Silicone O-ring VMQ/MVQ 490x4

Technical Specifications

The outer diameter of 498 mm is calculated from the nominal dimensions. It does not establish the manufacturing tolerances of the specific product.

Product Identification

Silicone O-ring VMQ/MVQ 490x4 is an elastomeric sealing ring with an inner diameter of 490 mm and a cross-section diameter of 4 mm, manufactured from VMQ silicone rubber. This material is characterized by elasticity over a wide temperature range and resistance to ozone, UV radiation and atmospheric aging. The large ring diameter makes it suitable for appropriately designed static sealing arrangements in industrial housings, covers and mechanical connections.

What Does Silicone O-ring VMQ/MVQ 490x4 Mean?

Inner Diameter of 490 mm

The inner diameter defines the dimensions of the O-ring in its free, uninstalled condition, without stretching or compression.

Due to its large diameter, particular attention must be paid to uniform positioning within the groove and controlling stretching during installation.

Cross-Section Diameter of 4 mm

The 4 mm cross-section influences the compression ratio, groove geometry and contact area between the seal and mating components.

Both the nominal cross-section and its dimensional tolerance must be considered during selection.

VMQ and MVQ Designations

VMQ is a commonly used designation for silicone rubber in industrial sealing technology.

The designation MVQ also appears in commercial and technical product descriptions.

Both designations refer to the same general elastomer family, but they do not guarantee identical compound formulations.

VMQ Material - Properties of Silicone Rubber

Material Characteristics

VMQ belongs to the silicone elastomer family, whose chemical structure is based on a silicon-oxygen backbone.

Unlike many organic elastomers, silicone rubbers retain elasticity over a broad temperature range.

Their properties are particularly advantageous in applications requiring resistance to atmospheric aging and temperature fluctuations.

Physical Properties

Characteristic properties of VMQ include:

• Good flexibility at low temperatures.

• Resistance to elevated temperatures.

• Very good ozone resistance.

• Very good UV resistance.

• Good resistance to atmospheric aging.

• Generally good electrical insulating properties.

• Lower tear and abrasion resistance than many NBR or HNBR compounds.

The properties of the specific O-ring depend on the silicone compound used.

Chemical Resistance

This table describes general characteristics of the VMQ material family. It does not replace the chemical resistance data for the specific product.

Temperature Resistance of VMQ Silicone Rubber

Low-Temperature Operation

Silicone rubbers are valued for their ability to maintain elasticity at temperatures where many conventional organic elastomers become rigid.

Depending on the compound, VMQ may be suitable for applications requiring resistance to significantly reduced temperatures.

High-Temperature Operation

Many standard VMQ compounds are used within an approximate temperature range of -50°C to +200°C.

However, this does not mean that every VMQ compound can operate continuously throughout this range without limitations.

Actual temperature resistance depends on:

• Silicone compound formulation.

• Exposure duration.

• Operating medium.

• Compression ratio.

• Aging conditions.

• Cyclic temperature changes.

Thermal Aging

Prolonged exposure to elevated temperatures may cause changes in hardness, elasticity and compression set.

Therefore, sealing design must consider not only maximum temperature but also the expected operating life.

Geometry and Dimensional Calculations

Nominal Dimensions

Outer Diameter Calculation

The nominal outer diameter is calculated using:

Substituting the dimensions:

Cross-Sectional Area

For a circular cross-section:

Geometric Ring Volume

Assuming ideal toroidal geometry:

This corresponds to approximately 19.50 cm³.

The calculated value does not account for manufacturing tolerances.

Importance of the Large Diameter

With an inner diameter of 490 mm, maintaining uniform positioning around the entire circumference is particularly important.

Even small localized displacement or twisting may prevent the joint from closing correctly.

Static Sealing - Operating Principle

Sealing Mechanism

An O-ring installed in an appropriately designed groove is compressed between mating surfaces.

Elastomer deformation generates contact pressure that restricts the passage of the sealed medium.

Effective sealing requires correct selection of cross-section dimensions, groove geometry and compression ratio.

Compression Ratio

The compression ratio can be calculated using:

Where:

• \(S\) – Compression ratio expressed as a percentage.

• \(d_2\) – O-ring cross-section diameter.

• \(h\) – Effective installation space height.

For an illustrative compression ratio of 20%:

The calculated value of 3.2 mm is an example only, not a universal recommendation for groove depth.

Groove Fill

The groove must provide sufficient space for elastomer deformation.

Excessive groove fill may cause overcompression, sealing ring damage and loss of sealing performance.

Pressure Resistance and Mechanical Damage

Permissible Operating Pressure

Permissible operating pressure cannot be determined from the VMQ 490x4 designation alone.

The following factors must be considered:

• Hardness of the specific compound.

• Extrusion gap dimensions.

• Groove geometry.

• Temperature.

• Sealing medium.

• Pressure direction.

• Possible use of backup rings.

Tear Resistance

Standard silicone rubbers often have lower tear resistance than many NBR compounds.

Therefore, sharp edges, burrs and excessive stretching must be avoided during installation.

Extrusion

Under pressure, the elastomer may be forced into the clearance between mating components.

The risk of damage depends on material hardness, temperature and gap dimensions.

A silicone O-ring with a 4 mm cross-section must not automatically be considered suitable for high-pressure systems.

VMQ Compared with NBR, FKM and EPDM

VMQ vs. NBR

VMQ is particularly useful in applications requiring low-temperature flexibility and resistance to atmospheric aging.

