O-rings: A comprehensive analysis of hardness application characteristics

O-rings are a common and widely used sealing element. Their working principle is to use their own elasticity and compression deformation to achieve sealing effects. O-rings are widely used, from daily necessities to complex industrial machinery. When selecting and using O-rings, hardness and application characteristics are three important considerations. Let's analyze these aspects in detail.

1. Hardness

The hardness of O-rings is generally expressed by the internationally accepted Shore A hardness (Shore A), which is quantified by numbers. The choice of hardness depends on the application environment and sealing requirements of the O-ring. Generally speaking, the higher the hardness of the O-ring, the better its anti-extrusion performance is, and it is suitable for high-pressure environments; while the lower hardness of the O-ring has better sealing and buffering effects, and is suitable for occasions that require soft sealing.

Low hardness (30-50 Shore A): Suitable for sealing occasions that require large deformation to absorb pressure or irregular surfaces.

Medium hardness (60-80 Shore A): The most widely used, suitable for most standard sealing occasions.

High hardness (90 Shore A and above): Suitable for high pressure or occasions that require extremely high mechanical strength.

2. Pressure

O-rings are generally less affected by pressure.

3. Application characteristics

The application characteristics of O-rings mainly involve factors such as working medium, working temperature and physical environment.

Working medium: Different working media have specific requirements for the material of O-rings. For example, when in contact with oily media, NBR nitrile rubber O-rings are usually selected; while in chemical media such as acids and alkalis, EPDM ethylene propylene diene monomer rubber is a better choice.

Working temperature: It is crucial to choose the right material according to the temperature range of the working environment. For example, silicone rubber is suitable for extreme temperature ranges from -60℃ to 300℃, while nitrile rubber performs well between -40℃ and 120℃.

Physical environment: Other physical environmental factors should also be considered, such as wear, UV exposure, etc., which will also affect the selection and service life of O-rings.

4. O-rings of different types of materials and their hardness

Different materials have different characteristics and application ranges. Here are some common materials and their hardness ranges:

Nitrile rubber (NBR):

Hardness range: 40-90 Shore A

Features: Good oil resistance, suitable for oil media and medium temperature environments.

Applications: Automobiles, hydraulic systems, oil and gas industries.

Ethylene propylene diene monomer (EPDM):

Hardness range: 30-90 Shore A

Features: Good weather resistance, heat resistance and chemical resistance, suitable for outdoor and high temperature environments.

Applications: Construction, automobiles, chemical equipment.

Silicone rubber (VMQ):

Hardness range: 20-80 Shore A

Features: Wide temperature resistance range, suitable for extremely low and extremely high temperature environments.

Applications: Aerospace, medical equipment, food industry.

Fluororubber (FKM):

Hardness range: 50-90 Shore A

Features: Excellent high temperature resistance, chemical resistance and oil resistance, suitable for harsh chemical environments.

Applications: Chemical, oil and gas, aerospace.

Polyurethane (PU):

Hardness range: 70-95 Shore A

Features: High mechanical strength, good wear resistance, suitable for high pressure and high wear environment.

Application: hydraulic system, engineering machinery.

Fluorosilicone rubber (FSI):

Hardness range: 40-80 Shore A

Features: Good oil resistance and weather resistance, suitable for high temperature and oil medium environment.

Application: aerospace, oil and gas.

Summary

Choosing a suitable O-ring requires comprehensive consideration of factors such as hardness and application characteristics. Different materials have different characteristics and application ranges, so in specific applications, the appropriate O-ring should be selected according to the requirements of the working environment and medium. If you have specific application needs, it is recommended to consult a professional O-ring supplier or engineer for more detailed and professional guidance.

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