EN 16480:2021
(Main)Pumps - Rotodynamic pumps - Minimum required efficiency of water pumps and determination of Minimum Efficiency Index (MEI)
Pumps - Rotodynamic pumps - Minimum required efficiency of water pumps and determination of Minimum Efficiency Index (MEI)
This document specifies performance requirements (methods and procedures for testing and calculating) for determining the Minimum Efficiency Index (MEI) of rotodynamic glanded water pumps for pumping clean water, including where integrated in other products.
The pump types and sizes covered by this document are described in the Annex A. These pumps are designed and produced as duty pumps for pressures up to 16 bar for end suction pumps and up to 25 bar for multistage pumps, for all pumps designed for fluid temperatures between −10 °C and +120°C. Also covered are 4" (10,16 cm) and 6" (15,24 cm) submersible multistage pumps designed for fluid temperatures between 0 °C and 90 °C.
Pumpen - Kreiselpumpen - Geforderte Mindesteffizienz für Wasserpumpen sowie Bestimmung des Mindest-Effizienzindexes (MEI)
Dieses Dokument legt Leistungsanforderungen (Methoden und Verfahren zur Prüfung und Berechnung) zur Bestimmung des Mindest-Effizienzindex (MEI) von Wasserpumpen in Kreiselpumpenbauart mit Stopfbuchsen zum Pumpen von sauberem Wasser einschließlich von Produkten, in welche diese Pumpen integriert sind, fest.
Die Pumpentypen und Pumpengrößen, die von diesem Dokument abgedeckt sind, werden im Anhang A beschrieben. Diese Pumpen werden als Pumpen für Drücke bis 16 bar bei Pumpen mit axialem Eintritt und bis 25 bar bei mehrstufigen Pumpen und bei allen Pumpen für Mediumtemperaturen zwischen −10 °C und +120 °C ausgelegt und hergestellt. Ebenfalls abgedeckt sind mehrstufige Tauchpumpen der Größe 4″ (10,16 cm) oder 6″ (15,24 cm) für Mediumtemperaturen zwischen 0 °C und 90 °C.
Pompes - Pompes rotodynamiques - Rendement minimal requis des pompes à eau et détermination de l'Indice de rendement minimal (MEI)
Le présent document spécifie les exigences de performance (méthodes et modes opératoires d’essais et de calculs) pour la détermination de l’indice de rendement minimal (MEI) des pompes à eau rotodynamiques dotées d’un dispositif d’étanchéité employées pour pomper de l’eau propre, y compris les pompes intégrées dans d’autres produits.
Les types et les gammes de pompe visés par le présent document sont décrits dans l’Annexe A. Ces pompes sont conçues et fabriquées comme des pompes de service pour des pressions inférieures ou égales à 16 bar pour les pompes à aspiration en bout et inférieures ou égales à 25 bar pour les pompes multi-étagées, pour toutes les pompes conçues pour des températures de fluides comprises entre -10 °C et +120 °C. Sont également couvertes les pompes multi-étagées de 10,16 cm (4") et 15,24 cm (6") pour les pompes submersibles multi-étagées à des températures de fluides comprises entre 0 °C et 90 °C.
Črpalke - Centrifugalne črpalke - Minimalna zahtevana učinkovitost vodnih črpalk in določevanje minimalnega indeksa učinkovitostii (MEI)
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
01-december-2021
Nadomešča:
SIST EN 16480:2016
Črpalke - Centrifugalne črpalke - Minimalna zahtevana učinkovitost vodnih črpalk
in določevanje minimalnega indeksa učinkovitostii (MEI)
Pumps - Rotodynamic pumps - Minimum required efficiency of water pumps and
determination of Minimum Efficiency Index (MEI)
Pumpen - Kreiselpumpen - Geforderte Mindesteffizienz für Wasserpumpen sowie
Bestimmung des Minimum Effizienz Indexes (MEI)
Pompes - Pompes rotodynamiques - Rendement minimal requis des pompes à eau et
détermination de l'Indice de rendement minimal (MEI)
Ta slovenski standard je istoveten z: EN 16480:2021
ICS:
23.080 Črpalke Pumps
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EN 16480
EUROPEAN STANDARD
NORME EUROPÉENNE
October 2021
EUROPÄISCHE NORM
ICS 23.080 Supersedes EN 16480:2016
English Version
Pumps - Rotodynamic pumps - Minimum required
efficiency of water pumps and determination of Minimum
Efficiency Index (MEI)
Pompes - Pompes rotodynamiques - Rendement Pumpen - Kreiselpumpen - Geforderte Mindesteffizienz
minimal requis des pompes à eau et détermination de für Wasserpumpen sowie Bestimmung des Minimum
l'Indice de rendement minimal (MEI) Effizienz Indexes (MEI)
This European Standard was approved by CEN on 11 July 2021.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2021 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 16480:2021 E
worldwide for CEN national Members.
