HI 1.6(2000)

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ANSI/HI 1.6-2000

American National Standard for

Centrifugal Pump Tests

Sponsor

Hydraulic Institute

www.pumps.org

Approved October 27 , 1999

American National Standards Institute, Inc.

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American National 8tandard

Published By

Approval of an American National Standard requires verification by ANSI that the requirements for due process, consensus and other criteria for approval have been met by the standards developer.

Consensus is established when, in the judgement of the ANSI Board of Standards Review, substantial agreement has been reached by directly and materially a仟ectedinterests. Substantial agreement means much more than a simple majority, but not necessarily unanimity. Consensus requires that all views and objections be considered ,

and that a concerted effort be made toward their resolution.

The use of American National Standards is completely voluntary; their existence does not in any respect preclude anyone, whether he has approved the standards or not, from manufacturing, marketing, purchasing, or using products, processes, or procedures not conforming to the standards.

The American National Standards Institute does not develop standards and will in no circumstances give an interpretation of any American National Standard. Moreover, no person shall have the right or authority to issue an interpretation of an American National Standard in the name of the American National Standards Institute. Requests for interpretations should be addressed to the secretariat or sponsor whose name appears on the title page of this standard.

CAUTION NOTICE: This American National Standard may be revised or withdrawn at any time. The procedures of the American National Standards Institute require that action be taken periodically to reaffirm, revise, or withdraw this standard. Purchasers of American National Standards may receive current information on all standards by calling or writing the American National Standards Institute.

Hydraulic Institute 9 Sylvan Way, Parsippany, NJ 07054-3802

www.pumps.org

Copyright 2000 @ Hydraulic Institute AII rights reserved.

No pa此 ofthis publication may be reproduced in any form , in an electronic retrieval system or otherwise, without prior written permission of the publisher.

Printed in the United States of America

ISBN 1-880952-30-0

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\-. ...- Contents

Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. v

Page

1.6

1.6.1

1.6.2

1.6.3

1.6.4

1.6.5

1.6.6

1.6.7

1.6.8

1.6.9

1.6.10

1.6.11

1.6.12

1.6.13

1.6.14

Test. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1

Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1

Types of tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1

Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1

Hydrostatic test. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Performance test. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Net positive suction head required test (optional). . . . . . . . . . . . . . . 19

Mechanical test (optional). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Priming time test. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Measurement of rate of flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Head - measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Power measurement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 30

Speed measurement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Temperature measurement and instruments . . . . . . . . . . . . . . . . . . 32

Model tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

\d ) Appendix A References.......................................... 35

Appendix B Index.............................................. 36

Figures

1.113 - Horizontal unit - (Single or double suction) (Double suction not shown) . . . . . . . . . . . . . . . . . . . . . . .圖 .................4

1.114 - Vertical single suction pump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

1.115-Ve此ical double suction pump .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

竹筒- Test with suction lift. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 11

1.117 一 Open or closed tank . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 13

叫他一 Pump performance (all data is corrected to rated speed) . . . . . . . . .. 16

1.119 - Suppression type NPSH test with constant level sump. . . . . . . . . . .. 19

1.120 - Level control NPSH test with deep sump supply. . . . . . . . . . . . . . . . . 20

1.121 - Vacuum and/or heat control NPSH test with closed loop . . . . . . . . . . 20

1.122 - NPSH test with rate of flow held constant . . . . . . . . . . . . . . . . . . . . . . 21

1.123 一- NPSH test with suction head held constant. . . . . . . . . . . . . . . . . . . . . 21

1.124 - NPSH test with flow rate held constant . . . . . . . . . . . . . . . . . . . . . . . . 22

1.125 - Suction line for static lift test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

1.126 - Pressure tap opening ..................................... 26 、.-/

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1.127 - Welded-on pressure tap opening . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

1.128 - Single tap connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

1.129 一 Loop manifold connecting pressure taps. . . . . . . . . . . . . . . . . . . . . . . 30

1.130 - Gauge connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Tables

1.18 一-Symbols.................................................. 2

1.19 - Subscripts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 3

1.20 - Recommended instrument calibration interval .. . . . . . . . . . . . . . . . .. 12

1.21 一- Straight pipe required following any fitting before venturi meter in diameters of pipe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

1.22 一- Straight pipe required following any fitting before nozzle or orifice plate meter in diameters of pipe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

1.23 - Straight pipe required following downstream pressure tap of a nozzle or orifice plate meter before any fitting in diameters of pipe . . . . . . .. 28

IV

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Foreword (Not part of Standard)

Purpose and aims of the Hydraulic Institute

The purpose and aims of the Institute are to promote the continued growth and well-being of pump manufacturers and further the interests of the public in such matters as are involved in manufacturing, engineering, distribution, safety, transpo吋ation and other problems of the indust句， and to this end , among other things:

a) To develop and publish standards for pumps;

b) To collect and disseminate information of value to its members and to the public;

c) To appear for its members before governmental departments and agencies and other bodies in regard to matters affecting theindustry;

的 To increase the amount and to improve the quality of pump service to the public;

e) To suppo吋 educational and research activities;

f) To promote the business interests of its members but not to engage in business of the kind ordinarily carried on for profit or to perform particular services for its members or individual persons as distinguished from activities to improve the business conditions and lawful interests of all of its members.

Purpose of 5tandards

1) Hydraulic Institute Standards are adopted in the public interest and are designed to help eliminate misunderstandings between the manufacturer, the purchaser and/or the user and to assist the purchaser in selecting and obtaining the proper product for a particular need.

2) Use of Hydraulic Institute Standards is completely voluntary. Existence of Hydraulic Institute Standards does not in any respect preclude a member from manufacturing or selling products not conforming to the Standards.

Definition of a 5tandard of the Hydraulic Institute

Quoting from Article XV, Standards, of the By-Laws of the Institute, Section B:.

“An Institute Standard defines the product, material, process or procedure with reference to one or more of the following: nomenclature, composition, construction, dimensions, tolerances, safety, operating characteristics, performance, quality, rating, testing and service for which designed."

Comments from users

Comments from users of this Standard will be appreciated, to help the Hydraulic Institute prepare even more useful future editions. Questions arising from the content of this Standard may be directed to the Hydraulic Institute. It will direct all such questions to the appropriate technical committee for provision of a suitable answer.

If a dispute arises regarding contents of an Institute publication or an answer provided by the Institute to a question such as indicated above, the point in question shall be referred to the Executive Committee of the Hydraulic Institute, which then shall act as a Board of Appeals.

V

Revisions

The Standards of the Hydraulic Institute are subject to constant review, and revisions are undertaken whenever it is found necessary because of new developments and progress in the art. If no revisions are made for five years, the standards are reaffirmed using the ANSI canvass procedure.

Scope

This Standard is for centrifugal , sealless centrifugal and regenerative turbine pumps of all industrial types except vertical multistage diffuser type. It includes detailed procedures on the setup and conduct of hydrostatic and performance tests of such pumps.

Several methodologies to test centrifugal and vertical pump equipment are available to pump manufacturers, users and other interested parties. The United States has two sets of pump test standards which represent 的vo approaches to conducting and evaluating pump pe吋Ormance. One, promulgated by the American Society of Mechanical Engineers (ASME) and designated PTC 8.2, Centrifugal Pumps, provides for two levels of tests in which the test procedures are less restrictive. The ASME Code relies on the pa討ies to the test to agree beforehand on the Scope and Conduct of the test and does not specify how the test results shall be used to compare with guarantee. The ASME is especially suited to highly detailed pump testing, whereas HI Standards detail test scope, conduct and acceptance criteria, and are thus suited to commercial test practices. ASME Codes do not permit the use of acceptability tolerances in reporting results , while the HI Standards do. It is recommended that the specifier of the test standard become familiar with both the ASME Code and the HI Standards before selecting the one best suited for the equipment to be tested, since there are a number of other differences between the two which may a仟8ct the accuracy or cost of the tests.

80th the ASME and HI Standards can be used for testing in either field or factory installations. The detailed requirements of the ASME Test Code are intended to reduce the effect of various installation arrangements on performance results and are applied more to field testing. The HI Standard specifies test piping and more controllable conditions which is more suitable to factory testing. The HI Standards do not address field testing. Surveys have shown that both ASME and HI Standards have been applied successfully to applications from small chemical pumps (1 hp) to large utility pumps (over 5000 hp).

Units of Measurement

Metric units of measurement are used; and corresponding US units appear in brackets. Charts, graphs and sample calculations are also shown in both metric and US units.

Since values given in metric units are not exact equivalents to values given in US units, it is important that the selected units of measure to be applied be stated in reference to this standard. If no such statement is provided, metric units shall govern.

VI

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Consensus for this standard was achieved by use of the Canvass Method

The following organizations, recognized as having an interest in the standardization of centrifugal pumps were contacted prior to the approval of this revision of the standard. Inclusion in this list does not necessarily imply that the organization concurred with the submittal of the proposed standard to ANS I.

A. R. Wilfley & Sons ANSIMAG Inc. Bechtel Corp Black & Veatch Brown & Caldwell Camp Dresser & McKee, Inc. Carver Pump Company Cheng Fluid Systems, Inc. Crane Company, Chempump Div. Cuma S.A. Dean Pump Div. , Metpro Corp. DeWante & Stowell Dow Chemical EnviroTech Pumpsystems Essco Pump Division Exeter Energy Ltd. Partnership Fairbanks Morse Pump Corp. Fluid Sealing Association Franklin Electric GKO Engineering Grundfos Pumps Corp. lII inois Dept. of Transportation IMC - Agrico Chemical Corp. Ingersoll. Dresser Pump Company ITT Fluid Handling (B & G) ITT Fluid Technology 何T Industrial Pump Group Iwaki Walchem Corp. J.P. Messina Pump & Hydr. Cons John Crane, Inc. Krebs Consulting Service

KSB, lnc. M.W. Kellogg Company Malcolm Pirnie, Inc. Marine Machinery Association Marley Pump Company Marshall Engineered Products

Company Montana State University MWI, Moving Water Industries Oxy Chem Pacer Pumps Paco Pumps, Inc. Pinellas Cty, Gen. Serv. Dept. The Process Group, LLC Raytheon Engineers & Constructors Reddy-Buffaloes Pump, Inc. Robert Bein, Wm. Frost & Assoc. Scott Process Equipment Corp. Settler Supply Company Skidmore South Florida Water Mgmt. Dist. Sta-Rite Industries, Inc. Sterling Fluid Systems (USA), Inc. Stone & Webster Engineering Corp. Sulzer Bingham Pumps, Inc. Summers Engineering, Inc. Systecon, Inc. Val-Matic Valve & Mfg. Corp. Yeomans Chicago Corp. Zoeller Engineered Products

VII

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1.6 Test

1.6.1 5cope

This standard is limited to the testing of centrifugal pumps with clear water. The tests conducted under these standards shall be made and reported by qualified personnel.

This standard only applies to tests of the pump unless stated otherwise.

The type of test(s) performed, and the auxiliary equipment to be used, should be agreed upon by the purchaser and manufacturer prior to the test.

It is not the intent of this standard to limit or restrict tests to only those described herein. Variations in test procedures may exist without violating the intent of this standard. Exceptions may be taken if agreed upon by the parties involved without sacrificing the validity of the applicable parts of this standard.

1.6.1.1 。叫ective

This standard is intended to provide uniform procedures for hydrostatic, hydraulic, and mechanical performance testing of centrifugal pumps and recording of

\-./. the test results. This standard is intended to define test procedures which may be invoked by contractual agreement between a purchaser and manufacturer. It is not intended to define a manufacturer's standard practice

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1.6.2 Types of tests

This standard describes the following tests:

a) Performance test to demonstrate hydraulic and mechanical integrity;

Optional tests as follows when specified:

b) Hydrostatic test of pressure-containing components;

c) Net positive suction head required test (NPSHR test);

d) Mechanical test;

e) Priming time test.

For airborne sound testing see HI 9.1-9.5-2000 , Pumps - General Guidelines.

HI Centrifugal Pump Tests - 2000

1.6.2.1 Test conditions

Unless otherwise specified, the rate of flow, head, efficiency, NPSHR and priming time are based on shop tests using water corrected to 200 C (680 F). If the facility cannot test at rated speed because of limitations in power, electrical frequency or available speed change悶， the pump may be tested at between 80% and 120% of rated speed. It is permissible on pumps greater than 225 kw (300 hp) to test at speeds between 60% and 140% of rated speed.

1.6.3 Terminology

The following terms are used to designate test parameters or are used in connection with pump testings:

1.6.3.1 5ymbols

See Table 1 .18.

1.6.3.2 5ubscripts

See Table 1.19.

