O-Ring NBR 113x5.5 70 Shore A

O-Ring NBR 113x5.5 mm 70 Shore A - Nitrile Rubber Sealing Ring

O-ring NBR 113x5.5 mm 70 Shore A is an elastomeric sealing ring with a nominal inside diameter of 113 mm and a circular cross-section diameter of 5.5 mm. Manufactured from nitrile butadiene rubber (NBR) with a nominal hardness of 70 Shore A, it is designed for installation in a correctly dimensioned sealing groove. NBR is widely used in industrial sealing applications involving mineral oils, lubricating greases and compatible hydraulic fluids.

Technical Specifications - O-Ring NBR 113x5.5 mm

The nominal outside diameter of 124 mm is calculated from the inside diameter and twice the cross-section diameter.

It is a geometric value, not a separately verified catalogue dimension.

Exact dimensional tolerances, temperature limits, chemical compatibility and permissible pressure conditions depend on the specific NBR compound and manufacturer's specification.

What Does O-Ring 113x5.5 NBR 70 Shore A Mean?

113 - Inside Diameter

The first value identifies the nominal inside diameter of the O-ring, which is 113 mm.

This dimension is essential when selecting the sealing ring for the shaft, housing or groove geometry.

5.5 - Cross-Section Diameter

The second value specifies the nominal circular cross-section diameter of 5.5 mm.

Cross-section diameter affects groove depth, sealing compression, groove fill and the available installation space.

NBR - Nitrile Butadiene Rubber

NBR stands for nitrile butadiene rubber, commonly known as nitrile rubber or Buna-N.

This elastomer is widely used for sealing applications involving mineral oils, many lubricating greases and selected industrial fluids.

70 Shore A - Elastomer Hardness

70 Shore A indicates the nominal hardness of the rubber compound on the Shore A scale.

This hardness is commonly used in general-purpose industrial sealing applications because it provides a balance between elastic deformation and mechanical resistance.

However, hardness alone does not determine the permissible operating pressure, temperature range or chemical compatibility.

Construction and Operating Principle

An O-ring is a continuous elastomeric ring with a circular cross-section.

When installed in a correctly designed sealing groove, the ring is compressed between the mating surfaces.

This initial deformation generates contact pressure, helping prevent the sealed medium from passing through the joint.

When fluid pressure is applied, the sealing contact pressure may increase further.

The effectiveness of the seal depends on several factors, including:

• Correct O-ring dimensions.

• Suitable groove geometry.

• Appropriate compression.

• Surface finish of mating components.

• Dimensional tolerances.

• Extrusion gap.

• Fluid compatibility.

• Operating temperature.

• Pressure and movement conditions.

A correctly selected O-ring must satisfy both dimensional and material requirements.

Properties of NBR 70 Shore A

Resistance to Mineral Oils and Greases

Nitrile rubber is widely used because of its generally good resistance to many mineral-based oils and industrial lubricating greases.

This makes NBR a common material for oil sealing, machinery components and hydraulic systems.

Actual compatibility depends on the oil formulation, additives, temperature and duration of exposure.

Elastic Deformation

NBR is an elastomer capable of deforming under installation compression.

This property allows the O-ring to conform to the mating surfaces and establish a sealing contact.

Maintaining suitable elasticity is important for long-term sealing performance.

Mechanical Properties

NBR compounds can provide useful mechanical strength and abrasion resistance.

These characteristics make nitrile rubber suitable for many industrial sealing applications, including certain dynamic arrangements.

However, not every NBR O-ring is suitable for continuous dynamic operation.

Material Limitations

Standard NBR is generally less resistant to prolonged ozone exposure, ultraviolet radiation and outdoor weathering than materials specifically designed for those conditions.

It may also be unsuitable for certain solvents, aggressive chemicals and high-temperature applications.

Chemical compatibility should always be verified for the actual operating medium.

Static Sealing Applications

O-ring NBR 113x5.5 mm 70 Shore A can be used in appropriately designed static sealing arrangements.

Typical static sealing applications include:

• Housing joints.

• Machine covers.

• Flanged connections.

• Industrial enclosures.

• Hydraulic components.

• Lubrication system connections.

• Mechanical assemblies requiring fluid retention.

In a static sealing arrangement, there is no intended relative movement between the O-ring and the mating sealing surfaces.

Correct groove design and compression are essential for maintaining sealing performance.

Dynamic Sealing Applications

NBR O-rings may also be used in selected dynamic sealing applications.

However, dynamic sealing requires additional consideration of:

• Type of movement.

• Sliding speed.

• Lubrication conditions.

• Friction.

• Operating temperature.

• Surface finish.

• O-ring twisting.

• Wear and extrusion risk.

An O-ring should not automatically be used as a replacement for a dedicated piston seal, rod seal or rotary shaft seal.

The suitability of the 113x5.5 mm size must be established from the mechanical design and operating conditions.

How to Select the Correct Groove for a 113x5.5 mm O-Ring

Correct groove design is just as important as selecting the correct O-ring dimensions.

Installation Diameter

Determine whether the O-ring is installed for internal or external sealing.

The installation arrangement affects the required circumferential stretch or compression.

Groove Depth

The groove depth must provide the appropriate compression of the 5.5 mm cross-section.

Insufficient compression may cause leakage.

Excessive compression can increase friction, accelerate material damage and reduce sealing performance.

