The environment plays a major role in the functionality of rubber o-rings. Every o-ring is designed with a specific material, hardness and shape to handle the application. Some applications may involve extreme heat, while others may require exposure to harsh chemicals that an o-ring must be able to handle.
To ensure o-ring success, preventative measures should be taken from the start of the design process. It’s important for design engineers to have all of the application requirements up front to ensure the seal will be compatible with its environment. Here’s a closer look at what you can do to prevent environmental factors from destroying your o-ring:
Materials must be chemically compatible with their environment.
Despite any critical design factors, every o-ring must be compatible with the chemicals and outside materials they’re exposed to. A lack of compatibility can cause o-rings to wear down, tear and eventually fail.
To prevent the environment from deteriorating your o-ring, design engineers should match your application with the o-ring material that can best handle the chemicals it will be exposed to. For example, butyl is chemically compatible with boric acid, but would fail if exposed to diesel oil. To test out the compatibility of your o-ring material, check out our Chemical Compatibility Guide.
Know the amount of pressure your seal can handle.
Pressure can have an unpleasant effect on o-rings, causing the cross section to distort. This distortion blocks the diametrical clearance gap between mating surfaces of the seal. When an o-ring cannot resist increasingly high pressure, part of the o-ring will be extruded into the diametrical gap, leading to premature failure, leakage and system contamination.
There are a few preventative measures you can take to reduce the risk of extrusion under pressure, including:
- Increase the o-ring hardness
- Use back-up o-rings to support the seal block the diametrical clearance gap
- Reduce the diametrical clearance gap between the mating surfaces
- Lower the pressure of the system if possible
Be aware of friction.
Friction is caused by continuously moving applications. O-Rings will rub against other moving materials while the application is running, which can have some harsh effects on the seal. While some seals are built to handle a long exposure to friction, others may experience o-ring swell, tears or failure.
To prevent friction from destroying your o-ring, there are a few factors to consider during the design phase:
- Cross section: o-rings with a smaller cross section will produce less friction
- Lubrication: seal adhesion can be minimized by proper lubrication
- Material selection: some materials can handle high amounts of friction, while others have a very low tolerance
- Groove width: increasing the groove width can create more room to expand perpendicular to the compressive force
Understand the effects of temperature.
Temperature has a major effect on the functionality of rubber seals. Some materials can handle extreme heat or cold, while others function best at room temperature. When a non-compatible seal is exposed to high heat over an extended period of time, the o-ring may degrade physically and chemically, which causes them to fail.
When it comes to extreme cold, non-compatible o-rings may experience shrinkage and possible leakage due to the reduction of surface contact. For optimum sealing performance, be sure to choose the right sealing material that can handle the environmental factors of your application.
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