A flame-retardant cable box and its installation method

Abstract

This invention discloses a flame-retardant box for cables and its installation method, relating to the field of fire protection equipment. It includes two housings corresponding to cable connectors, each housing having a flame-retardant layer on its inner side. A receiving space is formed between the two housings, comprising a receiving area and a connecting area. The cable connector is located in the receiving area, where a flame-retardant packing material is installed, contacting the cable body and the cable connector. A sealing block is installed in the connecting area to seal the receiving area. A pressure relief plug is installed on one of the housings corresponding to the receiving area. The inner end face of the pressure relief plug in a fully locked state is located inside the housing. When the pressure relief plug is fully locked, the flame-retardant packing material is properly filled when its inner end face contacts it; it is underfilled when its inner end face does not contact it; and it is overfilled when the pressure relief plug is not fully locked. This invention effectively solves the problem of unstable protective effect.

Description

Technical Field

[0001] This invention relates to the field of fire protection equipment, and more particularly to a flame-retardant cable box and its installation method. Background Technology

[0002] Cable joints, as weak points in power transmission systems, are frequently prone to breakdown, explosions, and fires due to factors such as installation techniques, insulation aging, or external environmental factors, seriously threatening the safe operation of power facilities. To address these risks, flame-retardant boxes for encasing cable joints have emerged in existing technologies. These fire-fighting devices typically use a metal shell to provide a physical explosion-proof barrier and are filled internally with flame-retardant materials such as fire-retardant packs and fire-resistant sealant to prevent the spread of flames and blast waves through physical isolation, thereby achieving passive protection for surrounding cables and equipment.

[0003] While existing flame-retardant boxes, as fire-fighting equipment, can prevent the spread of flames, they still have some shortcomings in practical applications. For example, component installation relies on the experience and judgment of workers. Specifically, the filling density and distribution of the flame-retardant material, the insertion depth and pre-tightening degree of the pressure relief plug, and the tightening torque of the housing fastening screws all lack quantitative control methods and depend entirely on the subjective feel and visual experience of the operators. Because the amount of flame-retardant material and the placement of the pressure relief plug are judged based on experience, the state of these two aspects cannot be objectively verified after the flame-retardant box is installed. When the flame-retardant material is filled too densely, it can easily prevent the pressure relief plug from opening normally, causing the housing to crack and fail during an explosion. When the flame-retardant material is insufficiently filled, a flame-retardant blind zone is formed, and high-temperature flames may escape from the gaps and ignite surrounding cables. Therefore, flame-retardant boxes installed based on experience-based judgment result in unstable protective effects as fire-fighting equipment in actual fire scenarios, making it difficult to reliably perform the preset precise protective function.

[0004] Therefore, a flame-retardant box for cables and its installation method are proposed to solve the problem of unstable protective effect. Summary of the Invention

[0005] The purpose of this invention is to provide a flame-retardant box for cables and its installation method, thereby solving the problem of unstable protective effect.

[0006] To achieve this objective, the present invention adopts the following technical solution: A flame-retardant box for cables includes two housings corresponding to cable connectors. Each housing has a flame-retardant layer on its inner side. A receiving space is formed between the two housings. The receiving space includes a receiving area and a connecting area. The cable connector is located in the receiving area. A flame-retardant bag that contacts the cable body and the cable connector is provided in the receiving area. A sealing block is provided in the connecting area. The sealing block is used to close the receiving area. A pressure relief plug in a fully locked state is provided on one of the housings corresponding to the receiving area. The inner end face of the fully locked pressure relief plug is located inside the housing.

[0007] When the pressure relief plug is in a fully locked state, the flame arrestor is properly filled when the inner end face of the pressure relief plug is in contact with the flame arrestor; the flame arrestor is underfilled when the inner end face of the pressure relief plug is not in contact with the flame arrestor; and the flame arrestor is overfilled when the pressure relief plug is not in a fully locked state.

[0008] The flame-retardant layer is any one of epoxy aluminum foil fiberglass cloth layer, high silica aluminum foil cloth layer, and ceramic fiber aluminum foil cloth layer.

[0009] The fire-retardant bag includes a packaging bag and a filler, wherein the packaging bag is any one of a glass fiber cloth bag, a ceramic fiber cloth bag, or a high-silica fiber cloth bag.

[0010] The filler includes an intumescent material, a refractory material, a heat-insulating material, and a fire-extinguishing dry powder. The intumescent material is any one of expandable graphite, aluminum hydroxide, and ammonium polyphosphate. The refractory material is any one of aluminum silicate fiber, high-silica fiber, and ceramic fiber. The heat-insulating material is any one of ceramic fiber cotton, aerogel felt, and expanded vermiculite. The fire-extinguishing dry powder is microencapsulated red phosphorus powder, ammonium polyphosphate powder, or ultrafine ammonium dihydrogen phosphate powder.

[0011] The sealing block includes a sealing ring and sealing mud. The sealing ring is fitted onto the part of the cable body located in the connection area. The sealing mud is placed on both sides of the sealing ring and covers the outside of the corresponding part of the cable body.

[0012] The sealing mud is any one of the following: expanded graphite-based fireproof sealing mud, hydrated salt-based expanded fireproof sealing mud, or organic-inorganic composite fireproof sealing mud.

[0013] One of the housings has a pressure relief hole corresponding to the receiving area. The pressure relief plug is inserted into the pressure relief hole. A protrusion is formed on the outer side of the pressure relief plug along the circumferential direction. A groove is formed on the inner wall of the pressure relief hole corresponding to the protrusion. When the protrusion and the groove are engaged, the pressure relief plug is in a fully locked state.

