Know and Understand Centrifugal Pumps

Edited by

  • L. Bachus, Bachus Company Inc
  • A Custodio

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.
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Mechanical engineers, fitters and maintenance engineers.


Book information

  • Published: July 2003
  • Imprint: ELSEVIER
  • ISBN: 978-1-85617-409-1

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