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3. Hot water immersion method
Fire-resistant wire and cable can still maintain the normal working of the line for a period of time under the burning conditions, that is, if a fire breaks out, the fire-resistant cable will not burn for a while, and it can still maintain the normal power supply for a period of time. This characteristic determines that the fire-resistant wire plays a major role in modern cities and industrial buildings because, once a fire breaks out, the power supply circuits for control, supervision, guidance, and alarm systems must maintain normal operation.
Staff need to pay attention to the following questions when installing fire-resistant wires:
In the event of a fire accident, the number of joints in the device should be reduced as much as possible to ensure that the line can work properly in a fire. If you need to make branch wiring, handle the joints to prevent fire.
A fire-resistant cable is a cable that can operate safely for a certain period of time in the presence of a flame. This characteristic determines that the fire-resistant cable plays an important role in modern cities and industrial buildings, because once the fire occurs, the power supply circuits of the system such as control, monitoring, guidance, and alarm must maintain normal operation.
Fire-resistant cables are mainly used in power supply circuits such as emergency power supply to user fire-fighting equipment, fire alarm equipment, ventilation and smoke exhaust equipment, guided lights, emergency power sockets, and emergency elevators.
Staff should pay attention to the following issues when installing fire-resistant cables:
1. When fire-resisting cables are used in cable-intensive cable tunnels, cable mezzanines, or in flammable places such as near oil pipes and oil depots, Class A fire-resistant cables should be used first. When these conditions are removed and the number of cable configurations is small, Class B fire-resistant cables should be used.
2. Fire-resistant cables are mostly used for the power supply circuit of emergency power supply and require normal operation in case of fire. As the ambient temperature rises rapidly during a fire, in order to ensure the transmission capacity of the line and reduce the pressure drop, for a circuit with a long power supply line and strictly limiting the allowable pressure drop, the section of the fire-resistant cable should be enlarged at least one step.
3, fire-resistant cables can not be used as high-temperature cables.
4. In order to reduce the probability of failure of cable joints in a fire accident, the number of joints should be minimized during installation to ensure that the line can work normally in a fire. If you need to make branch wiring, handle the joints to prevent fire.
1. Product name identification method
Cables - Low-smoke halogen-free flame-retardant polyethylene insulated low-smoke halogen-free flame-retardant polyethylene sheathed power cables. Imitation products generally have different names, such as polyethylene insulated low-smoke halogen-free flame-retardant power cables and so on.
2. Burning of the epidermis
The insulation layer should not be significantly sunken by using a soldering iron. If there is a large depression, there is a defect in the material or process used for the insulation layer. Under normal circumstances it should be difficult to ignite, after a long time of burning the insulating layer of the cable is still relatively complete, there is no smoke and pungent odor, while the diameter has increased. If it is easy to ignite, it can be determined that the insulating layer of the cable is not using a low-smoke halogen-free material (most likely polyethylene or cross-linked polyethylene material). If there is a large amount of smoke, it means that the insulating layer uses a halogen-containing material. If the insulation surface is severely detached after a long period of combustion and the diameter does not increase significantly, it means that the proper irradiation cross-linking process has not been performed.
If the core or cable is immersed in hot water at 90°C, the insulation resistance will not drop rapidly and stay above 0.1MΩ/Km under normal conditions. If the insulation resistance drops sharply or even below 0.009MΩ/Km, it means that it has not been treated with an appropriate irradiation cross-linking process.
The above is the Kexian cable to share the issues that need attention for the installation of fire-resistant cables and hopes to help everyone.