FFKM (Perfluoroelastomer) O-rings are one of the most reliable sealing solutions available, offering unmatched performance in some of the most demanding environments. Combining extreme temperature tolerance, excellent chemical resistance, and mechanical integrity, FFKM has earned its place in industries ranging from aerospace to chemical processing. 

What is FFKM and Why is It So Effective?

FFKM, or Perfluoroelastomer, is a highly fluorinated version of fluoroelastomer that was first developed in the 1960s. Its unique composition gives it the ability to withstand extreme temperatures ranging from -45°C to +330°C, and makes it resistant to over 1,800 chemicals, including hydrocarbons, oils, fuels, and aggressive solvents. This extraordinary versatility is why FFKM is now used extensively across industries that require the highest standards of sealing performance.

Key Benefits of FFKM O-Rings

1. Exceptional Temperature Resistance FFKM O-rings are designed to perform in both extremely high and low-temperature environments. They can withstand temperatures as low as -45°C (-49°F) and as high as 330°C (635°F). This makes them ideal for industries such as aerospace, automotive, and heavy-duty machinery where temperature extremes are common.
2. Unmatched Chemical Resistance One of the standout features of FFKM is its resistance to a wide range of chemicals. With the ability to resist over 1,800 chemicals, solvents, and plasmas, FFKM O-rings ensure reliable performance even in aggressive environments. This resistance makes FFKM ideal for applications in chemical processing, oil and gas, and semiconductor manufacturing.
3. Superior Permeation Resistance FFKM O-rings are highly resistant to gas and liquid permeation, which can lead to seal degradation and failure. Their ability to prevent permeation helps maintain the integrity of the sealing system, extending the lifespan of the equipment and preventing costly downtime or leaks.
4. Weathering and Ozone Resistance FFKM seals are highly resistant to ozone and weathering, making them perfect for outdoor applications. Whether exposed to fluctuating temperatures, humidity, or UV radiation, FFKM O-rings retain their structural integrity and sealing ability. This resistance is essential in industries like automotive and oil and gas, where outdoor exposure is common.
5. Safety and Non-Flammability FFKM O-rings are typically self-extinguishing and exhibit very low flammability in air due to their fully fluorinated polymer structure. This makes them suitable for applications where fire safety and thermal stability are important considerations.
6. Low Outgassing and Extractables In industries like pharmaceuticals, medical device manufacturing, and semiconductor production, outgassing and particle contamination can cause serious problems. FFKM O-rings feature low outgassing properties, ensuring that they don’t release harmful vapors or particles, which is critical for maintaining cleanliness in high-sterility environments.
7. Outstanding Mechanical Properties FFKM O-rings offer excellent compression set resistance and sealing performance, even under mechanical stress. This makes them ideal for heavy-duty machinery, aerospace, and automotive applications, where maintaining a tight seal under pressure is essential.
8. Suitability for Explosive Decompression FFKM is resistant to explosive decompression, a phenomenon that occurs when a material rapidly decompresses under pressure. This resistance prevents rupture, leaks, and seal failures, making FFKM O-rings highly reliable in high-pressure applications.
9. Customisable Shapes and Sizes FFKM O-rings can be easily customized into a variety of shapes and sizes to meet specific application requirements. Whether you need O-rings, gaskets, or custom seals, FFKM's flexibility ensures a perfect fit for your sealing needs.
10. Ultra-Clean Formulas for High-Sterility Environments For applications requiring the highest levels of cleanliness, such as pharmaceuticals and semiconductor manufacturing, FFKM O-rings are available in ultra-clean formulations. Manufactured in cleanroom environments, these seals are free from contaminants, ensuring the integrity of your processes.
11. We can also supply FFKM with approvals such as:
    • 3-A
    • AED/RGD
    • BfR XXI
    • FDA
    • Low Temperature
    • NORSOK M-710-2
    • NORSOK M-710-3
    • Steam Resistance
    • USP Class VI

Applications of FFKM O-Rings in Different Industries

Given the exceptional benefits of FFKM, it's no surprise that this material is used across a wide range of industries. Here are some of the key applications:

• Chemical Processing: FFKM O-rings are ideal for chemical processing applications, including reaction column seals, chemical fluid handling, and heavy-duty cleaning processes. Their chemical resistance makes them perfect for handling aggressive solvents and chemicals.
• Oil and Gas: In the oil and gas industry, FFKM is commonly used for sealing applications in pump and motor stators, packer elements, and critical sealing parts exposed to hydrocarbons and fuels. Its ability to withstand harsh chemicals and extreme pressure makes it a trusted material for this industry.
• Aerospace: Aerospace applications require materials that can handle extreme temperatures, pressure variations, and environmental stress. FFKM is ideal for use in aircraft engines, seals, and piston rings, where performance reliability is paramount.
• Heavy-Duty Machinery: FFKM O-rings are used in heavy-duty machinery where seals are subject to high mechanical stresses. Industries such as manufacturing, construction, and mining benefit from the durability and performance that FFKM seals provide.
• Automotive: FFKM's resistance to high temperatures, ozone, and a wide range of chemicals makes it a perfect fit for automotive applications. It is widely used in fuel systems, injectors, and high-pressure pumps, ensuring long-lasting, reliable performance in automotive environments.

Why Choose FFKM O-Rings from Polymax?

