Dec 10 2024
Mechanical Seal vs. Oil Seal: What's the Difference?
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In the realm of industrial sealing solutions, choosing the right material for O-rings and seals is critical to ensuring system integrity, longevity, and performance. Buna and Viton seals represent two of the most widely used elastomers. In this blog，we will compare the advantages and limitations of each to ensure you select the best seal to optimize your application.
Composed primarily of fluorocarbon polymers with high fluorine content, Viton O-rings feature strong carbon-fluorine bonds that contribute to their robustness.
High Temperature Resistance: Viton compounds can withstand continuous temperatures up to 400°F (204°C) and short-term exposures as high as 600°F (315°C).
Superior Chemical Resistance: Resists fuels, petroleum oils, acids, solvents, ozone, UV, weathering, and even harsh disinfectants like bleach, making it ideal for chemically demanding environments.
Low Compression Set and Outgassing: With a low compression set, Viton maintains its shape under prolonged pressure, ensuring reliable sealing.
Mechanical Strength: Typical durometer ratings range from 60 to 90 Shore A, with tensile strength between 500 and 2,000 psi and maximum elongation up to 300%. It offers excellent abrasion and tear resistance, contributing to durability in dynamic sealing scenarios.
Buna, also known as Buna-N or nitrile rubber (NBR), is an economical, oil-resistant synthetic rubber valued for its tensile strength and excellent resistance to fuels and oils. It performs reliably from –30 °F (–34 °C) to 250 °F (121 °C), with some grades effective down to –40 °F. Compared to Viton, Buna O-rings offer better flexibility and sealing performance in low-temperature environments.
Temperature Range: Buna operates effectively from -30°F (-34°C) to 250°F (121°C), with some formulations handling down to -40°F. It remains flexible in cold environments without becoming brittle, outperforming Viton in low-temperature scenarios.
Excellent Resistance to Oils and Fuels: Buna provides superior compatibility with petroleum-based oils, hydraulic fluids, silicone greases, alcohols, and water. It's particularly effective in ethanol/methanol-blended gasoline and shows low permeability to gases and liquids.
Mechanical Durability: With durometer ratings from 20 to 95 Shore A, tensile strength ranging from 200 to 3,000 psi, and elongation up to 600%, Buna offers high abrasion resistance, tear strength, and good adhesion to metals. Its low compression set ensures reliable sealing under stress.
Abrasion and Wear Resistance: Buna's robust structure makes it suitable for applications involving mechanical friction or deformation, providing better performance than natural rubber in heavy-duty uses.
Cost-Effectiveness: As a synthetic rubber, Buna is more economical to produce, making it a go-to for budget-conscious projects without sacrificing essential properties in moderate conditions.
However, Buna is less resistant to ozone, weather, and certain chemicals, which can lead to cracking or degradation if not properly protected.
Buna N is an economical, versatile material suitable for applications involving oil, fuel, and hydraulic fluids. On the other hand, Viton provides superior resistance to harsh chemicals, making it a top choice for chemical processing and oil & gas applications. The most significant difference between the two lies in their temperature range. Here’s a detailed comparison to help guide your selection:
| Aspect | Viton O-Rings | Buna O-Rings |
| Temperature Range | Up to 400-600°F; brittle below -4°F | -30°F to 250°F; flexible in cold |
| Chemical Resistance | excels with acids, solvents, ozone, UV, bleach | Strong with oils, fuels, hydraulics; weaker against ozone, weather, harsh chemicals |
| Cost | Higher | Economical |
| Mechanical Strengths | Low compression set; abrasion resistance | High elongation (up to 600%); tear resistance |
At Gangwei Rubber, we specialize in manufacturing top-tier rubber seals tailored to your exact specifications. With years of experience, we deliver seals that meet strict quality standards and perform reliably in aerospace, automotive, chemical, and industrial applications. Whether you need standard O-rings or custom gaskets, our team can guide you through material selection, prototyping, and production.
We're committed to delivering seals that enhance your application's efficiency and durability—contact us today for personalized solutions.
