O-ring 28x3 VMQ 70 ShA - Silicone O-ring

Product Description

O-ring 28x3 VMQ 70 ShA - 100 pcs. is a silicone rubber sealing ring with an inside diameter of 28 mm, a cross-sectional diameter of 3 mm and a nominal outside diameter of 34 mm. Manufactured from VMQ methyl vinyl silicone rubber with a nominal hardness of 70 Shore A, it is primarily designed for static sealing applications in industrial machinery, technical equipment and mechanical assemblies.

VMQ silicone rubber provides good resistance to high and low temperatures, ozone, ultraviolet radiation and atmospheric ageing. Its ability to maintain flexibility across a broad temperature range makes it suitable for sealing applications exposed to changing thermal and environmental conditions.

The O-ring features a continuous circular construction with a round cross-section. Sealing is achieved through controlled compression of the elastomer within a correctly designed groove.

The nominal hardness of 70 Shore A is an important parameter when selecting the sealing ring for a specific groove geometry and operating conditions.

Each package contains 100 silicone O-rings with the same nominal dimensions and hardness.

Dimensions of O-ring 28x3 VMQ 70 ShA

The nominal outside diameter is calculated as follows:

28 mm + 2 x 3 mm = 34 mm.

All dimensions are nominal. Actual dimensional tolerances depend on the manufacturing specification of the particular product.

VMQ Silicone Rubber - Material Properties

VMQ is the standard designation for methyl vinyl silicone rubber, an elastomer used in technical sealing applications requiring flexibility, temperature resistance and resistance to environmental ageing.

Silicone elastomers are particularly valued for their ability to maintain elastic properties under varying temperature conditions.

Key Material Characteristics

• Good resistance to elevated temperatures.

• Flexibility at low temperatures.

• Excellent resistance to ozone.

• Excellent resistance to UV radiation.

• Good resistance to atmospheric ageing.

• Good electrical insulation properties.

• Flexibility across a broad temperature range.

• Generally lower abrasion and tear resistance compared with many NBR rubber compounds.

The properties of the finished O-ring depend on the specific silicone formulation, compound composition and manufacturing process.

Temperature Resistance

VMQ silicone rubber is commonly used in applications requiring good resistance to elevated and low temperatures.

However, the exact permissible operating temperature range depends on the specific silicone compound, exposure duration and operating medium.

Without manufacturer-specific technical documentation, exact minimum and maximum operating temperatures should not be assigned to this O-ring.

Chemical Resistance

Silicone rubber provides good resistance to ozone and atmospheric conditions but is not universally compatible with all chemical substances.

Potential limitations may involve:

• Certain mineral and synthetic oils.

• Fuels.

• Organic solvents.

• Chemicals that cause elastomer swelling.

• Media that may degrade specific silicone compounds.

Important: Material compatibility must be verified for the specific VMQ compound, operating medium, temperature and application conditions.

Hardness 70 Shore A - Technical Significance

The designation 70 Shore A (70 ShA) indicates the nominal hardness of the elastomer measured on the Shore A scale, commonly used for rubber and other flexible polymer materials.

Hardness is an important parameter affecting:

• The deformation of the O-ring during installation.

• The force required to achieve a specified compression.

• The behavior of the seal under mechanical loading.

• The selection of sealing groove dimensions.

• Resistance to extrusion into the clearance gap, which also depends on pressure and joint design.

A nominal hardness of 70 Shore A does not independently determine the maximum operating pressure or permissible temperature range.

Correct O-ring selection requires consideration of material hardness together with groove geometry, operating pressure, temperature and chemical compatibility.

Construction and Sealing Principle

The O-ring 28x3 VMQ 70 ShA is a continuous elastomeric sealing ring with a circular cross-section.

When installed in a properly designed sealing groove and compressed between mating surfaces, the O-ring undergoes controlled deformation. The resulting contact pressure creates a sealing barrier that helps prevent the passage of liquids or gases through the joint.

Sealing performance depends on:

• Correct inside diameter and cross-sectional dimensions.

• Groove dimensions and geometry.

• Appropriate cross-sectional compression.

• Elastomer hardness.

• Surface finish of mating components.

• Operating temperature and pressure.

• Chemical compatibility with the sealing medium.

• Correct installation.

