IMPORTANT FACT:
When standard PVC burns it gives off a number of poisonous gases in particular hydrogen chloride (HCl), which, when combined with moisture forms hydrochloric acid. The damage caused by burning PVC is two-fold; firstly, dense smoke will obscure exit routes with fumes choking people. The second and less recognized problem is that the acid gas produced in the fire permeates electronic equipment, settling on and corroding printed circuit boards and over a period of time can cause random, unpredictable failure.
Low smoke zero halogen or low smoke free of halogen (LSZH or LSOH or LS0H or LSFH) is a material classification typically used for cable jacketing in the wire and cable industry. LSZH cable jacketing is composed of thermoplastic or thermoset compounds that emit limited smoke and no halogen when exposed to high sources of heat.
Most network cables are insulated with polyethylene, PVC or Thermoplastic Urethane (TPU) . In a fire, a halogen-containing plastic material releases, e.g. hydrogen chloride, a poisonous gas that forms hydrochloric acid when it comes in contact with water. Designated Halogen-free cables, on the other hand, do not produce a dangerous gas/acid combination or toxic smoke when exposed to flame.
Low smoke zero halogen cable reduces the amount of toxic and corrosive gas emitted during combustion. This type of material is typically used in poorly ventilated areas such as aircraft or rail cars and DATA centres. Low smoke zero halogen is becoming very popular and, in some cases, a requirement where the protection of people and equipment from toxic and corrosive gas is critical.