NBR O-Rings

NBR O-Rings - Industrial Sealing Solutions for Hydraulics, Pneumatics and Machinery

NBR O-rings are elastomeric sealing rings manufactured from Nitrile Butadiene Rubber, also known as Buna-N or nitrile rubber. They are among the most widely used technical seals in hydraulics, pneumatics, machine building, automotive systems, OEM production and industrial maintenance. NBR is particularly valued for its resistance to many mineral oils, lubricating greases and compatible technical fluids. At simmering.pl, NBR O-rings are available in a broad range of inside diameters, cross-sections and hardness grades for industrial, maintenance and production applications.

What Are NBR O-Rings?

An O-ring is a closed-loop elastomeric sealing element with a circular cross-section.

It is installed in a specifically designed groove and compressed between mating surfaces. This controlled deformation creates sealing contact and helps prevent leakage of the operating medium.

NBR is one of the most established elastomers used for O-ring manufacturing because it combines useful mechanical properties with resistance to many oils and lubricants commonly encountered in industrial equipment.

For this reason, NBR O-rings are frequently specified for general-purpose industrial sealing.

What Does NBR Mean?

NBR stands for Nitrile Butadiene Rubber.

Other commonly encountered names include:

nitrile rubber
Buna-N
acrylonitrile butadiene rubber

NBR compounds can be formulated with different properties, including different hardness levels and temperature capabilities.

Therefore, not every NBR O-ring should automatically be assumed to have exactly the same operating limits.

NBR O-Rings for Oil and Grease

One of the principal reasons for choosing NBR is its resistance to many mineral oils and lubricating greases.

This makes NBR O-rings particularly relevant to machinery and mechanical systems where sealing elements are exposed to lubricants or compatible hydraulic fluids.

Typical applications include:

hydraulic equipment
pumps
valves
gearboxes
lubrication systems
mechanical housings
industrial machinery
production equipment

NBR should not be considered universally resistant to every oil, fuel or chemical. Compatibility must be evaluated for the actual operating medium and temperature.

NBR O-Rings for Hydraulic Systems

NBR O-rings for hydraulics are widely used in equipment operating with compatible mineral oil based hydraulic fluids.

Depending on the sealing design, they can be used in:

hydraulic valves
manifolds
pumps
fittings
connectors
housings
cylinders
hydraulic assemblies

An O-ring's pressure capability cannot be determined from material alone.

For pressurized hydraulic applications, engineers must also consider groove geometry, O-ring hardness, extrusion clearance, temperature, pressure cycling and the design of the complete sealing system.

Where required by the application, backup rings can be used to help control extrusion.

NBR O-Rings for Pneumatic Systems

NBR is also widely used in pneumatic sealing systems.

O-rings can provide sealing in appropriately designed pneumatic valves, connectors, fittings, housings and control components.

Dynamic pneumatic applications require additional consideration because movement introduces friction and wear.

Important parameters include:

lubrication
operating speed
surface finish
friction
pressure
temperature
seal compression

The correct O-ring must therefore be selected according to the complete operating environment rather than dimensions alone.

NBR O-Rings for Industrial Machinery

Industrial machinery contains numerous interfaces that require compact and replaceable sealing elements.

NBR O-rings can be used in appropriately designed:

machine housings
pumps
hydraulic units
lubrication systems
valves
gearboxes
drive assemblies
production equipment
mechanical components
maintenance assemblies

Their simple geometry and broad dimensional range make O-rings one of the fundamental sealing elements used in machine design and industrial maintenance.

NBR 70 ShA, 80 ShA and 90 ShA O-Rings

O-ring hardness is commonly specified using the Shore A scale.

Depending on the product range and application, NBR O-rings may be available in different hardness grades.

NBR 70 ShA is a widely used general-purpose hardness providing a practical balance between elasticity and resistance to deformation.

NBR 80 ShA provides increased hardness for applications requiring different deformation characteristics.

NBR 90 ShA is significantly harder and may be selected for appropriately engineered applications requiring greater resistance to deformation.

A harder O-ring is not automatically a better O-ring. The correct hardness depends on pressure, groove design, extrusion clearance, movement and other operating conditions.

How Are O-Ring Sizes Specified?

O-rings are normally identified by two fundamental dimensions:

d1 - Inside Diameter (ID)
d2 - Cross-Section (CS)

For example:

32x4 mm

means:

Inside Diameter: 32 mm
Cross-Section: 4 mm

The nominal outside diameter can be calculated using:

OD = ID + 2 x CS

For a 32x4 mm O-ring:

32 + 4 + 4 = 40 mm

Therefore, its nominal outside diameter is 40 mm.

For technical purchasing and replacement, the inside diameter and cross-section are the primary dimensions.

Metric and Inch O-Rings

Industrial sealing systems use both metric O-rings and inch-size O-rings.

Two seals may appear almost identical while having slightly different inside diameters or cross-sections.

These small dimensional differences can significantly affect compression and groove filling.

