Viton™ vs. Buna: Which Seal is Right for Your Application?
Viton™ and Buna are two of the most commonly used elastomers for sealing applications. Both serve as great general-purpose sealing options that offer excellent compression set resistance. Viton and Buna are designed to resist most oils and lubricants, especially petroleum-based lubricants, and can withstand temperatures of 5-250°F.
Both sealing options suit diverse applications and serve as excellent general-purpose seals. It’s important to consider the advantages and limitations of each to ensure you select the best seal to optimize your application.
What are Viton Elastomer Seals?
Viton is a fluoroelastomer polymer that offers the highest level of fluid resistance of any commercial rubber. It’s known for its ability to retain good mechanical properties in high temperatures compared to other elastomers. Viton can also remain elastic in applications that regulate hot oil and chemicals. Viton comes in different chemical compositions that vary based on the grade of the elastomer.
Viton Temperature Rating
This elastomer is known for its stability and composition in the presence of high temperatures. Viton seals can provide an indefinite seal for temperatures up to 400°F and an excellent seal for up to 48 hours at temperatures up to 600°F. That allows seals and gaskets to maintain elasticity and prevent leaks during operation in harsh environments. Viton isn’t as effective at low temperatures and can become brittle if operating conditions drop below -4°F.
Chemical Compatibility
Viton’s high fluorine content makes it resistant to virtually all chemicals, fuels and oils. That makes it a strong consideration for applications involving aggressive media. Viton seals also boast excellent resistance to oxidation, ozone, UV exposure, weather, fungus and mold.
Durability and Longevity
These seals are made of fluorocarbon base polymers that include carbon-fluorine bonds that give them strength and durability. Its ability to withstand high thermal stress without degrading can reduce the lifetime costs associated with maintenance and replacement. Viton can handle more aggressive fluid for longer intervals, increasing safe operation and adherence to environmental regulations.
Common Applications
Viton seals and gaskets are found in fuel and hydraulic systems, engines, pumps, valves, motors and pipelines.
Various industries use these seals, including:
- Automotive
- Aerospace
- Gas and oil
- Industrial processing
- Pharmaceutical and medical
What are Buna Elastomer Seals?
Buna seals are made of butadiene and acrylonitrile. They’re often referred to as nitrile or Buna-N elastomers and offer high tensile strength and resistance to fuel and oil. Buna is less expensive than fluoroelastomers, making it a cost-effective option without having to sacrifice durability. It performs well in applications that require adhesion to metal and provides better abrasion resistance than natural rubber.
Buna Temperature Rating
Buna is effective in temperatures from -20 to 225°F, so it can perform in moderately high heat. While they don’t excel in extremely high temperatures like Viton, they are the preferred low temperature sealing option. Buna is known for its ability to remain flexible in freezing environments without hardening, which contributes to an increased service life.
Chemical Compatibility
Buna can handle petroleum-based oils and fuels, greases, silicone oils, alcohols and hydraulic fluids. While also boasting some chemical compatibility, Buna is much less universally resistant than Viton as it can suffer degradation from weather and ozone exposure. For most circumstances, however, Buna offers superior abrasion and tear resistance, making it more suitable for heavy-duty industrial applications.
Durability and Longevity
Buna seals can withstand mechanical stress from compression and deformation while retaining elasticity. That makes them reliable elastomers in high-stress applications with moderate operating temperatures. This type of seal can handle prolonged exposure to high-pressure systems, so you don’t have to worry about frequent replacement. Buna offers low permeability to gases and liquids, too, which creates a long-lasting seal performance.
Common Applications
Buna elastomers are suitable for:
- Pneumatic systems
- Pipe and valve seals
- Fuel system components
- Chemical processing
You’ll find these seals in the following industries:
- Industrial processing
- Medical equipment
- Food and beverage
- Oil and gas
Find Viton and Buna Elastomers at Humphrey Products
As an industry-leading valve manufacturer, Humphrey Products is committed to offering a diverse lineup of valves to suit your needs. For more info on Viton and Buna seals in pneumatic and fluid handling valves call 1-800-477-8707 or email us at webcust@humphrey-products.com.