# SIST EN ISO 5198:2000

(Main)## Centrifugal, mixed flow and axial pumps - Code for hydraulic performance tests - Precision class (ISO 5198:1987)

## Centrifugal, mixed flow and axial pumps - Code for hydraulic performance tests - Precision class (ISO 5198:1987)

Definition of terms, quantities, ways of measuring the characteristic quantities of the precision class so as to ascertain the performance of the pump.

## Kreiselpumpen (Radial-, Halbaxial- und Axialkreiselpumpen) - Regeln für die Messung der hydraulischen Betriebsverhaltens - Präzisionsklasse (ISO 5198:1987)

## Pompes centrifuges, hélico-centrifuges et hélices - Code d'essais de fonctionnement hydraulique - Classe de précision (ISO 5198:1987)

## Centrifugal, mixed flow and axial pumps - Code for hydraulic performance tests - Precision class (ISO 5198:1987)

### General Information

### Standards Content (sample)

SLOVENSKI STANDARD

SIST EN ISO 5198:2000

01-december-2000

Centrifugal, mixed flow and axial pumps - Code for hydraulic performance tests -

Precision class (ISO 5198:1987)

Centrifugal, mixed flow and axial pumps - Code for hydraulic performance tests -

Precision class (ISO 5198:1987)

Kreiselpumpen (Radial-, Halbaxial- und Axialkreiselpumpen) - Regeln für die Messung

der hydraulischen Betriebsverhaltens - Präzisionsklasse (ISO 5198:1987)Pompes centrifuges, hélico-centrifuges et hélices - Code d'essais de fonctionnement

hydraulique - Classe de précision (ISO 5198:1987)Ta slovenski standard je istoveten z: EN ISO 5198:1998

ICS:

23.080 ýUSDONH Pumps

SIST EN ISO 5198:2000 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 5198:2000

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SIST EN ISO 5198:2000

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SIST EN ISO 5198:2000

IS0

INTERNATIONAL STANDARD

5198

First edition

1987-07-O 1

INTERNATIONAL ORGANIZATION FOR STANDARDIZATION

ORGANISATION INTERNATIONALE DE NORMALISATION

MEXflYHAPOflHAfl OPTAHM3A~klfl l-l0 CTAH~APTM3A~MM

Centrifugal, mixed flow and axial pumps - Code for

hydraulic performance tests - Precision class

Code d’essais de fonctionnement

Pompes ten trifuges, h&co-ten trifuges et hklices -

h ydraufique - Classe de prbision

Reference number

IS0 5198: 1987 (E)

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SIST EN ISO 5198:2000

Foreword

IS0 (the International Organization for Standardization) is a worldwide federation of

national standards bodies (IS0 member bodies). The work of preparing International

Standards is normally carried out through IS0 technical committees. Each memberbody interested in a subject for which a technical committee has been established has

the right to be represented on that committee. International organizations, govern-

mental and non-governmental, in liaison with ISO, also take part in the work.Draft International Standards adopted by the technical committees are circulated to

the member bodies for approval before their acceptance as International Standards by

the IS0 Council. They are approved in accordance with IS0 procedures requiring at

least 75 % approval by the member bodies voting.International Standard IS0 5198 was prepared by Technical Committee ISO/TC 115,

Pumps.

Users should note that all International Standards undergo revision from time to time

and that any reference made herein to any other International Standard implies its

latest edition, unless otherwise stated.0 International Organization for Standardization, 1987

Printed in Switzerland

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SIST EN ISO 5198:2000

IS0 5198 :I987 (E)

Contents

Page

. . . ............. I

0 Introduction. ............... ....... ....... . . .

............. 1

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

. . . ............. I

2 Field of application .......... ....... ....... . . .

. . . ............. 2

3 References. ................ ....... ....... . . .

Section one : General recommendations

4 Definitions and symbols . . . . . . . . . . . .

5 Specified duty . . . . . . . . . . . . . . . . . . . .

6 General requirements for tests . . . . . .

Section two : Measurement methods

7 Measurement of rate of flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . * . 17

8 Measurement of head. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

..................................... 389 Measurement of speed of rotation

......................................... 38

10 Measurement of power input

........ . . 41

11 Measurement of pump efficiency by the thermodynamic method

.................................................. . .

12 Cavitation tests 51

Annexes

A Estimation and analysis of uncertainties .............................. . . 57

B Comparison of test results with specified duty. ........................ . . 61

C Thermodynamic properties of water and assessment of the accuracy................ 65

of efficiency measurements by the thermodynamic method

D ................................................ 78

Other cavitation tests

E ..................................................... 80

Frictionlosses..

