Security and fire alarm prevention cable capable of being used in extremely cold region

Abstract

The utility model discloses a safe fireproof alarm cable used in extremely cold areas. The core wire insulating layers are sequentially wrapped outside the inner conductors, and then the core wire insulating layers and the inner conductors are twisted together and then are sequentially wrapped by the sheath layers; the core wire insulating layer and the sheath layer are both made of double-layer materials of an inner polyvinyl chloride material and an outer polyethylene material in a co-extrusion mode, and an interlocking structure is arranged between the inner polyvinyl chloride material and the outer polyethylene material. The safe fire alarm prevention cable can be used in an extremely low temperature environment, has excellent high flame retardation performance and good low temperature resistance performance, and is economical and environment-friendly.

Description

Technical Field

[0001] The utility model relates to a safety cable, in particular to a security fire alarm cable which can be used in extremely cold areas. Background Art

[0002] Security fire alarm cables are an important part of fire warning systems for buildings and facilities. They are usually arranged inside buildings or between buildings and fire control centers to detect fires in a timely manner and send alarm signals to facilitate evacuation and fire fighting. In order to improve the safety and reliability of fire alarm cables in the event of a fire, the insulation and sheath materials of fire alarm cables must not be easily burned. If combustion is unavoidable, the speed and scope of spread must be minimized. In addition, the formation and density of smoke after combustion and the toxicity of smoke gases must be controlled to protect personnel from harmful gases.

[0003] According to the NEC (National Electrical Code) requirements for the installation location and environment of security fire alarm cables, the highest combustion level requirement for security fire alarm cables is plenum rated cables, which are used in empty spaces on building walls or ceilings or HVAC ducts. These spaces are usually used for heating, ventilation and central air conditioning. In buildings with HVAC systems, air ducts supply air from external HVAC units to the interior of the building, and then return air through the open space above the ceiling, making it a fast air circulation space. Once a fire occurs, thick toxic smoke will quickly spread throughout the building, and the fire will quickly spread along the cables to the entire building, so plenum rated cables with higher flame retardant and low smoke levels are needed.

[0004] Plenum Rated Cable needs to pass the US NFPA 262 (Flame propagation and smoke test for wires and cables for air handling spaces) or the Canadian CSA C22.2 No.0.3-09FT6 (Horizontal flame and smoke test). This test evaluates the flame spread distance, smoke density and toxic gas release concentration of cables under fire conditions. On this strict basis, CSA C22.2 No.208 (Canadian Fire Alarm and Signal Cable) further adds a -30℃ cold bending requirement for the insulation and sheath of the cable to adapt to the extremely low and cold climate conditions in northern Canada. In such an extreme low temperature environment, the cold and dry climate conditions will make the plastic material brittle and hard, and the bending performance, flexibility and impact resistance of the cable will be greatly reduced.

[0005] For the polyvinyl chloride materials commonly used in such highly flame-retardant security fire alarm cables, in order to ensure that they pass the harsh combustion test conditions, a large amount of inorganic fillers and flame retardants need to be added to the materials. These fillers and additives will make the materials more rigid, reduce the bending performance under low temperature conditions, increase the risk of rupture or cracking of the materials at low temperatures, reduce the reliability and durability of the products, and thus cause delays or failures in fire signals, exacerbating the danger of fire. Therefore, security fire alarm cables used in high-latitude inland cold areas far from the ocean, such as inland Siberia, northern Alaska, and northern and inland Canada, will give priority to expensive fluoroplastics as insulation and sheath materials. On the basis of taking into account high flame retardancy and low temperature resistance, the cable cost and design redundancy are greatly increased. At the same time, fluoroplastics will release harmful gases and wastewater during the production and processing process, which will have a certain impact on the environment. Fluorine compounds are difficult to degrade in the natural environment, which will also pose potential risks to the ecosystem.

