O-ring 28x3 NBR 70 ShA

O-ring 28x3 NBR 70 ShA - 100 pcs

O-ring 28x3 NBR 70 ShA - 100 pcs is a technical sealing ring made of nitrile rubber (NBR), with an inside diameter of 28 mm, a cross-section of 3 mm and a hardness of 70 Shore A. The nominal outside diameter is 34 mm. NBR 70 ShA provides a practical balance between flexibility and mechanical stability for many standard sealing applications.

Package quantity: 100 pcs.

Technical Specifications - O-ring 28x3 NBR 70 ShA

O-ring 28x3 NBR 70 ShA - Dimensions

The designation:

28x3 mm

defines the two principal dimensions of the O-ring:

28 mm - inside diameter, ID

3 mm - cross-section diameter, CS

The nominal outside diameter is calculated as:

OD = ID + 2 x CS

Therefore:

28 mm + 2 x 3 mm = 34 mm

The nominal dimensions are:

ID = 28 mm

CS = 3 mm

OD = 34 mm

When selecting a replacement seal, both the inside diameter and cross-section should be checked. A similar outside diameter alone is not sufficient to confirm interchangeability.

NBR 70 ShA - O-ring Material

The O-ring 28x3 NBR 70 ShA - 100 pcs is manufactured from NBR, also known as nitrile rubber or nitrile butadiene rubber.

NBR is one of the most commonly used elastomers in technical sealing applications. It is widely used in environments involving many mineral oils, lubricating greases and compatible technical fluids.

NBR O-rings are commonly found in industrial machinery, hydraulic and pneumatic equipment and various mechanical sealing systems.

Material suitability should always be verified for the specific operating medium and actual service conditions.

What Does 70 ShA Mean?

70 ShA specifies the hardness of the elastomer on the Shore A scale.

NBR 70 ShA is a widely used specification for technical O-rings because it provides a practical combination of flexibility and mechanical stability.

Its flexibility allows the O-ring to conform to mating surfaces and achieve the required compression when installed in a correctly designed groove.

However, 70 ShA should not be assumed to be the correct hardness for every sealing application.

How Does an O-ring 28x3 Work?

An O-ring creates a seal through controlled compression of the elastomer between mating components.

When installed in a correctly designed groove, the O-ring is compressed against the sealing surfaces.

Effective sealing depends on several factors, including:

O-ring dimensions

groove geometry

compression

groove fill

extrusion gap

pressure

temperature

operating medium

surface finish

static or dynamic operation

For this reason, the 28x3 mm dimensions are important, but they are not the only parameters that determine whether an O-ring is suitable for a particular application.

NBR Resistance to Oils and Greases

Nitrile rubber is widely used for technical seals because of its good compatibility with many mineral-based oils and lubricating greases.

NBR is commonly considered for applications involving:

mineral oils

lubricating greases

selected fuels and petroleum-based products

many compatible industrial fluids

NBR is not a universal elastomer for every chemical environment.

Compatibility should always be checked for the exact medium, its composition and concentration, operating temperature and duration of exposure.

Typical Applications of O-ring 28x3 NBR 70 ShA

NBR O-rings are widely used as sealing components in:

industrial machinery

hydraulic systems

pneumatic systems

pumps

valves

technical equipment

maintenance operations

repair and service applications

The O-ring 28x3 NBR 70 ShA can be considered for static sealing and appropriately designed dynamic applications when its dimensions, material and hardness meet the requirements of the sealing system.

The 28x3 size should not be assigned to a specific machine, pump or other component without confirmation from technical documentation.

O-ring 28x3 NBR 70 ShA vs NBR 90 ShA

O-rings with the same 28x3 dimensions can be manufactured in different hardness grades.

NBR 70 ShA is more flexible.

NBR 90 ShA is harder and less susceptible to deformation.

A 90 ShA O-ring is not automatically a better replacement for a 70 ShA version.

