FKM/Viton® Rubber: Complete Guide to Properties, Applications, and Supplier Selection (2026)

For engineers and procurement managers specifying high-performance seals, FKM (fluoroelastomer) rubber—commonly known by Chemours’ trade name Viton®—represents the gold standard for demanding sealing applications. Whether you’re sourcing O-rings for aerospace hydraulic systems or valve seats for chemical processing, understanding FKM’s capabilities and limitations is critical to making informed material decisions. This comprehensive guide covers everything you need to know about FKM rubber: from fundamental properties and chemical resistance to manufacturing processes and how to select a reliable supplier in China. —

Table of Contents

1. What is FKM/Viton® Rubber? 2. Key Properties of FKM 3. FKM Material Types and Grades 4. Chemical Resistance Guide 5. Common Applications 6. Temperature and Pressure Ratings 7. FKM vs. Other Elastomers 8. Manufacturing Processes 9. How to Select a Supplier 10. FKM Pricing and MOQ 11. FAQ 12. Conclusion —

What is FKM/Viton® Rubber?

FKM (Fluoroelastomer) is a high-performance synthetic elastomer primarily composed of vinylidene fluoride (VF2) and hexafluoropropylene (HFP). Developed in the late 1950s, FKM has become the material of choice for applications requiring exceptional chemical and thermal resistance. Viton® is the registered trademark brand name for FKM compounds produced by Chemours (formerly DuPont). While “Viton®” and “FKM” are often used interchangeably, it’s important to note that: – FKM is the generic chemical classification – Viton® is a specific brand of FKM from Chemours – Other FKM brands include: Dai-El (Daikin), Tecnoflon (Solvay), AFLAS® (Asahi Glass), and Dyneon (3M)

ASTM D2000 Classification

FKM compounds are classified under ASTM D2000 as: – FK (Traditional FKM, 66-71% fluorine content) – GE (Modified FKM, improved low-temperature performance) —

Key Properties of FKM

FKM’s performance profile makes it ideal for harsh environments:

Property	Value	Significance
Temperature Range	-20°F to +400°F (-29°C to +204°C)	Wide operating range
Fluorine Content	66-71%	Higher = better chemical resistance
Hardness	60-90 Shore A	Versatile durometer options
Tensile Strength	1,400-2,500 psi	Good mechanical strength
Elongation	150-300%	Flexible sealing
Compression Set	15-30% (at 70h @ 200°C)	Good long-term seal memory
Ozone Resistance	Excellent	Outdoor/UV applications
Oil Resistance	Excellent	Petroleum-based fluids
Gas Permeability	Very Low	Effective barrier material

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FKM Material Types and Grades

FKM compounds vary in fluorine content, which directly affects chemical resistance and cost:

Type A (Standard FKM)

– Fluorine Content: ~66% – Temperature Range: -20°F to +400°F – Applications: General purpose, automotive fuels, mineral acids – Cost: $$$

Type B (Improved Acid Resistance)

– Fluorine Content: ~68% – Temperature Range: -20°F to +400°F – Applications: Chemical processing, sour gas applications – Cost: $$$$

Type C (Enhanced Fluid Resistance)

– Fluorine Content: ~70% – Temperature Range: -20°F to +400°F – Applications: Automotive fuels, methanol blends – Cost: $$$$

Type GFLT (Low-Temperature FKM)

– Fluorine Content: ~67% – Temperature Range: -40°F to +400°F – Applications: Cold climates, aerospace – Cost: $$$$$

Type ETP (Advanced FKM)

– Fluorine Content: ~65% – Temperature Range: -40°F to +446°F – Applications: Ethylene oxide, sterilizers, pharmaceutical – Cost: $$$$$

Specialty Grades

– Peroxide-Cured: Improved chemical resistance, lower compression set – Bisphenol-Cured: Standard cure system, good overall properties – ionic-Cured: Fast cycle times, cost-effective —

Chemical Resistance Guide

FKM excels in these environments:

