INTRODUCTION TO PUMPS, COMPRESSORS, FANS & BLOWERS.pdf

Pump compressor fan introduction

1. INTRODUCTION TO
PUMPS,
COMPRESSORS, FANS &
BLOWERS

2. There are two main categories of pump:
Rotodynamic pumps.
Positive displacement
pumps.
Diaphrag
m
Piston
Plunger
Reciprocatin
g
Rotary
Mixed
flow Gear
Lobe
Sliding
Vane
Screw
Axial flow
Centrifug
al
Rotodynami
c
Turbine
Positive
displacement
PUMP
2

3. PUMPS
Positive-Displacement
Pumps
Centrifugal
Pumps
Reciprocating Pump Rotary Pump
Devices used to
transport/move liquids
through pipes & channels.
pumps increase the mechanical
energy of the liquid, increasing its
velocity, pressure, or elevation-or
all three.
Piston
Plunger
Diaphragm
Gear
Lobe
Screw
Vane
Spur-GP
Internal-GP

4. CentrifugalPumps:
centrifugalpumpshavearotatingimpeller,alsoknownasa
blade,thatisimmersedintheliquid.Liquidentersthepump
neartheaxisoftheimpeller,andtherotatingimpellersweeps
theliquidouttowardtheendsoftheimpellerbladesathigh
pressure.
Forlowflowsandhighpressures,theactionoftheimpeller
islargelyradial.
Positive-displacementPumps:
Avarietyofpositive-displacementpumpsarealsoavailable,
generallyconsistingofarotatingmemberwithanumberof
lobesthatmoveinaclose-fittingcasing.Theliquidistrappedin
thespacesbetweenthelobesandthendischargedintoaregion
ofhigherpressure.Acommon deviceofthistypeisthegear
pump,whichconsistsofapairofmeshinggears.Thelobesin
thiscasearethegearteeth
3

5. Themaindifferencebetweenkineticandpositivedisplacement
pumpsliesinthemethodoffluidtransfer.
Whatisthemaindifferencebetweenkineticandpositive
displacementpumps?
Akineticpumpimpartsvelocityenergytothefluid,whichis
convertedtopressureenergyuponexitingthepumpcasing
Apositivedisplacementpumpmovesafixedvolumeoffluidwithin
thepumpcasingbyapplyingaforcetomoveableboundaries
containingthefluidvolume.
4

6. POSITIVE-DISPLACEMENT PUMPS
2subclasses:reciprocatingpumps&rotarypumps.
Reciprocatingpumps:thechamberisstationarycylinder
thatcontainsapistonorplunger.
Rotarypumps:thechambersmovesfrominlettodischarge
andbacktotheinlet.
inlet discharge
inlet
discharge
chamber
chamber
gear
Reciprocating pumps Rotary pump

7. POSITIVE-DISPLACEMENT PUMPS:
RECIPROCATINGPUMPS
Pistonpump:
liquidisdrawnthroughaninletcheckvalveintothecylinderbythe
withdrawalofapiston.
thentheliquidisforcedoutthroughadischargeonthereturnstroke.
inlet
discharge
chamber
Single-acting
Piston
Check valve

8. Pistonpump:

9. POSITIVE-DISPLACEMENT PUMPS:
RECIPROCATINGPUMPS
Double-acting
Piston
Check valve
mostpistonpumpsaredouble-actingwithliquidadmittedalternatelyoneach
sideofthepistonsothatonepartofthecylinderisbeingfilledwhiletheother
isbeingemptied.
thepistonmaybemotor-driventhroughreducinggearorasteamcylinder
maybeusedtodrivethepistonroddirectly.
max.dischargepressureforcommercialpistonpumpsisabout50atm.
inlet
discharge
chamber

