The concepts of flame-retardant cables and fire-resistant cables in Hebei Cable Factory are different, and correct understanding can help correct design and selection. It is easy for people to confuse the concepts of flame-retardant cables and fire-resistant cables. Although flame-retardant cables have many advantages that are more suitable for chemical companies, such as low halogen, low smoke flame retardant, etc., in general, fire-resistant cables can replace flame-retardant cables , And flame-retardant cables cannot replace fire-resistant cables.
The burning of the cable in the wire and cable is due to the external heating to generate flammable gas. To achieve the purpose of flame retardancy, the three elements that cause combustion must be suppressed, namely: combustible gas, heat and oxygen. In the past, the use of halogen-containing halides and metal oxides to achieve flame retardant purposes, with the continuous improvement of technological level, the flame retardant problem has been flame retarded from the past halogen, and further developed into low halogen, halogen free flame retardant .
Flame retardant cable refers to a cable that is burned under the specified test conditions. After the test source is removed, the flame spread is only within the limited range, and the residual flame or residual flame can extinguish itself within a limited time. Its basic characteristic is: It may be burnt out and cannot run in the case of fire, but it can prevent the spread of fire. In layman's terms, in the event of a cable fire, it is possible to limit the combustion to a local range without spreading, to protect other various equipment, and to avoid greater losses. A
Structural characteristics of flame-retardant cable: The structure of flame-retardant cable is basically the same as ordinary cable, the difference is that its insulation layer, sheath, outer sheath and auxiliary materials (including tape and filling) are all or partly made of flame-retardant material. A
Refractory cable refers to the performance that the sample is burned in the flame under the specified test conditions and can still maintain normal operation for a certain period of time. Its basic characteristic is: the cable can still maintain the normal operation of the line for a period of time under burning conditions. In layman's terms, in case of fire, the cable will not burn at once, and the circuit is safer.
Structural characteristics of fire-resistant cables: The structure of fire-resistant cables is basically the same as ordinary cables, the difference is that the conductors of fire-resistant cables use copper conductors with good fire resistance (the melting point of copper is 1083 ° C), and a fire-resistant layer is added between the conductor and the insulation layer . The refractory layer is formed by wrapping multiple layers of mica tape. Because the allowable working temperature of different mica tapes varies greatly, the key to the fire resistance of the cable is the mica tape. A
The main differences of are:
1. Difference in principle: The principles of fire-resistant cables and flame-retardant cables are different. The flame retardant principle of halogen-containing cables relies on the flame retardant effect of halogen, and the flame retardant principle of halogen-free cables relies on the precipitation of water to reduce the temperature to extinguish the fire. Fire-resistant cable relies on the fire-resistant and heat-resistant characteristics of mica material in the fire-resistant layer to ensure that the cable works normally even in the event of a fire.
2. The difference between structure and material: The structure and material of fire-resistant cable are also different from the flame-retardant cable. A
The basic structure of the flame-retardant cable is: (1) the flame-retardant material is used for the insulation layer (2) the flame-retardant material is used for the sheath and the outer sheath; (3) the flame-retardant material is used for the wrapping and filling. Fire-resistant cables usually add a refractory layer between the conductor and the insulating layer, so in theory, a refractory layer can be added to the structure of the flame-retardant cable to form a cable that is both flame-retardant and fire-resistant, but the actual This is not necessary. Because of the refractory layer of the refractory cable, usually multiple layers of mica tape are directly wrapped around the conductor. It can withstand burning for a long time, even if the polymer applied to the flame is burned, it can ensure the normal operation of the line. 3. The advantages and disadvantages of flame retardant and fire resistant: flame retardant cables, halogen-free cables and fire-resistant cables have clear concepts.
It can be seen from the characteristics of the above flame-retardant cables and fire-resistant cables that fire-resistant cables play an important role in modern cities and industrial buildings. Because in the event of a fire, the power supply loops of the control, monitoring, guidance, and alarm systems must maintain normal operation. Therefore, the cable is mainly used in emergency power supply to the user's fire equipment, fire alarm equipment, ventilation and smoke extraction equipment, guide lights, emergency power sockets, emergency elevators and other power supply circuits.