In industry, choosing the right sealing material is crucial to ensure the reliability of equipment exposed to extreme chemical environments and high temperatures. FFKM (Perfluoroelastomer) is often the material of choice due to its exceptional properties, but many variations exist on the market, offered under different brands and references. Finding an appropriate FFKM equivalent for a specific application requires considering several criteria: commercial brands, compound numbers, allowable temperatures, certifications, and the type of fluid in contact.

1. Finding an FFKM Equivalent by Commercial Brand

Several major manufacturers offer their own FFKM formulations under registered trademarks. Here’s an overview of the main references:

• CHEMRAZ (Green Tweed): known for its highly chemical- and high-temperature-resistant compounds, often used in pharmaceutical and chemical industries.

• SIMRIZ (Freudenberg): offers a range of FFKM products for various applications, including process chemistry, semiconductors, and food industries.

• ISOLAST (Trelleborg Sealing Solutions): specializes in solutions for high-temperature and high-pressure applications with excellent chemical resistance.

• KALREZ (DuPont, now Chemours): arguably the most iconic brand on the market, with products renowned for broad chemical and thermal compatibility.

• Parofluor (Parker Hannifin’s Seal Group): designs FFKM compounds resistant to harsh chemical environments, notably in fine chemicals and oil & gas sectors.

When searching for an equivalent, it is important to first identify the original brand and performance level, then find an alternative from another brand with similar or superior characteristics.

2. Finding an Equivalent by Compound Number

Each FFKM product is manufactured from a specific compound, combining a base elastomer (such as Technoflon® PFR94 from Solvay) with various additives: vulcanizing agents, accelerators, reinforcing fillers, plasticizers, etc.

Each compound has a unique identification number that defines its performance:

• Example: Kalrez 6375 is often used for general chemical applications, while Kalrez 4079 is preferred for higher thermal resistance.

• Simriz 481 is known for wide chemical resistance and good thermal stability.

• Isolast J9503 is designed for very high-temperature environments.

Thus, when finding an equivalent, it is crucial to identify:

• The chemical base of the rubber (type of FFKM polymer),

• The nature and proportion of additives,

• The mechanical and chemical performance after vulcanization.

Some manufacturers provide cross-reference charts to help users select an appropriate equivalent.

3. Finding an Equivalent by Allowable Temperature

Thermal resistance is a key criterion:

Note: these values are indicative and may vary depending on the actual environment (pressure, chemical exposure, thermal cycles, etc.).

When searching for an alternative, ensure that the new compound offers at least the same, if not a higher, thermal range as the original material.

4. Finding an Equivalent by Certifications

Depending on your industry, specific certifications may be mandatory:

• FDA (Food and Drug Administration) for food contact,

• USP Class VI for pharmaceutical applications,

• ISO 23936-2 and NORSOK M-710 for oil and gas industries,

• ASTM D1418 and other standards to recognize elastomer types.

Not every FFKM compound is certified for all applications. If you operate in regulated sectors (food, pharmaceutical, semiconductor, oil & gas), it is critical to choose an equivalent compound with the same certifications as the original product.

5. Finding an Equivalent by Nature of the Contact Fluid

Chemical compatibility is often the most critical element in selecting an FFKM material:

• Strong acids (e.g., concentrated sulfuric acid): require a highly fluorinated FFKM such as Kalrez 6375 or Chemraz 505.

• Organic solvents: FFKM with excellent resistance to hydrocarbons, ethers, and esters.

• Amines and hot amines: specific formulations resistant to degradation, such as Kalrez 4079 or Simriz 498, are required.

• Aggressive mixtures (water, solvents, high temperature): compounds designed to minimize swelling and prevent seal extrusion under pressure.

Each fluid poses specific risks:

• Excessive swelling → Loss of sealing through extrusion,

• Chemical degradation → Cracking, embrittlement,

• Loss of elasticity → Failure under stress.

Therefore, it is essential to consult chemical compatibility charts or request lab tests to validate the suitability between the fluid and the selected material.

Conclusion

Finding an FFKM equivalent is a precise process that involves considering numerous parameters: the original brand, compound performance, thermal range, required certifications, and the nature of the contact fluid. To ensure the best choice, it is advisable to work closely with a manufacturer or specialized distributor capable of offering validated alternatives tested under real operating conditions. A poor choice can lead to costly failures, whereas a rigorous selection ensures optimal durability and equipment safety.

To address this issue, research and development have led to the creation of white FFKM seals, which replace carbon black with barium sulfate (SiO₂). These seals retain the benefits of black FFKM while eliminating the risk of visible contamination.

This article explores the differences between black and white FFKM seals, their applications, and why white FFKM is the ideal solution for high-purity industries.