Page 145 - Centrifugal Pumps Design and Application

Vertical Pumps 123

• Loading pumps in underground caverns used for storing petroleum
products. The pump is mounted in a caisson.
• Dewatering pumps in mines. The pump is mounted in a mine shaft,

Water Well Pumps

This is the most common application and covers a broad range of ser-
vices such as municipal water supply, irrigation service, and industrial
service water. For settings down to 400 feet, a line shaft construction
with a surface mounted driver is normally used. It should be noted that
line shaft construction requires that the well be straight, so that the col-
umn shaft bearings can be kept in alignment. The well must be checked
for mis purpose prior to pump installation. For settings beyond 400 feet,
and where electric power is available, the close-coupled submersible unit
is usually the most cost-effective and also the most reliable. The close-
coupled design often permits running at higher rotative speeds. With
elimination of line shafting and corresponding bearings, well straightness
is not as important. However, the well should be "caged" (checked with
a dummy pump/motor assembly) prior to pump installation to make sure
the unit will not bind in "dog legs."

Inctfrte-Mounted Pumps

The cost of excavating and providing an adequate intake and mounting
structure for vertical pumps on lakes and river banks can be substantial,
particularly where large fluctuations in water level require high struc-
tures. A less costly installation may be achieved by mounting vertical
pumps on an incline on a lake or river bank, as shown in Figure 9-10.
The pump is mounted inside a pipe or in a trough, permanently anchored
on piers along the bank with the bowl assembly at a sufficient depth to
provide adequate submergence. The pump can either be of the line shaft
type with an electric motor drive or close coupled to a submersible motor,
in which case both the pump and motor are mounted in the pipe or on the
trough,

Cavern Pumps

For ecological as well as safety and economic reasons, petroleum prod-
ucts, ranging from propane to crude oil, are often stored in natural or man-
made caverns rather than in large surface tanks [7]. ^fell type pumps, most
commonly driven by submersible motors, are used for unloading the cavern
before the product is further transported by pipeline or ship. The pumps are
usually mounted in a caisson, which is sealed at the top ami terminates near