AS568-003 B50 (NBR) Buna-N Nitrile 50 Duro O-Ring

1/16"ID X 3/16"OD X 1/16"CS Buna-N O-Rings 50 Duro (NBR):

The most commonly used elastomer for sealing products. Nitrile, also known as Buna-N or NBR, is a copolymer of Butadiene and Acrylonitirle. It has a temperature range of -40F to +250F and is exceptionally resistant to petroleum base oils and hydrocarbon fuels. Nitrile materials also exhibit excellent tensile strength and abrasion resistance properties. The material performs well with most dilute acids, silicone oils and lubricants and in water applications. It is not recommended for use with ketones, aromatic hydrocarbons and phosphate ester hydraulic fluids. More than 50% of the Orings sold are Nitrile Orings, commonly used in hydraulic/pneumatic motors, cylinders, pumps and valves.

Buna-N / Nitrile Recommended uses:

• General purpose sealing.
• Petroleum oils and fluids.
• Gasoline
• Hydraulic fluids
• L.P. gases
• Cold Water.
• Silicone greases and oils
• Di-ester base lubricants (MIL-L-7808).
• Ethylene glycol base fluids (Hydrolubes)
• Static or Gasket Applications

Nitrile is not recommended for:

• Halogenated hydrocarbons (carbon tetrachloride, trichloroethylene)
• Nitro hydrocarbons (nitrobenzene, aniline)
• Phosphate ester hydraulic fluids (Skydrol, Fyrquel, Pydraul).
• Ketones (MEK, acetone)
• Ozone
• Sunlight, UV
• Weather
• Strong Acids Ozone
• Automotive brake fluid
• Dynamic Applications

Compound Info:

• A general purpose, sulfur-cured Nitrile (Buna-N) compound
• Color: Black
• Duro: 50
• FDA: No
• ASTM D2000-99 Grade M2BG507 A14 B14 EA14 EO34 F17Y

Operating temperature: -40° to +250°F

O-Ring Shelf Life & Storage for NBR O-Rings

The long-term reliability of NBR O-Rings depends heavily on proper storage. While Buna-N has a recommended shelf life of 15 years under SAE-ARP5316 and ISO 2230, that assumes storage in ideal conditions.

At The O-Ring Store, every NBR O-Ring is stored in a dedicated, climate-controlled facility at a stable 72°F year-round. Products are protected from natural light, UV, ozone, excess humidity, and physical stress. Each O-Ring remains sealed in its original packaging until it is shipped, preserving its elasticity and performance.

Why this matters to you: Nitrile rubber deteriorates rapidly when exposed to sunlight, ozone, or poor storage conditions. Even brief exposure outside of a controlled environment can shorten shelf life, leading to hardening, cracking, or permanent deformation.

For this reason, we cannot accept returns once O-Rings leave our facility. A Buna-N O-Ring can begin to deteriorate in just a few hours of direct sunlight. In fact, an O-Ring left on a sunny workbench over a single weekend may already show signs of hardening, surface cracking, or loss of flexibility. Once outside our controlled storage environment, we cannot guarantee how the product was handled, and even brief UV exposure can compromise its long-term reliability. By maintaining strict storage practices, we ensure that every NBR O-Ring you purchase arrives in fresh, reliable condition, ready for immediate use.

Best Practices for Storing NBR O-Rings

If you plan to store O-Rings after delivery, follow these guidelines:

• Keep below 77°F (25°C) in a cool, dry place
• Maintain humidity under 75%
• Protect from direct sunlight and artificial UV sources
• Avoid ozone exposure (from motors, welders, electrical equipment)
• Store without tension or compression (never hang or stack under weight)
• Keep sealed in original packaging until use

Customer Benefit: Every Buna-N O-Ring from The O-Ring Store is kept under ISO 9001:2015 certified storage practices. That means when it arrives, you’re getting the longest usable life and most reliable performance possible, not an O-Ring that’s already aged on someone else’s shelf.