Dr. Ahmed Abdel-NabyDr. Ahmed Abdel-NabyFluid Mechanics & Hydraulic Fluid Mechanics & Hydraulic

MachinesMachinesMech. Eng. Dept.Mech. Eng. Dept.

Faculty of EngineeringFaculty of EngineeringAlexandria Univ.Alexandria Univ.

email: hydrocareeg@hotmail.comemail: hydrocareeg@hotmail.com

Table of Contents

Chapter One:

• Fluid Properties • Density• Viscosity • Vapor pressure## Governing equations • Continuity equation • Bernoulli’s equation • Energy per unit weight • Friction Head Losses • Minor Losses • Loss coefficients for pipe components

Chapter Two:

• Classification of pumps Pump terminology

• System Characteristics and Pump Head • Total dynamic head • Power • Pump Performance curves • Net positive suction head (NPSH) • Affinity laws • Effect of fluid viscosity• Flow, head and power coefficients • Understanding the System Head Curves • Variants in Pumping Systems

Chapter Three:

• Centrifugal Pump Construction • Classification • Casings • Radial Thrust • Impellers • Impeller Mechanical Types • Wearing Rings • Axial Thrust • Axial Thrust in Multi-Stage Pumps• Shafts and Shaft Sleeves • Mechanical Seals

Chapter Four:

• Centrifugal Pump Performance • Characteristic Curves (Pump Theory) • Real & Ideal Fluid • Performance parameters (Affinity Laws) • Specific Speed • Modifications to Impeller and Casing • Reduction of Cavitation Damage • Pump Selection • Priming • Capacity Regulation • Parallel and series Operation • Operation at Other than Normal Capacity

Pump Cavitation:

• Pump Cavitation • Concept of Cavitation• Mechanism of Cavitation • General Symptoms of Cavitation

Chapter Five:

## Installation and Operation: • Installation • Foundations • Alignment • Grouting

## Piping:• Suction Piping • Discharge Piping • Piping Strains • Expansion Joints

## Operation: • Pre-Operational Checks • Starting and Stopping Procedures • The pump in operation • Diagnosing pump and Seal Problems in Field • Pump Preventive maintenance

Chapter Six:

• Maintenance • Daily observation of pump operation • Semi-annual inspection • Annual Inspection • Spare and repair parts • Diagnosis of Pump Problems • Centrifugal Pump Hydraulic performance Diagnostics• Cavitation • Suction and Discharge Recirculation • Axial Thrust • Radial Thrust

Chapter Seven (Applications)

• Pumps in Petroleum Industry • Refinery Pumps • Construction • Performance • Materials • Drives • Pipeline Pumps • Construction• Performance • Materials • Special services: Water-flood • Reactor Feed Pumps • Pumping of Viscous Liquid

Chapter Eight

Positive-Displacement Pumps • Vane Pumps • Gear Pumps • Piston pumps • Radial piston pumps • Axial piston pumps • Screw Pumps

• Pump Efficiencies • Performance • Trouble shooting

Chapter One

Fluid PropertiesFluid Properties

Density(Density(ρρ): ): it is the it is the mass per unitmass per unit

volumevolume

ρρ = mass/volume = M/v = mass/volume = M/v (Kg/m(Kg/m33))

ρρ for water ( for water (ρρww = 1000 kg/m= 1000 kg/m33) at 4) at 4oo c c

Specific Weight(Specific Weight(γγ):): defined as Weigh per unit volume defined as Weigh per unit volume γγ = weight/ volume = W/V ( N/m = weight/ volume = W/V ( N/m33 ) ) γγ = = ρρ g g

γγ for water ( for water (γγww = 9800 N/m = 9800 N/m33 ) )

Specific Gravity (S.G.):Specific Gravity (S.G.):

defined as the ratio of the density of the fluid to the defined as the ratio of the density of the fluid to the density of water at some specified temperature density of water at some specified temperature

S.G. =S.G. = ρρf f / / ρρww

ViscosityViscosity (µ): (µ): Fluid ability to resist motionFluid ability to resist motion

dy

du

Dynamic viscosity ,Dynamic viscosity ,μμ, in:, in:N.s/ mN.s/ m2 2 or Pa.s or Kg/m.s or Pa.s or Kg/m.sor poise ( dyne.s/cmor poise ( dyne.s/cm22 ) )

Kinematic viscosity , Kinematic viscosity , νν , in:, in:mm22/s or stokes or centi-/s or stokes or centi-stokesstokes

/v

Vapor Pressure ( PVapor Pressure ( Pvap vap ):):

It is the pressure at which liquid starts to It is the pressure at which liquid starts to evaporate at working temperature.evaporate at working temperature.

Pour PointPour Point

It is the temperature at which the fluid It is the temperature at which the fluid (petroleum product or crude) seems to be (petroleum product or crude) seems to be freeze.freeze.

Governing equations of compressible & Governing equations of compressible & incompressible flowincompressible flow 1.1. Continuity equation.Continuity equation.