10. DoubleActingPistonPump:

11. POSITIVE-DISPLACEMENT PUMPS:
RECIPROCATINGPUMPS
Plunger pump:
areusedforhigherpressures.
insteadofusingpistonsandpistonrings,theymakeuseoffinelymachined
plungersofverysmallclearancesinordertosealtheliquidtobepumped.
theplungersarehighlypolishedandmaderelativelylongsothatonlyvery
littleliquidcanescapethroughtheclearances.
atthelimitofitsstroke,theplungerfillsnearlyallthespaceinthe
cylinder.
aresingle-actingandusuallyaremotordriven.
theycandischargeagainstapressureof1500atmormore.
inlet
discharge
chamber

12. Plunger pump:

13. POSITIVE-DISPLACEMENT PUMPS:
RECIPROCATINGPUMPS
Diaphragm pump:
the reciprocating member is a flexible diaphragm of
metal, plastic & rubber.
diaphragm pumps handle small to moderate amounts of
liquid, up to about 100 gal/min, can develop pressures in
excess of 100 atm.

14. POSITIVE-DISPLACEMENT PUMPS:
RECIPROCATINGPUMPS
Diaphragm pump:

15. POSITIVE-DISPLACEMENT PUMPS:
ROTARYPUMPS
Unlikereciprocatingpumps,rotarypumpscontainnocheck
valves.
Minimizeleakagefromthedischargespacebacktothesuction
space;theyalsolimittheoperatingspeed.
Rotarypumpsoperatebestonclean,moderatelyviscousfluids
suchaslightlubricatingoil.
Dischargepressuresupto200atmormorecanbeattained.
inlet discharge
chamber
gear
Rotary pump

16. POSITIVE-DISPLACEMENT PUMPS:
ROTARYPUMPS
Spur-gear pump
Intermeshinggearsrotatewithcloseclearanceinsidethecasing.
Liquidenteringthesuctionlineatthebottomofthecasingiscaughtin
thespacesbetweentheteeth&thecasing&iscarriedaroundtothetop
ofthecasing&forcedoutthedischarge.
liquidcannotshort-circuitbacktothesuctionbecauseoftheclose
meshingofthegearsinthecenterofthepump.
inlet discharge
chamber
gear
Spur-gear pump

17. Spur-gear pump

18. POSITIVE-DISPLACEMENT PUMPS:
ROTARYPUMPS
Internal-gear pump
Aspurgearorpinionmesheswitharinggearwithinternalteeth.
Bothgearsareinsidethecasing.
Theringgeariscoaxialwiththeinsideofthecasing,butthepinion,
whichisexternallydriven,ismountedeccentricallywithrespecttothe
centerofthecasing.
Astationarymetalcrescentfillsthespacebetweenthetwogears.
Liquidiscarriedfrominlettodischargebybothgears,inthespaces
betweenthegearteethandthecrescent.
Internal-gear pump

19. Internal-gear pump

20. POSITIVE-DISPLACEMENT PUMPS:
ROTARYPUMPS
Lobe pump

21. Vane pump

22. POSITIVE-DISPLACEMENT PUMPS:
ROTARYPUMPS
Screw pump

23. 1-Casing:-
II. Circular casings for low head and high capacity.
A volute is a curved funnel increasing in area to the
discharge port.
Volute
SuctionImpeller
Construction of Centrifugal Pumps
Casing generally are two types:
I. Volute casings for a higher head.
have stationary diffusion vanes surrounding the
impeller periphery that convert velocity energy to
pressure energy.
6

24. RadialflowAxial flow
Mixed flow
2-Impeller
Three main categories of centrifugal pumps exist
7

25. CENTRIFUGAL PUMPS
Thesecondmajorclassofpumps,wheremechanicalenergyoftheliquidis
increasedbycentrifugalaction.
Theliquidentersthroughasuctionconnectionconcentricwiththeaxisofa
high-speedrotaryelementcalledtheimpellerwhichcarriesradialvanes
integrallycastinit.
Liquidflowsoutwardinthespacesbetweenthevanesandleavesthe
impelleringreatervelocitywithrespecttothegroundthanattheentrance
totheimpeller.
Inaproperlyfunctioningpump,thespacebetween
thevanesiscompletelyfilledwithliquidflowing
withoutcavitation.
Theliquidleavingtheouterperipheryofthe
impelleriscollectedinaspiralcasingcalledthe
voluteandleavesthepumpthroughatangential
dischargeconnection.
Inthevolute,thevelocityheadoftheliquidfrom
theimpellerisconvertedtopressurehead.