Contents Page
European foreword . 3
Introduction . 4
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
3.1 List of quantities with definitions . 5
3.2 General definitions . 7
4 Symbols and abbreviations . 8
5 Minimum Required Efficiencies and Minimum Efficiency Index . 10
5.1 The concept of “house of efficiency” . 10
5.2 Mathematical representation of minimum required efficiency . 12
5.3 Minimum efficiency at part load and overload . 13
5.4 Minimum Efficiency Index . 13
6 Determination of the Efficiency of a Test Pump . 16
6.1 General . 16
6.2 Test Procedures . 16
6.3 Test conditions . 17
6.4 Measurement uncertainties . 18
6.4.1 Relevance . 18
6.4.2 Fluctuations . 18
6.4.3 Statistical evaluation of overall measurement uncertainty . 18
6.5 Evaluation of test data . 20
6.5.1 Conversion of the test results to the nominal speed of rotation or to the nominal electric
frequency . 20
6.5.2 Performance curves . 21
6.5.3 Determination of the values relevant for the qualification of MEI . 22
6.5.4 Procedures for testing and/or evaluation of special pump types . 23
7 Proving the Minimum Efficiency Index of a pump size . 24
7.1 General remarks . 24
7.2 Determination of the Minimum Efficiency Index of a pump size . 24
Annex A (normative) Pump types in scope . 27
Annex B (informative) General remarks on the efficiency of rotodynamic pumps . 29
Annex C (informative) Mean Values of Minimum Efficiency Index for a Pump Size . 31
C.1 General . 31
C.2 Confidence interval on the mean value . 32
C.3 Outlier test . 34
C.4 Numerical example . 35
Annex ZA (informative) Relationship between this European Standard and the Ecodesign
requirements of Commission Regulation (EU) No 547/2012 [OJEU L 165/28 of
26 June 2012] aimed to be covered . 37
Bibliography . 38
European foreword
This document (EN 16480:2021) has been prepared by Technical Committee CEN/TC 197 “Pumps”, the
secretariat of which is held by AFNOR.
This European Standard shall be given the status of a national standard, either by publication of an identical
text or by endorsement, at the latest by April 2022, and conflicting national standards shall be withdrawn at
the latest by April 2022.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN 16480:2016.
The main changes compared to the previous edition are as follows:
— the title and scope have been modified by the removal of the verification aspect throughout this document;
— Clause 3 on Terms and Definitions has been modified;
— Clause 6 on the determination of the Efficiency of a Test Pump has been updated;
— informative Annex D dealing with methods recommended for manufacturers to determine the mean
values of hydraulic quantities of a size relevant for MEI has been deleted;
— informative Annex E giving a numerical example and informative Annex F describing the application of
mathematical statistics on tests have been deleted;
— informative Annexes G, H and I, dealing with measurement uncertainties, the methodology of the
verification procedure and the reporting of test results, respectively, have been deleted;
— the Annex ZA showing the relationship between this European Standard and the Ecodesign requirements
of Commission Regulation (EU) No 547/2012 has been updated.
This document has been prepared under a Standardization Request given to CEN by the European Commission
and the European Free Trade Association, and supports essential requirements of EU Directive(s) /
Regulation(s).
For relationship with EU Directive(s) / Regulation(s), see informative Annex ZA, which is an integral part of
this document.
Any feedback and questions on this document should be directed to the users’ national standards body. A
complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organisations of the following
countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of North Macedonia,
Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.
Introduction
Purpose and content of this document
The water pumps within the scope of this document are typically produced and sold by pump manufacturers
as series of large to very large numbers. The performance characteristics of pumps of one size produced by a
manufacturer show some scatter caused by manufacturing tolerances but are described by mean values and
curves which represent that size.
The total consumption of electric energy by water pumps installed in applications within the scope of this
document depends on the total number of installed pumps of each size and on its mean efficiency. The quality
of a size in respect to its mean efficiency is quantitatively described by the Minimum Efficiency Index (MEI)
which is defined and used in this document. To achieve a certain value of the Minimum Efficiency Index (MEI),
a corresponding minimum value of the mean efficiency of a size is required.
