TM 5-813-9
CHAPTER 3
PUMPING EQUIPMENT
3-1. Pumps.
are selected. Lubrication for horizontal pumps will
be oil bath or grease. Vertical dry pit pumps will be
a. General. The location of the pump station
grease lubricated. Vertical wet pit pumps will have
and intake structure, and the anticipated heads and
oil or water lubrication.
capacities are the major factors in the selection of
c. Pump applications.
pumps. The function of a pump station in the
(1) Booster pumps. Booster pump may be
overall distribution system operation can also affect
above-ground or underground. Figure 3-1
the determination of capacities. Basic pump
illustrates schematic piping of two types. Pump and
hydraulic terms and formulas, pump fundamentals
controls selection for in-line booster pumps will
and applications, and instructions for installation,
consider minimum suction pressure, and automatic
operation and maintenance are given in the Hy-
draulic Institute Engineering Data Book and Hy-
discharge cut-off pressure. For small booster pump
draulic Institute Standards. It is recommended that
applications, as for remote housing or satellite
these books be part of the permanent library of the
military facilities with peak water demands of less
fluid system designer.
than approximately 1500 gpm the designer should
b. Pump types. There are generally two types of
consider a pre-assembled skid mounted package
pumps used for potable water pumping applica-
unit including all of its hydrostatic, flow, instrument
tions-the vertical turbine pump, line shaft and
and electrical components.
submersible types, and the centrifugal horizontal or
(2) High lift pumps. Figure 3-2 shows examples
vertical split case pump designed for water-works
of pumps supplying the distribution system.
service. If the pump station and intake structure are
d. Pump curves. With the system head curve
to be located within a surface or underground
defined, it is possible to select a pump to deliver the
reservoir, vertical turbine pumps with the column
required capacity. Manufacturer's published pump
extending down into the reservoir or its suction
head-capacity curves for the selected type of pump
well will be a logical choice. If the pump station is
will be used for this purpose. Since these pump
located at an above ground storage facility, split
curves usually apply to a particular impeller and
case centrifugal pumps will be the preferred
pump design, different manufacturers may show
selection. These pumps are normally horizontal but
slightly different performance for the same type and
vertical split case pumps are common where there
size of pump. Therefore, several manufacturers'
is limited space. Flexible couplings will connect
pump curves should be checked to establish a
pump and driver shafts. Split case pump design is
realistic and cost effective criteria for the pump
used for ease of maintenance of the rotating
selection. Figure 3-3 shows three types of pump
elements, which can be removed without
head capacity (performance) curves; a "normal
disconnecting the suction or discharge piping.
rising" curve, a "drooping" curve and a "steeply
For standard waterworks design for potable sys-
rising" curve.
tems, pump casing will be cast iron and impellers
will be bronze. Base for pump and driver will be
For pumps in a typical water supply and distribution
cast iron or fabricated steel. Pump impeller and
system, only pumps with "normal rising" to "steeply
casing may have wearing rings depending upon
rising" performance curves should be used. Pumps
manufacturers' recommendations and consideration
with these characteristics will perform well in
of the cost of replacing the rings. Pumps will have
parallel operation and will have relatively small
mechanical seals or packing seals, ball or roller
capacity change with pressure changes. In addition,
bearings, and lubrication system. Pumps which may
the brake-horse power curve will be relatively flat,
operate under extreme conditions such as at the
which will minimize the risk of overloading the
ends of pump curves or under frequent on-off
motor particularly in applications in direct pressure
operation will have packing seals in lieu of
systems with possible high pressure fluctuations.
mechanical seals. Mechanical seals will be consid-
ered for pumps likely to stand idle for long periods
3-2. Pump Drives. Pump drives for water supply
of time. Where scale or abrasive water conditions
and distribution pumps will be electric motors.
exist, pump linings and other material options for
Diesel or other fuels will be considered as a power
impeller, shaft, wear rings, and seals are available.
source only for emergency use. The drivers will be
A water analysis at the point of service must be
constant speed AC motors of the squirrel-cage-
secured and analyzed before non-standard materials
3-1
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