Nitrile Buna-N

Nitrile rubber — often referred to as Buna‑N or NBR (Acrylonitrile‑Butadiene Copolymer) — is one of the most widely used and cost‑effective elastomers in industrial sealing and gasketing applications.

NBR’s popularity stems from its balanced combination of mechanical performance, chemical resistance, and versatility, making it a go-to choice for a broad range of sectors, including automotive, aerospace, marine, oil & gas, hydraulics, and general industrial use.

Key Material Properties

Strengths & Advantages

• Oil, fuel and chemical resistance – NBR performs exceptionally well when exposed to petroleum‑based oils, hydrocarbon fuels, hydraulic fluids, silicone greases, water, and alcohols.
• Mechanical robustness – It offers a good balance of tensile strength, tear resistance, abrasion resistance and overall durability.
• Elasticity and sealing performance – With good compression set behaviour and flexibility (depending on compound), it is ideal for dynamic and static seals, gaskets, O‑rings, hoses and other sealing elements.
• Customisable properties via formulation – By varying the acrylonitrile (ACN) content and using different compounding techniques (e.g. carboxylated Nitrile), properties can be tailored (e.g. greater oil resistance, improved abrasion resistance, low‑temperature flexibility).
• Wide hardness and use‑temperature range – Typical Shore A hardness spans ~ 40–90, enabling a broad selection from soft, flexible seals to rigid, heavy‑duty gaskets.

As a copolymer of acrylonitrile and butadiene, NBR’s exact performance depends on the proportion of those monomers — higher acrylonitrile content generally increases strength, oil resistance and reduces permeability to gases.

Typical Applications

NBR is a versatile material that appears in many industries, such as:

• Seals, O‑rings, gaskets and hose systems in automotive, marine, and aircraft fuel and oil systems (approved grades only, not generic NBR)
• Hydraulic systems, pumps, valves and hydraulic hose assemblies owing to its resistance to hydraulic fluids and lubricants.
• Industrial sealing, general mechanical gaskets, O‑rings, floor mats, hoses, and vibration dampers where abrasion resistance and mechanical strength are important.
• Food‑processing / pharmaceutical‑safe seals when formulated to comply with regulatory standards (e.g. FDA compliance) — ideal for food, beverage or sanitary applications.
• Low‑temperature, off‑road and military applications, especially when using low‑ACN or low‑temperature variants, where elasticity at low temperatures is required.

Summary — When to Choose Nitrile / Buna‑N

Choose NBR (Buna‑N) when you need a cost‑effective, durable, oil- and fuel-resistant elastomer for seals, gaskets, O‑rings, hoses or other sealing elements — especially in oil/fuel/hydraulic systems, automotive and industrial equipment, and standard mechanical sealing tasks.

For applications involving food processing or sanitary requirements, a food‑grade NBR formulation is often available. For low‑temperature or high‑abrasion usage, or where strong hydrocarbons are involved, using a low‑temp or high‑nitrile (high ACN) variant will bring better performance.

However, if your application involves high exposure to ozone, UV/ sunlight, aggressive chemicals (solvents, ketones, acids, etc.), or high continuous temperatures, then you may need to consider alternative rubber/elastomer materials more suited to those conditions.

Looking for an alternative style?  Click here to contact our Sales team.

These compounds are attacked by small amounts of Ozone. Phthalate type plasticizers are commonly used in compounding Nitrile rubber. These plasticizers can migrate out and cause problems with certain plastics. Also, new regulation on certain phthalates have limited their use.

You can buy British Standard NBR70 O-rings and NBR-90 O-rings in our online store. Shop for NBR O-rings now.

Please note: This Material Data Sheet section is to be used as a professional guide only. Eastern Seals (UK) Ltd may source their products from a variety of Quality Approved Suppliers and the data shown should not be relied upon by any purchaser without verification of material source.

ES REF	Colour	Temp Range	Hardness	Notes	Data Sheet
N50	BLACK	-35°C to +110°C	50	General purpose Nitrile.	N50
N60	BLACK	-35°C to +110°C	60	General purpose Nitrile.	N60
N70	BLACK	-35°C to +110°C	70	General purpose Nitrile.	N70
N70 FDA	BLACK	-35°C to +110°C	70	Compliant To FDA Regulation Cfr 21 177-2600	N70 FDA
N70 FDA	WHITE	-35°C to +125°C	70	Compliant To FDA Regulation Cfr 21 177-2600	N70 FDA (white)
N70 WRAS	BLACK	-35°C to +110°C	70	WRAS Approved N70	N70 WRAS
N70 LT	BLACK	-45°C to +110°C	70	Low Temperature type Nitrile	N70LT (low temp -45°C)
N70H (High Nitrile)	BLACK	-35°C to +110°C	70	High Nitrile – 40% A.C.N content	N70H (High Nitrile)
N70 for Cord	BLACK	-25°C to +100°C	70	General purpose Nitrile.	N70 Cord
N70BLMD	BLUE	-15°C to +110°C	70	METAL DETECTABLE. Developed to support use of Nitrile rubber in food processing applications. The material is electrically conductive. This material has been formulated using only those ingredients determined by the United States Federal Food and Drug Administration (FDA) to be in accordance with Code of Federal Regulations Title 21 (CFR21), Section 177.2600. Fragments as small as 2mm can be identified by in-line metal detection and X-ray equipment.	N70BLMD
N70BLMD FDA	BLUE	-15°C to +110°C	70	NITRILE 70 SHORE BLUE METAL DETECTABLE FDA (COMPLIES TO CFR 21 177-2600)	N70BLMD FDA
N70 (rotary shaft seals)	BLACK	-35°C to +110°C	70	General purpose Nitrile.	N70 for rotary shaft seals
N80	BLACK	-35°C to +110°C	80	General purpose Nitrile.	N80
N90 FDA	BLACK	-35°C to +110°C	90	Complies With FDA Regulation 21 CFR177.2600	N90 FDA
N85 (Bonded Seals)	BLACK	-35°C to +110°C	85	Nitrile for Bonded seals.	N85 (bonded seals)
N90	BLACK	-35°C to +110°C	90	General purpose Nitrile.	N90
N90H (High Nitrile)	BLACK	-35°C to +110°C	90	High Nitrile – 40% A.C.N	N90H (High Nitrile)