This document defines – for each pump type and size within the scope of this document - the minimum
required value of efficiency regarding a certain value of the Minimum Efficiency Index (MEI).
Normally, the qualification of a pump size for a certain MEI value done by the manufacturer will be based on
tests and evaluations made on a sample of pumps of this size. Tests and evaluations carried out for the purpose
of qualifying the corresponding size should fulfil certain requirements:
— From the tests on the sample pumps, it becomes possible to predict for the corresponding size the
confidence intervals within which the true mean values of efficiencies which are relevant for the
qualification are enclosed with a sufficiently high probability. Only in that way, the qualification of the size
in respect to a required and/or indicated value of Minimum Efficiency Index (MEI) will ensure that the
aspired effect of energy saving will be reached;
— This document provides manufacturers with a test procedure which confidently provides the MEI value
which is representative of the pump size.
Caused by technical alignment procedures of the single pump components e.g. bearings or shaft seals the
performance of the pump is gained after a certain running-in time.
Ways to prove the Minimum Efficiency Index (MEI) of a pump size
This document describes different ways how manufacturers can achieve the qualification of a pump size for a
certain value of the Minimum Efficiency Index (MEI)
The MEI value shall be based on the mean value of the type series. Annex C describes methods to determine
the mean value of MEIs and their confidence intervals.
A test to determine MEI-values on pumps of the size in question according to the requirements given in 6.2 to
6.4 of this document as well as evaluations as described in 6.5 of this document needs application of the
methodology and procedure described in Clause 5 of this document.
Relevance of clauses of this document for qualification
Clause 5 describes nominal values of minimum required efficiency for a certain value of the Minimum
Efficiency Index (MEI) and is generally relevant when applying this document.
Clause 6 specifies test procedures, test conditions and evaluations and has to be applied to determine mean
values of a size by tests on sample pumps of a certain size.
Clause 7 describes the procedure to be applied by a manufacturer in order to determine particular threshold
values of efficiency for a certain value of the Minimum Efficiency Index (MEI) of a size and to prove the
justification of this MEI value by the fulfilment of criteria for the mean efficiency values.
1 Scope
This document specifies performance requirements (methods and procedures for testing and calculating) for
determining the Minimum Efficiency Index (MEI) of rotodynamic glanded water pumps for pumping clean
water, including where integrated in other products.
The pump types and sizes covered by this document are described in the Annex A. These pumps are designed
and produced as duty pumps for pressures up to 16 bar for end suction pumps and up to 25 bar for multistage
pumps, for all pumps designed for fluid temperatures between −10 °C and +120 °C. Also covered are 4”
(10,16 cm) and 6” (15,24 cm) submersible multistage pumps designed for fluid temperatures between 0 °C
and 90 °C.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
EN ISO 9906:2012, Rotodynamic pumps — Hydraulic performance acceptance tests — Grades 1, 2 and 3 (ISO
9906:2012)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at https://www.electropedia.org/
— ISO Online browsing platform: available at https://www.iso.org/obp
1)
3.1 List of quantities with definitions
3.1.1
reynolds number
dimension less number that gives a measure of the ratio of inertial forces to viscous forces and consequently
quantifies the relative importance of these two types of forces for given flow conditions; in this document, it
is defined by the relation:
Du⋅
imp
Re =
ν
where u is the peripheral velocity at the outer impeller diameter D
imp
3.1.2
(volume) rate of flow
external rate of flow of the pump, i.e. the rate of flow discharged into the pipe from the outlet branch of the
pump
Note 1 to entry: Losses or abstractions inherent to the pump, i.e.:
— discharge necessary for hydraulic balancing of axial thrust;
1)
3.1 gives specific definitions of terms - in deviation of EN ISO 9906:2012 - used in this document, together with any
associated symbols which have been allocated and is based on ISO 80000.
— cooling of bearings of the pump itself;
— water seal to the packing;
Note 2 to entry: Leakage from the fittings, internal leakage, etc., is not to be reckoned in the rate of flow. On the
contrary, all derived flows for other purposes, such as cooling of the motor bearings; cooling of a gear box (bearings, oil
cooler), etc. are to be reckoned in the rate of flow.
Note 3 to entry: Whether and how these flows shall be taken into account depends on the location of their derivation
and of the section of flow-measurement respectively.
