Are you looking for a reliable sealing solution for your hydraulic or pneumatic system? If so, you may want to consider using rubber backup sealing rings. These rings are designed to prevent extrusion in rubber o-ring sealing systems, which can be a common issue in high-pressure applications. By providing a barrier between the o-ring and the extrusion gap, backup rings help to extend the life of the o-ring and improve its performance.
Rubber backup sealing rings are made from either PTFE or rubber, with each material offering its own unique benefits. PTFE backup rings are typically used in high-pressure applications where extrusion resistance is critical, while rubber backup rings are more commonly used in dynamic sealing applications. There are three basic types of PTFE backup rings in use: single turn (scarf cut), multiturn (spiral cut), and solid (uncut) configurations. Rubber backup rings, on the other hand, are called contoured backup rings and are designed to fit between the o-ring and the extrusion gap.
Overview of Rubber Backup Sealing Rings
Rubber backup sealing rings are essential components in sealing systems that work in conjunction with o-rings. These rings fit into a groove or gland of a seal, where their distinct shape and rigidity prevent the o-ring from entering the clearance gap during high-pressure operations. Backup rings are robust, hardened rings that support the o-ring and prevent it from extrusion. In this section, we will discuss the material composition, function, and application of rubber backup sealing rings.
Material Composition
Rubber backup sealing rings are typically made from materials such as PTFE or rubber. Contoured backup rings are made from rubber, while PTFE backup rings come in three basic types: single turn (scarf cut), multiturn (spiral cut), and solid (uncut) configurations. The material composition of backup rings is critical because it affects their performance in various operating environments. For instance, Parker's MB back-up rings are formulated with high modulus blends of Molythane and Polymyte, making them suitable for use with either type of base sealing material while maintaining the expected temperature range and fluid compatibility.
Function and Application
The primary function of rubber backup sealing rings is to prevent extrusion in rubber o-ring sealing systems. They are used in high-pressure applications where the o-ring is subjected to high stress and pressure, which can cause it to extrude into the clearance gap. Backup rings are also used to increase the sealing pressure and reduce the diametrical clearance of the sealing system. They can be used in conjunction with other sealing components such as o-rings, gaskets, and seals to provide a reliable and robust sealing solution.
Rubber backup sealing rings are used in a wide range of applications, including hydraulic and pneumatic systems, automotive engines, and industrial equipment. They are used in applications that require high-pressure sealing, such as hydraulic cylinders, pumps, and valves. Backup rings are also used in applications that require low friction and wear, such as rotary shaft seals and reciprocating seals.
In summary, rubber backup sealing rings are critical components in sealing systems that work in conjunction with o-rings. They are made from materials such as PTFE or rubber and are used in a wide range of applications that require high-pressure sealing or low friction and wear. The material composition of backup rings is critical because it affects their performance in various operating environments.
Design Specifications
Dimensional Standards
When designing rubber backup sealing rings, it is important to consider the dimensional standards that must be met. These standards ensure that the ring will fit properly and function as intended. The most important dimensions to consider are the inner diameter (ID), outer diameter (OD), and thickness. These dimensions are typically specified in the design drawings and must be followed closely during manufacturing.
The ID of the ring should be slightly smaller than the shaft it will be installed on, while the OD should be slightly larger than the housing it will be installed in. This ensures a tight fit that will prevent leaks. The thickness of the ring should be selected based on the amount of pressure the ring will be subjected to, as well as the material properties of the ring.
Tolerance Levels
Tolerance levels are another important consideration when designing rubber backup sealing rings. Tolerance levels determine how much variation is allowed in the dimensions of the ring. Tighter tolerance levels result in a more precise fit, but also increase the cost of manufacturing. Looser tolerance levels are less expensive, but may result in a less effective seal.
When selecting tolerance levels, it is important to consider the specific application of the ring. For example, rings used in high-pressure applications may require tighter tolerance levels than rings used in low-pressure applications. Additionally, the material properties of the ring may affect the tolerance levels that can be achieved.
Overall, careful consideration of the dimensional standards and tolerance levels is essential when designing rubber backup sealing rings. By following these guidelines, you can ensure that your rings will fit properly and provide effective sealing.
Installation Guidelines
Preparation Steps
Before installing a rubber backup sealing ring, it is important to ensure that the equipment is clean and free of debris. Any dirt or debris on the equipment can cause damage to the sealing ring, which can lead to premature failure.
Additionally, it is important to select the correct size and type of backup ring for the application. The backup ring should be slightly larger than the o-ring it is supporting, and should be made of a material that is compatible with the application.
Installation Techniques
To install a rubber backup sealing ring, follow these steps:
- Lubricate the o-ring and backup ring with a compatible lubricant. This will help the rings slide into place and prevent damage during installation.
- Place the o-ring into the groove or gland of the seal.
- Slide the backup ring over the o-ring and into the groove or gland. Make sure that the backup ring is seated properly and that it is not twisted or misaligned.
- Apply pressure to the backup ring to ensure that it is properly seated. This can be done using a tool or by hand.
- Check the clearance gap between the backup ring and the equipment. The clearance gap should be blocked by the backup ring to prevent the o-ring from entering the gap during high-pressure operations.
By following these installation guidelines, you can ensure that your rubber backup sealing ring is installed correctly and will provide reliable sealing performance.
Performance and Durability
When it comes to choosing a backup sealing ring, performance and durability are two crucial factors to consider. A backup ring should provide reliable sealing performance for an extended period of time, even in harsh environments.
Temperature Resistance
One of the most important factors affecting the performance of rubber backup sealing rings is temperature. These rings should be able to withstand a wide range of temperatures without losing their sealing properties. Some materials are better suited for high-temperature applications, while others are better suited for low-temperature applications.
For example, PTFE (Polytetrafluoroethylene) backup rings have excellent temperature resistance and can withstand temperatures ranging from -200°C to 260°C. On the other hand, Nitrile rubber backup rings have a lower temperature range of -40°C to 120°C.
Chemical Compatibility
Another important factor to consider when choosing a backup sealing ring is chemical compatibility. Backup rings should be made from materials that are resistant to the chemicals they will be exposed to in their intended application.
For instance, Viton backup rings are highly resistant to chemicals such as acids, fuels, and oils. PTFE backup rings, on the other hand, have excellent chemical resistance to most chemicals, including acids, bases, and solvents.
It's important to note that not all backup sealing rings are suitable for all chemicals. Therefore, it's essential to choose a backup ring that is specifically designed for the chemicals it will be exposed to in its intended application.
In summary, when choosing a rubber backup sealing ring, it's important to consider factors such as temperature resistance and chemical compatibility. By selecting a backup ring that is specifically designed for your application, you can ensure reliable sealing performance and extended durability.