[0014] An installation method for a flame-retardant cable box, the installation method being applied to the flame-retardant cable box as described above, the installation method comprising the following steps: Step S1: Insert the pressure relief plug into the pressure relief hole on a housing, so that the inner end of the pressure relief plug is inside the housing, making the pressure relief plug semi-locked. Step S2: First, wrap fireproof and arc-resistant tape around the surface of the cable joint, and place the above-mentioned housing below the cable joint so that the cable joint is located within the receiving area; Step S3: Place the sealing block, including the sealing ring and sealing mud, in the connection area, so that the sealing ring is fitted onto the cable body, apply cable sealant at the contact point between the two, and then place the sealing ring at the part of the housing corresponding to the connection area; then fill the sealing mud on both sides of the sealing ring to wrap the cable. Step S4: Fill the receiving area of ​​the above-mentioned housing with a flame arrestor bag, so that the flame arrestor bag contacts the inner end face of the pressure relief plug; then close and lock the other housing with the above-mentioned housing. Step S5: Press the pressure relief plug, which is in a semi-locked state, into the corresponding inner side of the housing so that the protrusion is completely inserted into the groove. The pressure relief plug is in a fully locked state, and the inner end face of the pressure relief plug is in contact with the flame arrestor bag. The flame arrestor bag is properly filled, and the flame retardant box is installed.

[0015] In step S2, when the pressure relief plug moves within the pressure relief hole until the resistance begins to increase, the protrusion is located at the edge of the groove, at which point the pressure relief plug is in a semi-locked state.

[0016] In step S5, when the pressure relief plug in the semi-locked state is pressed into the corresponding inner side of the housing, if the protrusion cannot be pressed into the groove and the pressure relief plug fails to switch from the semi-locked state to the fully locked state, it indicates that the flame arrestor bag is overfilled; if the protrusion can be inserted into the groove, but there is no resistance during the pressing process and the inner end face of the pressure relief plug does not contact the flame arrestor bag, it indicates that the flame arrestor bag is underfilled. When the flame arrestor bag is overfilled, reset the pressure relief plug to the semi-locked state, release the locking of the two shells, take out part of the flame arrestor bag from the receiving area, close the shell and lock it, and press the pressure relief plug into the pressure relief hole again until the protrusion locks with the groove, so that the flame arrestor bag is properly filled. When the flame arrestor bag is not fully filled, reset the pressure relief plug to the semi-locked state, release the locking of the two shells, add some flame arrestor bag into the receiving area, close the shell and lock it, and press the pressure relief plug into the pressure relief hole again until the protrusion locks with the groove, so that the flame arrestor bag is properly filled.

[0017] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a flame-retardant box for cables and its installation method. Addressing the technical problem of unstable protective effects in existing flame-retardant boxes where the amount of flame-retardant material and the placement of pressure-relief plugs rely entirely on worker experience and cannot be objectively verified after installation, this invention clearly divides the containment space into a containment area and a connection area. The cable joint is located within the containment area, and a flame-retardant bag is placed within the containment area to directly contact the cable body and cable joint. Simultaneously, a sealing block for sealing the containment area is placed within the connection area, and a pressure-relief plug is placed on one of the housings corresponding to the containment area, thus linking the filling state of the flame-retardant bag with the state of the pressure-relief plug. In this structure, the flame-arresting bag is placed within the receiving area and directly contacts the cable body and cable joint, its filling boundary is defined by the fixed space of the receiving area. The pressure relief plug is positioned corresponding to the receiving area, creating a spatial relationship between its opening path and the space occupied by the flame-arresting bag. When the flame-arresting bag's filling amount is excessive or insufficient due to worker experience, this spatial relationship directly affects the normal opening of the pressure relief plug. Excessive filling will obstruct the pressure relief channel, while insufficient filling will leave blank areas within the receiving area not covered by the flame-arresting material. By fixing the spatial positional relationship between the flame-arresting bag and the pressure relief plug, the flame-retardant box transforms their interaction from relying on worker experience to a physical relationship determined by the structure itself. This allows the filling state of the flame-arresting bag and the working state of the pressure relief plug to mutually verify and constrain each other after installation, fundamentally eliminating the instability of protective effect caused by improper control of the flame-arresting material filling amount, and significantly improving the protective reliability of the flame-retardant box in actual fire scenarios. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] The structures, proportions, sizes, etc., shown in the accompanying drawings of this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0020] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the internal structure of the shell in this invention; Figure 3 This is a top view of the shell structure in this invention; Figure 4 This is a schematic diagram of the connection structure between the pressure relief plug and the pressure relief hole in this invention; Figure 5 This is a schematic diagram of the internal structure of the fire-retardant bag in this invention; Figure 6 This is a flowchart of the installation method in this invention.

[0021] Illustrations: 1. Shell; 11. Flame-retardant layer; 12. Receiving space; 121. Connection area; 122. Receiving area; 2. Flame-retardant bag; 21. Packaging bag; 22. Filler; 3. Sealing block; 31. Sealing ring; 32. Sealing mud; 4. Pressure relief plug; 41. Protrusion; 42. Pressure relief hole; 43. Groove; 5. Cable connector; 6. Cable body. Detailed Implementation

[0022] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0023] In the description of this invention, it should be understood that the terms "upper," "lower," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. It should be noted that when a component is considered to be "connected" to another component, it can be directly connected to the other component or there may be a component positioned centrally in the connection.

[0024] Example 1: Please see Figure 1-5This embodiment of a flame-retardant cable box includes two housings 1 corresponding to a cable connector 5. Each housing 1 has a flame-retardant layer 11 on its inner side. A receiving space 12 is formed between the two housings 1. The receiving space 12 includes a receiving area 122 and a connecting area 121. The cable connector 5 is located in the receiving area 122. A flame-retardant pack 2 that contacts the cable body 6 and the cable connector 5 is provided in the receiving area 122. A sealing block 3 is provided in the connecting area 121. The sealing block 3 is used to close the receiving area 122. A pressure relief plug 4 in a fully locked state is provided on one of the housings 1 corresponding to the receiving area 122. The inner end face of the fully locked pressure relief plug 4 is located inside the housing 1.