3.1.3
motor power input
power (P ) absorbed by the pump driver
3.1.4
pump efficiency
P Pump power output
hyd
η
P Pump power input
3.1.5
motor efficiency
P
Pump power input
η
mot
P Motor power input
3.1.6
overall efficiency
P
Pump power output
hyd
η
tot
Motor power input
P
3.1.7
specific speed
dimensional number characterising the impeller type (radial, semi-axial, axial) of rotodynamic pumps
Q
BEP
nn⋅
sN
0,75
H
BEP
Note 1 to entry: For multistage pumps, H is the head per stage which results from dividing the total pump head at
BEP
the point of best efficiency by the number of stages i.
Note 2 to entry: The specific speed of an individual pump or the mean specific speed of a pump size is a (dimensional)
value which characterizes the impeller shape (radial, semi-axial, axial) of the pump or the size. The numerical value of
the specific speed is defined by a formula given in this Clause by using special units for the quantities contained in this
formula. As described in Clause 5, the specific speed is one of the parameters, which the nominal values of minimum
required efficiency depend on.
Note 3 to entry: Specific speed can be interpreted as the rotational speed of the pump with a flow of 1 m /s and the
head of 1m and is described in [1/min], although this is not due to the balance of units.
=
==
==
==
3.1.8
minimum efficiency index (MEI)
value which determines the minimum required efficiency for the qualification criteria and, thereby, is a
measure of the quality of a pump size in respect to efficiency
Note 1 to entry: Dimensionless scale unit for hydraulic pump efficiency at BEP, PL and OL.
Note 2 to entry: The MEI is the result of a statistical analysis of the performances of a large number of commercial
pump sizes, and corresponds to the various “quartiles” of the statistical distribution.
EXAMPLE MEI = 0,40 corresponds to the efficiency performance level that 40 % of the pumps on the market do not
[ ]
meet 7 .
3.2 General definitions
3.2.1
qualification
procedure where the manufacturer of the pump size proves, by appropriate methods, a given value of the MEI
(e.g. the value on the nameplate)
Note 1 to entry: Generally, the qualification criteria refer to the mean values of the size which are valid for the full
impeller diameter and which will be determined by tests and evaluations on pumps of the respective size. These mean
efficiency values and their confidence intervals are compared to nominal values of minimum required efficiency. Also,
these values depend on parameters (see Clause 5) the values of which partly result from the tests and are determined
with some uncertainty or tolerance.
3.2.2
minimum required efficiency η
min,requ
value of efficiency that shall be reached in order to fulfil a particular MEI value
Note to entry: The value of minimum required efficiency depends on certain properties of the pump size (pump type,
nominal speed of rotation, flow rate at best efficiency point and specific speed) and on the Minimum Efficiency Index
(MEI). For one size, different minimum required efficiencies are relevant at best efficiency point, at specified part load
and overload operating points, respectively.
3.2.3
particular threshold values of efficiency (η )
threshold
nominal values calculated from the minimum required efficiency respecting random sample scatter and
measurement uncertainty
3.2.4
pump size
range of pumps characterized by certain dimensions and performance (e.g. nominal diameter of discharge
flange and nominal impeller diameter for end-suction and multistage pumps, number of stages for multistage
pumps, nominal outer casing diameter in the case of submersible multistage pumps) and given in catalogues
by a manufacturer
Note to entry: In a Q-H-chart each pump size covers a certain range of Q- and H-values. Within this range each duty point
can be served by a pump of the corresponding pump size through adapting its Q-H-curve by impeller trimming, i.e. by
cutting down the outer impeller diameter to an appropriate value. The upper limit of the Q-H-range covered by one pump
size is determined by the full diameter of the impeller corresponding to this size.
3.2.5
full impeller diameter of a pump size
impeller with the maximum diameter for which performance characteristics are given for a pump size in the
catalogues of a water pump manufacturer
3.2.6
best efficiency point, BEP
operating point where the greatest value of pumps efficiency is obtained, at nominal speed of rotation
3.2.7
part load PL
particular operating point in the range of operating points with lower flow than best efficiency point, at
nominal speed of rotation
3.2.8
overload OL
particular operating point in the range of operating points with higher flow than best efficiency point, at
nominal speed of rotation
4 Symbols and abbreviations
Table 1 gives an alphabetical list of symbols used and Table 2 gives a list of subscripts. As far as possible, the
quantities, definitions and symbols used in this document comply with those used in EN ISO 9906:2012.
Quantities, definitions and symbols used in EN ISO 9906:2012, but not needed in this document are not
contained in Clause 5 and Tables 1 and 2 while these tables contain some quantities, definitions and symbols
which are not used in EN ISO 9906:2012.
In this document all formulae are given in coherent SI-units.