26. CENTRIFUGAL PUMPS
•Thepowerisappliedtothefluidbytheimpellerandistransmittedto
theimpellerbythetorqueofthedriveshaft,whichusuallyisdrivenby
direct-connectedmotoratconstantspeed,commonlyat1750or3450
r/min.
Centrifugalpumpsconstitutethemostcommontypeofpumping
machineryinordinaryplantpractice.
Acommontypeusesadouble-suctionimpeller,whichacceptsliquidfrom
bothsides.

27. CENTRIFUGAL PUMPS
Single-suction centrifugal pump

28. PUMPPERFORMANCE CURVE
A mapping or graphing of the pump's ability to
produce head and flow

29. PUMPPERFORMANCE CURVE
STEP#1, HORIZONTALAXIS
The pump's flow rate is plotted on the
horizontal axis ( X axis)
Usually expressed in Gallons per Minute
Pump Flow Rate

30. PUMPPERFORMANCE CURVE
STEP#2, VERTICALAXIS
Pump Flow Rate
The head the pump produces is
plotted on the vertical axis (Y axis)
Usually express in Feet of Water
Head

31. PUMPPERFORMANCE CURVE
STEP#3, MAPPINGTHEFLOWANDTHEHEAD
Pump Flow Rate
Most pump
performance curves
slope from left to
right
Performance Curve
Head

32. PUMPPERFORMANCE CURVE
IMPORTANTPOINTS
Shut-off Head is the maximum
pressure or head the pump can
produce
No flow is produced
Pump Flow Rate
Head
Shut-off Head

33. PUMPPERFORMANCE CURVE
IMPORTANTPOINTS
Pump Flow Rate
Head
Maximum Flow
Maximum Flow is the
largest flow the pump can
produce
No Head is produced

34. SYSTEMPERFORMANCE CURVES
System Performance Curve is a mapping of the
head required to produce flow in a given system
A system includes all the pipe, fittings and
devices the fluid must flow through, and
represents the friction loss the fluid experiences

35. SYSTEMPERFORMANCE CURVE
STEP#1, HORIZONTALAXIS
System Flow Rate
The System's flow rate in plotted on the
horizontal axis ( X axis)
Usually expressed in Gallons per Minute

36. SYSTEMPERFORMANCE CURVE
STEP#2, VERTICALAXIS
Pump Flow Rate
The head the system requires is plotted
on the vertical axis (Y axis)
Usually express in Feet of Water
Head

37. SYSTEMPERFORMANCE CURVE
STEP#3, CURVEMAPPING
The friction loss is mapped onto the graph
The amount of friction loss varies with flow
through the system
Head
Pump Flow Rate
Friction Loss

38. Head
Pump Flow Rate
The point on the system curve that intersects
the pump curve is known as the operating
point.

39. Head
Pump Flow Rate
Circulator 1
Circulator
2
Circulator 3
PUMP SELECTION

40. CONTROLLINGPUMPPERFORMANCE
Changing the amount for friction loss or "Throttling
the Pump" will change the pump's performance

41. Head
Pump Flow Rate
PUMP SELECTION
Valve Open
Valve Partially Open
Valve Barely Open

43. Onceagain,imaginestartingapumpandraisingthefluidina
verticaltubetothepointofmaximum elevation.Onthecurvethis
wouldbemaximum headatzeroflow.Now,rotatetherunningpump
onitscenterline90°,untiltheverticaltubeisnowinahorizontal
position.
H-Q Carve
8

