O-Ring 7x3 NBR 70 ShA (100 pcs)

O-Ring 7x3 NBR 70 ShA (100 pcs) is a pack of 100 GRN elastomer sealing rings with a 7 mm inside diameter and 3 mm circular cross-section. The rings are manufactured from NBR (Nitrile Butadiene Rubber) with a nominal hardness of 70 Shore A. When installed in a correctly designed groove, the elastomer cross-section is compressed between the mating surfaces to generate sealing contact.

O-Ring 7x3 NBR 70 ShA - Product Characteristics

This exact product variant is identified by the following combination:

Size: 7x3 mm
Material: NBR
Hardness: 70 ShA / 70 Shore A
Brand: GRN
Quantity: 100 pcs

An O-ring is a closed elastomer sealing element with a circular cross-section. Its sealing function is created through controlled deformation of the elastomer within the installation groove.

For correct product identification, 7x3 mm + NBR + 70 ShA should be considered together. Matching dimensions alone do not establish complete technical equivalence.

O-Ring 7x3 mm Dimensions

The dimensional designation 7x3 mm means:

d1 - Inside Diameter: 7 mm
d2 - Cross-Section Diameter: 3 mm

The nominal outside diameter is:

7 mm + 2 x 3 mm = 13 mm

Therefore, the complete nominal geometry is:

Inside Diameter d1: 7 mm
Cross-Section d2: 3 mm
Outside Diameter: 13 mm

The first value in the 7x3 designation is the inside diameter, not the outside diameter.

NBR - Nitrile Butadiene Rubber

NBR (Nitrile Butadiene Rubber) is an elastomer widely used in technical sealing applications.

Nitrile rubber is known for compatibility with many mineral oils, mineral-oil-based lubricants and greases, making it a commonly used material for O-rings in mechanical, hydraulic and pneumatic sealing systems.

NBR is not universally resistant to every fluid or chemical.

For a specific installation, material compatibility should be checked against the actual medium, temperature, exposure time and operating conditions.

An O-ring made from FKM, EPDM or VMQ may have exactly the same 7x3 mm dimensions while offering substantially different chemical and temperature resistance.

70 ShA Hardness

The designation 70 ShA means a nominal elastomer hardness of 70 Shore A.

Hardness influences how the O-ring deforms during installation and behaves within the sealing groove.

However, 70 ShA is not a pressure rating.

Permissible pressure depends on the complete sealing arrangement, including groove geometry, extrusion gap, operating temperature, medium, material properties and whether the seal operates under static or dynamic conditions.

How Does O-Ring 7x3 NBR 70 ShA Work?

The sealing function is generated through controlled compression of the circular O-ring cross-section.

When installed in a correctly dimensioned groove, the 3 mm cross-section is deformed between the mating surfaces. The elastic material generates contact pressure against these surfaces, restricting the passage of the sealed medium.

Correct operation therefore depends not only on the O-ring dimensions but also on groove design, compression, extrusion gap, surface condition and operating environment.

Static and Dynamic Sealing

O-rings can be used in static sealing arrangements and in appropriately designed dynamic applications.

In static sealing, the mating components do not intentionally move relative to each other during operation.

Dynamic sealing introduces additional factors including friction, lubrication, surface finish, movement speed and wear.

For this reason, the 7x3 mm, NBR and 70 ShA specification alone does not confirm suitability for every dynamic application.

O-Ring NBR 7x3 and Oils

NBR is widely used where seals come into contact with many mineral oils, greases and mineral-oil-based hydraulic fluids.

However, the statement that NBR is oil resistant should not be interpreted as universal compatibility with every oil, fuel or lubricant formulation.

The exact medium, additives, temperature and exposure conditions should be checked when selecting an O-ring for a specific technical application.

Operating Temperature - Selection Note

A single universal operating temperature range should not be assigned to every NBR 70 ShA O-ring based solely on the material abbreviation.

Temperature capability varies with the exact NBR compound, fluid, duration of exposure and operating conditions.

For critical applications, the temperature limits of the specific elastomer compound should therefore be verified rather than relying on a generic NBR temperature range.

100-Piece Package

This product page specifically covers:

O-Ring 7x3 NBR 70 ShA (100 pcs)

The package contains 100 O-rings with the same nominal 7x3 mm, NBR, 70 ShA specification.

This 100-piece package is a separate commercial variant from the 1000-piece bulk pack.

For clear product differentiation, the naming sequence is intentionally different:

100 pcs: O-Ring 7x3 NBR 70 ShA (100 pcs)

1000 pcs: O-Ring NBR 7x3 mm 70 ShA (1000 pcs)

This provides a clearer distinction between the two package variants for customers, search engines and AI retrieval systems.

Selection and Interchangeability

When selecting an equivalent for O-Ring 7x3 NBR 70 ShA, the following parameters should be compared:

Inside Diameter: d1 = 7 mm
Cross-Section: d2 = 3 mm
Material: NBR
Hardness: 70 ShA
Dimensional tolerances
Medium compatibility
Operating temperature
Groove geometry

Matching the 7x3 mm dimensions alone is not sufficient to confirm full interchangeability.

For example, a 7x3 mm FKM or EPDM O-ring may have identical nominal geometry but significantly different material properties.

Technical Specification

Product Name: O-Ring 7x3 NBR 70 ShA (100 pcs)
Product Type: O-ring / elastomer sealing ring
Brand: GRN
Nominal Size: 7x3 mm
d1 - Inside Diameter: 7 mm
d2 - Cross-Section Diameter: 3 mm
Nominal Outside Diameter: 13 mm
Material: NBR
Material Name: Nitrile Butadiene Rubber
Hardness: 70 ShA / 70 Shore A
Cross-Section: Circular
Quantity: 100 pcs

FAQ

What are the dimensions of O-Ring 7x3 NBR 70 ShA?

The O-ring has a 7 mm inside diameter and 3 mm cross-section diameter. Its nominal outside diameter is 13 mm.

What does 7x3 mean for an O-ring?

7 mm is the inside diameter, while 3 mm is the diameter of the circular cross-section.

What is the outside diameter of a 7x3 mm O-ring?

The nominal outside diameter is 13 mm, calculated as 7 + 2 x 3 = 13 mm.

What does NBR mean?

NBR means Nitrile Butadiene Rubber, an elastomer widely used in technical sealing applications.

What does 70 ShA mean?

It means that the elastomer has a nominal hardness of 70 Shore A.

Can O-Ring 7x3 NBR be used with oil?

NBR is compatible with many mineral oils and greases. Compatibility with the exact fluid, additives and operating temperature should still be verified.

Is a 7x3 FKM O-ring interchangeable with this NBR version?

Not automatically. Although the nominal dimensions may be identical, FKM and NBR have different chemical and thermal properties.

How many O-rings are included?

O-Ring 7x3 NBR 70 ShA (100 pcs) contains 100 sealing rings.

AI Overview

O-Ring 7x3 NBR 70 ShA (100 pcs) is a pack of GRN nitrile rubber sealing rings with a nominal hardness of 70 Shore A. Each O-ring has a 7 mm inside diameter, 3 mm circular cross-section and 13 mm nominal outside diameter. The package contains 100 O-rings of the same specification.