Table 1 — Alphabetical list of basic letters used as symbols
Symbol Quantity Unit
A Area 2
m
C Constant pure number
D Diameter m
e Measurement uncertainty, relative value pure number
f Frequency −1
s , Hz
g Acceleration due to gravity 2
m/s
H Pump total head m
k Number of instrument readings or sample pure number
pumps
m Mass kg
M Number of pumps of a sample pure number
n Speed of rotation −1 −1
s , min
N Number of instrument readings pure number
n Specific speed −1
s min
p Pressure Pa
p Probability pure number
P Power W
Symbol Quantity Unit
Q (Volume) rate of flow 3
m /s
s Standard deviation of a sample according to special quantity
t Tolerance factor, relative value pure number
t Time s
t Student’s factor pure number
T Torque Nm
u Peripheral velocity m/s
U Mean velocity m/s
U Voltage V
v Local velocity m/s
V Volume 3
m
x General quantity according to special quantity
y General quantity according to special quantity
z Height above reference plane m
z Number of produced pumps pure number
η Efficiency pure number
θ Temperature °C
ν Kinematic viscosity 2
m /s
ρ Density 3
kg/m
ω Angular velocity rad/s
σ Standard deviation of normal distribution according to special quantity
NOTE For a list of concise designations (short-term description) of pump types in scope, see Annex B.
Table 2 — List of letters and figures used as subscripts
Subscript Meaning
1 electrical
2 mechanical
abs absolute
amb ambient
annual per year
curve on fitting curve
BEP at best efficiency point
mot motor
D datum
exp experimentally determined
Subscript Meaning
G guaranteed
H pump total head
I numbering index
J numbering index
imp impeller
man manufacturing
max maximum permissible
mean mean value of pump series
min,requ minimum required
N nominal
OL overload
Pd pre-defined
P power
PL part load
Q (volume) flow rate
R random
S specific, systematic
sync synchronous
tot total, overall
true true value
T torque
T translated
v vapour
x of quantity x
y % for probability of y %
η Efficiency
hyd hydraulic
5 Minimum Required Efficiencies and Minimum Efficiency Index
5.1 The concept of “house of efficiency”
To achieve the goal of energy saving by replacing less energy efficient pumps with pumps which are qualified
in respect to fulfilling criteria of minimum required efficiency, two important aspects shall be taken into
account:
1) The required minimum values of η shall be fulfilled by the mean values of the qualified pump sizes
min,req
which are produced and sold in large numbers. Therefore, these mean values and their confidence
intervals shall be determined by appropriate methods and then be compared to minimum required values
(Formula 4) which are based on general physical interrelations (see Annex B) as well as on a statistical
evaluation of existing pumps of ”state of the art” design and manufacturing quality.
2) Not only the value of η is relevant for energy consumption and saving by pumps, but also the efficiency
BEP
in the part load and overload ranges of operation. This is caused by two reasons:
The product program of pump manufacturers for a certain pump type is – from economic reasons –
subdivided into a limited number of different pump sizes which each cover a certain range of flow rate Q
and pump head H. This leads to the effect that most unlikely for any Q-H duty point (i.e. the operating point
specified by the pump user which normally is the most probable point of operation) for a pump
application, a pump size will exist for which its best efficiency point is identical to the required duty point.
The selection of the “best choice” size for a given application will most often cause the duty point to be a
slight “off-design”, i.e. part load or overload, point of the selected size. (For more information to aspects
of pump selection, see Annex B)
Even if the best efficiency point of a pump size fits exactly to a required duty point, the pump will normally
be operated in a range of operation and not only at its duty point. This can result from changes or
variations of the hydraulic resistance of the circuit (caused either by varying demand of system flow rate
or by long time effects as, e.g. internal incrustation of pipes) or, in the case of parallel operation of pumps,
from variable operation conditions when different numbers of pumps are running.
Therefore, the qualification of a pump size in respect to minimum required efficiency is based on the so-called
concept “house of efficiency” which includes two criteria A and B.
Criterion A is the minimum efficiency requirement at the best efficiency point (BEP) of the pump size:
A. (1)
ηη≥
( ) ( )
BEP BEP
mean min, requ
Criterion B is the minimum efficiency requirement at specified part load (PL) and overload (OL) operating
points of the pump size:
ηη≥
B. (2)
( ) ( )
PL PL
mean min,requ
ηη≥ (3)
( ) ( )
OL OL
mean min,requ
In this document, the operating points which shall be representative for the efficiency in the part load and
overload range are fixed at Q = 0,75 Q and Q = 1,1 Q .
