PumpTech Customer Education - PNWS- Sessions... · PDF file Bernoulli’s theorem...

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Transcript of PumpTech Customer Education - PNWS- Sessions... · PDF file Bernoulli’s theorem...

  • PumpTech Customer Education

    Bellevue Moses Lake Canby

    http://www.Pumptechnw.com

    Joe Evans, Ph.D

  • Pump Ed 101

    Centrifugal Pump Hydraulics

    Three Reasons BEP Operation is Important

    Joe Evans, Ph.D

    http://www.PumpEd101.com

    Pump ED 101

  • Centrifugal Pumps

    Animated Software Company

    Pump ED 101

    *

    Displacement

  • Impellers

    Pump ED 101 Dynamics

    *

  • Centrifugal Pump Dynamics

    Discharge

    Volute

    Impeller

    Suction

    What Type of Energy is Added by the Impeller ?

    Pump ED 101

    Hint *

    Dynamics

    Centrifugal

    Cutwater

    MSAWWA08/bugOnADisk.swf

  • Centrifugal Force

     It is defined as “center fleeing”

    Pump ED 101 Dynamics

    *

    ../../PP Presentations/PP's under construction/Centrifugal training/car.html

  • Centrifugal Force

     When an object is traveling in a circle, it is actually moving in a straight line at any single point in time.

     Instead it actually moves in the same direction it was traveling at the exact instant it is released.

    Farce

    Pump ED 101

    *

    Dynamics

    cforce.gif

  • So, How Does It Work ?

    1 Rotation of the impeller forces water from its entry point, at the eye, into its vanes.

    2 Water moving through the vanes creates a partial vacuum at the eye allowing atmospheric, or some other outside pressure, to force more water into the eye.

    3 As water travels through the vanes, it gains rotational velocity (kinetic energy) and reaches its maximum velocity just as it exits the vanes.

    4 Upon exiting the vanes, water enters the volute where most of its kinetic energy of motion is transformed into pressure energy.

    Pump ED 101

    *

    Dynamics

  • The Volute and its Function

    The volute houses the impeller and is the “receptacle” for the water exiting its vanes.

    Its smooth, nearly circular, geometry guides the flow from the impeller towards its discharge. During this trip, the flow encounters an ever increasing volume.

    The volute converts the kinetic energy (velocity) imparted by the impeller into pressure.

    Pump ED 101

    *

    Dynamics

  • The Performance Curve

     Pump Information

     Flow and Pressure at Several Points

     Hydraulic Efficiency

     Horsepower

     Net Positive Suction Head Required (NPSHr)

    Pump ED 101

    *

    Curve

  • Pump ED 101

    The Performance Curve

  • Pump ED 101

    The Performance Curve

    BEP

    11.5”

  • Pump ED 101

    The Performance Curve

    BEBOP

  • The Performance Curve

    Pump ED 101

    *

    Curve

    BEBOP

  • BEBOP & The Cost of Pump Operation

     Power consumption is at its lowest

     Maintenance costs are their lowest

     Useful life is at its maximum

    Pump ED 101

    When a centrifugal pump is operated at BEBOP

    ../../../../Program Files/America Online 7.0/pumped101.com files/series parallel.xls ../../PP Presentations/PP's under construction/Centrifugal training/series parallel.xls

  • 0

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    0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700

    H e a d (

    ft )

    Gallons Per Minute

    System Curve Design Flow

    300' 6" Steel Pipe

    Pump ED 101

    The System Curve

  • 121

    105

    95

    87

    79

    72

    65

    57

    49

    121

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    95

    87

    79

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    65

    57

    49

    0

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    0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700

    H e a d (

    ft )

    Gallons Per Minute

    Simplex Duplex

    System Curve Design Flow

    H4HX 1750 RPM, Trim 10", 71% eff

    300' 6" Steel Pipe

    Pump ED 101

    The System Curve

    13.8 HP

    24.4 HP

  • 109

    93

    83

    74

    66

    60

    52

    45

    37

    109

    93

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    66

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    45

    37

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    0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700

    H e

    a d

    ( ft

    )

    Gallons Per Minute

    Simplex Duplex System Curve Design Flow

    H4HX 1750 RPM, Trim 9.5", 71% eff

    300' 8" Steel Pipe

    Pump ED 101

    The System Curve

    11.5 HP

    22.2 HP

    ../../../../../../Program Files/Hydromatic Pumps/H2Optimize Hydromatic/h2opt.exe

  • System Hydraulics – Radial Thrust

     Ideally a pump should operate between 90% and 110% of its BEBOP.

