Guide

FVMQ Explained: Fluorosilicone Temperature Range, Properties, and Aerospace Applications

FVMQ handles jet fuel and cold soak from -60°C to 200°C / 392°F longterm, but low tear strength limits it to static seals. See what replaces it.

Updated September 29, 2026 · 19 min read · 14 chapters

Key Points

What's in this guide

  1. 1 FVMQ Chemistry: A Siloxane Backbone Carrying Fluorine
  2. 2 The Property Envelope Engineers Should Expect
  3. 3 200°C / 392°F Is the Upper Thermal Limit
  4. 4 Low Temperature Flexibility Is FVMQ's Strongest Card
  5. 5 Fluid Resistance Beats Silicone and Trails FKM
  6. 6 Mechanical Strength Is the Constraint Most Teams Underestimate
  7. 7 Low-Volatile FVMQ Answers Silicone's Contamination Reputation
  8. 8 Specifications That Govern FVMQ in Aerospace
  9. 9 Where FVMQ Earns the Specification
  10. 10 FVMQ Coatings, Sealants, and Adhesives Extend the Chemistry Beyond Seals
  11. 11 Four Boundaries FVMQ Cannot Cross
  12. 12 What Engineers Reach for Next
  13. 13 Custom Formulation Covers FVMQ, FKM, and FFKM
  14. 14 Match the Chemistry to the Requirement

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FVMQ, or fluorosilicone, is a siloxane elastomer modified with a trifluoropropyl side group that adds jet fuel and oil resistance to standard silicone's cold flexibility. It seals against jet fuel at temperatures that turn standard FKM stiff, and it swells far less in fuel than standard VMQ silicone.

FVMQ owns a narrow niche with hard edges. Engineers who know exactly where the envelope ends specify it well, and engineers who stretch it past those edges end up pulling hardened, torn, or swollen parts.

Everything below is that envelope in detail, including the materials that take over when a program runs past it.

Chapter 1 FVMQ Chemistry: A Siloxane Backbone Carrying Fluorine

FVMQ is poly(methyl-3,3,3-trifluoropropyl siloxane) with a small vinyl content for cure. ASTM D1418 designates it FVMQ, and drawings usually call it out as Type F, Class K under ASTM D2000.

The backbone stays siloxane. A trifluoropropyl group replaces one methyl group per repeat unit, and that substitution drives the major property differences between FVMQ and standard VMQ silicone.

The Backbone Sets the Temperature Envelope

The Si-O backbone combines high bond energy with a low barrier to chain rotation. The low rotational barrier keeps the polymer flexible at cold-soak temperatures, and the bond energy keeps it stable well past the point where hydrocarbon elastomers oxidize.

Fluorine Sets the Fluid Behavior

Pendant CF₃ groups shift the polymer's solubility parameter away from aliphatic hydrocarbons. Swell in Jet A, JP-8, and hydrocarbon hydraulic fluids drops from unusable in VMQ to acceptable in FVMQ.

The Backbone Also Explains the Failures

Siloxane chains have weak intermolecular forces. That shows up as low tensile strength, low tear energy, and gas permeability substantially higher than fluorocarbon elastomers.

Reinforcing silica narrows the mechanical gap with FKM. It never closes it, and every FVMQ application decision follows from that trade.

FVMQ, VMQ, and PVMQ Are Not Interchangeable

ASTM D1418 separates three silicone families that often get grouped together on drawings. VMQ carries methyl and vinyl groups, PVMQ adds phenyl groups for better low temperature performance, and FVMQ adds the trifluoropropyl group for fuel resistance.

Only FVMQ is built for hydrocarbon fuel contact. A drawing that calls out "silicone" for a fuel-wetted seal invites a substitution that will swell in service, so the designation belongs on the drawing in full.

Chapter 2 The Property Envelope Engineers Should Expect

Published FVMQ property ranges vary by compounder, durometer, and filler loading. The table below covers what aerospace-grade compounds typically deliver, with the governing test method for each value.

