Delivering Fluid Sealing Solutions Since 1972

Nitrile O Rings (NBR)

The UK’s largest selection of Nitrile O Rings (NBR)

M Barnwell Services range of Nitrile O Rings (NBR O Rings) offer good mechanical properties and resistance to mineral oil-based lubricants and greases. NBR O Rings provide excellent resistance to fuels and are available in a wide variety of shore hardness and specialist compounds.

We have over 50 million O Rings and Back-Up Rings in stock servicing many industries. they include Water, Pump and Gas, Agriculture, Food and Drink, Rail, Automotive and Bus Truck and Trailer.

Nitrile O Rings

About Nitrile O Rings and its Features:

Nitrile elastomer (NBR) is the overall definition for Acrylonitrile Butadiene Copolymer. It’s an economical elastomer that is very popular and extensively used. Nitrile O Rings are available in a Black colour as standard with a hardness of between 40 and 90 Shore A. They can withstand the temperatures between -40°C and +135°C (intermittent/compound-specific up to +150°C), however, can be formulated for temperatures ranging between -65°C and +120°C (low-temperature). Nitrile O Rings contain the copolymer butadiene and acrylonitrile in fluctuating ratios. Compounds that have a Nitrile (ACN) content of approx. 32% are called “Medium Nitrile” and are the most popular. Compounds with approx. 50% of Nitrile (ACN) content are called “High Nitrile”. These elastomers are commonly recommended for use with Hydrocarbon fuels. Compounds with approx. 18% of Nitrile (ACN) content are called “Low Nitrile”. They are mostly defined for use in low-temperature applications.

Key Uses of Nitrile O Rings:

Marine, aircraft and automotive fuel structure, off-road equipment, oil resistant applications of all types, low-temperature military uses. Furthermore, it can be compounded to Hygienic FDA applications. Nitrile combines superb resistance to petroleum-based oils and fuels, hydraulic fluids, water, alcohol and silicone greases. It also presents a great balance of working properties such as low compression set, high abrasion resistance, and high tensile strength.


Nitrile O Ring compounds are, however, confronted by a slight quantity of Ozone. A commonly used compound in Nitrile rubber is a phthalate type plasticizer that can migrate out and generate issues with some plastics. In addition, new regulations on some phthalates have limited their use.

For further details about Nitrile (NBR) O Rings visit our Material Properties page.

If you would like more information about our range, download our catalogue, see Nitrile Comparison Chart or contact a member of the team.

E & OE.


No limitation to dimensions with over 10,000 different sizes available from stock.


Nitrile (NBR), Buna-N

Temperature Range

Between -40°C and +135°C (intermittent/compound-specific up to +150°C)
Can be formulated for temperatures ranging between -65°C and +120°C (low-temperature)


Between 40 and 90 (Shore A)


O Ring Metric & Imperial Kits, Selection Boxes, Splicing Kits & Top-up Bags available.
Bespoke O Ring Kits and Selection Boxes also available.

Associated Products

Encapsulated ORings (FEP/PFA), Lube, Gauge / O Ring material tester, Quad Rings® (X-Rings), Nu-lip Rings, O Ring Cord, Tube, Anti-Extrusion Rings, Splicing Kits, Back-up Rings, Lubricants & Adhesives