[0006] Therefore, the prior art lacks and urgently needs an economical and environmentally friendly fire alarm cable that has high flame retardant properties and good low temperature resistance in an extreme low temperature environment. Utility Model Content

[0007] In order to solve the problems existing in the background technology, the utility model proposes an economical and environmentally friendly fire alarm cable that has high flame retardancy and good low temperature resistance in an extremely low temperature environment. The utility model can be used in extremely cold areas and also obtains advantages in cost and environmental protection to replace existing products.

[0008] The technical solution adopted by the utility model is:

[0009] The utility model comprises a core wire insulation layer and a sheath layer wrapped outside the inner conductor, the inner conductor is wrapped with a core wire insulation layer of polyvinyl chloride material and polyethylene material from the inside to the outside, and a plurality of inner conductors wrapped with the core wire insulation layer are twisted together and then wrapped with a sheath layer of polyvinyl chloride material and polyethylene material from the inside to the outside;

[0010] The core wire insulation layer and the sheath layer are both made of co-extruded double-layer materials. The inner layer material is a polyvinyl chloride material that can bear the flame retardant properties of the cable, and the outer layer material is a polyethylene material that can bear low-temperature bending resistance and waterproof properties. The contact surface between the inner layer material and the outer layer material is set to a jagged structure similar to a sawtooth.

[0011] A layer of highly flame-retardant and low-smoke aluminum-plastic composite tape is also provided on the inner surface of the sheath layer.

[0012] The multiple inner conductors wrapped with core wire insulation layers and a grounding wire conductor are twisted together and then wrapped with a sheath layer.

[0013] The beneficial effects of the utility model are:

[0014] The utility model combines polyvinyl chloride material with polyethylene material, which not only meets the strict flame retardant, low smoke and low toxicity standards of ventilation cables, but also exhibits excellent low-temperature bending resistance in extreme low temperature environments, providing a safer and more reliable solution for security fire alarm cables for buildings in extremely cold areas.

[0015] The utility model can replace fluoroplastic cables, which not only greatly reduces costs, but also avoids the potential risks of fluorine compounds to the environment. This innovation not only solves technical problems, but also succeeds in industrial practice, providing a new choice for environmentally friendly, safe and reliable cable applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The utility model is a structural schematic diagram of a security fire alarm cable.

[0017] In the figure, there are an inner conductor (1), a polyvinyl chloride material (2), a polyethylene material (3), a grounding conductor (4), and a highly flame-retardant and low-smoke aluminum-plastic composite tape (5). DETAILED DESCRIPTION

[0018] The utility model is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0019] like Figure 1 As shown, the cable includes a core wire insulation layer and a sheath layer wrapped outside the inner conductor 1, the inner conductor 1 is wrapped with the core wire insulation layer in turn, and multiple inner conductors 1 wrapped with the core wire insulation layer are twisted together and then wrapped with the sheath layer in turn outside; the core wire insulation layer and the sheath layer are both made of double-layer materials, and the contact surface between the inner layer material and the outer layer material is set to a jigsaw structure.

[0020] In the double-layer material of the core wire insulation layer and the sheath layer, the inner layer material is a polyvinyl chloride material 2, and the outer layer material is a polyethylene material 3. The double-layer material of the core wire insulation layer and the sheath layer can generally be prepared by co-extrusion.

[0021] The outer surface of the polyvinyl chloride material 2 of the inner layer material is provided with a strip groove structure, and the inner surface of the polyethylene material 3 is also provided with a strip groove structure. The strip groove structures of the polyvinyl chloride material 2 and the polyethylene material 3 are interlocked to form a jagged shape.

[0022] Polyvinyl chloride material and polyethylene material are used as the inner layer and covering layer of the core wire and sheath respectively.

[0023] In a specific implementation, a layer of high flame retardant and low smoke aluminum-plastic composite tape 5 is further provided on the inner surface of the sheath layer. The high flame retardant and low smoke aluminum-plastic composite tape comprises aluminum foil Mylar and plastic film, wherein the plastic film can be made of polyimide material.

[0024] In a specific implementation, a plurality of inner conductors 1 wrapped with a core wire insulation layer and a ground wire conductor 4 are twisted together, and then wrapped with a sheath layer on the outside.

