Low smoke zero halogen, referred to as LSZH, LSOH, LS0H, LSFH and OHLS, is the material classification of wire sheath in the wire harness and cable assembly industry. The low smoke zero halogen wire sheath is composed of thermoplastic or thermosetting which has low smoke emission when heated and does not contain halogen itself.
Most of the network cable coating is composed of polyethylene, polyvinyl chloride or thermoplastic polyurethane. In case of fire, chlorinated plastics release poisonous hydrogen chloride, and if it encounters water, it will produce hydrochloric acid. Low smoke zero halogen materials will not release hydrogen halide or other acids when they catch fire.
Low smoke zero halogen materials can reduce the toxic and corrosive gases produced when they burn. Low smoke zero halogen materials are often used in poorly ventilated environments such as airplanes, train cars, or ships. Low smoke zero halogen materials are also commonly used in the railway industry, because there will be high-voltage lines or signal lines that transmit the location of the train below the railway. The use of low smoke zero halogen materials also reduces the accumulation of toxic gases when the line is damaged by fire or short circuit.
In the railway or shipbuilding industry, an important requirement is to protect people and equipment from contact with toxic and corrosive gases. In these occasions, low smoke zero halogen materials are required to be used on the outer layer of wire harnesses and cable assemblies.