1.6.3.3 5pecified condition point

Specified condition point is synonymous with rated condition point.

1.6.3.4 Rated condition point

Rated condition point applies to the rate of flow, head, speed, NPSH and power of the pump as specified by the purchase order

1.6.3.5 Normal condition point

Normal condition point applies to the rate of flow, head, speed, NPSH and power at which the pump will normally operate. It may be the same as the rated condition point.

1.6.3.6 Best efficiency point (BEP)

The rate of flow and head at which the pump effiç:iency (ηp) is a maximum.

1.6.3.7 5hut 。何 (50)

The condition of zero flow where no liquid is flowing through the pump, but the pump is primed and operating.

1\.)

Table 1.18 - Symbols

Conversion Symbol Term Metric unit Abbreviation US Customary Unit Abbreviation factora

A Area square millimeter mmL square inches inL 645.2 ß (beta) Meter or orifice ratio dimensionless dimensionless

D Diameter millimeter mm inches In 25.4 ~ (delta) Difference dimensionless dimensionless η(eta) E仟iciency percent % percent %

g Gravitational acceleration meter/second/sq uared m/s2 feetlsecond/sq uared ftlsec2 0.3048 y(gamma) Specific weight pounds/cubic foot Ibl代3

h Head meter 口1 feet R 0.3048 H Total head meter 們1 feet R 0.3048 n Speed revolutions/minute rpm revolutions/minute rpm

NPSHA Net positive suction head meter 口1 feet 前 0.3048 available

NPSHR Net positive suction head meter m feet R 0.3048 required

NS Specific speed NS = nQYo/H% dimensionless dimensionless 1.162 v (nu) Kinematic viscosity millimeter squared/sec m行，2/S feet squared/second ft2/sec 92,900 π pi = 3.1416 dimensionless dimensionless p Pressure kilopascal kPa pounds/square inch pSI 6.895 P Power kilowatt kW horsepower hp 0.7457 q Rate offlow cubic meter/hour m3/h cubic feetlsecond 代3/Sec 101.94 Q Rate offlow cubic meter/hour m3/h US gallons/minute gpm 0.2271

p (rho) Density kilogram/cubic meter kg/m3 pound mass/cubic foot Ibm/ft3 16.02 s Specific gravity dimensionless dimensionless

Temperature degrees Celsius 。C degrees Fahrenheit 。F CF-32) x % τ(tau) Torque Newton - meter N.m pound-feet Ib-ft 1.356

V Velocity meter/second m/s feetlsecond ftlsec 0.3048 X Exponent none none none none Z Elevation gauge distance above meter 口1 feet 代 0.3048

or below datum

a Conversion factor x US units = metric units.

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1.6.3.8 Volume

The unit of volume shall be one of the following:

Metric: cubic meter;

US units: US gallon;

US units: cubic foot.

The specific weight of water at a temperature of 20 0 C (68 0 F) shall be taken as 9.89 kN/m3 (62.3 IbIft3). For other temperatures, proper specific weight corrections shall be made using values from the ASME steam tables.

1.6.3.9 Rate offlow (capacity) (Q)

The rate of flow of a pump is the total volume throughput per unit of time at suction conditions. It assumes no entrained gases at the stated operating conditions.

1.6.3.10 Speed (n)

The number of revolutions of the shaft in a given unit of time. Speed is expressed as revolutions per minute

HI Centrifugal Pump Tests 一 2000

1.6.3.11 Datum

The reference line or center of the pump shaft from which all elevations are measured. The elevation head (Z) to the datum is positive when the gauge is above datum and negative when the gauge is below datum.

The datum elevation is defined as follows:

For horizontal units, it shall be the centerline of the pump shaft, Figure 1.113.

For vertical single suction pumps, it shall be the entrance eye to the first stage impeller, Figure 1.114.

For vertical double suction pumps, it shall be the center of the impell前， Figure 1.115.

1.6.3.12 Head (h)

Head is the expression of the energy content of the liquid referred to a datum. It is expressed in units of energy per unit weight of liquid. The measuring unit for head is meter (feet) of liquid:

Table 1.19 - Subscripts

Subscript Term Subscript Term

Test condition or model 口10t Motor

2 Specific condition or prototype ot Operating temperature

a Absolute OA Overall unit

at訂1 Atmospheric p Pump

b Barometric S Suction

d Discharge Theoretical

dvr Driver input V Velocity

g Gauge vp Vapor pressure

max Maximum W Water

mm Minimum

3


乙and datum elevation

Figure 1.113 - Horizontal unit - (Single or double suction) (Double suction not shown)

Pump centerline

六司DatumFigure 1.114 - Vertical single suction pump

Pump centerline

Figure 1.115 - Vertical double suction pump

4

1.6.3.12.1 Gauge head (hg)

The pressure energy of the Iiquid determined by a pressure gauge or other pressure measuring device.

(Metric) hg = 旦旦9.8s

一(2.31 )(62.3)(Pg) 一 2.31 (Pg) (US units) h(J = "v'

~ r s

1.6.3.12.2 Velocity head (hv)

The kinetic energy of the liquid at a given section. Velocity head is expressed by the following equation:

。h.. = 之一v 2(g)

1.6.3.12.3 Elevation head (Z)

The potential energy of the liquid due to its elevation relative to a datum level , measured to the Iiquid surface or center of the pressure gauge.

1.6.3.12.4 Total suction head (hs)

The total suction head is the algebraic sum of the suction gauge head, the suction velocity head , and the suction elevation head:

hs = h_ + h.. + Z_ ξ"s .S

The gauge head is positive when the suction ga,uge reading is above atmospheric pressurE; and negative when the reading is below atmospheric pressure.

The velocity head is computed for the liquid velocity at the point of gauge attachment.

On pumps submerged in an open sump or open wet well , where the suction piping is considered pa吋 ofthe

pump:

hs = Zw

Where:

Zw = Vertical distance of the sump free water surface from datum.

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1.6.3.12.5 Total suction lift

When the total suction head is negative, it is often called total suction lift.

1.6.3.12.6 Total discharge head (hd)

The total discharge head is the algebraic sum of the discharge gauge head, discharge velocity head, and the discharge elevation head. It is computed for the liquid velocity at the discharge pressure tap, and the elevation head Zd' measured at the pressure gauge:

h.... = h_ +h.. +Z d - "gd ' "vd

1.6.3.12.7 Total head (H)

This is the measure of the work increase per unit weight of the liquid, imparted to the liquid by the pump, and is therefore the algebraic difference between the total discharge head and the total suction head.

a) Where positive suction head exists, the total head is the total discharge head minus the total suction head:

H = hd-hs

or

H=(hgd+hvd+Zd)(hgs+hvs+Zs)

Combining terms, the general expression for total head is:

H=(hgd-hgs)+(hvd-hvs)+(Zd-Zs)

的 for pumps submerged in sumps:

H = h_ +h" +Z，， -Z山:1 d Vd

c) Where negative suction head exists, the total head is the total discharge head plus the total suction lift.

Since the complete characteristics of a pumping system determine the total head requirements, this value can only be specified by the user.

1.6.3.12.8 Atmospheric head (hatm)

Local atmospheric pressure expressed in meters (feet).


1.6.3.12.9 Effects of compressibility of liquid on total head

In the preceding formulas, the work accomplished in compressing the liquid has been ignored. To evaluate the total head more accurately when pumping to high pressure, this factor should be taken into consideration. For most liquids, it may be assumed that a straight line relationship exists between pressure and volume. With this assumption, the above total head formula becomes:

H = r~叭門It is suggested that this relationship be used if the dif.圖

ference between Yd and 芯， near best e仟iciency point, is 0.2% or more.

Example: (Metric) Correction of total head for compressibility. Given Water Conditions:

ts = 1770 C (suction temperature);

Ps = 1380 kPa (suction pressure);

td = 1820 C (discharge temperature);

Pd = 32400 kPa (discharge pressure);

At suction conditions:

Ps = 1480 kPa; 九= 17rC

From steam tables, Suction specific volume = 890.5 kg/m3

At discharge conditions:

Pd = 32500 kPa; td = 1820 C

From steam tables, Discharge specific volume = 904.5 kg/m3

Specific volume = 1/specific weight = 1/ythen:

5


This value should be added to the terms:

(hvd hvs)and (Zd Zs)

to obtain the total head.

Example: (US units) Correction of total head for compressibility. Given Water Conditions:

ts = 350 0 F (suction temperature);

Ps = 200 psig (suction pressure);

td = 360 0 F (discharge temperature);

Pd = 4700 psig (discharge pressure);

Reference: Keenan and Keys, Steam Té的les， Thermodynamic Properties of Water, John Wiley and Sons, lnc.

At suction conditions:

Ps = 215 psia; 已= 3500 F

From steam tables, Suction specific volume = .01800 ft3/lb

At discharge conditions:

Pd = 4715 psia; 的= 3600 F

From steam tables, Discharge specific volume = .01772 位3/lb

Specific volume = 1/specific weight = 1/ythen:

(Pdf)?+主l

(.01772 + .01800) 2=11,57O ft

γhis value should be added to the terms:

(hll.-h ll ) and (Z卅一 Z，，)• a .5

to obtain the total head.

6

1.6.3.12.10 Net positive suction head available (NPSHA) ~.

Net positive suction head available (NPSHA) is the total suction head of liquid absolute, determined at the suction nozzle and referred to datum, less the absolute vapor pressure of the liquid in head of liquid pumped:

NPSHA = h~ - h"n -a

Where:

h ", = Total suction head in Meters (feet) absolute -a

= hatm+hs

or

NPSHA = hatm+hs-hvp

Example: (Metric) A four-stage boilerfeed pump having a 100-mm inside diameter suction and a 75-mm inside diameter discharge is rated at a flow rate of 91 m3/h against a total head of 274 m handling water at 1160 C, and running at 3550 rpm. The suction gauge reading is 145 kPa and the gauge center location is 0.15 m below impeller inlet datum, and atmospheric pressure is 98 kPa.

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To calculate the net positive suction head available (NPSHA) to the pump in the field:

1000 NPSHA = 一一一一 (Pt:>- P,m) + h", (gxp)' a vμ 。

Pvp = 172 kPa (from steam tables)

y = Specific weight = 947.3 kg/m3

Velocity in the 100-mm inside diameter suction:

v= 91

= 3.2 m/s 0.1叫 :36OO

.,2 Velocity head (h v) = ~一

5' 2g

m n/FO nu --2

一β

門/』-nu

qu一×

一月4

一一s v

h

h_=h_+h..+Z~ :3 8 .S

r=\ ( 1000 ì h_ = 144.8xl IVVV 1+0.52-0.15 = 16.2 m

s - \..947.3 x 9.81)

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1000 NPSHA = ,... ，， ;V~VA'" ,, (98-172) + 16.2 = 8.2 m 9.81 x 947.3

Examp給: (US units) A four-stage boiler feed pump having a 4-inch inside diameter suction and a 3-inch inside diameter discharge is rated at a flow rate of 400 gpm against a total head of 900 feet handling water at 240o F, and running at 3550 rpm. The suction gauge reading is 21 psig , the gauge center location is 0.5 feet below impeller inlet datum, and atmospheric pressure is 29 inches Hg.

29 13.6 P", tm = 29" of Hg = 一×一一一= 14.2 psia é:J LfTI 12 2.31

NOTE: specific gravity of mercu叩= 13.58 and

ft of liquidx s Patm in psi rm ... ,..._. 2.31

To calculate the net positive suction head available (NPSHA) to the pump in the field:

144 NPSHA=7(Pa Pvp)+hs

Pvp = 25.0 psia (from steam tables)

y = Specific weight = 59.1 Ib/ft3

Velocity in the 4-inch inside diameter suction:

400 x .321 v= 一一一一= 10.2 ftlsec

:(4)2

,,2 Velocity head (hv) = 二一

s' 2g

hv= 旦旦旦= 1.6 feet s 2 x 32.2

h_=h_+h..+Z_

21 x 144 s 一一一一一+ 1.6 一 0.5 = 52.3 feet

59.1

144 NPSHA = 一一;.( 14.2 - 25.0) + 52.3 = 26.1 feet 59.1

1.6.3.12.刊

(NPSHR) Net positive suction head required

Net positive suction head required (NPSHR) is the total suction head of liquid absolute determined at the first stage impeller datum less the absolute vapor

HI Centrifugal Pump Tests 一 2000

pressure of the liquid in head of liquid pumped, required to prevent more than 3% loss in total head from the first stage of the pump at a specific rate of flow.

1.6.3.13 Power (P)

1.6.3.13.1 Pump input power (Pp)

The power delivered by the driver to the pump input shaft. It is also called brake horsepower.