. . .

III

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SIST EN ISO 5198:2000

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SIST EN ISO 5198:2000

INTERNATIONAL STANDARD

IS0 5198 : 1987 (E)

Centrifugal, mixed flow and axial pumps - Code for

hydraulic performance tests - Precision class

0 Introduction This International Standard does not recommend any construc-

tional tolerance nor any global tolerance for acceptance pur-

This International Standard is the first of a set of International poses; it is devoted to specifying and describing procedure and

Standards dealing with performance tests of centrifugal, mixed methods for accurately ascertaining the performance of a pump

flow and axial pumps (in the rest of the text referred to as under the conditions in which it is tested. Contractual

“pumps”). interpretation of the test results must be the subject of a specialagreement between the parties concerned (see annex B).

It specifies precision class tests (former class A). Engineering

class I and class II tests (former classes B and C) will be the Pump performance may be greatly affected by the installation

subject of a further International Standard? conditions, and this must be especially considered when

drawing up the contract if a precision class test is to be carriedThe aims of these classes are quite different.

The precision class is mainly used for research, develop-

ment and scientific purposes in laboratories, where an

4 Scope

extremely high accuracy of measurement is important.

This International Standard specifies precision class pe rfor-

The engineering classes are generally applied for acceptance

mance tests for centrifugal, mixed flow and axial pumps.

tests.

It defines the terms and quantities that are used and specifies

In most cases, engineering class II is adequate for acceptance

general requirements for tests. It specifies ways of measuring

tests. The use of engineering class I is restricted to special

the characteristic quantities of the precision class so as

cases when there is a need to have the pump performance

to ascertain the performance of the pump and thus provide a

more precisely defined. However, there may be cases of high

basis for comparison with the performance specified in the

importance, in which even an engineering class I acceptance

contract.

test will be judged inadequate for the precision required for

defining pump performance. In these cases the use of the

The structural details of pumps and the mechanical properties

precision class may exceptionally be necessary for an accep-

of their co mponents lie outside the scope of this I

nternational

tance test.

Standard.

Attention must be paid to the fact that the accuracy required

This International Standard does not specify constructional

for a precision class test significantly increases the test costs by

tolerances, which are purely contractual.

comparison with the costs for an engineering class test.

Precision class tests may not always be practicable, even when

great effort and expense are devoted to measurements. Perfor-

2 Field of application

mance tests to precision class specifications will be required,

and are possible, only in suitable circumstances. Therefore This International Standard gives recommendations for

both the purchaser and the manufacturer shall carefully ex- hydraulic performance testing of centrifugal, mixed-flow and

amine whether the accuracy required for a precision class test axial pumps when these tests have to meet very special require-

might be achieved either on site, on the manufacturer’s testments for research, development or acceptance of industrial

bed or in a mutually agreed laboratory. It should be noted that it high-tech. pumps, or when very accurate knowledge of perfor-

may not be possible to guarantee precision class accuracy inmance characteristics is of prime importance.

advance of the tests.

This International Standard also applies to models and proto-

The purpose of this International Standard is to specify how to types whether the pumps are tested on a test bench or on site if

carry out a test with extremely high precision. installation conditions so permit.

1) At present, they are dealt with in IS0 2548 and IS0 3555.---------------------- Page: 9 ----------------------

SIST EN ISO 5198:2000

IS0 5198 : 1987 (E)

It applies IS0 3534, Statistics - Vocabulary and symbols.

either to the pu mp itself without fittings, which re-

IS0 3555, Centrifugal, mixed flow and axial pumps - Code for

quires that the pump ends are accessible; or

acceptance tests - Class B.

to the whole assembly of pump and of all or part of its

IS0 3846, Liquid flow measurement in open channels by weirs

upstream and downstream fittings, which is the case for

and flumes - Free overfall weirs of finite crest width frec-

pumps with inaccessible ends (submerged pumps, etc.).

tangular broad-crested weirs).

NOTES

IS0 3966, Measurement of fluid flow conduits -

in closed

1 Attention is drawn to the fact that nearly all industrial needs are

Velocity area method using Pitot static tubes.

covered by the codes of acceptance testing of industrial classes I

and II.

I SO 4185, Measurement of liquid flow in closed conduits -

2 Acceptance tests for site and model storage pumps are dealt with in

Weighing method.