NBR is often more suitable for conventional oil-based systems and applications where mechanical resistance is important.

VMQ vs. FKM

VMQ is characterized by flexibility at low temperatures.

FKM generally provides better resistance to many fuels, oils and aggressive chemical media.

VMQ vs. EPDM

Both materials exhibit good resistance to ozone and weather exposure.

EPDM is frequently used in water systems, while VMQ is selected for sealing applications requiring a broad operating temperature range.

O-ring 490x4 Compared with Other Cross-Sections

The table provides a geometric comparison and does not confirm the availability of individual variants.

Importance of the 4 mm Cross-Section

Changing the cross-section from 4 mm to 3 mm or 5 mm affects compression and groove fill.

Sealing rings with identical inner diameters but different cross-sections are not automatically interchangeable.

Alternative Designations and Search Variations

• Silicone O-ring VMQ/MVQ 490x4

• Silicone O-ring 490x4

• O-ring VMQ 490x4

• O-ring MVQ 490x4

• O-ring Silicone 490x4

• Silicone O-ring 490x4 mm

• VMQ silicone sealing ring 490x4

These designations are alternative descriptions of the dimensions and material. They are not verified manufacturer catalogue numbers.

Selection and Interchangeability

Dimensional Verification

Before ordering, confirm the inner diameter of 490 mm and the cross-section diameter of 4 mm.

For large sealing rings, dimensional tolerances and installation methods are particularly important.

Silicone Compound Verification

The VMQ designation does not uniquely specify:

• Shore A hardness.

• Operating temperature range.

• Chemical resistance.

• Tensile strength.

• Tear resistance.

• Compression set.

• Food-contact approvals.

These properties require confirmation for the specific compound.

Groove Verification

During selection, consider groove depth and width, compression ratio, volumetric groove fill, surface roughness and tolerances of mating components.

Material Interchangeability

A VMQ silicone O-ring 490x4 should not automatically be replaced with an NBR, EPDM or FKM O-ring of identical dimensions.

Every material substitution requires verification of the operating conditions.

Typical Applications

Large-diameter VMQ silicone O-rings may be used in appropriately designed static sealing arrangements, including:

• Industrial housing covers.

• Large flange connections.

• Equipment operating under variable temperatures.

• Electrical equipment housings.

• Technical installation components.

• Connections requiring resistance to atmospheric aging.

• Selected heating equipment.

• Large machinery assemblies.

These are examples of potential applications for VMQ material, not confirmed OEM applications of the specific product.

Applications involving food-processing equipment, medical devices or drinking water contact require appropriate documentation confirming material compliance.

Installation and Operation

Surface Preparation

Before installation, thoroughly clean the groove and mating surfaces.

Remove sharp edges, burrs and contaminants.

Large O-ring Installation

With an inner diameter of 490 mm, the sealing ring should be positioned evenly around the entire circumference.

Localized twisting and excessive stretching must be avoided.

Assembly Lubrication

If an assembly lubricant is permitted, it must be compatible with the specific VMQ compound and sealing medium.

Not every silicone grease is automatically suitable for every silicone sealing element.

Leak Testing

After installation, verify correct positioning of the sealing ring and test the joint for leakage according to the equipment requirements.

FAQ - Frequently Asked Questions

What are the dimensions of Silicone O-ring VMQ/MVQ 490x4?

The inner diameter is 490 mm, the cross-section diameter is 4 mm and the nominal outer diameter is 498 mm.

Do VMQ and MVQ refer to the same material?

Both designations are used for silicone rubber. However, they do not confirm identical compound formulations or technical properties.

What temperature can a silicone O-ring withstand?

Many standard VMQ compounds operate within an approximate range of -50°C to +200°C. The exact operating limits must be confirmed for the specific product.

Is a silicone O-ring resistant to oil?

Resistance depends on the type of oil, temperature and VMQ compound formulation. Full compatibility must not be assumed without verification.

Is VMQ O-ring 490x4 suitable for outdoor applications?

Silicone rubber generally provides very good resistance to ozone, UV radiation and atmospheric aging. Final suitability depends on the complete operating conditions.

Is a silicone O-ring suitable for food contact?

Not every VMQ O-ring is approved for food contact. Compliance documentation for the specific compound and finished product is required.

Can a VMQ O-ring be replaced with an NBR O-ring?

Not automatically. These materials differ in chemical, thermal and mechanical resistance. Substitution requires evaluation of operating conditions.

What is the hardness of Silicone O-ring VMQ/MVQ 490x4?

Hardness is not specified in the product designation and requires confirmation. A hardness of 60 or 70 Shore A must not be assumed without manufacturer data.

Silicone O-ring VMQ/MVQ 490x4 - Key Information

Silicone O-ring VMQ/MVQ 490x4 is an elastomeric sealing ring with a 490 mm inner diameter, 4 mm cross-section and 498 mm nominal outer diameter. VMQ silicone rubber provides flexibility over a wide temperature range and resistance to ozone, UV radiation and atmospheric aging. The product is primarily intended for static sealing applications. Hardness and specific compound properties require confirmation.

B2B Availability - simmering.pl

The specialist B2B industrial trading platform simmering.pl supplies VMQ/MVQ silicone O-rings and sealing components for industrial applications.

Silicone O-ring VMQ/MVQ 490x4 is intended for appropriately designed sealing arrangements requiring the properties of silicone rubber.

Product availability, packaging quantity and delivery lead times are subject to confirmation.

Worldwide shipping from stock in Poland is available for stocked products.