Excellent Resistance ✓

– Petroleum oils and fuels (gasoline, diesel, Jet Fuel) – Mineral acids (sulfuric, hydrochloric, nitric) – Aromatic solvents (toluene, benzene) – Synthetic lubricants (esters, phosphate esters) – Silicone oils and greases – Chlorinated solvents (perchloroethylene)

Limited/Poor Resistance ✗

– Ketones (MEK, acetone) – Esters (acetate, phthalate) – Amines (EDA, DETA) – Hot water and steam (over 200°C) – Glycol-based brake fluids (DOT 3, DOT 4) – Skydrol and phosphate ester hydraulic fluids – Butyrate and acetate solvents ⚠️ Important: Always conduct immersion testing for critical applications. Compound selection significantly impacts chemical compatibility. —

Common Applications

Automotive Industry

– Fuel injector O-rings and seals – Valve stem seals – Crankshaft seals – Transmission seals – Fuel pump O-rings – Turbocharger hose connections

Aerospace

– Hydraulic system seals (Skydrol, phosphate esters) – Fuel system components – Pneumatic seals – Cockpit instrumentation seals – Landing gear hydraulics

Oil and Gas

– Downhole packer elements – Wellhead seals – Subsea Christmas tree valves – Drilling mud seals – BOP (Blowout Preventer) seals

Chemical Processing

– Pump seals and diaphragms – Valve seats – Corrosion-resistant linings – Heat exchanger gaskets – Agitator seals

Pharmaceutical/Food

– Clean-in-place (CIP) seals – Steam sterilizer gaskets – Food-grade FKM for fatty food contact —

Temperature and Pressure Ratings

Maximum Service Temperature by Compound

Compound Type	Max Continuous Temp	Max Intermittent Temp
Standard Type A/B/C	400°F (204°C)	450°F (232°C)
Type GFLT	400°F (204°C)	450°F (232°C)
Type ETP	446°F (230°C)	500°F (260°C)
Peroxide-Cured	400°F (204°C)	450°F (232°C)

Pressure Ratings

FKM seals can handle: – Static seals: Up to 3,000 psi (207 bar) – Dynamic seals: Up to 1,500 psi (103 bar) – Low-pressure gas: Suitable for vacuum applications Note: Actual pressure ratings depend on seal geometry, temperature, and chemical environment. Always consult with your supplier for application-specific recommendations. —

FKM vs. Other Elastomers

Verdict: FKM is the top choice for: – High-temperature oil and fuel exposure – Chemical processing with aggressive media – Aerospace and defense applications – Long-term outdoor weathering requirements—Manufacturing ProcessesCompression Molding– Best for: Low to medium volume, large parts – Tolerance: ±0.005″ to ±0.020″ – Tooling Cost: $500-$5,000 – Per-part Cost: Moderate – Typical MOQ: 100-500 piecesInjection Molding– Best for: High volume, complex geometries – Tolerance: ±0.003″ to ±0.010″ – Tooling Cost: $5,000-$50,000 – Per-part Cost: Low at volume – Typical MOQ: 1,000-5,000 piecesTransfer Molding– Best for: Medium volume, insert molding – Tolerance: ±0.005″ to ±0.015″ – Tooling Cost: $2,000-$15,000 – Per-part Cost: Moderate – Typical MOQ: 500-2,000 piecesExtrusion– Best for: Continuous profiles, tubing – Tolerance: ±0.010″ to ±0.030″ – Tooling Cost: $1,000-$10,000 – Per-part Cost: Low – Typical MOQ: 500-2,000 meters—How to Select a FKM SupplierWhen sourcing FKM parts from China, due diligence is critical:1. Verify Material Authenticity– Request certificates of conformance (COC) – Ask for compound data sheets – Verify fluorine content via FTR (Fluorine Test Report) – Request CA (Certificate of Analysis) for each batch2. Check Manufacturing Capabilities– Do they have compression or injection molding? – What’s their typical lead time? – Can they handle custom formulations? – Do they offer secondary operations (skiving, bonding, etc.)?3. Quality Management– ISO 9001:2015 certification minimum – ISO 13485 for medical applications – IATF 16949 for automotive – Full inspection reports available?4. Testing Capabilities– Physical property testing (hardness, tensile, elongation) – Compression set testing – Volume swell testing (ASTM D471) – Low-temperature embrittlement testing5. Sample and Prototyping– Can they provide samples for validation? – Do they offer rapid prototyping? – What’s the sample lead time?Red Flags ⚠️– Prices too low (may indicate inferior materials) – No sample policy – Unable to provide test reports – Limited communication or response delays – No quality certifications—FKM Pricing and MOQPrice Factors1. Compound type (standard vs. specialty) 2. Order volume (economies of scale) 3. Part complexity (tooling requirements) 4. Tolerance requirements 5. Inspection requirementsTypical Pricing (USD per piece)