[0025] In specific implementation, it can be prepared according to the following embodiments:

[0026] S1, core wire inner layer high flame retardant low smoke polyvinyl chloride extrusion:

[0027] Highly flame-retardant and low-smoke polyvinyl chloride insulation material is used as the inner layer of the core wire, and is tightly extruded on a single or multiple inner conductors 1 through a specially designed serrated outer mold, so that a core wire with evenly distributed strip grooves is formed on the surface of the polyvinyl chloride material 2, and each strip groove is evenly spaced along the circumferential direction, and each strip groove is arranged along the axial direction.

[0028] In the specific implementation, the serrated outer mold adopts a tungsten steel mold, the serration protrusion height is 0.1mm, the serration protrusion width is 0.2mm, the serration spacing is 0.5mm, and it is evenly distributed according to the required core wire outer diameter.

[0029] S2, core wire coating modified linear low density polyethylene extrusion:

[0030] Polyethylene material 3 is used as the core wire coating layer, and the coating layer extrusion main machine and the inner layer extrusion main machine are arranged in parallel. The polyvinyl chloride material 2 and the polyethylene material 3 are melt-coextruded to form a staggered shape to form a staggered layer, thereby ensuring that the polyvinyl chloride material 2 of the inner layer of the core wire and the polyethylene material 3 of the outer layer of the core wire are integrated, thereby enhancing the adhesion of the two layers of materials. The thickness of the core wire coating layer excluding the staggered layer (the staggered layer refers to the area where polyvinyl chloride and polyethylene are fused to each other through the grooved surface, the above base color part) is about 0.15mm, forming the final core wire.

[0031] S3, core wire overall cabling:

[0032] The specific number of cores is selected according to the specific signal, power supply and monitoring requirements of the fire alarm cable, and multiple core wires are evenly dispersed and twisted together. After twisting, a high flame retardant and low smoke aluminum-plastic composite tape 5 with aluminum foil Mylar can be used for overall covering according to application requirements.

[0033] In this embodiment, the highly flame-retardant and low-smoke aluminum-plastic composite tape 5 comprises aluminum foil Mylar and a plastic film, and the plastic film is made of polyimide material.

[0034] S4, sheath inner layer high flame retardant low smoke polyvinyl chloride extrusion:

[0035] Highly flame-retardant and low-smoke polyvinyl chloride insulation material is also used as the inner layer of the sheath, and is tightly extruded on the outer surface of the highly flame-retardant and low-smoke aluminum-plastic composite belt 5 through a specially designed serrated outer mold, so that a uniformly distributed strip groove-shaped sheath is formed on the outer surface, and each strip groove is evenly spaced along the circumferential direction, and each strip groove is arranged along the axial direction.

[0036] In specific implementation, the serrated outer mold adopts a tungsten steel mold, the serration height is 0.1mm, the serration width is 0.2mm, the serration spacing is 0.5mm, and it is evenly distributed according to the required cable outer diameter.

[0037] S5, sheath coating modified linear low density polyethylene extrusion:

[0038] Polyethylene material 3 is also used as the sheath coating layer. The coating layer extrusion main machine and the inner layer extrusion main machine are arranged in parallel. The polyvinyl chloride material 2 and the polyethylene material 3 are melt-coextruded to form a staggered shape to form a staggered layer, thereby ensuring that the polyvinyl chloride material 2 of the inner layer of the sheath and the polyethylene material 3 of the outer layer of the sheath are integrated, thereby enhancing the adhesion of the two layers of materials. The thickness of the sheath coating layer excluding the staggered layer is about 0.15mm, forming the final sheath.

[0039] The specific test conditions of the embodiments of the present utility model are as follows:

[0040] This embodiment performs a combustion test according to the standard NFPA 262, "Standard for Flame Propagation and Smoke Test Methods for Wires and Cables in Air Handling Spaces" issued by the National Fire Protection Association (NFPA) of the United States.