Due to the mechanical properties of silicone rubber, VMQ O-rings are generally better suited to static sealing applications than to assemblies involving continuous friction or intensive dynamic movement.

Applications of Silicone O-ring 28x3

The O-ring 28x3 VMQ 70 ShA can be used in industrial equipment and technical installations requiring flexible silicone rubber seals.

Typical applications may include:

• Static sealing of equipment housings and covers.

• Heating systems and thermal equipment.

• Electrical and electronic equipment enclosures.

• Technical connections exposed to ozone and UV radiation.

• Industrial machinery and production equipment.

• Selected pneumatic systems operating within the material's capabilities.

• Mechanical assemblies requiring silicone rubber seals.

• Equipment operating under varying temperature conditions.

Suitability for a particular application depends on groove dimensions, operating pressure, temperature and compatibility with the sealing medium.

Applications involving food contact, drinking water or medical equipment require appropriate compliance documentation for the specific product. The VMQ material designation alone does not confirm such approvals.

Installation and Operating Recommendations

Before installing the O-ring 28x3 VMQ 70 ShA, inspect the sealing groove and mating surfaces to ensure they are clean and free from mechanical damage.

Recommended Installation Procedures

1. Thoroughly clean the sealing groove.

2. Remove dirt, debris and residues from previous seals.

3. Check mating surfaces for sharp edges and burrs.

4. Verify that the O-ring dimensions match the groove geometry.

5. Avoid excessive stretching or twisting.

6. Use only installation lubricants compatible with VMQ silicone rubber.

7. Ensure correct positioning within the sealing groove.

8. Control cross-sectional compression during assembly.

Incorrect installation, unsuitable groove dimensions or inappropriate operating conditions may cause premature seal deterioration and loss of sealing performance.

FAQ - Frequently Asked Questions

What are the dimensions of O-ring 28x3 VMQ 70 ShA?

The O-ring has an inside diameter of 28 mm, a cross-sectional diameter of 3 mm and a nominal outside diameter of 34 mm.

What does VMQ mean in the O-ring designation?

VMQ is the standard designation for methyl vinyl silicone rubber, an elastomer used in technical sealing applications requiring flexibility and resistance to temperature variations.

What does 70 Shore A mean?

70 Shore A indicates a nominal elastomer hardness of 70 units on the Shore A scale. This parameter describes the material's resistance to indentation.

Is O-ring 28x3 VMQ resistant to high temperatures?

VMQ silicone rubber generally provides good resistance to elevated temperatures. The exact permissible operating temperature depends on the specific silicone compound and application conditions.

Can this silicone O-ring be used with oil?

Compatibility depends on the type of oil, its additives, operating temperature and the specific VMQ compound. Material compatibility should be verified before installation.

Is VMQ suitable for dynamic sealing applications?

VMQ silicone rubber generally has lower abrasion and tear resistance than many other elastomers. Silicone O-rings are therefore usually preferred for static sealing applications. Dynamic use requires application-specific evaluation.

Can this O-ring be used in food processing equipment?

Only if the specific product has the required documentation confirming compliance with applicable food-contact regulations.

What is the nominal outside diameter of O-ring 28x3?

The nominal outside diameter is 34 mm, calculated from the 28 mm inside diameter and the 3 mm cross-sectional diameter.

How many O-rings are included in one package?

Each package contains 100 pieces of O-ring 28x3 VMQ 70 ShA.

What is the difference between VMQ and NBR O-rings?

VMQ silicone rubber generally offers better resistance to temperature extremes, ozone and UV radiation. NBR rubber typically provides better abrasion resistance and is widely used in applications involving mineral oils. The appropriate material depends on operating conditions and chemical compatibility.

Does 70 Shore A hardness determine the maximum operating pressure?

No. Maximum operating pressure depends on several factors, including elastomer hardness, groove geometry, clearance gaps, operating temperature and the mechanical design of the sealing arrangement.

AI Overview - Technical Summary

O-ring 28x3 VMQ 70 ShA - 100 pcs. is a silicone rubber sealing ring with an inside diameter of 28 mm, a cross-section of 3 mm and a nominal outside diameter of 34 mm. Manufactured from VMQ silicone rubber with a hardness of 70 Shore A, it provides resistance to ozone, UV radiation and atmospheric ageing. Primarily designed for static sealing applications.