[0025] When the pressure relief plug 4 is in the fully locked state, the flame arrestor 2 is properly filled when the inner end face of the pressure relief plug 4 is in contact with the flame arrestor 2, and is underfilled when the inner end face of the pressure relief plug 4 is not in contact with the flame arrestor 2; when the pressure relief plug 4 is not in the fully locked state, the flame arrestor 2 is overfilled.

[0026] By fitting two housings 1 together to form a receiving space 12, and dividing the receiving space 12 into a receiving area 122 and a connecting area 121, the cable joint 5 is confined within the receiving area 122. Simultaneously, a fire-arresting bag 2, in contact with the cable body 6 and the cable joint 5, is installed within the receiving area 122. A sealing block 3, used to seal the receiving area 122, is installed within the connecting area 121. A pressure relief plug 4 is also installed on one of the housings 1 corresponding to the receiving area 122, thus constructing a protective system with clearly defined structural partitions and coordinated functions. When the cable joint 5 experiences a breakdown, explosion, or combustion due to a fault, the fire-arresting bag 2, located within the receiving area 122 and in direct contact with the cable body 6 and the cable joint 5, rapidly absorbs heat and expands in volume, filling the remaining gaps within the receiving area 122 to form a dense fireproof and heat-insulating layer, effectively preventing the flame from spreading to the surrounding area. At the same time, the sealing block 3 isolates the receiving area 122 from the external environment within the connecting area 121, preventing high-temperature gases and flames from escaping from both ends of the housing 1. As the pressure within the containment zone 122 rises sharply due to an explosion or combustion, the pressure relief plug 4 automatically opens under pressure, allowing the high-pressure gas to be released in a directional manner, preventing the casing 1 from rupturing due to excessive internal pressure. Under the action of this flame-retardant box, the filling state of the flame-retardant pack 2 within the containment zone 122 and the opening function of the pressure relief plug 4 form a spatial relationship. That is, the direct contact between the flame-retardant pack 2 and the cable body 6 and cable connector 5 ensures its immediate response to faulty heat sources. Through the aforementioned structural zoning and functional synergy, the flame-retardant box establishes a clear physical relationship between the filling of the flame-retardant pack 2, the sealing of the sealing block 3, and the pressure relief of the pressure relief plug 4. This transforms the problem of the amount of flame-retardant material filling and the setting of the pressure relief plug 4, which relies on worker experience in traditional installation, into an objective constraint determined by the spatial relationship and assembly sequence of the structure itself. This solves the problem of unstable protective effects caused by installation relying on experience.

[0027] The final installation position of the pressure relief plug 4 and its contact state with the flame arrester 2 become an objective representation of the filling amount of the flame arrester 2. That is, whether the pressure relief plug 4 reaches the fully locked state and whether its inner end face contacts the flame arrester 2 after reaching the fully locked state correspond to the three states of overfilling, proper filling and underfilling of the flame arrester 2, respectively. Thus, the filling state of the flame arrester 2 is directly reflected by the physical state of the pressure relief plug 4, and accurate judgment can be achieved without relying on the experience judgment of the installer.

[0028] Furthermore, the flame retardant layer 11 is any one of epoxy aluminum foil fiberglass cloth layer, high silica aluminum foil cloth layer, and ceramic fiber aluminum foil cloth layer.

[0029] Furthermore, the fire-retardant bag 2 includes a packaging bag 21 and a filler 22, wherein the packaging bag 21 is any one of a glass fiber bag, a ceramic fiber bag, or a high-silica fiber bag.

[0030] Furthermore, the filler 22 includes an intumescent material, a refractory material, a heat-insulating material, and a fire-extinguishing dry powder. The intumescent material is any one of expandable graphite, aluminum hydroxide, or ammonium polyphosphate. The refractory material is any one of aluminum silicate fiber, high-silica fiber, or ceramic fiber. The heat-insulating material is any one of ceramic fiber cotton, aerogel felt, or expanded vermiculite. The fire-extinguishing dry powder is microencapsulated red phosphorus powder, ammonium polyphosphate powder, or ultrafine ammonium dihydrogen phosphate powder.

[0031] Furthermore, the sealing block 3 includes a sealing ring 31 and sealing mud 32. The sealing ring 31 is sleeved on the part of the cable body 6 located in the connection area 121. The sealing mud 32 is disposed on both sides of the sealing ring 31 and covers the outer side of the corresponding part of the cable body 6.

[0032] Furthermore, the sealing mud 32 is any one of the following: intumescent graphite-based fireproof sealing mud, hydrated salt-based intumescent fireproof sealing mud, or organic-inorganic composite fireproof sealing mud.

[0033] In terms of fire resistance, the aforementioned flame-retardant box, after the two shells 1 are joined together, forms an enclosing space 12 that completely encloses the cable connector 5. The shell 1 itself acts as the first physical barrier, preventing external fire sources from directly contacting the cable connector 5. It also confines the flames and high-temperature gases generated when the cable connector 5 malfunctions within the enclosing space 12, preventing them from spreading to the external environment. The flame-retardant layer 11 located inside the shell 1 is tightly attached to the inner wall of the shell 1. Its material itself has non-combustible properties, enabling the shell 1 to maintain structural integrity when exposed to external high temperatures or internal flames. It will not become a new fire source due to its own combustion, thus ensuring the overall fire resistance performance of the shell 1. The sealing block 3 located in the connection area 121 performs the fire-resistant function of sealing the port. The sealing block 3 tightly wraps around the outside of the cable body 6, completely isolating the enclosing area 122 from the external environment. This prevents external flames from entering the enclosing area 122 through the end gaps and also prevents flames generated within the enclosing area 122 from escaping from the end, thus forming a closed fire-resistant unit within the entire enclosing space 12.

