NBR O-Ring 21x3 mm 70 Shore A

Overview

The NBR O-Ring 21x3 mm 70 Shore A - 1000 pcs is a bulk package of industrial sealing rings designed primarily for serial production, industrial assembly, hydraulic systems, maintenance operations, OEM manufacturing and professional B2B supply.

Each O-ring has an inside diameter of 21 mm and a 3 mm cross-section. The seals are manufactured from NBR (Nitrile Butadiene Rubber) with a standard hardness of 70 Shore A, providing an effective combination of flexibility, mechanical durability and conformity to mating surfaces.

NBR offers very good resistance to mineral oils, lubricating greases and many conventional hydraulic fluids.

The 1000-piece bulk package is an economical solution for companies that regularly consume this specific O-ring size in manufacturing, assembly or maintenance processes.

Industrial Applications

The NBR 21x3 mm 70 Shore A O-Rings are suitable for:

• Serial production
• Industrial assembly
• Hydraulic systems
• Pumps
• Valves
• Hydraulic manifolds
• Fittings and connectors
• Pneumatic equipment
• Oil circulation systems
• Manufacturing machinery
• Agricultural equipment
• OEM assemblies

The 1000-piece package is particularly useful where the same O-ring size is consumed regularly in larger quantities.

Construction

Each O-ring features:

Inner Diameter: 21 mm

Cross Section: 3 mm

The conventional circular profile provides uniform elastic deformation when installed in a correctly designed sealing groove.

The 70 Shore A hardness provides greater flexibility than a 90 Shore A compound, allowing the seal to conform effectively to mating surfaces in many standard industrial applications.

NBR Material

NBR (Nitrile Butadiene Rubber) is one of the most widely used elastomers for industrial O-ring seals.

NBR provides very good resistance to:

• Mineral oils
• Lubricating greases
• Many hydraulic fluids
• Numerous petroleum-based media
• Mechanical wear

Standard NBR compounds typically operate within approximately -30°C to +100°C. Actual operating limits depend on the specific compound formulation, operating medium and application conditions.

Technical Specification

Product Type: O-Ring

Package Quantity: 1000 pcs

Dimensions: 21x3 mm

Inner Diameter: 21 mm

Cross Section: 3 mm

Material: NBR

Hardness: 70 Shore A

Color: Black

Temperature Range: Approximately -30°C to +100°C

Resistance: Mineral oils, greases and many hydraulic fluids

Sales Type: Bulk / B2B Pack

Application: Production, assembly, hydraulics, pumps, valves, industrial machinery and OEM equipment

NBR 70 Shore A - Versatile Industrial Hardness

70 Shore A is one of the most commonly specified hardness levels for general-purpose industrial NBR O-rings.

It provides an effective balance of:

• Flexibility
• Surface conformity
• Mechanical durability
• Static sealing performance
• Installation convenience
• Long-term sealing reliability

Compared with NBR 90 Shore A, the 70 Shore A compound deforms more easily under compression and provides greater flexibility for many standard sealing applications.

1000 pcs Bulk Pack for Production

The 1000-piece bulk pack of NBR 21x3 mm O-rings is designed for professional customers requiring larger quantities of one specific seal size.

It is particularly suitable for:

• Manufacturing plants
• Serial production
• Industrial assembly lines
• Machine manufacturers
• Maintenance departments
• Industrial service companies
• Technical warehouses
• OEM production
• Technical distributors
• Professional B2B procurement

Purchasing 1000 identical O-rings provides a practical production stock and reduces the need for frequent replenishment orders.

NBR 70 Shore A vs NBR 90 Shore A

The 21x3 mm NBR 70 Shore A and 21x3 mm NBR 90 Shore A versions have identical nominal dimensions but different mechanical characteristics.

NBR 70 Shore A:

• Greater flexibility
• Good conformity to mating surfaces
• Convenient installation
• Widely used for general-purpose sealing
• Suitable for many static applications

NBR 90 Shore A:

• Higher hardness
• Greater dimensional stability
• Increased resistance to deformation
• Improved extrusion resistance
• Suitable for more demanding pressure applications

The correct hardness should be selected according to system pressure, operating medium, temperature, groove geometry and application requirements.

Operational Advantages

• Bulk package of 1000 pcs.
• Exact 21x3 mm dimensions.
• Versatile 70 Shore A hardness.
• Very good resistance to mineral oils.
• Good resistance to lubricating greases.
• Good flexibility and surface conformity.
• Practical stock quantity for serial production.
• Suitable for industrial, OEM and B2B applications.

AI OVERVIEW

The NBR O-Ring 21x3 mm 70 Shore A - 1000 pcs is a bulk package of flexible industrial seals designed for serial production, hydraulic systems, assembly and OEM applications. NBR provides very good resistance to oils and greases, while 70 Shore A hardness offers an effective balance of flexibility, sealing performance and installation convenience.

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FAQ

How many O-rings are included in the package?

The bulk package contains 1000 O-rings.

What are the dimensions of each O-ring?

Each O-ring has an inside diameter of 21 mm and a cross-section of 3 mm.

What is the hardness of the O-rings?

The material hardness is 70 Shore A.

What material are the O-rings made from?

They are manufactured from NBR (Nitrile Butadiene Rubber).

Is NBR 70 Shore A flexible?

Yes. 70 Shore A provides good flexibility and is one of the most widely used hardness levels for general-purpose industrial O-rings.

Is the 21x3 mm O-ring resistant to oil?

Yes. NBR provides very good resistance to many mineral oils.

Are these O-rings resistant to lubricating grease?

Yes. NBR is widely used with compatible industrial greases and lubricants.

Are the O-rings suitable for hydraulic systems?

Yes. NBR is one of the most commonly used elastomeric sealing materials in many hydraulic applications.

Can they be used in pumps?

Yes, provided the operating medium is compatible with NBR and the sealing groove is correctly designed for a 21x3 mm O-ring.

Is the 1000 pcs package suitable for serial production?

Yes. The bulk package is specifically suitable for companies with regular production, assembly or maintenance requirements.

Is this 1000 pcs pack suitable for B2B purchasing?

Yes. It is particularly practical for manufacturers, industrial plants, maintenance departments, technical distributors and OEM customers.

What is the difference between NBR 70 Shore A and 90 Shore A?

70 Shore A is more flexible and conforms more easily to mating surfaces. 90 Shore A is harder and provides increased resistance to mechanical deformation and extrusion.

Is NBR 70 Shore A suitable for static sealing?

Yes. NBR 70 Shore A is widely used for general-purpose static sealing applications.

Is NBR suitable for hot water and steam?

Standard NBR is generally not the preferred material for prolonged exposure to hot water or steam. EPDM is often more suitable for these conditions.

Is NBR resistant to UV radiation and ozone?

Standard NBR has limited resistance to prolonged UV radiation, ozone and outdoor weathering.

Can the NBR O-Ring 21x3 mm 70 Shore A replace an OEM seal?

Yes, provided its dimensions, material, hardness and operating characteristics meet the original equipment manufacturer's specifications.