[0041] The measured flame propagation distance is 0.52-0.67m, which is lower than the maximum flame propagation distance of 1.52m required by the standard. The peak optical density of smoke released during combustion is 0.08-0.17, which is lower than the maximum optical density requirement of 0.5 required by the standard. The average optical density is 0.11-0.13, which is lower than the maximum optical density requirement of 0.15 required by the standard. The above tests show that the security fire alarm cable of this solution has sufficient fire resistance and low smoke generation characteristics.

[0042] This embodiment performs low-temperature cold bending and winding rod tests on the cable core wire and sheath finished products according to CSA C22.2 No.208, i.e. "Canadian Fire Alarm and Signal Cables". The test low-temperature gear intervals are -30°C, -40°C, -50°C, and -60°C, respectively. There are 10 test samples in each gear interval. The measured results show that the cable core wire and sheath finished products are intact and have no cracks or fragments after the low-temperature cold bending and winding rod tests at 30°C, -40°C, and -50°C. After the test samples in the curled winding state are placed in a -60°C low-temperature cooling box for 4 hours and taken out, the polyethylene coating layer is intact and has no cracks, but through the outer transparent polyethylene layer, it can be observed that the inner layer of polyvinyl chloride material has undergone a silk screen-like fragmentation. After the outer transparent polyethylene layer is separated, the inner layer of polyvinyl chloride material is dispersed and fragmented. The above tests show that the finished products of the security fire alarm cable core wire and sheath of this scheme can pass the -50°C low-temperature cold bending and winding rod test at the lowest.

[0043] The security fire alarm cable of this embodiment combines the above key tests and the full-function test performed in accordance with UL 1424 and CSA C22.2No.208, and can meet the installation, implementation and application of 75°C temperature ventilation cable grade security fire alarm cables in high-latitude inland extremely cold areas.

[0044] The above specific implementation modes are used to explain the present invention rather than to limit the present invention. Any modification and change made to the present invention within the spirit of the present invention and the protection scope of the claims shall fall within the protection scope of the present invention.

[0045] The above description is only a preferred embodiment of the present utility model, so all equivalent changes or modifications made according to the structure, features and principles described in the scope of the present utility model patent application are included in the scope of the present utility model patent application.

Claims

1. A security fire alarm cable that can be used in extremely cold areas, characterized by: It comprises a core wire insulation layer and a sheath layer wrapped outside the inner conductor (1), the inner conductor (1) is sequentially wrapped with the core wire insulation layer, and a plurality of inner conductors (1) wrapped with the core wire insulation layer are twisted together and then sequentially wrapped with the sheath layer outside; the core wire insulation layer and the sheath layer are both made of double-layer material, and the contact surface between the inner layer material and the outer layer material is arranged in a jigsaw-like structure.

2. The security fire alarm cable that can be used in extremely cold areas according to claim 1 is characterized by: The inner surface of the sheath layer is also provided with a layer of highly flame-retardant and low-smoke aluminum-plastic composite tape (5).

3. The security fire alarm cable that can be used in extremely cold areas according to claim 1 is characterized by: The plurality of inner conductors (1) wrapped with a core wire insulation layer and the ground wire conductor (4) are twisted together and then wrapped with a sheath layer on the outside.

4. The security fire alarm cable that can be used in extremely cold areas according to claim 1 is characterized by: In the double-layer material of the core wire insulation layer and the sheath layer, the inner layer material is a polyvinyl chloride material (2), and the outer layer material is a polyethylene material (3).

5. The security fire alarm cable that can be used in extremely cold areas according to claim 1 is characterized by: The outer surface of the polyvinyl chloride material (2) of the inner layer material is provided with a strip groove-like structure, and the inner surface of the polyethylene material (3) is also provided with a strip groove-like structure. The strip groove-like structures of the polyvinyl chloride material (2) and the polyethylene material (3) are interlocked to form a jagged shape.

6. The security fire alarm cable that can be used in extremely cold areas according to claim 2 is characterized by: The highly flame-retardant and low-smoke aluminum-plastic composite tape (5) comprises aluminum foil Mylar and a plastic film, wherein the plastic film is made of polyimide material.

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