[0034] In the flame-retardant layer 11, the fire-arresting bag 2 within the containment area 122 is a core component that effectively suppresses flame spread and extinguishes combustion. The fire-arresting bag 2 is in direct contact with the cable body 6 and the cable joint 5. When the cable joint 5 generates high temperature or open flame due to a fault, the filler 22 in the fire-arresting bag 2 will rapidly absorb heat. The expansion material inside it expands rapidly after being heated, completely filling the gaps between the fire-arresting bags 2 and the gap between the fire-arresting bags 2 and the shell 1, forming a dense heat insulation layer. This process not only blocks the oxygen channel required for flame propagation, but also further isolates heat transfer through the carbonized layer formed by the expansion material at high temperature. At the same time, the refractory material in the fire-arresting bag 2 maintains a solid structure at high temperature, and can continuously withstand the burning of flames without structural collapse. The heat insulation material further delays the conduction of heat to the shell 1, preventing the external temperature of the shell 1 from becoming too high and igniting surrounding equipment. In addition, the fire-extinguishing dry powder filled in the fire-retardant bag 2 will release gas or solid particles with fire-extinguishing activity under high temperature, which can interfere with the chain reaction of the flame and actively inhibit the combustion process, thereby achieving a composite flame-retardant effect from passive isolation to active fire extinguishing.

[0035] In terms of explosion protection, the housing 1 itself is made of high-strength material, capable of withstanding the impact pressure generated when the cable joint 5 explodes without rupturing; this is the foundation of the explosion-proof function. When the cable joint 5 explodes, high-pressure gas is instantly generated in the containment area 122. If the pressure cannot be released in time, the housing 1 may rupture and generate flying fragments, causing secondary damage to surrounding cables and equipment. At this time, the pressure relief plug 4, which is installed on the housing 1 corresponding to the containment area 122, becomes a key safety valve structure. Under normal operating conditions, the pressure relief plug 4 remains sealed, ensuring that the containment area 122 is isolated from the outside and preventing moisture and dust from entering. When the pressure in the containment area 122 caused by the explosion rises to a set threshold, the pressure relief plug 4 will automatically detach or pop out under pressure, forming a directional pressure relief channel on the housing 1, allowing the high-pressure gas to be released in an orderly manner, thereby preventing the housing 1 from rupturing due to excessive internal pressure. The pressure relief method is related to the filling state of the flame arrestor 2. The filling amount of the flame arrestor 2 determines the remaining volume in the containment area 122 that can be used for gas expansion, which in turn affects the rate and peak value of pressure rise. The opening of the pressure relief plug 4 ensures that the pressure always has a safe release outlet regardless of the filling state of the flame arrestor 2.

[0036] In summary, the flame-retardant box provides a basic fire barrier through the flame-retardant layer 11, achieves active flame retardancy and fire extinguishing through the flame-retardant bag 2, ensures end sealing through the sealing block 3, and guarantees safe pressure release through the pressure relief plug 4. The four structural components of the flame-retardant box are arranged in a spatially partitioned manner and coordinated in a functional sequence to form a complete protection system that can cope with the entire process of cable joint 5 failure.

[0037] In one specific embodiment, the shell 1 is made of 304 stainless steel, the flame retardant layer 11 is an epoxy aluminum foil fiberglass cloth layer, the packaging bag 21 is a fiberglass cloth bag, the expanding material is expandable graphite, the fire resistant material is aluminum silicate fiber, the heat insulation material is ceramic fiber cotton, the fire extinguishing dry powder is ultrafine ammonium dihydrogen phosphate powder, and the sealing mud 32 is expandable graphite-based fireproof sealing mud.

[0038] The housing 1 is made of 304 stainless steel, which combines high strength, high toughness, and excellent corrosion resistance. The 1.5mm thick 304 stainless steel housing 1 can absorb impact energy through plastic deformation without brittle fracture in the event of an explosion at the cable joint 5, thus confining the explosion energy within the housing 1. Simultaneously, the dense chromium oxide passivation film formed on its surface can self-repair in humid or corrosive cable trench environments, ensuring that the housing 1 maintains its structural integrity without maintenance for decades of service, providing a durable and reliable physical barrier for all internal protective materials. The epoxy aluminum foil fiberglass cloth used in the flame-retardant layer 11 achieves a composite function of reflective heat insulation and flame-retardant insulation. The aluminum foil layer efficiently reflects the radiant heat generated by the flame back, reducing heat conduction to the housing 1. The fiberglass cloth substrate itself is a non-combustible material, maintaining structural stability at high temperatures. The epoxy coating enhances adhesion to the stainless steel housing 1 and provides additional electrical insulation. This layer forms a thermal buffer interface between the housing 1 and the internal flame-retardant bag 2.

[0039] As the core flame-retardant component directly contacting the cable connector 5 within the containment area 122, the selection of materials for each component reflects a precise match to different protection requirements. The packaging bag 21 is made of fiberglass cloth, which has the advantage of withstanding temperatures up to 550-700℃, not melting or dripping under flame, and possessing good flexibility, allowing it to freely deform according to the spatial shape within the containment area 122, ensuring that the flame-retardant bag 2 can tightly fit the irregular gaps between the cable connector 5 and the shell 1. The expanding material is expandable graphite, characterized by its ability to rapidly expand tens to hundreds of times its original volume when heated to above 150℃. This dramatic expansion can quickly fill the gaps between the flame-retardant bags 2 and the remaining space between the flame-retardant bag 2 and the shell 1 in the early stages of a fire, forming a dense expanded char layer. This not only blocks the oxygen passage but also further isolates heat transfer through the low thermal conductivity of the char layer. The refractory material is made of aluminosilicate fiber, which has the advantage of a long-term service temperature of over 1000℃. Within the carbon layer formed after the expansion of expandable graphite, it forms a stable three-dimensional skeleton structure, preventing the expansion layer from collapsing or peeling off under flame erosion, ensuring that the fire arrestor bag 2 maintains the integrity of the insulation layer under sustained high temperatures. The insulation material is ceramic fiber cotton, which has an extremely low thermal conductivity. It further slows down heat conduction towards the shell 1 through the gaps in the aluminosilicate fiber skeleton, keeping the external temperature of the shell 1 within a safe range. The extinguishing dry powder is ultrafine ammonium dihydrogen phosphate powder, which has the advantages of small particle size and large specific surface area. Upon heating, it can rapidly decompose and release phosphorus-containing active substances with the ability to capture flame free radicals, actively inhibiting the combustion chain reaction at a chemical level. This, combined with the aforementioned physical isolation, forms a dual extinguishing mechanism of chemical and physical methods.

