The cable has a high resistance to the spread of combustion and fire from short circuits. But burning it in a fire when he is exposed to a flame, can lead to increased toxicity of combustion products. Therefore, their application in subway Western Europe was banned in the late 1970s. To solve the problems associated with the release of HCl and the smoke was created class of cable materials, which do not contain halogens, ie, do not emit corrosive gases and have significantly lower levels of smoke – the so-called tracks. Halogen-free cable arrangement developed from the need to increase their oxygen index values up to about 35 … 40. This is achieved through the introduction of the original polymer flame retardants-hydroxides.

In industrial-scale use of aluminum hydroxide Al (OH) 3 and Mg Mg (OH) 2 synthetic and natural origin. The mechanism of action of flame retardants hydroxides is the large amount of heat absorbed by the emission of water at higher temperatures. The base polymers for industrial halogen-free tracks are mostly copolymers of ethylene: Ethylene-vinyl acetate (EVA), ethylene-acrylate polymers (EMA, EEA, EBA), metallocene ethylene-octene copolymers (mULDPE) and ethylene-propylene copolymers (EPR / EPDM). Modern fire safety requirements is not permitted open wiring with a shell flame retardant. Cable products should be organized by indicators of fire safety in the following types of performance: without execution – cable products, flame retardant in a single gasket; ng – cable products, flame retardant in the lining of the group; ng-LS – cable products, flame retardant in the lining of the group, with low smoke and gas emission; ng-HF – cable products, not flame retardant in the group gasket and do not emit corrosive gaseous products of combustion and smoldering, ng-FRLS – cable products fire-resistant, flame retardant in the lining of the group, with low smoke and gas emission; ng-FRHF – cable products fire-resistant, flame retardant in the group gasket and do not emit corrosive gaseous products of combustion and smoldering, ng-LSLTx – Cable products, flame retardant in the group gasket, low smoke and gas emission and low toxicity of combustion products; ng-HFLTx – cable products, flame retardant in the lining of the group, not emit corrosive gaseous products of combustion and smoldering and low toxicity of combustion products.