When identifying an unknown O-ring, it is useful to determine:

inside diameter
cross-section
groove dimensions
mating component dimensions
required elastomer
hardness

An approximately similar size should not automatically be treated as an interchangeable replacement.

Static NBR O-Ring Sealing

O-rings are particularly effective in static sealing applications where no intended relative movement occurs between the sealed surfaces during normal operation.

The O-ring is compressed within its groove, creating sealing contact against the mating surfaces.

Typical static applications include:

covers
housings
flanges
fittings
valve bodies
pump components
hydraulic assemblies

Reliable static sealing depends on correct groove dimensions, compression, material compatibility, pressure and surface condition.

Dynamic NBR O-Ring Sealing

NBR O-rings can also be used in appropriately engineered dynamic sealing applications.

Dynamic service introduces additional challenges because one surface moves relative to the seal.

Engineers must consider:

friction
lubrication
operating speed
surface finish
temperature
pressure
extrusion clearance
elastomer wear

An O-ring arrangement intended for static sealing should not automatically be considered suitable for dynamic operation.

NBR O-Ring Temperature Range

The operating temperature of an NBR O-ring depends on the specific rubber compound.

For many standard NBR compounds, a range of approximately -30 to +100°C is commonly used as a general reference.

Special NBR formulations may have different operating capabilities.

Actual temperature limits depend on factors including:

compound formulation
operating medium
exposure duration
pressure
mechanical load
ageing conditions

For higher-temperature applications, another elastomer such as FKM may be considered when its properties match the operating environment.

NBR vs FKM, EPDM and Silicone O-Rings

There is no single O-ring material that is optimal for every application.

NBR: commonly selected for many mineral oils, lubricating greases and general industrial applications.

FKM/FPM: often selected where higher temperature capability or resistance to particular chemicals is required.

EPDM: commonly used with water and other compatible media but generally not selected for mineral oil applications.

MVQ/Silicone: offers properties useful in applications requiring the characteristics of silicone elastomers.

Material selection should always be based on the operating medium, temperature, pressure and mechanical requirements.

How to Select the Correct NBR O-Ring

Correct O-ring selection requires more than matching a diameter.

The following parameters should be checked:

1. Inside Diameter

The O-ring must correspond to the dimensions and geometry of the assembly.

2. Cross-Section

Cross-section directly affects compression and groove filling.

3. Material

Verify that NBR is chemically compatible with the operating medium.

4. Hardness

Select the Shore A hardness required by the sealing design.

5. Temperature

Confirm that the specific NBR compound is suitable for the operating temperature.

6. Pressure

Pressure must be evaluated together with groove design and extrusion clearance.

7. Static or Dynamic Operation

Dynamic applications require additional consideration of friction, lubrication, speed and wear.

Why O-Ring Groove Dimensions Matter

An O-ring seals through controlled deformation.

If the groove is too deep, the O-ring may receive insufficient compression and sealing contact.

If the groove is too shallow, excessive compression can increase deformation, friction and assembly forces.

Groove width is also important because the elastomer requires sufficient space to deform when compressed.

For pressurized applications, extrusion clearance between mating components becomes another important design parameter.

This is why selecting an O-ring solely from an approximate shaft, bore or outside diameter can result in incorrect sealing conditions.

O-Ring Compression and Groove Filling

Compression and groove filling are fundamental parameters in O-ring design.

The required values depend on whether the seal operates in a static, reciprocating, rotary or other specialized arrangement.

Too little compression can result in insufficient sealing contact.

Excessive compression can increase stress, friction and permanent deformation.

The correct groove dimensions should therefore be established according to the application rather than estimated from the O-ring dimensions alone.

Installation of NBR O-Rings

Before installing an O-ring, inspect the groove and mating surfaces.

The sealing ring should not be:

twisted
cut
excessively stretched
pinched during assembly
pulled unprotected across sharp edges
installed over contamination or debris

Threads, keyways, splines and sharp shoulders can damage the elastomer during installation.

Where an assembly lubricant is used, it should be compatible with both the NBR compound and operating medium.

Common Causes of O-Ring Failure

O-ring failure is not always caused by the seal itself.

Typical causes can include:

incorrect material selection
incompatible operating fluid
incorrect groove dimensions
excessive compression
insufficient compression
extrusion under pressure
installation damage
excessive temperature
poor surface condition
inadequate lubrication in dynamic service
twisting during assembly

Examining the failed O-ring and the sealing environment can help identify the underlying cause before a replacement is installed.

NBR O-Rings for OEM Production

O-rings are frequently used as repeat components in OEM manufacturing and serial production.

For production applications, consistent specification is essential.

Technical purchasing should identify the required:

dimensions
NBR material
hardness
application conditions
quantity
packaging requirements

Maintaining the correct sealing components in production stock helps support assembly continuity and reduces the risk of shortages interrupting manufacturing.

NBR O-Rings for MRO and Maintenance

O-rings are also fundamental MRO components used during machine maintenance, repairs and scheduled overhauls.