[0040] The sealing putty 32 located in the connection area 121 is made of intumescent graphite-based fireproof putty. Intumescent graphite-based fireproof putty has both plastic sealing properties at room temperature and expansion sealing capabilities at high temperatures. Under normal operating conditions, the putty can tightly fit the gap between the cable body 6 and the end of the shell 1, ensuring the sealing of the receiving area 122. When exposed to high temperatures, the intumescent graphite component in the putty also expands dramatically, completely filling the tiny gap between the cable and the shell 1, forming a self-reinforcing fireproof sealing layer at high temperatures, effectively preventing flames from escaping from the end.

[0041] When cable joint 5 fails, ultrafine ammonium dihydrogen phosphate powder first intervenes in the initial chain reaction of the flame through a chemical extinguishing mechanism. As the temperature continues to rise, expandable graphite and expandable graphite-based fire-retardant sealant begin to expand rapidly almost simultaneously, quickly sealing all gaps and forming a heat-insulating char layer. Aluminosilicate fiber and ceramic fiber cotton maintain the structural stability and low thermal conductivity of the insulation layer during the subsequent sustained high-temperature stage. The epoxy aluminum foil fiberglass cloth flame-retardant layer 11 further reflects and blocks residual heat passing through the fire-retardant bag 2. The 304 stainless steel shell 1 withstands the internal explosion impact while maintaining the overall structure without cracking. With the cooperation of the above-mentioned chemical extinguishing to physical sealing, and from heat insulation barrier to structural protection, each material can play a leading role in different stages after the failure occurs, thus covering the complete process of the cable joint 5 accident from occurrence to end. In terms of functional complementarity, the rapid expansion of expandable graphite fills the gaps that aluminosilicate fiber, as a rigid skeleton, cannot fill on its own. The high-temperature stability of aluminosilicate fiber compensates for the strength reduction of the expanded carbon layer of expandable graphite under long-term high temperature. The low thermal conductivity of ceramic fiber cotton further improves the thermal insulation efficiency of the aluminosilicate fiber skeleton. The chemical fire extinguishing mechanism of ultrafine ammonium dihydrogen phosphate powder supplements the limitation that the aforementioned physical barrier methods cannot actively suppress combustion. The glass fiber bag integrates the above-mentioned multiple functional materials into a unit that is easy to install and position. The expandable graphite-based fireproof sealant forms a two-way seal with the fire-resistant bag 2 in the receiving area 122 at the end. The 304 stainless steel shell 1 provides stable structural support and external protection for all the above materials.

[0042] Example 2: The basic content is the same as in Example 1, except that: Please see Figure 4 In this embodiment, a pressure relief hole 42 is provided on one of the housings 1 corresponding to the receiving area 122. The pressure relief plug 4 is inserted into the pressure relief hole 42. A protrusion 41 is formed on the outer side of the pressure relief plug 4 in the circumferential direction. A groove 43 is provided on the inner wall of the pressure relief hole 42 corresponding to the protrusion 41. When the protrusion 41 and the groove 43 are engaged, the pressure relief plug 4 is in a fully locked state.

[0043] A pressure relief hole 42 is provided on one of the housings 1 for installing the pressure relief plug 4, and a protrusion 41 is formed circumferentially on the pressure relief plug 4 itself. A corresponding groove 43 is provided on the inner wall of the pressure relief hole 42, so that when the pressure relief plug 4 is connected to the housing 1, the protrusion 41 of the pressure relief plug 4 can enter the groove 43, thus forming a separable locking structure. The cooperation between the protrusion 41 and the groove 43 enables the pressure relief plug 4 to achieve stable positioning under normal conditions, ensuring reliable installation of the pressure relief plug 4 on the housing 1, and the groove 43's accommodating effect on the protrusion 41 provides the necessary displacement stroke for the pressure relief plug 4 to detach from the housing 1. When high pressure is generated in the accommodating area 122 due to a fault in the cable connector 5, the internal pressure acts on the pressure relief plug 4, pushing it outward. At this time, the protrusion 41 disengages from the groove 43 under pressure, and the entire pressure relief plug 4 slides outward along the pressure relief hole 42, thereby automatically opening the pressure relief channel without manual intervention. This structure integrates the installation and positioning function of the pressure relief plug 4 with the pressure release function, so that the fixing strength of the pressure relief plug 4 on the housing 1 is precisely limited to a range that can meet the daily sealing requirements and reliably disengage under the set pressure. This solves the technical problem in the background art where the opening pressure is uncontrollable due to the reliance on experience judgment for the installation of the pressure relief plug 4, which in turn affects the stability of the protection effect.

[0044] In the above structure, after the protrusion 41 engages with the groove 43, the final installation position of the pressure relief plug 4 on the housing 1 is defined. The pressure relief plug 4 is only considered to be installed when it is pushed in until the protrusion 41 is fully inserted into the groove 43. At the same time, the state of the protrusion 41 and the groove 43 can also be used to determine whether the flame arrestor bag 2 is placed properly, thereby avoiding the situation where the function of the flame retardant box is affected due to improper placement of the flame arrestor bag 2.

