O-ring 85x5 NBR 70 Shore A

Characteristics of O-ring 85x5 mm NBR 70 Shore A

The O-ring 85x5 mm is a continuous elastomeric ring with a circular cross-section. Its primary function is to prevent or limit the leakage of liquids or gases between mating components.

Sealing is achieved through controlled compression of the elastomer within a properly designed installation groove.

Key product characteristics:

• Inside diameter: 85 mm.

• Cross-sectional diameter: 5 mm.

• Material: NBR (nitrile butadiene rubber).

• Nominal hardness: 70 Shore A.

• Calculated nominal outside diameter: 95 mm.

• Construction: Continuous ring with a circular cross-section.

• Sealing type: Elastomeric O-ring.

• Applications: Static and appropriately designed dynamic sealing systems.

NBR is widely used in industrial sealing applications involving compatible oils, greases and other technical fluids.

Technical Specifications

Calculated Outside Diameter

The nominal outside diameter of an O-ring in its free, uncompressed state is calculated using the following formula:

For O-ring 85x5 mm:

The calculated nominal outside diameter is 95 mm.

This value is based on the nominal geometric dimensions and does not represent a separately verified manufacturing tolerance.

What Does O-ring 85x5 mm NBR 70 Shore A Mean?

85 mm - Inside Diameter

The value of 85 mm specifies the nominal inside diameter of the O-ring in its free, uncompressed condition.

This dimension is essential when selecting an O-ring for a particular sealing groove or mechanical assembly.

Depending on the installation arrangement, the O-ring may require controlled stretching during assembly.

Excessive stretching can reduce the cross-sectional diameter and affect sealing performance.

5 mm - Cross-Sectional Diameter

The cross-sectional diameter of 5 mm defines the nominal thickness of the elastomeric ring.

This dimension influences:

• Initial sealing compression.

• Groove fill.

• Contact pressure.

• Available elastomer deformation.

• Resistance to extrusion into the clearance gap.

• Suitability for the intended sealing arrangement.

A 5 mm cross-section does not mean that the installation groove should be exactly 5 mm deep.

The correct groove depth depends on the required compression and the specific sealing design.

NBR - Nitrile Butadiene Rubber

NBR is a synthetic elastomer commonly used in industrial sealing technology.

Its relevant properties include:

• Resistance to many mineral-based oils.

• Compatibility with numerous industrial lubricating greases.

• Elasticity suitable for compression sealing.

• Wear resistance under appropriate operating conditions.

• Suitability for many conventional mechanical sealing applications.

Chemical resistance depends on the specific NBR compound, the type of medium, operating temperature and exposure time.

NBR should not automatically be considered compatible with every synthetic oil, fuel, solvent or chemical substance.

70 Shore A - Elastomer Hardness

The designation 70 Shore A identifies the nominal hardness of the elastomer according to the Shore A hardness scale.

Hardness influences the material's resistance to deformation, the required sealing compression and its behaviour under mechanical loading.

An O-ring with a nominal hardness of 70 Shore A can be used in many conventional sealing arrangements.

However, hardness alone does not determine the maximum permissible operating pressure.

Pressure resistance also depends on groove geometry, extrusion clearance, temperature and the characteristics of the specific elastomer compound.

Construction and Operating Principle

O-ring 85x5 mm NBR 70 Shore A is a one-piece elastomeric sealing element with a circular cross-section.

When installed in a properly designed groove, the O-ring is compressed between mating surfaces.

This compression generates contact pressure that limits the passage of the sealed medium through the connection.

In appropriately designed systems, fluid pressure may additionally support the sealing action.

Sealing performance depends on:

• Correct inside diameter.

• Appropriate groove depth and width.

• Required compression ratio.

• Groove fill.

• Clearance between mating components.

• Surface finish.

• Compatibility between NBR and the sealed medium.

• Operating temperature and pressure.

• Movement and lubrication conditions.

Incorrect groove geometry may result in leakage, excessive deformation or premature O-ring damage.

NBR 70 Shore A vs FKM 70 Shore A and EPDM 70 Shore A

O-rings with identical dimensions and nominal hardness may have different chemical and operating characteristics.

These are general material characteristics, not guaranteed specifications for an individual elastomer compound.

NBR, FKM and EPDM O-rings are not automatically interchangeable, even when their dimensions are 85x5 mm and their nominal hardness is 70 Shore A.

Applications of O-ring 85x5 mm NBR 70 Shore A

NBR O-rings with dimensions of 85x5 mm may be used in appropriately designed sealing arrangements involving:

• Mechanical covers and housings.

• Static sealing connections.

• Selected hydraulic components.

• Selected pneumatic assemblies.

• Technical fittings and connectors.

• Industrial machinery.

• Selected oil-lubricated mechanical assemblies.

These are general application categories for NBR O-rings, not a verified list of equipment requiring the exact 85x5 mm size.

Static Sealing Applications

In static sealing arrangements, the O-ring is installed between components that do not move relative to one another during normal operation.

