When selecting a cable type, a common question is: which should you choose, FRLS or HFFR? Technically, this comparison is not quite precise.
FRLS is a designation for a finished cable. HFFR describes a halogen-free flame-retardant polymer compound. It is therefore more accurate to compare reduced-fire-hazard PVC compounds used in LS and FRLS cables with halogen-free HFFR compounds used in HF and FRHF cables.
For a manufacturer, these are two different routes. The first allows it to retain PVC, its existing equipment and the basic logic of its formulation. The second requires a switch to a highly filled polyolefin compound and effectively means developing a new material platform.
Revada Plastic is developing both areas. Revaguard RG69P is a key product for upgrading existing PVC formulations. For new projects that require the absence of halogens, the company is developing a range of components for HFFR compounds.
FRLS and HFFR: Defining the Terms First
Under GOST 31565, the FRLS designation applies to fire-resistant cables that do not propagate flame when installed in groups and have reduced smoke and gas emission.
The FR suffix stands for Fire Resistant: the cable can maintain circuit integrity when exposed to fire. This characteristic depends on the design of the finished cable and is verified by specific circuit-integrity tests. It cannot be achieved by a single additive in the sheath or insulation.
HFFR, or Halogen Free Flame Retardant, refers to a class of halogen-free flame-retardant compounds. An HFFR material can be used in an HF or FRHF cable. Whether the cable carries the FR suffix depends on the design of the whole cable, not just its polymer compound.
What the Polymer Compound Determines
The sheath or insulation formulation affects:
- flame propagation;
- smoke generation;
- the content and corrosive effects of evolved gases;
- mechanical and electrical properties;
- material aging;
- extrusion throughput and stability.
Different characteristics are assessed using different methods. The IEC 60332 series evaluates flame propagation, IEC 61034 is used to measure smoke density, IEC 60754-1 determines the amount of halogen acid gas evolved, and IEC 60754-2 assesses the acidity and conductivity of combustion gases.
Passing one test does not automatically confirm all the other properties of a cable.
PVC Compounds Retain Significant Processing Advantages
A plasticizer in a PVC compound makes it possible to adjust hardness, flexibility, low-temperature performance, electrical properties and processability. Manufacturers of cable compounds are familiar with this technology and have suitable equipment.
However, plasticizers increase the share of combustible organic material in the compound. Meeting flame-propagation and smoke-generation requirements calls for a properly designed flame-retardant system.
Antimony trioxide (ATO) has long been one of its main components. It works effectively as a synergist in a halogen-containing PVC matrix, but its high price and unstable availability have made standard powdered ATO one of the riskiest components in the formulation.
Why Reliance on Powdered ATO Should Be Reduced
Since September 2024, China has imposed export controls on certain antimony materials. Shipments of controlled products require an export license and information on the end user and intended use. This is not a blanket ban, but it increases buyers’ dependence on licensing and current trade policy.
The antimony supply chain remains concentrated. According to the USGS, China accounts for a substantial share of antimony mining and global trade in antimony and its oxides. Restrictions imposed by a single country can therefore have a noticeable effect on the material’s availability and cost.
For processors, this means:
- high and volatile formulation costs;
- more difficult long-term planning;
- the need for safety stocks;
- the risk of delivery delays;
- the possible need for urgent reformulation.
At the same time, eliminating antimony entirely from an existing PVC compound is not always technically or economically realistic. A more practical first step may be to stop using standard powdered ATO as a separately added component and switch to a combined system with a lower ATO content.
Revaguard RG69P: More Efficient Use of the Antimony Component
Revaguard RG69P is a combined flame-retardant masterbatch for PVC based on antimony trioxide. According to the product specification, its ATO content does not exceed 70%. The system also contains components intended to address smoke generation.
Its purpose is to retain the effective antimony synergism, reduce the amount of powdered ATO added separately and combine several functions in a ready-to-use masterbatch.
For an existing PVC formulation, this offers the opportunity to:
- retain the polymer base and the main processing technology;
- reduce the content of pure ATO at a comparable initial dosage;
- simplify handling of the flame-retardant system;
- address both the compound’s flame resistance and smoke generation;
- evaluate economics based on the cost of a formulation that has passed testing, rather than the price per kilogram of additive.
RG69P does not eliminate exposure to the antimony market entirely. But it allows the antimony component to be used more efficiently and reduces the formulation’s reliance on separately dosing powdered ATO.
HFFR: A Different Route, Not a Different Additive
If the specification requires a halogen-free material and low corrosivity of combustion products, upgrading a PVC formulation is not enough. A switch to an HFFR compound is necessary.
HFFR compounds are usually based on EVA, polyethylene or polyolefin blends. ATH or MDH often provides the flame-retardant function. In conventional EVA/ATH systems, the mineral filler content can reach 60–70% of the compound by weight.
Such a high loading creates several related challenges:
- it increases viscosity and the load on equipment;
- it makes dispersion more difficult;
- it reduces elongation and may impair strength;
- it increases sensitivity to moisture;
- it affects surface quality and line throughput.
HFFR quality therefore depends on more than a single mineral flame retardant. The polymer matrix, filler particle-size distribution and treatment, crosslinking agents, antioxidant system and processing aid package all matter.
Revada Plastic’s Two Areas of Focus
Revada Plastic does not offer standard powdered ATO as a standalone product.
For existing PVC compounds, the company focuses on Revaguard RG69P. This is a key product for customers who want to reduce their use of powdered ATO, retain their PVC platform and evaluate a more functional form of flame-retardant system.
PVC formulation development also takes into account:
- Reapak and Revastab stabilizers;
- the plasticizer system;
- the lubricant balance;
- filler content;
- requirements for mechanical and electrical properties.
