O-Ring 145x3 NBR 70 ShA
1 pcs.
€35.44
(net)
Price for: 100pcs.
O-Ring 145x3 NBR 70 ShA - Large Diameter Industrial Sealing Ring
O-Ring 145x3 NBR 70 ShA is a technical sealing ring with a 145 mm inside diameter and 3 mm cross-section, manufactured from NBR nitrile butadiene rubber with a nominal hardness of 70 Shore A. Its nominal outside diameter is 151 mm. The combination of a large 145 mm diameter and relatively slim 3 mm section makes this O-ring suitable for appropriately designed housings, covers, pumps, hydraulic assemblies and industrial machinery requiring continuous circumferential sealing.
Technical Specifications
Product Type: O-Ring / sealing ring
Material: NBR - Nitrile Butadiene Rubber / Buna-N
Hardness: 70 ShA / 70 Shore A
Inside Diameter: 145 mm
Cross-Section: 3 mm
Nominal Outside Diameter: 151 mm
Color: Black
Typical Temperature Range: approximately -30 to +100°C for standard NBR compounds
Chemical Resistance: Many mineral oils, lubricating greases and compatible technical fluids
Application: Industrial machinery, hydraulics, pumps, housings, covers and mechanical assemblies
The exact temperature range and chemical resistance depend on the specific NBR compound, operating medium and actual service conditions.
145x3 mm O-Ring Dimensions
The principal dimensions are:
Inside Diameter: 145 mm
Cross-Section: 3 mm
Nominal Outside Diameter: 151 mm
The nominal outside diameter is calculated as:
145 + 3 + 3 = 151 mm
O-rings are normally identified by their inside diameter and cross-section. Therefore, the primary dimensional designation for this product is 145x3 mm.
Large 145 mm Diameter with 3 mm Cross-Section
A characteristic feature of this O-ring is the combination of a 145 mm inside diameter with a 3 mm cross-section.
This geometry is suitable for larger mechanical components that use a relatively compact sealing groove.
Compared with O-rings having a thicker cross-section, the 3 mm section requires a groove specifically designed for this size.
Correct positioning is particularly important with a large-diameter ring. The O-ring should be seated uniformly around the entire circumference without twisting or localized overstretching.
Why NBR 70 ShA?
NBR 70 Shore A is one of the most widely used material and hardness combinations in industrial sealing technology.
NBR provides good resistance to many:
- mineral oils
- lubricating greases
- compatible hydraulic oils
- machine lubricants
- oil-based technical fluids
The 70 Shore A hardness provides a practical balance between elasticity, sealing contact and resistance to deformation.
This makes NBR 70 ShA suitable for many general industrial, hydraulic and mechanical sealing applications.
Industrial Applications
The 145x3 NBR 70 ShA O-ring can be used in appropriately designed:
- industrial machinery
- pumps
- hydraulic systems
- mechanical housings
- equipment covers
- flange connections
- drive assemblies
- production equipment
- machine components
- static sealing joints
Suitability for a specific application depends on groove dimensions, pressure, temperature, medium and operating conditions.
Sealing Housings and Covers
The large diameter makes the 145x3 mm O-ring particularly relevant to static sealing interfaces between housings, covers and other mechanical components.
When the assembly is closed, the O-ring cross-section is compressed within its groove.
This controlled deformation creates sealing contact between the elastomer and mating surfaces.
Reliable sealing depends on:
- groove geometry
- O-ring compression
- surface condition
- operating pressure
- temperature
- fluid compatibility
- dimensional stability of the assembly
Hydraulic Applications
NBR 70 ShA is widely used in hydraulic equipment operating with compatible mineral oil based hydraulic fluids.
The 145x3 NBR O-ring may be used in larger hydraulic housings, covers and assemblies where this exact sealing dimension is specified.
For higher-pressure applications, the extrusion gap and groove geometry must also be considered.
Pressure capability cannot be determined from O-ring dimensions alone.
Pumps and Industrial Equipment
Large-diameter O-rings are frequently used where removable covers, housings or other circular mechanical interfaces require sealing.
A 145x3 mm NBR O-ring can provide a continuous elastomeric sealing element around such an interface.
Potential applications include pumps, machine housings, hydraulic equipment and industrial assemblies operating with fluids compatible with NBR.
Resistance to Oils and Greases
One of the principal advantages of NBR is its compatibility with many conventional mineral oils and lubricating greases.
This is why nitrile rubber is commonly used in:
- machine building
- hydraulic equipment
- lubrication systems
- industrial maintenance
- mechanical assemblies
- MRO applications
NBR is not universally compatible with every chemical or operating fluid. Compatibility should be verified when unusual media or demanding temperatures are involved.