[0045] Example 3: Please see Figure 6 This embodiment describes an installation method for a flame-retardant cable box. The installation method is applied to the flame-retardant cable box of Embodiment 1 or 2, and includes the following steps: Step S1: Insert the pressure relief plug 4 into the pressure relief hole 42 on a housing 1, so that the inner end of the pressure relief plug 4 is located inside the housing 1, and the pressure relief plug 4 is in a semi-locked state. Step S2: First, wrap fireproof and arc-resistant tape around the surface of the cable intermediate joint, and place the above-mentioned housing 1 below the cable intermediate joint so that the cable intermediate joint is located in the receiving area 122. Step S3: Place the sealing block, including the sealing ring and sealing mud, in the connection area, so that the sealing ring is fitted onto the cable body, apply cable sealant at the contact point between the two, and then place the sealing ring at the part of the housing corresponding to the connection area; then fill the sealing mud on both sides of the sealing ring to wrap the cable. Step S4: Fill the receiving area 122 of the above-mentioned housing 1 with a flame arrestor 2, so that the flame arrestor 2 contacts the inner end face of the pressure relief plug 4; then close and lock the other housing 1 with the above-mentioned housing 1. Step S5: Press the pressure relief plug 4, which is in a semi-locked state, into the corresponding housing 1 so that the protrusion 41 is completely inserted into the groove 43, thus completing the locking and completing the installation of the flame retardant box.

[0046] Press the pressure relief plug 4, which is in a semi-locked state, into the corresponding inner side of the housing 1, so that the protrusion 41 is fully engaged in the groove 43, and the pressure relief plug 4 is in a fully locked state. The inner end face of the pressure relief plug 4 is in contact with the flame arrestor bag 2, and the flame arrestor bag 2 is properly filled. The flame retardant box is now installed. In step S2, when the pressure relief plug 4 moves within the pressure relief hole 42 and the resistance begins to increase, the protrusion 41 is located at the edge of the groove 43, at which point the pressure relief plug 4 is in a semi-locked state.

[0047] In step S5, when the pressure relief plug 4 in the semi-locked state is pressed into the corresponding housing 1, if the protrusion 41 cannot be pressed into the groove 43 and the pressure relief plug 4 fails to switch from the semi-locked state to the fully locked state, it indicates that the flame arrestor bag 2 is overfilled; if the protrusion 41 can be inserted into the groove 43, but there is no resistance during the pressing process and the inner end face of the pressure relief plug 4 does not contact the flame arrestor bag 2, it indicates that the flame arrestor bag 2 is underfilled. When the flame arrestor bag 2 is overfilled, reset the pressure relief plug 4 to the semi-locked state, release the locking of the two housings 1, take out part of the flame arrestor bag 2 from the receiving area 122, close the housing 1 and lock it, and press the pressure relief plug 4 into the pressure relief hole 42 again until the protrusion 41 and the groove 43 are locked, so that the flame arrestor bag is properly filled. When the flame arrestor bag 2 is not fully filled, reset the pressure relief plug 4 to the semi-locked state, release the locking of the two housings 1, add some flame arrestor bag 2 into the receiving area 122, close the housing 1 and lock it, and press the pressure relief plug 4 into the pressure relief hole 42 again until the protrusion 41 and the groove 43 are locked, so that the flame arrestor bag is properly filled.

[0048] The above installation method divides the installation process of the pressure relief plug 4 on the housing 1 into two stages: semi-locking and fully locking. The change in mechanical resistance experienced by the pressure relief plug 4 during the transition from the semi-locked to the fully locked state is used as a basis for judging whether the filling amount of the flame arrestor bag 2 in the receiving area 122 is appropriate. In the initial stage of installation, the pressure relief plug 4 is first inserted into the pressure relief hole 42 and pushed to the semi-locked position. At this time, the protrusion 41 on the pressure relief plug 4 is located at the edge of the groove 43 on the inner wall of the pressure relief hole 42, and the inner end of the pressure relief plug 4 is located inside the housing 1, making the pressure relief plug 4 semi-locked and forming a reference for subsequent steps. Subsequently, when filling the receiving area 122 with the flame arrestor bag 2, the flame arrestor bag 2 is placed in contact with the inner end face of the pressure relief plug 4, so that the filling boundary of the flame arrestor bag 2 is physically associated with this reference. When the other housing 1 is closed and locked, the pressure relief plug 4 is pressed further into the corresponding housing 1 from the semi-locked state. This pressing action forces the protrusion 41 of the pressure relief plug 4 to move into the groove 43. During this process, the inner end face of the pressure relief plug 4 is subjected to a reaction force provided by the flame arrestor 2. The magnitude of this reaction force directly depends on the filling density and distribution of the flame arrestor 2 in the receiving area 122. If the flame arrestor 2 is properly filled, a moderate contact is formed between the inner end face of the pressure relief plug 4 and the flame arrestor 2. During the pressing process, the protrusion 41 can overcome the frictional resistance and smoothly enter the groove 43, and the pressing force is within a perceptible normal range. If the flame arrestor 2 is overfilled, the flame arrestor 2 applies excessive reverse pressure to the inner end face of the pressure relief plug 4, making it impossible for the protrusion 41 to cross the edge of the groove 43 and enter the groove 43. The pressure relief plug 4 does not switch to the fully locked state. If the flame arrestor 2 is underfilled, there is a gap between the inner end face of the pressure relief plug 4 and the flame arrestor 2. During the pressing process, the protrusion 41 has no resistance before reaching the groove 43, or only generates minimal resistance when crossing the edge of the groove 43. By observing whether the pressing action can be completed and the presence and magnitude of resistance changes during the pressing process, the installer can objectively determine whether the filling amount of the fire arrestor bag 2 is within the preset appropriate range, thereby achieving on-site inspection and immediate adjustment of the installation quality.

