Halogens have many uses, and most of us come into contact with them on a daily basis.
Halogens are made from combining fluorine, chlorine, bromine, iodine and astatine.
Halogens are also widely used as flame retardants in a variety of plastics, including the PVC (polyvinyl chloride) that makes up many cable jackets and electronics-related products.
Unfortunately, when it comes to the health of both humans and the environment, halogen-based flame retardants can be a double-edged sword.
Ironically, while these halogen compounds keep plastics from catching fire and spreading flames, they can also release hazardous gases if the plastic actually ignites.
Carcinogenic substances like Polychlorinated Biphenyls (PCBs), Polycyclic Aromatic Hydrocarbons (PAHs), Nitro Polycyclic Aromatic Hydrocarbons and dioxins are all by-products produced when halogenated plastics burn.
These gaseous compounds pose a double threat…not only are they dangerous in vapor form, but they can also condense into caustic acids (such as hydrochloric acid) when they come into contact with water.
Low Smoke Zero Halogen (LSZH) Materials contain absolutely no halogens, but still have excellent flame resistance and produce very little smoke when burned.
LSZH cabling is the safest choice for plenum use and any other applications in which smoke is likely to both build up and come into contact with people, since no harmful toxins are actually released.
Since the 1970s, fire-retardant, LSZH wire and cable has been commercially available for shipboard applications, offshore marine platforms, rapid transit and similar applications where people are present in confined areas.
When combined with other fire prevention and suppression practices, fire-retardant LSZH cables can help minimize fire-related deaths and property damage.
Because LSZH cables are low-smoke, people can make a quicker and easier escape in the event of a fire.
There is far less smoke to limit their ability to see and breathe, allowing them to get out with less trouble.
Less smoke also leads to less property damage caused by soot.
These qualities make LSZH cable desirable and common for applications where people are present in poorly ventilated or confined spaces, like airplanes, rail cars, or offshore marine platforms.
Using LSZH cable is a safety precaution as well as a method of fire prevention. And as a bonus, LSZH cables have a relatively low coefficient of friction, making for easy installation.
Although LSZH cables have some important benefits, there is a trade-off.
To qualify as low smoke zero halogen cable, the jacket must have a high percentage of filler material.
This means that the jacket will likely be less chemical and water-resistant and have poorer mechanical and electrical properties than a non-LSZH cable jacket. LSZH cables are also more likely to experience jacket cracking during installation, so special lubricants are needed to avoid damage.
Overall, LSZH cable is a good choice when fire safety is a main concern, and some electrical and mechanical properties can be sacrificed in exchange.
LSZH cable is also commonly called: low smoke and fume (LSF), low smoke halogen free (LSHF), and low smoke zero (0) halogen (LS0H).
Low Smoke Zero Halogen cable also has the added benefit of complying with the European Union’s Restriction of Hazardous Substances (RoHS) directive and similar North American safety and environmental standards.
Source : Wire Wisdom and cableorganizer
(this article written for 1BINA.my)