Correct compression maintains contact between the elastomer and the mating surfaces.

Typical static sealing arrangements include appropriately designed covers, housings and mechanical connections.

Dynamic Sealing Applications

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

However, dynamic sealing requires additional consideration of:

• Friction.

• Lubrication.

• Movement speed.

• Wear.

• Operating pressure.

• Groove geometry.

• Surface finish.

• Extrusion clearance.

The dimensions 85x5 mm and nominal hardness of 70 Shore A do not independently confirm suitability for a specific dynamic application.

Selection and Interchangeability

Before purchasing O-ring 85x5 mm NBR 70 Shore A, verify:

1. Inside diameter: 85 mm.

2. Cross-sectional diameter: 5 mm.

3. Sealing material: NBR.

4. Nominal hardness: 70 Shore A.

5. Installation groove dimensions.

6. Required compression and installation stretch.

7. Type of sealed medium.

8. Operating temperature and pressure.

9. Static or dynamic sealing requirements.

10. Required dimensional tolerances and material specifications.

Can an 85x5 mm O-ring Be Replaced with Another Size?

Interchangeability should not be assumed for O-rings with similar dimensions, such as 84x5 mm, 85x4 mm or 85x5.3 mm.

Differences in inside diameter and cross-section influence installation stretch, compression and groove fill.

A replacement must satisfy the dimensional and material requirements of the original sealing arrangement.

Installation Recommendations

Before installation, clean the sealing groove and mating surfaces thoroughly.

Inspect the O-ring for cuts, cracks, contamination and permanent deformation.

During installation:

• Avoid sharp edges and burrs.

• Do not twist the O-ring.

• Avoid excessive stretching.

• Use an installation lubricant compatible with NBR and the sealed medium when required.

• Ensure correct positioning in the groove.

• Prevent pinching during assembly.

Correct installation helps reduce the risk of premature damage and leakage.

Storage

Store unused NBR O-rings in a clean, dry environment away from direct sunlight, excessive heat, ozone and chemicals that may affect elastomer properties.

Avoid prolonged stretching or deformation during storage.

Alternative Designations and Reference Names

The product may also be identified using the following descriptions:

• O-ring 85x5 mm NBR 70 Shore A

• O-ring NBR 85x5 mm

• NBR O-ring 85x5 mm 70 Shore A

• Nitrile rubber O-ring 85x5 mm

• Rubber sealing ring 85x5 NBR

• O-ring 85 mm ID 5 mm CS

• O-ring NBR 70 85x5 mm

• Industrial O-ring 85x5 mm

These are alternative descriptive designations, not additional manufacturer part numbers or confirmed OEM references.

No unverified OEM number, EAN or dimensional tolerance class has been assigned to this product.

FAQ - O-ring 85x5 mm NBR 70 Shore A

1. What are the dimensions of O-ring 85x5 mm?

The O-ring has an inside diameter of 85 mm and a cross-sectional diameter of 5 mm. Its calculated nominal outside diameter in the free state is 95 mm.

2. What does NBR 70 Shore A mean?

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

3. Is NBR 70 Shore A resistant to oil?

NBR is resistant to many mineral-based oils and lubricating greases. Compatibility with a specific lubricant must be verified individually.

4. Is O-ring 85x5 mm suitable for hydraulic applications?

It may be suitable for appropriately designed hydraulic systems using compatible fluids. Operating pressure, temperature, groove geometry and extrusion clearance must be checked.

5. Can an 85x5 mm O-ring be replaced with an 85x4 mm O-ring?

Not without technical verification. Reducing the cross-sectional diameter from 5 mm to 4 mm significantly changes compression and groove fill.

6. Can NBR 70 Shore A be replaced with FKM 70 Shore A?

Not automatically. Although the nominal hardness is identical, the materials differ in chemical resistance and operating characteristics.

7. Does 85x5 mm indicate the outside diameter?

No. The first value identifies the inside diameter, while the second specifies the cross-sectional diameter. The calculated nominal outside diameter is 95 mm.

8. How should the groove for an 85x5 mm NBR O-ring be selected?

Groove dimensions must account for the sealing arrangement, required compression, groove fill, extrusion clearance and operating conditions. The O-ring dimensions alone are insufficient to define a universal groove geometry.

O-ring 85x5 mm NBR 70 Shore A - Key Technical Information

O-ring 85x5 mm NBR 70 Shore A is an elastomeric sealing ring with an inside diameter of 85 mm and a circular cross-section of 5 mm. Manufactured from nitrile butadiene rubber with a nominal hardness of 70 Shore A, it is intended for appropriately engineered sealing applications. Its calculated nominal outside diameter is 95 mm. Selection requires verification of media compatibility, groove geometry and operating conditions.

O-ring 85x5 mm NBR 70 Shore A is available from simmering.pl, a specialist supplier of industrial sealing products, O-rings, rotary shaft seals and rolling bearings.

With warehouse operations in Lublin, Poland, simmering.pl supplies industrial customers, maintenance departments and international B2B buyers, with worldwide shipping options.