FKM O-Ring

FKM (Viton) rubber is widely used in automotive engine and fuel systems because of its good resistance to oil, high temperature.

Table of content
  • FKM (Viton) Material Property
  • O-RING Size Calculation
  • Working Temperature Range​
  • Chemical Resistance​
  • O-Ring Lubrication
  • O-Ring Color
  • Typical Applications​

FKM (Viton) Material Property

Characteristic Unit Test methodStandard
 range		Typical value
Physical properties    
Hardness Shore A PointASTM D224070±572
Tensile strength MPaASTM D412≥1014
Elongation at break %ASTM D412≥150210
Comprehension set
70h at 200℃		%ASTM D 395≤2523
Low temperature properties
Tg by DSC		℃ASTM D3418≤-15-17
Fluid resistance ASTM D471  
ŸVolume change after 70h at 150℃ in%  
– Oil 901 0/+81
– Oil 902 0/+81
– Oil 903 0/+83
Ÿ Volume change after 70h at 150℃ in%  
– Liquid A   
– Lquid B 0/+81
– Liquid C 0/+82
  0/+84

Working Temperature Range

Temperature range : –20°C /-40°C to 200°C

Low temperature performance of FKM(Viton) is poor, special application may need low temperature FKM material with higher cost.

Chemical Resistance

ChemicalResistance RatingTemperature RangeNotes
AcetonePoorUp to 100°CLimited resistance; avoid prolonged exposure.
MethanolGoodUp to 150°CSuitable for intermittent contact.
Hydrochloric Acid (10%)FairUp to 80°CAvoid high concentrations and elevated temperatures.
Sulfuric Acid (50%)GoodUp to 120°CResistant to diluted solutions; avoid concentrated forms.
Diesel FuelExcellentUp to 200°CHighly resistant to hydrocarbons and fuels.
Hydraulic OilsExcellentUp to 200°CCompatible with most mineral and synthetic oils.
Ammonia (aqueous)PoorUp to 60°CPoor resistance; degradation occurs rapidly.
Ethylene GlycolExcellentUp to 150°CResistant to antifreeze and coolant fluids.
BenzeneGoodUp to 150°CLimited swelling; suitable for short-term exposure.
Sodium Hydroxide (30%)FairUp to 80°CAvoid prolonged exposure to strong alkalis.
Chlorinated SolventsPoorUp to 60°CSevere swelling and chemical attack (e.g., dichloromethane, chloroform).
OzoneExcellentUp to 200°COutstanding resistance to oxidation and ozone.

O-RING Size Calculation

The selection of O-rings primarily depends on compression ratio because it directly impacts the sealing performance, durability.

Formula for Compression Ratio

The compression ratio () of an O-ring is calculated using the following equation:

C=(CS−Gd)/CS × 100%

Where:

  •  = Cross-sectional diameter of the O-ring (mm or inches)

  •  = Groove depth (mm or inches)

Acceptable Compression Ratio Guidelines

Application TypeRecommended Compression Ratio 
Static Seals15% – 30% 
Dynamic Seals10% – 20% 
High-Pressure Seals20% – 30% 

O-Ring Lubrication

Surface coatings are applied to O-rings to enhance their performance in demanding applications. The primary purposes include:

  1. Friction Reduction: Minimize assembly force.

  2. Chemical Resistance: Protects against aggressive media (acids, solvents, fuels).

Coating Materials

Coating MaterialKey PropertiesColor 
PTFE (Polytetrafluoroethylene)– Ultra-low friction (μ ≈ 0.05–0.1)
– Chemical inertness
– Temp range: -60°C to +260°C		 Light white
Lubricate FP(PFPE based lubricating fluid)– Low friction
– Prevent the O-rings from twisting
– Compatible with cleanness requirements 
– NO impact on the mechanical properties of the rubber 
 Transparent
Molybdenum Disulfide (MoS₂)– Low friction
– Anti-galling		 Dark grey

O-Ring Color

Different color can be chosen for easlier identification.

  • Black
  • Blue
  • Green
  • White
  • Red

Typical Applications

  • Automotive – Engine System
  • Automotive – Fuel System
  • Semi-conductor Industry
  • Oil&Gas Industry

Thanks to contact us to discuss your requirements regarding O-RINGs. We are ready to assist you with fast, reliable support.