PropertyTest methodTypical FVMQ range
HardnessASTM D224040–80 Shore A
Tensile strengthASTM D4126.9–10.3 MPa (1,000–1,500 psi)
Elongation at breakASTM D412150–400%
Compression setASTM D395 Method BModerate; generally higher than FKM at equal durometer
Low temperature brittlenessASTM D2137-68°C to -60°C / -90°F to -76°F
TR-10 retractionASTM D1329-60°C to -55°C / -76°F to -67°F
Longterm service temperatureCompound dependent; verify per ASTM D573175°C to 200°C / 347°F to 392°F
Intermittent peak exposureCompound dependentUp to 230°C / 446°F
Tear resistanceASTM D624Low
Gas permeabilityASTM D1434High
Abrasion resistanceASTM D5963Poor
Outgassing (TML / CVCM)ASTM E595Grade and process dependent

Read the table as a shape. FVMQ trades mechanical strength for thermal range and buys back partial fuel resistance with fluorine.

Verify every value against the specific compound datasheet before it goes on a drawing. Two compounds sold under the same generic name can differ widely in tensile strength, compression set, and low temperature performance.

Chapter 3 200°C / 392°F Is the Upper Thermal Limit

FVMQ suppliers quote up to 200°C / 392°F longterm and 230°C / 446°F intermittent. Many compounds carry lower longterm ratings, often near 175°C / 347°F, so the compound datasheet governs.

The longterm figure is the one that matters, and heat aging per ASTM D573 shows why. As temperature climbs toward and past the rating, oxidative crosslinking hardens the compound in air, while confined, low-oxygen seals can revert and soften instead.

Either way, elongation collapses and sealing force decays. Service life shortens rapidly as temperature rises, so a seal run at its rated limit carries far less margin than one run well below it.

Compression Set Is the Early Warning

Compression set shows heat damage before anything else does. An O-ring that has lost recovery can look intact on removal and still fail to seal through the next thermal cycle.

Specify compression set limits at the actual service temperature, not only at a standard test condition. That single requirement catches most thermally marginal compounds before they reach the aircraft.

Post-Cure Sets the Starting Point

Most FVMQ compounds need an oven post-cure to reach their rated compression set and heat resistance. A part that skips or shortens post-cure starts service with less margin than the datasheet suggests.

Call out post-cure on the drawing or in the purchase specification when the compound datasheet requires it. Receiving inspection should confirm hardness and compression set on the delivered lot.

Post-cure also drives off residual volatiles. Parts bound for contamination-sensitive assemblies can take a further vacuum bake-out, covered in the contamination section below.

Steam Is a Separate Failure Mode

FVMQ also degrades in pressurized steam. Siloxane hydrolysis attacks the backbone directly, so steam service is a poor fit even when the temperature sits inside the rating.

Chapter 4 Low Temperature Flexibility Is FVMQ's Strongest Card

This is where FVMQ beats standard FKM outright. Standard FKM copolymer carries a glass transition near -18°C / 0°F and a practical static service floor around -26°C / -15°F.

Low temperature FKM grades reach roughly -40°C / -40°F. FVMQ stays functional near -60°C / -76°F, with brittle points approaching -68°C / -90°F per ASTM D2137.

That spread is the reason fluorosilicone holds a place in aircraft fuel systems. A seal in a wing tank or an under-wing fuel line sees cold soak at cruise altitude and fuel contact at the same time.

FKM handles the fuel and stiffens in the cold. VMQ silicone handles the cold and swells in the fuel. FVMQ handles both adequately, which is exactly what the application needs.

TR-10 Is the Design Number for Sealing

The brittle point tells an engineer where the compound shatters under impact. It says little about whether a seal still tracks a moving gland face at that temperature.

TR-10 retraction per ASTM D1329 is the more useful design number. A seal operating below its TR-10 temperature recovers slowly, and slow recovery during a rapid cool-down is where cold-soak leaks start.

Cold soak rarely arrives alone. Fuel system seals cycle between cold cruise and warm ground operation many times a day, so the compound must recover through the full range on every flight rather than survive a single cold exposure.

Chapter 5 Fluid Resistance Beats Silicone and Trails FKM

Fluid compatibility is where specification arguments happen, so the comparison below is qualitative by design. Volume swell per ASTM D471 depends on immersion temperature, duration, and compound, and a single percentage figure misleads more often than it informs.