44. Family curves
Attimesyou’llfindthattheinformationisthesame,butthepresentationofthe
curvesisdifferent.Almostallpumpcompaniespublishwhatarecalledthe‘family
ofcurves’.Thepumpfamilycurvesareprobablythemostusefulforthe
maintenanceengineerandmechanic,thedesignengineerandpurchasingagent.
Thefamilycurvespresenttheentireperformancepictureofapump.
9

45. Heads of Pump:
where :
V
s= Velocity of fluid in the suction pipe.
V
d= Velocity of fluid in the delivery
pipe.
h
s= Suction head.
h
d= Delivery head.
h
fs= head losses in the suction pipe.
h
fd= head losses in the delivery pipe.
10
Static head (H
st)
H
st= h
s+ h
d

46. Manometrichead (H
m) :)(
sd
sd
m
zz
pp
H 



butfd
h
d
h
d
p

 and)(
fss
s
hh
p

 )2(
2
gV
D
L
fh
dfd = Hst + hf + g
V
s
2
2
where h
f= h
fs+ h
fdL
w
Lm
H
g
UV
HhH 
22
(where H
L= impeller losses)
Total head (H)g
VV
zz
pp
H
sd
sd
sd
2
)(
22




 H = hs + hfs + hd + hfd + g
V
d
2
2
(where ) = Hst + hf + g
V
d
2
2 Hm = H + )(
2
1
22
dsVV
g

When V
s= V
d
Hence H
m= H
11

47. There are three main categories of impeller due type of impeller’s vane, which
are used in the centrifugal pumps as;
Radial vanes, Fig. (a).
Backward vanes, Fig. (b).
Forward vanes, Fig. (c).
12
Typeof Impeller

48. a) when β
2> 90
o
, the Forwards curved
vanes of the impeller.
b) when β
2= 90
o
, the radial curved vanes
of the impeller.
c) when β
2< 90
o
, the Backwards curved
vanes of the impeller.
where :
V=absolute velocity of the water.
U= Tangential velocity of impeller (peripheral velocity).
V
r
= relative velocity of water to the wheel.
V
f
= velocity flow.
N= Speed of impeller in (rpm). = vane angle. 
= angle at which water leaves.
13

49. Pump Efficiencies
1-Hydraulic Efficiency (ζ
h) )(
)('
e
h
HHeadEuler
HHeadTotalsPump
 22
UV
gH
w
h
The normal value varies between 60% -90%
2-Manometric Efficiency(ζ
m))(
)('
e
m
m
HHeadEuler
HHeadManometricsPump
 22
UV
gH
w
m
m
3-Volumetric Efficiency (ζ
v)QQ
Q
v


The normal value lies between 97% to 98%
14

50. 4-Mechanical Efficiency (ζ)
It is due to losses in the shaft, coupling, and other operation losses as vibration


shafttheatPower
impellerthetoinPower
 ShaftPower
UVQQ
w

)(
22



The normal value is 95% -98%
5-Overall Efficiency (ζ
o) 


.T
QH
P
P
in
out
o  hQQ
QH
P
P
P
P
P
P
lin
t
in
t
t
out
o


)(

 hvmo
 
The normal value is 71% -86%
Discharge of a Centrifugal Pump222111 ff
VbDVbDQ  
15

