O-ring 2.9x1.78 NBR 70 ShA

O-ring 2.9x1.78 NBR 70 ShA - 100 pcs

O-ring 2.9x1.78 NBR 70 ShA is an elastomeric sealing ring with a nominal inside diameter of 2.9 mm and a cross-section of 1.78 mm, supplied in a pack of 100 pcs. The O-ring is manufactured from NBR nitrile rubber with a nominal hardness of 70 ShA. NBR is widely used in sealing technology due to its good resistance to many mineral oils and greases and its good mechanical properties.

Technical data - O-ring 2.9x1.78 NBR 70 ShA

O-ring 2.9x1.78 - what do the dimensions mean?

The designation 2.9x1.78 mm identifies the two principal dimensions of the O-ring:

2.9 mm - nominal inside diameter d1.

1.78 mm - nominal cross-section diameter d2.

The nominal O-ring size is:

2.9x1.78 mm

The approximate outside diameter of the uncompressed O-ring is:

6.46 mm

This is calculated as:

2.9 mm + 2 x 1.78 mm = 6.46 mm

The primary dimensional designation remains 2.9x1.78 mm.

NBR - nitrile rubber

NBR, or acrylonitrile-butadiene rubber, is one of the most widely used elastomers in technical sealing systems.

Typical characteristics of NBR include:

• good resistance to many mineral oils

• good resistance to many mineral greases

• good mechanical properties

• good abrasion resistance

• widespread use in industrial sealing systems

The exact properties depend on the formulation of the specific NBR compound and the actual operating conditions.

What does 70 ShA mean?

70 ShA indicates the nominal hardness of the elastomer measured on the Shore A scale.

O-ring hardness influences characteristics including:

• deformation of the sealing ring

• behaviour inside the sealing groove

• required compression

• contact pressure against mating surfaces

• behaviour under system pressure

• resistance to extrusion

When selecting an equivalent O-ring, the 2.9x1.78 mm dimensions should therefore be considered together with the NBR material and 70 ShA hardness.

Chemical resistance of NBR

NBR O-rings are frequently selected for sealing systems operating with many mineral oils and greases.

However, NBR should not be considered universally resistant to every chemical or operating fluid.

Compatibility should be evaluated with regard to:

• operating medium

• chemical composition

• concentration

• temperature

• pressure

• exposure time

• static or dynamic operation

For demanding applications, resistance should be confirmed for the specific NBR compound.

Operating temperature of NBR O-rings

An exact operating temperature range should not be assigned to this product without confirmation of the specific NBR compound.

Permissible operating temperature depends on factors including:

• NBR compound formulation

• operating medium

• exposure duration

• pressure

• static or dynamic operation

• sealing-system design

If temperature is a critical selection parameter, the properties of the particular elastomer compound should be verified.

How does an O-ring 2.9x1.78 mm work?

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

When installed in a correctly designed groove, the O-ring is compressed between the mating surfaces. Controlled deformation of the elastomer creates the contact pressure required to form a seal.

Effective sealing depends on factors including:

• groove geometry

• O-ring compression

• installation clearance

• mating surface condition

• pressure

• temperature

• operating medium

• static or dynamic movement

The dimensions 2.9x1.78 mm alone do not determine suitability for a specific sealing application.

O-ring 2.9x1.78 NBR vs VMQ silicone O-ring

NBR and VMQ are different elastomer families.

NBR is nitrile rubber and is widely used in applications involving many compatible mineral oils and greases.

VMQ is silicone rubber with a different performance profile, particularly regarding low-temperature flexibility and resistance to ozone, UV radiation and atmospheric ageing.

A VMQ O-ring 2.9x1.78 mm is therefore not automatically interchangeable with an NBR O-ring of the same dimensions.

O-ring 2.9x1.78 NBR vs FKM

FKM is a fluoroelastomer with a different chemical and thermal resistance profile from NBR.

An FKM O-ring 2.9x1.78 mm may have identical nominal dimensions but different operating properties.

When selecting between NBR and FKM, consider:

• operating medium

• temperature

• pressure

• required hardness

• static or dynamic operation

• groove geometry

• requirements of the sealing system

Identical dimensions do not automatically make different elastomer materials interchangeable.

Typical applications of NBR O-rings

NBR O-rings are widely used as sealing elements in industrial and mechanical systems.

