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NAME 429: Marine Engineering

Credit : 3.00, 3 hrs./wk.

No. of class test: 4

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Course contentsPumps:

Characteristics

NPSH

Head Calculation

Blowers and compressors

Refrigeration and air-conditioning

Thermodynamics

Principles

Air-conditioning system for ships

Heating and ventilating system

Air treatment in cargo spaces

Marine auxiliary machineries:

Windlass, winches, cargo access equipment for dry, unitized, liquid and

cryogenic cargoes

Steering gear: types and characteristicsDrive design criteria, testing , commissioning

Pipe materials, piping systems and valves

steam traps,

Anchors, anchor hawse, chains etc.

Emergency systems

Propeller, shaft and stern gear arrangement 2

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A process of addition of kinetic and potential energy to a liquid for the purpose of

moving it from one point to another. This energy will cause the liquid to do work

such as flow through a pipe or rise to a higher level and Pump gives pressure to

fluid passing through it and discharges the fluid to the outside.

Pump: Introduction

Take fluid where it is needed with the desired pressures and flows;

Take away fluid from areas where it is not needed;

Control: control flow volume; pressure and timing.

A pump is a machine used to move liquid through a piping system

and to raise the pressure of the liquid.

Pumps are used to transfer liquids

from low-pressure zones to high-

pressure zones

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Pumps are classified on the basis of :-

The applications they serve,

The materials from which they are constructed,

The liquids they handle, and even their orientation in space.

All pumps may be divided into two major categories:

(1) Dynamic

(2) Displacement

Classification Of Pump :

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Dynamic Pumps:

Inside the machine: Energy is continuously added to increase

the fluid velocities inside the machine (i.e., increase the kinetic

energy of the fluid);

Between the Machine and the Discharge: A diverging type of

geometry (e.g., volute, or diffuser) is used to convert velocities

(kinetic energy) into pressure.

Displacement Pumps:

Energy is periodically added by application of a force to one or

more movable boundaries; resulting in a direct increase of

pressure.

Pump: classification

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Pump: classification

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Pump: classification (contd.)

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Centrifugal pump: basic principle

Consists of two basic parts:

1. The rotary element or impeller

2. the stationary element or casing (volute)

X-section of a centrifugal pump

Pump is filled with liquid and the impeller is rotated

Rotation imparts energy to the liquid causing it to exit the impellers' vanes at a greater

velocity than it possessed when it enteredThis outward flow reduces the pressure at the impeller eye, allowing more liquid to

enter

The liquid that exits the impeller is collected in the casing (volute) where its velocity is

converted to pressure before it leaves the pumps discharge

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Working Principle of Dynamic Pumps

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Pump head

The net work performed on the liquid by the pump.

Composed of 4 parts:

1. Static head or elevation, Hs

2. Pressure head or pressures to overcome, Hp

3. Friction head, Hf

4. Velocity head, Hv

H = P/D

Where, H=head, P=pressure, psi, D=density

Head (ft.)= (2.31 X Pressure, psi)/Sp. Gr.

Pressure, psi= pressure in pounds per square inch2.31= conversion factor

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Pressures inside the pump

Suction pressure

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