US Patent 7980562 Seal arrangement

Seal arrangements utilizing leaf seal elements are susceptible to excessive wear at their tips due to blow-down pressures. When the seal element is forced against a rear surface across the pressure differential between the sides A, B of an arrangement. These tips may be forced into engagement with the rotating shaft and therefore wear on the shaft as well as at the tip occurs. By providing channels which extend laterally across more than one seal element pressure relief is maintained and therefore a limit to blow-down force maintained. The channels also extend radially and normally on a low pressure side of the seal arrangement.