[0049] In the existing flame-retardant box installation process, the filling density of the flame-retardant material and the pressing depth of the pressure relief plug 4 both rely on the operator's subjective feel and visual experience for judgment. After installation, it is impossible to objectively verify the state of these two aspects. As a result, when the flame-retardant bag 2 is filled too densely, it can easily prevent the pressure relief plug 4 from opening normally, thus causing the shell 1 to crack and fail during an explosion. When the flame-retardant bag 2 is not filled sufficiently, a flame-retardant blind zone is formed, allowing high-temperature flames to escape from the gaps. This installation method links the installation process of the pressure relief plug 4 with the filling process of the flame-retardant bag 2. The feasibility of the pressure relief plug 4 changing from a semi-locked state to a fully locked state is directly limited by the actual filling state of the flame-retardant bag 2 in the receiving area 122. Thus, the problem of controlling the filling amount of the flame-retardant bag 2, which originally relied on subjective judgment, is transformed into a problem determined by whether the pressing action of the pressure relief plug 4 can be completed. When the flame arrestor bag 2 is overfilled, the pressure relief plug 4 cannot be pressed into a fully locked state, directly indicating to the installer that it is overfilled. When the flame arrestor bag 2 is underfilled, although the pressure relief plug 4 can be pressed into a locked state, the pressing process lacks normal resistance, and the inner end face of the pressure relief plug 4 does not contact the flame arrestor bag 2, also indicating to the installer that it is underfilled. This installation method further defines the operation process when overfilling or underfilling is detected: resetting the pressure relief plug 4 to a semi-locked state, releasing the lock of the housing 1, removing or adding part of the flame arrestor bag 2, reclosing the housing 1, and re-pressing and locking, thus forming a closed-loop adjustment mechanism in the installation process. Therefore, this installation method eliminates the reliance on worker experience judgment, allowing the filling amount of the flame arrestor bag 2 and the installation state of the pressure relief plug 4 to be verified during installation. This avoids the risk of the pressure relief plug 4 failing to pop open properly due to overfilling or creating a flame-retardant blind zone due to underfilling, solving the problem of unstable protective effect of the flame-retardant box.

[0050] This installation method, based on whether the pressure relief plug 4 can be fully locked during the pressing action, allows installers to accurately determine whether the filling amount of the flame arrestor bag 2 is within the preset range without relying on any measuring tools or subjective experience. This transforms the judgment standard for the filling quality of the flame arrestor bag 2 from individual experience differences to a unified operational result, achieving objective verifiability of the filling amount. When the pressing action detects overfilling or underfilling, this installation method defines a clear operation path for resetting, disassembling, adjusting, and relocking, enabling installers to correct filling deviations on-site in real time, ensuring the consistency of the final installation result and avoiding potential failure risks caused by filling deviations being hidden in the finished product. Through the phased installation of semi-locking and fully locking, the final installation position of the pressure relief plug 4 is defined by the engaging structure of the protrusion 41 and the groove 43, ensuring that the sealing performance of the pressure relief plug 4 under normal conditions and its opening performance under explosive conditions are both within the expected controllable range. This avoids the opening pressure deviation caused by the pressure relief plug 4 being pressed too deeply or too shallowly in traditional installations, achieving effective control of the installation state of the pressure relief plug 4. This installation method integrates quality inspection into the installation process, so that inspection is no longer an independent step after installation, but is completed simultaneously at the moment when the pressure relief plug 4 is finally pressed in and locked. This achieves on-site confirmation of installation quality without adding extra operating steps or testing equipment, and realizes the integration of the installation process and the inspection process.

[0051] During the initial installation phase, the pressure relief plug 4 is pushed in until the resistance begins to increase and the protrusion 41 is positioned at the edge of the groove 43, defined as a semi-locked state. This state establishes a clear benchmark for the subsequent filling and final locking of the flame arrestor bag 2, fixing the position of the inner end face of the pressure relief plug 4 before the flame arrestor bag 2 is filled. This ensures a repeatable reference relationship when the flame arrestor bag 2 contacts the inner end face of the pressure relief plug 4. When filling the flame arrestor bag 2 in the receiving area 122, the contact between the flame arrestor bag 2 and the inner end face of the pressure relief plug 4 is used as the criterion for determining whether the filling is complete. This contact state is an objective physical fact rather than a subjective estimation, uniformly limiting the filling boundary of the flame arrestor bag 2 to the plane defined by the inner end face of the pressure relief plug 4, thereby eliminating fluctuations in the filling amount caused by differences in worker visual inspection. After the housing 1 is closed and locked, the pressure relief plug 4 is pressed from a semi-locked state to a fully locked state. The appropriateness of the flame arrestor bag 2's filling amount is determined by whether the protrusion 41 can enter the groove 43 and whether there is normal resistance during the pressing process. This judgment is based on objective physical phenomena of whether the pressing action is completed and whether there is resistance, and does not rely on the worker's subjective experience or visual inspection. When the pressing action detects overfilling or underfilling, the installation process has a self-correcting capability by resetting the pressure relief plug 4 to a semi-locked state, releasing the housing 1 from locking, removing or adding the flame arrestor bag 2, re-closing and locking, and pressing it again. This ensures that each installation ultimately achieves a convergence result where the flame arrestor bag 2's filling amount and the pressure relief plug 4's locking state simultaneously meet the requirements. This method clarifies the relationship between the flame arrestor bag 2's filling amount and the pressure relief plug 4's installation state, transforming their dependence from individual experience to being constrained by structural linkage.

[0052] It should be noted that this installation method links the process of the pressure relief plug 4's state change with the filling state of the flame arrestor bag 2 within the receiving area 122. This transforms the criterion for determining whether the filling amount of the flame arrestor bag 2 is appropriate from the operator's subjective perception of the resistance to objective physical phenomena such as whether the pressure relief plug 4 can move to the predetermined position, whether it generates perceptible mechanical feedback at the predetermined position, and whether it can maintain a stable state after movement. Through the mating structure between the pressure relief plug 4 and the pressure relief hole 42, the operator only needs to perform the pressing action and observe the final position state of the pressure relief plug 4 and the feedback during the movement to obtain an objective judgment on the filling amount of the flame arrestor bag 2. This embeds the verification of installation quality into the installation steps, achieving objectivity of the judgment criteria and reproducibility of the installation results.

