Page 427 - Centrifugal Pumps 2E

Mechanical Seals 391

seal to work in an environment where the liquid in the seal chamber is
near its vapor pressure. As a rule of thumb, when the stuffing box pres-
sure is less than one-third of the vapor pressure, a seal face design with
hydropads should be considered. Hydropads or lubrication recesses are

Figure 17-28A. Piping plans for mechanical seals from A.P.l. Standard 610,6th
Edition. (Reproduced courtesy American Petroleum Institute.)