maintenance pump

7/25/2019 maintenance pump

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PUMPS


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Defnition

-

A device whichadds energy to auid, causing anincrease in its

pressure andperhaps amovement o the

uid

Pump


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rinciple Functions of pump

produce velocity overcome the fricti

on and fitting losses (shock losses)

overcome external

pressure


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umping System

-Consists of a pump

-The suction branch

d aws flu id f om a sou ce

-The discharge branch

t anspo ts flu id to the dest inat i

on


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Types of umps

isplacement pumps

! "eciprocating pumps

! "otary pumps "otordynamic pumps

! Centrifugal pump

! Propeller pump #et pumps

Axial Flow pump


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isplacement umps

The liquid or gas is displacedfrom the suctionside to the discharge side of the pump by themechanical variation of the volumeof a chamber

or chambers.

They can be further subdivided into two classes :

1. eciprocating Piston or Plunger Pumps!. otary Pumps


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isplacement umps


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"eciprocating umps

Pumping done by plungeror pistonina li$uid cylinder

Suitable and better efficiency for handling small volumesand high differentialpressure

Suitable for any re$uired viscosity Self priming (self evacuating air from p

ump and suction line)

% & ' rea n


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iston ump

The liquid or gas is displacedin and thenfrom the cylinder by the moving of piston

in a cylinder "mechanical variationof the volume#

$pplicationsMost suitable and e%cient for handlingsmall volumes and high di&erential pressure

Suitable to handle any required viscosity


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iston ump


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"eciprocating umps

oes not discharge a steady flow* instead in a series of pulsations

Therefore cause vibration and hammering at high speeds resulting in shockto pump and fittings

+sually fitted with air vessel to reduceeffects of unsteady flow of discharge


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"otary umps

Pumping done by forcinga li$uid through the pum

p cylinder or casing by means of screws or gear Suitable forintermediate

range of volume* interme

diate differential pressureandlow or intermediate viscosity

Self priming

'ess efficient


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"otary umps

Steady flow but less efficient than reciprocating pumps because of large are

as and running clearance ,ear increases the clearances nd results in loss in efficiency* espec

ially when handling low viscosity fluids


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Screw ump


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Screw ump

Screw pumps are rotary positive displacement pumps.

'low of liquid is a(ial

)iquid is carried between the screw threads ofrotors and displaced as the screws rotate.

Screw pumps themselves do not create pressure*they simply transfer a quantity of +uid from the inlet to

the outlet.

Pressure is built up on the outlet as a result of resistance+ow in the discharge line.


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-ertical Screw ump


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.ear ump


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.ear ump

,ften called e(ternal gear pumps

Suitable for handling all clean liquids

particularly e&ective where the +uid has lubricatingproperties. They are often used as attached lubricating oil pumps inau(iliary engines and as transfer pumps in lubricatingand fuel oil systems.

Should not be run dry or else they will overheat andsei-e up

y/pass valve arrangement is required


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.ear ump


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-ertical .ear ump


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-ane ump


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-ane ump

Sliding vane pumps are light Simple in construction 0ompact

)ow/cost

They are particularly suitable for low and mediumpressure duties

0an handle both gases and liquids

,ften used as attached circulating water pumps ofau(iliary engines

0an also be used for air handling as rotary compressorsor e(hausters


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'obe ump


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'obe ump

,ften called internal gear pumps

More gentle than e(ternal gear pump

The generation of high localised pressures is avoided

Shear forces generated are substantially lower

Suitable for handling higher viscosity and shear/sensitive

+uids

$lthough it is equally suitable for handling low viscosityand even volatile liquids with suitable shaft seals

The normal range of pressure rising to !1 g2cm!

andcapacities up to 344 tonnes2hr


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'obe ump

5ave two types nown as the Three/'our and Seven/6ight

The Three/'our are particularly suitable for handlinghigh/viscosity +uids such as heavy fuel oil and can runcomparatively slow speeds

The Seven/6ight types are designed to operate at higherspeeds of around 7!4 rev2min and are e%cient in handlin

lower viscosity +uids.


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'obe ump

8oring procedures


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'obe ump

Two types

Three/'ourSeven/6ight


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ump Curve


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ischarge Calculation

$ single acting reciprocating pump has a bore of 944 mmdiameterand piston stroe of !44 mm. f the cranshaft speed of the pump i94 rpm; it delivers nd the theoreticaldischarge; coe%cient of discharge and percentage of slip.

Solution:?iameter @ 944 mm Stroe @ !44 mm n @ 94 rpmAactual @


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"otordynamic ump

Ability to handle large volume ow rates at regular delivery Ability to handle low to medium heads

Ability to handle liquids rom medium to lowviscosities

Ability to handle contaminated liquids Quiet in operations

ow care and maintenance requirements !omparatively lower cost" #o ability to sustain pressure when at rest" $he inductive action relies entirely on the impeller

motion


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"otordynamic ump


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Centrifugal ump


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Centrifugal ump


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Centrifugal ump


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Principle functions of0entrifugal Pump

%ery simple design&oving part is only an

impeller attached to a shat

driven by a motor$wo main parts' impellerand di(user

A di(user or volutehouses the impeller and

captures the water o( theimpeller


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Centrifugal ump


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,orking rinciple of Centrifugal ump

)$he impeller with fxed blades *vanes+ is mounted ona rotating shat in a fxed casing"

)hen the impeller rotates, a high velocityis impartedto the liquid due to the centriugal orce"

)As the liquid ows radially outwards into the volute)shapedpump casing or a di(user, its high velocity is converted intostatic pressure")$he vacuumcreated at the pump inletenables theatmospheric pressure to orce more liquid into the inlet

opening")$his process will continueas long as rotating motion isprovided to the rotor and the supply o liquidis available"