Where G is the mass flow rateWhere G is the mass flow rate Q is the volume flow rate or Q is the volume flow rate or

dischargedischarge

ρQρAVG

AVQ

For steady flow:For steady flow:

21 GG 222111 VAVA

21 QQ 2211 VAVA

AQV /

2.2. Bernoulli's EquationBernoulli's Equation..

E = P/E = P/ρρg + Z + Vg + Z + V22/2g/2gWhere:Where:

E=Total energy/unit weightE=Total energy/unit weightZ= Potential energy/unit Z= Potential energy/unit

weight weight P/P/ρρg= pressure energy/ unit g= pressure energy/ unit weightweight

vv22/2g = kinetic energy/unit /2g = kinetic energy/unit weightweight

For ideal fluid:For ideal fluid:EE11 =E =E22

For real fluid:For real fluid:

EE11 = E = E22 + losses + losses

gVpzgVpz 2//2//2

222

2

111

LhgVpzgVpz 2//2//

2

222

2

111

Losses in pipes

Major loss( Friction loss)

Minor loss( Eddy loss )

I-FRICTION LOSS

Due to friction( along the pipe-straight pipes ) i- Friction between fluid layers

( laminar flow )

ii- Friction between fluid and pipe walls ( turbulent flow )

Reynolds numberReynolds number ( R ( RN N ))

RRNN = = ρρvd/vd/μμ

RRN N < 2000 Laminar Flow< 2000 Laminar FlowRRN N > 4000 Turbulent > 4000 Turbulent

FlowFlow2000 < R2000 < RN N < 4000 Transition < 4000 Transition

FlowFlow

DARCY EQUATION The completely general functional

relation

τw= fn (V, D, ρ, µ, e)

where: The wall shear stress τw The mean velocity V, Pipe diameter D, Fluid density ρ, Fluid viscosity µ, Pipe roughness e or ξ

f = 64/Rf = 64/RN N for Laminar flowfor Laminar flow

f from Moddy Chart for Tur. f from Moddy Chart for Tur. flowflow

2

22

22 gA

Q

D

Lf

g

V

D

Lfh f

II-Minor LossesII-Minor Losses

Due to change in velocity vectorDue to change in velocity vector(at certain section)(at certain section)

i-i- change in velocity magnitudechange in velocity magnitude

( due to area change )( due to area change )

ii-ii- change in velocity direction change in velocity direction

( bends)( bends)

iii-iii- change in velocity magnitude & change in velocity magnitude & direction ( see examples )direction ( see examples )

i-i- change in velocity change in velocity magnitudemagnitude

( due to area change )( due to area change )

Sudden enlargementSudden enlargementhhL1-2 L1-2 =k=kLL ( v ( v11-v-v22))22/2g/2g

Gradual enlargementGradual enlargement hhL1-2 L1-2 =k=kLL v v11

22/2g/2g

Sudden contractionSudden contraction

h hL1-2 L1-2 =k=kLL v v2222/2g/2g

Entrance flowEntrance flow conditions and loss coefficientconditions and loss coefficient((aa) Reentrant, ) Reentrant, KLKL= 0.8, = 0.8, ((bb) sharp-edged, ) sharp-edged, KLKL= 0.5, = 0.5, ((cc) Slightly rounded,) Slightly rounded, KL KL=0.2 =0.2 ((dd) well-rounded, ) well-rounded, KLKL= 0.04= 0.04

Flow pattern and pressure Flow pattern and pressure distribution for a sharp-edged distribution for a sharp-edged

entranceentrance

Exit flow conditions and loss coefficientExit flow conditions and loss coefficient ((aa)) ReentrantReentrant, , KLKL= 1.0, = 1.0, (b)(b) sharp-edgedsharp-edged, , KLKL= 1.0 = 1.0 (c)(c) SlightlySlightly roundedrounded, , KLKL= 1.0 = 1.0 (d)(d) wellwell--roundedrounded, , KLKL= 1.0= 1.0

ii-ii- change in velocity directionchange in velocity direction( bends )( bends )

hhLb Lb =k=kbb v v22/2g/2g k kbb depends on R,D,depends on R,D,ξξ

Loss in valvesLoss in valves h hLv Lv =k=kvv v v22/2g/2g k kvv depends on valve typedepends on valve type

valve openingvalve opening

Valve Types:Valve Types:((aa) Globe valve, ) Globe valve, ((bb) Gate valve, ) Gate valve, ((cc) swing check valve, ) swing check valve, ((dd) Stop check valve.) Stop check valve.

Valve opening:Valve opening:

Loss Coefficients for Pipe Components a Loss Coefficients for Pipe Components a hhLL = = KKLL VV22/2/2gg

PipelinesPipelines

Transmission LinesTransmission LinesPetroleum EngineeringPetroleum Engineering

Transmission Lines For Petroleum Transmission Lines For Petroleum EngineeringEngineering

Petroleum Petroleum EngineeringEngineering

Transmission LinesTransmission LinesTransmissionTransmission

LinesLines

Transmission LinesTransmission Lines

TransmissionTransmission

LinesLinesTransmission Transmission LinesLines Side boom Side boom Side Side

boomboom

Transmission LinesTransmission Lines

Industrial ApplicationsIndustrial Applications

ValvesValves

ValvesValves

Gate ValvesGate Valves

Check ValvesCheck Valves

Butter Fly ValveButter Fly Valve

Piping & ValvesPiping & Valves

PumpsPumps

• Definition.Definition.

• Applications.Applications.

• Types.Types.

• Selection.Selection.

DefinitionDefinition

Pump is a Pump is a hydraulic hydraulic machinemachine used to convert used to convert mechanical powermechanical power into into

hydraulic powerhydraulic power

I/P O/PI/P O/P( Mech. Energy ) ( Hyd. ( Mech. Energy ) ( Hyd. Energy )Energy )

P

Hyd. Power = P Hyd. Power = P x x Q = Q = γγ x x Q Q x x HHmm

where:where:PP is the pump pressure is the pump pressure QQ is he pump flow rate is he pump flow rate γγ liquid specific weightliquid specific weightHHmm is the pump headis the pump head

Pump applicationsPump applications

• Lifting pump.Lifting pump.

• Circulating pump.Circulating pump.

