Pumps
DOE-HDBK-1018/1-93
CENTRIFUGAL PUMPS
Diffuser
Figure 3 Centrifugal Pump Diffuser
Some centrifugal pumps contain
diffusers. A diffuser is a set of
stationary vanes that surround the
impeller.
The purpose of the
diffuser
is
to
increase
the
efficiency of the centrifugal pump
by allowing a more gradual
expansion and less turbulent area
for the liquid to reduce in velocity.
The diffuser vanes are designed in
a manner that the liquid exiting the
impeller will encounter an ever-
increasing flow area as it passes
through the diffuser. This increase
in flow area causes a reduction in
flow velocity, converting kinetic
energy into flow pressure.
Impeller Classification
Impellers of pumps are classified
Figure 4 Single-Suction and Double-Suction Impellers
based on the number of points that
the liquid can enter the impeller
and also on the amount of
webbing between the impeller
blades.
Impellers can be either single-
suction or double-suction.
A
single-suction
impeller
allows
liquid to enter the center of the
blades from only one direction. A
double-suction impeller allows
liquid to enter the center of the
impeller blades from both sides
simultaneously. Figure 4 shows
simplified diagrams of single and
double-suction impellers.
Rev. 0
ME-03
Page 3
