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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
24Efficiency
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.