1.6.3.13.2 Electric driver input power (P mot)

The electrical input to the driver expressed in kilowatls (horsepower).

1.6.3.13.3 Pump output power (Pw)

The power imparted to the liquid by the pump. It is also called water horsepower.

QxHxs (Metric) P w =一一一一

367

QxHxs (US units) P w = 一一一-

w 3960

1.6.3.13.4 Pump efficiency (llp)

The ratio of the pump output power (Pw) to the pump input power (Pp); that 峙， the ratio of the liquid horsepower to the brake horsepower expressed in percent:

ηp 乎 x 100 .p

1.6.3.13.5 Overall efficiency (1l0A)

The ratio of the pump output power (Pw) to the energy supplied to the driver (Pmot) expressed in percent. This e仟iciency takes into account losses in both the pump and the driver:

p …

η OA = 古主- x 100 • mot

1.6.4 Hydrostatic test

1.6.4.1 Hydrostatic test objective

To demonstrate that the pump when subjected to hydrostatic pressure(s) will not leak or fail structurally. For purposes of this requirement, the containment of liquid means only prevention of its escape through

7


the external surfaces of the pumps, normally to atmosphere.

1.6.4.2 Hydrostatic test parameters

Each part of the pump which contains liquid under pressure shall be capable of withstanding a hydrostatic test at not less than the greater of the following:

150% of the pressure which would occur in that part when the pump is operating at rated condition for the given application of the pump, except thermoset pa吋s.

125% of the pressure which would occur in that part when the pump is operating at rated speed for a given application , but with the pump discharge valve closed.

Due to the irreversible damage that can occur to the reinforcement of thermoset parts that are put under excessive pressure, hydrostatic test pressure shall be 1.1 times the maximum design pressure. The manufacturer should be able to verify through test records that adequate sampling was done to prove that the pa前s can sustain 1.5 times the design pressure. When a 1.5 hydrostatic test pressure on thermoset parts is requested , all parties should agree to the consequences of possible irreversible damage.

In all instances, suction pressure must be taken into account.

8

Components or assembled pumps: The test shall be conducted on either the liquid-containing components or the assembled pump.

Components: The test shall be conducted on the liquid-containing components such as the casing and end covers. Care must be taken not to impose pressure in excess of 150% of design on areas designed for lower pressure operation. Test flanges or cylinders can be used for isolating differential pressure.

Assembled pump: The test shall be conducted on the entire liquid-containing area of the pump, but care must be taken not to impose pressure in excess of 150% of design on areas such as suction volutes or mechanical seal areas.

Test duration: Test pressure shall be maintained for a sufficient period of time to permit complete examination of the parts under pressure. The hydrostatic test shall be considered satisfacto叩

when no leaks or structural failure are observed for a minimum of 3 minutes for pumps 75 kW (100 /"\ horsepower) and below, or 10 minutes above 75 kW (100 horsepower).

Test Iiquid: Test liquid shall be water or oil having a maximum viscosity of 32 Cst (150 SSU) at test temperature.

Temperature: If the part tested is to operate at a temperature at which the strength of material is below the strength of the material at room temperatu舟， the hydrostatic test pressure shall be multiplied by a factor obtained by dividing the allowable working stress for the material at room temperature by that at operating temperature. This pressure thus obtained shall then be the minimum pressure at which hydrostatic pressure shall be performed. The data sheet shall list the actual hydrostatic test pressure.

1.6.4.3 Hydrostatic test procedure

Items to be tested shall have all the openings adequately sealed. Provisions shall be made to vent all the air at the high points on the item. The item shall be filled with the test liquid, pressurized, and the test pressure shall be maintained for the duration of the test. No leakage through the item tested shall be visible; however, leakage through the stuffing-box packing shall be permitted.

1.6.4.4 Hydrostatic test records

Complete written or computer records shall be kept of all pe此inent information and kept on file , available to the purchaser by the test facility, for two years. This information shall include:

的 Identification by model, size, serial number;

b) Test liquid;

c) Maximum allowable working pressures and temperature;

d) Hydrostatic test pressure and test duration;

e) Date of test;

f) Identity of personnel in charge.

/舟、

f何四、\

1.6.5 Performance test

、、、啥_/1.6.5.1 Performance test acceptance tolerances

The acceptance tolerance applies to the specified condition point only, not to the entire performance curve.

While pumps must be closely checked for satisfactory mechanical operation during performance testing, the degree and extent of such checking is independent of the level of acceptance tolerances.

The minimum number of test points for level “A" shall be 7, and the minimum number for level “B" shall be 5. See Section 1.6.5.3 for descriptions of levels A and B.

When testing at rated speed is not practical, test speed shall not be less than 80% nor more than 120% of the rated speed. It is permissible on pumps greater than 225 kW (300 horsepower) to test at speeds between 60% and 140% of rated speed. Results are to be adjusted to rated speed. Any greater change in speed shall be by mutual agreement.

1.6.5.2 Witnessing of tests

The purchaser or purchaser's designated representative may witness the test when requested by the pur

\ __ / chaser in the purchase order.

1.6.5.3 Acceptance levels

The pe吋Ormance test has two levels of acceptance, A and B, for the quantitative values. Acceptance level “A" is usually applied to those pumps that are manufactured for specific conditions of service. Acceptance level “B" is usually applied to those pumps that are mass produced for stock. If not specified, level A will apply.

a) In making level "A" tests, no minus tolerances or margin shall be allowed with respect to rate of f1ow, total head or efficiency at the rated or specified conditions;

b) Acceptance of the pump test results shall be judged at rated rate of flow and rpm with applicable total head and efficiency as follows:

Performance Tolerance

Acceptance level A B

\-./ Under 60 m (200 ft) o to 680 m3/h (2999 gpm)

+8%，一 o +5%，一3%


Performance Tolerance (continued)


、、自'，

I'm -HDB nunuo nunu 呵，』nu

rt、

nu

m

內W

nuhHr 6n山I

得

前mm

d1d nHnonH U6a +5%，一 o +5%，一3%

From 60 m (200 ft) to 150 m (500 ft), any f10w rate

+5%，一 o + 5%，一3%

150 m (500 ft) and over, + 3%，一 O

any f10w rate +3%，一O

Minimum efficiency at rated Tl p or Tl OA

rpm and rate of f10w

(For Level A， ηp = contract pump efficiency)

(For Level B， ηp = published, nominal efficiency)

c) Alternatively, the pump test results may be judged at rated total head and rpm versus rate of flow as follows:

Performance Tolerance


Rate of flow tolerance at rated total head

+ 10，一 0% + 5，一5%

Minimum efficiency at rated rpm and total head (亨)一 0.2

Tlp or Tl OA .

d) Examples in metric units follow for a pump rated 227 m"/h, 30.5 m, 80% efficiency, water with 1.0 specific gravity:

1) Per Para b, level A at rated rate of flow and rpm, test total head range;

30.5 x 1.08 = 33 m max;

30.5 x 1.0 = 30.5 m min;

2) Per Para b, level B at rated rate of flow and rpm, test total head range;

9

HI Centrifugal Pump Tests 一一 2000

30.5 x 1.05 = 32 m max; Examples in US units follow for a pump rated 1000 gpm, 100 ft, 80% efficiency, water with 1.0 specific ~\

30.5 x .97 = 29.6 m min; gravity:

Based on minimum efficiency = 1) Per Para b, level A at rated rate of flow and rpm, test total head range;

100/[(120/80) - .2] = 76.9%; 100 x 1.08 = 108 ft max;

Test power range = 22.8 kW min; 25.7 kW max. 100 x 1.0 = 100 ft min:

3) Per Para c, level A at rated total head and 2) Per Para b, level B at rated rate of flow and rpm. rpm, test total head range;

Test rate of flow range at rated total head: 100 x 1.05 = 105 ft max;

227 x 1.1 = 250 m3/h max; 100 x .97 = 97 ft min;

227 x 1.0 = 227 m3/h min; Based on minimum efficiency =

Test power at rated total head and rpm = 100/[(120/80) - .2] = 76.9%;

Pw Test power range = 30.6 hp min; 34.5 hp max.

(加3) Per Para c, level A at rated total head and

and: rpm.

227 x 30.5 = 23.6 kW min; /"'""叫

Test rate of flow range at rated total head: 367 × (2旦)

100 1000 x 1.1=竹 00 gpm max;

250 x 30.5 = 26 kW max: 1000 x 1.0=1000 gpm min;

(們367x 100 Test power at rated total head and rpm =

4) Per Para c, level B at rated total head and Pw

rpm. (泓)Test rate of flow range:

(1000)(100) =31.6hp m-n;

227 x 1.05 = 238 m3/h max; (396叫:2)227 x .95 = 216 m3/h min; and:

Test max power at rated total head and rpm = (11 00)(100) =34.7hp max,

238 x 30.5 = 25.7 kW; (3的0)(芯)叫76.9)

100 4) Per Para c, level B at rated total head and rpm.

Test min power at rated total head and rpm = Test rate of flow range:

216 x 30.5 = 22.4 kW; 1000 x 1.05 = 1050 gpm max; ~\

367(旦)100 1000 x .95 = 950 gpm min;

10

\、..--'

Test max power at rated total head and rpm = (1050)(100)

J 、= 34.5 hp; (76.9'\

(3960)1 一一|\. 100)

Test min power at rated total head and rpm =

(950)(100) J 、= 30 hp; (80 '\

(3960)1 一一|\.100)

5) Note that the driver horsepower required is dictated by the acceptance level specified and the tolerances.

If it is necessa叩 to dismantle a pump after the pe斤。r

mance test for the sole purpose of changing rotation or machining impellers to meet the tolerances, no re-test shall be required unless the reduction in diameter exceeds 5% of the original diameter.

1.6.5.4 Peñormance test instrumentation

1.6.5.4.1 Introduction

Test instruments shall be selected so that they can provide measurements with accuracy shown in Section 1.6.5.4 .2 at BEP. Instruments need not be calibrated specifically for each test, but are to be

、、..-/ periodically calibrated by the manufacturer or suitable pa叫y. Refer to Section 1.6.5.4.3 for suitable interval between calibrations for pe吋ormance test instruments.

、、.../

1.6.5.4.2 Fluctuation and accuracy

Acceptable f1uctuation of Accuracy of the test readings instrument as a

Actual :1:% ofthe :1:% ofthe Measurement values values

Rate offlow 2.0 1.5

Differential head 2.0 1.0

Discharge head 2.0 0.5

Suction head 2.0 0.5

lnput power 2.0 1.5

Pump speed 0.3 0.3

NOTE: Since e仟iciency itself is a derived quantity, its accu.racy may be computed from the other instrument accuracies listed in the table, applying the root mean square law. It is common practice to use the actual recorded test readings for

HI Centrifugal Pump Tests 一-2000

computation of efficiency for fulfillment of the manufacturer's guarantee and to disregard the e仟ect of instrument accuracy.

1.6.5.4.3 Suitable interval between calibration for pe吋。rmance test instruments

Measuring and test equipment and measurement standards shall be calibrated at periodic intervals as listed in Table 1.20. Intervals shall be shortened as required to ensure continued accuracy as evidenced by the results of preceding calibrations and may be lengthened only when the results of previous calibrations provide definite indications that such action will not adversely a仔ect the accuracy of the system.

1.6.5.5 Peñormance test setup

This section contains general guidelines for performance test setup, to ensure accurate and repeatable test results. See Figures 1.116 and 1.117.

The performance test may utilize, but is not limited; to, the following:

a) Facility or purchaser-furnished driver. Depending on the method used to measure pump input power, efficiency data may be required;

b) Facility or purchaser-furnished speed-change unit, if required. To accurately establish pump input power, efficiency data of speed changer may be required;

c) A suction pipe or hose from the booster pump, closed tank or open sump, properly sized for the pump being tested. The f10w into the pump is to be free from swirl and have a symmetrical velocity distribution;

Priming connection

Optional throttle valve

Suction

}Rerr1州州emsame as Figure 1.117 or 1.119

訓/ -1 ~ _ Water level variance

J Optional baffle: spacing between suction and discharge pipes is to be equal to or greater than 6 times the sum of the nominal pipe diameters. When spacing must be reduced, a baffle as shown is required

Figure 1.刊 6 - Test with suction lift

11


d) A suction pressure gauge, compound gauge or pressure transducer suitable for measuring the complete range of pressures whether positive or negative;

e) A discharge pipe or hose with a pressure breakdown (throttling) device;

f) A discharge pressure gauge or pressure transducer(s) for measuring the complete range of pressures;

Table 1.20 - Recommended instrument calibration interval3

Rate offlow Power (continued)

Quantity meter Torque bar

Weighing tanks 1 yr Calibrated motor

Volumetric tank 10 yr KW Transducer

Rate meters Wa吐-amp-volt， po此able

Venturi c Wa吐-amp-volt， permanent

Nozzle c Strain gauges

Orifice plate c Transmission gear to 375 kW (500 HP)

Weir c Transmission gears above 375 kW (500 HP)

Turbine 1 yr Speed

Magnetic flow 1 yr Tachometers

Rotometer 5 yr Eddy current drag

Propeller 1 yr Electronic

Ultrasonic 5 yr Frequency responsive devices

Pressure Vibrating reed

Bourdon tube (pressure gauge) 4mo Electronic

Manometers Not req'd Photocell

Dead weight tester 1 yr Stroboscopes

Transducers 4mo Torque meter (speed)

Digital indicator 1 yr Temperature

Power Electric

Dynamometer w/scale 6 yr Mercury

Dynamometer w/load scale 6mo

a Use instrument manufacturer's recommendation if shorter than listed above.

b Unless electrical or mechanical failure.

