Analysis of temperature and pressure limit values ​​of rubber sealing rings

1. Effect of temperature on the performance of rubber sealing rings

1.1 Effect of temperature changes on the performance of rubber materials

Rubber’s elasticity fluctuates according on the temperature. In general, higher temperatures cause rubber to become softer and more elastic. Rubber will become less elastic and harder as the temperature drops. Rubber that is exposed to low temperatures may break easily and lose its natural suppleness and elasticity.

Variations in temperature have a direct impact on the rubber’s hardness. Rubber will become softer and less rigid at high temperatures, whereas rubber will become more brittle and hard at low temperatures.

Volume variations: Temperature fluctuations will induce thermal expansion and cold contraction of the rubber. Cold contraction may result in the rubber sealing ring shrinking and losing its ability to seal, but thermal expansion may cause the rubber sealing ring to grow in size and lose its ability to seal.

Chemical stability: The rubber material will age and deteriorate more quickly at high temperatures because of the accelerated chemical reaction. Rubber, for instance, is more likely to cross-link or break down in an environment with high temperatures, diminishing its strength and flexibility and reducing its ability to seal.

1.2 Comparison of temperature resistance of different rubber materials

Natural rubber (NR): Typically working temperatures vary from -50°C to +70°C. Natural rubber has strong mechanical strength and flexibility, but it has low heat resistance. Natural rubber is prone to aging and damage in environments with high temperatures.

Nitrile rubber (NBR): This rubber can withstand temperatures ranging from -40°C to +120°C and has outstanding resistance to wear and grease. Its performance is quite steady in high temperature environments, but at low temperatures, it may harden and lose its elasticity.

EPDM (ethylene propylene rubber): EPDM is a rubber with a temperature range of -50°C to +150°C, making it appropriate for use in both high- and low-temperature situations. It also exhibits good resistance to weather and ozone.

Fluororruber (FKM): Suitable for extremely high temperature situations, fluororubber has an excellent resilience to high temperatures, with a temperature range of -20°C to +200°C. It may harden at low temperature conditions, although its low temperature performance is often poor.

Silicone rubber (VMQ): With a broad temperature resistance range and exceptional high and low temperature resistance, silicone rubber retains strong elasticity and sealing performance between -60°C and +200°C.

1.3 Specific effects of high and low temperatures on the performance of rubber sealing rings

Effects of high temperature

Aging and degradation: Rubber ages more quickly at high temperatures, which can lead to the material hardening, cracking, or losing its flexibility. For instance, natural rubber may oxidize and harden at high temperatures, which might impair its ability to seal.

Reduction of Elasticity: Rubber material will become softer at high temperatures. Long-term exposure to high temperatures will degrade the material’s structure, severely lower its elasticity, and weaken the sealing effect—despite the possibility that it will improve elasticity in the short term.

Volume change: The sealing ring’s size may expand due to thermal expansion brought on by a high temperature, which may impact how well it fits the sealing surface and result in leaks.

Effects of low temperature

Hardening and embrittlement: Rubber materials have a tendency to lose their natural elasticity and flexibility when exposed to low temperatures. For instance, the sealing ring may fail at low temperatures due to nitrile rubber’s tendency to harden.

Elasticity reduction: Low temperatures cause the rubber material’s molecules to move more slowly and lose some of their elasticity. This reduces the sealing ring’s ability to close tightly, raising the possibility of leaks.

Shrinkage and size change: The sealing ring may shrink due to cold shrinkage brought on by low temperatures, making it less able to make close contact with the sealing surface and less effective in sealing.

2. The effect of pressure on the performance of rubber sealing rings

2.1 The mechanism of pressure on the sealing effect of rubber sealing rings

The contact pressure between rubber sealing rings and the sealing surface determines how well they seal. The sealing ring fills the tiny irregularities on the sealing surface and fits the sealing surface snugly when it is inserted into the sealing groove and pressure is applied. This stops liquids or gas from leaking.

Compression deformation and stress distribution comprise the two primary components of the pressure mechanism on rubber sealing rings. The distortion of the rubber sealing ring under pressure is known as compression deformation. The sealing effect is enhanced by this distortion because it expands the region of contact between the sealing ring and the sealing surface. Whether or not there is consistent pressure on the sealing ring in various places affects the distribution of stress. The overall sealing performance may be impacted by uneven stress distribution, which can lead to stress accumulation in specific parts of the sealing ring.

2.2 Pressure resistance of different rubber materials

Rubber materials come in a variety of forms, and their resistance to pressure varies as well. For instance, because of its excellent elasticity and mechanical qualities, natural rubber (NR) is appropriate for use in a variety of low- to medium-pressure applications. Because of its superior oil and pressure resistance, nitrile rubber (NBR) is better suited for high-pressure settings like hydraulic systems. Since fluororruber (FKM) offers great resistance to high temperatures, chemicals, and pressures, it has become the material of choice for sealing under harsh conditions. In addition to having strong heat and pressure resistance, chloroprene rubber (CR) is appropriate for settings with high temperatures and chemical corrosion.

2.3 Effect of long-term pressure on the life of rubber seals

Rubber seals’ lifespan is greatly impacted by sustained pressure. Rubber seals may permanently distort due to compression under continuous pressure; this will lessen the seals’ flexibility and impair their ability to seal. Furthermore, rubber ages more quickly and performs worse over time due to fatigue from repeated strain on rubber components.

