Material

FFKM (Perfluoroelastomer)

FFKM (Perfluoroelastomer) replaces essentially all hydrogen atoms on the polymer backbone with fluorine, achieving near-PTFE-level chemical inertness while retaining the elastic recovery needed for reliable sealing. Commercially introduced by DuPont as Kalrez® in the 1970s, FFKM is now also produced under trade names such as Chemraz® (Greene Tweed), Perlast® (PPE / Idex), Simriz® (Freudenberg), and Isolast® (Trelleborg). With resistance to more than 1,800 chemicals and continuous service ratings up to 327 °C, FFKM is specified where no other elastomer will survive the process chemistry, temperature or regulatory requirements — in semiconductor fabrication, pharmaceutical reactors, oil-and-gas wellheads and chemical processing — at a correspondingly higher cost that is justified by reduced downtime and contamination risk.

FITCO high-performance sealing components

High-performance sealing components for demanding service.

Material Data Sheet

Temperature range

-15 °C to +300 °C (+327 °C intermittent) (grade dependent; low-temp grades to -26 °C)

Hardness range

65–90 Shore A

Tensile strength

10–18 MPa (compound dependent)

Elongation at break

100–200 %

Compression set

12–30 % (at 200 °C × 70 h, compound dependent)

Resists

Near-universal chemical resistance — acids, bases, ketones, esters, amines, steam, solvents, oxidisers, fuels, plasma environments (>1,800 chemicals)

Avoid with

Fluorinated solvents and certain perfluorinated media at high temperature; cost sensitivity

Standards

ASTM D1418 (FFKM designation), ASTM D2000, ISO 1629

Approvals

FDA 21 CFR 177.2600, USP Class VI, EU 1935/2004, 3-A Sanitary (compound dependent)

Compound grades

FFKM compound selection guide

FFKM compounds are engineered for specific service environments. Selecting the right grade is critical — a general-purpose FFKM that excels in chemical immersion may not deliver optimal performance in high-temperature or plasma-etch conditions.

Compound Type	Kalrez® Equivalent	Max Temp	Key Properties	Typical Application
General Purpose	Kalrez® 6375	300 °C	Broad chemical resistance, low compression set (12–15 %)	Chemical processing, CPI, petrochemical
High-Temperature	Kalrez® 4079	316 °C	Superior heat ageing, tensile 15–18 MPa	Semiconductor etch & CVD chambers, hot gas
Plasma / Ultra-Clean	Kalrez® 7075	300 °C	Ultra-low outgassing, plasma-etch resistant	Semiconductor wet-etch, ion implant, CMP
Extreme Temperature	Kalrez® Sahara	327 °C	Highest continuous service temperature	Downhole tools, steam service, exhaust systems
Low Temperature	—	260 °C	Flexible to -26 °C (Tg improvement)	Cryogenic transfer, LNG, aerospace
FDA / Food-Grade	Kalrez® 6221	300 °C	FDA, USP Class VI, EU 1935/2004 compliant	Pharmaceutical, food & beverage, biotech

Kalrez® is a registered trade mark of DuPont. FITCO supplies equivalent FFKM compounds matched to application requirements.

Advantages

Why specify FFKM

Near-Universal Chemical Resistance

Resists more than 1,800 chemicals including concentrated acids, bases, ketones, esters, amines, aldehydes, oxidisers and aggressive solvents — media that attack all other elastomers.

Extreme Temperature Service

Continuous use to 300 °C with grades rated to 327 °C intermittent. Retains sealing force after prolonged heat exposure with compression set as low as 12 %.

Plasma & Outgassing Resistance

Ultra-clean grades withstand aggressive plasma-etch and CVD chamber environments with minimal outgassing, critical for semiconductor yield and wafer purity.

Low Contamination

Fully fluorinated backbone means negligible extractables and leachables, meeting FDA 21 CFR 177.2600, USP Class VI and EU 1935/2004 for pharma and food-contact applications.

Steam & CIP Compatibility

Withstands repeated SIP/CIP (Steam-In-Place / Clean-In-Place) cycles at 150 °C+ without degradation — a key advantage over FKM and silicone in bioprocessing.

Long Seal Life

The premium cost is offset by dramatically extended seal life — often 5–10× longer than FKM in aggressive service — reducing unplanned downtime, maintenance cost and process contamination.

Limitations

Where FFKM is not the best choice

Cost

FFKM is the most expensive elastomer — 20–50× the price of FKM by weight. It is justified only where the application genuinely demands universal chemical resistance or extreme temperature, and where downtime cost exceeds seal cost.

Low-Temperature Stiffness

Standard grades stiffen below -5 °C to -15 °C (glass transition), limiting cold-temperature sealing. Specialty low-Tg grades extend service to -26 °C but sacrifice some chemical breadth or upper temperature rating.

Limited Elongation

Elongation at break (100–200 %) is lower than FKM or NBR, requiring careful gland design to avoid over-stretch during installation — FITCO provides AS568 and ISO 3601 gland recommendations for every FFKM order.

Fluorinated Solvents

Certain perfluorinated media (fluorinated solvents, select refrigerants) can swell FFKM at elevated temperatures. Application-specific compound testing is recommended for unusual fluorinated media.

Applications

Where FFKM seals are used

Semiconductor & Electronics

Plasma-etch chamber seals, CVD/PVD gate valves, wet-bench chemical delivery, ion implant, CMP slurry handling. Ultra-clean FFKM grades minimise particle contamination and outgassing to protect wafer yields.

Oil & Gas / Petrochemical

Downhole completion tools, wellhead valves, HPHT (High Pressure High Temperature) service, sour-gas (H₂S) environments, refinery reactor seals — anywhere FKM's temperature or chemical limits are exceeded.

Pharmaceutical & Biotech

Reactor vessel seals, transfer-line connections, chromatography columns, valve assemblies subject to repeated SIP/CIP sterilisation with aggressive cleaning agents. FDA and USP Class VI compliant grades available.

Chemical Processing & Aerospace

Aggressive solvent, acid and oxidiser duty in CPI plants; turbine and auxiliary-power-unit seals in aerospace where extreme heat and fuel/hydraulic-fluid compatibility converge.

Available as