[0053] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A flame-retardant box for cables, characterized in that, The device includes two housings (1) corresponding to the cable connector (5). Each housing (1) has a flame-retardant layer (11) on its inner side. A receiving space (12) is formed between the two housings (1). The receiving space (12) includes a receiving area (122) and a connecting area (121). The cable connector (5) is located in the receiving area (122). A fire-retardant bag (2) is provided in the receiving area (122) and contacts the cable body (6) and the cable connector (5). A sealing block (3) is provided in the connecting area (121) and is used to seal the receiving area (122). A pressure relief plug (4) in a fully locked state is provided on one of the housings (1) corresponding to the receiving area (122). The inner end face of the fully locked pressure relief plug (4) is located inside the housing (1). When the pressure relief plug (4) is in a fully locked state, the flame arrestor (2) is properly filled when the inner end face of the pressure relief plug (4) is in contact with the flame arrestor (2); the flame arrestor (2) is underfilled when the inner end face of the pressure relief plug (4) is not in contact with the flame arrestor (2); and the flame arrestor (2) is overfilled when the pressure relief plug (4) is not in a fully locked state.

2. The flame-retardant box for cables according to claim 1, characterized in that, The flame retardant layer (11) is any one of epoxy aluminum foil fiberglass cloth layer, high silica aluminum foil cloth layer, and ceramic fiber aluminum foil cloth layer.

3. The flame-retardant box for cables according to claim 1, characterized in that, The fire-retardant bag (2) includes a packaging bag (21) and a filler (22), wherein the packaging bag (21) is any one of a glass fiber cloth bag, a ceramic fiber cloth bag, or a high silica fiber cloth bag.

4. The flame-retardant box for cables according to claim 3, characterized in that, The filler (22) includes an intumescent material, a refractory material, a heat insulation material, and a fire extinguishing dry powder. The intumescent material is any one of expandable graphite, aluminum hydroxide, and ammonium polyphosphate. The refractory material is any one of aluminum silicate fiber, high silica fiber, and ceramic fiber. The heat insulation material is any one of ceramic fiber cotton, aerogel felt, and expanded vermiculite. The fire extinguishing dry powder is microcapsule-coated red phosphorus powder, ammonium polyphosphate powder, and ultrafine ammonium dihydrogen phosphate powder.

5. The flame-retardant box for cables according to claim 1, characterized in that, The sealing block (3) includes a sealing ring (31) and sealing mud (32). The sealing ring (31) is fitted onto the part of the cable body (6) located in the connection area (121). The sealing mud (32) is placed on both sides of the sealing ring (31) and covers the outside of the corresponding part of the cable body (6).

6. The flame-retardant box for cables according to claim 5, characterized in that, The sealing mud (32) is any one of the following: expanded graphite-based fireproof sealing mud, hydrated salt-based expanded fireproof sealing mud, and organic-inorganic composite fireproof sealing mud.

7. The flame-retardant box for cables according to claim 1, characterized in that, One of the housings (1) has a pressure relief hole (42) corresponding to the receiving area (122). The pressure relief plug (4) is inserted into the pressure relief hole (42). The outer side of the pressure relief plug (4) has a protrusion (41) along the circumferential direction. The inner wall of the pressure relief hole (42) has a groove (43) corresponding to the protrusion (41). When the protrusion (41) and the groove (43) are engaged, the pressure relief plug (4) is in a fully locked state.

8. A method for installing a flame-retardant box for cables, characterized in that, The installation method is applied to a flame-retardant cable box as described in any one of claims 1-7, and the installation method includes the following steps: Step S1: Insert the pressure relief plug into the pressure relief hole on a housing, so that the inner end of the pressure relief plug is inside the housing, making the pressure relief plug semi-locked. Step S2: First, wrap fireproof and arc-resistant tape around the surface of the cable joint, and place the above-mentioned housing below the cable joint so that the cable joint is located within the receiving area; Step S3: Place the sealing block, including the sealing ring and sealing mud, in the connection area, so that the sealing ring is fitted onto the cable body, apply cable sealant at the contact point between the two, and then place the sealing ring at the part of the housing corresponding to the connection area; then fill the sealing mud on both sides of the sealing ring to wrap the cable. Step S4: Fill the receiving area of ​​the above-mentioned housing with a flame arrestor bag, so that the flame arrestor bag contacts the inner end face of the pressure relief plug; then close and lock the other housing with the above-mentioned housing. Step S5: Press the pressure relief plug, which is in a semi-locked state, into the corresponding inner side of the housing so that the protrusion is completely inserted into the groove. The pressure relief plug is in a fully locked state, and the inner end face of the pressure relief plug is in contact with the flame arrestor bag. The flame arrestor bag is properly filled, and the flame retardant box is installed.

9. The installation method of the flame-retardant box for cables according to claim 8, characterized in that, In step S2, when the pressure relief plug moves within the pressure relief hole until the resistance begins to increase, the protrusion is located at the edge of the groove, at which point the pressure relief plug is in a semi-locked state.

10. The installation method of the flame-retardant box for cables according to claim 8, characterized in that, In step S5, when the pressure relief plug in the semi-locked state is pressed into the corresponding inner side of the housing, if the protrusion cannot be pressed into the groove and the pressure relief plug fails to switch from the semi-locked state to the fully locked state, it indicates that the flame arrestor bag is overfilled; if the protrusion can be inserted into the groove, but there is no resistance during the pressing process and the inner end face of the pressure relief plug does not contact the flame arrestor bag, it indicates that the flame arrestor bag is underfilled. When the flame arrestor bag is overfilled, reset the pressure relief plug to the semi-locked state, release the locking of the two shells, take out part of the flame arrestor bag from the receiving area, close the shell and lock it, and press the pressure relief plug into the pressure relief hole again until the protrusion locks with the groove, so that the flame arrestor bag is properly filled. When the flame arrestor bag is not fully filled, reset the pressure relief plug to the semi-locked state, release the locking of the two shells, add some flame arrestor bag into the receiving area, close the shell and lock it, and press the pressure relief plug into the pressure relief hole again until the protrusion locks with the groove, so that the flame arrestor bag is properly filled.

Images