The selection principle of fire-resistant cables
2019-12-28 15:07:00
A fire-resistant cable is a cable that can operate safely for a certain period of time in the presence of flame. China's national standard GB12666.6 (such as IEC331) will be fire test A, B two levels, A flame temperature 950 ~ 1000 °C, continuous fire time 90min, B-class flame temperature 750 ~ 800 °C, continuous fire time 90min During the entire test period, the test specimen shall withstand the rated voltage of the product.
(1) To select products that have a fire product production license issued by the fire department, the fire-resistant cables of these manufacturers have passed the inspection of the fire department and the inspection of the quality assurance system. The quality of the products is generally stable, and they are not qualified for production. The quality of fire-resistant cables that are produced temporarily by manufacturers is better. In order to ensure the product quality, the manufacturer may also be required to test the fire resistance of the fire-resistant cable to prove that the cable meets the standard requirements.
(2) Reasonably select the type of fire-resistant cable according to the importance of the place of use and the degree of damage after the fire.
(3) Fire-resistant cables are mainly used for fire-fighting equipment, alarm equipment and emergency power supplies. The rated voltage generally does not exceed 1000V, the rated voltage of fire-resistant power cables is 0.6ö1kV, the rated voltage of fire-resistant control cables is 450/750V, and the fire-resistant electric wires for construction are rated The voltage is 450/750V and below. Due to the high temperature on site at the time of fire, taking into account the rise in the conductor resistance, one section of the conductor cross-section should be increased when selecting the cross-section of the conductor.
(4) The mineral insulated cable (MI cable) is composed of a copper conductor, an inorganic mineral insulating layer (magnesium oxide, etc.) and a copper (or stainless steel) sheath. The long-term working temperature is up to 250°C and can withstand 1000°C. 3h fire test, with high temperature, explosion-proof, resistant to mechanical damage and other characteristics. The mineral insulated cable is composed of inorganic materials and does not have aging. It will not emit fumes and toxic and harmful gases when it is surrounded by fire. It can be dangerous in areas with high safety requirements, special fire protection systems and other hazardous locations and various conditions. Used in the area. However, due to its high price, complicated joints and troublesome construction, the use of the cable is also limited.
(5) Fire-resistant cables are fire-resistant only under certain conditions of fire and time. In the event of a severe fire, additional flame-retardant and fire-resistant protection should be considered when laying, such as fire-retardant coatings, fire-retardant tapes, or Placed in a flame retardant tank. In order to prevent the spread of fire on the cable, it is also necessary to implement the necessary flame barrier to prevent the fire from spreading in the event of a serious fire.
(6) The fire-resistant cable is wrapped with multilayer mica tape as a fireproof layer outside the conductor, and its insulation and sheathing does not necessarily have flame retardancy. When a fire occurs, the insulation and sheathing of fire-resistant cable and other polymers will Burning and burning, which in turn has the effect of retarding the fire, has caused unfavorable factors for the safe use of the cable. Therefore, when selecting the cable, the flame retardancy of the cable should be fully considered.
(7) Since the fire-resistant cable is used in a fire state, a halogen-containing fire-resistant cable (such as polyvinyl chloride material) generates a large amount of toxic gas, corrosive gas and smoke when the flame is burned, and escapes and rescues personnel. The rescue work is extremely harmful. Therefore, in important places such as subways, ships, nuclear power stations, oil platforms, banks, large libraries, and indoor public places, low-halogen (halogen-free), low-smoke, and low-toxicity fire-resistant cables should be used to reduce the risk of poisonous fires ( Acid) gas hazards.
(1) To select products that have a fire product production license issued by the fire department, the fire-resistant cables of these manufacturers have passed the inspection of the fire department and the inspection of the quality assurance system. The quality of the products is generally stable, and they are not qualified for production. The quality of fire-resistant cables that are produced temporarily by manufacturers is better. In order to ensure the product quality, the manufacturer may also be required to test the fire resistance of the fire-resistant cable to prove that the cable meets the standard requirements.
(2) Reasonably select the type of fire-resistant cable according to the importance of the place of use and the degree of damage after the fire.
(3) Fire-resistant cables are mainly used for fire-fighting equipment, alarm equipment and emergency power supplies. The rated voltage generally does not exceed 1000V, the rated voltage of fire-resistant power cables is 0.6ö1kV, the rated voltage of fire-resistant control cables is 450/750V, and the fire-resistant electric wires for construction are rated The voltage is 450/750V and below. Due to the high temperature on site at the time of fire, taking into account the rise in the conductor resistance, one section of the conductor cross-section should be increased when selecting the cross-section of the conductor.
(4) The mineral insulated cable (MI cable) is composed of a copper conductor, an inorganic mineral insulating layer (magnesium oxide, etc.) and a copper (or stainless steel) sheath. The long-term working temperature is up to 250°C and can withstand 1000°C. 3h fire test, with high temperature, explosion-proof, resistant to mechanical damage and other characteristics. The mineral insulated cable is composed of inorganic materials and does not have aging. It will not emit fumes and toxic and harmful gases when it is surrounded by fire. It can be dangerous in areas with high safety requirements, special fire protection systems and other hazardous locations and various conditions. Used in the area. However, due to its high price, complicated joints and troublesome construction, the use of the cable is also limited.
(5) Fire-resistant cables are fire-resistant only under certain conditions of fire and time. In the event of a severe fire, additional flame-retardant and fire-resistant protection should be considered when laying, such as fire-retardant coatings, fire-retardant tapes, or Placed in a flame retardant tank. In order to prevent the spread of fire on the cable, it is also necessary to implement the necessary flame barrier to prevent the fire from spreading in the event of a serious fire.
(6) The fire-resistant cable is wrapped with multilayer mica tape as a fireproof layer outside the conductor, and its insulation and sheathing does not necessarily have flame retardancy. When a fire occurs, the insulation and sheathing of fire-resistant cable and other polymers will Burning and burning, which in turn has the effect of retarding the fire, has caused unfavorable factors for the safe use of the cable. Therefore, when selecting the cable, the flame retardancy of the cable should be fully considered.
(7) Since the fire-resistant cable is used in a fire state, a halogen-containing fire-resistant cable (such as polyvinyl chloride material) generates a large amount of toxic gas, corrosive gas and smoke when the flame is burned, and escapes and rescues personnel. The rescue work is extremely harmful. Therefore, in important places such as subways, ships, nuclear power stations, oil platforms, banks, large libraries, and indoor public places, low-halogen (halogen-free), low-smoke, and low-toxicity fire-resistant cables should be used to reduce the risk of poisonous fires ( Acid) gas hazards.
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