Brochure

4.4 Usage of Euler’s pump equation .................................... 67
4.5 Anity rules ...............................................................................68
4.5.1 Derivation of anity rules .............................. 70
4.6 Pre-rotation .................................................................................72
4.7 Slip ......................................................................................................73
4.8 The pump’s specific speed .................................................74
4.9 Summary .......................................................................................75
Chapter 5. Pump losses ............................................................ 77
5.1 Loss types ......................................................................................78
5.2 Mechanical losses ...................................................................80
5.2.1 Bearing loss and shaft seal loss ...................80
5.3 Hydraulic losses .......................................................................80
5.3.1 Flow friction................................................................81
5.3.2 Mixing loss at
cross-section expansion ............................86
5.3.3 Mixing loss at
cross-section reduction ......................................87
5.3.4 Recirculation loss ...................................................89
5.3.5 Incidence loss ...........................................................90
5.3.6 Disc friction ................................................................ 91
5.3.7 Leakage ......................................................................... 92
5.4 Loss distribution as function of
specific speed ............................................................................ 95
5.5 Summary ...................................................................................... 95
Chapter 6. Pumps tests ................................................ 97
6.1 Test types .....................................................................................98
6.2 Measuring pump performance .....................................99
6.2.1 Flow ...............................................................................100
6.2.2 Pressure ....................................................... 100
6.2.3 Temperature ........................................................... 101
6.2.4 Calculation of head ............................................ 102
6.2.5 General calculation of head ....................103
6.2.6 Power consumption ........................................... 104
6.2.7 Rotational speed .................................................. 104
6.3 Measurement of the pump’s NPSH ......................... 105
6.3.1 NPSH
3%
test by lowering the
inlet pressure .............................................. 106
6.3.2 NPSH
3%
test by increasing the flow .......... 107
6.3.3 Test beds .................................................................... 107
6.3.4 Water quality .......................................................... 108
6.3.5 Vapour pressure and density.......................108
6.3.6 Reference plane ....................................................108
6.3.7 Barometric pressure ..........................................109
6.3.8 Calculation of NPSH
A
and determination
of NPSH
3%
...................................................................109
6.4 Measurement of force ......................................................109
6.4.1 Measuring system ............................................... 110
6.4.2 Execution of force measurement .............. 111
6.5 Uncertainty in measurement of performance ..111
6.5.1 Standard demands for uncertainties ...... 111
6.5.2 Overall uncertainty ..............................................112
6.5.3 Test bed uncertainty ..........................................112
6.6 Summary .....................................................................................112
Appendix ...................................................................................... 113
A. Units ........................................................................................................114
B. Control of test results .................................................................. 117
Bibliography ...........................................................................................122
Standards...................................................................................................123
Index ........................................................................................................... 124
Substance values for water ..........................................................131
List of Symbols .......................................................................................132
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