Enhancing Performance and Safety of Static Radial Seals
O-ring and back-up ring combinations have long been the standard for static applications requiring high-pressure sealing. However, real-world applications often expose limitations, including installation challenges and performance issues. Standard O-rings may twist during installation, while back-up rings can be incorrectly positioned or damaged. These issues are further compounded by exposure to pulsating pressures and contaminants, which can reduce reliability.
To address these challenges, Parker has introduced the HS seal profile—a robust alternative to conventional O-ring and back-up ring setups for static, high-pressure applications. The HS seal features a symmetrical design and is crafted from highly extrusion-resistant Parker polyurethane compounds. This innovative design not only simplifies installation but also improves performance under pulsating pressure conditions, leading to significantly longer service life.
Key Benefits of the HS Seal
Compared to traditional O-ring/back-up ring combinations, the HS seal offers several advantages:
- Simplified installation process
- Elimination of twisting during installation
- Exceptional extrusion resistance due to advanced polyurethane materials
- Performance durability many times greater than standard O-rings
- Extended operational lifespan
- Compatibility with standard O-ring grooves designed for back-up rings
Finite Element Analysis Demonstrates Reliability
Finite element analysis (FEA) provides valuable insights into the HS seal's performance. Stress distribution and sealing pressure were analyzed under two conditions: at room temperature without pressure and at 600 bar with increased temperatures of 60°C. These analyses reveal the HS seal's robust compression areas and reliable sealing pressure distribution, even under high-pressure and high-temperature conditions.
One notable advantage of the HS seal is its dual sealing areas, which enhance protection against leakage. These sealing edge pairs also prevent twisting during both installation and operation, making the seal highly reliable under pulsating pressures, misaligned grooves, or breathing components.
Additionally, the HS seal eliminates the need for back-up rings thanks to the use of extrusion-resistant polyurethane, such as the P6000 compound with 94 Shore A hardness. Even under extreme conditions—600 bar of pressure and elevated temperatures—minimal extrusion is observed, simplifying installation and improving overall reliability.
Applications of the Ultrathan® HS Seal
The HS seal is ideal for static radial applications at high pressures, including:
- Hydraulic valves
- Hydraulic cylinders
- Machine tools
- Injection molding machines
- Other static sealing points requiring radial sealing
The original article can be found on Parker's website. It was contributed by Dr. Peter Kreißl, hydraulics market unit manager at Engineered Materials Group.
