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How to choose fireproof materials for fire resistant cables?


Fire resistant cable is a kind of power cable with good fireproof performance, which is widely used in buildings, subways, hospitals, schools and other places with high fire risk. Ensuring the quality of fireproof cables is of great significance for ensuring personal safety and reducing fire accidents.

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The flame-retardant and fire-resistant materials for cables are composed of a series of materials such as flame-retardant light-duty closed tank boxes for cables, light-weight fire-resistant partitions, organic fire-resistant blocking materials, and fire-resistant coatings. It is suitable for fire protection of cables of various voltage levels, and can effectively realize fire-resistant separation of cable channels and prevent cables from igniting and spreading. When our commonly used XLPE power cables are short-circuited or burnt by open flames nearby, the flames will ignite the concentratedly laid cables around them, causing serious impacts. Taking reasonable cable fire prevention measures plays a vital role in preventing the flame spread of cables.

How to choose fireproof materials for fire resistant cables?

The key to the quality of fire resistant cables lies in the selection of materials. First of all, flame-retardant materials that meet the requirements of relevant standards must be selected as insulating layers and sheaths, such as low-smoke and halogen-free materials, which have good fire resistance and can effectively prevent flame spread and smoke release. Secondly, copper or aluminum materials with good quality conductor materials and high electrical conductivity should be selected to ensure the reliability and efficiency of current conduction. Fire-resistant cables are cables that can maintain normal operation for a certain period of time under specified flame conditions, or cables that can maintain circuit integrity under burning conditions.

1. Selection of conductor material and conductive core structure

The melting point of the aluminum conductor is 685°C and the fire-resistant cable test is based on GB/T 19216. The fire supply temperature must reach 750+50°C. Obviously, the aluminum conductor cannot be used as a fire-resistant cable; the melting point of copper is above 1000°C, so it can be used as a fire-resistant cable. conductor.

Copper wire with a cross-section of 1.0mm2 or less, but because the wire core is too thin, it is very easy to break the conductor due to local overheating of the material, thus losing the normal power-on function. Therefore, copper wires of 1.0mm2 and below are not recommended as conductor materials for fire-resistant cables.

It is not easy to make a fire-resistant cable with a fan-shaped core conductor of a cable with a large cross-section, and a round-core conductor is suitable for a fire-resistant cable. The surface of the circular structure is smoother than that of the fan-shaped structure, and the stress is relatively uniform, which will not cause damage to the mica tape. Moreover, the circular structure saves the mica tape compared with the fan-shaped structure, and the cost is low.

2. Selection of mica tape

The classification requirements for fire-resistant cables have been canceled in the national standards. Because the refractory temperature of synthetic mica is higher than that of phlogopite, refractory mica tape can be selected according to customer requirements in actual production. In addition, according to the safety of refractory cables and the stability of refractory cable quality, during the selection process Synthetic mica is recommended.

3. Selection of insulating materials

The commonly used insulating materials for fire-resistant cables are mostly PVC, PE, XLPE, etc., but the effect of using PE and XLPE is better than PVC, because at the high temperature of 750+50°C, the insulating material of the cable has already burned and does not exist, but different insulation materials The residual materials after burning the materials have different effects on the mica tape.

The main components of PVC are PVC resin and CaCO3, which adhere to the outside of the mica tape according to its combustion mechanism. Its combustion solid residue, the mixture of CaO and Cacl2, is in a relatively stable state and adheres to the outside of the mica tape. Internal stress is generated to squeeze the mica tape, which will damage the mica tape and affect the fire resistance.

4. Selection of auxiliary materials

Taping and filling as auxiliary materials for fire-resistant cables are not key materials, but they should be based on the principle of least residue after burning.

 

The quality standards and certification of fire-resistant cables are an important guarantee to ensure their reliable quality. In the process of production and sales, it is necessary to strictly follow the relevant national standards for production, and pass relevant quality certification, such as CCC certification, ISO9001 quality management system certification, etc., to ensure that the products meet the requirements of national and industry standards. Zhengzhou Jinshui Wire & Cable Group produces cable products in strict accordance with international production standards, and actively participates in the formulation and revision of industry associations and related standards to promote the development of the fire-resistant and fire-resistant cable industry and the improvement of standards.