C Calibration is not required unless it is suspected there are critical dimensional changes.

12

1 yr

Not req'db

3 yr

1 yr

1 yr

6mo

10 yr

20 yr

3 yr

10 yr

Not req'db

10 yr

10 yr

10 yr

5 yr

1 yr

2 yr

5 yr

r--\

----~、/

戶無恥\

\、.../

HI Centrifugal Pump Tests 一- 2000

Pressure Gauge

Thermometer

Control Valve lor Throttling Suction

Dampening Valve

Pressure Gauge

Return to sump Discharge

Dampening Device

_ Flow Meter il I Located in Discharge

on Test I I 2 lJ I

D 叫e刊叫C∞伽o圳n… Ad吋IJUS剖tabl怡e Spring Loaded Back Pressure Valve or Adjustable Choke Valve

Note: Position 01 these devices may be reversed in some set ups

Figure 1.117 - Open or closed tank

g) Throttling devices may be used for the suction and discharge instruments, such as needle valves or capilla叩 tubes to dampen out the pressure pulsations;

h) A means for measuring input power to the pump shall be provided and be suitable for measuring the complete range of power;

i) A means for measuring pump speed shall be provided;

j) Test setups intended for NPSH testing shall be provided with a means for lowering the suction pressure to the pump, such as a suction throtlle valve (with optional screen or straightening vanes), variable level sump in an open system, or a closed tank with a mechanism to create a vacuum or pressure;

k) A means for measuring the temperatu陀 ofthe test liquid shall be provided;

1) The actual dimensions of the suction and discharge pipes where pressure readings are to be taken shall be determined so that proper velocity head calculations can be made;

1.6.5.6 Performance test data requirements

The following data shall be obtained prior to the test run and writlen for the record to be retained for two years (see sample data sheet on page 14):

a) Record of pump type, size and serial number;

b) To verify the liquid prope此ies ， the temperature of the liquid shall be taken before and after testing. Temperature readings should be taken more often when testing for NPSHR or high-power pumps.

c) Ambient conditions, such as temperature and barometric pressure;

d) Records of critical installation dimensions, such as tank internal dimensions, pipe internal dimensions and lengths, and liquid levels (submergence) relative to datum;

e) Record of driver data, such as type, serial number, horsepower, speed range, amperage, voltage and efficiency;

'-......./ m) Flow measuring device(s).

f) Record of auxiliary equipment, such as vibration monitors, temperature sensors, low- or highpressure monitors, leakage detectors, alarms, etc.;

13


Summary of necessary data on pumps to be tested

The following information should be furnished on pumps to be tested:

General:

1 . Owner's name 2. Plant location 3. Elevation above sea level 4. Type of service

Pump:

1. Manufactured by 2. Manufacturer's designation 3. Manu伯cturer's serial number 4. Arrangement: horiz. 一一一一 vertical5. Inlet: single doubl~ 6. Number of stages 一一一一7. Size suction: nominal

actual 8. Size discharge: nominal

actual

Intermediate transmission:

1. Manufactured by

2. Type 一一一一一3. Serial number 4. Speed ratio 5. Efficiency

Driver:

1. Manufactured by 、 2. Serial number 3. Type: motor 一一一turbine 一一 other4. Rated horsepower 5. Rated speed 一一6. Characteristics (voltage, frequency, etc.) 一一一一

7. Calibration data 8. Driver efficiency

Specifying rated conditions

The following information is necessary in specifying rated conditions:

1. Liquid pumped (water, oil , etc.)

2. Specific weight 3. Viscosity at pumping temperature 4. Temperature一5. Vapor pressure 6. Rate of flow 7. Total suction lift (hs) 8. Total suction head (hs)

14

/""""、

9. Net positive suction head required (NPSHR)

10. Total discharge head (hd)

11. Total head (H) 12. Output power (Pw) 13. Efficiency (llp) 14. Input power (Pp)

15. Speed

Test information

Test information should be listed substantially as follows:

VJ hU AU

1e as ts sye 胎一

b

納

悶-吋

w

eeht 、，

-Ttququ

E

什

aee

閒叭D7T

n1234 e G

Rate of flow:

1. Method of measurement

-G

2. Meter-make and serial number 3. Calibration data

/'“悟、、

Head:

1. Suction gauge-make and serial number

2. Calibration data

3. Discharge gauge-make and serial number

4. Calibration data

Power:


2. Make and serial number of instrument

3. Calibration data

Speed:


2. Make and serial number of instrument

/串門

3. Calibration data

\、四旬~/

g) Instrument calibration records and correction factors in accordance with instrumentation calibration section;

h) Identity and authority level of test personnel in charge of tests;

i) The actual dimension of the areas where pressure readings are to be taken shall be determined so that proper velocity head corrections can be made.

1.6.5.7 Peñormance test records

Complete written or computer records shall be kept of all information relevant to a test and kept on file , available to the purchaser by the test facility, for two years.

The manufacturer's serial number, type and size, or other means of identification of each pump and driver (if calibrated and used to obtain the pump's efficiency) involved in the test shall be recorded to avoid mistakes in identity.

While these records apply to the complete unit, including the driver, the standard itself applies only to tests ofthe pump.

\ j 1.6.5.8 Calculations

1.6.5.8.1 Calculation of total suction head (hs)

h~ = h_ +h.. +Z~ ò:1 S • s

1.6.5.8.2 Calculation of total discharge head (hd)

h .J = h_ +h.. +Z.J d "gd. "vd . ~d

1.6.5.8.3 Calculation of total head (H)

H = hd-hs

For definition of terms and algebraic summation of the parts, see Section 1.6.3.12.

1.6.5.8.4 Calculation of input power

The input power (Po), when measured by transmission dynamometer, is calculated from the following formula:

(Met川nits): 月=計布\-....../


2nLWn n 干(US units): P n :"~~';:'~' ~

p 33,000 5250

Where:

L = Length of lever arm in m (的;

W = Net force in N (Ib);

n = Pump speed in rpm;

,. = Torque in N.m (pound-feet).

The electrical horsepower input to an electric motor is given by:

(Metric) P mot = kW

w一明

bn一-J

-nu --o m p s nH U S U

Where:

kW = Electrical input power in kilowatts.

The input power to a pump driven by an electric motor IS:

P- = P…×旦旦tp mUL 100

1.6.5.8.5 Calculation of output power

The liquid horsepower (Pw) is computed by the foll.owing formula:

的 Metric units:

P=QH(S) w 366

b) US units:

P... = W

df 的Md

haω-

hdzw一

α.卅一

×

-m MU

文u

fm.-丸

lum的一:

&山

m一

nE

.'-心da

一

μ仰P

一

When the specific weight of the liquid is 62.3 pounds per cubic foot, which is the value for water at a standard temperature of 680 F, then:

15

/-\ In order to maintain hydraulic similarity with the field operation, the following relationships are used for determining the head, rate of flow, power and NPSHR at the rated point. These relationships which follow definite rules are known as the affinity laws. The power relationship is based on the criteria that the efficiency stays constant with change in speed.


If the pump is handling a liquid with different specific weight, or water at a temperature resulting in a specific weight per cubic foot other than 62.3 pounds, the above formula must be corrected so that:

P... = 旦旦w 3960

三= (~:r.5 = (::f333 = (泛注~f50 1

O2

P-QH(S) w 3960

Where: If pump output is measured in pounds per square inch, the formula for output power, regardless of the specific weight of the liquid, becomes: rate of flow on test; -0 1

rate of flow on installation; -O2 P=QAP w 1710

speed on test in rpm; -n1

speed on installation in rpm; 一-n2

Calculation of efficiency

The pump efficiency expressed in percent is calculated by:

1.6.5.8.6

head on test;

head on installation;

-

--

叫

H2 η = ~wx 100 p P

p /月四\

/

power on test; -P1

The overall efficiency of a motor-driven unit expressed in percent is calculated by:

power on installation; -P2

NPSHR1 = NPSH on test; f P\ ηOA=(FL)1OO or;ηOA =ηpX站t\ mot/ NPSHR2 = NPSH on installation.

正工ω且Z

Figure 1.118 - Pump pe斤。rmance (all data is corrected to rated speed)

之|間!ET|d SPEED-RPM

、 Denotes head- rate olllow

』\kfor w| hich pump was sold

戶均h\

τz g 3 EmclemIY L..----""" 戶「弋、\

\

是UET 」志• ñ、 / v

/ Power(s= 1 日r)r 」戶，

已治~ z EE L

/ 1----"" v 」戶，

一17豆 / NPSHR -L..----"""

1/ I I

Plotting performance test results

The total head, efficiency and power input are usually plotted as ordinates on the same sheet with rate of flow as the abscissa, as shown on Figure 1.118.

1.6.5.8.7

Performance test at other than rated 1.6.5.8.8 speed

Test of a full-sized pump at reduced 1.6.5.8.8.1 speed

Rate offlow

In tests at reduced speed, the relative power loss in bearing and stuffing-box friction may be increased, an effect which may be appreciable in small pumps. The hydraulic friction losses may be relatively increased when the Reynolds number for the water passages is reduced , an e仟ect which may be appreciable in small pumps of low specific speed. Therefore, these factors must be considered in determining an acceptable test speed.

16

\、、

Sealless pumps incur significant eddy current losses which are affected by speed. Impeller input power varies approximately with the cube of rpm as they do in conventionally sealed pumps. Eddy current losses are propo付ional to rpm squared. Therefore the following power correction for speed is made:

P2 = (P 1 - EC1 )(n2/n1)3 + EC1 (n2/nd;

P1 = Power on test in kW (bhp);

P2 = Power on installation in kW (bhp);

EC1 = Eddy current losses on test in kW (bhp).

Eddy current losses, EC1, are normally measured by manufacturers during development studies. Values from these tests may be used in lieu of measurements during the contractural performance test.

1.6.5.8.8.2 Peñormance test of full-sized pumps at increased speed

Under unusual circumstances, it may be desirable to carry out tests at higher speeds than specified for the installation. This may be due to the limitations of available prime movers or correct electrical frequency. In this case, if such tests do not exceed safe operating

\--..-/ limits of the pump, all of the above considerations continue to apply.

1.6.5.8.8.3 Peñormance test correction to rated speed

For purposes of plotting, the rate of flow, head and power shall be corrected from the test values at test speed to the rated speed of the pump. The corrections are made as follows:

Ra悟 of flow: O2 = [去]Q1

rn司l2Head: H'l = I 二 I H.

色 Ln 1 J ﹒

rn'll3 Input power: P2 = I 前 I P1

Example (Metric): A pump for 90.8 m3/h , 68.5 meters, total head and 8 m NPSHA running at 3550 rpm is to be tested at 2950 rpm. What head, rate of flow and NPSHA should be used in the factory test?

、、 )


Applying the relationships given above, the head per stage to be used in the factory test is:

m 門J

7, A『一

一

月4「III-l

」

nu-nU FO=b Q三Fb

呵，ιZJ

「Ill-L

5 0o no --門4「

lIlli--

叫一~

「Il--

」

qJh

H 一-

H

The rate of flow to be used in the factory test is:

0 1 =叫~:] =ω8[誨] = 75.5枷

slnce:

一 n2(02)0.5 3550(90.8)。 5=1420叫 H歹5"" - 68.50.75

then,

-nT(Q1)。 5=2950(75.5)05=1420叫 H歹75 47.30

γhe NPSH to be used in the factory test is:

NP叫 = NPSH2 [之r = 8[誨r = 5.5 m

Example (US Units): A pump for 400 gpm, 225 feet total head and 26.1 ft NPSHA running at 3550 rpm is to be tested at 2950 rpm. What head, rate of flow and NPSHA should be used in the factory test?