IEC Publications 198 and 497.

IS0 4359, Liquid flow measurement in open channels - Rec-

tangular, trapezoidal and U-shaped flumes.

3 References

IS0 4360, Liquid flow measurement in open channels by weirs

IS 0 31, Quantities, units and symbols.

and flumes - Triangular profile weirs.

IS0 555, Liquid flow measurement in open channels - Dilu-

tion methods for measurement of steady flow -

IS0 4373, Measurement of liquid flow In open channels -

Water level measuring devices.

Part 1: Constan t-rate injection method.

Part 2: Integration (sudden injection) method.

IS0 5167, Measurement of fluid flow by means of orifice

plates, nozzles and venturi tubes inserted in circular cross-

Part 3: Cons tan t-ra te injection method and integration

section conduits running full.

method using radioactive tracers.

IS0 1438, Liquid flow measurement in open channels using I S 0 5168, Measurement of fluid flow - Es tima tion of uncer-

tainty of a flow-rate measurement.thin-plate weirs and venturi flumes.

IS0 1 4381 1, Water flow measurement in open channels using

I SO 7194, Measurement of fluid flow in closed conduits -

weirs and venturi flumes - Part I: Thin-plate weirs.

Velocity-area methods of flow measurement in swirling or

asymmetric flow conditions in circular ducts by means of

IS0 2186, Fluid flow in closed conduits - Connections for

current-meters or Pito t static tubes.

pressure signal transmissions between primary and secondary

elements.

IS0 8316, Measurement of liquid flow in closed conduits -

Method by collection of the liquid in a volumetric tank. l)

IS0 2548, Centrifugal, mixed flow and axial pumps - Code for

acceptance tests - Class C.

IEC Publication 34-2, Rotating electrical machines - Part 2:

Methods for determining losses and efficiency of rotating elec-

IS0 2975, Measurement of water flow in closed conduits -

trical machinery from tests (excluding machines for traction

Tracer methods -

vehicles).

Part I: General.

IEC Publication 41 , In terna tional code for the field acceptance

method using non-

Part 2: Constant injection

tests of hydraulic turbines.

radioactive tracers.

Part 3: Constant rate injection method using radioactive IEC Publication 193, International code for

model acceptancetracers. tests of hydraulic turbines.

Part 6: Transit time method using non-radioactive tracers.

IEC Publication 198, International code for the field acceptance

tests of storage pumps.

Part 7: Transit time method using radioactive tracers.

IS0 3354, Measurement of clean water flow in closed con- IEC Publication 497, International code for

acceptance- Velocity-area method using current-meters,

duits tests of storage pumps.

1) At present at the stage of draft.

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SIST EN ISO 5198:2000

IS0 5198 : 1987 (E)

Section one : General recommendations

4 Definitions and symbols or the autocorrelation function, I?,, given by the equation

t+ T4.1 Definitions

R, (t, T) = -

x(t) [x(t + T)] dt

T t

For the purposes of this International Standard, the following

definitions apply.

4.1.5 steady and unsteady process: Random process x(t)

is said to be slightly steady or steady in a general sense

when its first order statistical moment (mean ,uJ and its second

order statistical moment [variance OS, or autocorrelation func-

4.1.1 measuring system : System composed of a measuring

tion R, (t, T)] are not dependent on time t, at which the obser-

instrument, including a transducer which picks up physical in-

vation begins nor on the period of time T during which the

formation, and one or several elements in series transmitting or

observation is made.

transforming the resulting signal.

Inversely, when the statistical moments are dependent

Such a system has a response function which can be illustrated on t or

T, the physical phenomenon is said to be u nsteady.

by a gain response or a phase response curve over a frequency

range. In particular, a filtering effect appears between the

When all statistical moments of the process x(t) (beyond the

picked up physical quantity and the observed signal. This filter-

second order), which completely describe the statistical prop-

ing effect is essentially characterized by a cut frequency. In

erty of x(t), are not dependent on t and T, the process is then

most measuring systems which are used, the continuous com-

said to be strongly or strictly steady.

ponent of the signal can pass and the cut frequency is then

strongly related to the response time of the system.

NOTE - From a practical point of view and in this International Stan-

dard, only slightly steady processes are considered (first and second

order statistical moments). It should be noted that when the con-

4.1.2 measuring instrument : Instrument, forming part of a

sidered process follows a normal or Gaussian distribution law, the first

measuring system, which transforms any physical quantity

and second order statistical moments are sufficient to describe the

(pressure, speed, current, etc.) into a signal which can be statistical properties of the process completely and both concepts of

strong or slight steadiness are then equivalent.directly observed (a mercury level, a point on a dial scale, a

digital reading, etc.).