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/ow pressure is produced

in centrifugal pumpsFrom the -ernoullis equation, the total head o a liquid particle inmotion is the sum o its potential head, .inetic head and pressureheady"

v2 p

H /

Z 0 )))))) 0 ))))) 2g 1g

2n a centriugal pump, the sectionarea o a volute casing and

di(user is gradually increased"

!onsidering two sections 3 and 4"$he area o section3 is smaller,the area o section4 is bigger"


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/ow pressure is produced

in centrifugal pumps$he -erloullis equation at section 3 and 4 is'

%34 53 %4

4 54630 )))))) 0 )))))) / 640 )))))) 0 ))))

4g 1g 4g 1g

63is equal to 64" From the continuity equation, a3%3/ a4%4

*a is the area o the section, % is the velocity at the section+"hen a4increases, then %4decreases" hen %4decreases

then 54increases"

$hereore the pressure is produced in centriugal pumps byconverting .inetic head to pressure head"


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9? view of a centrifugalpump


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-ertically 0ounted umps

$dvantages

6liminate the overhanging load on

wear rings ,ccupy lesser space )ess ha-ardous . less open +oors . easier mobility for engine room crew 6lectric motors are higher; less prone to

+ooding damage Simple support pump foundation )ower cost


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-ertical Centrifugal ump


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-ertical Centrifugal ump

ear 7ing


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0ulti!stage ump

iming to get higher pressure


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ropeller ump

)arge Eolume rate and low pressure provided

8xample 9se' &ain sea water cooling in steam condenser o turbine engin


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Centrifugal Pump Components

Centrifugal Pump can be split into two main assemblies.

Mechanical Assembly Hydraulic Assembly


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0entrifugal Pump $ssembly

&echanical Assembly

:hat seal:hat

-earings;ousing

Drive couple

;ydraulic Assembly

2mpeller:uction 2nlet

%olute

:eal 7ing


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5ydraulic $ssembly 'unctions

mpeller

2t is a rotating component whichtransers energy rom the motor that

drives the pump to the uid being

pumped by orcing the uid outwardsrom the centre o rotation" 2mpellersare round discs with fns to push the

uid"

Suction nlet2t is the inlet where the water to be

pumped enters

Eolute 2t is the outlet where the water exit

Seal ing2t prevents the medium rom lea.ing

to the atmosphere

0omponents in a0entrifugal Pump


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Centrifugal ump arts

Eolute0asing

mpeller Suction 0over


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0omponents in a0entrifugal Pump

Mechanical $ssembly 'unctions

Shaft seal2t is to prevent the medium *liquid+ rom

lea.ing into the atmosphere"

Shaft2t is connected to the impeller to provide

the centriugal orce"

earings2t is used to provide the shat a rictionless

movement"

5ousing 2t holds the di(erent parts together in thepump"

?rive couple2t connects the motor shat and the

impeller shat" $he motor provides theimpeller with .inetic orce

Materials


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MaterialsUsed

Component Materials used Materials properties

Pump Casing Cast iron It is low impact resistance, low ductility, good forcasting, easily machinable, good strength, hard.

Impeller Bronze It is less brittle than iron and has a lower casting temperature,low-friction properties, resistance to corrosion by sea water

Shaft Stainless steels It hasa higher resistance to oidation !rust" and corrosion in

many natural and man made en#ironments.

Bearing Carbon steels Fatigue resistance and ductile core provides toughness.


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1alance xial Force


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1alance xial Force


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1alance xial Force

Mae a balance hole to balance a(ial force

'unction of wear ring: to prevent internal leaage


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erformance Curves (/!%)

0entrifugal pumps are generally operated at constant speed andregardless of load

The characteristic curves of the head2volume delivery rate for a

given design speed can be drawn.

The theoretical H/Qcurve is a straight lineof negative slope.

The real operating characteristics lies below this line to the e(tentof losses within the pump. These losses are :

a# shoc and eddy losses due to the +ow into and out of the impellb# losses due to +uid friction and turbulence.

The losses should be minimum at the design operating point.


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;)Q !urve

5rovided by

&anuacturer


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2fficiency of ump

6%ciency is the ratio of +uid output power to input power

'luid power6%ciency @ /////////////////

nput power

'luid power can be calculated as the product of g A 5.

The e%ciency curve is conve(

The ma(imum e%ciency occurs at a point somewhat betweenma(imum and minimum discharge head and throughputconditions.


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erformance Calculation

t is used to transfer water from one tan to another; in whichthe water level is D.4 m higher; through 144 m of 1=4 mm diametepipe with friction factor f @ 4.4!4and >ttings with total value of14.4.

?etermine the pump discharge and the power input.

?ischarge

"l2s#

4


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Solution:Step 1:To draw the 5/A curve according the data given and the

e%ciency curve according to the data given.Step !: To calculate system head at each discharge point by using

5system@ 5s F 5mF 5f8here: 5system // System 5ead "Unit: m#

5s // Static 5ead "m#; here is Dm

5m // Minor )osses "m#

5f // 'riction )osses "m#

E!

5m@ G H //// here G H@14

!g ) E!

5f@ f // /// here [email protected]!4; )@144m

? !g


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$rea of the pipea@"9.1323# d! @ " 9.1323#( [email protected]


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ased on the system head at di&erent A point; draw a system cur


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n the drawing; the intersection point between 5/A curve andystem curve is the ,P6$TIJ P,ITof the pump.

t the operating point; we can get:he discharge of the pump; A @ !1.= l2s

utput pressure head; 5 @ B.< m%ciency @

he power of the pump can be calculated by:

ower @ Kg A 5

@ 14!= g2m9( B.D1 m2s ( !1.= ( 14/9m92s ( B.

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