Applying the relationships given above, the head per stage to be used in the factory test is:

叫=叫去了=叫:第r = 155 位

The rate of flow to be used in the factory test is:

0 1 = 02[之] = 4叫::這] = 332

slnce:

N-n2(Q2)。 5-3550(400)0.5=1220叫一可.75 一部0.75

17


then

N-n1(Q1)。 5z2950(332)0.5=1220叫 -1TT 叫0.75

The NPSH to be used in the factory test is:

叫1=NPm2[2]2=261[諮r = 18ft

This will keep the specific speeds the same in the facto叩 test as in the field installation.

1.6.5.8.9 Performance test correction for temperature variations

Variations in the temperature of the liquid pumped cause changes in the specific weight and viscosity, with resultant changes in the pe斤。rmance of the pump.

Any reduction in specific weight, as caused by an increase in temperature, results in a directly proportional reduction in output and input power; therefore, the efficiency is not changed.

Reduced viscosity of water at increased temperature will have an influence on efficiency. For pumps in the lower range of specific speed typically below 1750 (1500), such as high pressu舟， multi-stage boiler feed pumps and large, single-stage hot water circulating pumps, reduced viscosity will:

increase the internal leakage losses;

reduce disc friction losses;

reduce hydraulic skin friction or flow losses.

The net e仟'ect of a reduction in viscosity due to higher temperature will depend on specific speed and on the design details of the pump. Where substantiating data are availab峙， performance data from a cold water test may be adjusted to hot water operating conditions on the basis of the following formula:

t = 1 一 (1 叫)(如x

Where:

η= Efficiency at test temperature, decimal value;

18

llot = Efficiency at operating temperature, decimal value; \

、

Vot = Kinemati<? viscosity at operating temperatu悶， mm句s;

的= Kinematic viscosity at test temperature, mm2/s;

x = Exponent to be established by manufacturer's data (probably in the range of 0.01 toO.1).

Example: (Metric) Typical efficiency adjustment for increased temperature. A test on water at 37.80 C resulted in an efficiency of 80%. What will be the probable efficiency at 1770 C?

IV _"\X

η ot = 1 一 (1ηt)l ~L)

“ •• nu \ll/ Fhd只U

85

,

4

自一『'，

.. '、/

/干Lm

o-8 nO/1

、

、BF

-n/-4tnu

'，1

、'，

.. 、

一一

4司••

a司••

一一一一

tt oo nH.

吶UE

llot = .826 = 82.6%

Example: (US units) Typical efficiency adjustment for increased temperature. A test on water at 1000 F resulted in an efficiency of 80%. What will be the probable efficiency at 3500 F?

IV_"\X η ot = 1 一 (1 叫)1如

r.00000185 ,\0.1 川= 1 一 (1 一 .80)1 一一一一一 l

or .- -'\. .0000076 )

llot = 1 一 (0.2)(.868) ,

llot = .826 = 82.6%

/-\

1.6.5.8.10 Performance test correction for specific weight variations

If the test is run with a liquid of different specific weight from that of the field installation, there will be a revision in required input power which will be determined as follows:

y2 (Pn)" = (Pn ) , X 一P'2 ,. P'1 "y1

There is no change in e仔iciency./"'四""

\

刊、~'

Sealless centrifugal pumps incur significant eddy current losses which are not affected by specific weight variations. Power correction for installation specific weight different from test specific weight is made as follows:

“自﹒

C E + 句ι-4l

γ4γs

、、.，'，

祠，.

C E P J'，、一

一吋/h

p

Where:

門= Power for a specific weight on test in kW (bhp);

P2 = Power for a specific weight on installation in kW (bhp);

EC1 = Eddy current losses on test in kW (bhp).

1.6.5.8.11 Performance test correction for viscosity variations

、 / )

Viscosity has a very definite effect on the operating conditions of the pump with respect to head, rate of flow, efficiency and input power. Pumps for viscous service, which are tested with water, will require corrections to approximate the performance with the viscous liquid. (See ANSI/HI 1.3-2000, Centrifugal Pump Operation. )

Thermometer Dampening Valve

Control Valve for Throttling Suction

Pressure Gauge


1.6.5.9 Performance test correction for solids in suspenslon

Solids in suspension affect the operating performance of the pump in varying degrees, depending on the percentage and nature of the solids. No definite corrections can be recommended.

1.6.5.10 Report of pe吋。rmance test

AII parties to the test shall be furnished a copy of the pe斤。rmance curve at constant speed.

1.6.6 Net positive suction head required test (optional)

1.6.6.1 NPSHR test 。叫ective

To determine the NPSH required (NPSHR) by the pump.

1.6.6.2 NPSHR test arrangements

Three typical arrangements are shown for determining the NPSHR characteristics of pumps.

In the first arrangement, Figure 1.119, the pump is supplied from a constant level supply through a throttle valve which is followed bya section of pipe containing straightening vanes or a minimum of seven diameters

Pressure Gauge

Dampening Device

Return to sump Discharge

\、包呵../

Note: Position of these devices may be reversed in some setups.

Figure 1.119 - Suppression type NPSH test with constant level sump

19


of straight pipe to straighten flow. This arrangement dissipates the turbulence produced by the throttle valve and makes possible an accurate reading of suction pressure at the pump inlet.

This simple arrangement usually is satisfactory for NPSHR greater than 3 meters (10 feet), although the turbulence at the throttle valve tends to accelerate the release of dissolved air or gas from the liquid which takes place as the pressure on the liquid is reduced. A test made with this arrangement usually indicates higher NPSHR than that which can be expected with deaerated liquid.

In the second arrangement, Figure 1.120, the pump is supplied from a sump in which the liquid level can be varied to establish the desired NPSH. This arrangement provides an actual suction lift and hence more nearly duplicates operating conditions of pumps on water service. Care should be taken to prevent vortexing as liquid level is varied. The priming connection should be installed above the eye of the impeller either in the suction pipe or on the pump.

In the third arrangement, Figure 1.121 , the pump is supplied from a closed tank in which the level is held constant and the NPSHA is adjusted by varying the air or gas pressure over the liquid, by varying the temperature of the liquid , or by va叩ing both.

This third arrangement tends to strip the liquid of dissolved air or gas. It gives a more accurate measurement of the pump pe斤ormance uninfluenced by the

Suction

Priming connection

)R…d…ystem same as Figure 1.117 or 1.119

間恰

OHue -huov h-M叫

ctI

剖 r i ~ ___ Water level variance

Optional baffle: spacing belween suclion and discharge pipes is 10 be equal to or grealer Ihan 6 limes Ihe sum of Ihe nominal pipe diamelers. When spacing musl be reduced, a baffle as shown is required.

Figure 1.120 - Level control NPSH test with deep sump supply

20

release of air or gas. This arrangement more nearly duplicates service conditions where a pump takes its supply from a closed vessel at or near its vapor pressure. It is also acceptable to tést with a closed loop without the closed tank on the suction side.

In each of these arrangements, water shall be used as the test liquid. Aeration shall be minimized by taking the following precautions:

submerged return lines;

reservoir sized for long retention time to allow air to escape;

inlet line properly located to prevent vortexing;

reservoir bafftes to isolate inlet from return line;

tight pipe joints and stuffing boxes to guard against air leakage into the system.

1.6.6.3 NPSHR test procedure

The cavitation characteristics of a pump can be determined by one of the following procedures:

/"\ Using one of the test arrangements shown, the pump is run at constant rate of flow and speed with the suction condition varied to produce cavitation. Plots of head shall be made for various NPSH values.

Gas Pressure

Heat Exchanger

Flow Distributor

-------一一

------

Heating or Cooling Coil

Suction

•

。ischarge

/叩九

Figure 1.121 - Vacuum and/or heat control NPSH test with closed loop

HI Centrifugal Pump Tests 一- 2000

NPSHR characteristics. The relationship between model results and predicted full-size characteristics is described in Section 1.6.13.

Accurate determination of the cavitation point requires careful control of all factors which influence the operation of the pump. A minimum of five test points bracketing the point of change shall be taken, and the data plo位ed to determine when the performance breaks away from that with excess NPSHA. Any change in pe斤'ormance， either a deficiency at a given rate of flow, or change in sound or vibration, may be an indication of cavitation. But because of the difficulty in detérmining just when the change starts, a drop in head of 3%, which is the standard value in determining NPSHR, is accepted as evidence that cavitation is present. The 3% head drop is based on the first stage head for multi-stage pumps.

As NPSHA is reduced , a point is reached where the curves break away from a straight-line trend , indicat

\/ ing a condition under which the pe斤'ormance of the 一 pump may be impaired. The degree of impairment will

depend upon the specific speed, size and service of the pump. Figure 1.122 shows results typical of a test for NPSH at flow rates both greater and less than normal. The 3% drop in head is the standard to determine NPSHR.

Another technique for determining the NPSH characteristics is to hold the speed and suction head (hs) constant and to va叩 the rate of flow. For any given suction head, the pump head may be plotted against rate of flow. A series of such tests will result in a family of curves, as shown in Figure 1.123. Where the curve for any suction head (hs) breaks away from the envelope by 3%, NPSHR is established.

The NPSHA value required to properly establish the non-cavitating performance of a pump should be determined from prior full-scale or model tests of the specific pump in question. If no such prior test results are available, a recommended NPSHA value of twice the predicted NPSHR, for rated flow rates greater than 85% of the best efficiency point, or an NPSHA value of at least two and a half times the NPSHR, for rated flow rates below 85% of the best efficiency point, is recommended for maximum assurance. It should be noted that the average pump will give full pe吋'ormance at NPSHA values only 1.3 times the NPSHR value at flow rates above 85% of the best efficiency point and 1.7 times the NPSHR value at flow rates below 85% of the best efficiency point. Accordingly, the test performed at constant rate of flow, as shown in Figure 1.124, should begin with the non-cavitating pe斤ormance NPSHA value established above, or greater.

When it is impractical to conduct a test to the above criteria on large pumps due to size, rate of flow or facility NPSHA, a model test may be used to determine

O2 - 100% cap.

0 3

NPSHR values \11 Q

旬的ω立-cvo←

、\、呵_/

When testing with water, an accurate temperature measurement usually is sufficient to establish the vapor pressure, but the degree of aeration of the water may have a considerable influence on performance. Consistent results are more readily obtained when the water is deaerated.

NPSHA

Figure constan司t

Cases may arise in which the limitations of the factory test facilities may preclude the securing of sufficient NPSHA to produce the installation NPSHA. In such cases, the NPSHR can be obtained by an increase in the pump speed with a corresponding increase in pumping head and flow rate instead of by a reduction in NPSH available:

NPSHR values

3% reduction in total head

ro 』HA-T

hH

-qd 』

H門，“

』H

| 1

.hH

3coz-cv。←

a} Correction to specified speed for net positive suction head (NPS的:

21

Figure 1.123 - NPSH test with suction head held constant

Rate of flow

\-/


H CU P N qJ』

、、BI--F/

何一川、外

/tIEI\

「】

=叭叮

dr

!n-nH fZ/llk s=

rr

門，h

NQ

Where:

NPSH1 = Net positive suction head at test speed;

NPSH2 = Net positive suction head at specified speed;

n1 = Test speed in rpm;

n2 = Specified speed in rpm;

01 = Test rate of flow;

02 = Rate of flow at specified speed;

b) NPSH - Experimental deviation from the square law.

The affinity relationships define the manner in which head, rate of flow, input power, and NPSHR vary in a centrifugal or axial flow pump with respect to speed changes. If a pump operates at or near its cavitation limit. other factors also have an e仟éct， and the limiting NPSHR value may vary other than as the square of the speed. Some of these factors are: thermodynamic e仟ect on the vapor pressure of the liquid, change in surface tension , and test differences due to the relative air content of the liquid.

3cω工

.. 3% At rates of flow 85%

干「ι | α叫吋叫l怡協…e倡s

1N、\lPSHR _ 1_ 2.5 x N、\lPSHR

, 3%

「寸2xNP…S訟卸棚H間4吶RJ[ ;詣5謊諒1§7正當古丘缸缸;y W

NPSHA þ

NPSH test at constant rate of flow Recommended NPSHA range for NPSHR test when no previous data on pumps full performance is available.

Figure 1.124 - NPSH test with flow rate held constant

22

If the manufacturer can demonstrate that, with a given pump under pa此icular conditions, an expo- ./'-\ nent different than the square of the speed exists, such exponent may be recognized and used accordingly.