• Boosting pump.Boosting pump.

Lifting PumpLifting Pump

HHst st ( +ve ) ( +ve ) + ve+ ve - ve- ve

suction (s) delivery suction (s) delivery (d)(d)

P

Circulating PumpCirculating Pump

HHstst ( 0 ) ( 0 )

P

Boosting PumpBoosting Pump

P HHstst ( -ve )( -ve )

Piping System Calculations:Piping System Calculations:

• Static suction head (hStatic suction head (hs.ss.s):): The static The static suction head is the difference in elevation suction head is the difference in elevation between the wet well liquid level and the between the wet well liquid level and the datum elevation of the pump impeller. If the datum elevation of the pump impeller. If the wet well liquid level is below the pump wet well liquid level is below the pump datum, so hdatum, so hss is negative. is negative.

• Static discharge head (hStatic discharge head (hss..dd):): The static The static discharge head is the difference in elevation discharge head is the difference in elevation between the discharge liquid level and the between the discharge liquid level and the pump datum elevation.pump datum elevation.

• Total static head (HTotal static head (Hstst):): The total static The total static head is the difference in elevation between head is the difference in elevation between the water level in the wet well and the water the water level in the wet well and the water level at discharge (hlevel at discharge (hdd -h -hss).).

• Friction head loss (hFriction head loss (hfsfs, h, hfdfd):): This is the This is the head of fluid that must be supplied to head of fluid that must be supplied to overcome the frictional loss in the pipe.overcome the frictional loss in the pipe.

• Velocity head (vVelocity head (v22/2g)/2g):: The velocity head is The velocity head is the kinetic energy in the liquid being the kinetic energy in the liquid being pumped at a point in the system.pumped at a point in the system.

• Total energy line (T.E.L.):Total energy line (T.E.L.): Shows the Shows the energy distribution along the piping system.energy distribution along the piping system.

• Hydraulic gradient line ( H.G.L.):Hydraulic gradient line ( H.G.L.): Shows Shows the pressure distribution along he piping the pressure distribution along he piping system.system.

• Manometric suction head (HManometric suction head (Hm.sm.s):): The suction gauge reading is expressed in meters The suction gauge reading is expressed in meters measured at the suction nozzle of the pump and measured at the suction nozzle of the pump and referenced to the pump datum elevation.referenced to the pump datum elevation.

• Manometric discharge head (HManometric discharge head (Hm.dm.d,):,): The The discharge gauge reading is expressed in meters discharge gauge reading is expressed in meters measured at the discharge nozzle of the pump and measured at the discharge nozzle of the pump and referenced to the centerline of the pump impeller. referenced to the centerline of the pump impeller. It is also the distance to the hydraulic grade line It is also the distance to the hydraulic grade line and pressure reference. and pressure reference.

• Manometric head (HManometric head (Hmm):): This is the This is the increase of pressure head, expressed in increase of pressure head, expressed in meters generated by the pump (meters generated by the pump (HHm.dm.d-H-Hm.sm.s). ).

• HHm.sm.s = H = Hs.ss.s – h – hlsls - v - vss22/2g/2g

• HHm.dm.d = H = Hs.ds.d +h +hldld

• HHmm = H = Hm.dm.d - H - Hm.sm.s

• HHmm = (H= (Hs.ds.d +h +hldld ) – ( H) – ( Hs.ss.s – h – hlsls - v - vss22/2g )/2g )

• HHmm = = (H(Hs.ds.d - H - Hs.s s.s ) + (h) + (hld ld + h+ hls ls ) + v) + vss22/2g/2g

• HHmm = H = Hs.ts.t + h + hltlt + v + vss22/2g/2g

Piping system curve:Piping system curve:

• HHmm = H = Hs.ts.t + ∑ h + ∑ hltlt + v + vss22/2g/2g

• HHmm = H= Hs.ts.t + KQ + KQ22

PowerPower

• Output PowerOutput Power

• The power output of a pump is the energy delivered by the The power output of a pump is the energy delivered by the pump to the fluid. pump to the fluid.

• In SI units, In SI units, P = P = Q H Q Hmm/c/c

• Where Where P P is the water power in is the water power in kWkW, , is the specific weight of the fluid in is the specific weight of the fluid in N/mN/m33, ,

QQ is the flowrate in is the flowrate in mm33/s/s, , HHmm is the total dynamic head in is the total dynamic head in mm, , CC is the unit constant ( 1000 )is the unit constant ( 1000 )

Input PowerInput Power• PumpPump performanceperformance is measured in terms of the is measured in terms of the

flow rateflow rate that a pump can discharge against a given that a pump can discharge against a given headhead at a given at a given efficiencyefficiency..

• The The pumppump capacitycapacity depends on the depends on the designdesign, and , and

design information of the pump design information of the pump manufacturer manufacturer in a in a series of curves for a given pump.series of curves for a given pump.

• Pump Pump efficiencyefficiency, , ήή , , is the is the ratioratio of the of the useful useful power outputpower output (water kilowatts [ (water kilowatts [kWkW] or water ] or water horsepower [horsepower [hphp]) to the ]) to the power inputpower input to the pump to the pump shaft. shaft.

• The The brake powerbrake power ( (bkWbkW) or the ) or the shaft powershaft power that that must be must be supplied bysupplied by the the drivedrive is, is,

PPshsh= = QH QHmm/C /C ήή

Pump efficiencyPump efficiency

• Pump efficiencyPump efficiency is defined as the is defined as the ratioratio between between the the outputoutput power and power and inputinput power which is power which is usually usually range range from from 20 to 85%20 to 85%..

