What is the grade standard of flame retardant cables?

Flame-retardant cables refer to the characteristics that the sample is burned under the specified test conditions and environment. After the fire source is removed, the spread of the flame on the sample is only within a limited range and the characteristics of self-extinguishing, that is, it has the ability to prevent or delay the occurrence and spread of flames. characteristic. The combustion of wires and cables is due to the flammable gas generated by external heating. To make wires and cables flame retardant, three important factors that cause combustion must be controlled: flammable gas, heat and oxygen. Therefore, the general method used for flame-retardant wires and cables is to add halogen-containing halides and metal oxides to the sheath material. From the perspective of flame retardancy, this is a very effective method. However, since these materials contain Halides release a large amount of smoke and hydrogen halide gas when burning. Therefore, when a fire occurs, the surrounding visibility is low, which brings great difficulties to the safe evacuation of personnel and firefighting. Some people may even breathe too much toxic gas. And suffocate to death.

Flame-retardant wires and cables can delay the spread of flames and prevent fire damage from expanding. The cost of flame-retardant wires and cables is not high, because they are currently a type of cable that is widely used, whether it is a single cable or The bundled, flame-retardant wires and cables can well control the flame spread within a certain range, effectively avoid the occurrence of large-scale fires, and improve the fire protection level of construction projects.

1.Indicators of flame retardant cables

(1) IEC flame retardant grade

In order to evaluate the flame retardant performance of cables, the International Electrotechnical Commission has formulated three standards, IEC60332-1, IEC60332-2 and IEC60332-3. IEC60332-1 and IEC60332-2 are used to evaluate the flame retardancy of a single cable when it is laid obliquely and vertically, and IEC60332-3 is used to evaluate the flame retardancy of bundled cables when they burn vertically. When bundled cables are burned vertically, the requirements for flame retardancy are much higher.

(2) IEC60332-1/BS4066-1 flame retardant grade

This is the flame retardant standard for a single cable. The test stipulates that a 60cm-long sample is vertically fixed in a metal box with an open front wall, and a propane burner with a flame length of 175mm is in contact with the cable at a 45-degree angle from a position 450mm from the upper fixed end of the sample. The test is passed if the distance from the burning damaged part of the sample to the lower part of the fixed end does not exceed 50 mm.

(3) IEC60332-3/BS4066-3 flame retardant grade

This is the flame retardant standard for bundled cables. The test stipulates that the bundled 3.5m long cable samples are fixed on the trapezoidal test frame with iron wires, and the number of samples is determined according to the non-metallic materials required by different classifications. The sample is hung vertically in the combustion furnace, and the air is introduced into the combustion furnace through the air inlet on the bottom plate. The propane plane burner contacts the sample with a flame of 750°C. The sample must not ignite within 20 minutes of vertical combustion under the condition of forced air blowing, and the cable will extinguish itself within 2.5 meters of flame spread. IEC60332 has four categories: A, B, C and D, which are used to evaluate the flame retardant performance of cables.

2.The benefits of flame retardant wire and cable

(1) Flame-retardant wires and cables can provide more than 15 times the escape time than non-flame-retardant wires and cables;

(2) The material burned by flame-retardant wire and cable is only 1/2 of that of non-flame-retardant wire and cable;

(3) The heat release rate of flame-retardant wire and cable is only 1/4 of that of non-flame-retardant wire and cable;

(4) The amount of toxic gas produced by combustion is only 1/3 of that of non-flame retardant products;

When choosing to buy flame-retardant cables, you should choose according to the use and specifications, and choose the flame-retardant cables that are suitable for your own use.