FluidVMQ siliconeFVMQFKM
Jet A / JP-8Poor, heavy swellGoodExcellent
Synthetic hydrocarbon hydraulic fluid (MIL-PRF-83282)PoorGoodExcellent
Phosphate ester hydraulic fluidPoor to fairPoor to fairPoor
Synthetic ester engine oil (MIL-PRF-23699)PoorGoodGood
Ketones and low molecular weight estersPoorPoorPoor, standard copolymer
SteamPoorPoorPoor to fair, grade dependent
Glycol de-icing fluidGoodGoodGood

Two entries deserve attention. Neither FVMQ nor standard FKM copolymer is a good choice for phosphate ester hydraulic fluid, and EPDM is the usual answer there.

FVMQ also fails in ketones and in steam. A cleaning or steam-wash process can destroy a seal that survived every operational fluid on the aircraft, so maintenance procedures belong in the fluid review.

Outside the fluid system, FVMQ keeps the weathering and ozone resistance of the silicone family. Exposed seals and coatings do not crack from ozone the way many hydrocarbon elastomers do.

Fuel Chemistry Changes the Answer

Jet fuel is not a single fluid. Aromatic content varies by source and blend, and swell behavior in any elastomer shifts with it.

Sustainable aviation fuel blends add another variable, because their aromatic content can differ from conventional Jet A. Qualification fluids should match the fuels the aircraft will actually burn, including any blends the operator plans to adopt.

Chapter 6 Mechanical Strength Is the Constraint Most Teams Underestimate

Fluorosilicone is a weak elastomer. Tensile strength sits well below FKM at equal durometer, tear energy per ASTM D624 is low, and abrasion resistance is poor.

Those three properties set the same boundary from different directions. FVMQ works in static seals and struggles in dynamic ones.

Dynamic Service and Extrusion

Rod seals, rotary shaft seals, and anything with reciprocating contact wear through fluorosilicone quickly. High pressure adds extrusion and nibbling, because the compound lacks the modulus to resist gap extrusion without backup rings.

Permeability

The siloxane backbone passes gases and fuel vapor at rates well above fluorocarbon elastomers. That matters for vapor containment, emissions, and any closed volume where permeation drives pressure change or contamination.

Design Practices That Extend FVMQ Seal Life

Good gland design recovers much of the margin that the compound gives away. These practices matter more for FVMQ than for stronger elastomers.

Specify backup rings wherever pressure and clearance gaps create any extrusion risk. Hold squeeze within the seal manufacturer's recommended range, because excess compression accelerates compression set at temperature.

Leave gland fill margin for thermal expansion and fuel swell so the seal never fills the groove solid. Lubricate on assembly and protect the seal from sharp edges and threads, since low tear strength turns small nicks into leak paths.

Chapter 7 Low-Volatile FVMQ Answers Silicone's Contamination Reputation

Silicone earned a bad name with contamination engineers for good reason. Early compounds carried residual low-molecular-weight siloxanes that migrated out of the part and redeposited on nearby surfaces.

A thin siloxane film on a bonding surface causes coating and adhesive bond failures. On optics it fogs lenses and sensor windows, and on electrical contacts it leaves an insulating layer.

Process Controls Remove the Volatiles

Compounders now formulate and process high-performance FVMQ elastomers, seals, and coatings to minimize those residual siloxanes and other volatile or extractable constituents. Controlled compounding, post-curing, cleaning, and vacuum bake-out where required all reduce what the finished part can release.

The result is substantially lower contamination and outgassing with the same low temperature flexibility and fuel resistance. Those gains depend on the grade and on how the part was processed, which is why the data matters more than the designation.

Measure It Rather Than Assume It

ASTM E595 is the standard screen for outgassing in vacuum. It reports total mass loss (TML) and collected volatile condensable materials (CVCM), and many programs screen against limits of 1.0% TML and 0.10% CVCM.

Extractables testing covers what outgassing screens miss, including residues that transfer by contact rather than vapor. For contamination-sensitive applications, confirm performance with material-specific outgassing and extractables data rather than assuming it from the FVMQ designation alone.