• Pump efficiencyPump efficiency increasesincreases with the with the sizesize of the of the

pumppump.. • Energy lossesEnergy losses in a in a pumppump are: are: Volumetric Volumetric, ,

Mechanical, Mechanical, and and

HydraulicHydraulic

• Volumetric lossesVolumetric losses are those of are those of leakageleakage through the small through the small clearances clearances between between wearing ringswearing rings in the in the pump casingpump casing and and the the rotatingrotating elementelement. .

• Mechanical lossesMechanical losses are caused by are caused by mechanical frictionmechanical friction in the in the stuffing boxesstuffing boxes and and bearingsbearings, by , by internalinternal disc disc frictionfriction, and by, and by fluid shearfluid shear. .

• FrictionalFrictional and and eddy losseseddy losses within the flow within the flow passages account for the passages account for the hydraulic losseshydraulic losses..

Pump TypesPump Types

Roto-dynamicPumps1. Centrifugal pump2. Propeller pump

Positive Pumps

Reciprocating P.P. Rotary P.P.

1. Piston Pump 1. Gear Pump2. Diaphragm Pump 2. Screw Pump

3. Vane Pump 4. Parallel cylinder piston pump

Non-Mech. Pumps1. Jet pump2. Air lift pump

1- Roto-dynamic Pressure 1- Roto-dynamic Pressure PumpsPumps

• PumpsPumps are are divided intodivided into threethree groupsgroups::

• • Radial-flowRadial-flow pumps pumps • • MixedMixed--flowflow pumps pumps • • AxialAxial--flowflow or or propellerpropeller pumpspumps..

• These These classificationsclassifications are are derived derived

fromfrom the the mannermanner in whichin which the the fluid fluid moves through the pump moves through the pump (see (see Fig.Fig.).).

(a) Radial flow, Vertical (b) Mixed flow

(c) Radial flow, Horizontal (d) Axial flow

Centrifugal pump (end suction)

Centrifugal pumpCentrifugal pump

Axial Flow Axial Flow PumpPump

Pump Performance CurvesPump Performance Curves

• The The performanceperformance of a of a centrifugal pumpcentrifugal pump can be shown can be shown graphicallygraphically on on characteristic curves. characteristic curves.

• A A typical characteristic curve showstypical characteristic curve shows the: the:

• Total dynamic headTotal dynamic head, , • Brake horsepowerBrake horsepower, , • EfficiencyEfficiency, and, and• NNet et PPositive ositive SSuction uction hhead ead • All plotted over the All plotted over the capacitycapacity range of the range of the

pump ( Q ). pump ( Q ).

Understanding the Pipe system curveUnderstanding the Pipe system curve

Positive static headPositive static head

Zero static head, all frictionZero static head, all friction

Negative (Gravity) headNegative (Gravity) head

Most lift – Little friction headMost lift – Little friction head

Importance of Pipe system Importance of Pipe system

curvecurve • Every pump Every pump manufacturermanufacturer would like to would like to

recommend the recommend the perfect pumpperfect pump for any application. for any application. • To do this he would like the To do this he would like the contracting companycontracting company

to provide him with an to provide him with an accurate system curveaccurate system curve that would describe the that would describe the capacitycapacity and and head head neededneeded for various operating conditions. for various operating conditions.

• Once he has the system curve, he can Once he has the system curve, he can plotplot his his

pump curvespump curves on top of the on top of the system curvesystem curve and and hopefully select something that will come close to hopefully select something that will come close to the line needs. the line needs.

• Without this systemWithout this system curve curve, neither one , neither one of them have much of a chance of coming of them have much of a chance of coming up with the right pump.up with the right pump.

• To create a system curveTo create a system curve we plot the we plot the desired capacities against the required desired capacities against the required head over the total operating range of the head over the total operating range of the pump. pump.

VARIANTS IN PUMPING SYSTEMSVARIANTS IN PUMPING SYSTEMS• In practiceIn practice, conditions in a , conditions in a system varysystem vary as a result of as a result of

either controllable or uncontrollable either controllable or uncontrollable changeschanges.. • ExamplesExamples of either of either controllablecontrollable or or uncontrollableuncontrollable

system changessystem changes inin::

Valve openingValve opening in the pump in the pump dischargedischarge or or bypass bypass lineline, ,

SuctionSuction or or dischargedischarge liquid liquid levellevel,,

Pressures at these levels,Pressures at these levels,

AgingAging of pipes, of pipes,

Process, Number of pumpsProcess, Number of pumps pumping into pumping intocommon header, common header, Size, length, or number of Size, length, or number of

pipespipes

• These changesThese changes in system conditions: in system conditions:

Alter the shape of the system-head Alter the shape of the system-head curvecurve and, in turn, and, in turn, Affect pump flowAffect pump flow..

Variable Static HeadVariable Static Head

• In a system where a pump is taking In a system where a pump is taking suction from one reservoir and filling suction from one reservoir and filling another, the another, the capacitycapacity of a of a centrifugal pump will centrifugal pump will decreasedecrease with with an an increase in static head.increase in static head.

• If it is desired to If it is desired to maintain a constant maintain a constant pump flowpump flow for different static head for different static head conditionsconditions, the , the pump speed can be pump speed can be variedvaried to adjust for an increase or to adjust for an increase or decrease in the total system head.decrease in the total system head.

Variable System ResistanceVariable System Resistance • A A valve or valvesvalve or valves in the discharge linein the discharge line of a centrifugal pump of a centrifugal pump

alter the variable frictional head portion of the total system-head alter the variable frictional head portion of the total system-head curve and consequently the curve and consequently the pump flowpump flow..