4.1.6 steady operating conditions : The operating condi-

tions are said to be steady when the different signals delivered

4.1.3 first order statistical moment: mean value of a

by the measuring systems and the physical quantities

signal: Characterization of a random process x(t) by a first

calculated from these signals have first order (mean ,u,) and

order statistical moment which generally is the mean ,uX

second order [variance oX2, or autocorrelation function R,

calculated over a period of time T given by the equation

(t, T)] statistical moments which do not depend on the time t

at which the observation begins nor on the duration T during

t+ T

which the observation is made.

x(t) dt

I-& = -

T t

NOTE - The random signal delivered by a measuring system can be

found to be steady only if the integration period T is sufficiently long.

NOTE - To calculate the mean value of a signal or physical quantity,

This point is difficult to check for one is never calculated for a sufficient

an integration period T much longer than the response time of the cor-

duration; this is why, from a practical point of view, only a steadiness

responding measuring system is usually chosen.

with a certain confidence level is defined.

To determine simultaneously the mean value of several signals of

several physical quantities corresponding to the same operating point,

the integration period T is chosen by considering the longest response 4.1.7 unsteady operating conditions : The operating condi-

time among all the measuring systems which are used.tions are said to be unsteady when the different signals

delivered by the measuring systems and the physical quantities

According to the value of the integration period T chosen to calculate

calculated from these signals have a first order (mean ,uJ or se-

the mean value of the signals, the operating conditions will be deter-

cond order [variance crz, or autocorrelation function R, (t, T)]

mined to be either steady or unsteady.

statistical moment which depends on the time t at which the

observation begins or on the period T during which the obser-

vation is made.

4.1.4 second order statistical moment: variance or

autocorrelation function : Characterization of a random pro-

NOTE - The dynamic component (see figure

1) of the picked up

cess x(t) by a second order statistical moment calculated over a

physical quantities has different origins :

time period Tand for which can be chosen either the variance

a) a random origin : turbulence, white noise of the electronic

a: expressed as :

system, etc.,

t+ T

b) a determinist origin: blade passing frequency, speed of rota-

tion in connection with the electric network frequency, flow

ax = -

[x(t) - p$dt

T t

singularities, vibration modes, etc.

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SIST EN ISO 5198:2000

IS0 5198 : 1987 (E)

Tl is an insufficiently long integration period. The mean value, X, of x as estimated from T, will vary.

T2 is a sufficiently long period.Figure 1 - Graph of the evolution of a phenomenon (supposed to be known)

It is supposed that the possible unsteadiness of the operating Then the variations of the mean value can be considered as

conditions has a frequency lower than that corresponding to thesebeing “slow” compared to fluctuations (see 4.1.8).

phenomena (less than half the lowest encountered frequency); as a

consequence, the integration period Twill not be less than twice the

period T corresponding to the lowest frequency mentioned above.

4.1 .lO readings: Visual observations allowing the recording

of the value of the signal delivered by a measuring system.

4.1.8 fluctuations: Periodic or random evolutions of a

phenomenon x(t) as a function of time, varying around a mean

Two types of readings should be considered:

value and describing a physical quantity or a signal delivered by

a measuring system.

a) the “quasi-instantaneous” reading of the signal, which

All evolutions having a period or a pseudo-period less than

is made during as short a time as possible (but not shorter

twice the integration period chosen to calculate the mean

than the response time of the measuring system

values are considered as fluctuations. Then the fluctuations

considered) ;

can be considered as being “rapid” compared to the variations

of the mean value (see 4.1.9).

NOTE - The group of “quasi-instantaneous” readings made

during the integration period Tallows the calculation of statistical

NOTE - Only fluctuations having a period or a pseudo-period higher

moments (see 4.1.3 and 4.1.4).

than twice the response time of the corresponding measuring system

can be detected.

b) the “averaging reading” of the signal which is made

over or at the end of the integration period T depending on

4.1.9 variations of the mean value (in unsteady

the measuring system, this “averaging reading” leads

Evolution of the mean value of a

operating conditions) :

directly to the mean value of the signal.

physical quantity or of signal delivered by a measuring system,

between one reading and the next, in unsteady operating con-

ditions.

