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            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 both piston or rod applications. Urethane U-cups, commonly known as Disogrin U-cups, work well in both static and dynamic applications.



Profiles

Rod Single Lip Unloaded U-Cup

The rod style unloaded U-cup was 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

The rod style unloaded U-cup is available in a double lip design. The secondary “bump” or lip on the inside heel of the seal provides additional stability in the seal groove. The increased stability enhances the long-term performance of the seal. In rod seal leakage test, the double-lipped rod style unloaded U-cup had better performance then the conventional U-cup. This is due to the initial leakage of the seal is being reduced by the secondary sealing lip.


Symmetrical Unloaded U-Cup

This design provides satisfactory service for most rod and piston sealing applications. For more demanding applications with higher temperatures and pressure, other designs should be considered.

Piston Unloaded U-Cup

The piston style unloaded U-cup was 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 profile fits a standard u-cup gland, while providing increased extrusion resistance.



Design Considerations:


Surface Finish

The chart below provides 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 seal integrity. The unloaded urethane U-cup is designed to operate between 0 to 250 feet per minute at 1000-3500 psi. However, the unloaded U-cup can operate at up to 900 feet per minute in low or negligible system pressures. The unloaded urethane U-cup’s performance varies depending on temperature, lubrication, and the chemical environment. Performance capabilities can be extended with the use of an anti-extrusion ring.