• For example, the For example, the use ofuse of a a discharge valvedischarge valve to change the system to change the system

head for the purpose of head for the purpose of varying pump flowvarying pump flow during a shop during a shop performance test.performance test.

• The The maximum flowmaximum flow is obtained with a is obtained with a completely open valvecompletely open valve, ,

and the only resistance to flow is the friction in the piping, fittings, and the only resistance to flow is the friction in the piping, fittings, and flow meter. and flow meter.

• A A closed valveclosed valve results in: results in:## The pump’s operating at The pump’s operating at shutoff conditionsshutoff conditions and and

Produces Produces maximum headmaximum head..

## Any flow between maximum and shutoffAny flow between maximum and shutoff can can be be obtained by proper obtained by proper adjustmentadjustment of the of the valve openingvalve opening..

• It is important to It is important to select a pumpselect a pump that will have Its that will have Its best efficiencybest efficiency withinwithin the the operating rangeoperating range of the of the systemsystem

• And And preferablypreferably at the at the conditioncondition at at which the which the pump will operate most pump will operate most oftenoften..

CavitationCavitation

• When the When the pressurepressure of the liquid is reduced to a of the liquid is reduced to a value equal to or value equal to or below its vapor pressurebelow its vapor pressure the the liquid begins to boil and small vapor liquid begins to boil and small vapor bubbles or bubbles or pockets begin to formpockets begin to form..

• As these vapor bubbles move along the impeller As these vapor bubbles move along the impeller vanes to a higher pressure area above the vapor vanes to a higher pressure area above the vapor pressure, they pressure, they rapidly collapserapidly collapse..

• TheThe collapsecollapse is so rapid that it may be heard as is so rapid that it may be heard as a a noisenoise, as if you were pumping gravel. , as if you were pumping gravel.

• In high suction energy pumps, the collapses are In high suction energy pumps, the collapses are generally high enough to cause generally high enough to cause pockets of pockets of fatiguefatigue failurefailure on the impeller vane surfaces. This on the impeller vane surfaces. This action may be progressive, and under severe (very action may be progressive, and under severe (very high suction energy), conditions can cause serious high suction energy), conditions can cause serious pitting damagepitting damage to the impeller. to the impeller.

• The accompanying The accompanying noisenoise is the easiest way to is the easiest way to

recognize cavitation.recognize cavitation.

• Excessive cavitation results in Excessive cavitation results in reduced capacityreduced capacity due to the vapor present. due to the vapor present.

• In addition, the In addition, the headhead may be may be reducedreduced and/or be and/or be unstable and the unstable and the power consumption also power consumption also affected.affected.

• VibrationVibration and and mechanical mechanical damagedamage such as such as bearing failurebearing failure can also occur because of operating can also occur because of operating in excessive cavitation. in excessive cavitation.

• Cavitation causes :Cavitation causes : 1.1. Drop in QDrop in Q

2.2. Drop in HDrop in Hmm

3.3. Drop in eff.Drop in eff.

4.4. power consumption may be affected.power consumption may be affected.

5.5. PittingPitting

6.6. NoiseNoise

7.7. VibrationsVibrations

Impeller Impeller damageddamaged by cavitation by cavitation

How to prevent pump from How to prevent pump from cavitation?cavitation?To prevent the undesirable effects of cavitationTo prevent the undesirable effects of cavitation

is to insure that the is to insure that the minimum availableminimum available pressurepressure in the system is in the system is greater thangreater than the vapor the vapor pressurepressure..

P P minmin > P > P vap.vap. – P – P atm. atm.

H H minmin > h > h vap.vap. – h – h atm.atm.

H H ssss - h - h lsls- V- Vss22 / 2g – / 2g – σ σ HHmm > h > h vap.vap.– h – h atm.atm.

h h atmatm- h - h vapvap+H +H ssss- h - h ls ls > > σ σ HHmm+ + VVss22 / 2g / 2g

NPSHA > NPSHRNPSHA > NPSHR

• NNet et PPositive ositive SSuction uction HHead (ead (NPSHNPSH) NPSH ) NPSH AvailableAvailable is a function of the is a function of the systemsystem in which in which the pump operates.the pump operates.

• High suction energy pumpsHigh suction energy pumps RequireRequire an an additional additional NPSH marginNPSH margin, above the NPSH , above the NPSH Required. Required.

NPSHA > NPSHR + ( 1.2m to 2.5m )NPSHA > NPSHR + ( 1.2m to 2.5m )

NNet et PPositive ositive SSuction uction HHeadead( ( NPSH NPSH ))

Affinity LawsAffinity Laws• The affinity laws express the The affinity laws express the mathematical relationshipmathematical relationship

between the several variables involved in pump between the several variables involved in pump performance. performance.

• They They apply toapply to all types of all types of centrifugalcentrifugal and and axialaxial flow flow pumps. pumps.

## They are as follows: ## They are as follows:

1- 1- With impeller diameter D held constantWith impeller diameter D held constant2- 2- with rotational speed N held constantwith rotational speed N held constant

QQ = Capacity, Cubic Meter Per Second = Capacity, Cubic Meter Per Second HH = Total Head, Meter = Total Head, Meter BHPBHP = Brake Horsepower = Brake Horsepower NN = Pump Speed, RPM = Pump Speed, RPM

2

1

2

1

N

N

Q

Q

2

2

1

2

1

N

N

H

H

3

2

1

2

1

N

N

BHP

BHP

D is constant N is constant

3

2

1

2

1

D

D

Q

Q

2

2

1

2

1

D

D

H

H

5

2

1

2

1

D

D

BHP

BHP

Effect of Fluid ViscosityEffect of Fluid Viscosity

• The performance of centrifugal The performance of centrifugal pumps is affected when pumping pumps is affected when pumping viscous liquids.viscous liquids.

