Polyurethane U-cup buffer seals
fig. 1) have a LUBRITHANE (TPU) sealing ring that incorporates a polyamide (PA) or polyacetal (POM) anti-extrusion ring. The flexible outside static sealing lip and notches in the front face ensure that pressure can return to the system side of the buffer and prevent build-up of pressure between the rod and buffer seals. These profiles are suitable for extreme pressure peaks and demanding workloads in heavy duty applications up to 690 bar (10 000 psi). They are available in metric (Size list [pdf]) and inch sizes (Size list [pdf]), some metric sizes fit seal housings in accordance with ISO 7425-2:1989.