     If it does not, the radial forces that act upon a centrifugal pump’s impeller can account for a large percentage of premature failures.

     The increased shaft deflection will decrease mechanical seal, wear ring, and bearing life.

     Worse case - shaft breakage

    19 Pump Ed 101

  • • Forms about the periphery of the impeller due to uneven volute geometry

    • A function of total head, width and diameter of the impeller

    • Usually reaches a maximum at or near shut off head

    Radial Thrust

    Pump Ed 101

    MSAWWA08/bugOnADisk.swf

  • Pump ED 101

    Radial Thrust Factor

    ../../../../Program Files/America Online 7.0/pumped101.com files/series parallel.xls

  • Pump ED 101

    Radial Thrust Calculator

    ../../../../Program Files/America Online 7.0/pumped101.com files/series parallel.xls radial thrust calculator.xls

  • Pump ED 101

    Cavitation

    ../../../../../Program Files/America Online 7.0/pumped101.com files/series parallel.xls

  • Pump ED 101

    Types of Cavitation

    Normal Cavitation – Low NPSHa

    Wear Ring Recirculation – Low Flow

    Discharge Recirculation – Low Flow

    Suction Recirculation – Low Flow

    ../../../../../Program Files/America Online 7.0/pumped101.com files/series parallel.xls

  • Pump ED 101

    Types of Cavitation

    ../../../../../Program Files/America Online 7.0/pumped101.com files/series parallel.xls

  • Pump ED 101

    Wear Ring Recirculation

    Cavitation

    ../../../../../Program Files/America Online 7.0/pumped101.com files/series parallel.xls

  • Pump ED 101

    Discharge Recirculation Cavitation

    Occurs on the high pressure side of the vane

    ../../../../../Program Files/America Online 7.0/pumped101.com files/series parallel.xls

  • Pump ED 101

    Discharge Recirculation Cavitation Two Vane

    ../../../../../Program Files/America Online 7.0/pumped101.com files/series parallel.xls

  • Pump ED 101

    Suction Recirculation Cavitation

    Occurs on the high pressure side of the vane

    ../../../../../Program Files/America Online 7.0/pumped101.com files/series parallel.xls

  • Pump ED 101

    Suction Recirculation Cavitation

    ../../../../../Program Files/America Online 7.0/pumped101.com files/series parallel.xls

  • Pump ED 101

    Suction & Discharge Recirculation Cavitation

    ../../../../../Program Files/America Online 7.0/pumped101.com files/series parallel.xls

  • Conservation of Energy

    50 PSI 50 PSI 48 PSI

    100 GPM

    Pump ED 101

    Bernoulli’s theorem states that, during steady flow, the energy at any point in a conduit is the sum of the velocity head, pressure head, and elevation head. It also states that this sum will remain constant if there are no losses. Daniel Bernoulli 1700-1782

    H = v + p + z = Constant

    *

    Dynamics

    ../../../../Administrator/Desktop/test/test.html

  • Pump ED 101 Total Head

    Total Suction Head hs = ± hgs + hvs ± Zs

    Total Discharge Head hd = hgd + hvd ± Zd

    Total Dynamic Head H = hd - hs

    Total Dynamic Head

    Where:

    hg = gauge head

    hv = velocity head

    Z = gauge distance above or below datum

    Where:

    hd = discharge head

    hs = suction head

    ../../../../Program Files/America Online 7.0/pumped101.com files/series parallel.xls Field Test.xlsx

  • Pump ED 101

    *

    Dynamics

    What is Velocity Head ?

    It is a form of energy that cannot be measured with a pressure gauge.

    Why is It Important ?

    If it is not measured, pump test r