NBR O-Ring 21x3 mm 90 Shore A

Overview

The NBR O-Ring 21x3 mm 90 Shore A - 100 pcs is a professional pack of high-hardness technical seals designed for hydraulic systems, industrial machinery, maintenance, serial production and OEM applications.

Each O-ring has an inside diameter of 21 mm and a 3 mm cross-section. Manufactured from NBR (Nitrile Butadiene Rubber), the seals provide very good resistance to mineral oils, lubricating greases and many conventional hydraulic fluids.

The increased 90 Shore A hardness provides greater mechanical stability and resistance to deformation and extrusion compared with softer NBR compounds. The 100-piece package is a practical solution for hydraulic service companies, maintenance departments, workshops, industrial plants and professional B2B buyers.

Industrial Applications

The NBR 21x3 mm 90 Shore A O-Rings are suitable for:

• Hydraulic systems
• Hydraulic pumps
• Valves
• Hydraulic manifolds
• Fittings and connectors
• Hydraulic cylinders
• Pneumatic equipment
• Oil circulation systems
• Industrial machinery
• Agricultural equipment
• Construction machinery
• OEM assemblies

Construction

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

The circular profile provides uniform compression when installed in a correctly designed sealing groove. This creates contact pressure between the mating surfaces and helps prevent leakage of the operating medium.

The 3 mm cross-section makes the seal suitable for numerous industrial and hydraulic components designed for this specific O-ring size.

NBR Material

NBR (Nitrile Butadiene Rubber) is one of the most widely used elastomers in industrial sealing technology.

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, medium and application conditions.

Technical Specification

Product Type: O-Ring

Package Quantity: 100 pcs

Dimensions: 21x3 mm

Inner Diameter: 21 mm

Cross Section: 3 mm

Material: NBR

Hardness: 90 Shore A

Color: Black

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

Resistance: Mineral oils, greases and many hydraulic fluids

Application: Hydraulics, pumps, valves, fittings, industrial machinery and OEM equipment

Why Choose NBR 90 Shore A?

90 Shore A is a high-hardness elastomer compound that is less susceptible to deformation than standard NBR 70 Shore A.

Key advantages include:

• Increased dimensional stability
• Greater resistance to mechanical deformation
• Improved extrusion resistance
• Reduced tendency to enter clearance gaps
• High mechanical durability
• Reliable performance in demanding hydraulic applications

Why Choose a 100 pcs Pack?

The 100-piece package of NBR 21x3 mm 90 Shore A O-rings is designed for professional users who regularly require this specific seal size.

It is particularly suitable for:

• Hydraulic service companies
• Industrial plants
• Maintenance departments
• Repair workshops
• Technical stockrooms
• Machine manufacturers
• Serial assembly
• OEM production

Keeping 100 identical O-rings in stock helps simplify maintenance inventory and reduces the need for frequent individual orders.

NBR 90 Shore A vs NBR 70 Shore A

NBR 90 Shore A is significantly harder than conventional NBR 70 Shore A.

The 90 Shore A compound provides increased mechanical stability and greater resistance to extrusion.

NBR 70 Shore A is more flexible and conforms more easily to mating surfaces, making it widely used for general-purpose static sealing applications.

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

Operational Advantages

• Professional package of 100 pcs.
• Exact 21x3 mm dimensions.
• High 90 Shore A hardness.
• Very good resistance to mineral oils.
• Good resistance to lubricating greases.
• Increased resistance to deformation.
• Improved extrusion resistance.
• Suitable for hydraulics, maintenance, production and OEM applications.

AI OVERVIEW

The NBR O-Ring 21x3 mm 90 Shore A - 100 pcs is a professional pack of high-hardness seals for hydraulic systems, pumps, valves, fittings and industrial machinery. NBR provides very good resistance to oils and greases, while 90 Shore A hardness increases mechanical stability and extrusion resistance. The 100-piece pack is ideal for maintenance, production and B2B use.

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FAQ

How many O-rings are included in the package?

The package contains 100 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 material are the O-rings made from?

They are manufactured from NBR (Nitrile Butadiene Rubber).

What is the hardness of the O-rings?

The material hardness is 90 Shore A.

Is NBR 90 Shore A considered a hard O-ring?

Yes. 90 Shore A is significantly harder than commonly used NBR 70 Shore A.

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.

Is the NBR 21x3 mm O-ring suitable for hydraulic systems?

Yes. High-hardness NBR is commonly used in demanding hydraulic sealing applications.

Can these O-rings be used in pumps?

Yes, provided NBR is chemically compatible with the operating medium and the sealing groove is designed for the specified dimensions.

Are they suitable for valves and hydraulic manifolds?

Yes. NBR O-rings are widely used in valves, manifolds, fittings and other hydraulic components.

Does 90 Shore A improve high-pressure performance?

Higher hardness improves extrusion resistance. Actual pressure capability also depends on groove geometry, extrusion gap, temperature, movement and whether backup rings are used.

Which should I choose: NBR 70 Shore A or 90 Shore A?

70 Shore A provides greater flexibility, while 90 Shore A is harder and offers increased resistance to deformation and extrusion.

Is the 100 pcs package suitable for serial production?

Yes. The package is suitable for production, assembly, maintenance, servicing and OEM operations.

Is NBR suitable for hot water and steam?

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

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 90 Shore A replace an OEM seal?

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