Fire-resistant cables refer to cables that can maintain safe operation for a certain period of time under flame burning conditions. Fire-resistant wires are widely used in high-rise buildings, subways, underground shopping malls, power stations, and important industrial and mining enterprises related to fire safety and fire rescue. For example, power supply wires and control wires of fire protection facilities, etc.
1. What is fire-resistant cable?
Fire-resistant cables are divided into Class A and Class B. Class B cables can withstand burning at 750°C to 800°C flame and rated voltage for at least 90 minutes without the cable rupturing. Class A fire-resistant cables developed based on methods such as improving the manufacturing process of the refractory layer and adding refractory layers can withstand burning for at least 90 minutes under a flame of 950°C to 1000°C and a rated voltage without being punctured. The fire resistance of Class A fire-resistant cable is better than Class B. In addition, mineral insulated cable is a fire-resistant cable with better performance made of copper core, copper sheath and magnesium oxide insulation material, referred to as MI (mineral insulated cable) cable. MI cable has good fire protection characteristics and can work at high temperatures of 250°C for a long time. It is also explosion-proof, resistant to strong corrosion, high flow, and radiation resistant. MI cable has the characteristics of explosion-proof, high corrosion resistance, large carrying capacity, radiation resistance, and high mechanical strength. , small size, light weight, long life, smoke-free. However, the price is high. The process is complex and the construction is difficult. In oil irrigation areas, important wooden public buildings, high temperature places and other places where fire resistance is required and it is economically acceptable, fire-resistant cables are used.
2. Fire-resistant cable specifications
Maximum long-term operating temperature of cable
(1) Temperature-resistant vinyl-polyfluoroethylene insulation and sheath: 70℃ and 105℃; Cross-linked polyethylene insulation: 90℃.
(2) Fluoroplastic insulation and sheath: 220℃ and 260℃; Fluoroplastic insulation and 105℃ flame-retardant polyfluoroethylene sheath: 90℃ and 125℃.
(3) Low-halogen, low-smoke flame-retardant polyvinyl chloride insulation and sheathing: 70°C; halogen-free, low-smoke flame-retardant polyolefin insulation and sheathing: 90°C and 125°C.
Minimum ambient temperature.
(1) Flame-retardant polyvinyl chloride insulation and sheath: fixed laying -40℃; non-fixed laying -15℃.
(2) Fluorine plastic insulation and sheath: fixed laying -60℃; non-fixed laying -20℃.
The safe laying temperature of cables should not be lower than 0℃.
Fire resistance properties.
Flame temperature 950℃-1000℃ Flame temperature 750℃-800℃
Burning time 90min (recommended) Burning time 90min (recommended)
Additional voltage Rated voltage (min. 100V) Rated voltage (min. 100V)
Fire resistance grade A (Grade IA~IVA) I~IV
3. Fire-resistant cables and flame-retardant cables
Fire-resistant wires are a general term for wires and cables with fire-resistant properties, and are usually divided into flame-retardant wires and cables and fire-resistant wires and cables. The general public can easily confuse flame retardant cables and IEC 60331 fire-resistant cables.
However, flame-retardant cables have many advantages that are more suitable for chemical companies, such as low halogen, low smoke and flame retardant. Generally speaking, fire-resistant power cables can replace flame-retardant cables, but flame-retardant cables cannot replace fire-resistant cables. Below ZW Cable briefly introduces their differences and characteristics.
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. The flame retardant principle of halogen-free cables relies on the precipitation of water to reduce the baking temperature to extinguish fires. Fire-resistant cables rely on the fire-resistant and heat-resistant properties of the mica material refractory layer to ensure that the cable can work normally in the event of a fire.
As a new technology, the much-criticized cable is a representative of fire-resistant cable. Its principle is that the cable can form a self-supporting ceramic body in the flame, which has a certain strength and can be used in the flame. The cable will not be damaged at temperatures between 650 and 1000°C. Therefore, fire-resistant cables produce very little smoke in a fire and are halogen-free, which is of great help to the environment. Moreover, the cable is easy to install, so many customers are willing to buy it.
Fire-resistant cables and flame-retardant cables differ in structure and materials.
The basic structure of flame retardant cables is:
The insulation layer is flame retardant.
Both the inner and outer sheaths are made of flame retardant materials.
The tape and filler are made of flame retardant materials.
Fire-resistant cables add a fire-resistant layer between the conductor and the insulation layer. A fire-resistant layer can be added to the structure of a fire-resistant cable to form a fire-resistant and refractory cable, but in practical applications, this is not necessary. Because the fire-resistant layer of a fire-resistant cable can usually be wrapped directly on the wire using different refractory materials. It can resist burning for a long time, ensuring the normal operation of the production line even if the polymer is burned at the applied flame.
The characteristic of flame-retardant wires is to delay the spread of flames along the cables so that the fire will not expand. Due to its lower cost, fire-resistant cables sell very well.
Fire-resistant cables can maintain normal operation for a certain period of time under flame burning conditions and maintain the integrity of the line. Fire-resistant cables produce less smoke when burning, especially the use of refractory materials, which make them fire-resistant and flame-retardant. Especially in the case of burning, the cable can still maintain its integrity when sprinkled with water to extinguish the fire. Wired operation.
4. Where to buy fire-resistant cables
The wire and cable industry is a typical manufacturing industry; raw material prices account for 70% to 80%. Therefore, the quality of raw materials greatly affects the quality of wire and cable products, and some companies can provide ultra-low-price products.
Some companies can provide low-price products, but only in terms of raw materials, the product quality is very poor. The rise and fall of copper prices largely determines the price of wires and cables.