The cable fire protection material is a new material introduced by European and American countries in the late 1980s for the fireproofing of cable-intensive areas. Mainly include: organic fire blocking materials, inorganic fire blocking materials, fire protection packages, fire barriers, cable fire protection coatings, etc., applicable to the construction of the cable to prevent the expansion of the fire accident caused by the ignition of the cable, is to plug the cable dense area. Take protective measures.
1 Causes of cable fires The accidents caused by the delay of fire due to the fire of cables have spread throughout power plants, substations, factories, high-rise buildings, post offices, railways, and ships. There are two main reasons for the occurrence of cable fires.
1.1 In the case of the cable itself, under excessive load and short-circuit current for a long time, the aging of the cable insulation fires, and the poor contact of the cable connector causes local heating to cause ignition.
1.2 Situations that are external factors such as leakage of oil-bearing equipment, fire and cables, accidental fire in engineering operations, fire prevention measures in cable trenches, etc.
According to relevant statistical data, due to the fire caused by the cable itself, the total number of cable fire accidents does not account for the major proportion, and the external causes of the cables are various and they are difficult to prevent.
2 Characteristics and hazards of cable burning As we all know, the burning of objects must have three elements: combustibles, ignition points and air.
The insulating materials and protective layers of all types of cables that have been widely used up to now have mostly used flammable organic substances. Cables with oil, paper, and asphalt as cable materials have been eliminated, but many old factories and so on continue to be used. Polyethylene, cross-linked polyethylene, polypropylene, polystyrene, natural rubber and other materials are used in a large number of cables. These materials have an oxygen index of 19 or less, and they generally ignite when they are 300 to 400. Moreover, the amount of heat generated when burning is greater than that of coal of the same quality. Therefore, once the cables made of these materials are fired, they will not self-extinguish and burn, which is the main cause of the spread of cable fires.
When a cable emits a large amount of toxic gas in the flue gas when it burns and reaches a certain concentration, it will damage human health and cause death.
The cable quickly self-extinguished after it caught fire. There were also examples of accidents that did not cause accidents. However, this was mainly due to factors such as cable type, number, number of layers, and environmental conditions.
The old standard tests for single PVC cables showed no flammability, but in the large-scale installation of multiple cable groups, once the cables caught fire, the cables were heated by each other to cause a wide range of high temperatures. The formation of ductile flame does not self-extinguish. Under the condition of supplying the same amount of air, the horizontal laying is smaller than the vertical burning speed and the flame propagation speed.
3 commonly used cable fire protection materials 3.1 organic fire blocking material organic fire blocking material is made of organic synthetic resin as a binder, together with fireproofing agent, filler and other materials from rolling. Has good plasticity, excellent fire performance, long fire-resistant time, low smoke, can effectively prevent the fire from spreading and the spread of smoke. It is especially suitable for the fire blocking of the gaps between the bundled cable or cable dense area and the cable, cable and other objects.
3.2 Inorganic fireproof blocking materials Inorganic fireproof blocking materials are made of high temperature resistant inorganic materials and fireproofing agents. They have high fire resistance and mechanical strength. They can effectively prevent the flame from penetrating and prolonging combustion. It is a kind of quick solid type. Non-combustible material. It is used in combination with organic sealing materials to build fire walls and fire blocking sections.
3.3 Fireproof pillows Fireproof pillows are made of non-combustible fabrics that constrain the refractory material to a variety of shapes. In case of fire, the material can rapidly expand, form a tight sealing layer, and play a role in heat insulation and fire resistance. It is suitable for the sealing of large holes, making it easy to replace or redo.
3.4 Fireproof partitions, fireproof tanks fireproof partitions and fireproof tank boxes are characterized by non-combustibility, corrosion resistance, oil resistance, light weight, high strength, and easy installation. Used in conjunction with blanking material, it can prevent the cable from catching fire and the fire separation of important cable loops.