51. 6-Power Required to Drive a Centrifugal Pumpo
QH
P


750

(hp)750
11
g
UQV
P
w

 (hp)
7-1 Cavitation
Cavitationisdefinedasthephenomenon offormationofvaporbubblesofflowing
liquidinaregionwherethepressureoftheliquidfallsbelowitsvaporpressure
andthesuddencollapsingofthisvaporbubblesinaregionofhigherpressure.
Whenthevaporbubblescollapse,averyhighpressureiscreated.Theformation
andthecollapseofagreatnumberofbubblesonthesurfaceproduceintenselocal
stressesthatdamagethesurfacebyfatigue.Itmayoccurattheentrytopumpsorat
theexitfromhydraulicturbinesinthevicinityofthemovingblades
16
Thecavitationphenomenon developsintheimpellerpump,whenthepressureof
liquidfallsbelowthesaturatedvaporpressureattheprevailingtemperature(P
s<P
v
ofliquid),smallvaporbubblesbegintoformandthedissolvedgasesareevolved.
Thevaporbubblesarecaughtupbythefollowingliquidandsweptintoaregionof
higherpressure,wheretheycondense.Condensation takesplaceviolently,
accompaniedbyatremendousincreaseinpressure,whichhasthecharacterof
waterhammerblows.Theseimpactfolloweachotherinrapidsuccession,thevapor
bubblesburstingbothintheimmediatevicinityofthesurfaceattackedandinthe
porescausingcavitationpittingwithmanyeffecting.
7-2 Cavitation processes in centrifugal pump

52. Rotary PumpsReciprocating PumpsCentrifugal PumpsParameter
Low/Medium Capacity,
Low/Medium Pressure
Low Capacity,
High Pressure
Medium/High Capacity,
Low/Medium Pressure
Optimum Flow and
Pressure Applications
10,000+ GPM10,000+ GPM100,000+ GPMMaximum Flow Rate
YesYesNoLow Flow Rate Capability
4,000+ PSI100,000+ PSI6,000+ PSIMaximum Pressure
YesYesNoRequires Relief Valve
SmoothPulsatingSmoothSmooth or Pulsating Flow
ConstantConstantVariableVariable or Constant Flow
YesYesNoSelf-priming
Requires Less SpaceRequires More SpaceRequires Less SpaceSpace Considerations
Lower Initial
Lower Maintenance
Lower Power
Higher Initial
Higher Maintenance
Lower Power
Lower Initial
Lower Maintenance
Higher Power
Costs
Requires clean, clear, non-
abrasive fluid due to close
tolerances
Optimum performance with
high viscosity fluids
Higher tolerance for
entrained gases
Suitable for clean, clear, non-
abrasive fluids.Specially-
fitted pumps suitable for
abrasive-slurry service.
Suitable for high viscosity
fluids
Higher tolerance for
entrained gases
Suitable for a wide range
including clean, clear, non-
abrasive fluids to fluids with
abrasive, high-solid content.
Not suitable for high viscosity
fluids
Lower tolerance for entrained
gases
Fluid Handling
TheTablebelowoutlinessomeofthemaindifferencesbetweencentrifugalpumps,
reciprocatingpumpsandrotarypumps.Notethat“centrifugal”,“reciprocating”
and“rotary”pumpsareallrelativelybroadcategories
5

53. Formulasfor Refiguring Pump Performance with Impeller Diameter
or Speed Change
Diameter and Speed
Change
Speed ChangeOnlyDiameter Change Only
8-The Affinity Law
17
References:
1-Larry Bachusand Angel Custodio, (2003). Know and Understand Centrifugal Pumps.
2-Val S. LobanoffRobert R. Ross, (1992). Centrifugal Pumps -Design and Application (2
nd
ed.)
3-Igor J. Karassik,osephP. Messina,PaulCooper and Charles C. Heald,2001. Pump Handbook(3
rd
ed)

55. COMPRESSORS,
BLOWERS
& FANS

56. COMPRESSORS & BLOWERS, FANS
aremachinesthatmove&compressgases.
1.Fansdischargelargevolumesofgas(usually
air)intospacesorlargeducts
-arelow-speedmachinesthatgeneratevery
lowpressures,ontheorderof0.04atm.
2.Blowers:arehigh-speedrotarydevices
(usingeitherpositivedisplacementorcentrifugal
force)thatdevelopamax.pressureofabout2
atm.
3.Compressors:arealsopositive-displacementor
centrifugalmachines,dischargeatpressurefrom
2atmtoseveralthousandatmospheres.

