Centrifugal Pumps Design and Application 2nd ed - Val S. Lobanoff, Robert R. Ross (Butterworth-Heinemann, 1992)

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NPSH 89 Figure 8-4. Pressure loss between suction nozzle and leading edge of impeller vane. constant and varying the capacity, or by holding the speed constant and reducing the suction pressure at various capacities. Either of these methods will produce a breakdown in the head characteristic as shown in Figure 8-5, indicating a condition under which the performance of the pump may be impaired. Accurately determining the inception of cavitation requires extreme control of the test and involves sophisticated instrumentation. The Hydraulic Institute has permitted a drop in head of 3 % to be accepted as Figure 8-5. Loss in head during cavitation test.
90 Centrifugal Pumps: Design and Application evidence that cavitation is present under test conditions. They do caution, however, that where it is important to establish normal operation with an appreciable margin over the minimum required NPSH, values as low as 1 % should be used. They fiirther caution, that the pump should be operated above the break-away sigma if noise and vibration are to be avoided. influence of Suction Specific Speed (N ss ) When evaluating NPSHR one should always refer to the suction specific speed (N ss ) and not to sigma, whose value depends on the head developed. Thus the same impeller when tested before and after a diameter trim will show different values of sigma yet will behave identically under cavitation. In comparing cavitation performance and predicting NPSHR, we prefer to use the suction specific speed parameter. This can be applied in the same manner as sigma yet has more significance as it relates only to the inlet conditions and is essentially independent of discharge geometries and pump specific speed. Figure 8-6 shows suction velocity triangles for N S s from 7,000 to 16,000. It graphically shows that as suction specific speed increases, normal vane entrance angle becomes flatter, C MJ relative to shaft becomes smaller, and peripheral velocity at impeller eye becomes greater. The ratio of CMI to LJ t for higher suction specific speed, is very small and chances for cavitation are greatly increased. This cavitation would appear for the following reason: To move liquid from one point to another, a change of pressure gradient must take place. But as CMI (velocity) is reduced, velocity head, V 2 /2g, is also reduced. When it becomes lower than the head required to overcome impeller entrance losses, the liquid will backflow creating cavitation and pump damage. Figure 8-7 represents a test of a four-inch pump with eight different suction specific speed impellers. Best efficiency point of all impellers is the same. Impeller profile is also the same, but impeller eye geometry is different for each suction specific speed. Some tests on different types of pumps might show different results, but the trend should be the same. This test shows the stable cavitation-free window for seven suction specific speeds and could be used as a guide for pump selection. High Speed Pumps The prediction methods and NPSH testing just described under moderate speed pumps are valid and well substantiated for low- to moderatespeed pumps. It is our opinion, however, that neither method will ensure
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CENTRIFIUGAL PUMPS Design & applica
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CENTRIFUGAL PUMPS Design & Applicat
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Contents Preface —..... —......
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ern Pumps, Mine Dewatering Pumps. W
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Stage Pumps. Single-Suction Single-
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Preface When Val and I decided to c
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CENTRIFUGAL PUMPS Design & applicat
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Part 1 Elements of Pump Design
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1 Introduction System Analysis for
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Introduction 5 Figure 1-2. The syst
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Introduction 7 mate responsibility
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Introduction 9 Figure 1-6. Maximum
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2 Specific Speed and Modeling Laws
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Specific Speed and Modeling Laws 13
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Figyre 2-7, New pump from model pum
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Impeller Design 29 Figure 3-1. Requ
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Impeller Design 31 Figure 3-4. Capa
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Impeller Design 33 Step 8: Estimate
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Impeller Design 35 Figure 3-7. Volu
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impeller Design 37 (2) 5 , as final
Page 54 and 55: Impeller Design 39 The vane develop
Page 56 and 57: Impeller Design 41 Figure 3-12. Are
Page 58 and 59: impeller Design 43 Figure 3-16. Inf
Page 60 and 61: 4 General Pump Design It is not a d
Page 62 and 63: General Pump Design 4? Figure 4-1.
Page 64 and 65: General Pump Design 49 designed and
Page 66 and 67: Volute Design 51 Figure 5-1. Volute
Page 68 and 69: Volute Design 53 Figure 5-2. Radial
Page 70 and 71: Volute Design 55
Page 72 and 73: Volute Design 57 Figure 5-4. Effici
Page 74 and 75: Volute Design 59 Figure 5-5. Typica
Page 76 and 77: Volute Design 61 Figure 5-8. Univer
Page 78 and 79: Volute Design S3 Manufacturing Cons
Page 80 and 81: 6 Design of Multi-Stage Casing Mult
Page 82 and 83: Design of Multi-Stage Casing 67 How
Page 84 and 85: Design of Multi-Stage Casing 69 Fig
Page 88 and 89: Design of Multi-Stage Casing 73 sec
Page 92 and 93: 7 Double-Suction Pumps and Side-Suc
Page 94 and 95: Double-Suction Pumps 79 two. Experi
Page 96 and 97: Double-Suction Pumps 81 Figure 7-3.
