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Fundamentals of PumpsJohan MeintjesGreenstone, 14 March 2013

2Introduction to PumpingConstruction of Centrifugal PumpsPump FundamentalsPump CharacteristicsPump and System curvesPump SelectionFundamentals of Pumps

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Why are pumps important?

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IntroductionNounA mechanical device using suction or pressure to raise or move liquids or gases

2.A light shoe, in particular.VerbForce to move a substance (liquid, gas, etc.) in a specified direction : "the blood is pumped around the body".

4pump/pmp/

Introduction5pumping/pmpiNG/

IntroductionPumps are divided into &6Roto-dynamic or Centrifugal pumpsPositive displacement pumps

70%30%

Construction of a Centrifugal Pump

Wet endBearing unitCouplingSuctionDischargeImpellerElectric MotorVoluteStuffing boxShaft

Construction of a Centrifugal Pump8

Construction of a Centrifugal PumpImpeller Types9

OpenSolids handling, low flow, entrained gases, reduced efficienciesSemi-Openmoderately abrasive slurries, if blocking is a concern ClosedHigh heads, high flow, improved efficiencies

Pump FundamentalsA pump adds energy (pressure) to a fluidPressure in pump casing causes flowhigh pressure @ low flow or high flow @ low pressure(and everything in between )

Operating pointReliability and energy use are highly dependent on the operating point10

Pump Fundamentals11

Adding energy - Impeller

Pump Fundamentals12Pressure = Force per unit areaHead VS. Pressure

Area = 1 in2Pressure (psig) = 20 psi (137.9 kPa)

Pump Fundamentals13Headis the linear vertical measurement of the height a specific pump can deliver a liquid

Area = 1 in2Pressure (psig) = 20 psiHead VS. Pressure

SG= 1 (Water)46.2 ft.14.1mh = 2.31 x ppsi / SGh = 0.0981 x pbar / SG

Pump Fundamentals14

A (m2)VQ

Pump Fundamentals15Effect of Specific Gravity on pump performance

30 m15 kW3.4 barSulfuric acidSG = 1.8

30 m7.5 kW3 barWaterSG = 1

30 m5.5 kW2.2 barPetrolSG = 0.75

Pump Characteristics16

System Characteristics17It takes Energy to lift fluid from one level to anotherThe pressure energy (head) that has to be overcome to lift a fluid is called static head

System Characteristics18

System Characteristics19

System CharacteristicsThe Moody diagram20

System CharacteristicsSources of FrictionPipe walls (Roughness)ValvesElbowsTeesReducers/expandersExpansion jointsTank inlets/outlets21

System Characteristics22

Static headFriction headDischarge headTotal Dynamic Head

Pump CharacteristicsPump Curve23

HeadFlow Rate

Pump curveSystem curveDuty/Operating point

Pump CharacteristicsLosses lowest / efficiency highest, at the Best Efficiency Point (BEP)The ratio between output power and input power is the efficiency of the pumpLosses can be measured by comparing delivered hydraulic power to input power

= Output / Input

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Pump Characteristics

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Pump CharacteristicsNPSH and CavitationNPSH is a measure of the energy (pressure) on the suction of the pumpIf the pressure drops below the vapour pressure, the liquid boils!26

Pump CharacteristicsCavitationThe pressure of the fluid drops below the vapour pressure, the liquid boils and tiny bubbles form!

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Pump Characteristics28

Bubble Collapses creating intense pressure (10,000 psi) and shock waves Intense pressures on metal surfaces exceed material strength resulting in surface fatigue failureCreates a pitted surface similar to coral or course sandpaper

Pump Characteristics29

System Characteristics30Power Required

Pump Selection Software31

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QUESTIONS Thank You

32Il sottotilo pu essere inserito, altrimenti lasciarlo vuoto.