PL BEP OL BEP
All efficiency values in the criteria given above are mean values of the pump size and are to be taken for pumps
of this size with full impeller diameter.
As a result, the mean efficiency curve of the size has to show a high maximum and a broad width at high level
to fulfil the criteria for qualification.
In Figure 1, the representation of the two criteria is shown in a Q-η diagram. To be qualified, the mean
efficiency curve of the size with its maximum at the best efficiency point shall not penetrate into the “roof” of
the “house of efficiency”.
Key
η pump efficiency
Figure 1 — “House of Efficiency” — explanatory representation
5.2 Mathematical representation of minimum required efficiency
The minimum required efficiency values for pump sizes fulfilling the qualification criteria A and B are based
on scientific analyses of the attainable efficiency of rotodynamic pumps as well on a statistical evaluation of
data collected from several questionnaires sent to European pump manufacturers in 2007.
The collected data comprises all pump types within the scope of this document. The specific speed n of the
s
−1 −1
pumps forming the database ranges from 6 min to 110,5 min and the range of flow rate at best efficiency
3 3
Q is from 1,82 m /h to 1 200 m /h. The performance data supplied by the European manufacturers were
BEP
assumed to be valid for the full diameter of the respective pump sizes.
In respect of the general physical dependency of attainable mean values of efficiency on main parameters (see
Annex B), the collected data have been ordered according to a representation in the form η = f (n , Q )
BEP s BEP
for each pump type and nominal speed within the scope. This correlation is described by mathematical
Formula (4). The form of the formula is based on previous investigations. The various steps to come from the
collected data to the quantitative description of the relation η = f (n , Q ) in the form of a 3-dimensional
BEP s BEP
quadratic polynomial approximation are presented in more detail in the final report of the evaluation study.
The mathematical formula describing the relation η = f (n , Q ) is the following:
BEP s BEP
2 2
η =−11, 48 ln n −⋅0, 85 ln Q −⋅0,38 ln nQ⋅ ln + 88,59ln n + 13, 46⋅ ln Q − C (4)
( ) ( ) ( ) ( ) ( ) ( )
( ) ( )
BEP s BEP s BEP s BEP
where
η is expressed in [%];
BEP
−1
n is expressed in [min ];
s
Q is expressed in [m /h];
BEP
C: constant is expressed in [%], depending on Minimum Efficiency Index (MEI), see 5.4.
The result calculated from Formula (4) has to be rounded to the 1st digit after the decimal point.
−1 −1
NOTE 1 The mathematical range of validity of the formula is6 min ≤ n ≤ 120 min
s
3 3
2 m /h ≤ Q ≤ 1 000 m /h.
BEP
The physical range of validity of the formula is η ≤ 88 %
BEP
NOTE 2 The limitation of the physical range of validity to a maximum value of η results from the fact that the
BEP
hydraulic and mechanical losses in commercially designed and manufactured rotodynamic pumps cannot fall below a
lowest limit.
NOTE 3 Further reduction of losses would need special measures in design and manufacturing which would lead to
unacceptable efforts and costs and/or would be incompatible with other pump operating requirements as, for example,
reliability, good cavitation performance, low noise and vibration levels.
Formula (4) is valid for all pump types within the scope of this document pumping clean cold water. In the
case of vertical multistage pumps (MS-V), it is valid for a minimum stage number of 3, in the case of
submersible multistage pumps (MSS) for a minimum stage number of 9. Generally, the formula is valid for the
full impeller diameter of a pump size.
The efficiency values concern pump efficiency only, not the overall efficiency (wire-to-water) even in the case
of close coupled pump-motor units.
5.3 Minimum efficiency at part load and overload
In [7], the pump data given by the manufacturers was also evaluated at selected part load (0,75 Q ) and
BEP
overload (1,10 Q ) operating points.
BEP
Part load and overload coefficients are defined by Formula (5):
η η
PL OL
xx; (5)
PL OL
η η
BEP BEP
were calculated for each pump type. The mean value of these coefficients was found to be x = 0,947 and
PL
x = 0,985 for all pump types in good approximation.
