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FKM fluoroelastomer (Viton)
FKM is a fluoroelastomer, sold under trade names such as Viton, and the premium choice for seals exposed to heat, fuels, oils and aggressive chemicals. Standard compounds serve from about −15 to 400 °F (−26 to 204 °C) and range from 60 to 90 Shore A. FKM resists aromatic fuels, most acids and ozone. It costs roughly 5–10× nitrile and stiffens in the cold.
- ISO 1629
- FKM
- ASTM D2000
- HK class (e.g., M2HK 710)
- AMS
- AMS-R-83248 (FKM O-rings)
- Trade name
- Viton (Chemours)
How does it compare?
Typical room-temperature values for FKM, against all 48 materials in the library.
- Tensile strength
- 12 MPa4th pct
- Density
- 1.85 g/cm³43th pct
- Max service temp
- 204 °C76th pct
- Elongation
- 200 %86th pct
- Relative cost
- $$$$$
Bars are relative to the strongest, densest or hottest material in the SSG library. Percentile vs all 48 materials.
- Density
- 1.85 g/cm³ · 0.0668 lb/in³
- Tensile strength
- 12 MPa · 1.7 ksi
- Elongation
- 200%
- Hardness
- Shore 60–90A
- Max service temperature
- 204 °C · 399 °F
When should you use FKM?
Strengths
- Continuous service to about 400 °F (204 °C)
- Resists fuels including aromatics and gasoline blends, oils and most acids
- Excellent ozone, weather and flame resistance
- Low compression set at temperature in O-ring compounds
- Low gas permeability for fuel-system seals
Watch for
- Expensive: compound cost roughly 5–10× nitrile
- Standard grades stiffen below about −15 °F (−26 °C); low-temperature types cost more
- Attacked by ketones, low-molecular-weight esters, amines, hot water and steam, and glycol brake fluid
Typical parts
- Fuel system O-rings and seals
- Chemical pump and valve seals
- Engine and turbocharger seals
- Semiconductor and vacuum seals
- High-temperature oil seals
- Flue gas and exhaust gaskets
How FKM is made into parts
Cost, finishes and design rules for each process in this material.
What does a part in FKM cost?
A representative part, rubber. Raw material at about $55.00/kg is one line of it; process time and tooling usually matter more.
Extruded seal · Rubber
Order total $64,582
- Tooling
- $750
- one-time, spread over the order
- Piece price
- $12.70
- before setup + tooling
- Lead time
- 3–4 weeks
- to first production
Size
Drag a row to adjust · click to type
Profile width / OD12.012.0 mm
Hollow / ID7.007.00 mm
Cut length900900 mm
Quantity
Price per part falls as volume rises
Exact quantity50005000 pcs
Material
Design checks pass
Open in builderBudgetary estimate for a representative part. Firm quotes come from principals after drawing review.
Compared head to head
FKM questions
Is Viton the same as FKM?
Viton is a brand of FKM fluoroelastomer; other manufacturers make FKM under their own names. Drawings should call out FKM with an ASTM D2000 line callout or AMS spec rather than a brand, unless the brand is required.
What is Viton not compatible with?
Standard FKM swells or degrades in ketones such as acetone and MEK, low-molecular-weight esters, amines, hot water and steam, glycol-based brake fluid, and phosphate-ester hydraulic fluids. EPDM is usually the better choice for those.
FKM vs FFKM?
FFKM (perfluoroelastomer, such as Kalrez) resists nearly all chemicals and serves to about 600 °F (315 °C), at many times the cost of FKM. It is used in semiconductor and chemical processing where FKM fails.
What color are Viton O-rings?
Black and brown are most common. Color does not identify the compound; confirm it by certification, not appearance.
Similar materials
Quote it in FKM.
Upload CAD or start from a template. The builder prices it in this material and the alternatives.