1.6.6.4 NPSHR test suction conditions

The total suction head is to be determined as specified in Section 1.6.3.12 .4.

The NPSHA on the test stand shall exceed the NPSHR of the pump with sufficient margin throughout the operating range to ensure that it will have no effect on the pump performance. See Section 1.6.3.12.10 for a description of NPSHA.

For pumps in free-surface systems, the approach must be free of obstructions. The flow towards the pumps must be uniform and free of eddies and vortices.

Intake structures should be designed as described in the ANSI/HI 9.8-1998 , Pump Intake Design.

1.6.6.5 NPSHR test records

Complete written or computer records of all data relevant to the NPSHR tests shall be kept by the test facility and available to the purchaser for a minimum of two years (see sample data sheet on page 14).

---點\

This information should include:

a) Specified NPSHR and NPSHA;

b) Height of suction gauge, above or below the datum line;

c) Inside diameter of pipe at location of suction pressure tap;

d) Observed data (each run);

- water temperature;

- suction pressure;

- shaft speed;

- discharge pressure;

- rate of flow. /叩枷叭

的 Type of 悟st setup;

叫﹒

/ ./

f) Type of flow meter and calibration;

g) Type, number and calibration of pressure gauges;

h) Note any abnormal observation (noise, vibration, etc.);

i) Identification of materials at liquid end of pump;

j) Type and serial number of pump and driver;

k) Date of test;

1) Identity of personnel in charge.

1.6.6.6 Rep。吋 of NPSHR test

AII parties to the test shall be furnished a copy of the NPSHR curve or curves as described in Section 1.6.6.3.

1.6.7 Mechanical test (optional)

1.6.7.1 Mechanical test objective

To demonstrate the satisfactory mechanical operation of a pump, at the rated conditions, including: vibration levels; lack of leakage from shaft seals, gaskets, and

w\~. lubricated areas; and free running operation of rotating pa巾. When specified, bearing temperature stabilization will be recorded.

\---/

These tests do not apply to submersible pumps as described in ANSI/HI 1.1-1.2-2000 Figures 1.7 and 1.8.

References to shaft seal do not apply to sealless pumps.

1.6.7.2 Mechanical test setup

The test setup shall conform to the requirements of Section 1.6.5.5 where applicable, and the test liquid shall be clear water. In addition. instrumentation shall be added to measure the following:

a) Vibration at the pump bearing housing, in two directions perpendicular to the shaft plus the axial direction.

b) Temperature of both bearings or bearing housings.

c) Leakage from mechanical seals, gaskets, and bearing lubricant. Visual observation is sufficient for allleakage.


的 Oil temperature, when oil sump is used.

1.6.7.3 Mechanical test operating conditions

The mechanical test shall be conducted under the following operating conditions:

a) Shaft speed - as required to meet rated conditions as specified in the customer's order. Facility 60 or 50 her位 speeds may be used when customers hertz are not available, or as agreed to by customer.

b) Rate of flow - the rated rate of flow for which the pump is sold , or as adjusted to a speed other than contract by Section 1.6.5.8.8.

c) Suction pressure - as available from the test facility.

d) Liquid temperature - at ambient condition.

e) Ambient air temperature.

1.6.7.4 Mechanical test instrumentation

1.6.7.4.1 Vibration

Vibration instruments can be either hand held or rigidly attached to the pump. The sensor(s) shall be velocity type designed to read the nominal RMS velocity without filtering to specific vibration frequencies. Readings can be taken manually or with recording instruments.

1.6.7.4.2 Temperature

Temperature instruments can be any recognized temperature sensor such as pyrometers, thermometers, thermocouples and the like. They shall be capable of measuring the metal temperature on the outside of the housing of both bearings, and may be hand held or rigidly attached to the bearing housing. The top center over the bearing is usually the location of the highest temperature. Where temperature sensors are built into the pump, they shall be used instead of sensors on the bearing housing. If built-in , they must be at a location where temperature is of interest.

1.6.7.5 Mechanical test procedure

The pump rate of flow and suction pressure shall be set per Section 1.6.7.3. The pump shall be operated for a minimum of 10 minutes, and the following observations made and data recorded:

的 Leakage from shaft seals, gaskets, mechanical seal piping, and bearing housing(s).

23


b) Vibration level at both inboard and outboard bearings, in two directions perpendicular to the shaft plus the axial direction. Only the nominal RMS velocity values need be recorded. Refer to the latest HI Standard for acceptable values.

c) Bearing temperatures at both inboard and outboard bearings shall be recorded. When specified , the pump shall be operated until the bearing temperature stabilizes. See ANSI/HI 1.4-2000, Centrifugal Pumps, Section 1.4.5.2.3, for the temperature stabilization procedure.

d) Rubbing of rotating parts shall be checked for by listening for unusual or excessive noise, and observing the coast down of the pump when power is cut off. Torque readings or other changes in similar instrument readings can also indicate rubbing.

的Liquid temperature and ambient air temperature shall be taken manually or with recording instruments.

1.6.7.6 Mechanical test acceptance levels

The mechanical performance is considered acceptable when each of the following is achieved:

a) Vibration levels on both bearings in any direction do not exceed the allowable limits specified in or as specified on the order document.

b) Temperature of both bearings' housing surface does not exceed the pump manufacturer's standard for the product as established prior to test.

c) Mechanical seals may have an initial small leakage, but shall have no visible leakage when running at test operating conditions for a minimum of 10 minutes. When shut down, there shall be no visible leakage from seals for five minutes with the test suction pressure applied. The purpose of this test is to ensure that the entire seal (cartridge) has been properly installed.

24

Soft packing shall have no more than 12 drops per minute leakage for a 25-mm (1-inch) shaft up to 3500 rpm. For larger shafts or higher test speeds and pressures, allowable leakage shall be increased proportionately with shaft diameter speed and pressure or as agreed to by the purchaser.

There shall be no visible leakage through pressure containment parts, gaskets, seal recirculation

piping, bearing housing, etc. Minor leakage at pump suction and discharge flanges shall not be cause for rejection since these joints are disconnected and reconnected in the field.

d) Rubbing of rotating parts shall not be apparent from excessive noise during operation nor abrupt stopping of the pump when power is cut off.

1.6.7.7 Mechanical test records

The following data shall be recorded in either written or computer form and kept on file, available to the purchaser by the test facility, for two years.

的 The manufacturer's serial number, pump type and size, or other means of identification of the pump.

b) Vibration levels on both bearings in two directions perpendicular to the shaft plus the axial direction.

c) Temperature at both bearings.

d) Ambient air temperature.

e) Leakage from the pump as observed at the following:

- Pump pressure containment components

- Pump gaskets

一 Mechanical seal piping

一 Mechanical seal(s) or packing

- Bearing housing(s)

f) Free-running rotating parts

g) Date of test

h) Name of test technician

1.6.8 Priming time test

Priming tests should only !Je conducted on pumps designed for this application.

1.6.8.1 Priming time testing of self-priming pumps

In addition to the standard performance tests, as out-

/'''''\

~\

lined in preceding paragraphs, it may be desirable to /'拍片

test self-priming pumps to determine the priming time. For this test, the suction line shall be substantially the

、/J

『

\-/

、、、咱也./

same as that shown in Figure 1.125. Static lift between the eye of the impeller and the liquid level shall not be less than 3 meters (10 feet). No check or foot valve shall be installed in the suction piping.

In making this test, proceed as follows:

Start the unit: The priming time then shall be the total elapsed time between starting the unit and the time required to obtain a steady discharge gauge reading, or full flow through the discharge nozzle. During this phase of the test, the discharge pipe must be vented if the priming system is the recirculating type. This will prevent a back pressure from being developed as the result of the accumulation of gas. If the unit is equipped with a priming pump of the separate type, it will be necessa叩 for the discharge pipe to be sealed with a column of water that will prevent air being drawn from the discharge side of the unit.

1.6.8.2 Priming time conversion factor

If a suction pipe is used which is different in size than the pump suction size, it is necessary to compute the performance for the normal size of pipe.

Use the following equation:

True priming time =

Measured p州句 timex (eump suction s凶ì2" actual pipe size )

D = DIAMETER OF PIPE

Figure 1.125 - Suction line for static lift test


1.6.8.3 Determination of maximum developed vacuum by means of dry vacuum test

The test procedure is:

With the unit in operation and delivering full flow, close gate valve in the suction line.

The reading on the vacuum gauge will then be the maximum developed vacuum.

The gate valve shall be located on the pump flange so maximum vacuum capability can be credited to the pump.

1.6.9 Measurement of rate of flow

1.6.9.1 Introduction

Any flow measuring system may be used for measuring pump rate of flow. However, it must be installed so that the entire flow passing through the pump also passes through the instrument section so that the instrument can measure rate of flow with an accuracy of :t 1.5% at BEP.

Rate of f10w instruments are classified into two functional groups. One group primarily measures batch quantity; the other primarily measures rate of flow.

1.6.9.2 Rate of flow measurement by weight

Measurement of rate of flow by weight depends upon the accuracy of the scales used and the accuracy of the measurement of time. A certification of scales shall become pa付 of the test record , or in the absence of certification, the scales shall be calibrated with standard weights before or after the test. Time interval for the collection period shall be measured to an accuracy of one-quarter of 1 %.

1.6.9.3 Rate of flow measurement by volume

Measurement of rate of flow by volume is done by measuring the change in volume of a tank or reservoir during a measured period of time. The tank or reservoir can be located on the inlet or discharge side of the pump, and all flow into or out of the tank or reservoir must pass through the pump.

In establishing reservoir volume by linear measurements, considerations shall be given to the geometric regularity (flatness, parallelism, roundness, etc.) of the reservoir surfaces, dimensional changes due to

25


thermal expansion or contraction, or deflection resulting from hydrostatic pressure of the liquid.

Liquid levels shall be measured by means such as hook gauges, floats and vertical or inclined gauge glasses.

In some locations and under some circumstances, evaporation and loss of liquid by spray may be significant and may be greater than the effects of thermal expansion or contraction. Allowance for such loss must be made, or the loss prevented.

1.6.9.4 Rate of flow measurement by head type rate meters

Measurement of rate of flow by head meters is done by introducing a reduced area in the flow stream which results in a reduction in gauge head as the velocity is increased. The gauge head di仟érential is measured and used to determine the rate of flow. The meters discussed in Sections 1.6.9.4.1. 1.6.9.4.2 and 1.6.9.4.3 use this principle.

Meters falling within this classification and acceptable for rate of f10w determination under this standard , when used as prescribed herein, are venturis, nozzles and orifice plates.

For any such meter, compliance with this standard requires that a certified curve showing the calibration of the meter shall be obtained from the calibrating agency. This certification must state the method used in calibration and whether the meter itself was calibrated, or whether calibration was obtained from an exact duplicate.

When a flow meter is used on the discharge, it is preferable to install it in the high pressure section between the pump and the pressure breakdown valve. If the working pressure of the meter is lower than the pump discharge pressure at shut off, it may be installed downstream of the pressure breakdown valve, with a back pressure valve located downstream of the flow meter to ensure that the pressure will stay above vapor pressure during operation and be free of cavitation in the high-velocity section of the meter.

These precautions are stipulated to ensure uniform flow velocity within :t 20% at the meter inlet and stable flow at the downstream pressure taps. If there is a question as to whether or not uniform flow has been obtained, it shall be checked by a velocity head traverse of the pipe immediately preceding the meter

26

to ensure symmetrical velocity distribution within the pipe. ./"""\l

The pipe for one diameter preceding the upstream pressure taps shall be free from tubercles or other surface imperfections which would establish a local disturbance in line with these openings. The pressure tap opening shall be flush with the interior of the pipe or meter element as appropriate and shall be free of burrs (see Figures 1.126 and 1.127).

1.6.9.4.1 Rate of flow measurement by venturi meter

To ensure accurate results in the measurement of f10w rates with venturi meters, certain minimum lengths of straight pipe are required upstream of the meter. Table 1.21 shows these minimum lengths, expressed in terms of pipe diameters.

Nipple conneCls here

Approx. ~ rad

Figure 1.126 - Pressure tap opening

Appmx? 問

Figure 1.127 - Welded-on pressure tap opening

~\

/卅間h\l


Table 1.21 - Straight pipe required following any fitting before venturi meter in diameters of pipe

\J/

、、、、--/

Meter ratio ß (throat to inlet diameter)

One standard short radius elbow

Two elbows in same plane

Two elbows in planes at 90 degrees and with straightening vanes

Standard C. 1. flanged reducer

Standard C. 1. flanged increaser

Globe valve - with straightening vanes

Gate valve 一 0.20pen

Gate valve - 0.5 open

Gate valve - full open

1.6.9.4.2 Rate of flow measurement by nozzles

To ensure accurate results in the measurement of rate of flow with nozzle type meters, a length of straight pipe is required preceding and following the nozzle. Tables 1.22 and 1.23 show the length of straight pipe required.

