GRUNDFOS RESEARCH AND TECHNOLOGY

1 The centrifugal PumpGRUNDFOSRESEARCH AND TECHNOLOGYThe centrifugal Pump5 All rights , electronic, photographic or other reproduction or copying from this book or parts of it are according to the present Danish copyright law not allowed without written permission from or agreement with GRUNDFOS Management A/S. GRUNDFOS Management A/S cannot be held responsible for the correctness of the information given in the book. Usage of information is at your own responsibility. 6 PrefaceIn the Department of Structural and Fluid Mechanics we are happy to present the first English edition of the book: The centrifugal Pump.

2 We have written the book because we want to share our knowledge of pump hy-draulics, pump design and the basic pump terms which we use in our daily work. The centrifugal Pump is primarily meant as an inter-nal book and is aimed at technicians who work with development and construction of pump components. Furthermore, the book aims at our future colleagues, students at universities and engineering colleges, who can use the book as a reference and source of inspira-tion in their studies. Our intention has been to write an introductory book that gives an overview of the hy-draulic components in the pump and at the same time enables technicians to see how changes in construc-tion and operation influence the pump performance.

3 In chapter 1, we introduce the principle of the centrifu-gal pump as well as its hydraulic components, and we list the different types of pumps produced by GRUNDFOS . Chapter 2 describes how to read and understand the pump performance based on the curves for head, pow-er, efficiency and NPSH. In chapter 3 you can read about how to adjust the pump s performance when it is in operation in a system. The theoretical basis for energy conversion in a centrifu-gal pump is introduced in chapter 4, and we go through how affinity rules are used for scaling the performance of pump impellers.

4 In chapter 5, we describe the differ-ent types of losses which occur in the pump, and how the losses affect flow, head and power consumption. In the book s last chapter, chapter 6, we go trough the test types which GRUNDFOS continuously carries out on both assembled pumps and pump components to ensure that the pump has the desired performance. The entire department has been involved in the devel-opment of the book. Through a longer period of time we have discussed the idea, the contents and the structure and collected source material. The framework of the Danish book was made after some intensive working days at Himmelbjerget.

5 The result of the department s engagement and effort through several years is the book which you are holding. We hope that you will find The centrifugal Pump use-ful, and that you will use it as a book of reference in you daily work. Enjoy!Christian Brix Jacobsen Department Head, Structural and Fluid Mechanics, R&T7 ContentsChapter 1. Introduction to centrifugal Pumps .. Principle of centrifugal pumps .. The pump s hydraulic components ..13 Inlet flange and inlet ..14 Impeller ..15 Coupling and drive ..17 Impeller seal ..18 Cavities and axial bearing.

6 19 Volute casing, diffuser and outlet flange ..21 Return channel and outer sleeve .. Pump types and systems ..24 The UP pump ..25 The TP pump ..25 The NB pump ..25 The MQ pump ..25 The SP pump ..26 The CR pump ..26 The MTA pump ..26 The SE The SEG pump .. Summary ..27 Chapter 2. Performance curves .. Standard curves .. Pressure .. Absolute and relative pressure .. Head .. Differential pressure across the pump ..35 Total pressure difference ..35 Static pressure difference ..35 Dynamic pressure difference ..35 Geodetic pressure difference.

7 Energy equation for an ideal flow .. Power ..38 Speed .. Hydraulic power .. Efficiency .. NPSH, Net Positive Suction Head .. Axial Radial thrust .. Summary ..45 Chapter 3. Pumps operating in systems .. Single pump in a Pumps operated in parallel .. Pumps operated in series .. Regulation of pumps ..51 Throttle regulation ..52 Regulation with bypass valve ..52 Start/stop regulation ..53 Regulation of speed .. Annual energy consumption .. Energy efficiency index (EEI).. Summary ..58 Chapter 4. Pump theory .. Velocity triangles.

8 60 Inlet ..62 Outlet .. Euler s pump equation .. Blade shape and pump curve .. Usage of Euler s pump equation .. Affinity rules ..68 Derivation of affinity rules .. Pre-rotation .. Slip .. The pump s specific speed .. Summary ..75 Chapter 5. Pump losses .. Loss types .. Mechanical losses ..80 Bearing loss and shaft seal loss .. Hydraulic losses ..80 Flow Mixing loss at cross-section expansion ..86 Mixing loss at cross-section reduction ..87 Recirculation loss ..89 Incidence loss ..90 Disc friction ..91 Leakage.

9 Loss distribution as function of specific speed .. Summary ..95 Chapter 6. Pumps tests .. Test types .. Measuring pump performance ..99 Flow ..100 Pressure ..100 Temperature ..101 Calculation of head ..102 General calculation of head ..103 Power consumption ..104 Rotational speed .. Measurement of the pump s NPSH ..105 NPSH3% test by lowering the inlet pressure ..106 NPSH3% test by increasing the flow ..107 Test beds ..107 Water quality ..108 Vapour pressure and Reference plane ..108 Barometric pressure.

10 109 Calculation of NPSHA and determination of NPSH3% .. Measurement of force ..109 Measuring system ..110 Execution of force measurement .. Uncertainty in measurement of performance .. 111 Standard demands for uncertainties ..111 Overall uncertainty ..112 Test bed uncertainty .. Summary ..112 Appendix ..113A. Units ..114B. Control of test results ..117 Bibliography ..124 Substance values for water ..131 List of Symbols ..132 910 Chapter 1 Introduction to centrifugal Principle of the centrifugal Hydraulic components Pump types and SummaryOutletImpellerInlet1212 OutletImpellerInletDirection of rotation1.