Maintenance departments commonly use NBR O-rings for:

hydraulic repairs
pump servicing
valve maintenance
machine rebuilding
lubrication systems
preventive maintenance
emergency repairs

Maintaining a structured inventory of frequently used sizes can reduce repair time and improve spare-part availability.

NBR O-Rings for B2B and Technical Purchasing

The NBR O-ring category is relevant to technical buyers, machine manufacturers, industrial maintenance teams, workshops and distributors requiring recurring access to sealing components.

Typical B2B users include:

OEM manufacturers
industrial plants
machine builders
maintenance departments
MRO organizations
repair workshops
technical distributors
resellers
spare parts warehouses
industrial purchasing departments

A broad dimensional range enables O-rings to be selected for both compact technical components and larger industrial assemblies.

Storage of NBR O-Rings

Elastomeric seals should be stored under conditions that limit premature ageing.

NBR O-rings should be protected against:

direct sunlight
UV radiation
ozone
excessive heat
aggressive chemicals
permanent stretching
mechanical deformation

They should preferably remain in suitable packaging until required for installation.

Correct storage is particularly important for OEM, MRO and industrial customers maintaining larger warehouse inventories.

How to Find the Correct NBR O-Ring

If the dimensions are known, an effective search format is:

Inside Diameter x Cross-Section + Material

For example:

O-Ring 32x4 NBR

If a particular hardness is required:

O-Ring 32x4 NBR 70 ShA

This search structure clearly identifies the three most important purchasing parameters: dimensions, material and hardness.

If the dimensions are unknown, measure the original O-ring carefully and, where possible, verify the groove dimensions before ordering.

NBR O-Rings for Industrial Supply

For industrial users, O-rings are often recurring consumable components rather than occasional spare parts.

The correct sealing inventory can support:

continuous production
scheduled maintenance
emergency repairs
OEM assembly
workshop operations
spare parts management
technical distribution

For frequently consumed sizes, maintaining warehouse stock can reduce purchasing frequency and improve component availability.

FAQ - NBR O-Rings

What is an NBR O-ring?
An NBR O-ring is a circular elastomeric sealing ring manufactured from Nitrile Butadiene Rubber. It is widely used for sealing applications involving many mineral oils, greases and compatible industrial fluids.

Are NBR O-rings oil resistant?
NBR provides good resistance to many mineral oils and lubricating greases. Compatibility should always be checked for the specific oil, additives and operating temperature.

Are NBR O-rings suitable for hydraulics?
Yes. NBR O-rings are widely used in hydraulic systems operating with compatible fluids. Correct dimensions, hardness, groove geometry and operating conditions must also be considered.

What does NBR 70 ShA mean?
NBR identifies the elastomer, while 70 ShA indicates a nominal hardness of 70 on the Shore A scale.

How do I measure an O-ring?
The two primary dimensions are the inside diameter and cross-sectional diameter.

What does 32x4 mean on an O-ring?
It normally means a 32 mm inside diameter and a 4 mm cross-section.

Can I replace an O-ring with a slightly different size?
Not automatically. Even a small cross-section difference can significantly change compression and groove filling.

Are NBR O-rings suitable for high temperatures?
Temperature capability depends on the specific NBR compound. Standard NBR is generally intended for moderate temperatures, while other elastomers may be more appropriate for higher-temperature service.

Can NBR O-rings be used dynamically?
Yes, in appropriately designed applications. Friction, lubrication, speed, surface finish, pressure and wear must also be evaluated.

Are NBR and Buna-N the same material?
Buna-N is a commonly used name for NBR, or Nitrile Butadiene Rubber.

Frequently Asked Questions by Engineers

Is the inside diameter enough to identify an O-ring?
No. At minimum, both the inside diameter and cross-section should be identified. Material and hardness are also important for technical selection.

Does a harder O-ring always provide better high-pressure sealing?
No. Hardness is only one factor. Groove geometry, extrusion clearance, pressure, temperature and operating conditions also determine sealing performance.

Can NBR and FKM O-rings be used interchangeably?
Not automatically. They have different chemical and temperature characteristics. Material substitution requires evaluation of the actual operating environment.

What causes O-ring extrusion?
Pressure can force elastomer into the clearance between mating components. The risk depends on pressure, clearance, hardness, temperature and sealing geometry.

Why is O-ring cross-section so important?
Cross-section directly affects compression, groove filling and sealing contact. Using an incorrect cross-section can cause leakage, excessive deformation or assembly problems.

Should an NBR O-ring be lubricated before installation?
A compatible assembly lubricant can help reduce installation friction and damage, but it must be suitable for both the NBR elastomer and the operating medium.

Why can two O-rings with the same dimensions perform differently?
O-rings can differ in compound formulation, hardness and other material properties even when their nominal dimensions are identical.

NBR O-Rings - Warehouse and Store in Lublin

Availability: 4 pcs.

Mark: GRN

Diameter in. (mm): 125

Thickness (mm): 5

Package: 100 pcs.

€51.32 (net)

Price for: 100pcs.

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