Page 98 and 99: Double-Suction Pumps 83 LOCATION AR
Page 100 and 101: 8 NPSH The expressions NPSHR and NP
Page 102 and 103: NPSH 87 Predicting NPSHR The other
Page 106 and 107: NPSH 91 SUCTION VELOCITY TRIANGLES
Page 108 and 109: NPSH 93 Figure 8-8. Performance cur
Page 110 and 111: NPSH 95 Figure 8-10. Leakage across
Page 112 and 113: NPSH 97 Figure 8-13. Plate inserts
Page 114 and 115: NPSH 99 Figure 8-17. Influence of p
Page 116 and 117: NPSH 101 Figure 8-19. Estimating K
Page 118 and 119: NPSH 103 Step 3: Determine KI* From
Page 120 and 121: Figure 8«22. Calculating NPSHA for
Page 122 and 123: NPSH 107 Figure 8-24. NPSHR cavitat
Page 124 and 125: NPSH 109 Notation KI Friction and a
Page 126 and 127: Part 2 Application
Page 128 and 129: 9 by Erik B. Fiske BW/JP Internatio
Page 130 and 131: Vertical Pumps 115 Figure 9-2. Well
Page 132 and 133: Vertical Pumps 117 Figure 9-4. Subm
Page 134 and 135: Vertical Pumps 119 Figure 9-6. Inst
Page 136 and 137: Vertical Pumps 121 Figure 9-8. Barr
Page 138 and 139: Vertical Pumps 123 • Loading pump
Page 140 and 141: Vertical Pumps 125 Wet Pit Pumps Th
Page 142 and 143: Vertical Pumps 127 • Fresh water
Page 144 and 145: Vertical Pumps 129 Condensate and H
Page 146 and 147: Vertical Pumps 131 mally insulate w
Page 148 and 149: Vertical Pumps 133 Figure 9-15. Imp
Page 150 and 151: Vertical Pumps 135 checked for corr
Page 152 and 153: Vertical Pumps 137 crating paramete
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10 Pipeline Pipe line, Waterflood,
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Pipeline, Waterflood and CO 2 Pumps
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Pipeline, Waterfiood and CO 2 Pumps
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Figure 10-11. Performance change wi
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Figure 10-13. Seven-stage pump dest
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Pipeline, Waterflood and COa Pumps
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11 By Edward Gravelle Sundstrand Fl
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High Speed Pumps 175 History and De
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High Speed Pumps 177 Figure 11-2. (
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High Speed Pumps 179 some portion o
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High Speed Pumps 181 This is to say
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High Speed Pumps 183 This expressio
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High Speed Pumps 185 Figure 11-3. P
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High Speed Pumps 187 As an aside, p
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High Speed Pumps 189 Figure 11-5. I
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High Speed Pumps 191 Figure 11-7. I
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High Speed Pumps 193 Figure 11-9. R
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High Speed Pumps 195 Figure 11-10.
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High Speed Pumps 19? Figure 11-11.
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High Speed Pumps 199
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High Speed Pumps 201 Figure 11-13.
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High Speed Pumps 203 nal bearings a
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High Speed Pumps 205 Barske, U, M.,
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Double-Case Pumps 207 jected to ext
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Double-Case Pumps 209 Figure 12-3.
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Double-Case Pumps 213 ally by split
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Double-Case Pumps 215 The throttle
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Figure 12-11. pump for 4,000 psi In
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Double-Case Pumps 219 so that the t
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Doubte-Case Pumps 223 Volute Casing
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Double-Case Pumps 225 5. Survey of
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Slurry Pumps 227 An approximate com
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Slurry Pumps 229 Figure 13-2. Nomog
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Slurry Pumps 231 Table 13-2 Alloys
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Slurry Pumps 233 Figure 13-3. Class
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Figure 13-4, (A) (B) (C)
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Slurry Pumps 237 There is little to
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Figyre 13-7, (courtesy Pumps, Inc.)