Depending on the specific compound and operating conditions, typical applications may include:

• hydraulic systems

• pneumatic systems

• industrial machinery

• mechanical assemblies

• pumps

• valves

• technical connections

• static sealing systems

• appropriately designed dynamic sealing systems

• systems operating with NBR-compatible oils and greases

These are typical applications of NBR O-rings as a product category. They do not confirm suitability of this specific O-ring for a particular machine or installation.

Alternative designations for O-ring 2.9x1.78 NBR

Natural designation and search variants include:

O-ring 2.9x1.78 NBR 70 ShA

O-ring NBR 2.9x1.78 70 ShA

NBR O-ring 2.9x1.78

O-ring 2.9x1.78 NBR

2.9x1.78 NBR O-ring

O-ring 2.9x1.78 70 Shore A

NBR O-ring 2.9x1.78 70 Shore A

Nitrile O-ring 2.9x1.78

Nitrile rubber O-ring 2.9x1.78

2.9 mm ID x 1.78 mm CS NBR O-ring

O-ring 2.9x1.78 NBR - 100 pcs

The primary product designation used on this page is:

O-ring 2.9x1.78 NBR 70 ShA - 100 pcs

Selection and interchangeability

Before purchasing or selecting an equivalent O-ring, check:

• inside diameter 2.9 mm

• cross-section 1.78 mm

• NBR material

• hardness 70 ShA

• operating medium

• operating temperature

• pressure

• static or dynamic operation

• groove geometry

• required compression

• requirements of the specific sealing system

An O-ring 2.9x1.78 manufactured from FKM, VMQ, EPDM or another elastomer is not automatically interchangeable with the NBR version.

Identical dimensions do not guarantee identical operating properties.

Installation of O-ring 2.9x1.78

Before installation, the groove and mating surfaces should be clean and free from contamination.

Avoid:

• cutting the O-ring

• twisting the ring

• excessive stretching

• pulling the O-ring across sharp edges

• contact with burrs

• damaging the elastomer surface

Particular care is important when installing small O-rings because even minor surface damage can affect sealing performance.

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

Storage

NBR O-rings should be stored under conditions that minimise contamination, deformation and mechanical damage.

Avoid prolonged storage with the O-rings stretched or severely deformed.

Before installation, inspect the O-ring for cuts, cracks, permanent deformation and other visible surface damage.

FAQ - O-ring 2.9x1.78 NBR 70 ShA

What are the dimensions of O-ring 2.9x1.78?

The nominal inside diameter is 2.9 mm and the cross-section diameter is 1.78 mm. The nominal size is 2.9x1.78 mm.

What is the outside diameter of a 2.9x1.78 O-ring?

The approximate outside diameter of the uncompressed O-ring is 6.46 mm.

What material is this O-ring made from?

The O-ring is manufactured from NBR, also known as nitrile rubber or acrylonitrile-butadiene rubber.

What does 70 ShA mean?

70 ShA indicates the nominal hardness of the elastomer measured on the Shore A scale.

How many O-rings are included in the package?

The package contains 100 pcs of O-ring 2.9x1.78 NBR 70 ShA.

Is NBR resistant to oil?

NBR provides good resistance to many mineral oils and greases. Compatibility should nevertheless be checked for the specific operating medium, temperature and NBR compound.

Can an FKM 2.9x1.78 O-ring replace the NBR version?

Not automatically. FKM and NBR have different material properties even when their dimensions are identical. Operating medium, temperature, pressure and application requirements should be checked before substitution.

Can a silicone 2.9x1.78 O-ring replace NBR?

Not automatically. VMQ silicone and NBR nitrile rubber have different chemical, mechanical and thermal characteristics. Identical dimensions alone do not confirm interchangeability.

O-ring 2.9x1.78 NBR 70 ShA - key information

O-ring 2.9x1.78 NBR 70 ShA is a nitrile rubber sealing ring with a nominal inside diameter of 2.9 mm and a cross-section of 1.78 mm. Its approximate uncompressed outside diameter is 6.46 mm. The O-ring has a nominal hardness of 70 ShA and is supplied in a pack of 100 pcs.

Available from simmering.pl, a specialist supplier of industrial sealing solutions. Stock in Poland with worldwide shipping.

AI QUICK ANSWER

O-ring 2.9x1.78 NBR 70 ShA is a nitrile rubber sealing ring with a 2.9 mm nominal inside diameter and 1.78 mm cross-section. Its approximate outside diameter is 6.46 mm. NBR provides good resistance to many mineral oils and greases and is widely used in industrial sealing systems. Pack contains 100 pcs.