Handbook of Civil Engineering Calculations

FIGURE 8. Modern pump classes and types.

pump would probably be best. Table 5 also shows the typical characteristics of various
classes and types of pumps used in industrial process work.
Consider the liquid properties when choosing the class and type of pump, because ex-
ceptionally severe conditions may rule out one or another class of pump at the start. Thus,
screw- and gear-type rotary pumps are suitable for handling viscous, nonabrasive liquid,
Table 5. When an abrasive liquid must be handled, either another class of pump or anoth-
er type of rotary pump must be used.
Also consider all the operating factors related to the particular pump. These factors in-
clude the type of service (continuous or intermittent), operating-speed preferences, future
load expected and its effect on pump head and capacity, maintenance facilities available,
possibility of parallel or series hookup, and other conditions peculiar to a given job.
Once the class and type of pump is selected, consult a rating table (Table 6) or rating
chart, Fig. 9, to determine whether a suitable pump is available from the manufacturer
whose unit will be used. When the hydraulic requirements fall between two standard
pump models, it is usual practice to choose the next larger size of pump, unless there is
some reason why an exact head and capacity are required for the unit. When one manu-
facturer does not have the desired unit, refer to the engineering data of other manufactur-
ers. Also keep in mind that some pumps are custom-built for a given job when precise
head and capacity requirements must be met.
Other pump data included in manufacturer's engineering information include charac-
teristic curves for various diameter impellers in the same casing. Fig. 10, and variable-
speed head-capacity curves for an impeller of given diameter, Fig. 11. Note that the re-
quired power input is given in Figs. 9 and 10 and may also be given in Fig. 11. Use of
Table 6 is explained in the table.
Performance of data for rotary pumps are given in several forms. Figure 12 shows a
typical plot of the head and capacity ranges of different types of rotary pumps. Recipro-
cating-pump capacity data are often tabulated, as in Table 7.

Class Type

Single- stage

Multistage

Simplex

Duplex

Triplex

Quadruplex

Quintuple*

etc.

Centrifugal

Rotary

Reciprocating

Volute

Oiffuser

Regenerative-turbine

Vertical - turbine

Mixed-flow

Axial- flow (propeller)

Gear

Vane

Cam - and - piston

Screw

Lobe

Shuttle-block

Direct-acting

Power (including

crank- and - flywheel)

Diaphragm

Rotary - piston