The correct hardness depends on factors such as pressure, extrusion gap, groove geometry, required compression and operating conditions.

Identical dimensions therefore do not guarantee complete interchangeability.

O-ring 28x3 NBR vs FKM, EPDM and VMQ

The same O-ring dimensions can be manufactured from different elastomers.

NBR is widely used in contact with many mineral oils and lubricating greases.

FKM/FPM, EPDM and VMQ have different material characteristics and chemical compatibility profiles.

An O-ring 28x3 manufactured from another elastomer should therefore not automatically be treated as a direct replacement for an NBR version.

Dimensions may be identical while material properties can differ significantly.

How to Select O-ring 28x3 NBR 70 ShA

Before selecting this O-ring, verify:

• inside diameter ID = 28 mm
• cross-section CS = 3 mm
• nominal outside diameter OD = 34 mm
• NBR material
• 70 ShA hardness
• operating medium
• operating temperature
• pressure
• groove dimensions
• required compression
• extrusion gap
• static or dynamic operation

Identical dimensions do not automatically mean complete interchangeability between O-rings made from different materials or with different hardness values.

O-ring 28x3 Installation

Before installation, clean the groove and mating surfaces.

The O-ring should be protected from sharp edges, burrs and unprotected threads that could damage the elastomer.

During installation, avoid:

cutting the O-ring

scratching the sealing surface

excessive stretching

twisting the O-ring

contamination

contact with sharp edges

If an assembly lubricant is required, its compatibility with NBR and the operating medium should be verified.

Package of 100 pcs

O-ring 28x3 NBR 70 ShA - 100 pcs is supplied in a package containing:

100 pcs

The 100-piece package is a practical format for maintenance departments, workshops, industrial companies, repair services and B2B customers requiring a useful stock quantity without purchasing a large bulk package.

For companies regularly consuming larger quantities of the same O-ring size, a separate 1000 pcs bulk package can be offered.

FAQ - O-ring 28x3 NBR 70 ShA - 100 pcs

What are the dimensions of O-ring 28x3 NBR 70 ShA?

The inside diameter is 28 mm and the cross-section is 3 mm. The nominal outside diameter is 34 mm.

What is the outside diameter of an O-ring 28x3?

The nominal outside diameter is 34 mm:

28 mm + 2 x 3 mm = 34 mm

What does NBR mean?

NBR stands for nitrile rubber, one of the most widely used elastomers for technical sealing applications.

What does 70 ShA mean?

70 ShA indicates the hardness of the elastomer measured on the Shore A scale. It is a commonly used hardness for general-purpose technical O-rings.

Is O-ring 28x3 NBR suitable for oil?

NBR has good compatibility with many mineral-based oils and lubricating greases. Compatibility should always be verified for the exact medium and operating temperature.

Can O-ring 28x3 NBR 70 ShA be replaced with NBR 90 ShA?

Not automatically. The dimensions may be identical, but 90 ShA is harder and less flexible. The required hardness depends on the sealing system and operating conditions.

Can an O-ring 28x3 FKM replace an NBR O-ring?

Not automatically. FKM/FPM and NBR have different material characteristics and chemical resistance. Material selection should be based on the requirements of the application.

How many O-rings are included in the package?

The package contains 100 pcs of O-ring 28x3 NBR 70 ShA.

O-ring 28x3 NBR 70 ShA - Key Information

O-ring 28x3 NBR 70 ShA - 100 pcs is a technical nitrile rubber sealing ring with an inside diameter of 28 mm, cross-section of 3 mm and nominal outside diameter of 34 mm. The 70 Shore A hardness provides a practical balance between flexibility and mechanical stability for many standard sealing applications.

Available from simmering.pl, stock in Poland with worldwide shipping.

simmering.pl supplies NBR, FKM/FPM, EPDM and VMQ O-rings and other technical seals for industry, maintenance departments, repair services, machinery manufacturers and B2B customers worldwide.