Groove Width

The groove must provide sufficient space for the elastomer to deform.

Incorrect groove width can result in excessive groove filling.

Extrusion Gap

In pressurised applications, the clearance between mating components must be considered.

Excessive clearance may allow the elastomer to extrude into the gap.

Depending on the pressure and design, a backup ring may be necessary.

Dimensional Tolerances

O-ring tolerances, groove dimensions and component manufacturing tolerances must all be considered.

Universal groove dimensions should not be assigned solely from the nominal O-ring size of 113x5.5 mm.

NBR 70 Shore A vs Other O-Ring Materials

Material selection must be based on the actual operating medium, temperature, pressure and sealing arrangement.

Identical dimensions do not make O-rings manufactured from different elastomers automatically interchangeable.

Alternative Designations and Search References

Natural variations of the product designation include:

• O-Ring NBR 113x5.5 mm 70 Shore A

• NBR O-Ring 113x5.5

• O-Ring 113x5.5 NBR 70

• Nitrile Rubber O-Ring 113x5.5 mm

• Buna-N O-Ring 113x5.5 mm

• Oil-Resistant O-Ring 113x5.5 mm

• O-Ring ID 113 mm CS 5.5 mm

• NBR 70 Shore A Sealing Ring 113x5.5 mm

These are alternative written descriptions and search terms, not verified OEM part numbers or manufacturer cross-references.

Typical Industrial Applications

NBR 70 Shore A O-rings are commonly used in industrial sealing systems, including:

• Hydraulic assemblies using compatible fluids.

• Mineral oil lubrication systems.

• Industrial machinery housings.

• Flanged joints.

• Mechanical equipment.

• Industrial valves and fittings.

• Static sealing connections.

• Appropriately designed reciprocating sealing arrangements.

These are general applications of NBR O-rings rather than verified OEM applications for the specific 113x5.5 mm size.

The suitability of this O-ring for a particular machine must be established from the equipment specifications.

Installation and Maintenance

Clean the Sealing Surfaces

Before installation, clean the groove and all mating surfaces.

Remove dirt, metal particles and other contaminants that could damage the elastomer.

Check Edges and Surface Condition

Sharp edges, burrs and damaged surfaces can cut or tear the O-ring during installation.

Suitable edge preparation helps reduce the risk of mechanical damage.

Avoid Twisting

Install the O-ring evenly without twisting, excessive stretching or local pinching.

Twisting can cause uneven deformation and reduce sealing reliability.

Use Compatible Assembly Lubricants

Where permitted by the application, use a suitable assembly lubricant compatible with NBR and the sealed medium.

Do not use solvents or lubricants without checking chemical compatibility.

Verify Correct Installation

After assembly, check that the O-ring is correctly positioned and has not been displaced or trapped between components.

Carry out the required leakage or pressure test before placing the system into service.

Storage

Store elastomeric sealing rings away from excessive heat, direct sunlight, ozone sources and chemical contamination.

Appropriate storage helps preserve material properties before installation.

Frequently Asked Questions - O-Ring NBR 113x5.5 mm

What are the dimensions of the 113x5.5 mm O-ring?

The nominal inside diameter is 113 mm and the circular cross-section diameter is 5.5 mm. The calculated nominal outside diameter is 124 mm.

What does NBR 70 Shore A mean?

NBR identifies nitrile butadiene rubber, while 70 Shore A specifies the nominal hardness of the elastomer on the Shore A scale.

Is NBR 70 resistant to oil?

NBR generally offers good resistance to many mineral oils and lubricating greases. Compatibility must be checked for the specific fluid, additives and operating temperature.

Can the 113x5.5 mm O-ring be used in hydraulic systems?

Yes, it may be suitable for properly designed hydraulic sealing arrangements using compatible fluids. Groove geometry, pressure, temperature and extrusion clearance must be considered.

Can an NBR O-ring be used with water?

NBR may be suitable for certain water applications. However, prolonged exposure to water, especially at elevated temperatures, may require a different elastomer such as an appropriate EPDM compound.

Does 70 Shore A mean the O-ring can withstand high pressure?

No. Hardness is only one factor affecting sealing performance. Permissible pressure also depends on groove design, extrusion clearance, temperature and the use of backup rings.

Can NBR be replaced with FKM?

Not automatically. FKM may offer advantages in certain temperatures and chemical environments, but compatibility and mechanical requirements must be verified before substitution.

Is this O-ring suitable for dynamic sealing?

It may be suitable for selected dynamic applications when the sealing arrangement is correctly designed. Movement, speed, lubrication, friction and wear conditions must be evaluated.

O-Ring NBR 113x5.5 mm 70 Shore A - Key Technical Information

O-ring NBR 113x5.5 mm 70 Shore A is an elastomeric sealing ring with a 113 mm inside diameter and 5.5 mm circular cross-section. Manufactured from nitrile butadiene rubber, it offers generally good resistance to many mineral oils and lubricating greases. Correct selection requires consideration of fluid compatibility, operating temperature, pressure and groove geometry.

NBR O-Rings at simmering.pl

Simmering.pl supplies industrial O-rings, sealing rings and technical sealing solutions for machinery maintenance, engineering departments, industrial procurement and B2B customers.

Correct O-ring selection requires verification of the inside diameter, cross-section diameter, elastomer material and hardness.

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