Centrifugal pumps use centrifugal action to increase the mechanical energy of a liquid. The key components of a centrifugal pump are the impeller, casing, shaft, and diffuser. The impeller rotates and imparts momentum and pressure increases to the fluid. The casing, or volute, features a gradually increasing space to reduce turbulence as fluid leaves the impeller. A double volute pump design separates the impeller section with a partition to reduce radial loads and vibration compared to a single volute pump. Properly priming a pump removes air from the suction line to prevent performance reductions.
5. Components of Pumps
Impeller: The rotating element of a pump which
consists of a disk with curved vanes. The impeller
imparts movement and pressure to the fluid
Impeller eye: That area of the centrifugal pump that
channels fluid into the vane area of the impeller. The
diameter of the eye will control how much fluid can
get into the pump at a given flow rate without causing
excessive pressure drop and cavitation.
Vane
3 or 5 or more than it. More vanes increases the
pump efficiency and reduce pressure pulsation.
6. Shaft
A rotating solid section. Sleeves in various area to
reduce damage to the shaft surface and cost of
maintenance. Pump shafts are usually protected from
erosion, corrosion, and wear at seal chambers, leakage
joints, internal bearing by renewable sleeves. The most
common shaft sleeve function is that of protecting the
shaft from wear at packing and mechanical seals.
Casing
Volute is casing. In it, the space between the impeller
and casing increases you go towards discharge. This
help reducing turbulence of fluid leaving impeller tips.
7.
8. Best Efficiency Point (B.E.P.): The point on a pump's
performance curve that corresponds to the highest
efficiency. At this point, the impeller is subjected to
minimum radial force promoting a smooth operation
with low vibration and noise.
Radial Force
Force that keeps the body in circular motion.
Cut Water. Narrow space between the impeller and
the casing in discharge area of the casing.
Radial Load. Force that is applied perpendicular to
the axis of a bearing ‘s shaft.
11. Double Volute Pump
Pump where the immediate volute of the impeller
is separated by a partition from the main body of
the casing. This design reduces the radial load on
the impeller making the pump run smoother and
vibration free.
Second cut water is located at 180˚ from first cut
water, this design results in much lower radial
load than are present in single volute pump.
12. Diffuser
Located in the discharge area of the pump, the diffuser
is a set of fixed vanes often an integral part of the
casing that reduces turbulence by promoting a more
gradual reduction in velocity
13. Advantage of Diffuser
•It balances the radial force thus reduction in
shaft deflection and it also eliminates the need of
heavy-duty radial bearing system.
•It reduces the turbulence by promoting gradual
reduction in velocity.
It has multiple cut water. Fixed vanes are there.
14. Pump Priming
Removal of air or non-condensable gases from pump
suction line is called pump priming
A pump with air in its casing is called Air Bound pump.
Air can be displaced by
•By drawing an incompressible liquid into the suction
line.
•Or by installing auxiliary priming tank connected to
the suction line
