When subjected to a pressure differential, the seal must resist the additional radial load generated by the pressure. If the seal is not designed to resist the pressure, it will be forced against the shaft, increasing the radial load, underlip temperature, friction and wear of the seal and the counterface, resulting in shortened service life.
Standard seals are rated for no more than 0,07 MPa at 5 m/s (10 psi at 1 000 ft/min), but SKF offers CRW5 and CRWA5 pressure profile seals that can accommodate 0,34 MPa at 5 m/s (50 psi at 1 000 ft/min). Beyond 0,34 MPa (50 psi), SKF offers a line of special order PTFE seals that can accommodate more than 3,5 MPa (500 psi).
In applications with pressure differentials, shaft seals should be secured axially from the low-pressure side to prevent them from moving axially. This can be accomplished by installing the seal into a counterbore (fig 1) or by using a retaining ring.