   

• A dramatic A dramatic increaseincrease in in Brake Brake HorsepowerHorsepower and A and A reductionreduction of of FlowFlow , , HeadHead andand pump efficiencypump efficiency occurs.occurs.

Centrifugal Centrifugal PumpPump Construction Construction

• ClassificationClassification• CasingsCasings• Radial ThrustRadial Thrust• ImpellersImpellers• Impeller Mechanical TypesImpeller Mechanical Types• Wearing RingsWearing Rings• Axial ThrustAxial Thrust• Axial Thrust in Multi-Stage PumpsAxial Thrust in Multi-Stage Pumps• Shafts and Shaft SleevesShafts and Shaft Sleeves• Mechanical SealsMechanical Seals

ImpellersImpellers

Mech . Power Mech . Power Hyd. Power ( H Hyd. Power ( Himpimp && VV22/2g )/2g )

ImpellersImpellers are are classifiedclassified according toaccording to the major the major direction of flowdirection of flow

Centrifugal pumps may have:Centrifugal pumps may have:

• RadialRadial-flow impellers-flow impellers

• AxialAxial-flow impellers-flow impellers

• MixedMixed-flow impellers, which combine -flow impellers, which combine radial- and axial-flow principlesradial- and axial-flow principles

radial single-suction closed impeller

radial double-suction closed impeller

Open mixed-flow impeller Axial-Flow impeller

• ImpellersImpellers are further are further classified as:classified as:

• Single-suctionSingle-suction,, with a single inlet on one side with a single inlet on one side• Double-suctionDouble-suction,, with water flowing to the with water flowing to the

impeller from both sidesimpeller from both sides

• The The mechanical constructionmechanical construction of the of the impellersimpellers gives a gives a subdivisionsubdivision intointo::

1. 1. EnclosedEnclosed,, with shrouds or side walls with shrouds or side walls enclosing enclosing the waterways the waterways

2. 2. OpenOpen, with no shrouds, with no shrouds3. 3. Semi-openSemi-open or semi-enclosed or semi-enclosed

radial double-suction closed impeller.

• The hydraulic The hydraulic characteristics of an inducercharacteristics of an inducer are are such that it requires considerably such that it requires considerably less NPSH less NPSH than a conventional impellerthan a conventional impeller. .

• An An inducerinducer is a is a low-headlow-head axial-flow impelleraxial-flow impeller with few blades which is with few blades which is placed placed in front of a in front of a

conventional impellerconventional impeller..

Variation in impeller profiles with specific speed

CASINGSCASINGS

UU22/2g /2g Hyd. Power ( H Hyd. Power ( Hcasingcasing && V Vdd22/2g )/2g )

• TheThe VoluteVolute CasingCasing PumpPump

• This pump derives its name from the This pump derives its name from the spiral-shapedspiral-shaped casing casing surrounding surrounding the impellerthe impeller. .

• This casing section This casing section collectscollects the liquid discharged by the impeller and the liquid discharged by the impeller and converts converts velocity energy to pressure energyvelocity energy to pressure energy..

• A centrifugal pump volute A centrifugal pump volute increases in areaincreases in area from its initial point until it from its initial point until it encompasses the full 360 around the impeller and then flares out to the encompasses the full 360 around the impeller and then flares out to the final discharge opening. final discharge opening.

• In In propeller and other pumpspropeller and other pumps in which axial-flow impellers are used, it is in which axial-flow impellers are used, it is not practical to use a volute casingnot practical to use a volute casing; instead, the impeller is enclosed ; instead, the impeller is enclosed in a pipe-like casing. in a pipe-like casing.

• A pump in which the head is A pump in which the head is developed by a developed by a single impellersingle impeller is is called a called a single-stagesingle-stage pumppump..

• Often the total Often the total headhead to be developed to be developed requiresrequires the use of the use of two or more two or more impellersimpellers operating in seriesoperating in series,or ,or multi-stagemulti-stage, , each taking its suction each taking its suction from the discharge of the preceding from the discharge of the preceding impeller.impeller.

Horizontal Multi-stage pump

Submersible Submersible pumps multi-pumps multi-

stagestage

Radial ThrustRadial Thrust

Arrangement of multi-stage volute pump for radial-thrust balance

AXIAL THRUSTAXIAL THRUST

AxialAxial ThrustThrust inin Single-StageSingle-Stage PumpsPumps withwith ClosedClosed ImpellersImpellers

• The The pressurespressures generated by a centrifugal pump generated by a centrifugal pump

exert forcesexert forces on both on both stationary stationary and and rotatingrotating parts. parts.

• Axial hydraulic thrustAxial hydraulic thrust on an impeller is on an impeller is the sum the sum of the unbalanced forces acting in the axialof the unbalanced forces acting in the axial directiondirection..

• As reliable large-capacity As reliable large-capacity thrust bearingsthrust bearings are now are now readily available, axial thrust in readily available, axial thrust in single-stage single-stage pumpspumps remains a problem only remains a problem only in larger unitsin larger units. .

Pressure distribution on: Front and Back shrouds of single-suction impeller

With shaft through impeller eye

• TheoreticallyTheoretically, a , a double-suction impellerdouble-suction impeller is in hydraulic is in hydraulic axial balanceaxial balance, with the pressures on one side equal to and , with the pressures on one side equal to and counterbalancing the pressures on the other.counterbalancing the pressures on the other.

