O-Ring 244.3x5.7 NBR 70 Shore A

What Is the O-Ring 244.3x5.7 NBR 70 Shore A?

O-Ring 244.3x5.7 NBR 70 Shore A is a large-diameter technical sealing ring manufactured from NBR (Nitrile Butadiene Rubber, Buna-N). It has an inside diameter of 244.3 mm and a cross-section of 5.7 mm. The 70 Shore A hardness provides a practical balance between elasticity and resistance to mechanical deformation. This size is particularly suitable for sealing large housings, covers, flanges, pumps and industrial machinery operating with media compatible with NBR.

Technical Specification

Product Type: O-Ring / Sealing Ring

Material: NBR, Nitrile Butadiene Rubber, Buna-N

Hardness: 70 Shore A

Inside Diameter: 244.3 mm

Cross Section: 5.7 mm

Approximate Outside Diameter: 255.7 mm

Colour: Black

Typical Operating Temperature: approximately -30°C to +100°C

Media Compatibility: mineral oils, mineral-based hydraulic oils, lubricating greases and other compatible industrial fluids

Large 244.3x5.7 NBR O-Ring for Industrial Applications

The 244.3 mm inside diameter makes this O-ring suitable for relatively large mechanical components where continuous circumferential sealing is required.

Typical applications include:

• Machinery housings
• Large covers
• Flanged connections
• Industrial pumps
• Hydraulic assemblies
• Gear housings
• Technical tanks
• Drive assemblies
• Production machinery
• Industrial equipment

Before installation, the groove geometry, required compression, operating temperature and compatibility of NBR with the working medium should be verified.

Why NBR 70 Shore A?

NBR 70 Shore A is widely used for industrial sealing applications, particularly where the elastomer is exposed to mineral oils and lubricating greases.

Important properties of NBR include:

• Very good resistance to mineral oils
• Good resistance to lubricating greases
• Good abrasion resistance
• Good mechanical strength
• Suitable elasticity
• Resistance to permanent mechanical deformation under appropriate operating conditions
• Wide applicability in industrial sealing systems

The 70 Shore A hardness is commonly used for general-purpose technical O-rings because it combines sufficient flexibility for sealing with mechanical stability.

Hydraulic Applications

The O-Ring 244.3x5.7 NBR can be used in appropriately designed hydraulic connections operating with compatible mineral oil-based hydraulic fluids.

For a seal of this diameter, correct positioning inside the groove is particularly important. The O-ring should not be twisted, locally stretched or unevenly compressed during assembly.

Pressure, temperature, groove dimensions and the type of hydraulic fluid must be considered when determining suitability for a specific application.

Sealing Covers, Housings and Flanges

The 244.3x5.7 mm O-ring is particularly suitable for large static sealing arrangements.

Typical examples include sealing between:

• Housing and cover
• Pump body and cover
• Flange surfaces
• Machine casings
• Hydraulic components
• Industrial equipment covers

When the components are assembled, the O-ring cross-section is compressed in a controlled manner inside the groove, creating the required sealing contact.

Machinery Service and Maintenance

Large NBR O-rings are frequently replaced during maintenance of pumps, gearboxes, housings and industrial equipment.

When identifying a replacement seal, technicians should verify:

• Inside diameter
• Cross-section
• Elastomer material
• Hardness
• Groove dimensions
• Operating medium
• Temperature
• Static or dynamic application

A similar diameter alone is not sufficient to confirm interchangeability.

Installation Recommendations

Before installing the 244.3x5.7 NBR O-Ring, clean the groove and mating surfaces thoroughly.

During installation:

• Avoid twisting the O-ring
• Protect the seal from sharp edges
• Avoid unnecessary stretching
• Check its position around the complete circumference
• Do not pinch the seal between mating surfaces
• Use only assembly lubricants compatible with NBR

With a large 244.3 mm diameter, checking the entire circumference before closing the housing or tightening the flange helps prevent local displacement of the seal.

Frequently Asked Questions (FAQ)

What does O-Ring 244.3x5.7 mean?
The O-ring has an inside diameter of 244.3 mm and a cross-section diameter of 5.7 mm.

What is the outside diameter of a 244.3x5.7 O-ring?
The nominal outside diameter is approximately 255.7 mm, calculated as the inside diameter plus twice the cross-section.

Is NBR 70 Shore A resistant to oil?
Yes. NBR provides very good resistance to many mineral oils and is widely used in oil-lubricated machinery.

Can the O-Ring 244.3x5.7 be used to seal a machine cover?
Yes, provided the sealing groove is designed for this size and NBR is compatible with the operating medium and temperature.

Can a 5.7 mm cross-section be replaced by a 6 mm O-ring?
Not without checking the groove dimensions. A larger cross-section changes the compression ratio and may cause excessive compression or incorrect sealing.

Frequently Asked Questions from Service Technicians and Engineers

Can a large O-ring be stretched during installation?
Limited stretching may occur in some installation arrangements, but it should remain within the design requirements of the sealing system.

Why can a large O-ring twist during assembly?
Twisting may occur when the seal is dragged over a surface or positioned unevenly in the groove. Its entire circumference should be checked before the connection is closed.

Is NBR suitable for lubricating grease?
Yes. NBR offers good resistance to many mineral oil-based lubricating greases.

Is the 244.3x5.7 O-ring suitable for static sealing?
Yes. Large-diameter O-rings are commonly used for static sealing of covers, housings, flanges and other mechanical connections.

What should be checked when selecting a replacement?
Verify the 244.3 mm inside diameter, 5.7 mm cross-section, NBR material, 70 Shore A hardness, groove dimensions and actual operating conditions.