Page 12 - Know and Understand Centrifugal Pumps

Contents

The face-to-face dual seal 197
Support systems for dual seals 198
The thermal convection tank 198
The turbo tank 199
The pumping unit 200

14 Failure Analysis of Mechanical Seals 202
Causes of premature seal failure 202
O-ring (the elastomer) failure 204
The elastomer sticks to the shaft 209
The springs clog and jam 210
The shaft frets under the shaft seal 21 1
Incorrect installation dimension 212
Environmental controls for difficult sealing applications 213
Difficult pumping applications for mechanical seals 2 14
Environmental controls 215
Proper pump repair alignment methods 222

15 Common Sense Failure Analysis 226
Pump maintenance files 226
Failure analysis on centrifugal pumps 227
Why is this pump in the shop? 228

16 Avoiding Wear in Centrifugal Pumps 232
Introduction 232
Erosion 232
Corrosion 233
Wear rings 233
Fluid velocity accelerates wear 235
Turbulence 235
Throttling 236

17 Pump Piping 238
Introduction 238
Piping design to drain tanks and sumps 238
The Submergence Laws 243

Index 248

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