Ace Seal is a global manufacturer of custom o-rings, seals, gaskets and other molded rubber & plastic components

Buna O-Rings, Seals & Gaskets

  • Buna O-Rings | Nitrile O-Ring | Buna-N O-Ring

Buna-N (also known as nitrile or NBR) is a synthetic rubber material. Its versatility makes it an ideal material for o-rings, seals, gaskets, and custom molded components for all industries and applications.

Nitrile is unique among synthetic rubbers in that it is generally resistant to chemicals such as oil and fuel, among other substances such as mineral and vegetable oils, diluted acids, and alkalines. Buna-N o-rings are commonly used in fuel tanks and other components for automotive and aerospace applications where ordinary rubber cannot be used due to its reactivity with fuel/oil/etc. Nitrile’s elongation at break is roughly 300%, and it possesses a tensile strength of ≥10 N/mm2. Additionally, Buna is able to withstand a wide range of temperatures, from −40° to 121°C (−40° to 250°F). This further improves the material’s performance in aerospace applications.

Buna-N is less likely to cause allergic reactions than latex or natural rubber materials, making it popular for medical and dental applications. Nitrile also exhibits greater strength and puncture resistance than latex and natural rubber.

Buna O-Ring Product Options

Ace Seal stocks all AS568 size Buna-N o-rings, as well as an extensive inventory of metric sizes in standard colors and hardnesses. A wide variety of custom durometer, colors, and industry certifications are available upon request.


Buna-N O-Ring Product Features

  • Resistant to: air, alcohols, alkalines, diluted acids, engine coolants, gasoline, water, hydraulic fluids, mineral oil, silicone greases, motor oil, vegetable oil
  • Do not use with: brake fluids, acetones
  • Operational temperature range: -40°F to 250°F (-40°C to 121°C)
  • Hardness range (durometer): 40-90
  • Standard hardness: 70 Shore A
  • Tensile range: 200-3000 psi
  • Maximum elongation: ≈300%
  • Adheres well to metals
  • Standard color: black; custom colors are available upon request
  • Available specifications: FDA, UL, MIL-SPEC, 3/A; other specifications may be available upon request

Chemical Compatibility & Characteristics of Buna-N O-Rings

If Buna-N is not compatible with your application, view our chemical compatibility chart to find the right material for your unique needs

  • Oil resistance: Excellent
  • Dynamic resistance: Good to excellent
  • Set resistance: Good to excellent
  • Tensile strength: Good to excellent
  • Abrasion resistance: Good
  • Cold resistance: Good
  • Heat resistance: Good
  • Impermeability: Good
  • Chemical resistance: Fair to good
  • Water steam resistance: Fair to good
  • Acid resistance: Fair
  • Electrical properties: Fair
  • Tear resistance: Fair
  • Weather resistance: Fair
  • Flame resistance: Poor
  • Ozone resistance: Poor

Contact Us for Buna O-Rings, Seals, Gaskets & More

Ace Seal is your #1 resource for standard and custom nitrile o-rings, seals, gaskets, and molded products. Request a quote today or contact us for more information.