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Contents

2.2.3.2 Pump run-out 22
2.2.3.3 Minimum flow point 22
2.3 Affinity laws 23
2.3.1 Change of electric motor for performance
change 25
2.3.2 Other changes 25
2.4 Pump performance on special liquids 26
2.5 Impeller hydraulic loads 27
2.5.1 Radial thrust 28
2.5.2 Shaft deflection 29

System Hydraulics 31
3.1 Pump limitations 31
3.2 Liquid flow in pipes 31
3.2.1 Specific gravity 31
3.2.2 Pressure in a static system 32
3.2.3 Pressure in a flowing system 32
3.2.4 Changes in an existing system 33
3.2.4.1 The effect of capacity change
on friction 33
3.2.4.2 The effect of head change on
flow rate 34
3.2.5 Pipe size changes in a system 34
3.3 Basic elements of pump system design 35
3.3.1 Gravity and static head 35
3.3.2 Friction losses and friction head 36
3.3.3 Velocity head 37
3.3.4 Total head 37
3.4 System curve 37
3.5 The effect of operating performance 38
3.5.1 Static head changes 38
3.5.1.1 Batch transfer system 38
3.5.1.2 Pressurized system 39
3.5.1.3 Closed loop system 40
3.5.2 Friction head changes 40
3.5.2.1 System controls 40
3.5.2.2 Restrictions in piping 40
3.5.3 Recirculation systems 40
3.5.4 Pump speed changes 41
3.5.5 Series and parallel operation 42
3.5.5.1 Series operation 42
3.5.5.2 Parallel operation 43

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