Flame-retardant cable is a cable that can stop the spread of fire. Specifically its requirements are in the specified test conditions, the cable specimen is ignited, and after the withdrawal of the fire source, the spread of flame only within the limits. And the residual flame in a limited period of time to extinguish themselves.
The fundamental characteristic of flame-retardant wires is that they can be burned in case of fire and cannot operate normally, but they can stop the spread of fire. In the event of a fire, flame-retardant cables are able to confine the combustion to a localized area. This can save various other equipment from causing more damage.
The combustion of cables is due to external heating and the production of flammable gases. To achieve flame retardancy, the three elements that cause combustion, namely combustible gases, heat and oxygen, must be suppressed. Therefore, the general method used for flame-retardant wire and cable is to add halogen-containing halides and metal oxides to the sheath material.
But containing halogen means that in the cable burning will release a large amount of smoke and halogen acid gas. Rescuers need to put on gas masks to approach the scene to put out the fire, which is not conducive to fire fighting and rescue work. In addition, hydrogen halide gas and water in the air once the reaction, that is, the generation of hydrogen halide acid. This substance can seriously corrode the instruments and equipment, buildings.
With the continuous improvement of the level of science and technology, the issue of flame retardant has been further developed from the past halogen flame retardant to low-halogen, halogen-free flame retardant. Low smoke zero halogen cable is composed of halogen-free thermoplastic or thermosetting materials (materiales de termopar). It can reduce the toxic and corrosive gases produced during combustion.
The use of flame retardant cables
The flame retardancy of cables in multiple dense configurations should be tested by the bundle cable burning test method. It is necessary to select the category that meets the requirements according to the cable configuration, the required prevention of catastrophic accidents and the principle of economy and reasonableness.
In the event of a fire in places that need to maintain power for a period of time, fire-resistant protective cables should be selected. Such as fire, alarm, emergency lighting and generator set emergency shutdown of the preservation of power and other important circuit is best to choose fire-resistant cable.
Cable fire protection
When the number of cables is small, fireproof paint and tape can be added to the cables, or the cables can be worn in fireproof tubes. When there are more cables in the same channel, it is advisable to lay them in fire-resistant slot boxes. In the environment without combustible dust available semi-enclosed. When the cable protection section laid on the bridge is not long, it can also be used fire-resistant package. In tank areas, high-temperature places and other cases with high fire resistance requirements, non-combustible mineral insulated cables (cables aislados minerales) can be used. Self-volume oil-filled cable can take buried sand laying.
In dense places with high security requirements of the cable or closed channel, should be equipped with automatic fire detection and alarm devices suitable for the environment. Open oil-filled cable oil supply system, should be equipped with automatic fire alarm and lockout devices that reflect the state of oil injection. Underground public facilities cable dense parts, multiple oil-filled cable terminal settings and other places with high security requirements, can be equipped with water spray fire extinguishing facilities.