Property	FKM	Silicone	EPDM	NBR
Temp Range	-20 to +400°F	-85 to +450°F	-65 to +300°F	-40 to +250°F
Oil Resistance	Excellent	Poor	Poor	Good
Weather Resistance	Excellent	Excellent	Excellent	Fair
Steam Resistance	Poor	Good	Good	Poor
Acid Resistance	Good	Good	Good	Fair
Cost	$$$$	$$$	$$	$
FDA Compliant	Limited	Yes	Limited	No

Note: Prices vary significantly based on compound, volume, and specifications.MOQ Expectations– Standard O-rings: 100-500 pieces – Custom Molded Parts: 200-1,000 pieces – Extruded Profiles: 500-1,000 meters – Complex Assemblies: 50-500 pieces—FAQQ: Can FKM be used in steam applications?A: Standard FKM has poor steam resistance above 200°C. For steam applications, consider: – Type E FKM (steam-resistant grade) – Special peroxide-cured compounds – Or alternative materials like EPDM or PTFEQ: What’s the shelf life of FKM parts?A: Properly stored FKM parts typically last 10-20 years. Storage conditions: – Cool, dry environment (below 30°C) – Away from direct sunlight and ozone sources – No contact with solvents or chemicalsQ: Is FKM FDA compliant?A: Limited FDA compliance available. Standard FKM is not FDA-approved for food contact. For food-grade applications, request: – FDA 21 CFR 177.2600 compliant compounds – USP Class VI testing for medical devices – NSF/ANSI 51 certification for food equipmentQ: What’s the difference between Viton® and AFLAS®?A: Key differences:

Part Type	100 pcs	1,000 pcs	10,000 pcs
O-ring (10mm ID)	$0.50-1.00	$0.20-0.50	$0.10-0.30
Custom Gasket	$2.00-5.00	$1.00-2.50	$0.50-1.50
Complex Seal	$5.00-15.00	$3.00-8.00	$2.00-5.00

Property	Viton® (FKM)	AFLAS® (FEPM)
Fluorine Content	66-71%	57%
Steam Resistance	Poor	Excellent
Base Resistance	Poor	Excellent
Cost	Higher	Moderate

ApplicationsFuels, chemicalsSteam, amines

Q: Can FKM be bonded to metal?

A: Yes, with proper surface treatment: – Plasma treatment – Chemical etching – Primer coatings (like Chemlok) – Mechanical bonding (overmolding) —

Conclusion

FKM/Viton® rubber remains the premier choice for high-performance sealing applications requiring superior chemical and thermal resistance. From automotive fuel systems to aerospace hydraulics, FKM’s proven performance in extreme environments makes it the material of choice for critical applications. When sourcing FKM parts from China, partner with suppliers who can provide: – Validated compound data and test reports – Flexible manufacturing capabilities (compression, injection, extrusion) – Quality certifications (ISO 9001, IATF 16949, etc.) – Responsive technical support Ready to source FKM parts from a trusted China manufacturer? 👉 Get a Free Quote → Our team provides FKM compounds for aerospace, automotive, oil & gas, and chemical processing applications. Response within 24 hours with DFM feedback. — Related Guides: – The Complete Guide to Custom Rubber Gaskets – Material selection, manufacturing processes, and buyer guide – Silicone Rubber Parts: Properties and Applications – Medical, food-grade, and high-temp silicone solutions – NBR Rubber: Oil-Resistant Seals and Gaskets – Cost-effective nitrile solutions — This guide is for informational purposes. For specific application recommendations, consult with our engineering team.