57. DIFFERENCES BETWEEN FANS, BLOWERS
& COMPRESSORS
Equipment Specific Ratio Pressure rise
(mmWg)
Fans Up to 1.11 1136
Blowers 1.11-1.20 1136-2066
Compressors
More than 1.20 -
Ratio of discharge
pressure over suction
pressure

58. COMPRESSORS
Positive-displacement compressors
Rotarypositive-displacementcompressorscanbeusedfor
dischargepressuresuptoabout6atm.
Thesedevicesincludesliding-vane,screw-type,andliquid
pistoncompressors.
Forhightoveryhighdischargepressures&modestflow
rates,reciprocatingcompressorarethemostcommontype.
Thesemachinesoperatemechanicallyinthesamewayas
reciprocatingpumps,withthedifferencesthatleak
preventionismoredifficultandtemperatureriseis
important.
Thecylinderwalls&cylinderheadsarecoredforcooling
jacketsusingwaterrefrigerant.
Reciprocatingcompressorsareusuallymotor-driven&nearly
alwaysdoubleacting.

59. COMPRESSORS
Reciprocating compressor

60. COMPRESSORS
Centrifugal compressors
aremultistageunitscontainingaseriesofimpellersonasingle
shaftrotatingathighspeedsinmassivecasing.
internalchannelsleadfromthedischargeofoneimpellertothe
inletofthenext.
thesemachinescompressenormousvolumesofairorprocess
gas-upto200,000ft
3
/min(340,000m
3
/h)attheinlet-tooutlet
pressureof20atm.
smaller-capacitymachinesdischargeatpressuresuptoseveral
hundredatmospheres.
interstagecoolingisneededonthehigh-pressureunits.
axial-flowmachineshandleevenlargervolumesofgasupto600,000
ft
3
/min(1x10
6
m
3
/h),butatlowerdischargepressuresof2to12
atm.
intheseunitstherotorvanespropelthegasaxiallyfromonesetof
vanesdirectlytothenext.Interstagecoolingisnormallynot
required.

61. Compressors
Interior of centrifugal compressor

62. BLOWERS
Positive-displacementblower
Thesemachinesoperatesasgearpumpsdo
exceptthat,becauseofthespecialdesignofthe
“teeth",theclearanceisonlyafewthousandths
ofaninch.
therelativepositionoftheimpellersis
maintainedpreciselybyheavyexternalgears.
Asingle-stageblowercandischargegasat0.4to
1atmgauge,atwo-stageblowerat2atm.
Example:positive-displacementtwo-lobeblower.

63. BLOWERS
Positive-displacement two-lobe blower

64. BLOWERS
Centrifugalblowers
Inappearanceitresemblesacentrifugalpump,
exceptthatcasingisnarroweranddiametersofcasing&
dischargescrollarerelativelylargerthanincentrifugal
pump.
Theoperatingspeedishigh-3,600r/minormore.
Highspeedandlargeimpellerdiametersarerequired
becauseveryhighheadsoflow-densityfluidsareneeded
togeneratemodestpressureratios.
Thus,thevelocityapproximately10timesthosein
centrifugalpump.
Example:single-suctioncentrifugalblower

65. BLOWERS
Single-suction centrifugal blower

66. FANS
Large fans usually centrifugal, operating exactly
the same principle as the centrifugal pumps.
Their impeller blades may be curved forward,
this would lead to instability in a pump, but not
in a fan.
The impellers are mounted inside light sheet-
metal casings.
Clearances are large & discharge heads low, from
5 to 60 in. (130 to 1500 mm) H2O.
Sometimes, as in ventilating fans, nearly all the
added energy is converted to velocity energy and
almost none to pressure head.

67. FANS
Impellers for centrifugal fans

68. CAVITATION
https://youtu.be/2k1NRCRVZZM