BalancingBalancing axial thrustaxial thrust of of single-suction impellersingle-suction impeller by means of by means of wearing ringwearing ring on back sideon back side and and

balancing holesbalancing holes

Pump-out vanesPump-out vanes used in a used in a single-suction single-suction

impellerimpeller to to reduce axial thrustreduce axial thrust

Multistage pump with single-suction impellers Multistage pump with single-suction impellers facing in one direction and hydraulic facing in one direction and hydraulic balancingbalancing

devicedevice

Multi-stage pumpMulti-stage pump with back to back with back to back impellers.impellers.

Balancing drumBalancing drum

Simple balancing diskSimple balancing disk

CombinationCombination balancing balancing disk disk and and drumdrum

Specific applicationsSpecific applications

radial-vane non-clogging impeller used for solid handling

Paper pulp impeller

Open impellers

Open impeller with partial shroud

Semi-open impeller

WEARINGWEARING RINGSRINGS

• Wearing rings provide an easily and Wearing rings provide an easily and economically economically renewable leakage renewable leakage jointjoint between the between the impellerimpeller and the and the casingcasing. .

Plain flat leakage joint with no rings.

Single flat-casing-ring construction

Double flat-ring construction

Step-type leakage joint with double rings

An L-type nozzle casing ring.

Double rings, both of L type.

Single labyrinth inter-meshing type. Double-ring const. with nozzle-type casing ring

Labyrinth-type rings in double-ring construction

Wearing-ring clearances for single-stage pumps

ShaftShaft SleevesSleeves

• Pump shaftsPump shafts are usually are usually protected byprotected by renewable renewable sleeves fromsleeves from::

• EerosionEerosion, , corrosioncorrosion,, and and wearwear at at stuffing boxesstuffing boxes • Leakage joints Leakage joints • Internal bearingsInternal bearings

• In the In the waterwayswaterways

Sleeve with internal impeller nut, external shaft-sleeve nut, And separate key for sleeve

Sleeve with External locknut And Impeller key extending into

sleeve to prevent slip

Seal arrangement for shaft sleeveto prevent leakage along the shaft

Sealing Liquid ArrangementsSealing Liquid Arrangements

Water seal unit

Lantern RingLantern Ring

Lantern ring (also called seal Lantern ring (also called seal

cage)cage)

Weighted grease sealer. (Worthington Pump)

automatic grease sealer mounted on a vertical sewage pump

MECHANICAL SEALSMECHANICAL SEALS • The The conventional stuffing boxconventional stuffing box design and design and

composition composition packingpacking are are impracticalimpractical to use for to use for sealing a rotating shaft for many conditions of sealing a rotating shaft for many conditions of service.service.

• In the In the ordinary stuffing boxordinary stuffing box, the , the sealingsealing

between the moving shaft or shaft sleeve and the between the moving shaft or shaft sleeve and the stationary portion of the box is stationary portion of the box is accomplished byaccomplished by means of means of rings of packingrings of packing forced between the forced between the two surfaces and held tightly in place by a stuffing two surfaces and held tightly in place by a stuffing box box glandgland..

• The The leakageleakage around the shaft is around the shaft is controlledcontrolled

merely merely byby tighteningtightening up or up or looseningloosening the the gland studsgland studs. .

• The actual The actual sealing surfacessealing surfaces consist ofconsist of the the axial rotating surfacesaxial rotating surfaces of the shaft or shaft of the shaft or shaft sleeve and the sleeve and the stationary packingstationary packing. .

• Attempts to Attempts to reducereduce or or eliminateeliminate all all leakageleakage from a conventional stuffing box from a conventional stuffing box increase the increase the gland pressuregland pressure. .

• The The packingpacking,, being semi-plastic, forms being semi-plastic, forms more more closely to the shaftclosely to the shaft and tends to cut down the and tends to cut down the leakage. leakage.

• After a certain pointAfter a certain point, however, , however, the leakagethe leakage continuescontinues no matter how tightly the gland studs no matter how tightly the gland studs are brought up. are brought up.

• The The frictional horsepowerfrictional horsepower increases increases rapidlyrapidly at this point, the heat generated at this point, the heat generated cannot be properly dissipated, and the cannot be properly dissipated, and the stuffing box fails to function.stuffing box fails to function.

• Even before this condition is reached, the Even before this condition is reached, the shaft sleevesshaft sleeves may be may be severely worn and severely worn and scoredscored, so that it becomes , so that it becomes impossibleimpossible to to pack the stuffing box satisfactorily.pack the stuffing box satisfactorily.

• These These undesirable characteristicsundesirable characteristics ofof using using packingpacking as the sealing medium as the sealing medium between rotating surfaces if the leakage is between rotating surfaces if the leakage is to be held to an absolute minimum under to be held to an absolute minimum under severe pressure severe pressure

• The condition, in turn, automatically The condition, in turn, automatically eliminates use ofeliminates use of the the axial surfacesaxial surfaces as as the sealing surfaces, for a non-plastic the sealing surfaces, for a non-plastic packing is the only material that can always packing is the only material that can always be made to form about the shaft and be made to form about the shaft and compensate for the wear.compensate for the wear.

• Another factor that makes Another factor that makes stuffing boxesstuffing boxes unsatisfactoryunsatisfactory for certain applications is for certain applications is the relatively the relatively small lubricating valuesmall lubricating value of of many liquids frequently handled by many liquids frequently handled by centrifugal pumps, such as centrifugal pumps, such as propanepropane or or butanebutane. .

• These liquidsThese liquids actually actually dissolve the dissolve the lubricantslubricants normally used to impregnate normally used to impregnate the packing. the packing.

