axial pump senatorlibya

ROTODYNAMIC PUMPS

Rotodynamic Pumps

Mixed flow

Axial flow

Centrifugal

Rotodynamic

Turbine

PUMP

Positive displacement

Diaphragm

Piston

Plunger

Reciprocating Rotary

Gear

Lobe

Sliding Vane

Screw

:Axial and Mixed flow

Axial and Mixed Flow Pumps are the normal choice for high-volume, low-pressure pumping duties and

particularly for large-scale primary water supplies, flood control, irrigation and drainage. Such types are available in

a wide range of sizes and capacities.

It is a general characteristic of such pumps that the power input curve is much flatter than that of a centrifugal

pump, thus input power demand does not vary very much with the working point. Hydraulic performance, however,

differs appreciably.

Rotodynamic Pumps


Axial flow pumps generate head pressure through an axial motion developed by a combination of propeller and

internal vane design. The combination induces fluids to travel strictly along the axial of the pump drive shaft.

The mixed flow pump employs a chamber /impeller /vane design to impart both an axial and radial motion to fluids

traveling downstream.

Rotodynamic Pumps

This powerful motion is created by lifting the fluids with an impeller, while simultaneously forcing fluids out against the

bowl like impeller chamber.


The outward movement known as an upper diffuser section. By combining axial and centrifugal motion, the

mixed flow pump generates greater head pressure to downstream fluids than is possible with a single motion

axial pump.

These differences are noted in the generated comparative H-Q curve.

Rotodynamic Pumps


Rotodynamic Pumps

Q

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Rotodynamic Pumps

In the case of a mixed flow pump, the H-Q curve tends to be steep,

with the point of maximum efficiency displaced towards maximum

capacity.


Rotodynamic Pumps

The H-Q curve of an axial flow pump has substantial falling characteristics although the actual head obtainable

is much lower.

Efficiency is higher over a greater (percentage) range of head than for

a centrifugal pump.


Rotodynamic Pumps

:General form

Driver Head shaft

Seal

Pump shaft

Impeller

Discharge elbow

Column assembly

Bowls

Suction bell

Axial and mixed flow pumps are commonly mounted vertically,

directly over a sump. This is most often the case when the source of

water is a river or reservoir.

Fluids enter through a flared suction bell that has been reinforced by

heavy vanes.


Rotodynamic Pumps

:General form

Driver Head shaft

Seal

Pump shaft

Impeller

Discharge elbow

Column assembly

Bowls

Suction bell

The vanes, in addition to lending support to the suction bell, act to

direct the liquid flow parallel to the drive shaft as it travels upstream.

Once past the suction bell, fluids encounter either an axial propeller or

a mixed flow impeller.


Rotodynamic Pumps

:General form

Driver Head shaft

Seal

Pump shaft

Impeller

Discharge elbow

Column assembly

Bowls

Suction bell

While differing in design, both are always dynamically balanced, one-

piece castings, mounted on a stainless steel pump shaft.


Rotodynamic Pumps

Driver:

Driver Head shaft

Seal

Pump shaft

Impeller

Discharge elbow

Column assembly

Bowls

Suction bell

The drive shaft may be encased in a tube or open, with supports properly

spaced for intermediate shaft bearings. Positive drive is provided

by a heavy-duty drive key and thrust collar.

A variety of drivers may be used, however, electric motors and right

angle gears are most common.


Rotodynamic Pumps

Driver:

Driver Head shaft

Seal

Pump shaft

Impeller

Discharge elbow

Column assembly

Bowls

Suction bell

These types of drivers can be grouped into two categories:

1. Hollow shaft drivers - the pump shaft extends through a tube in the

center of the rotor and is connected to the driver by a clutch assembly at

the top of the driver.


Rotodynamic Pumps

Driver:

Driver Head shaft

Seal

Pump shaft

Impeller

Discharge elbow

Column assembly

Bowls

Suction bell

These types of drivers can be grouped into two categories:

2. Solid shaft drivers - the rotor shaft is solid and projects below the

driver-mounting base. This type driver requires an adjustable

coupling between the pump and driver.


Rotodynamic Pumps

Column assembly:

Driver Head shaft

Seal

Pump shaft

Impeller

Discharge elbow

Column assembly

Bowls

Suction bell

The column assembly is of two basic types, either of which may be used

on close coupled units:


Rotodynamic Pumps

Column assembly:



1. Open line shaft construction utilizes the liquid being pumped to

lubricate the line shaft bearings.


Rotodynamic Pumps

Column assembly:



2. Enclosed line shaft construction has an enclosing pipe around the

line shaft and utilizes oil, grease or injected liquid to lubricate the line

shaft bearings.


Rotodynamic Pumps

Column assembly:

The column assembly will consist of column pipe, which connects the bowl assembly to the discharge

head and carries the pumped liquid to the discharge head, the shaft,

which connects the bowl assembly to the discharge head, the head

shaft, which connects the line shaft to the driver.