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Flgyr« 13-8, with (courtesy Goulds
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Slurry Pumps 243 ing the pump speed
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Slurry Pumps 245 Where there exists
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Hydraulic Power Recovery Turbines 2
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Figure 14-14. Internally adjustable
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14-22, Flow of hydraulic recovery a
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15 by Frederic W. Buse Ingersolf-Ra
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Chemical Pumps Metallic and Nonmeta
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Driver Chemical Pumps Metallic and
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Part3 Mechanical Design
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16 Shaft Design and Axial Thrust Sh
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Shaft Design and Axial Thrust 335 S
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Shaft Design and Axial Thrust 337 W
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Shaft Design and Axial Thrust 339 T
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Shaft Design and Axial Thrust 341 b
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Shaft Design and Axial Thrust 343 K
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Double-Suction Single-Stage Pumps S
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Shaft Design and Axial Thrust 347 F
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D (with subscript) P D P s T T (wit
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Mechanical Seals 355 Figure 17-1. M
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Mechanical Seats 357 Figure 17-2B.
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Mechanical Seals 359 Figure 17-2D.
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Mechanical Seals 361 Figure 17-4. H
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Mechanical Seals 363 Pressure-Veloc
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Mechanical Seals 365 The temperatur
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Mechanical Seals 367 Figure 17-7. B
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Mechanical Seals 369 Figure 17-9. P
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Mechanical Seals 371 where C 3 = 53
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Mechanical Seals 373 Classification
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Mechanical Seals 375 Double seals m
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Mechanical Seals 377 less than 100,
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Mechanical Seals 379 Figure 17-19.
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Mechanical Seals 381 Table 17-4 Tem
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Mechanical Seats 385 steam, is to p
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Mechanical Seats 38? rather than a
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Mechanical Seals 389 Mechanical Sea
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Mechanical Seals 391 seal to work i
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Mechanical Seals 395 The measured l
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Mechanical Seals 39? Figure 17-34.
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Mechanical Seals 401 This design is
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Mechanical Seals 403 alignment, par
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Mechanical Seats 419 Figure 17-58.
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Vibration and Noise in Pumps 421 Re
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Vibration and Noise in Pumps 423 me
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Vibration and Noise in Pumps 425 in
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Vibration and Noise in Pumps 427 pr
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Vibration and Noise in Pumps 429 ot
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Vibration and Noise in Pumps 431 Fi
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Vibration and Noise in Pumps 433 fi
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Vibration and Noise in Pumps 435 pr
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Vibration and Noise in Pumps 437 up
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Vibration and Noise in Pumps 441 na
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Vibration and Noise in Pumps 443 A
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Vibration and Noise in Pumps 453 Re
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Vibration and Noise in Pumps 457 Ac
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Vibration and Noise in Pumps 461 As
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Vibration and Noise in Pumps 463 ci
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Vibration and Noise in Pumps 467 sp
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Vibration and Noise in Pumps 469 Be
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Vibration and Noise in Pumps 475 Vi
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Vibration and Noise in Pumps 489 pe
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Vibration and Noise in Pumps 491 th
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Vibration and Noise in Pumps 4S3 fo
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Part 4 Extending Pump Life
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19 by Malcolm G. Murray, Jr. Murray
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Alignment 499 Figure 19-2. Pump dam
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Alignment 501 The best designs fail
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Table 19-1 Vertical Alignment Movem
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Table 19-2 Continued Horizontal Ali
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Alignment 507 bearing motors becaus
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Alignment 509 meet results. It shou
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Alignment 511 Determination of Tole
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Table 19-3 Continued Primary Alignm
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Alignment 515 Figure 19-3 A & B. Tw
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Table 19*4 Continued Methods of Cal
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Alignment 510 parallelism/perpendic
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Alignment 521 Table 19-5 continued
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Alignment 523 3. Essinger, J. N., B
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Rolling Element Bearings and Lubric
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Roiling Element Bearings and Lubric
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Roiling Element Bearings and Lubric
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Failure Analysis Mechanical Seal Re
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Table 21-2 Causes of Seal Failures
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Mechanical Seal Reliability 561 ^mi
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Mechanical Seal Reliability 563 Sea
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Mechanical Seal Reliability 565 run
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Reliability Mechanical Seal Reliabi
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Index A thermal growth, 519-522 ver
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Critical speed analysis. See also V
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Index 573 inlet angle, 37 classific
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Index 575 Shaft design, 333-343 ind
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double, 52-54 velocity ratio, 50-51
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Centrifugal Pumps Design and Application 2nd ed - Val S. Lobanoff, Robert R. Ross (Butterworth-Heinemann, 1992)

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