O-ring VMQ 21x3 70 Shore A GRN - Silicone Seal

O-ring VMQ 21x3 mm 70 Shore A - Silicone Rubber Sealing Ring GRN (100 pcs)

GRN O-ring 21x3 mm VMQ 70 Shore A is a silicone rubber sealing ring with a nominal inside diameter of 21 mm, a circular cross-section diameter of 3 mm and a hardness of 70 Shore A. Manufactured from silicone elastomer, also commercially designated MVQ, it is primarily intended for static sealing applications requiring flexibility and resistance to temperature variations. The calculated nominal outside diameter is 27 mm. The product is supplied in a pack of 100 pieces.

Technical Specifications - GRN O-ring 21x3 VMQ 70 Shore A

The nominal outside diameter is calculated as follows:

21 mm + 2 x 3 mm = 27 mm.

This is a calculated nominal dimension, not a measurement of an individual O-ring.

Exact dimensional tolerances, operating temperature limits, chemical resistance, permissible pressure and compression set properties depend on the specific silicone compound.

What Does 21x3 VMQ 70 Shore A Mean?

21 - Inside Diameter

The first number identifies the nominal inside diameter of the O-ring.

d1 = 21 mm

This dimension is used when selecting the ring for the corresponding mounting arrangement.

3 - Cross-Section Diameter

The second number identifies the diameter of the circular elastomer cross-section.

d2 = 3 mm

The cross-section influences groove design, compression requirements and the available sealing contact area.

VMQ / MVQ - Silicone Rubber

VMQ is the internationally recognized material designation for methyl vinyl silicone rubber.

MVQ is also encountered as a commercial designation for silicone elastomers.

Silicone rubber is valued for its flexibility at low temperatures and its ability to maintain useful elastomeric properties at elevated temperatures, subject to the specific compound formulation.

70 Shore A - Hardness

70 Shore A indicates the nominal hardness of the silicone elastomer according to the Shore A scale.

Hardness affects:

• Elastic deformation.

• Required compression force.

• Sealing contact pressure.

• Behavior under mechanical loading.

• Suitability for particular groove geometries.

Hardness alone does not determine the maximum permissible operating pressure.

Pack of 100 Pieces

The product is sold as a pack containing 100 individual O-rings of the same nominal size and material specification.

The quantity refers to individual sealing rings, not sets of multiple components.

Construction and Operating Principle

The GRN 21x3 VMQ 70 Shore A O-ring is a continuous silicone elastomer ring with a circular cross-section.

It does not contain a metal case, garter spring or additional sealing lips.

Sealing is achieved by controlled compression of the elastomer between mating surfaces.

During installation, the O-ring is placed into a correctly designed groove. When the components are assembled, the elastomer cross-section deforms and creates sealing contact.

Effective sealing depends on:

• Groove dimensions.

• Cross-section compression.

• Installation stretch.

• Clearance between mating components.

• Operating pressure.

• Temperature.

• Chemical compatibility.

• Surface finish.

• Static or dynamic operating conditions.

Silicone VMQ - Material Properties

Silicone rubber is used in sealing applications where temperature flexibility and resistance to environmental aging are important.

Main Characteristics of Silicone Rubber

• Good flexibility at low temperatures.

• Resistance to elevated temperatures within the limits of the specific compound.

• Good ozone resistance.

• Good resistance to atmospheric aging.

• Suitability for selected static sealing applications.

• Electrical insulating properties characteristic of many silicone compounds.

Limitations of Silicone Rubber

Silicone is not a universal sealing material.

Compared with many NBR compounds, silicone rubber may have lower resistance to:

• Tearing.

• Abrasion.

• Mechanical damage during installation.

• Wear under dynamic friction.

Not all VMQ compounds are suitable for continuous contact with oils, fuels, solvents or aggressive chemicals.

Applications involving substantial friction or continuous movement require particular attention.

Operating Temperature of VMQ Silicone O-rings

Many standard VMQ silicone compounds have an indicative operating temperature range of approximately -50 to +200 degrees C.

However, this is a general characteristic of the silicone rubber material family, not a verified operating temperature specification for the exact GRN 21x3 VMQ 70 Shore A O-ring.

The actual permissible temperature range depends on:

• Silicone compound formulation.

• Sealed medium.

• Duration of temperature exposure.

• Mechanical loading.

• Required service life.

A maximum temperature of +200 degrees C should not be treated as a guaranteed product specification without supporting material documentation.

Silicone VMQ vs NBR O-rings

A silicone O-ring is not automatically interchangeable with an NBR O-ring of identical dimensions.

Material selection must account for the operating medium, temperature, pressure and type of movement.

Typical Applications of 21x3 Silicone O-rings

Silicone O-rings with a 3 mm cross-section may be used in appropriately designed:

• Static housing connections.

• Equipment covers.

• Technical instruments.

• Assemblies exposed to temperature variations.

• Selected industrial sealing systems.