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Chapter 8 Specifications That Govern FVMQ in Aerospace

Fluorosilicone carries a mature specification stack, which is part of why it persists despite its limits. Program teams evaluating FVMQ will encounter the following documents.

  • AMS-R-25988 and MIL-DTL-25988: The governing aerospace specifications for fluorosilicone rubber, both descended from MIL-R-25988 and organized by type, class, and durometer grade.
  • SAE AMS 3325, AMS 3327, and AMS 3328: Fuel- and oil-resistant fluorosilicone specifications separated by hardness range, covering sheet, strip, extrusions, and molded shapes. AMS 3325 supersedes AMS 3326.
  • ASTM D2000 Type F, Class K: The common line callout for FVMQ, pairing a 200°C / 392°F heat-aging test temperature with a 10% maximum volume swell limit in IRM 903 oil.
  • ASTM D1418: The nomenclature standard that fixes FVMQ as the correct designation, separating it from VMQ and PVMQ silicones.

Durometer Selection Follows the Joint

Hardness choice follows the same logic as any elastomer seal. Softer grades suit low-closure-force gaskets and irregular mating surfaces, while harder grades resist extrusion in higher-pressure O-ring glands.

FVMQ's low tear strength shifts that choice slightly upward in pressure service. A harder grade with backup rings usually outlasts a softer grade that relies on the gland alone.

Cost Shapes the Decision Too

Cost sits outside the specification stack and still drives decisions. Fluorosilicone compounds often cost more per kilogram than both VMQ and standard FKM, so programs frequently switch to one or the other rather than absorb the difference.

Chapter 9 Where FVMQ Earns the Specification

FVMQ wins when an application demands two properties that no other single elastomer combines at moderate temperature. Specify it when these conditions hold at the same time.

  • Cold soak plus fuel contact: A service floor below -40°C / -40°F with ongoing exposure to Jet A, JP-8, or hydrocarbon hydraulic fluid.
  • Static geometry: O-rings, gaskets, face seals, and coated surfaces with no reciprocating, rotary, or abrasive contact.
  • Moderate heat: Longterm temperature at or under the compound's rating, 200°C / 392°F at most, with intermittent excursions that stay under 230°C / 446°F.

That niche is real, and it is narrow. Engineers regularly stretch FVMQ past its edges because the fluorosilicone datasheet is the closest thing on the shelf.

When VMQ or FKM Is the Better Buy

FVMQ is the wrong choice when only one of its two strengths is needed. A dry, cold application with no fuel contact is usually better served by VMQ or PVMQ silicone at lower cost.

A fuel-wetted seal that never drops below the FKM service floor belongs in FKM. The fluorosilicone premium buys nothing there, and FKM adds tensile strength, tear resistance, and lower permeability.

Typical Aircraft Fuel System Applications

Most aerospace FVMQ sits in and around the fuel system, where cold soak and fuel contact meet. Common applications include fuel tank access panel seals, fuel line connector O-rings, fuel quantity probe seals, and refuel and vent system seals.

Each of these sees fuel on one side and outside-air temperature on the other. None of them sees sliding contact, which keeps them inside the envelope where fluorosilicone performs.

Chapter 10 FVMQ Coatings, Sealants, and Adhesives Extend the Chemistry Beyond Seals

Engineers usually specify FVMQ as a molded or extruded part, and the chemistry also works as a coating, sealant, or adhesive. A solvent system carries uncured fluorosilicone, which sprays or dips as a thin film and cures in place.

That opens applications a molded part can't reach. Complex shapes, fabrics, electronics, and existing components pick up fluorosilicone's fuel and cold resistance without tooling for a new part.

What Carries Over From the Molded Form

A cured fluorosilicone film keeps the chemistry of a molded part. It holds the same low temperature flexibility, the same hydrocarbon fuel resistance, and the same 200°C / 392°F upper limit.

Thin-film geometry changes how the weak points show up. Abrasion and erosion remove a coating faster than they damage a thick seal, and permeation reaches the substrate across a much shorter path.

