DEFINITION TYPES maintenance

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Centrifugal Pumps
PresentedBy:
AMEER MUDASARIQBAL

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Pump
“Pump is a machine that imparts energy to the
liquid”.
Why Pumps are Required?
• To move liquid from one point to another at
same or higher elevation.
• To increase pressure of the liquid.

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Types of Pumps
Pumps can be divided into two
main categories:
Centrifugal Pumps
Positive Displacement Pumps.

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Centrifugal Pumps
A pump that works on the basis of
centrifugal force is called Centrifugal Pump.

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Types of Centrifugal Pump
 Single Stage Centrifugal Pump.
 Multi Stage Centrifugal Pump.
 Propeller Pump
 Turbine Pump.

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Single Stage Centrifugal Pump
Only one impeller on the shaft.
Used for low/medium pressure application.
Available in both horizontal & vertical
arrangements.
Mostly end suction with overhung impellers.
Impellers may be single suction or double suction.

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Multi-Stage Centrifugal Pump
Having two or more impellers on a shaft in series.
Used for higher discharge head.
Impellers are located at the centre of shaft.
Rotor is supported at shaft ends.
It has two stuffing boxes.

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Propeller Pump
A propeller whips & add energy to liquid instead
of impeller.
Liquid leaves the propeller in the same direction
as it enters.
Can handle large capacities.
Cannot increase much pressure.

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Turbine Pump
Mixture of impeller & propeller pumps.
Flow is half way through impeller & propeller
pumps.
Can be single or multistage.
Can handle high capacity & low head.

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Parts of Centrifugal Pump
The main parts of a centrifugal pump are:
 Impeller
 Casing
 Diffuser
 Stuffing Box

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Impeller
Most important part of centrifugal pump.
Mounted on shaft & rotates with it.
Comprises of eye, vanes and / or shrouds.
Increases velocity of liquid through vanes.

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Types of Impeller
1. Open Impeller
 Vanes are attached to the hub.
 No shroud to support vanes.
 Good for pumping stringy materials such as paper stock.
2. Semi Open Impeller
 Vanes are attached to the hub.
 Shroud on one side of the impellers.
 Good for viscous fluids.

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Types of Impellers
3. Closed Impeller
 Vanes are attached to the hub.
 Shrouds on either sides of the impeller.
 Pump efficiency is maintained by the use of close
clearance wear rings.
 Good only for reasonably clear liquids.

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Pump Casing
Enclosed space where the impeller rotates
with the shaft.
Converts velocity of liquid into pressure.
Has close clearance with the impeller.
Has two ends, Suction & Discharge.
Stuffing box is also provided in it.

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Types of Casing
1. Volute Casing
 Passage increases towards discharge nozzle.
 Pressure increases due to increase in area of the volute.
2. Concentric Casing.
 Passage remains concentric
 Discharge nozzle is always on vertical plane along the centre line
of pump.
 Diffuser is used to convert velocity into pressure.

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Diffuser
It is the stationery component in the pump casing.
It converts velocity head into pressure.
It also guides the liquid towards discharge nozzle.
In multistage pump, diffusers guides liquid to the
eye of next stage impeller.

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Stuffing Box
It is the space provided in casing for
installation of packing or mechanical seal to
prevent leakage along the shaft.

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Bearing
Definition
 Bearing refers to any kind of support, which is in direct
contact with a moving machine part.
 Bearings are designed to minimize friction, wear and
power losses. Every kind of machine uses bearing of
some kind.
Main types
1. Plain bearings
2. Anti-friction bearings

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Seals
Seals are used to form a barrier between two
spaces. Generally one of these spaces
contains process fluid at a pressure other
than atmosphere pressure.

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Packing
Packing is the simplest method of achieving process
fluid sealing in the stuffing box.
Packing can be described as a deformable material
used to prevent or control the passage of a fluid
between surfaces that move in relation to each other.
Packing can be manufactured from a wide variety of
different materials. It should be selected for a
particular service keeping in view the fluid to be
sealed and operating parameters (Temperature /
Pressure)

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Packing

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Packing with Lantern Ring

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Mechanical Seal
Mechanical seal is a device used to achieve
sealing of a rotating shaft of pumps,
compressors, mixing vessels at its entry to the
casing.
It has two flat radial surfaces, one rotates with
the shaft and the other is connected to the
casing & became a stationary part.

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Mechanical Seal Parts
Mechanical seal can be divided into two main Parts:
 Rotating Assembly: It comprises of
 Rotating face (Usually Carbon face)
 Seal ring packing (Secondary seal)
 Retainer or Cage
 Spring or Bellows
 Sleeve
 Stationary Assembly: It comprises of
 Hard face (Seat)
 Gland Plate

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Pusher Seals
Single Seal
 Internal Single Seal
 External Single Seal
Double Seal
 Back to Back Configuration
 Tandem Configuration

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Non-Pusher Or Bellow Seals
The seals use a flexible membrane which is in a
fixed position on the shaft and absorbs any
misalignment or movement by the flexibility of
bellows.
Two type of bellow seals are available.
 Elastomer Bellows : Uses an elastomer bellow or
diaphragm as the secondary sealing member.
 Very useful against excessive shaft end play & run out.
 Metal Bellows: Uses a flexible metal bellow instead
of elastomer.
 These seals are good for high temperature
applications.

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Non-Pusher or Bellow Seals

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Single Stage Centrifugal Pump

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Multi-Stage Centrifugal Pump

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Wear Rings & Balancing Holes

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Back Vanes

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Single Mechanical Seal

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Double Mechanical Seal
(Tandem Arrangement)

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Double Mechanical Seal