Introduce
Rubber seals are essential to many sectors, but they are particularly important in the automotive, chemical, aerospace, and food and beverage industries where they are frequently employed to stop liquid and gas leaks. The permeation phenomena influence production efficiency and product quality in addition to sealing performance. It may also result in equipment damage or product contamination.
The reasons behind gas permeation, typical contributing elements, and practical solutions to the issue will all be covered in depth in this article.
What is gas permeation?
The passage of gas molecules through solid materials (like rubber) is referred to as gas permeation. This implies that, in the case of rubber seals, certain gas molecules may progressively pass through the rubber material and either enter the sealed compartment or exit it. The seal cannot entirely stop the gas because gas molecules are smaller than liquid molecules and can more readily pass through elastomeric materials like rubber.
Common types of gas permeation
- Diffusion: The primary method of permeation in rubber materials is the movement of gas molecules inside them.
- Adsorption: Before entering the substance, gas molecules are first adsorbed on the rubber surface.
- Desorption: Gas molecules leave the substance and enter the surrounding air after being desorbed from the opposite side.
Impact of gas permeation problems
- Leakage: Gas leaks can happen when rubber seals are unable to stop gas from penetrating, putting the equipment's safety in jeopardy, particularly in high-pressure or hazardous gas situations.
- Pressure loss: Permeation makes it impossible for the system's internal pressure to stay at the desired level, which interferes with the system's ability to function normally.
- Pollution: Gas penetration has the potential to contaminate the internal medium by introducing outside gas into the enclosed environment. This pollution will have a direct impact on the quality of the products, particularly in areas like food and medicine where strict cleanliness regulations apply.
- Equipment damage: Extended gas penetration can limit the equipment's service life by causing wear or corrosion on its components.
Factors affecting gas permeation
Selection of rubber materials
Rubber materials vary in their behavior when exposed to gas penetration. In general, gas permeation is easier when gas molecules are smaller. Examples of gases that are more challenging to stop are hydrogen and helium. Nitrile rubber (NBR) and chloroprene rubber (CR) perform better against gas penetration than silicone rubber and fluororruber (FKM), two of the most widely used rubber compounds.
Temperature and pressure
The movement of gas molecules is accelerated in high-temperature and high-pressure environments, leading to quicker penetration rates. Rubber materials become more flexible as the temperature rises, making it easier for gas molecules to pass through them.
Types of gas
Because molecule size and structure vary, various gases penetrate at varying rates. Large molecular gases, such as carbon dioxide and fluorinated gases, have poor permeability, whereas tiny molecule gases, like oxygen and hydrogen, have great permeability.
Effective measures to solve the problem of gas permeation
Optimize the selection of rubber materials
The selection of rubber materials should be based on the actual circumstances of use. Rubber materials having low gas permeability, such as ethylene propylene rubber, fluorocarbon rubber, etc., might be chosen for situations where high temperatures and pressures are required. Furthermore, rubber materials enhanced by unique formulations might lessen gas penetration even further.
Coating treatment
An efficient method is to apply a barrier coating on the rubber seals' surface. The rate at which gases permeate this layer can be considerably decreased. For instance, metal plating or PTFE coating can improve rubber materials' capacity to act as gas barriers, which in turn improves seals' resistance to penetration.
Reduce the temperature and pressure in the environment
The rate of gas penetration can be slowed down by reducing the temperature and pressure in the area around the seal. Reasonable structural design can minimize the possibility of excessive force on the seal during the design phase.
Increase the thickness of the seal
One popular technique to stop gas penetration is to make the rubber seal thicker. The gas molecules in the material travel farther as thickness rises, hence decreasing the penetration rate.
Regular inspection and maintenance
Check the rubber seal on a regular basis to identify possible issues early on that may arise from gas infiltration. Equipment failure or leakage due to penetration can be avoided by replacing old seals.
Conclusion
Rubber seals frequently experience gas penetration in real-world applications, however, the detrimental effects of gas penetration may be significantly mitigated with appropriate material selection, structural design, and maintenance protocols. In an environment where sealing is in high demand, knowing the reasons behind penetration and how to prevent it helps prolong the equipment's life while simultaneously increasing production efficiency and guaranteeing product quality.
