The HS static radial seal made of polyurethane compounds was developed as an alternative to conventionally used O-ring/back-up ring combinations for static sealing applications at high pressures. The robust, symmetrical seal geometry and the utilization of particularly extrusion-resistant Parker polyurethane compounds not only facilitates installation but increases sealing performance in conditions of pulsating pressures as well, resulting in clearly longer service life.
The benefits of the HS seal result from the serial configuration of the two sealing areas, which doubles the protection against leakage compared to a single seal. In addition, with two sealing areas or sealing edge pairs backing up the seal, exceptional protection against twisting of the seal is achieved, both during installation and in operation at pulsating pressures, for instance in combination with breathing components and coaxiality defects of the groove.
The use of particularly extrusion-resistant materials, especially the P6000 polyurethane compound with 94 Shore A hardness, eliminates the need for back-up rings.

• Robust seal profile for harshest operating conditions.
• Insensitive to pressure peaks.
• High extrusion resistance.
• Excellent media resistance in case of suitable compound selection.
• Suitable compounds available for special requirements of the chemical process industry.
• Suitable compounds available for special requirements of the food processing industry.
• Installation in closed and undercut housings.
• Additional sizes of machined products available on short notice.

Range of application:
The HS Ultrathan® seal is suitable for radial, static applications at high pressures such as hydraulic valves and cylinders, machine tools, injection-moulding machines.

Head seal Prädifa series HS, Ultrathan®