Surface Preparation Decides Coating Life

Siloxane polymers bond poorly to most substrates on their own. A fluorosilicone coating lives or dies on surface preparation and on a primer system matched to the substrate, whether that substrate is aluminum, composite, or an existing elastomer part.

That makes adhesion a formulation problem as much as an application problem. Specify primer selection, cure schedule, and film build together as one system, and re-evaluate the coating whenever any one of them changes.

Application method adds a contamination question of its own. Overspray and airborne siloxanes in a shop can reach nearby surfaces awaiting coating or bonding, so FVMQ work needs the same masking and area separation discipline as any silicone process.

Sealants and Adhesives Carry the Same Chemistry

Fluorosilicone sealants fill fillets, seams, and fastener heads where a molded seal cannot reach. Fluorosilicone adhesives bond FVMQ parts to each other and to substrates in joints that see fuel and cold soak.

Both forms follow the same envelope as the molded compound. Cure schedule, bond line or bead geometry, and substrate preparation decide how much of that envelope a given joint delivers.

Where Sprayed FVMQ Fits

The best coating applications match the molded envelope: cold, fuel exposure, moderate heat, and low mechanical wear. These application classes fit that profile.

  • Seal and gasket overcoats: A thin fluorosilicone skin on a VMQ silicone part adds fuel and oil resistance on the wetted face while the silicone core keeps its sealing properties.
  • Coated fabrics and diaphragms: Fabric-reinforced fluorosilicone diaphragms already run in fuel regulators and fuel controls, and coating extends the approach to custom diaphragms, flexible boots, and fuel-resistant covers.
  • Fuel system electronics and sensors: Probes, pump electronics, and connectors that see fuel vapor and cold soak benefit from a flexible dielectric film that tolerates thermal cycling. Low-volatile grades suit assemblies near optics and electrical contacts.
  • Fuel tank fillets and fastener overcoats: Fluorosilicone sealant chemistry serves fuel tank areas that run hotter than polysulfide sealants tolerate.
  • Cold-region equipment: Ground support equipment, refueling hardware, and arctic energy instrumentation combine hydrocarbon exposure with extreme cold.

What a Fluorosilicone Film Can't Do

A sprayed film inherits every limit of the molded compound, and thin-film geometry sharpens some of them. Rule out FVMQ coatings for these conditions.

  • Longterm heat above 200°C / 392°F: The film hardens or reverts on the same timeline as a molded part, with less material to absorb the damage.
  • Erosion and abrasion: Rain, sand, airflow, and handling wear away a low-tear film quickly, which rules out leading edges and high-traffic surfaces.
  • Certain cleaning solvents and steam: Some solvent wipes common in surface prep and maintenance swell a cured fluorosilicone film. Confirm the cleaning process with the GREOS technical team before specifying.
  • Primary moisture barrier: Siloxane permeability makes a thin film a weak barrier against moisture and vapor reaching the substrate.

Chapter 11 Four Boundaries FVMQ Cannot Cross

Most FVMQ misapplications trace back to one of four boundaries, whether the FVMQ is a molded seal, a coating, a sealant, or an adhesive. None of them is a problem a better compounder can formulate away.

  • Sustained temperature above the compound's rating: Hardening or reversion and compression set decay, with service life shortening rapidly as temperature climbs.
  • Dynamic and abrasive contact: Low tear energy and poor abrasion resistance take seals and coatings apart mechanically.
  • Permeation-sensitive volumes: The siloxane backbone passes gas and vapor at rates FKM does not.
  • Steam and aggressive solvents: Hydrolysis and solvent swell attack the polymer regardless of how well it handles fuel.

When a requirement crosses one of these lines, the answer is a different chemistry, mapped below.

Catching the boundary early saves the most money. A material review at the design stage costs far less than a seal or coating change after qualification testing has started.

Chapter 12 What Engineers Reach for Next

The right replacement depends on which boundary the requirement crossed. The table below maps each common gap to the material class that usually closes it.

