LSZH

What is LSZH (Low Smoke Zero Halogen)?

Low smoke zero halogen or low smoke-free of halogen (LSZH or LSOH or LS0H or LSFH or OHLS or ZHFR) 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.

Low-smoke zero-halogen cable considerably reduces the amount of toxic and corrosive gas emitted during combustion. When burned, a low-smoke zero-halogen cable emits a less optically dense smoke that releases at a lower rate. During a fire, a low-smoke cable is desirable because it reduces the amount and density of the smoke, which makes exiting a space easier for occupants as well as increases the safety of firefighting operations.

This type of material is typically used in poorly ventilated areas such as aircraft, rail carriages, tanks, subsea and offshore installations, submarines or ships. It is also used extensively in the rail industry, wherever high voltage or track signal wires must be run into and through tunnel systems. The nuclear industry is another area where LSZH cables have been and will be used in the future. Major cable manufacturers have been producing LSZH cables for nuclear facilities since the early 1990s. Construction of new nuclear plants will almost certainly involve extensive use of LSZH cable. This will reduce the chance of toxic gases accumulating in those areas where personnel are working and the lack of corrosive gases where there are computer-controlled systems will reduce the possibility of wires being damaged by fire resulting in a short circuit fault.

Benefits of LSZH Cables

PVC is a very versatile and cost-effective material. Its main properties and benefits include:

• 1. Low Smoke Generation: LSZH cables produce less smoke when burning in a fire, which improves visibility and enhances evacuation safety. This is particularly important in confined spaces like aircraft, trains, and tunnels.

• 2. Low Toxicity: LSZH cables do not release toxic halogen gases, such as chlorine, fluorine, and bromine, during combustion, significantly reducing the risk of personnel inhaling toxic fumes.

• 3. Low Corrosivity: LSZH cables do not produce corrosive gases when burned, which helps to protect sensitive electronic equipment and instruments from corrosion.

• 4. Improved Safety: The safety features of LSZH cables enhance overall fire safety, facilitating emergency evacuation and firefighting operations.

• 5. Environmentally Friendly: LSZH cables are free of halogenated and other harmful chemicals, making them more environmentally sustainable.

• 6. Broad Application: LSZH cables are widely used in industries with strict fire and environmental safety requirements, such as aerospace, rail transportation, subsea and offshore facilities, and nuclear power plants.

Differences between PVC and LSZH Cables

Physically, PVC and LSZH are very different. PVC cables are very soft; LSZH cables are more rigid because they contain the flame-retardant compound, and they are aesthetically more pleasing.

A PVC cable (made of polyvinyl chloride) has a jacket that gives off heavy black smoke, hydrochloric acid, and other toxic gases when it burns. Low Smoke Zero Halogen (LSZH) cable has a flame-resistant jacket that doesn't emit toxic fumes even if it burns.

LSZH cables usually cost more than the equivalent PVC cable, and certain types are less flexible. LSZH cable does have some restrictions. According to CENELEC standards EN50167, 50168, 50169, screened cables must be halogen-free. However, no similar regulation yet applies to unscreened cables.

PVC cable is commonly used for horizontal runs from the cabling center. You can use it for vertical runs between the floors - but only if the building features a contained ventilation system running through the ductwork. LSZH cable is used between floors in a building. It has a special flame-retardant coating.