Page 401 - Centrifugal Pumps 2E

366 Centrifugal Pumps: Design and Application

Figure 17-6. Unbalanced seal heat generation (courtesy of John Crane).

From Figure 17-8 assuming that the stuffing box will be cooled to
70°F and that the temperature difference between the stuffing box and
pumpage is 100°F

The total heat input is used to estimate the required flow of coolant to
the seal. For single seal installations, the flow of coolant or seal flush
may be achieved through the use of a bypass line from pump discharge.
Some installations may require an injection from an external source of
liquid. A bypass line can be built internal to the pump or may be con-
structed externally on the unit. External piping will allow for the installa-