3.5 cable anti-winter coating cable fire retardant coating applied to the surface of the cable, in the event of fire expansion to produce a uniform and dense honeycomb insulation layer, a good thermal insulation and fireproof effect, and with water, oil, Salt and other characteristics. Suitable for various types of cable fire protection, can effectively prevent the spread of flame along the cable to meet the power engineering cable design specifications.
4 Selection of cable fire protection materials 4.1 Fire resistant slot box Applicable places and functions: Fire protection, fire separation and prevention of cable ignition delay when cables of various voltage levels are laid on brackets or bridges. The construction acceptance criteria are as follows: 1 The appearance quality of the inspection box shall be checked before installation, and the product qualification certificate shall be checked; the installation of the 2 tank box shall be generally smooth, reliable and sealed. The end of the box and every 1000mm are tied tightly with strapping and locking buckles; the length between the bottom of the 3 box and the support (support) is fixed with a bolt of suitable length, the direction of the bolts is the same, and a special gasket is used. If the support arm or bracket is not neat, it should be corrected during installation; 4 The insulation pad installed in the slot box should be arranged neatly and evenly, and meet the design requirements. The damaged insulation pad should not be installed in the slot box. ;5In the trough box installed in the lower part of the outdoor or oil-containing equipment, the opening of the clamp should be downwards, and the end should be installed in rainproof mode; 6 When the end of the trough box and the cable hole are sealed with the fireproof package and the organic fireproof blocking material, Should be sealed tightly.
4.2 Fire barriers are suitable for places and functions: A-type panels are suitable for large-scale cable holes and cable vertical shafts that need to be carried. B-type plate is suitable for general cable hole plugging. It can be used to build fire walls for cable tunnels and make fire barriers. C-shaped plate is suitable for making cable layer spacers, making various shapes of fireproof cover and fireproof baffle.
Construction acceptance standards: 1 Before installation, the appearance quality of the clapboard shall be inspected and the product qualification certificate shall be inspected; 2 Two special hook bolts shall be installed on each bracket bracket arm to make the baffle plate and the cable support bracket firmly fixed; The partitions are vertical or parallel to the brackets, and the whole should be at the same level. The bolt head should not be exposed too long. Special gaskets are used. In case of bridge or bracket is not flat, the installation should be corrected; 3 connection between the partition should be about 50mm overlap, with bolts, using a special gasket.
Installed in the process of gaps and gaps with a large area of ​​organic fire blocking plug material tight; 4 using partitions to seal the hole should be fixed firmly, the fixing method should meet the design requirements.
4.3 organic fire blocking materials applicable places and functions: 1 with fire, smoke, dust, small animals and other functions. 2 It is applicable to the fire resistance around the cable, through hole of the cable, cable pipe nozzle and other small pores. 3 In combination with inorganic fireproof blocking materials, fire blocking packages and fireproof partitions, they can be used in combination as required. 4 applies to all kinds of indoor and outdoor environmental conditions.
Construction Acceptance Criteria: 1 The organic fireproof plugging material shall be densely embedded in the pores to be plugged during construction; 2when the organic fireproof plugging material is wrapped around the cable according to the design requirements, the package shall be evenly packed; 3 When the fire blocking material is used for blocking, the organic fire blocking material should be slightly higher than the partition plate, and the high part should be shaped. 4 In the cable at both sides of the fire blocking wall, the organic fire blocking material and the inorganic fire blocking material should be sealed; The two ports of the reserved hole and cable protection pipe should be sealed with organic plugging materials. The depth of the plugging material embedded nozzle should not be less than 50mm. The reserved plugging should be smooth.
4.4 Inorganic fire blocking materials Applicable places and functions: 1 It is applicable to the plugging of cable penetration holes and vertical shafts.
2 It can be used in combination with organic fire blocking materials to build fire walls and fire blocking sections. 3 Applicable to all kinds of indoor conditions without water.
