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Content

            1. Unloaded Urethane U-Cup Size Charts
                        1. Imperial
                        2. Metric
            2. Unloaded Urethane U-Cup Description
            3. Profiles
            4. Design Considerations
                        1. Surface Finish
                        2. Pressure/Velocity
  


Jump to imperial unloaded U-cup sizes.
Jump to metric unloaded U-cup sizes.


Description

The urethane U-cup design provides an excellent heavy duty seal for either piston or rod applications. Urethane U-cups work well in both static and dynamic applications.



Profiles

Rod Single Lip Unloaded U-Cup

The rod style unloaded U-Cup is specially designed with a shorter, heavier inside sealing lip to achieve a higher initial sealing force on the tube. The rod style unloaded U-cup was developed to extend serviceability and improve reliability in rod sealing.

Rod Double Lip Unloaded U-Cup

Unloaded rod U-cup is available in a double lip design. The addition of a secondary “bump” on the inside heel of the seal provides added stability in the seal groove, which enhances the long term performance of the seal. This seal has proved to have better performance than conventional U-cups in rod seal leakage tests as the initial leakage of the seal is
reduced by the secondary sealing lip.

Symmetrical Unloaded U-Cup

The Symmetrical Urethane U-Cup has a u-shaped groove formed in such a manner that there is an inside and outside sealing lip. This design provides satisfactory service for most rod and piston sealing applications. For more demanding applications where temperatures and pressures are higher, you should consider one of the other designs.
Piston Unloaded U-Cup

The piston style unloaded U-cup is specially designed with a shorter, heavier outside sealing lip to achieve a higher initial sealing force on the tube. The piston style unloaded U-cup was developed to extend serviceability and improve reliability in piston sealing.
Piston Unloaded U-Cup with Anti-Extrusion Ring

Unloaded piston U-cups are also available with anti-extrusion rings. The specially designed profile fits a standard u-cup gland, while providing increased extrusion resistance.



Design Considerations:


Surface Finish

The chart below provides you with a general guideline on surface finish.

 Static
8-32 RMS
 Dynamic
16 RMS

Pressure/Velocity

Pressure and velocity are two of the factors that will affect your seal integrity. The unloaded urethane u-cup is designed to operate between 0 to 250 feet per minute at 1000-3500 psi, but can operate at up to 900 feet per minute in low or negligible system pressure. Performance varies depending on temperature, lubrication, and the chemical environment. Performance capabilities can be extended with the use of an anti-extrusion ring.