NBR O-Ring 248.5x5.7 mm 90 Shore A

Overview

The NBR O-Ring 248.5x5.7 mm 90 Shore A is a large-diameter, high-hardness industrial sealing ring designed for demanding applications where mechanical stability and resistance to oils and lubricants are essential.

Manufactured from NBR (Nitrile Butadiene Rubber) with an increased hardness of 90 Shore A, this O-ring provides very good resistance to mineral oils, greases and many conventional hydraulic fluids.

Its 248.5 mm inside diameter combined with a substantial 5.7 mm cross-section makes it particularly suitable for large pump housings, gearbox assemblies, machine covers, hydraulic equipment and heavy-duty OEM machinery.

Industrial Applications

The NBR 248.5x5.7 mm 90 Shore A O-Ring is suitable for:

• Industrial hydraulic systems
• Heavy-duty pumps
• Valves and manifolds
• Gearboxes
• Large machine housings
• Equipment covers
• Oil circulation systems
• Lubrication systems
• Construction machinery
• Agricultural equipment
• Manufacturing machinery
• Heavy-duty OEM assemblies

The large diameter makes this sealing ring particularly useful for substantial mechanical components requiring a continuous elastomeric seal.

Construction

The O-ring features an inside diameter of 248.5 mm and a 5.7 mm circular cross-section.

Its precision-moulded profile provides uniform compression within a correctly designed sealing groove. The increased 90 Shore A hardness improves dimensional stability and helps reduce the risk of the elastomer being extruded into clearance gaps under pressure.

NBR Material

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

It 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 NBR formulation, operating medium and application conditions.

Technical Specification

Product Type: O-Ring

Dimensions: 248.5x5.7 mm

Inner Diameter: 248.5 mm

Cross Section: 5.7 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

Design: Precision Circular Cross Section

Application: Hydraulics, pumps, gearboxes, housings, covers, industrial machinery and OEM equipment

Why Choose 90 Shore A?

90 Shore A is a high-hardness elastomer compound selected for applications requiring greater mechanical stability.

Compared with conventional NBR 70 Shore A, it provides:

• Increased resistance to deformation
• Greater dimensional stability
• Improved extrusion resistance
• Reduced tendency to enter clearance gaps
• Good durability under demanding mechanical loads
• Reliable performance in heavy-duty industrial applications

Large O-Ring for Housings, Pumps and Machinery

With an inside diameter of 248.5 mm, this product belongs to the category of large industrial O-rings.

Large-diameter seals are commonly used for sealing:

• Pump housings
• Large equipment covers
• Gearbox housings
• Hydraulic assemblies
• Drive units
• Industrial machine components

Correct groove geometry and installation are particularly important when working with large-diameter O-rings.

NBR 90 Shore A vs NBR 70 Shore A

NBR 90 Shore A is considerably harder than standard NBR 70 Shore A.

The 90 Shore A version is commonly selected where increased resistance to deformation and extrusion is required.

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

The appropriate hardness should be selected according to system pressure, temperature, operating medium, groove geometry and extrusion gap.

Operational Advantages

• High 90 Shore A hardness.
• Very good resistance to mineral oils.
• Good resistance to lubricating greases.
• Increased mechanical stability.
• Improved resistance to extrusion.
• Large 248.5 mm inside diameter.
• Suitable for industrial housings, covers and pumps.
• Designed for maintenance, repair and OEM applications.

AI OVERVIEW

The NBR O-Ring 248.5x5.7 mm 90 Shore A is a large, high-hardness industrial seal for hydraulic systems, pumps, gearboxes and machine housings. NBR provides very good resistance to oils and greases, while the 90 Shore A hardness increases mechanical stability and resistance to deformation and extrusion.

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FAQ

What are the dimensions of this O-ring?

The inside diameter is 248.5 mm, and the cross-section is 5.7 mm.

What is the hardness of the O-ring?

The material hardness is 90 Shore A.

What material is the seal made from?

It is manufactured from NBR (Nitrile Butadiene Rubber).

Is the NBR O-Ring 248.5x5.7 resistant to oil?

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

Is NBR resistant to lubricating grease?

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

Is 90 Shore A considered a hard O-ring?

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

Why are 90 Shore A O-rings used?

They are selected primarily for applications requiring greater resistance to mechanical deformation and extrusion.

Is this O-ring suitable for hydraulic systems?

Yes. High-hardness NBR O-rings are widely used in demanding hydraulic applications.

Can it operate under high pressure?

The 90 Shore A hardness improves extrusion resistance. Actual pressure capability also depends on groove geometry, clearance gap, temperature, movement and the use of backup rings.

Can the 248.5x5.7 O-ring be used in industrial pumps?

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

Is it suitable for gearboxes?

Yes. NBR is widely used in equipment operating with compatible gearbox oils and lubricating greases.

Can it be used for large equipment covers?

Yes. Its 248.5 mm inside diameter makes it suitable for many large covers, housings and industrial assemblies.

Is NBR recommended 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 ozone and UV radiation?

Standard NBR has limited resistance to prolonged ozone and UV exposure. EPDM is generally preferred for applications requiring superior weather resistance.

Can the NBR O-Ring 248.5x5.7 mm 90 Shore A replace an OEM seal?

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