Construction acceptance standards: 1 Before the construction of the cable, according to the size of the hole to be sealed, strictly follow the requirements of the product description. When the hole area is larger than. 2m2, and possible pedestrians should take reinforcement measures; 2 when using inorganic fire blocking materials to build a fire wall, according to the design thickness of the fire wall, using prefabricated or cast-in-place, from the bottom of the pet or cast; prefabricated resistance The surface of the fire wall is painted with inorganic fire blocking materials; 3 The fire resistance wall should be installed at the cable support frame, and the cable should be set up with a reserved hole for cable and a drainage hole at the bottom.
4.5 The location and function of the fire-retardant package: The combination of fire-retardant package and organic fire-blocking material and fire-proof baffle can be used in the following places; 1 The cable is passed through the holes of the floor and the holes in the wall are blocked; 2 The fire wall and the fire-stopping section are constructed. ;3 Shaft and trough box end plugging.
Construction Acceptance Criteria: 1 Before installation, make the necessary finishing of the cables, check whether the fire packets are damaged or damaged, and do not use broken fireproof packets; 2 Wrap a layer of organic fireproof blocking material around the cables to prevent the fire from forming evenly. In people's cable gaps, the fire-resistance packages should be cross-piled. 3 When the fire-retardant wall is constructed with a fire-resisting package, the bottom of the fire-resisting wall is constructed with bricks, and a drainage hole is provided. Fixed measures should be taken to prevent the fire wall from collapsing.
4.6 Self-adhesive fireproof tapes Suitable places and functions: 1 Wrap around cables on one or both sides of the cable through-hole blocking layer, on the cables on both sides of the flame-retardant wall or on other fireproof cables required for field protection. (2) Set up fire-resistant sections, fire protection for cables on both sides of the intermediate joint and its adjacent cables and terminal cables.
Construction Acceptance Criteria: 1 Cable sorting before construction; 2 Construction according to product specification requirements; 3 Multiple small-section control cables bundled and wound with self-adhesive fireproof tapes, and the gaps at both ends shall be tightly sealed with organic fireproof plugging materials.
4.7 Fire Resistant Coatings Applicable places and functions: 1 Cables applied on one or both sides of the through-hole sealing layer, fire-protected cables on the sides of the flame-retardant wall or other fields. 2 Apply and remove the cable from and to the end of the slot box. 3 Suitable for indoor dry and clean environment conditions.
Construction acceptance standards: 1 TJT removes dust and oil on the cable surface. Before painting, stir the paint. If the coating is too thick, it should be diluted according to the type of coating. Dilution should be done according to the type of coating. When the cable is laid horizontally, it should be brushed evenly along the direction of the cable, and the cable should be laid vertically. The coating should be painted from top to bottom. Thickness should meet the requirements of the product, and the interval between paintings should not be less than the specified time. 3 When the cable is densely packed or bundled, it should be painted one by one and must not be missed.
4.8 Location and function of cable middle splice box: It is applicable to the protective isolation of indoor and outdoor cable middle connectors.
Construction Acceptance Criteria: 1 The cable connector protection box must be constructed in the power outage state. The upper and lower parts of the joint box should be firmly connected with bolts, and the two ends should be sealed with organic fire blocking material; 2 The cables and joints at both ends of the cable protection box The cables in adjacent sections should be fireproofed.
5 Development prospects of cable fireproof materials The development of cable fireproof materials is bound to tend to be non-combusting, smoke-free, light-weight, highly efficient, heat-insulating and sound-absorbing; fire-resistance is reliable, fire-resistance limit can be up to several hours; materials are cheap, construction costs are low Weather resistance is good, there is no cracking and shedding; construction on the profiled surface has advantages. Not only can be used for fire protection of cables, but also in the field of building insulation, petrochemical and metallurgical buildings in the field of insulation and energy conservation can also be applied.
As a new type of product, the fireproof material has a long-term market prospect, though not long. Widely used in the cable-intensive areas of electric power, petrochemical, metallurgy, aviation, post and telecommunications, coal mines and other related companies, will surely play an increasingly important role in preventing the spread of cables, reducing the losses caused by fires and ensuring the smooth progress of production. The role.
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