As we all know, the burning and deferred burning of an […]
As we all know, the burning and deferred burning of an object must have three elements: flammable, heat and air.
(1) Insulation materials and protective layers of various types of cables that have been widely used so far are mostly flammable organic materials. Although cables with oil, paper, and asphalt as cable materials have been eliminated, many old factories continue to use them. The cables of polyethylene, cross-linked polyethylene, polypropylene, polystyrene, natural rubber and other materials are widely used. The oxygen index of these materials is 19 or below, and generally ignites at 300 ° C to 400 ° C. In addition, the amount of heat generated during combustion is greater than that of coal of the same weight. Therefore, cables made of these materials will not extinguish and ignite once they catch fire. This is the main cause of the spread and expansion of cable fires.
(2) When a large amount of toxic gas in the smoke is generated when a wire or cable is on fire, it will damage human health and cause death.
(3) Wires and cables quickly self-extinguish after a fire, and there are almost no examples of accidents, but this is mainly related to factors such as cable type, quantity, number of layout layers, and environmental conditions.
(4) According to the old standard, the fire test on single PVC cable shows no flame retardancy, but in a large-scale situation where multiple cable groups are laid, once the cable catches fire, a large range of The high temperature causes the cable to form a flame retardation and will not self-extinguish. Under the condition of supplying the same amount of air, the flame retardation speed and flame propagation speed during horizontal laying are smaller than when vertical laying.