Tips to avoid rubber seals from failing due to excessive compression
Rubber seals are widely employed in a variety of industries, including automotive, aircraft, petrochemicals, and medical devices. The primary purpose is to prevent fluid or gas leaks and safeguard the equipment from external contamination. Rubber seals frequently experience severe compression during operation, resulting in performance degradation or even failure.
1. Causes of failure of rubber seals due to excessive compression
1.1 Material properties
Rubber materials have great elasticity and compressibility, but their elastic modulus is low, and they are prone to permanent deformation when compressed for an extended period of time or excessively. This distortion causes the seal to lose its original elasticity and become unable to recover its original shape, reducing the sealing function.
1.2 Improper design
Overcompression can also occur if the seal's design size does not correspond to the installation groove. Excessive seal cross-sectional area or insufficient installation groove depth can cause over-compression during installation, leading to stress concentration and material fatigue.
1.3 Installation error
During the installation process, incorrect operation or excessive installation force may cause the seal to compress excessively.
Furthermore, the selection and use of installation equipment will impact the seal's compression state.
1.4 Environmental factors
Environmental elements such as temperature, pressure, and chemical media all have an impact on rubber seal performance. High temperatures accelerate the aging of rubber materials and impair elasticity; high pressure increases the seal's compressive stress; and certain chemical media may cause the rubber material to swell or soften, increasing the effects of excessive compression.
2. Tips to avoid excessive compression failure of rubber seals
2.1 Reasonable selection of materials
Choosing the appropriate rubber material for the given application environment is the first step in avoiding excessive compression failure. Nitrile rubber (NBR), fluororubber (FKM), silicone rubber (VMQ), and ethylene propylene rubber (EPDM) are among the most often used rubber materials. Each material has distinct physical and chemical qualities, and should be decided based on the operating temperature, pressure, and media type.
- Nitrile rubber (NBR) is suitable for petroleum-based oils and fuels, as it has good oil and wear resistance.
- Fluororubber (FKM): Exhibits good high temperature and chemical corrosion resistance, making it ideal for high temperature and strong corrosion environments.
- Silicone rubber (VMQ) is excellent at both high and low temperatures, making it appropriate for a wide range of applications.
- Ethylene propylene rubber (EPDM) is weather and ozone resistant, making it ideal for use in outdoor and humid situations.
2.2 Optimized design
The seal's design should take into account both its functioning conditions and the installation environment. Here are some recommendations for design optimization:
- Compression rate control: The seal's compression rate should be kept within a reasonable range, often 15% to 30%. A high compression rate will cause the seal to be over-compressed, whilst a low compression rate may result in poor sealing.
- Installation groove design: The size of the installation groove should correspond to the seal to guarantee that the seal is evenly pressured after installation. To calculate the groove depth and width, consider the seal's compression rate and cross-sectional area.
- Stress distribution: Optimize the seal's shape and structure to ensure that stress is evenly distributed during compression, avoiding local stress accumulation.
2.3 Precise installation
Use special installation equipment to ensure that the seal is evenly stretched during installation, avoiding local over-compression.
Control the installation force: During the installation process, the installation force should be managed to avoid excessive force, which could result in excessive seal compression.
Check the installation quality: Once the installation is complete, inspect the seal to ensure that there is no distortion, deformation, or local over-compression.
2.4 Environmental control
In practical applications, the effect of external influences on the seal should be minimized as much as feasible. Here are some recommendations for environmental control.
Temperature management: In high-temperature situations, use high-temperature resistant rubber materials and use cooling techniques to minimize the seal's operating temperature.
Pressure control: In high-pressure situations, use high-strength rubber materials and design the seal to handle greater pressures.
Chemical medium protection: In extremely corrosive media, use chemically resistant rubber materials, and check the seals' status on a regular basis, replacing broken seals as needed.
2.5 Regular maintenance
Regular maintenance and inspections are essential for ensuring the seal's long-term and stable performance. Here are a few maintenance suggestions:
Regular inspection: Check the seal's condition on a regular basis, including its flexibility and the presence of cracks or deformations on the surface, among other things.
Timely replacement: If the seal shows signs of over-compression or aging, it should be changed promptly to minimize equipment failure due to seal failure.
Record and evaluate: Keep track of the seal's use and replacement cycle, study the causes of failure, and use as a reference for future selection and design.
3. Case analysis
3.1 Automobile engine seals
Rubber seals are used in automotive engines to stop oil and coolant leaks. A certain vehicle company used nitrile rubber seals in engine design, but the seals tended to over-compress and age in high temperature settings. This problem was effectively overcome by improving the design, using high-temperature resistant fluororubber materials, and managing the compression rate after installation, resulting in increased engine reliability and service life.
3.2 Chemical pump seals
Rubber seals are used in chemical pumps to keep the media from leaking. When a chemical facility used EPDM seals, it was discovered to have issues with over-compression and expansion in a strong acid environment. By switching to chemically resistant fluororubber materials and refining the installation groove design, the seals' over-compression failure was effectively prevented, ensuring the chemical pump's safe operation.
4. Conclusion
Rubber seals are crucial in industrial applications, however failure due to excessive compression cannot be overlooked. Rubber seals can be efficiently prevented from failing due to excessive compression by using appropriate materials, optimizing design, precise installation, controlling environmental conditions, and performing regular maintenance.