OL
Using the relation described in 5.2 for η , the minimum efficiency requirements for the selected operating
BEP
points at part load and overload are calculated by Formulae (6) and (7):
(6)
ηη0, 947⋅
( ) ( )
PL BEP
min, requ min, requ
(7)
ηη0, 985⋅
( ) ( )
OL BEP
min, requ min,requ
5.4 Minimum Efficiency Index
By varying the constant C in the formula for η , the curves resulting from Formula (4) and plotted in a n -
BEP s
η - diagram for constant values of Q are shifted in the vertical η-direction (see Figure 3 as an
min,requ BEP
example). With a chosen value of C for a pump type and rotational speed within the scope, the existing pumps
of this type produced by the European manufacturers are split into a percentage of the total number of pump
sizes which already fulfil the corresponding minimum efficiency requirement (in respect to criteria A and B)
and the (complementary) percentage of those which do not fulfil this requirement., Consequently, pumps not
fulfilling the requirement will be replaced on the market by pumps which are qualified in respect to the criteria
A and B. The quantitative effect of the qualification criteria (finally determined by the value C) on the market
and energy saving effect is characterized by the Minimum Efficiency Index (MEI). In the statistical evaluation
=
=
==
[7], the Minimum Efficiency Index (MEI) was determined such that its value, multiplied by 100, indicates the
percentage of existing pump sizes which do not fulfil the qualification criteria A and B for the corresponding
value of C. To come to these results, the data for each pump given by the pump manufacturer were taken as
being representative for the total number of pumps of the corresponding size with full impeller diameter.
NOTE 1 The Minimum Efficiency Index (defined as described above) is a measure for the quality of a pump size in
respect to efficiency. At the lower limit MEI = 0, the corresponding efficiencies of pump sizes can be achieved on a low
level of design and manufacturing. For values of MEI > 0,7 the corresponding efficiencies of pump sizes can only be
achieved by a very special hydraulic design which only aims at high efficiency and does not respect other hydraulic
aspects as, e.g. good cavitation performance, and additionally by exceptional measures in mechanical design and
manufacturing.
NOTE 2 The maximum effect of reducing energy consumption by using pumps with high MEI will only be achieved if
the pumps are carefully selected for required duties (see Annex B).
Table 3 shows the values of C for the pump types within the scope and for different values of the Minimum
Efficiency Index (MEI).
Table 3 — Values of the constant C for different values of the Minimum Efficiency Index (MEI)
Minimum Efficiency Index
0,10 0,20 0,30 0,40 0,50 0,60 0,70
C (ESOB 1450) 132,58 130,68 129,35 128,07 126,97 126,10 124,85
C (ESOB 2900) 135,60 133,43 131,61 130,27 129,18 128,12 127,06
C (ESCC 1450) 132,74 131,20 129,77 128,46 127,38 126,57 125,46
C (ESCC 2900) 135,93 133,82 132,23 130,77 129,86 128,80 127,75
C (ESCCi 1450) 136,67 134,60 133,44 132,30 131,00 130,32 128,98
C (ESCCi 2900) 139,45 136,53 134,91 133,69 132,65 131,34 129,83
C (MS-V 2900) 138,19 135,41 134,89 133,95 133,43 131,87 130,37
C (MSS 2900) 134,31 132,43 130,94 128,79 127,27 125,22 123,84
Examples of efficiency values resulting from Formula (4) for certain values of MEI are shown in Figures 2
and 3.
-1
Figure 2 — Two-dimensional representation of η = f (n ,Q ) for ESOB, n = 2 900 min and
BEP s BEP
MEI = 0,70 (see Table 3)
3 −1
Figure 3 — η = f (n ) for ESOB with Q = 32 m /h, 2 900 min and for different values of MEI
BEP s BEP
(see Table 3)
For the choice of the value of MEI within the qualification procedure, the following applies:
1) the value of the Minimum Efficiency Index (MEI) can be chosen (and proven by a qualification procedure)
by the pump manufacturer to indicate the quality of a pump size in respect to efficiency;
2) minimum values of MEI can be fixed by law, or EU regulations for market acceptance in order to reduce
overall energy consumption.
Examples of graphical representations for one pump type and rotational speed are given in Figures 2 and 3.
Figure 2 shows the principal dependence of η on the specific speed n and on the flow rate at best
min,requ s
efficiency Q . In Figure 3, the effect of varying the value of MEI on η is demonstrated.
BEP min,requ
In the frame of qualification of a pump size, the values of Q and n — which η depends on — shall
BEP s min,requ
themselves be determined by tests on sample pumps and are not known a priori nor do they result from the
tests as exact or true values. The determination of Q and n from tests on sample pumps is subjected to
BEP s
effects of manufacturing tolerances within the size (see Annex C) and of measurement uncertainties (see
Clause 6). Therefore, the values of Q and n can only be determined to be confined to corresponding
BEP s
confidence intervals. When calculating η by the means of Formula (4) the uncertainties of Q and
min,requ BEP
n propagate into the result. In this document, the value of η which is calculated by the means of
s min,requ
Formula (4) using as input the measured (and – in the case of a sample of M > 1 pumps – arithmetically
averaged) values of Q and n is called nominal value of minimum required efficiency.
