The use of submersible pumps in sewage and
drainage pumping applications has increased
greatly in the last decades since they entered the
market. The introduction of heavy-duty submersible
pumps with motor power ratings exceeding
500 kW has also made them available for central
municipal pumping duties. The good service
record and high quality standard attained by
these pumps has all but excluded the use of conventional
pumps in municipal service.
Table of Contents
1 Pump Theory ............................................. 7
1.1 The Head Equation .........................................7
1.1.1 Flow with Losses or Addition of Energy ....7
1.1.2 Fluid Flowing from a Container .................. 8
1.2 The Basic Pump Equation ............................. 8
1.3 Pump Curve and Losses ...............................10
1.3.1 The Effect of Finite Number of Vanes ......10
1.3.2 Friction Losses Hf ..........................................10
1.3.3 Discontinuity Losses Hs ...............................10
1.3.4 Leakage Losses Hv .........................................10
1.3.5 Other Losses ....................................................11
1.4. Cavitation and NPSH .....................................11
1.4.1 Definition of NPSH .......................................12
1.4.2 Reference Plane .............................................12
1.4.3 Required NPSH ...............................................12
1.4.4 Available NPSH ..............................................14
1.4.5 NPSH Safety Margin ..................................... 15
1.4.6 Damming up of Suction Wells................... 15
2 Pump Construction ................................. 16
2.1 General ............................................................16
2.2 Pump ................................................................18
2.2.1 Impellers ..........................................................18
2.3 Motors ............................................................. 27
2.3.1 General ........................................................... 27
2.3.2 Explosion-proof Motors .............................. 27
2.3.3 Motor Cooling ............................................... 27
2.3.4 Motor Tightness ...........................................29
2.3.5 Motor Bearings ..............................................31
2.3.6 Motor Protection Devices .......................... 32
2.4. Pump Connection ........................................ 34
2.5 Construction Materials,
Corrosion and Wear .....................................36
2.5.1 Corrosion Resistance ...................................36
2.5.2 Wear Resistance ........................................... 37
2.5.3 Abrasive Liquids ............................................ 37
3 Pump Performance ..................................38
3.1 Pump Head ....................................................38
3.1.1 Submersible Pumps .....................................38
3.1.2 Dry-installed Pumps ....................................39
3.2 Pump Performance Curves ........................39
3.2.1 H Curve ...........................................................39
3.2.2 Efficiency Curves ..........................................40
3.2.3 Power Curves .................................................40
3.2.4 NPSH Curve ....................................................40
3.3 Pipe Losses and Rising Main
Characteristic Curves ...................................41
3.3.1 Friction Losses ................................................41
3.3.2 Local Losses ....................................................43
3.3.3 Rising Main Characteristic Curve .............43
3.4 Rising Main Size ............................................44
3.4.1 Economy .........................................................44
3.4.2 Free Passage for Solids ................................45
3.4.3 Avoiding Settling of Solids and Sludge ...45
3.4.4. Water Hammer..............................................45
3.4.5 Avoiding Water Hammer ...........................47
3.5 Pump Duty Point ..........................................48
3.5.1 Single Pump Operation ...............................48
3.5.2 Parallel Operation, Identical Pumps ........48
3.5.3 Parallel Operation, Different Pumps ........48
3.5.4 Serial Operation ........................................... 49
3.5.5 True Duty Point ............................................ 49
3.6 Sludge Pumping ........................................... 49
3.7 Complex Rising Mains ................................ 49
3.7.1 What Goes on in a Complex
Rising Main? ................................................. 49
3.7.2 Determination of Head ................................51
3.7.3 Pipe Size and Flow Velocity .........................51
3.7.4 Choice of Pump ..............................................51
3.7.5 Confirming Measurements ........................51
3.8 Duty Point Evaluation for
Parallel Pumping Stations .......................... 52
4 Testing of Pumps .....................................54
4.1 Testing Arrangements .................................54
4.1.1 Production Testing .......................................54
4.1.2 Field Testing, Duty Point .............................56
4.2 Acceptance Tests .......................................... 57
4.2.1 Testing Standards ......................................... 57
5 Pumping Stations ....................................59