NOTE: A centrifugal pump discharging directly into a venturi meter should have at least 10 diameters of straight pipe between it and the meter.

1.6.9.4.3 Rate of flow measurement by thin square-edged orifice plate

Whenever possible, the orifice plate should be calibrated in place in the piping system by weight or volume. When this is not possible, a certified curve showing the calibration of the orifice plate shall be obtained. This certification shall conform to requirements given in Section 1.6.9.4 and shall, in addition, indicate the exact location and size of pressure taps, which are then to be duplicated in the test installation.

To ensure accurate results in the measurement of rate of flow with orifice type meters, a length of straight pipe is required preceding and following the orifice

/~ plate. Tables 1.22 and 1.23 show the length of straight

0.4

2

2

2

2

2

2

O

0.5 0.6 0.7 0.8

2 3 4 6

3 4 6 8

3 4 5 7

5 7.5 10 13

2 3 4.5 6

4 6 9 12

4 6 9 12

3 4 6 8

0.5 2 3

pipe required , expressed in terms of equivalent pipe diameters.

1.6.9.5 Rate of flow measurement by weirs

This is done in open channel flow by allowing the liquid to cascade over a dam through a sharp crested contraction in the dam, which results in an increase in velocity at the contraction. The drop in liquid level at the contraction is measured and used. to determine rate of flow.

The rectangular sharp-crested weir with smooth vertical crest wall , complete crest contraction, free over-fall and end contraction suppressed is acceptable for rate of flow determination under this standard. It may be used for either factory or field testing.

For a detailed discussion of weirs, their construction , installation and operation, the user is referred to Fluíd Meters, Theír Theory and Applícatíon, a repo此 of the ASME Research Committee on Fluid Meters.

1.6.9.6 Rate of flow measurement by pitot tubes

A pitot tube is a double tube, one within the other. Rate of flow is measured by inserting the tube so that it points into the flow stream. The inner tube measures

27


Table 1.22 - Straight pipe required following any fitting before nozzle or orifice plate meter in diameters of pipe

Meter ratio 戶 (throat to inlet diameter) 0.2 0.3 0.4 0.5 0.6 0.7

Tee or wye within line flow 6 6 6.5 7 8.5 10.5

One elbow, branch flow thru tee or wye, or flow from 6 6 6.5 7 9 13 drum or separator

Globe valve - wide open 9 9 9.5 10.5 13 15

Gate valve - wide open 6 6 6 6 7.5 9.5

Two or more short radius elbows or bends in the same 7.5 7.5 8.5 10.5 13.5 18 plane

Two or more long radius elbows or bends in the same 6 6 6.5 8 11 16 plane

Two short radius elbows or bends in different planes 14.5 16 17.5 20.5 24.5 30

Two long radius elbows or bends in different planes 7 8 10 12 16 22

0.8

14

20.5

21

13.5

25

23

40

33

NOTE: A centrifugal pump pumping directly into a nozzle or orifice should have at least 10 diameters of straight pipe between it and the meter.

Table 1.23 - Straight pipe required following downstream pressure tap of a nozzle or orifice plate meter beforeany fitting in diameters of pipe

Meter ratio ß (throat to inlet diameter) 0.2 0.3 0.4 0.5 0.6 0.7 0.8

Gate valve - wide open O O O O O O O

Wye O O O O O O 4

Tee O O 。 O O 3.5 4

Expansion joint O O 。 O O 3.5 4

45 degree elbow O O O O 3.5 3.5 4

Long radius elbow or bend 2 2.5 2.5 3 3.5 3.5 4

Regulators, control valves, and partly throttled gate valves 6 6 6 6 6 6 6

28

/.而』片\

，/司h\

/研h\

、\、_/

、/、/、J

\、內、.../

the velocity head and gauge head of the liquid , and the other tube with holes in the outer wall measures gauge head only. The head differential is measured and used to determine velocity head which in turn determines flow rate.

Where it is impossible to employ one of the methods described above, the pitot tube is often used. When the flow conditions are steady during the time required to make a traverse that has variations less than :t 0.5%, the flow may be determined with a fair degree of accuracy.

The procedure set forth in the ANSI，判SME PTC 18-1992 Hydraulic Turbines is recommended

1.6.9.7 Other methods of flow rate measurement

When the methods of flow rate measurement described above are not applicable, there are other methods not included in this standard which may be utilized, provided the accuracy of the instrument as described in Section 1.6.5.4.2 can be demonstrated.

1.6.10 Head - measurement

The units of head and the definition of total head and its component parts are covered in Section 1.6.3.12.

1.6.10.1 Pressure tap location

1.6.10.1.1 Pressure tap location for level “A" tests

The taps shall be located in the piping a minimum of two (2) diameters of straight pipe before the suction flange and after the discharge flange. Figure 1.128 shows a single tap connection. To provide uniform velocity before the suction pressure tap, a straight pipe unvarying cross section of at least five pipe diameters

Figure 1.128 - Single tap connection


in length as a minimum shall precede the gauge tap, unless otherwise agreed to by the pump manufacturer and the purchaser.

If the pipe friction loss between the pump suction or discharge flange and the point of instrument connection exceeds 0.1 % of the pump head, adjustment shall be made to the total head. The friction factor used for the friction loss calculation shall be based on the appropriate roughness factors for the actual pipe section.

1.6.10.1.2 Pressure tap location for level “B" tests

On pumps with tangential discharge, the taps may be located at the suction and discharge flange of the pump, provided V2/2g is less than 8% of total head.

The following precautions shall be taken in forming openings for pressure-measuring instruments and for making connection:

The opening in the pipe shall be flush with and normal to the wall of the water passage.

The wall of the water passage shall be smooth and of unvarying cross section. For a distance of at least 300 mm (12 inches) preceding the opening, all tubercles and roughness shall be removed with a file or emery cloth , if necessary.

The opening shall be of a diameterfrom 3 to 6 mm (1/8 to 1/4 inch) and a length equal to twice the diameter.

The edges of the opening shall be provided with a suitable radius tangential to the wall of the water passage and shall be free of burrs or irregularities. Figures 1.126 and 1.127 show suggested arrangements of taps or orifices in conformity with the above.

Where more than one tap or orifice is required at a given measuring section, separate connections, properly valved , shall be made and separate instruments shall be provided.

When multiple openings (see Figure 1.129) are agreed upon as an alternative, they shall not be connected to a head-measuring instrument unless there will be no more than 1 % pressure variance between pressures at each opening. If pressure variance exceeds 1 %, they shall be measured separately and averaged.

AII connections or leads from the opening tap shall be free of liquid leakage. These leads shall be as short

29


and direct as possible. For the dry-tube type of leads,

suitable drain pots shall be provided and a loop shall be formed of sufficient heights to keep the pumped liquid from entering the leads. For the wet-tube type of leads, vent cocks for flushing shall be provided at any high point or loop crest to ensure that there are no leaks.

Suitable dampening devices may be used in the leads.

1.6.10.2 Head measurement by means of pressure gauges

The definitions in Section 1.6.3.12 apply to Figure 1.130 where temperature effects are negligible.

The quantities (Zd) and (Z5) are negative if the corresponding values are below the datum elevation.

-一_Vent Valve Pressure Tap

Valves (4)

Figure 1.129 一 Loop manifold connecting pressure taps

When the head(s) at the gauge connection(s) is below atmospheric pressure and the lead line is completely ?-\

filled with air, Z is then measured from datum to the corresponding gauge connection instead of the gauge centerline. The air-filled line should be drained before a reading is made in order to avoid the affect of liquid in the line.

Manometers, pressure transducers and other pres咱sure devices can be used in place of pressure gauges. However, the basic expression for total head and the placement of the instruments is the same.

1.6.竹 Power measurement

Pump input power may be determined by transmission dynamometers, torsion dynamometers, strain gauge type torque measuring devices or other sufficiently accurate measuring devices which result in measurement accuracy of :t 1.5% at the specified condition.

Readings of power shall be taken at the same time that rate of flow is measured.

When pump input power is determined by transmission dynamometers, the unload dynamometer shall be statically checked prior to the test by measuring the load reading deflection for a given torque and by taking the tare reading on the dynamometer scale at rated speed with the pump disconnected. After the test, the dynamometer's tare value shall be rechecked to ensure that no change has taken place. In the event of a change of 1 .0% of the power at BEP, the test shall be rerun. An accurate measurement of speed within :t 0.3% is essential.

/F時h\

「一 Gaugeconnectlon

Gauge connectlOn

V 主三三二二主〉

nv m HU DI

Datum

/'向h\

Figure 1.130 - Gauge connections

30

l\、-./

The use of calibrated dynamometers or motors is an acceptable method for measurement of pump input power.

Calibration of the dynamometer shall be conducted with the torsion-indicating means in place. The indicator shall be observed with a series of increasing loadings and then with a series of decreasing loadings. During the taking of readings with increasing loadings, the loading is at no time to be decreased; similarly, during the decreasing loadings, the loading shall at no time be increased. The calculation of output shall be based on the average of the increasing and decreasing loadings as determined by the calibration. If the difference in readings between increasing and decreasing loadings exceeds 1 %, the torsion dynamometer shall be deemed unsatisfactory.

Dynamometers shall not be employed for testing pumps with a maximum torque below one-quarter of the rated dynamometer torque.

When strain gauge type torque measuring devices are used to measure pump input power, they shall be calibrated annually, with their accompanying instrumentation. After the test. the readout instrumentation balance shall be rechecked to ensure that no appreciable change has taken place. In the event of a

j change of 1.0% of the power at BEP, the test shall be -- rerun.

Calibrated laboratory type electric meters and transformers shall be used to measure power input to all motors.

Calibrated electric motors are satisfactory to determine the input power to the pump shaft. The electrical input to the motor is observed and the observations are multiplied by the motor efficiency to determine input power to the pump shaft. Noncalibrated purchased , furnished or facility motors may be used when agreed upon by the purchaser.

The use of transmission dynamometers and motors that have been calibrated by acceptable methods previously covered shall be considered as giving the actual input power to the pump.

1.6.12 Speed measurement

Test speeds for centrifugal pumps may be in the range of a few hundred to thousands of revolutions per minute. Since the pump test data will be taken under

)/steady state conditIons, the maximum permisslble short-term speed fluctuation shall be no more than


0.3%. The instruments shall also be capable of measuring speed with an accuracy of :t 0.3%. The speed measuring methods described, therefore, are those which , at moderate speeds, will give a measure of the average speed over an interval of from less than one second up to two minutes, depending on the type of instrumentation.

The revolution counter and timer method, as its name implies, involves the counting of the number of revolutions over an interval of time. A major source of error is inexact synchronization of counter and timer. In cases where this is automatic (e.g. , digital tachometers), accuracy is achieved over a time interval of a few seconds. In the case where a handheld counter and stopwatch are used, the timing interval should be about two minutes. During this time the speed must be constant, and slippage of the counter on the shaft must be avoided. The stopwatch shall be periodically checked against a standard timer.

Tachometers provide a direct reading of speed averaged over a fixed time interval. Some types automatically repeat the reading process; handheld units must be reset manually. The above comments regarding uniform speed and slippage pertain here also. A tachometer shall be checked periodically against a counter and stopwatch.

Frequency responsive devices have the advantage of not requiring direct contact with the motor or pump shaft, and hence impose no additional load on the motor. The vibrating reed type is useful only when the shaft is completely inaccessible. Electronic units may be converted to read rpm directly using a shaftmounted gear and a non-contacting magnetic pickup. Since normally the line frequency (which determines the timing interval) is 60 Hz :t 0.1 %, the method is accurate to the nearest rpm, as read on a digital readout. The timing interval may be set as short as 0.1 second, thus making any speed fluctuations readily discernible.

Most stroboscopes are limited in accuracy due to unce吋ainty in the precision of the strobe frequency. The only approach suitable for pump test purposes is to use the strobe to determine motor slip under load relative to synchronous speed, using a stopwatch to time the slippage while driving the strobe at line frequency (which is known to the accuracy given above and can be determined with even greater precision for the time and location of the test).

31


1.6.13 Temperature measurement and instruments

Temperature shall be measured as close to the pump inlet as possible. The temperature measuring device shall have no effect on the measurements of pressure and flow rate.

AII temperature sensing instruments shall be properly supported and installed directly into the liquid stream. When this is not feasible. wells filled with suitable intermediate conducting materials may be used.

