As industries focus on fire safety, reduced toxicity, and environmental compliance, the selection of appropriate cable materials with no halogens is becoming increasingly important. These advanced compounds, especially LSZH (Low Smoke Zero Halogen) and HFFR (Halogen-Free Flame Retardant) systems, are a groundbreaking change in the way that cable jackets and insulation behave in fire scenarios, when compared with the likes of PVC—halogenated plastics.
As an example, in Hulk Electric, a company with more than 15 years manufacturing high performance industrial cables, we daily use these materials and are able to provide reliable solutions for automation, robotics, and infrastructure projects. This article guides you through the chemistry, performance and practical aspects behind the switch from halogenated alternatives.
What Do We Mean by “Halogen-Free” and “LSZH” in Cable Materials?
Halogen-free cable materials are composed of materials that do not contain chlorine, bromine, fluorine, or iodine. They do not emit corrosive halogen acid gases when burned, like traditional PVC products. The term LSHZ refers to formulations specifically designed to produce minimal smoke and contain no halogens and are suitable for use in confined or high occupancy areas.
The term designations are used mostly for the jacket and insulation compounds but not for the conductor or shielding.
Common Abbreviations and Material Classes (LSZH, LS0H, LSHF, HFFR, ZHFR)
There are a number of terms that are shared between engineers:
- LSZH / LS0H / LSHF: Low Smoke Zero Halogen (or Low Smoke Halogen Free) — indicate “low smoke” and “no halogen.
- HFFR: Highlights flame-retardant performance without the use of halogens.
- ZHFR is a zero halogen flame retardant.
There are regional differences, but emphasis should be placed on proven test data, not labels, for smoke density, acid gas emission, and flame spread.
Halogen-Free Materials Used in Cable Jackets and Insulation
Polyolefins (PE, PP), EVA, EPR and EPDM are common base polymers. Mineral fillers can be used at high levels in these halogen-free cable backbones, keeping the electrical and mechanical properties of the cable at acceptable levels for use in industrial, building and data cables.
LSZH Compounds – Low Smoke, Zero Halogen Polyolefin Systems
LSZH cable compounds are a variety of polyolefin compounds that are formulated to comply with low smoke and zero halogen standards. They are used in jackets and insulation in industrial automation, building wiring, and energy.
How LSZH Polyolefin Compounds Are Built
The following are a typical LSZH compound:
- Base polymer (polyolefin or thermoplastic elastomer) free of halogens.
- Fillers that are mineral based and flame retardant, like Aluminium Hydroxide (ATH) or Magnesium Hydroxide (MDH).
- Stabilizers, processing aids and additives for UV, chemical or mechanical enhancement.
Compounding is a compromise between flame retardancy, flexibility and ease of processability for extrusion onto cable.
Fire Behaviour of LSZH Compounds – Smoke and Gas Profile
Materials made of LSZH are less dense, lighter-colored, smoke with high visibility, without corrosive halogen acids during fire. This is a marked difference from PVC which produces a thick black smoke and toxic gases such as hydrogen chloride.
This type of performance is essential in public buildings, transport hubs, data centres and control rooms where it could interfere with evacuation in the event of a fire, and could cause corrosion to sensitive equipment.
HFFR Cable Materials – Halogen-Free Flame-Retardant Systems
Halogen-free, flame retardant (HFFR) cable materials constitute an essential group of halogen-free materials. They are effective flame retardants, which are mineral fillers, rather than halogenated additives.
What “HFFR” Actually Means in Cable Compounds
Unlike brominated or chlorinated systems, HFFR compounds contain halogen-free polymers with inorganic fillers to effectively suppress flames, reduce smoke and prevent toxic/corrosive gas release.
Advantages of HFFR Compounds in Safety and Environment
Some of the advantages are reduced toxicity, less corrosion issue for electronics and infrastructure, and easier incorporation of sustainable objectives. These materials can be used to slow the spread of fire and allow for better routes to escape.
Fire-Safety and Environmental Drivers Behind the Shift Away from Halogenated Plastics
There are documented issues to overcome with this industry change regarding the significant smoke, release of toxic gases, and corrosive by-products that hinder fire response and post-fire cleanup.
Regulatory Trends – RoHS, REACH and Bans on Halogenated Flame-Retardants
RoHS is limited to certain substances such as PBB and PBDE, while REACH is to expand chemical safety evaluations. Multiple jurisdictions have begun to restrict the use of halogenated FRs in electronics and building materials, favoring the use of LSZH and HFFRs.
Health, Environment and Post-Fire Cleanup Considerations
Materials that are halogenated can release long-lasting toxins and acids that impact health and lengthen the cleanup process. Halogen-free solutions reduce those effects to help foster a greener infrastructure and compliance.
Mechanical and Processing Trade-Offs of LSZH and HFFR vs Traditional PVC and PE
LSZH and HFFR compounds provide better fire and environmental properties, but come with certain compromises.
Tensile Strength, Flexibility and Density Considerations
The higher the filler level, the more dense the material will be, which can lead to lower elongation at break, and different flexibility as compared to PVC. Specific grades are matched to application requirements for optimal cable-handling and durability.
Processing and Self-Extinguishing Behaviour
Extrusion parameters might need to be adjusted and surface finish can be different for such compounds. Highly flame resistant, formulation and testing ensure that they meet the self-extinguishing and overall performance requirements.
Practical Implications for Cable Specifiers and Design Engineers
When reading and specifying cables, it is helpful to be familiar with these materials.
What to Look for in LSZH/HFFR Datasheets and Certificates
Focus on smoke density, acid gas emission, mechanical properties (tensile, elongation), and pertinent third-party certifications. Ask for detailed test reports, not marketing hype.
Matching Compound Choice to Application (Buildings, Transport, Industrial, Data)
Depending on the application, tougher LSZH jackets can be used for industrial applications, or a specialized flexible grade of HFFR can be used for dynamic or shipboard applications. Match options to fire risk, mechanical requirements and local regulations.
Looking Ahead – How Halogen-Free Cable Materials Are Shaping Future Designs
LSZH and HFFR technologies are still being developed, with ever better mechanical properties, lower costs, and better environmental performance. In many projects, the use of halogen free materials is now the standard in safety critical applications.
Market and Technology Trends in Low-Smoke Halogen-Free Materials
There is increased demand for LSHF solutions in buildings, transport and renewables. Innovations are related to improved UV/chemical resistance and processability for wider use.
Working with Material and Cable Suppliers on Next-Generation Designs
Work closely with seasoned manufacturers such as Hulk Electric. Provide application information on fire safety requirements, environment exposure, and performance requirements to develop customized halogen-free cable materials that consider safety, reliability, and cost.