3. Temperature limit of rubber seals

3.1 Definition of temperature limit of rubber seals

The maximum and lowest temperatures that rubber seals can tolerate are referred to as the temperature limit; within this range, the seals can retain their physical characteristics and sealing ability. When the rubber material ages, softens, hardens, or dissolves beyond this point, sealing effectiveness may suffer or perhaps fail.

The rubber material’s temperature resistance, which is influenced by the seal’s design, usage environment, and operational circumstances, often establishes the temperature limit. As a result, in order to determine the rubber seal’s temperature limit, all of these parameters must be taken into account.

3.2 Analysis of temperature limits of common rubber materials

Natural rubber (NR): Typically appropriate for temperatures between -60°C and +100°C, this material has high flexibility and resilience to wear.
SBR (styrene-butadiene rubber) has a low oil resistance but a temperature resistance that is comparable to natural rubber.
Nitrile rubber (NBR): Suitable for temperatures between -40°C and +120°C, it has strong chemical and oil resistance.
Silicone rubber (Si): Capable of withstanding temperatures between -100°C and +250°C, it has exceptional resilience to both high and low temperatures.
Fluororruber (FKM): Suitable for temperatures between -20°C and +200°C or higher, it has exceptional resilience to high temperatures, oils, and chemicals.
Chloroprene rubber (CR) is appropriate for temperatures between -30°C and +120°C due to its strong resistance to heat, ozone, and weathering.

3.3 The impact of temperature limits on the selection of rubber seals

Working environment: Choose a rubber material that can withstand a variety of temperatures based on the seal’s working environment temperature.

Performance criteria: The performance requirements for seals vary depending on the application, thus it’s important to choose the right rubber material for the job.

Long-term stability: To guarantee the long-term dependability of the seal, choose a rubber material that can continue to work steadily for the duration of the anticipated service life.

4. Pressure limit of rubber seals

4.1 Definition of pressure limit of rubber seals

The highest pressure that a rubber seal can bear without failing or significantly degrading its performance is referred to as the pressure limit. The physical characteristics of the rubber material, the seal’s design, and the application environment often dictate this limit. Overpressurizing the rubber seal can result in permanent distortion from compression, rupture, or other types of damage that can harm the seal and cause sealing failure.

4.2 Analysis of pressure limits of common rubber materials

Natural rubber (NR) is a desirable choice for low to medium pressure applications because of its good mechanical qualities and flexibility.
Because of its superior resistance to pressure and oil, nitrile rubber (NBR) is a good fit for high pressure hydraulic systems.
Fluororruber (FKM) is a great material for applications requiring high pressure because of its exceptional chemical, temperature, and pressure resistance.
Chloroprene rubber (CR) is a strong choice for applications involving medium pressure range because to its good resistance to weather aging and pressure.
Silicone rubber (Si): It performs well as a sealant within a specific pressure range, although it is more resilient to high and low temperatures.
The manufacturer’s data and the particular product specifications must be used to establish the pressure limitations of these materials.

4.3 The impact of pressure limits on rubber seal design

Seal size: To sustain larger pressures, the seal’s cross-sectional size may need to be increased, or the groove design may need to be modified.
Material selection: To guarantee the pressure resistance of the seal, the right rubber material must be chosen throughout the design process based on the anticipated pressure range.
Safety factor: During long-term operation, a safety factor is often taken into account during design to guarantee that the seal can continue to function properly during pressure changes.
Performance testing: In order to confirm that the seal ring satisfies the pressure limit specifications, it must be pressure tested during the design phase.
Maintenance and replacement: Knowing the pressure limit is helpful in creating plans for maintenance and replacement methods that prevent seal failure brought on by going over the pressure limit.

5. Application environment analysis of rubber seal rings

5.1 Temperature and pressure conditions in different industrial applications

Automotive industry: Rubber seal rings must endure high temperatures and high pressures in engines, gearboxes, and other components.
Aerospace: In this sector, seal rings must continue to function in the face of extremely high and low temperatures as well as high air velocity impacts.
Chemical industry: Rubber seal rings must be able to withstand chemical deterioration when exposed to chemical media.
Petroleum industry: Seal rings must endure high pressure and conditions containing corrosive compounds during drilling and mining.
Food processing: Rubber seal rings used in this sector must be able to endure high temperatures during sterilization and adhere to food safety regulations.

5.2 Select suitable rubber seal rings according to the application environment

Temperature range: Choose rubber materials with matching temperature resistance based on the application environment’s greatest and lowest temperatures.
Pressure level: Choose seal ring designs and materials that can resist the relevant pressure based on the system’s needs.
Chemical compatibility: To prevent performance deterioration brought on by chemical interactions, take into account the seal ring’s compatibility with the contact medium.
Mechanical strength: Choose rubber materials that are resilient to mechanical stress and have enough flexibility.
Durability: Choose rubber seal rings that will continue to function for the duration of their anticipated service life.

5.3 Comprehensive consideration of environmental factors on the performance of rubber seal rings

The combined impact of temperature and pressure: Rubber seal rings may encounter high temperatures and high pressures simultaneously in some applications, necessitating the strong overall performance of the seal ring material.
Chemical media influence: Rubber aging, hardening, or softening due to prolonged exposure to certain chemicals might have an impact on sealing effectiveness.
Applications that are both dynamic and static: In dynamic applications, rubber seal rings must endure frequent deformation and friction, but in static applications, the seal ring’s long-term stability is more important.
Environmental humidity: Particularly in tropical or coastal regions, humidity may have an impact on the longevity and rate of aging of rubber.