RequirementMaterial class to evaluateWhy it fits
Longterm heat above 200°C / 392°FFKM seal compound or FKM coatingHigher thermal stability and broader chemical resistance
Phosphate ester hydraulic fluidEPDMIndustry-standard phosphate ester resistance with good low temperature flexibility
Dynamic, abrasive, or high-pressure serviceFKM seal compound with backup ringsHigher tensile strength, tear resistance, and extrusion resistance
Low permeationFKMLower gas and vapor permeability than siloxane elastomers
Extreme heat and chemical exposureFFKMHighest thermal and chemical resistance in the fluoroelastomer family
Cold soak below -40°C / -40°F with fuel contactStay with FVMQNo other single elastomer matches this combination

FKM Takes Over Above 200°C / 392°F

FKM fluoroelastomer chemistry handles the heat and chemical exposure that end FVMQ's service life. For seals, that means an FKM compound, and for surfaces, it means an FKM coating.

GREOS ENDURE FKM coating carries a 250°C / 480°F longterm thermal rating and maintains elastomeric flexibility through thermal cycling and structural vibration. It applies with standard spray equipment using a solvent system designed to meet CARB requirements. No special equipment. No process changes.

The trade is cold performance. FKM stiffens well above FVMQ's service floor, so programs that need both deep cold soak and high heat should scope the requirement with an application engineer before choosing either chemistry.

EPDM Owns Phosphate Ester Service

Phosphate ester hydraulic systems are the one place where neither fluorinated elastomer belongs. EPDM resists these fluids and stays flexible at low temperature, which is why it dominates phosphate ester seal applications.

The catch is petroleum. EPDM swells badly in fuels and mineral oils, so any seal that could see both fluid families needs a careful review of which exposure dominates.

Dynamic Seals Move to FKM

Reciprocating and rotary seals need tear strength and abrasion resistance that fluorosilicone cannot supply. FKM seal compounds, paired with backup rings in high-pressure glands, cover most fuel-wetted dynamic service.

Where the dynamic seal also sees deep cold soak, low temperature FKM grades narrow the gap. Programs that need both properties at the edges of each envelope should test candidate compounds at the actual temperature extremes.

How Surface Options Compare

Fluorosilicone and FKM coatings compete with the surface protection options engineers already know. The comparison below places them side by side.

Surface optionUpper temperature limitFlexibilityFluid resistanceApplication method
FVMQ coating200°C / 392°FElastomericGood in fuels and oilsSpray or dip, custom formulated
Polyurethane topcoat177°C / 350°FFlexibleGood at ambient temperatureStandard spray
Silicone coating315°C / 600°FRigid, cracks under vibrationPoorStandard spray
Ceramic barrier538°C / 1000°F and aboveNoneGoodSpecialist process
GREOS ENDURE FKM coating250°C / 480°F longtermElastomericExcellent flight line fluids resistanceStandard spray

Higher Tiers Are Coming

Programs running hotter than 250°C / 480°F have two more tiers coming in the GREOS three-tier product architecture. GREOS VANGUARD (coming soon), an FKM+ ceramic hybrid, carries a 325°C / 600°F longterm rating for defense rotorcraft and fighter platforms.

GREOS APEX (coming soon), an FFKM perfluoroelastomer, carries a 350°C / 660°F longterm rating for hypersonic and directed-energy environments.

Chapter 13 Custom Formulation Covers FVMQ, FKM, and FFKM

Standard products cover standard requirements. When a program's temperature, fluid exposure, substrate, or finish falls between catalog options, GREOS formulates to the requirement.

That work spans fluorosilicone, FKM, and FFKM chemistry. A cold-soak fuel system surface and a 250°C / 480°F nacelle surface get different chemistries from the same formulation team.

Fluorosilicone coatings benefit most from that approach. Few catalog products exist for sprayed FVMQ, so matching the film to a specific substrate, fuel, and cold-soak profile usually means formulating for it.

Two Paths to a Program Coating

GREOS formulation work starts one of two ways: from an existing chemistry, or from a requirement nothing on the market meets. Both paths lead to a coating built for the program.

A modified standard starts from an existing GREOS chemistry and tunes it for temperature target, fluid exposure, outgassing performance, color and finish, cure schedule, or substrate. It usually reaches evaluation samples faster than new development.

Custom development builds a new fluorosilicone, FKM, or FFKM coating from the ground up. GREOS selects pigments, fillers, and solvent systems for the program's thermal, chemical, and regulatory constraints.