Installation of a 145x3 O-Ring
Large-diameter O-rings require careful handling during installation.
Before assembly, the groove and mating surfaces should be clean and free from damage.
Avoid:
- twisting the O-ring
- excessive localized stretching
- cutting the elastomer
- pulling the ring across sharp edges
- pinching the seal during assembly
- leaving part of the O-ring outside the groove
If an assembly lubricant is used, it should be compatible with both NBR and the operating medium.
O-Ring 145x3 vs 145x3.5
These two sizes should not automatically be treated as interchangeable.
The 145x3 O-ring has:
Inside Diameter: 145 mm
Cross-Section: 3 mm
Outside Diameter: 151 mm
The 145x3.5 O-ring has:
Inside Diameter: 145 mm
Cross-Section: 3.5 mm
Outside Diameter: 152 mm
Although both have the same inside diameter, increasing the cross-section from 3 to 3.5 mm represents approximately a 16.7% increase in cross-sectional diameter.
This significantly affects groove filling and compression. A 145x3.5 O-ring should therefore not automatically be installed in a groove designed for 145x3 mm.
Groove Design for a 3 mm Cross-Section
The sealing groove should be designed specifically for the 3 mm cross-section.
An excessively shallow groove can over-compress the O-ring, while an excessively deep groove can provide insufficient sealing compression.
Groove width, depth and extrusion clearance should correspond to the actual operating conditions.
This is especially important when the O-ring operates under pressure.
Storage of NBR O-Rings
NBR O-rings should be stored under conditions that minimize premature elastomer ageing.
Protect the seals against:
- direct sunlight
- UV radiation
- ozone
- excessive heat
- aggressive chemicals
- permanent stretching
- mechanical deformation
Large O-rings should not be stored in a way that produces continuous localized stretching or deformation.
How to Select a 145x3 NBR O-Ring
Before installation, verify:
Inside Diameter: 145 mm
Cross-Section: 3 mm
Material: NBR
Hardness: 70 ShA
Nominal Outside Diameter: 151 mm
Operating Medium: Compatible with NBR
Temperature: Suitable for the specific compound
Pressure: Suitable for the sealing arrangement
Groove Geometry: Designed for a 3 mm cross-section
Application: Static or appropriately designed dynamic sealing
Dimensions alone are not sufficient to determine complete suitability for a specific machine or sealing system.
Operational Advantages
145 mm inside diameter: suitable for larger industrial sealing interfaces.
3 mm cross-section: provides a relatively slim sealing profile for appropriately designed grooves.
NBR 70 ShA: widely used elastomer and hardness combination for technical sealing.
Oil and grease resistance: NBR is compatible with many mineral oils and lubricating greases.
Continuous sealing ring: provides circumferential sealing without a joint in the O-ring.
Industrial versatility: suitable for appropriately designed pumps, housings, covers, hydraulic components and industrial machinery.
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FAQ - O-Ring 145x3 NBR 70 ShA
What are the dimensions of the 145x3 NBR O-ring?
The O-ring has a 145 mm inside diameter and 3 mm cross-section.
What is the outside diameter of a 145x3 O-ring?
The nominal outside diameter is 151 mm.
What material is this O-ring made from?
It is manufactured from NBR nitrile butadiene rubber, also known as Buna-N.
What does 70 ShA mean?
70 ShA indicates the nominal hardness of the elastomer measured on the Shore A scale.
Is the 145x3 NBR O-ring resistant to oil?
NBR provides good resistance to many mineral oils and lubricating greases. Compatibility should still be verified for the specific fluid and operating temperature.
Can a 145x3 NBR O-ring be used in hydraulic equipment?
Yes, provided the hydraulic fluid is compatible with NBR and the groove, pressure and temperature conditions are suitable.
Frequently Asked Questions by Engineers
Does 145x3 mean inside diameter and cross-section?
Yes. 145 mm is the nominal inside diameter and 3 mm is the cross-sectional thickness.
Can a 145x3 O-ring be replaced with a 145x3.5 O-ring?
Not automatically. The larger cross-section changes groove filling and compression and may result in incorrect assembly or sealing conditions.
Why is correct installation important with a 145 mm O-ring?
A large-diameter ring can be unintentionally twisted or stretched unevenly while being positioned in the groove. Uniform installation around the complete circumference is important.
Can NBR 70 ShA be used for static sealing?
Yes. NBR 70 ShA is widely used in appropriately designed static sealing systems involving compatible operating media.
Is the 151 mm outside diameter the primary ordering dimension?
Normally no. O-rings are primarily identified by their inside diameter and cross-section, so the correct dimensional designation is 145x3 mm.