At Polymax, we specialise in providing top-quality FFKM O-rings and sealing solutions for a wide range of industries. Our FFKM O-rings are manufactured to the highest standards to meet the demanding needs of your applications. Whether you are in aerospace, chemical processing, or automotive, we offer the perfect sealing solution to improve efficiency, reduce downtime, and enhance safety.

We can supply FFKM compounds similar to:

The Polymax team can also work closely with designers and engineers to identify a Polymax compound suited to your specific application. We can support your development process with detailed datasheets, helping you confidently specify the correct material for both current requirements and future designs.

Contact Polymax today to find out how FFKM O-rings can enhance your sealing applications. Let us help you choose the right material and design to meet your specific needs, ensuring performance, reliability, and long-term success. Contact our team on: +44 (0) 1420 474 123 or [email protected] 

Ensuring the Safety and Compliance of Materials for Potable Water

Ensuring the safety and compliance of materials in contact with drinking (potable) water is a critical responsibility for engineers, manufacturers, and contractors in the UK. The Water Regulations Advisory Scheme (WRAS) provides a robust framework to certify materials for potable water use, verifying that products will not compromise water quality, public health, or system performance.

Is WRAS Approval a Legal Requirement?

While WRAS approval itself is a voluntary certification and not a legal requirement, compliance with the Water Supply (Water Fittings) Regulations (or Scottish Byelaws) is mandatory by law.

In the context of O-rings, this means:

• The Legal Risk: Installing a non-compliant O-ring, such as a generic automotive seal, that leaches chemicals or promotes bacterial growth is a criminal offense.
• The Performance Gap: In the UK, compliance is viewed through two lenses: Safety (BS 6920/WRAS) and Reliability (EN 681-1). While WRAS ensures the water stays pure, EN 681-1 (the standard for elastomeric seals) ensures the O-ring is physically strong enough to prevent leaks and structural failure.
• The Practical Solution: Because individual homeowners and plumbers cannot easily perform laboratory tests on a single rubber seal, using WRAS-approved O-rings is the only practical way to guarantee that a component meets the required legal standards for both safety and mechanical integrity.

The regulations state that every water fitting must be of "an appropriate quality and standard." While other certifications (like KIWA or NSF) are also legally valid, WRAS remains the most recognised "stamp of approval" in the UK to ensure your plumbing stays on the right side of the law.

What WRAS Approval Ensures

WRAS certification confirms that materials and components in contact with potable water:

• Do not leach harmful substances into water.
• Maintain taste, odour, and clarity.
• Prevent microbial growth (Standardised via EN 16421).
• Retain structural integrity under normal service conditions (Standardised via EN 681).

Materials undergo rigorous testing, including:

• Chemical extraction testing: Ensures no harmful compounds migrate into water.
• Organoleptic assessment: Evaluates taste and odour impacts.
• Microbial growth testing (EN 16421 / BS 6920-2.6): Ensures the material does not provide a "food source" for bacteria. EN 16421 tests the Enhancement of Microbial Growth (EMG), preventing biofilms that could harbor pathogens like Legionella.
• Mechanical performance (EN 681-1): Verifies hardness, tensile strength, and "compression set" to ensure the seal doesn't degrade over time.

Only materials that meet all criteria are approved, providing confidence in long-term water safety for engineers, contractors, and water authorities.

Scope of WRAS-Certified Products

WRAS certification is relevant to non-metallic components in contact with potable water, including:

• Seals and gaskets
• O-rings
• Cords
• Tubing and hoses
• Sheets and linings
• Rubber mouldings

Checking WRAS Approval

• Verify that a product has a current WRAS approval mark.
• Approvals are valid for 5 years and must be re-evaluated after expiration.
• Formulations can change over time; only verified approvals ensure regulatory compliance.
• Manufacturers display the WRAS Certification Mark on packaging or websites.
• Check out the official Polymax WRAS listings on the WRAS website.

Key point: WRAS approval covers individual products or materials, not an entire manufacturer’s product range.

WRAS vs Global Potable Water Standards

Elastomer and Non-Elastomer Material Comparison

Selecting the correct elastomer or material is critical for WRAS compliance. Only chemically inert, water-stable, and microbiologically safe materials should be used in drinking water systems.

WRAS at a Glance

• Chemical safety (via BS 6920)
• Microbiological safety (via EN 16421)
• Mechanical reliability (via EN 681)
• Regulatory compliance (Water Supply Regulations 1999)

For UK potable water applications, engineers and specifiers should prioritise WRAS-approved Silicone (VMQ) and EPDM, as these consistently meet stringent testing requirements.

Tip: Always verify material WRAS status and consult technical datasheets to ensure safe, compliant, and long-lasting potable water systems.

Get Expert Advice

Our team of experts can help you choose the right materials for drinking water applications, ensuring WRAS compliance and UK regulatory adherence.

Contact us: +44 (0) 1420 474 123 | Email: [email protected]

This article will explain the main differences between Nitrile vs Viton®. Two of the most commonly approved elastomers, Nitrile (popularly referred to as NBR or Buna-N) and Viton® (Fluorocarbon rubber). Both materials are a great choice for general industrial use, they offer excellent compression set resistance and have a versatile set of properties list of applications and properties.

Nitrile vs Viton®

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