternatively, a seal, preferably made of ceramic fiber, may be used between the installation of the outer plate (10.2) and the inner plate (10.3), and a second seal, preferably made of silicone.

5. NON-METALLIC FIRE PROTECTION AND INSULATION WALL FOR STRUCTURES, according to claims 1 and 4, characterized by, alternatively, the use of a sealant in the installation of the walls.

6. NON-METALLIC FIRE PROTECTION AND INSULATION WALL FOR STRUCTURES, according to claim 1, characterized in that, alternatively, the outer plate (10.2) and the inner plate (10.3) receive an outer coating for protection against corrosion, oxidation and weathering.

7. NON-METALLIC FIRE PROTECTION AND INSULATION WALL FOR STRUCTURES, according to claim 1, characterized in that, alternatively, the structure (10.1) can be manufactured with folded sheets, welded sheets, angle bars, tubes or beams.

8. NON-METALLIC FIRE PROTECTION AND INSULATION WALL FOR STRUCTURES according to claim 1, characterized by, alternatively, an intumescent coating being applied to the internal and external surfaces of the wall (10) of the modular data center system (1).

9. NON-METALLIC FIRE PROTECTION AND INSULATION WALL FOR STRUCTURES according to claim 1, characterized in that, alternatively, the thickness of the wall (10) is increased in order to increase its fire resistance.

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