Rubber & Elastomers•High-Temperature & Specialty Elastomers•

VERIFIED(Source-Verified)

Fluoroelastomer (FKM)

Primary Designation:ASTM FKM

Aliases:

Viton® (Registered Trademark of Chemours)FluoroelastomerFluorel® (Registered Trademark of 3M)FPM

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Omitted fields represent unverified properties. "Missing is better than invented."

Key Engineering Properties

Representative source rows, qualified by their reported conditions. Inspect the tables below for all values, limits, and source notes.

Service Temp Range

-15°C to 200°CContinuous Limit

Continuous service typically -15°C to +2...

Engineering Summary

Fluoroelastomer (FKM)—frequently identified by the commercial trade name Viton® (a registered trademark of The Chemours Company FC, LLC)—is a fluorinated hydrocarbon elastomer typically comprising copolymers of vinylidene fluoride (VDF) and hexafluoropropylene (HFP), or terpolymers with tetrafluoroethylene (TFE). The strength of the carbon-fluorine bond (approx. 485 kJ/mol) combined with steric shielding by bulky fluorine atoms imparts extraordinary chemical resistance to petroleum fuels, synthetic lubricants, hydraulic oils, and harsh chemicals alongside continuous thermal capability up to +200°C (+250°C intermittent). FKM has very low gas permeability and is self-extinguishing. Its limitations include poor flexibility at low temperatures (standard grades stiffen near -15°C) and incompatibility with low molecular weight ketones and esters.

Fluoroelastomer (FKM) Documented Applications

›Automotive engine crankshaft rear main oil seals, camshaft seals, and valve stem oil seals
›Fuel system injector O-rings, fuel pump seals, and flexible fuel tank quick-connect gaskets
›Chemical processing pump mechanical seal secondary O-rings, valve seats, and flue gas duct joints
›Aerospace turbine engine fuel system seals, hydraulic O-rings, and firewall barrier seals
›Oil and gas downhole wellbore tools, logging equipment seals, and subsea Christmas tree valves

Recognized Aliases

Source-backed commercial trade name and short designations cataloged in canonical data.

Viton® (Registered Trademark of Chemours)FluoroelastomerFluorel® (Registered Trademark of 3M)FPM

Elastomer Technical Profile • Fluoroelastomer (FKM)

ASTM D1418: FKMISO 1629: FPMASTM D2000: Type HK

Polymer backbone: Vinylidene fluoride-hexafluoropropylene copolymer / terpolymer. Thermoset and cast elastomer mechanical, thermal, and chemical behavior depends strongly on compounding ingredients, crosslink density, and curing system.

Key Engineering Advantages

•Superior continuous high-temperature resistance up to 200°C (392°F) with intermittent capability to 250°C
•Outstanding resistance to aggressive automotive fuels, transmission fluids, and synthetic motor oils
•Exceptional resistance to chemical solvents, aromatic hydrocarbons, and concentrated mineral acids
•High elevated-temperature compression set retention in continuous high-heat service
•Extremely low fuel and gas permeation rates; self-extinguishing in open flame

Engineering Limitations & Risks

•Poor low-temperature flexibility in standard bisphenol grades (dynamic sealing limit approx -15°C)
•Severely attacked by low molecular weight ketones (acetone, MEK), esters (ethyl acetate), and amines
•Incompatible with hot anhydrous ammonia and strong concentrated caustic solutions
•Significantly higher raw material and finished component cost than hydrocarbon elastomers

Thermal Operating Limits & Service Profile

Min Continuous-15°C

Max Continuous200°C

Max Intermittent / PeakNot specified

Note: Continuous service typically -15°C to +200°C (-5°F to +392°F) for standard bisphenol-cured compounds per Parker ORD 5700 Section II (Figure 2-3 & Table 2-2). Excursions above 200°C accelerate compression set and thermal-oxidative aging, substantially shortening service life. ASTM D2000 Type HK callouts specify 70h accelerated test requirements at 250°C for automotive material classification rather than continuous service ratings.

Chemical & Environmental Media Compatibility (Engineering Selection Guide)

Parker ORD 5700 Selection Ratings

Ratings represent manufacturer engineering fluid selection guidance (Parker ORD 5700 / producer design manuals). They do not substitute for batch-specific ASTM D471 / ISO 1817 laboratory immersion testing under service temperature, pressure, and dynamic stress.