A Defined Path From Requirement to Coating

Every program follows four steps, scoped up front so development never runs open-ended. Customers conduct their own qualification testing on evaluation samples.

  • Scope: Define the requirement and success criteria together in a short statement of work.
  • Formulate: Modify a standard chemistry or develop a new system, using solvent systems designed to meet CARB requirements.
  • Evaluate: Engineer the coating to meet the relevant ASTM, RTCA DO-160G, and MIL-STD test methods, then supply evaluation samples for customer testing.
  • Deliver: Supply the coating, a technical datasheet, and application guidance for production.

What to Send an Application Engineer

A useful formulation conversation starts with six inputs: the temperature profile, the fluid exposure, the substrate, the finish, any outgassing or cleanliness requirements, and the timeline. Having them ready shortens scoping.

For temperature, include longterm, intermittent peak, and cold-soak values. For fluids, list cleaning and maintenance chemicals alongside operational fluids, and note any existing primer on the substrate.

Chapter 14 Match the Chemistry to the Requirement

Fluorosilicone answers a specific question well: how to seal or protect a surface that sees jet fuel at -60°C / -76°F without exceeding 200°C / 392°F. Outside that envelope, FKM and FFKM take over.

GREOS formulates across all three chemistries. Request the technical datasheet for GREOS ENDURE, or contact an application engineer with your thermal, fluid exposure, and substrate requirements to start a formulation conversation.

Performance characteristics and temperature ratings are based on internal laboratory testing. Actual results may vary by application, substrate, and operating conditions. Customers should conduct their own testing to confirm suitability for their specific use cases. Information provided is for reference only and does not constitute a warranty or performance guarantee. For application-specific guidance, contact the GREOS technical team.

Performance Disclaimer

Performance characteristics and temperature ratings are based on internal laboratory testing. Actual results may vary by application, substrate, and operating conditions. Customers should conduct their own testing to confirm suitability for their specific use cases. Information provided is for reference only and does not constitute a warranty or performance guarantee. For application-specific guidance, contact the GREOS technical team.

Frequently Asked Questions About FVMQ

Engineers evaluating fluorosilicone tend to circle back to the same set of questions before they specify it. The answers below stand on their own for quick reference.

What does FVMQ stand for?

FVMQ stands for fluorovinylmethylsiloxane, commonly called fluorosilicone. It is a silicone elastomer where a trifluoropropyl group replaces a portion of the methyl groups on the siloxane backbone, giving it fuel and oil resistance that standard VMQ silicone lacks.

What is the temperature range of FVMQ?

FVMQ compounds typically operate from about -60°C / -76°F to 200°C / 392°F longterm, with intermittent peaks to 230°C / 446°F. The exact range depends on the compound: dry air exposure supports the upper end, while continuous fuel or oil contact can lower the practical ceiling.

What is the difference between FVMQ and FKM?

FVMQ is a fluorinated silicone built on a siloxane backbone, while FKM is a fluoroelastomer built on a carbon-fluorine backbone. FVMQ holds a lower temperature floor near -60°C / -76°F and weaker mechanical properties, while FKM handles higher heat, broader chemical resistance, and dynamic sealing that FVMQ cannot.

Is FVMQ the same as silicone?

FVMQ is a modified silicone, not standard silicone. It shares the siloxane backbone with VMQ silicone but adds a trifluoropropyl side group that gives it resistance to jet fuel, hydraulic fluid, and oil that unmodified VMQ silicone does not have.

Can FVMQ be used in dynamic sealing applications?

FVMQ is not recommended for dynamic sealing. Its low tear strength and poor abrasion resistance, measured per ASTM D624 and ASTM D5963, wear quickly under reciprocating or rotary contact, so engineers specify it for static seals and coatings only.

What is FVMQ used for in aerospace?

FVMQ seals, coatings, and sealants protect aircraft fuel system components that combine cold soak with jet fuel exposure, including fuel tank access panel seals, fuel line connector O-rings, and fuel quantity probe seals. Engineers choose it where a part must stay flexible below -40°C / -40°F while resisting Jet A or JP-8.

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