• Laboratory equipment.

• Mechanical devices requiring elastomeric sealing.

These are examples of applications for the material and seal design, not confirmed OEM applications for the specific GRN product.

Silicone material alone does not establish approval for food contact, drinking water, medical devices or pharmaceutical applications.

Such uses require appropriate documentation and certification for the specific compound and finished product.

Static and Dynamic Sealing Applications

Static Sealing

The VMQ 70 Shore A O-ring may be used in appropriately designed stationary connections where sealing is achieved through controlled compression.

Examples include axial and radial static sealing arrangements.

Dynamic Sealing

The use of silicone rubber in applications involving relative movement requires careful evaluation.

Important factors include:

• Movement speed.

• Friction.

• Lubrication.

• Contact pressure.

• Abrasion resistance.

• Risk of twisting or mechanical damage.

For intensive dynamic operation, other elastomer materials or specialized sealing designs may be more suitable.

How to Select a 21x3 VMQ 70 Shore A O-ring

Before purchasing, verify:

1. Nominal inside diameter of 21 mm.

2. Cross-section diameter of 3 mm.

3. VMQ silicone material.

4. Hardness of 70 Shore A.

5. Seal groove geometry.

6. Required compression.

7. Permissible installation stretch.

8. Operating pressure.

9. Operating temperature.

10. Chemical compatibility with the sealed medium.

11. Static or dynamic operating conditions.

12. Required material certifications.

13. Required number of packs.

Identical dimensions of 21x3 mm do not guarantee complete interchangeability between O-rings made from different elastomers.

Installation and Storage

Before installation, clean the groove and mating surfaces.

Protect the silicone O-ring from sharp edges and excessive stretching.

During installation, avoid:

• Twisting the ring.

• Cutting or scratching the surface.

• Excessive compression.

• Using chemically incompatible assembly lubricants.

• Installing the ring into a damaged groove.

Silicone sealing rings should be stored in a clean, dry environment, protected against contamination and mechanical damage.

Alternative Designations and Reference Terms

The product may also be identified using the following designation formats:

• GRN O-ring 21x3 VMQ 70 Shore A

• O-ring VMQ 21x3 mm 70 Shore A

• O-ring MVQ 21x3 70 ShA

• Silicone O-ring 21x3 mm

• Silicone rubber sealing ring 21x3

• 21 mm ID 3 mm cross-section silicone O-ring

• GRN 21x3 silicone O-ring

• Silicone O-ring 21x3 100 pcs

• VMQ 70 O-ring 21x3 mm

VMQ and MVQ are used to identify silicone elastomer materials, but technical selection must still account for the specific compound formulation.

These designation formats are not confirmed OEM numbers or approved cross-references.

Frequently Asked Questions

What are the dimensions of the 21x3 silicone O-ring?

The nominal inside diameter is 21 mm and the cross-section diameter is 3 mm. The calculated nominal outside diameter is 27 mm.

What does VMQ mean?

VMQ is the internationally recognized designation for methyl vinyl silicone rubber, an elastomer commonly used in sealing applications.

What does 70 Shore A mean?

It indicates the nominal hardness of the silicone rubber according to the Shore A scale. This affects deformation and sealing behavior under compression.

How many O-rings are included in one pack?

One pack contains 100 individual GRN 21x3 VMQ 70 Shore A O-rings.

Is a silicone O-ring resistant to high temperatures?

Many silicone compounds offer good elevated-temperature resistance. However, the exact permissible operating temperature must be confirmed for the specific material formulation.

Can a VMQ O-ring be used with oil?

Suitability depends on the oil type, temperature and specific silicone compound. Chemical compatibility should be verified before use.

Is this silicone O-ring food-safe?

Silicone rubber alone does not guarantee food-contact approval. Appropriate documentation is required for the specific compound and finished product.

Can a 21x3 NBR O-ring be replaced with a 21x3 silicone O-ring?

Not automatically. Although the dimensions are identical, the materials differ in chemical resistance, mechanical properties and temperature performance.

O-ring 21x3 VMQ 70 Shore A - Key Technical Information

GRN O-ring 21x3 VMQ 70 Shore A is a silicone rubber sealing ring with a nominal inside diameter of 21 mm, a cross-section of 3 mm and a calculated outside diameter of 27 mm. Its nominal hardness is 70 Shore A. Primarily intended for appropriately designed static seals, it is supplied in packs containing 100 pieces.

GRN Silicone O-rings at simmering.pl

simmering.pl supplies VMQ silicone O-rings, NBR, FKM and EPDM sealing rings, rotary shaft oil seals and other industrial sealing components for machinery manufacturers, maintenance departments and technical service providers.

The 100-piece pack is suitable for technical purchasing, maintenance planning and maintaining a stock of sealing components with consistent nominal dimensions and material specifications.

Our warehouse is located in Lublin, Poland. We serve customers throughout the European Union and international markets, with worldwide shipping.