Petroleum Hydrocarbons & Synthetic OilsMinimal swell in ASTM Reference Oils IRM 901, 902, 903 and synthetic polyol esters

EXCELLENT

Automotive Gasoline & Diesel FuelsSuperior resistance to high-aromatic gasoline, ethanol blends (E10, E85), and biodiesel

EXCELLENT

Concentrated Mineral AcidsResistant to hydrochloric, sulfuric, and hydrofluoric acids

EXCELLENT

Atmospheric Ozone & WeatheringOutstanding resistance to atmospheric ozone, UV degradation, and fungal growth (exhibits zero cracking after 100 pphm ozone exposure per ASTM D1149)

EXCELLENT

Ketones (Acetone, MEK)Rapid severe swelling and chemical degradation

NOT RECOMMENDED

Amines & Hot AmmoniaStandard bisphenol-cured grades undergo dehydrofluorination; use base-resistant FKM (AFLAS or peroxide FKM)

POOR

Compounding & Physical Property Context

Compounding Dependency: FKM polymers fall into 5 distinct classes (ASTM D1418 Types 1 through 5): Type 1 (copolymer VDF/HFP, 66% F) is general purpose; Type 2 (terpolymer VDF/HFP/TFE, 68–70% F) offers lower fluid swell; Type 3 (GLT, PMVE-bearing) provides -40°C flexibility; Type 4 (base-resistant) withstands amines; Type 5 withstands aggressive engine coolants. Bisphenol cure gives best compression set; peroxide cure gives best acid and steam resistance.

Gas & Fluid Permeability: Extremely low gas and fuel permeation; benchmark standard for CARB and EPA automotive evaporative emission barrier compliance.

Abrasion Endurance: Good abrasion resistance for static and moderate-speed rotary seals; inferior to polyurethane in dynamic particulate slurry environments.

Tear Resistance: Adequate ASTM D624 Die C tear strength for precision O-rings and gaskets. (Not directly comparable to trouser tear Die T).

Compression Set (ASTM D395): High elevated-temperature compression set resistance among commercial sealing elastomers per Parker ORD 5700 Section II.

Fluoroelastomer (FKM) Specifications & Designations

Standard Designations & Applicable Specifications — Semantically classified designations distinguishing primary standard identifiers, commercial trade names, and applicable specification references.

Direct Standard DesignationsDIRECT DESIGNATION

3 Primary Identifiers

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System	Identifier	Standard System Name	Classification Notes & Provenance
ASTMPRIMARY	FKM	ASTM D1418 Nomenclature	—Ref: Standard Practice for Rubber and Rubber Latices—Nomenclature (ASTM D1418-22) / Rubber and latices—Nomenclature (ISO 1629:2013)
ISO	FPM	ISO 1629 Nomenclature	Designated as FPM in ISO 1629:2013 Clause 3.3.4 (rubbers having fluoro, fluoroalkyl or fluoroalkoxy substituent groups on the polymer chain); corresponding ASTM D1418 designation is FKM.Ref: Standard Practice for Rubber and Rubber Latices—Nomenclature (ASTM D1418-22) / Rubber and latices—Nomenclature (ISO 1629:2013)
ASTM-D2000	Type HK	ASTM D2000 Classification System	Classified under ASTM D2000 as Type HK (defined by 70h accelerated heat-aging test at 250°C with volume change under 10% in ASTM IRM 903 oil; accelerated test temperatures serve automotive classification and do not represent continuous service ratings).Ref: Standard Classification System for Rubber Products in Automotive Applications (ASTM D2000-21 / SAE J200:2021)

Recognized Commercial Aliases & Trade NamesCOMMON ALIAS

4 Listed

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Recognized Name / Alias	Classification	Technical Usage & Context
Viton® (Registered Trademark of Chemours)	Commercial Alias	Colloquial or commercial industry synonym
Fluoroelastomer	Colloquial Alias	Colloquial or commercial industry synonym
Fluorel® (Registered Trademark of 3M)	Commercial Alias	Colloquial or commercial industry synonym
FPM	Spelling_variant Alias	Colloquial or commercial industry synonym

Applicable Specifications & Product Form ReferencesSPECIFICATION REFERENCE

3 Applicable Standards

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Standards Body	Specification Code	Specification Title / Scope	Relationship Type
ASTM International	ASTM D1418	Standard Practice for Rubber and Rubber Latices—NomenclatureSTANDARD · Edition: ASTM D1418-22	Specification Reference
ISO	ISO 1629	Rubber and latices — NomenclatureSTANDARD · Edition: ISO 1629:2013	Specification Reference
ASTM International	ASTM D2000	Standard Classification System for Rubber Products in Automotive ApplicationsSTANDARD · Edition: ASTM D2000-21	Specification Reference

Engineering Notice: Applicable specifications establish manufacturing requirements, dimensional tolerances, and test criteria for specific product forms (e.g. bus bar, wire, plate, pipe). They represent applicable technical standards, not alternative or equivalent alloy grades.

Fluoroelastomer (FKM) Processing & Fabrication

Machining, joining, forming, and thermal processing ratings cataloged from the cited authoritative technical reference.