Rotodynamic Pumps

Column assembly:

Column pipe may be either threaded or flanged and may contain bearings

if required for the particular unit.

Note: Some units will not require a column assembly, having the bowl assembly connected directly to the

discharge head.

:Note


Rotodynamic Pumps

Discharge head assembly:




Rotodynamic Pumps

The discharge head supports the driver and bowl assembly as well as

supplying a discharge connection (the underground discharge

connection will be located on one of the column pipe sections below the

motor stand).



Rotodynamic Pumps

A shaft sealing arrangement is located in the discharge head to seal

the shaft where it leaves the liquid chamber. The shaft seal will usually

be either a packing box or mechanical seal assembly.



Rotodynamic Pumps

Bowl assemblies:

The bowl assembly consists of impellers rigidly mounted on the

bowl shaft, which rotate and impart energy to the fluid.

The bowls (or diffusers) contain the fluid at increased pressure and direct

it vertically to the next stage and eventually to the column pipe.


Rotodynamic Pumps

Bowl assemblies:

The suction bell or case directs the fluid into the first stage impeller.

Bearings are located in the suction bell, discharge case, and between

each impeller.

Impeller


Rotodynamic Pumps

Bowl assemblies:

The rotating element is mounted in an individual housing, which is

usually replaceable and situated just above the section bell, close to the

pump inlet.

The housing may be bronze, stainless steel or any other material

similar to the impeller.? Why

Impeller


Rotodynamic Pumps

Bowl assemblies:

The same resistance to shock.

The same thermal extension.? WhyTo keep a clearance between

impeller and casing as designed (performance of the

pump).

Impeller


Rotodynamic Pumps

Bowl assemblies:

After emerging from the housing, fluids travel past an upper diffuser

chamber and out through the guide case.

The guide case, consisting of a column pipe and discharge elbow is

of welded steel plate or cast iron.


Rotodynamic Pumps

Bowl assemblies:

Sections are flanged or bolted together.

A registered fit is used to maintain proper alignment on all mated parts.


Rotodynamic Pumps

Pullout options, which make for easier maintenance and inspection,

are a common feature of these pumps, the best designs permit

removal of the entire bowl assembly (including all rotating parts, diffuser,

impeller housing and suction bell) through the outer shell, without

disturbing either the discharge or floor plate connections.

Pullout options:

Channel impeller pumps:

Rotodynamic Pumps

A channel impeller pump employs an impeller with turbine-type blades mounted on the periphery running in

an annular channel (or channels) surrounding the periphery of the wheel.

In practice, only two main subtypes emerge, known generally as the peripheral pump and side channel pump

respectively.

Rotodynamic Pumps

The main difference is in the form and positioning of the channels:


The peripheral pump has a double-sided channel in which the liquid circulates, this channel being located partly in

the cylindrical part of the casing and partly in the side plates.

The side-channel pump has two channels cut in the side plates only, adjacent to each side of the impeller blades.

Rotodynamic Pumps

Characteristics are quite different, eg the side-channel pump is self-priming and can develop a much higher

head, although its efficiency is lower. Hence, the two are distinct types.


The peripheral pump is also known as a regenerative pump.

Rotodynamic Pumps

H-QEfficiency

BHP

HEAD,BHP & Efficiency

100%

Peripheral

Capacity


Rotodynamic Pumps

H-Q

Efficiency

BHP HEAD,BHP & Efficiency

100%

Side-channel

Capacity


Rotodynamic Pumps

H-Q

Efficiency

BHP HEAD,BHP & Efficiency

100%

Side-channel

Capacity

H-QEfficiency

BHP

HEAD,BHP & Efficiency

100%

Peripheral

Capacity


Rotodynamic Pumps

Centrifugal

Regenerative

Axial flow

Axial flow

Capacity

HEAD

Regenerative pumps have a substantially straight and

sleep H-Q curve.

Pressure developed tends to rise sharply with decreasing

capacity making this type unsuitable for discharge

regulation by throttling. Power output falls with increasing

capacity.


Rotodynamic Pumps

Mixed flow

Axial flow

Centrifugal

Rotodynamic

Turbine

PUMP

Positive displacement

Diaphragm

Piston

Plunger

Reciprocating Rotary

Gear

Lobe

Sliding Vane

Screw

Turbine pumps (Regenerative:(

Rotodynamic Pumps

Turbine pumps obtain their name from the many vanes

machined into the periphery of the rotating impeller. Heads

over 900 feet are readily developed in a two-stage

pump.


Rotodynamic Pumps

The impeller, which has very tight axial clearance and uses pump channel rings, displays minimal recirculation losses. The channel rings provide a circular channel around the

blades of the impeller from the inlet to the outlet.


Rotodynamic Pumps

Liquid entering the channel from the inlet is picked up

immediately by the vanes on both sides of the impeller and pumped through the channel

by the shearing action. The process is repeated over and

over with each pass imparting more energy until the liquid is

discharged .

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