Buffer seals incorporating slide rings
RSB profiles (fig. 2) have a nitrile rubber (NBR) energizer and a PTFE slide ring.
The energizer is designed to hold the slide ring in the proper and permanent sealing position against the rod seal side of the housing. Conventional buffer seal designs can shift axially within the groove and push fluid into the rod seal groove when subjected to abrupt pressure peaks. This ultimately causes rod seal failure. However, the patented design of RSB profiles prevents any axial shifting of the slide ring. Therefore, these profiles protect the rod seal in applications where conventional buffers are not sufficient. In combination with grooves in the energizer outside diameter and notches in the front face of the slide ring (fig. 3), the protrusions also ensure that pressure can return to the system side.
RSB profiles are suitable for pressures up to 400 bar (5 800 psi) in medium to heavy duty applications and are available in inch sizes (→ Size list [pdf]). For additional information, refer to RSB profile data.
On request, for the most demanding applications of large equipment, SKF can manufacture these profiles with polyamide (PA) slide rings for additional extrusion and wear resistance.