O-ring 35x4 VMQ 70 ShA - Silicone

O-ring 35x4 VMQ 70 ShA - Technical Characteristics

The 35x4 VMQ 70 ShA O-ring is an elastomeric sealing element with a circular cross-section.

Unlike radial shaft oil seals, an O-ring does not incorporate a dedicated sealing lip, metal housing or garter spring.

Its sealing function is based on elastic deformation within a correctly designed groove. Compression of the cross-section generates contact pressure against the mating surfaces.

The specified material is silicone rubber VMQ with a nominal hardness of 70 Shore A.

For correct identification, the following characteristics must be considered together:

• Inside diameter: 35 mm

• Cross-sectional diameter: 4 mm

• Material: VMQ silicone rubber

• Nominal hardness: 70 Shore A

• Package quantity: 100 pieces

O-ring 35x4 mm - Dimensions

The dimensional designation 35x4 mm identifies the nominal inside diameter and cross-sectional diameter.

The nominal outside diameter is calculated using:

OD = ID + 2 x CS

OD = 35 + 2 x 4 = 43 mm

This is a geometrically calculated nominal value, not an independently measured dimension of the finished product. Actual dimensions are subject to manufacturing tolerances.

Construction of the 35x4 Silicone O-ring

The O-ring has a continuous annular shape with a circular cross-section.

Before installation, the cross-section is nominally round. When installed in a suitable groove, the elastomer undergoes controlled deformation, producing contact pressure against the mating surfaces.

Sealing performance depends on several factors:

• Cross-sectional compression, also known as squeeze

• Groove geometry and gland fill

• Circumferential stretch or compression

• Surface finish of mating components

• Operating medium

• Temperature and pressure

• Material properties and dimensional tolerances

The nominal 35 mm inside diameter alone does not determine the required groove dimensions.

The groove must be designed according to the sealing arrangement and operating conditions.

VMQ / MVQ - Silicone Rubber Material

VMQ is the standard technical designation for a class of silicone rubber elastomers. MVQ is also encountered as a commercial material designation.

VMQ silicone rubbers are generally associated with good low-temperature flexibility and resistance to ozone and weathering.

However, mechanical properties, chemical resistance and permissible operating temperatures depend on the specific compound formulation.

The designation VMQ 70 ShA does not establish every performance characteristic of this particular O-ring.

In particular, the material designation alone does not confirm:

• Food-contact approval

• Medical-grade certification

• Compatibility with every oil, fuel or solvent

• A specific maximum operating temperature

• A particular pressure rating

Such properties require compound-specific documentation or appropriate testing.

What Does 70 Shore A Mean?

70 ShA identifies the nominal hardness of the silicone elastomer on the Shore A scale.

Hardness influences the deformation behaviour of an O-ring under compression and is relevant to sealing contact, installation and extrusion resistance.

A silicone O-ring with a nominal hardness of 70 Shore A should not automatically be replaced with a 50, 60 or 80 Shore A version, even when the nominal dimensions are identical.

Changing hardness may require reassessment of groove geometry and operating conditions.

O-ring 35x4 VMQ - Selection and Interchangeability

When selecting a replacement O-ring, verify the following characteristics:

1. Nominal inside diameter: 35 mm.

2. Nominal cross-sectional diameter: 4 mm.

3. Elastomer material: VMQ silicone rubber.

4. Nominal hardness: 70 Shore A.

5. Required dimensional tolerances.

6. Compatibility with the operating medium.

7. Temperature, pressure and sealing arrangement.

An O-ring 35x4 NBR 70 ShA is not automatically interchangeable with an O-ring 35x4 VMQ 70 ShA.

Although both may have identical nominal dimensions and hardness, NBR and VMQ differ in their chemical, mechanical and thermal properties.

The same applies to O-rings manufactured from FKM, EPDM and other elastomer compounds.

Dimensional similarity alone does not establish full technical interchangeability.

Technical Specification

FAQ - O-ring 35x4 VMQ 70 ShA

1. What are the dimensions of the O-ring 35x4 VMQ 70 ShA?

The nominal inside diameter is 35 mm, and the cross-sectional diameter is 4 mm. The calculated nominal outside diameter is 43 mm.

2. What does VMQ mean in an O-ring designation?

VMQ identifies silicone rubber in technical elastomer nomenclature. MVQ is also encountered as a commercial designation for silicone rubber.

3. What does 70 ShA mean?

It indicates a nominal elastomer hardness of 70 Shore A.

4. Can a 35x4 VMQ O-ring be replaced with an NBR O-ring?

Not without verifying the operating conditions. NBR and VMQ have different material properties, and identical dimensions and hardness do not guarantee interchangeability.

5. Is the 35x4 VMQ O-ring suitable for high temperatures?

VMQ silicone rubbers can be used in elevated-temperature applications, but the permissible operating temperature of this specific product requires confirmation from the compound manufacturer or supplier.

6. Is the silicone O-ring 35x4 suitable for food contact?

The designation VMQ 70 ShA does not itself confirm food-contact compliance. Appropriate documentation for the specific compound and finished product is required.

7. How should a groove for a 35x4 O-ring be designed?

Groove design must consider the 4 mm cross-section, required squeeze, gland fill, dimensional tolerances and operating conditions. The calculated 43 mm outside diameter alone is insufficient to determine groove dimensions.

8. How many O-rings are included in one package?

Each package contains 100 silicone O-rings 35x4 VMQ 70 ShA.

AI Overview

O-ring 35x4 VMQ 70 ShA - 100 pcs. is a silicone rubber sealing ring with a nominal inside diameter of 35 mm and a cross-sectional diameter of 4 mm. Manufactured from VMQ silicone elastomer with a nominal hardness of 70 Shore A, it forms a seal through controlled compression. Its calculated nominal outside diameter is 43 mm.