The Parker Prädifa RS rotary sealing set consists of a high-strength thermoplastic slide ring with particularly stable thermal properties and an elastomer preloading element. The special contact surface geometry at the inner diameter of the slide ring with the patented (EP 0 643 243 B2) alternating pitch has a major beneficial effect on the lubrication of the seal. This has a positive impact on both friction and wear. The preloading element responsible for the static sealing function has a rectangular cross-section. Compared to O-rings, this has advantages with regard to contact load (sealing) and deformation behavior (pumping inside the groove). The dynamic interior sealing method is preferable. We do not recommend a dynamic exterior sealing arrangement. The slide ring compound used and its geometry allows the use of the seal even under maximum permissible pressure (and in case of pressure peaks) without requiring additional anti-extrusion rings. At the same time, it is possible to take maximum advantage of the diameter play between rotor and stator without any functional impairment. In principle, the seal can also be used as an exterior end seal. In case of doubt, however, we recommend our C5 or C9 product series.
- Enhanced sealing performance in non-pressurized conditions.
- Robust seal profile for harshest operating conditions.
- Extreme wear resistance.
- Long service life thanks to application-optimized compounds.
- Insensitive to pressure peaks.
- Improved lubrication due to pressure medium deposits in the dynamic contact area.
- Extremely high extrusion resistance.
- Installation in closed and undercut housings.
Range of application
Primarily for alternating sealing of rotary applications in rotating tracks, pivot drives, hose reels, and in machine tool hydraulics.
Operating pressure ≤ 500 bar
Operating temperature -35 °C to +100 °C
Sliding speed ≤ 0.5 m/s
Recommendation for rotary transmissions:
P × v ≤ 40 for L = 4.1 to 4.2 P × v ≤ 70 for L = 6.0 to 6.3
(For definition see catalogue „Hydraulic Seals“, chapter „Rotary Seals“, introduc- tion.)
The standard compound for the slide ring is a thermoplastic compound (W5071) with outstanding physical properties.
The expander ring consists of our tried and proven standard NBR compound N3571 with 70 Shore A. For higher temperatures, we recommend HNBR compounds.
The axial fit of the Parker Praedifa seal is especially narrow and suitable for grooves conforming to DIN ISO 7425. This benefits the total installation length of the rotary transmissions. By selecting suitable compounds, snap installation depending on profile width down to rotor diameter of the app. 30 mm is possible. Below that, we recommend axially open grooves for installation.