Buna Nitrile O-Ring Material Description


Nitrile rubber (NBR) o-rings, also known as Buna-N, are one of the most commonly used sealing elastomers due to resistance to petroleum-based fuels and lubricants and its relatively low price. Nitrile elastomers are copolymers of acrylonitrile and butadiene. There are a number of common variations of nitrile compounds. Nitrile o-rings may also come in a metal detectable variation, while retaining the same qualities as the general Nitrile o-ring compound.

Nitrile o-rings are preferable for use with petroleum-based oils and fuels, aliphatic hydrocarbons, vegetable oils, silicone oils and greases, ethylene glycol, dilute acids, and water (up to 212ºF). Nitrile o-rings are not preferable for use with aromatic hydrocarbons, chlorinated hydrocarbons, brake fluid, ketones, ethers, esters, phosphate ester hydraulic fluids, strong acids, and conditions requiring weather resistance.

Acrylonitrile Content

The acrylonitrile (ACN) content of the polymer chains can vary from 18% to 50%. Lower ACN content gives better low-temperature properties but inferior resistance to fuels and polar lubricants. Higher ACN content gives lesser quality low-temperature properties but improved fuels and polar lubricants resistance. Standard NBRs typically have 34% ACN content.

Cure System: Sulfur-Cured & Peroxide-Cured

Standard Nitrile o-rings are usually sulfur-cured. Sulfur-cured compounds offer better low-temperature properties but are more prone to hardening with high temperatures. Peroxide-cured nitrile o-rings have better heat resistance and lower compression sets but are more expensive and more difficult to process. Standard materials in stock include sulfur-cured 70 & 90 durometer (N70, N90) and peroxide-cured 90 durometer (N90PC)

Temperature Range (Typical Compounds)


Standard Low Temp: -40°C (-40°F)
Standard High Temp: 100°C (212°F)

SPEC SHEET: Nitrile 70 Durometer

SPEC SHEET: Nitrile 70 Durometer – Metal & X-Ray Detectable

SPEC SHEET: Nitrile 90 Durometer


Standard Low Temp: -29°C (-20°F)
Standard High Temp: 135°C (275°F)

SPEC SHEET: Nitrile 90 Durometer – Peroxide-Cured

Low-Temp Buna Nitrile O-Rings:

N70LT Low Temp: -55°C (-67°F)
N70LT High Temp: 100°C (212°F)

SPEC SHEET: Nitrile 70 Durometer Low-Temp


Product Inquiry