4.1.11 set of readings: Group of “quasi-instantaneous”

The variations of the mean values should show a period or a readings leading to the determination of the values of the dif-

pseudo-period higher than twice the integration period Tferent signal or physical quantities characterizing an operating

chosen to calculate the mean value. point.

---------------------- Page: 12 ----------------------

SIST EN ISO 5198:2000

ISO5198:1987 (El

4.1.12 response time of a measuring instrument: Time 4.2 Quantities, symbols and units

interval between the instant when a stimulus is subjected to aspecified abrupt change and the instant when the response

Table 1 gives concepts and some of their uses in this Inter-

reaches and remains within specified limits of its final steady

national Standard, together with any associated symbols which

value.

have been allocated; it is based on IS0 31.

4.1.13 Prandtl number, Pr:

PCP The definitions, particu I arly those given for kinetic energy coef-

ficient, specific energy and NPSH may not be appropriate for

pr = --i-

completely general use in hydrodynamics, and are for the pur-

where

poses of this International Standard only.

p is the dynamic viscosity of the fluid;

A is its thermal conductivity.

Table 2 gives an alphabetical list of symbols used, and table 3

(Definition taken from IS0 31/12.) gives a list of subscripts.

List of quantities (based on IS0 3111)

Table 1 -

Quantity Definition21 Symbol Dimensiod) Unit

in M

Mass

Length I L m

Time t S

Temperature 0 0 OC

Area A L2 m2

Volume V L3 m3

Angular velocity co T-1 rad/s

V LT-1

Velocity m/s

Acceleration due to gravity41 LT-2 m/s2

Number or rotations per unit time T-1

Speed of rotation n s-1

Density Mass per unit volume ML-3 kg/m3

Force per unit area. Unless otherwise specified all

Pressure ML-‘T-2 Pa

pressures are gauge pressures, i.e. measured with

respect to atmospheric pressure.

(1 bar = lo5 Pa)

Kinematic viscosity V L2T-1 m2/s

Specific energy Energy per unit mass E LZT-2 J/kg

Power (general term) P MLZT-3

Reynolds number Re dimensionless

Diameter L

Flow rates

Mass rate of flow The mass rate of flow designates the external MT-’

kg/s

4,(4)

mass rate of flow of the pump, i.e. the rate of flow

discharged into the pipe from the outlet branch of

the pump.

NOTE - Losses or abstractions inherent to the

pump, i.e. :

a) discharge necessary for hydraulic balancing

of axial thrust;

b) cooling of bearings of the pump itself;

c) water seal to the packing;

d) leakage from the fittings, internal leakage,

etc.,

are not to be reckoned in the quantity delivered. On

the contrary, if they are taken at a point before the

flow measuring section, all derived quantities used

for other purposes, such as :

e) cooling of the motor bearings;

f) cooling of a gear box (bearings, oil cooler),

etc.,

should be added to the measured rate of flow.

---------------------- Page: 13 ----------------------

SIST EN ISO 5198:2000

IS0 5198 : 1987 (E)

Table 1 - List of quantities (based on IS0 3111) (continued)

Quantity Definition*)

Symbol Dimensiod) Unit

Volume rate of flow The outlet volume rate of flow is given by the

L3T-’ m3/s

equation

For the purposes of this international Standard, this

symbol may also designate the volume rate of flow

in a given section 5) of the pump outlet; it is the

quotient of the mass rate of flow in this section by

the density. (The section may be designated by

subscripts. )

Mean veloc :ity

The mean velocity of flow equal to the volume rate U LT-1

m/s

of flow divided by the pipe cross-section5)

Local velocity Velocity of flow at any point

V LT-1 m/s

Gauge pressure Any pressure used in this International Standard

ML-’ T-2 Pa

except atmospheric and vapour pressure; the effec-

tive pressure, relative to the atmospheric pressure.

Its value is

- positive if this pressure is greater than the

atmospheric pressure;

negative if this pressure is less than the

atmospheric pressure.

Atmospheric pressure

ML-’ T-2 Pa

(absolute)

Vapour pressure (absolute)

ML-’ T-2 Pa

Head

The energy per unit mass of fluid divided by gravita-

L m

tional acceleration.

Height

Elevation of a point above a reference plane.

2 m

If the point is below the reference plane, z is

negative.

Reference plane Any horizontal plane to be used as a datum for - -

height measurement. A materialized reference plane

may be more practical than an imaginary one for

measurement purposes.

