Know and Understand Centrifugal Pumps

Know and Understand Centrifugal Pumps

1st Edition - July 25, 2003

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  • Editors: L. Bachus, A Custodio
  • eBook ISBN: 9780080509747
  • Hardcover ISBN: 9781856174091

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Pumps are commonly encountered in industry and are essential to the smooth running of many industrial complexes. Mechanical engineers entering industry often have little practical experience of pumps and their problems, and need to build up an understanding of the design, operation and appropriate use of pumps, plus how to diagnose faults and put them right. This book tackles all these aspects in a readable manner, drawing on the authors' long experience of lecturing and writing on centrifugal pumps for industrial audiences.


Mechanical engineers, fitters and maintenance engineers.

Table of Contents

  • Chapter 1: Basic Pump Principles


    How do pumps work?

    Pressure measurement

    Atmospheric pressure (ATM)

    Absolute pressure (psia)

    Gauge pressure (psig)


    Pump head

    Specific gravity

    Pressure measurement

    Pressures inside the pump

    Chapter 2: NPSH, Net Positive Suction Head


    Definition of NPSHr (required)

    Definition NPSHa (available)

    Chapter 3: Cavitation


    Vapor pressure


    The effects of vapor pressure on pump performance

    Cavitation: A practical discussion

    Review for preventing cavitation

    Cavitation review

    Do something about cavitation!

    Chapter 4: The Affinity Laws


    The Laws

    The Affinity Laws and the impeller diameter

    What's the practical application of these laws?

    Chapter 5: Useful Work and Pump Efficiency

    Useful work from a pump

    Flow determination

    Pump efficiency

    Factors that affect the efficiency

    Calculating pump efficiency

    Chapter 6: Pump Classification


    Positive displacement pumps

    Centrifugal pumps

    Conceptual difference

    Centrifugal volate pumps

    Types of centrifugal pumps

    Overhung impeller

    Impeller between the bearings

    Turbine pumps

    Specific duty pumps

    The typical ANSI pump

    API (American Petroleum Institute) pumps

    Vertical turbine pumps

    Non-metalic pumps

    Magnetic drive pumps

    Canned motor pumps

    Pump impellers

    Turbine impellers

    Conventional impellers

    Suction specific speed, Nss

    Open impellers

    Semi open impeller

    Totally enclosed impeller

    Wer bands

    Specific speed, Ns

    Chapter 7: Understanding Pump Curves

    Pump performance curves


    Head versus pressure


    Pump efficiency

    The energy (BHp) curve

    The pump's minimum requirements (NPSH)

    Special design pumps

    Family curves

    Chapter 8: The System Curve

    The system controls the pump

    The elements of the Total Dynamic Head (TDH)

    Determining the Hs

    Determining the Hp

    Calculating the Hf and Hv

    The dynamic system

    Variable elevations

    The happy zone

    Dynamic pressures

    Variable resistances

    Short term reistance changes

    Long term reistance changes

    Pumps in parallel and pumps in series

    Pumps in parallel

    Three tips

    Pumps running in series

    Combined parallel and seris pump operation

    Chapter 9: Shaft Deflection


    Operation, design and maintenance

    Signs of shaft deflection

    Interpreting the evidence

    The sweet zone

    The dual volute pump

    Chapter 10: Pump and Motor Alignment


    Types of misalignment

    Alignment techniques

    Equipment alignment sequence

    Coupling alignment

    Chapter 11: Bearings


    Bearing lubrication

    Bearing failure

    Bearing maintenance

    Bearing seals

    Chapter 12: Pump Shaft Packing


    Vegetable fibers

    Reciprocating action


    Rotary action

    Synthetic fibers

    Compression packing

    The lantern ring

    The packing lubricant

    Stages in the life of packing

    Chapter 13: Mechanical Seals

    Pump packing


    The mechanical seal

    The single, unbalance, insider mounted mechanical seal

    The single, outside-mounted, unbalanced seal

    The single, balanced, internal mechanical seal

    The single, balanced, external mechanical seal

    Advantages of o-rings

    The balance effect

    Advantages of balance

    Balance explained by math

    Cartridge mechanical seals

    Double seals

    The tandem dual seal

    The back-to-back double seal

    The fact-to-face dual seal

    Support systems for dual seals

    The thermal convection tank

    The turbo tank

    The pumping unit

    Chapter 14: Failure Analysis of Mechanical Seals

    Causes of premature seal failure

    O-ring (the elastomer) failure

    The elastomer sticks to the shaft

    The springs clog and jam

    The shaft frets under the shaft seal

    Incorrect installation dimension

    Environmental controls for difficult sealing applications

    Difficult pumping applications for mechanical seals

    Environmental control

    Proper pump repair alignment methods

    Chapter 15: Common Sense Failure Analysis

    Pump maintenance files

    Failure analysis on centrifugal pumps

    Why is this pump in the shop?

    Chapter 16: Avoiding Wear in Centrifugal Pumps




    Wear rings

    Fluid velocity accelerates wear



    Chapter 17: Pump Piping


    Piping design to drain tanks and sumps

    The Submergence Laws

Product details

  • No. of pages: 264
  • Language: English
  • Copyright: © Elsevier Science 2003
  • Published: July 25, 2003
  • Imprint: Elsevier Science
  • eBook ISBN: 9780080509747
  • Hardcover ISBN: 9781856174091

About the Editors

L. Bachus

Affiliations and Expertise

Bachus Company Inc

A Custodio

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