Page 143 - Centrifugal Pumps Design and Application

Vertical Pumps 121

Figure 9-8. Barrel-mounted pump (courtesy BW/IP International, Inc. Pump Di-
vision, manufacturer of Byron Jackson/United™ Pumps).

pense. Often a special first-stage impeller with superior NPSH character-
istics is furnished. Otherwise, the bowl assembly is of a multi-stage de-
sign with identical impellers of the radial or semi-radial flow type. The
bowl assembly is either directly suspended from the discharge head or
connected to the head with a discharge spool, the length of which is de-
termined by the NPSH required.
The configuration shown in Figure 9-9 is of the pull-out type that per-
mits removal of the pump without disturbing either the discharge or suc-
tion nozzle connections. Pump alignment is, within reason, not affected
by any nozzle forces imposed. The suction nozzle can be located either in
the suction barrel or in the discharge head, in line with the discharge noz-
zle. The latter "in-line" construction is commonly used for booster appli-
cations in pipelines. The shaft sealing device in the discharge head is usu-