What is a halogen-free cable?
Do you remember the periodic table of the elements from your chemistry lessons? What is known as the seventh main group contains the halogens: the elements fluorine, chlorine, bromine and two others. They are found in many chemical compounds, for example in polyvinylchloride. PVC, as it is known for short, is very durable, which is why it is used in many technical products, as well as for insulation and sheath material in cables. Chlorine and other halogens are often included as additives to improve flame protection. But that has a price. Halogens are harmful to health. For this reason, plastics that do not contain halogens are increasingly being used for cables.
If you want to or have to use these cables, you should look out for the designation "halogen-free". Halogenated plastics can be identified by the chemical elements in their names, such as chlorophenol rubber, fluorinated ethylene propylene, fluoropolymer rubber and more. By contrast, silicone rubber, polyurethane, polyethylene, polyamide, polypropylene, thermoplastic elastomers (TPE), ethylene propylene diene rubber and certain others are halogen-free. They do not contain any heavy metal based stabilisers or softeners, while the additives for flame protection are environmentally safe.
What is the advantage of halogen-free cables?
Halogens are like many other things. They have many positive properties, but unfortunately also a few negative properties. Chlorine, for example, is a good cleaning agent for disinfecting. But halogens can damage health. This is particularly the case when halogenated plastics, particularly PVC, burn. If a fire breaks out, hydrogen halides are released from the plastic. Halogens combine with water, such as the extinguishing water used by the fire brigade or fluid from the mucous membranes, to form acids - chlorine becomes hydrochloric acid, fluorine the highly corrosive hydrofluoric acid, while a mixture of dioxin and other highly toxic chemicals can also be formed. If these get into the respiratory tract, they can cause irritation and lead to death by suffocation, and even people who survive the fire may suffer permanent damage to their health. This is not the case with halogen-free cables. When they are heavily heated or burn, they do not form corrosive acids or harmful gases.
For integrated fire protection, cables should also have flame protection and low smoke generation. The flame protection slows down combustion and propagation of the flame and promotes self-extinguishing. Manufacturers face a dilemma here, as chlorine and bromine are excellent flame retardants, which is why they are often mixed in with plastics for cables. However, because of the health hazards mentioned, this is controversial and is only permitted where no people are in danger. As a result, LAPP has developed materials with a high level of flame protection but without halogens. They also have a low smoke gas density, so they produce less fumes and make it easier for trapped people to find escape routes. They also retain their function for a long time. The ETHERLINE® FIRE high-speed data cable from LAPP retains its function even after two hours in the flames, and continues to transmit data at the full transmission rate for this time. This can be important in buildings with a lot of people, where surveillance cameras provide pictures of the source of the fire. LAPP has a comprehensive range, from halogen-free NYM and NHXMH jacketed cables to ÖLFLEX® control cables, PROTECT-HF shrink hose and fast data cables from the ETHERLINE® brand.
In which applications should halogen-free cables be used?
In short, wherever people or animals are present and where high value material assets are at risk, such as expensive machinery or artworks. What could happen otherwise is clearly demonstrated by the disastrous fire at Düsseldorf Airport on 11 April 1996. There, 17 people died because PVC cables released fumes, as well as toxic dioxins and furans. In the interior of vehicles, such as buses or trams, halogen-free cables are not only sensible, they are actually a legal requirement. Halogen-free materials are also mandatory in public buildings such as airports, hospitals, schools and exhibition halls, where cable bundles are installed in cable conduits or in cable ducts. Specifications for ships, aircraft and public transport must also stipulate halogen-free cables. As a user, you need to look out for halogen-free cable designations indicating compliance with the following standards: IEC 60754-1 (halogen-free), IEC 60754-2 (low corrosiveness and acidity of fire gases), EN 50305 (low toxicity of fire gases), ECE-R 118.01 (fire test in buses).