Page 139 - Centrifugal Pumps Design and Application
P. 139
Vertical Pumps 117
Figure 9-4. Submersible well pump (courtesy BW/IP international, Inc. Pump
1
Division, manufacturer of Byron Jackson/United " Pumps).
sure, plus the static liquid level above the first-stage impeller, less cor-
rection for the liquid vapor pressure at the pumping temperature.
Because the cost of a pit or intake structure is high and dependent on
the depth of the structure, the submergence is typically kept to a mini-
mum in line with sound design practices. As a result, the maximum pump
speed is limited by the NPSH available and the required flow rate. Sin-
gle-stage pumps can usually be furnished for pumping heads up to 200
feet, but multi-stage pumps are required for higher heads. The bowl di-
ameters of well pumps and their corresponding flow rates are restricted.
However, wet pit pumps can be furnished in any size and therefore for
