FRNC, HFFR, LS0H, LSZH flame-retardant, halogen-free cables

Halogen-free cables are a required staple in a vast number of industrial and infrastructural applications. Over time, different labels for these cables have been established, such as FRNC, HFFR, LS0H, or LSZH. But how meaningful are these abbreviations, and what are the benefits of halogen-free cables compared to products containing halogens? Let HELUKABEL explain.

Halogens (which means "to form salt") include the chemical elements chlorine (Cl), bromine (Br), fluorine (F), and iodine (I). When manufacturing cables, these are used to make certain core insulation and sheathing materials flame retardant. This is where chlorine (which is a component of PVC plastic or chloroprene rubber) and fluorine (which is found in the high-temperature materials FEP, PTFE, and ETFE) come into play. Even bromine is used in flame retardants for cables and wires.

>>See more: HELUKABEL's flame-retardant cables for industrial applications

2.1 What is halogen-free?

The problem is that halogens burn extremely aggressively and emit noxious fumes when ignited. They produce halogen halides which turn into acids when they come into contact with moisture and can cause acid burns in the respiratory tract. Furthermore, the acids that are released can cause metal parts to corrode, damaging machines and even the rebar reinforcements of concrete in buildings. This can result in the need for time-consuming and costly decontamination efforts.

The flame retardancy of cables and wires is, of course, an important criterion for fire prevention measures. There are also a number of applications that explicitly require halogen-free products, which means cables and wires consisting of materials that are free of chlorine, bromine, fluorine, and iodine. Should these cables be ignited, they produce much less acid and smoke, and are less toxic, which substantially reduces the consequential damage to people, buildings, and machines. Poisonous gases such as carbon monoxide are, however, still emitted when halogen-free cables are ignited.

2.2 Applications of flame-retardant, halogen-free cables

Halogen-free cables and wires are required, for example, in buildings where people gather and where valuable material assets must be protected. Examples for this are:

• Building technology: In public buildings such as offices, shopping centres, schools, hospitals, and airports, strong fire and health risk prevention ordinances are in place. Most of the cables and wires in these places are fixed in their installation and do not need to fulfil any special chemical or mechanical requirements. PE or PP-based plastic mixtures are often used here, which are halogen free and flame-retardant, and produce little smoke or toxic gas. They must also often pass bundle burning tests.
• Industrial automation: Machines and plants often require cables and wires with high chemical and mechanical resistance. When used in flexible applications such as in drag chains or in robotics, these loads are especially high. Typically, sheath mixtures based on TPE-O or TPE-U (PUR or Santoprene) are used here. These are also available with halogen-free constructions but are not able to be manufactured to be as flame-retardant or low smoke as cables for building technology.