Inlet impeller height (or eye

The height of the centre of the circle described by

7 m

height) the external point of the entrance edges of the first

impeller blades. In case of double inlet pumps, z, is

the higher impeller height.

The manufacturer should indicate the position of

this point with respect to precise reference points on

the pump.

Velocity head Height of fluid corresponding to the kinetic energy

per unit mass of fluid divided by gravitational ac-

celeration. Its value is given by the formula

a u*/2 g

Velocity head coefficient

A coefficient relating velocity head in the section a dimensionless

with the mean velocity in that section. It is defined

by the equation

A v3dA

USA

If v is constant, a = 1

Available velocity head The part of the velocity head contributing to the

total head. Its value is given by the formula

a, c/*/2 g where I< a, < a

See 8.1.1.3

Available velocity head coeff i-

A coefficient relating available velocity head in a dimensionless

cient section to the mean velocity in that section.

See 8.1 .I .3

---------------------- Page: 14 ----------------------

SIST EN ISO 5198:2000

IS05198 :I987 (E)

Table 1 - List of quantities (based on IS0 3111) (continued)

Quantity Definition*)

Symbol Dimensiod) Unit

Total head (in section i) Total head in a given section, i, is usually calculated L

as:Pei

Hi=zi +-+a,i$

Qi g

This equation assumes that pressure varies hydro-

statically in the section and that compressibility of

the liquid pumped may be neglected.

See 8.1 .I .2 concerning the correctness of this last

assumption.

Inlet total head Total head at inlet section 1

Outlet total head Total head at outlet section 2

Pump total head Algebraic difference between outlet total head H2

and inlet total head H, :

H2 - HI

Separate evaluation of H, and H2 is not always

necessary. Other methods may even be recom-

mended if compressibility is to be accounted for.

See 8.1 J.2.

Loss of head at inlet The difference between the total head of the liquid L

HJ1

at the measuring point, or possibly of the liquid

without velocity in the suction chamber, and the

total head of the liquid in the inlet section of the

Pump.

Loss of head at outlet The difference between the total head of the liquid

HJ2

in the outlet section of the pump, and the total head

of the liquid at the measuring point.

Inlet total head increased by the head (in flowing

Net positive suction head; NPSH

(NPSH)

liquid) corresponding to the atmospheric pressure at

the test location and decreased by the sum of the

head corresponding to the vapour pressure of the

pump liquid at the inlet temperature and of the inlet

impeller height.

(NPSH) = H, + !k- - L - z,

elg e1g

NOTES

1 To maintain consistency between precision class

and engineering classes I and II, the arbitrary defini-

tion of (NPSH) is the same.

Therefore, in calculating (NPSH) values, the value

of aa is taken to be equal to unity (see velocity head

coefficient).

2 Local velocity distribution may influence (NPSH)

performance of the pump. Limitation of local veloc-

ity variation is given in clause 12.

3 It is necessary to make a distinction between

the (NPSH) required at given flow and speed

of rotation for a given pump - this is specified

by the manufacturer;

the (NPSH) available for the same flow,

which is inferred from the installation;

- the cavitation test (NPSH).

Subscripts may be used to differentiate these quan-

tities [for example (NPSH), when the value required

by the pump is concerned, (NPSH), when the

available value is concerned and (NPSH), when

cavitation test (NPSH) is concerned].

Critical net positive suction head Net positive suction head associated with

(NM-H, L

[2 + (K/2)1 % either of head drop in the first stage

or of the efficiency drop.

---------------------- Page: 15 ----------------------

SIST EN ISO 5198:2000

ISO5198:1987 (E)

Table 1 - List of quantities (based on IS0 3111) (concluded)

Quantity Def initiod Symbol Dimensiod Unit

Type number A number defined by the equation K dimensionless

2n n (q>)l/* cr) q;l/*

,I7314

(gH’)3’4

where q; is the volume rate of flow per eye and H'

is the head of the first stage. This quantity shall be

calculated at the best efficiency point.

Pump power input Mechanical power transmitted to the pump shaft. P ML*T-3 W

Driver power input Power input to driving unit. ML*T-3 W

Psr

Pump power output The power transferred to the liquid at its passage ML*T-3 W

through the pump

pu = eqvgff = Q4VE

Pump efficiency

?f=-

dimensionless

Overall efficiency

dimensionless

qgr = p

1) Further symbols used in the thermodynamic method are given in table 9.

2) In order to avoid any error of interpretation, it is deemed desirable to reproduce the definitions of quantities and units as given in

**...**

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