BEP s
6 Determination of the efficiency of a test pump
6.1 General
This clause specifies performance tests and evaluations on test pumps drawn at random out of a size which
are carried out by a manufacturer in the case he has decided to qualify this size in respect to a certain value of
Minimum Efficiency Index (MEI) by applying these tests and evaluations.
Such tests and evaluations shall provide the necessary information on the actual performance values of test
pumps needed for the qualification procedure described in Clause 7. These values comprise:
1) the flow rate at best efficiency point Q from which also the values of flow rate Q and Q at specified
BEP PL OL
part load and overload operating points (defined in 5.1), respectively, can be derived,
2) the maximum efficiency η at Q and the values of efficiency η and η at the corresponding
BEP BEP PL OL
values of flow rate Q and Q ,
PL OL
3) the specific speed n which is needed to determine the minimum required efficiencies (see 5.2 to 5.4).
s
Regarding the requirements on test installations and measuring equipment, EN ISO 9906:2012 is to be
applied.
6.2 Test procedures
Test procedure and measurement instrumentation shall be in accordance with EN ISO 9906:2012 grade 2. The
acceptance grade should not be used. The exception for input power of 10 kW and below (see
EN ISO 9906:2012, 4.4.2) shall not be considered.
For pumps (P ) < 1 kW it is strongly recommended to test a sample number higher than 3 in order to ensure
a higher reliability to determine mean values and keep confidence intervals small.
1) Tests shall be carried out on test stands of the manufacturer or of laboratories in accordance to the
methods and in the test arrangements, specified in EN ISO 9906:2012;
2) the pump performance shall be determined between the pump’s inlet flange and discharge flange.
The conditions necessary to ensure satisfactory measurement of the performance characteristics are defined
in 6.3.
Recommendations and general guidance about suitable pipe arrangements to ensure satisfactory
measurements for flow and head are given in EN ISO 9906:2012, A.3 and, if necessary, they can be used in
conjunction with the ISO Standards on measurement of flow rates in closed conduits concerning the different
methods (see EN ISO 9906:2012, A.1).
As explained in EN ISO 9906:2012, A.1.4, the pump power input which is needed to determine the pump
efficiency can be experimentally determined either:
— by measurements of rotational speed and torque, or
— by electric power measurements.
Where the electrical power input to an electric motor coupled directly to the pump is used as a means of
determining the pump power input, the motor should be operated only under conditions where the efficiency
is known with sufficient accuracy. Motor efficiency should be determined in accordance with the
recommendations of IEC 60034-2-1:2014, IEC 60034-2-2:2010, or IEEE 112:2017 method B and should be
stated by the motor manufacturer or derived through a unit specific motor test.
In the case of testing a pump with an integrated electric motor in the frame of the MEI Determination, the
motor efficiency dependent on the motor load shall be found out in a suitable way, e.g. by information given
by the motor manufacturer or by disassembling the test pump and calibrating the motor as described in the
previous paragraph.
For sizes of multistage pumps which are offered and sold by the manufacturer with different numbers of
stages, the tests on test pumps which should be representative (in respect to the efficiency) for the size shall
be carried out on pump versions with at least 3 stages for multistage pumps (MS-V) and with at least 9 stages
for submersible multistage pumps (MSS).
The test pumps taken out of a pump size shall have an impeller with the full diameter of the corresponding
pump size.
NOTE Trimming a pump of a given size by cutting down the impeller diameter will reduce the pump efficiency
compared to the efficiency of the same pump size with full diameter but overall saves energy as the trimmed impeller
suits the required duty point in the pumping system.
The test results shall be summarized in a report. Further guidance regarding the contents of a test report and
a suitable pump test sheet is given in EN ISO 9906:2012.
6.3 Test conditions
Tests shall be carried out with clean cold water. The duration of the test shall be sufficient to obtain repeatable
results; especially run-in effects shall be considered.
Run-in effects may take up to one day operating time.
All measurements shall be made under steady-state conditions (see 6.4).
The tests should be conducted under conditions where cavitation does not affect the performance of the pump.
NOTE If cavitation exists to a remarkable extent in the test pump during the tes
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