Source: Parker Hannifin Corporation, Engineered Materials Group

Machinability

Cryogenically deflashed with liquid nitrogen; turned on CNC lathes equipped with diamond-sharp carbide cutters.

Heat Treatment & Working Ranges

Bisphenol cure (standard Type 1) or peroxide cure (for aggressive sour gas/acid resistance). Mandatory oven post-cure at 230°C for 16 to 24 hours to complete crosslinking and achieve minimum compression set.

Forming & Cold Working

Milled on cool water-chilled roll mills; compounded with mineral fillers and basic metal oxides (Ca(OH)₂ and MgO) as acid acceptors. Compression, transfer, and injection molded; extruded into chemical tubing.

Fluoroelastomer (FKM) Equivalent & Comparable Grades

Comparable Grades & Cross-References: Carefully classified cross-reference relationships for Fluoroelastomer (FKM). Comparable does not mean equivalent.

Scroll horizontally for relationship classifications & comparisons

Related Material	Family	Relationship Classification	Metallurgical Notes & Differences	Status	Action
Nitrile Butadiene Rubber (NBR)	rubber-and-elastomers	Commonly Compared	FKM provides superior high-temperature capability (+200°C vs +100°C) and broader fuel resistance; NBR offers lower cost and better low-temperature flexibility (-30°C vs -15°C).Materials serve different design priorities (e.g. higher strength vs superior corrosion resistance or cost).	VERIFIED	Side-by-Side Compare →
Hydrogenated Nitrile Rubber (HNBR)	rubber-and-elastomers	Commonly Compared	FKM resists higher temperatures and aggressive synthetic engine oils; HNBR provides superior mechanical tensile strength, dynamic cut-growth resistance, and better low-temperature behavior.Materials serve different design priorities (e.g. higher strength vs superior corrosion resistance or cost).	VERIFIED	Side-by-Side Compare →
Silicone Rubber (VMQ)	rubber-and-elastomers	Commonly Compared	VMQ offers superior low-temperature performance down to -60°C; FKM provides unmatched resistance to fuels, petroleum oils, and chemical solvents where VMQ swells and dissolves.Materials serve different design priorities (e.g. higher strength vs superior corrosion resistance or cost).	VERIFIED	Side-by-Side Compare →

Related Engineering & Metallurgy Guides

Contextual technical guides explaining degradation mechanisms, testing methodologies, and selection criteria relevant to Fluoroelastomer (FKM).

Material Selection18 min read

Types of Rubber: Elastomer Classification, Chemical Resistance & Selection Guide

Selecting the correct rubber is not a matter of choosing a generic flexible polymer—it requires matching molecular backbone chemistry to service temperature, chemical media polarity, dynamic fatigue, and compression set. This engineering guide classifies the 11 primary elastomer families, detailing their ASTM D1418 / ISO 1629 designations, mechanical performance envelopes, and rigorous selection algorithms.

Author: MatGrades Materials Engineering GroupRead Guide →

Sources

Sources & Provenance Trail: Authoritative reference publications, standards specifications, and data registers cited across this material record.

ASTM International, ISO & Elastomer Engineering Technical CommitteesStandard Practice for Rubber and Rubber Latices—Nomenclature (ASTM D1418-22) / Rubber and latices—Nomenclature (ISO 1629:2013)

STANDARDS ORG

Authoritative international nomenclature defining rubber acronyms and classification families.

Issuing Body: ASTM International & ISO Technical Committee ISO/TC 45 (Rubber and Rubber Products)Revision: ASTM D1418-22 / ISO 1629:2013View Source Record ↗

ASTM International, ISO & Elastomer Engineering Technical CommitteesStandard Classification System for Rubber Products in Automotive Applications (ASTM D2000-21 / SAE J200:2021)

STANDARDS ORG

Standardized classification system establishing Type and Class designations and line callouts for vulcanized rubber compounds.

Issuing Body: ASTM International & SAE International Technical CommitteesRevision: ASTM D2000-21View Source Record ↗

ASTM International, ISO & Elastomer Engineering Technical CommitteesParker O-Ring Handbook (Catalog ORD 5700) & Elastomer Engineering Selection Guide

Development BenchmarkSTANDARDS ORG

Global engineering seal benchmark establishing continuous operating temperature envelopes (Figure 2-3), elastomer property comparisons (Table 2-2), ASTM D395 Method B compression set benchmarks, and manufacturer engineering fluid compatibility selection ratings (distinguished from raw laboratory immersion coupons).

Issuing Body: Parker Hannifin Corporation, Engineered Materials GroupRevision: ORD 5700 (2018/2023)View Source Record ↗

Intellectual Property & Provenance Notice: Mat Grades cites technical literature from recognized industry associations and standards organizations. Underlying technical standards and publication data remain the intellectual property of their respective issuing organizations.