• Seal oilSeal oil must therefore be must therefore be introduced introduced intointo the the lantern glandlantern gland or a or a packed boxpacked box to lubricateto lubricate the packing and give it the packing and give it reasonable life. reasonable life.

• With these facts in mind, designers have With these facts in mind, designers have attempted to produce an entirely different attempted to produce an entirely different type of seal type of seal with wearing surfaceswith wearing surfaces other other than the axial surfacesthan the axial surfaces of the shaft and of the shaft and packing.packing.

• The The mechanical sealmechanical seal, is a , is a later later developmentdevelopment than regular than regular stuffing boxesstuffing boxes but has found general acceptance in those but has found general acceptance in those pumping applications in which the pumping applications in which the shortcomings of packed stuffing boxes have shortcomings of packed stuffing boxes have proved excessive. proved excessive.

• Fields in which the Fields in which the packed boxespacked boxes gave gave good good serviceservice, however, have shown , however, have shown little little tendency to replace themtendency to replace them with mechanical with mechanical seals.seals.

• The The most commonmost common method of sealing method of sealing centrifugal pumps today uses the centrifugal pumps today uses the mechanical sealmechanical seal ( (Fig.Fig.). ).

• The three basic parts of a mechanical seal are as The three basic parts of a mechanical seal are as follows:follows:

• PrimaryPrimary sealseal components:components: These consist of an These consist of an axially adjustableaxially adjustable sealing sealing

ringring and an axially fixed and an axially fixed mating ringmating ring against against which it slides, forming a seal. which it slides, forming a seal. Depending on Depending on the seal configurationthe seal configuration, either the , either the sealingsealing or or the the matingmating ring may be the ring may be the rotating rotating or or stationarystationary element. element.

• SecondarySecondary seals:seals: These consist of These consist of O-ringsO-rings or other suitable or other suitable gasket materialsgasket materials..

• HardwareHardware:: This consists mainly of the This consists mainly of the spring(s)spring(s) and a and a retainerretainer, normally made of a series 300 stainless , normally made of a series 300 stainless steel.steel.

Basic components of a mechanical Basic components of a mechanical

sealseal....

Comparison of packing and mechanical seals

Advantages Disadvantages

Packing

1. Lower initial cost2. Easily installed as rings and glands are split3. Good reliability to medium pressures and shaft speeds4. Can handle large axial movements (thermal expansion of stuffing box versus shaft)5. Can be used in rotating or reciprocating applications 6. Leakage tends to increase gradually, giving warning of impending breakdown

1. Relatively high leakage 2. Requires regular maintenance 3. Wear of shaft and shaft sleeve can be relatively high4. Power losses may be high

Advantages Disadvantages

Mechanical seals1. Very low leakage/no leakage 2. Require no maintenance 3. Eliminate sleeve wear/shaft wear 4. Very good reliability 5. Can handle higher pressures and speeds 6. Easily applied to, toxic, flammable, or radioactive liquids 7. Low power loss

1. Higher initial cost

2. Easily installed but may require some disassembly of pump

(couplings and so on)

Single Acting Piston PumpSingle Acting Piston Pump

Double Acting Piston pumpDouble Acting Piston pump

Diaphragm PumpDiaphragm Pump

Air Operated Diaphragm Air Operated Diaphragm PumpPump

External Gear PumpExternal Gear Pump

External Gear PumpExternal Gear Pump

External Gear PumpExternal Gear Pump

External Gear PumpExternal Gear Pump

Internal Gear PumpInternal Gear Pump

External Gear PumpExternal Gear Pump

Screw PumpScrew Pump

Radial Piston pumpRadial Piston pump

Vane PumpVane Pump

Parallel Cylinder Piston Parallel Cylinder Piston PumpPump

Swash Plate PumpSwash Plate Pump

Finger PumpFinger Pump

Peristaltic Peristaltic PumpPump

Jet PumpJet Pump

In your car there are three In your car there are three types of pumps:types of pumps:

1.1. Water pump for cooling. Water pump for cooling.

2.2. Oil pump for lubrication. Oil pump for lubrication.

3.3. Fuel pump for engine combustion. Fuel pump for engine combustion.

a-a- What are these types?What are these types?

b-b- Compare these types according Compare these types according to to function of each .function of each .

Pumping StationsPumping Stations

Pumping StationsPumping Stations

Pumping StationsPumping Stations

Sewage Pumping StationSewage Pumping Station

Water Treatment PlantsWater Treatment Plants

Water Treatment PlantsWater Treatment Plants

Wastewater Treatment Wastewater Treatment PlantsPlants

Fire Fighting Fire Fighting systemssystems

Hydraulic TurbinesHydraulic Turbines

DefinitionDefinition

Turbine is a Turbine is a hydraulic hydraulic machine machine used to used to convert convert hydraulichydraulic powerpower into into mechanical mechanical powerpower

I/P O/PI/P O/P( Hyd. Energy ) ( Mech. Energy )( Hyd. Energy ) ( Mech. Energy )T

DamsDams and and ReservoirsReservoirs

A picture for A hydro-power plant

Water TurbinesWater Turbines

Spiral casing

Draft tube

Runner

Francis TurbineFrancis Turbine

Types of Hydraulic Turbine Types of Hydraulic Turbine RunnersRunners

AerodynamicsAerodynamics

AutomotivesAutomotives

Wind TunnelsWind Tunnels

Sports machines require the understanding of Sports machines require the understanding of F.M.F.M.

Water sports

Auto racing

Offshore racingCycling

Surfing

Airplanes & RocketsAirplanes & Rockets

Wind EnergyWind Energy

THANK YOUTHANK YOU