5.1 Pumping Station Basic Design ..................59
5.1.1 Wet Well Volume and Surface Area ........59
5.1.2 Pumping Station Inlet Pipe ....................... 60
5.1.3 Wet Well Floor Shape ................................. 60
5.1.4 Stop Levels ...................................................... 61
5.1.5 Start Levels .....................................................62
5.1.6 Suction Pipe Dimension and Design .......62
5.1.7 Pumping Station Internal Pipework ........63
5.1.8 Flushing Devices ...........................................63
5.1.9 Odour Problems in Pumping Stations .... 64
5.1.10 Pumping Station Design Examples ......... 64
5.1.11 Dry-installed Pump Positions ....................67
5.2 Package Pumping Stations ........................ 68
5.2.1 Out-of-doors Pumping Stations .............. 68
5.2.2 Indoor Pumping Stations ...........................70
5.3 Pumping Stations with
Column-installed Pumps ............................70
5.4 Pumping Station Dimension Selection ... 72
5.4.1 Regular Sewage Pumping Stations .......... 72
Table of Contents
6
5.4.2 Stormwater Pumping Stations ..................72
5.4.3 Combined Sewage Pumping Stations
and Retention Basins ...................................73
5.5 Pump Selection ..............................................74
5.5.1 Pump Selection Based on Pump Curves ..74
5.5.2 Observing Pump Efficiency .........................74
5.5.3 Number of Pumps .........................................75
5.6 Special Considerations ................................76
5.6.1 Pump Vibrations ............................................76
5.6.2 Pump Noise ....................................................77
6 Frequency-controlled Sewage Pumps ........... 78
6.1 General ........................................................... 78
6.1.1 Pump Motor Selection ................................ 78
6.1.2 Maximum Frequency .................................. 78
6.1.3 Minimum Frequency and Minimum
Performance.................................................. 79
6.1.4 Pump Frequency Curves ............................. 79
6.1.5 Pump Clogging .............................................80
6.1.6 EMC Cable Requirement ............................80
6.1.7 Bearing Currents ..........................................80
6.1.8 High Tension ..................................................81
6.1.9 Explosion-proof Motors ..............................81
6.1.10 Guaranteed Values .......................................81
6.1.11 Tests with Frequency Controller
(String Tests) ...................................................81
6.1.12 Collaboration with the Pump
Manufacturer .................................................81
7 Pump Whole-life Cost Evaluation .......... 82
7.1 General ........................................................... 82
7.2 Calculation Period ........................................ 82
7.3 Investment Costs ......................................... 82
7.4 Energy Costs .................................................. 83
7.4.1 Efficiency Over Time .................................... 83
7.4.2 Energy Usage Calculations ........................84
7.5 Maintenance Costs ......................................84
7.6 Cooperation With Pump Suppliers .......... 85
7.7 Life Cycle Cost Publication ......................... 85
8 Commissioning .......................................86
9 Operation and Service ............................ 87
9.1 Safety .............................................................. 87
10 Pumping Station Control and
Condition Monitoring ............................. 88
10.1 Local Control Methods ...............................88
10.1.1 Manual Control Units .................................88
10.1.2 Relay-based Control Units .........................88
10.1.3 Programmable Logic Controllers ..............88
10.2 Sensors for Pump Control and
Condition Monitoring .................................89
10.2.1 Wet Well Water Level Sensors ..................89
10.2.2 Current Sensor ............................................. 90
10.2.3 kWh Meter .................................................... 90
10.2.4 Phase Failure Relay ...................................... 90
10.2.5 SARI 2 Monitoring Device .......................... 90
10.2.6 ASM 3 Alarm Status Module ......................91
10.3 Pump Control Units ......................................91
10.3.1. Control Features ............................................91
10.3.2 Condition Monitoring Features ................92
10.3.3 Parameters and Signals ..............................92
10.3.4 Data Logging and Analysis .........................93
10.3.5 User Interface ................................................93
10.4 Remote Control and Monitoring System 93
10.4.1 Different Levels for Remote Control ........93
10.4.2 Software and Hardware .............................94
10.4.3 Data Transmission .......................................95
10.4.4 Alarm Transfer ...............................................95
10.4.5 System Integration ......................................96
10.5 Internet & WAP Based Remote Control
and Monitoring .............................................96
Symbols .............................................................98
APPENDIX A ...................................................... 100
APPENDIX B....................................................... 108
The Sewage pumping handbook