Temperature may be measured by etched stem, liquidin-glass thermometers, thermocouples or resistance thermometers. Thermocouples and resistance thermometers, when employed, require potentiometric instruments.

1.6.14 Model tests

1.6.14.1 Model test procedure

In many installations involving large pumps, model tests are often necessary. Even when it might be feasible to test the large unit in the factory, a model may often be tested with greater accuracy and thoroughness. By adopting a standard size of model for various pumps, comparable pe斤。rmances can be obtained. The model impeller should be not less than 300 mm (12 inches) outside diameter. The exact model-to國pro

totype ratio shall be selected by the builder. Comparisons between model tests are valid only when all dimensions of the model hydraulic passages to prototype are in accordance with model-to-prototype ratio.

Testing models in advance of final design and installation of a large pump not only provides advance assurance of performance but makes design alterations possible in time for incorporation in the prototype pump.

Not all installations lend themselves to a practical model investigation. The pumping of water carrying considerable quantities of sand or other foreign material is not readily reproduced in model operation. This standard , therefore, is limited to the pumping of clear water, free from abnormal quantities of air or solids, both in field installation and factory tests. The e仟ectsof wear and deterioration, the e仟'ects of free-surface disturbances in open channel sumps, interference between neighboring units , and peculiar problems caused by abnormal settings are covered by model sump tests.

32

The model hydraulic passages should have complete geometric similarity with the prototype, not only in the pump proper, but also in the intake and discharge conduits as specified above for tests on full-size pumps. If cavitation tests are not available, the NPSHA should be such as to give the same suction specific speed as the prototype. As previously explained , if the prototype NPSHR is known to be safely below the NPSHA, then a higher NPSHA can be used for the model tests, although it is preferable to maintain the same value.

There is danger of air separation destroying similarity relationships if the absolute pressure is reduced too low. Consequently, condensate pumps should not be modeled.

If corresponding diameters of model and prototype are D1 and D2 respectively, then the model speed n1 and model rate of flow Q1 , under the test head H1, must agree with the relationships:

之= [~~][~:r.5

and

之= [~:J[月0.5

The efficiency of the model will not, in general , be exactly equal to that of the prototype. In testing a model of reduced size, the above conditions being observed, complete hydraulic similarity may not be attained because of certain influences. For example, complete geometric similarity will not be obtained unless the relative roughness of the impeller and pump casing surfaces are the same. With the same surface texture in both model and prototype, the model efficiency will be lower than that of the larger unit. Further, it is generally not practical to model running clearances or bearing sizes. When such is the case, the model efficiency will be reduced.

When a high degree of understanding exists between manufacturer and user relative to the comparison limitations encountered going from model to prototype, thought may be given to the practicality of increasing the prototype e仟iciency on the basis of model test results. However, this should be done only by mutual agreement before the job is let, on the basis of all the available test data of a similar nature.

Numerous comparisons of prototype and model efficiencies, with consistent surface finish of models and

".-吟，腎、

\

,'.

/"也4、、

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prototypes, are necessa叩 for a given factory to establish a basis for calculating model performance to field

\, performance. This calculation can be applied conveniently according to the formula in use for turbines; namely

X 可Il--

」

見一叫

「Ill--」

4l-n/

“

啊可一吶-

ABE-a1

••

The exponent (x) is to be determined from actual data as described above.

The values for the exponent (x) have been found to vary between zero and 0.26, depending on relative surface roughness of model and prototype and other factors.

Example (Metrict A single-stage pump designed to deliver 20,000 m"/h against a head of 120 meters at 450 rpm and have an impeller diameter of 2 meters. This pump is too large for a facto叩 test and , in place of such test on the actual pump, a model is to be tested at a reduced head of 100 meters. The model impeller is to be 0.5 meters in diameter.

Determine speed and rate of flow for the above model test.

\-~ Apply the above relationships:

之= [刮目。 5

or

EU nu -alll」

叫一向

「Ill-tt」

「1，

Ill-J

吭高

FI--lL

呵，ι

n 一-

n

= (450[翻翻0.5) = 1643 rpm

zu nu 「Iliti

」

叫一同

「ti--L

q4 「BIll--

」

叫-q

FIll--l」

一-

qq

or

Ru nu 「Ili--

」

叫一同

「illL

qL 1lll」

叫-q

FiiIll-L

門，ι

Q 一-

Q

、旭、_/


= 20.000閻2[割的= 1141m3

The model pump should therefore be run at a speed of 1643 rpm delivering 1141 m3/h against a head of 100 m.

To check these results , it will be noted that the specific speed of the prototype is:

_ n( Q)0.5 _ 450(20,000)0.5 一一一一一- 戶 = 1755 s HO.75

and the specific speed of the model will be:

1643( 1141 )0.5 一= 1755

s 1000.75

Therefore, the specific speeds are the same as required.

Example (US Units): A single-stage pump designed to deliver 90,000 gpm against a head of 400 feet at 450 rpm and have an impeller diameter of 6.8 feet. This pump is too large for a factory test and, in place of such test on the actual pump, a model is to be tested at a reduced head of 320 feet. The model impeller is to be 18 inches in diameter.

Determine speed and rate of flow for the above model test.

Apply the above relationships:

Ru nu 可lIll-

」

叫一問

「llil--」

「Il--

」

見一叫

「Il--

」

一一

叫一的』

or

RU nu 可lae--

」

叫一向

「Ill-i」

「lIll---

q一叫

「III-ll」

們4

n 一-

n

m nv vt FO nJι

QU A-t

一-

5 nu 「III-l

」

nu-nu qL-nu 3-4. 「1，llL

可Ill--

QU-EU RO-「l『t.'IL

nu FO A『一

一A ••

n

FD nu ---」

叫一問

「llIII-L

弓，』

-aes--」

叫-q

「Ill-L

一-

q-q

or

33


Q1 =叫2]2[2]05

Q1 = 90， 000[蒜y[第r.5= 3920 gpm

The model pump should therefore be run at a speed of 1825 rpm delivering 3920 gpm against a head of 320 feet.

To check these results , it will be noted that the specific speed of the prototype is:

N_ = 旦旦旦5 450(90,000)0.5=1510 HO.75 4000.75

and th~ specific speed of the model will be:

1825(3920)0.5 一= 1510 s 3200.75

Therefore, the specific speeds are the same as required.

1.6.14.2 Model test at increased head

Under special and unusual circumstances, it may be desirable to carry out factory tests at higher heads than the prototype head. This, for example, may be due to the limitations of available test motors or electri-cal frequency. In this case, all of the above considerations continue to apply.

34

The choice of using a model is based on balancing the ,.,\

cost benefits of a smaller model versus the manufac- -\

turing and test accuracies.

It should be pointed out, however, that with a reducedsize model , coupled with an increase in head , the increase in speed corresponding to the head increase tends to minimize the change in Reynolds number; that is, the product of flow velocity and linear dimensions of the model tends to approach equality with the same product in the prototype. This effect tends to restore dynamic similarity in model and prototype and to approach equality of efficiencies and other performance factors. With increased head , however, the preservation of the same suction specific speed value in the model as in the prototype must still be observed , and this value will assume increased importance, requiring an increase in submergence or reduction in suction lift in the factory test.

The last mentioned requirement may result in another reason for the use of an increased head in the factory test. Cases may arise in which the limitations of the factory test setup may preclude obtaining sufficient suction lift to reproduce the prototype suction specific .speed. In such cases, the required value can be obtained by an increase in the pumping head instead of by a reduction in suction head or increase in suction lift.

~、\

/間只

f

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Appendix A

References

This appendix is not pa付 of this standard, but is presented to help the user in considering factors beyond the standard sump design.

A5ME-American 50ciety of Mechanical Engineers

Fluid Meters, Their Theory and Application ANSI/ASME PTC 18-1992, Hydrau/ic Turbines

American Society of Mechanical Engineers United Engineering Center 345 East 47th Street New York, NY 10017

35

HI Centrifugal Pump Tests Index 一- 2000

Appendix B

Index

This appendix is not part of this standard, but is presented to help the user in considering factors beyond this standard.

Note: an f. indicates a figure, and a t. indicates a table.

Affinity laws, 16 Atmospheric head, 5

BEP See Best efficiency point Best efficiency point, 1

Calibrated electric meters and transformers, 31 Capacity, 3

Datum, 3 Datum elevations, 3

horizontal units, 3, 4f. vertical double suction pumps, 3, 4f. vertical single suction pumps, 3, 4f.

Dry vacuum test, 25 Dynamometers, 30

calibration, 31

Electric driver input power, 7 Elevation head, 4 110A See Overall efficiency IIp See Pump e仔iciency

Frequency-responsive devices, 31

Gauge head, 4

h See Head H See Total head hatm See Atmospheric head hd See Total discharge head hg See Gauge head hs See Total suction head hv See Velocity head Head, 3

loop manifold connecting pressure taps, 30f. measurement, 29 measurement by means of pressure gauges, 30 pressure tap location for level A tests, 29, 29f. pressure tap location for level B tests, 29, 30f. single tap connection , 29f.

Hydrostatic test, 7 objective, 7

36

parameters, 8 procedure, 8 records, 8

Mechanical test, 23 acceptance levels, 24 instrumentation, 23 objective, 23 operating conditions, 23 procedure, 23 records, 24 setup, 23 temperature instruments, 23 vibration instruments, 23

Model tests, 32 at increased head, 34 procedure, 32

n See Speed Net positive suction head, 1 Net positive suction head available, 6 Net positive suction head required , 1, 7 Normal condition point, 1 NPSH See Net positive suction head NPSHA See also Net positive suction head available NPSHR See Net positive suction head required NPSHR test, 19

arrangements, 19, 19f. , 20f. level control with deep sump supply, 20去， 20

objective, 19 procedure, 20 with rate of flow held constant, 21 , 21 f. records, 22 repo此， 23

suction conditions, 22 with suction head held constant, 21 ， 21 正

suppression type with constant level sump, 19人 19vacuum and/or heat control with closed loop, 20人 20

Overall efficiency, 7

P See Power Pmot See Electric driver input power

.，........--':"，~、、\

~\

/冊川、

/

P p See Pump input power P w See Pump output power

\/ Performance test, 9 acceptance levels, 9 acceptance tolerances, 9 calculations, 15 calibration interval for instruments, 11 , 12t. correction for solids in suspension, 19 correction for temperature variations, 18 correction for viscosity variations, 19 correction to rated speed , 17 data requirements, 13 efficiency calculation , 16 at increased speed, 17 input power calculation , 15 instrumentation, 11 instrumentation accuracy，竹instrumentation fluctuation, 11 level A acceptance, 9 level B acceptance, 9 open or closed tank, 13f. at other than rated speed, 16 output power calculation, 15 plo吐ing results , 16, 16正records, 15 at reduced speed , 16 repo付， 19

sample data sheet, 14 \、一 setup ， 11

、\一/

for specific weight variations, 18 with suction Ii悅， 11 f. total discharge head calculation , 15 total head calculation , 15 total suction head calculation, 15 witnessing, 9

Power, 7 measurement, 30

Priming time test, 24 conversion factor, 25 determination of maximum developed vacuum by

means of dry vacuum test, 25 of self-priming pumps, 24 suction line, 24, 25f.

Pump efficiency, 7 calculation , 16

Pump input power, 7 calculation , 15 measurements, 30

Pump output power, 7 calculation , 15

Q See Rate of flow

HI Centrifugal Pump Tests Index - 2000

Rate of flow, 3 measurement by head type rate meters, 26 measurement by nozzles, 27 measurement by other methods, 29 measurement by thin square-edged orifice plate, 27 measurement by venturi meter, 26 measurement by volume, 25 measurement by weight, 25 measuring system requirements, 25 pressure tap openings, 26, 26f. straight pipe requirements associated with nozzle

meters, 27, 28t. straight pipe requirements associated with orifice

plate meters, 28t. straight pipe requirements associated with venturi

meters, 26, 27t. types, 25

Rated condition point, 1 Revolution counter and timer method, 31

Shut off, 1 SO See Shut off Specified condition point, 1 Speed , 3

measurement, 31 Strain gauge type torque measuring devices, 30, 31 Stroboscopes, 31 Subscripts, 3t. Symbols, 2t.

Tachometers, 31 Temperature

instruments, 32 measurement, 32

Terminology, 1 Tests, 1

conditions, 1 objectives, 1 scope, 1

Total discharge head , 5 calculations, 15

Total head, 5 calculation, 15 e仟ects of compressibility of liquid on, 5

Total suction head, 4 calculation , 15

Total suction li缸， 5Transmission dynamometers, 30, 31

Velocity head, 4 Volume, 3

Z See Elevation head

37

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