Page 424 - Centrifugal Pumps 2E

388 Centrifugal Pumps: Design and Application

failed, it was replaced by another seal. Fitting a seal to packing cross
sections was sometimes difficult, particularly when multiple seal ar
rangements were required. In addition, the smaller the space around the
seal, the warmer it would run.
Figure 17-25 shows the original stuffing box and the new revised box
that allows more than two times the clearance over the pump shaft. The
new box dimensions allow a current ANSI seal to run 25 °F cooler than
the original design. By opening up the back of the stuffing box and pro-
viding a slight taper to the bore, the stuffing box will run approximately
40°F cooler than the original design. This data was developed testing
conventional seals that are considered standard in the original stuffing
box. These include elastomeric bellows, wedge, and O-ring seals. Stuff-
ing box design plays an important part in providing a good environment
for the mechanical seal.

Figure 17-25. Basic stuffing box designs.