EN 16480:2016

SLOVENSKI STANDARD
01-julij-2016
ýUSDONH0LQLPDOQD]DKWHYDQDXþLQNRYLWRVWFHQWULIXJDOQLKYRGQLKþUSDON
Pumps - Minimum required efficiency of rotodynamic water pumps
Pumpen - Geforderte Mindesteffizienz bei Kreiselpumpen für Wasser
Pompes - Rendement minimum requis des pompes à eau rotodynamiques
Ta slovenski standard je istoveten z: EN 16480:2016
ICS:
23.080 ýUSDONH Pumps
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN 16480
EUROPEAN STANDARD
NORME EUROPÉENNE
May 2016
EUROPÄISCHE NORM
ICS 23.080
English Version
Pumps - Minimum required efficiency of rotodynamic
water pumps
Pompes - Rendement minimum requis des pompes à Pumpen - Geforderte Mindesteffizienz bei
eau rotodynamiques Kreiselpumpen für Wasser
This European Standard was approved by CEN on 4 March 2016.

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, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, 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: Avenue Marnix 17, B-1000 Brussels
© 2016 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 16480:2016 E
worldwide for CEN national Members.

Contents Page
European foreword . 4
Introduction . 5
1 Scope . 7
2 Normative references . 8
3 Terms and definitions . 8
3.1 General . 8
3.2 List of quantities with definitions . 8
3.3 Lists of basic letters and subscripts . 10
3.4 General definitions . 12
4 Minimum Required Efficiencies and Minimum Efficiency Index . 14
4.1 The concept of “house of efficiency” . 14
4.2 Mathematical representation of minimum required efficiency . 15
4.3 Minimum efficiency at part load and overload . 16
4.4 Minimum Efficiency Index . 17
5 Determination of the Efficiency of a Test Pump . 20
5.1 General . 20
5.2 Test Procedures . 20
5.3 Test conditions . 21
5.4 Measuring uncertainties . 22
5.5 Evaluation of test data . 24
6 Proving the Minimum Efficiency Index of a pump size . 29
6.1 General remarks . 29
6.2 Determination of the Minimum Efficiency Index of a pump size . 30
7 Verification of the Minimum Efficiency Index for a pump size . 31
7.1 General remarks . 31
7.2 Procedure and decision . 31
Annex A (normative) Pump types in scope . 35
Annex B (informative) General remarks on the efficiency of rotodynamic pumps . 37
Annex C (informative) Mean Values of a Size Relevant for its Minimum Efficiency Index . 39
Annex D (informative) Methods recommended for manufacturers to determine the mean
values of hydraulic quantities of a size relevant for MEI . 44
D.1 General remarks . 44
D.2 Determination of the mean efficiency of a pump size from a test on one single test
pump . 44
D.3 Determination of the mean efficiency of a pump size from a sample of M test pumps. 46
Annex E (informative) Numerical example. 49
Annex F (informative) Application of mathematical statistics on tests . 54
F.1 Purposes of applying statistics in the frame of qualification and verification . 54
F.2 Confidence interval . 55
F.3 Law of error propagation . 57
F.4 Numerical example . 57
Annex G (informative) Measurement uncertainties . 64
G.1 General remarks . 64
G.2 Determination of the overall measurement uncertainty of efficiency . 66
Annex H (informative) Explanations concerning the methodology of the verification
procedure and the probability of the results . 68
Annex I (informative) Reporting of Test Results . 71
I.1 Test Report Requirements . 71
I.2 Pump test sheet . 71
Annex ZA (informative) Relationship between this European Standard and the Essential
Requirements of EU Directive 2009/125/EC, establishing a framework for the
setting of ecodesign requirements of energy related products and implemented by
the European Commission Regulation (EU) No. 547/2012 . 73
Bibliography . 74

European foreword
This document (EN 16480:2016) has been prepared by Technical Committee CEN/TC 197 “Pumps -
Minimum required efficiency of rotodynamic water 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 November 2016, and conflicting national standards
shall be withdrawn at the latest by November 2016.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent
rights.
This document has been prepared under a mandate given to CEN by the European Commission and the
European Free Trade Association, and supports essential requirements of EU Directive 2009/125/EC.
For relationship with EU Directive 2009/125/EC, see informative Annex ZA, which is an integral part of
this document.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Introduction
Purpose and content of the standard
The water pumps within the scope of this European Standard 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 European Standard 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 standard. 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 European Standard defines – for each pump type and size within the scope of the standard - the
minimum required value of efficiency depending on the value of the Minimum Efficiency Index (MEI).
Also, this standard prescribes how the value of the Minimum Efficiency Index (MEI) of a pump size
indicated by the manufacturer can be verified by an independent institution (e.g. in the frame of market
surveillance). For the manufacturer of the pump size it is generally left free how to prove the indicated
value of the Minimum Efficiency Index (MEI) of a size. Nevertheless, this standard describes also a
method to prove by the manufacturer that the mean values of efficiency meet the requirements for
indicating 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. It is essential that tests and
evaluations carried out for the purpose of qualifying the corresponding size 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
make sure that the aspired effect of energy saving will be reached.
— If a pump size has been qualified according to the criteria described in this European Standard,
every test on one or more test pump(s) of the same size (with a full impeller diameter) which is
carried out in the frame of a verification procedure shall result with a very high probability in a
confirmation of the qualification.
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 and to verify the Minimum Efficiency Index (MEI) of a pump size
This European Standard describes different ways how manufacturers can achieve the qualification of a
pump size for a certain value of the Minimum Efficiency Index (MEI) and how this qualification can be
verified by an independent institution.
For the manufacturer, it is generally left free to choose and apply appropriate methods to prove that the
mean efficiency values of a size are at least equal to or higher than particular threshold values of
efficiency. These particular threshold values of efficiency are related to the value of the Minimum
Efficiency Index (MEI) to be indicated for the size. The way to determine these values of efficiency is
described in this standard. If the way chosen by the manufacturer to prove the MEI value of a size
deviates from the way mentioned in the next paragraph, the manufacturer has to document all tests,
evaluations and/or calculations which are carried out and the methods which are applied to prove the
justification of the indicated MEI value.
If the manufacturer decides to determine the mean performance values of the size by one of the
methods described in Annex D of this standard, he has to carry out tests according to the requirements
given in Annex C of this standard and evaluations as described in Annex C of this standard and to prove
– as described in Clause 7 of this standard – that the criteria for the achievement of a certain value of
the Minimum Efficiency Index (MEI) of the size are fulfilled. The test conditions, the results of test
evaluation and the fulfilment of the criteria are documented and stored. The time period to keep
documentation available for the authorities to prove conformity is fixed by the legal text.
The independent institution carries out tests on pumps of the size in question according to the
requirements given in 5.2 to 5.4 of this standard as well as evaluations as described in 5.5 of this
standard and applies the methodology and procedure described in Clause 4 of this standard.
For an independent institution, two ways are possible and specified by this standard to verify the value
of Minimum Efficiency Index (MEI) indicated by the manufacturer:
a) If the documentation of the qualification is presented by the manufacturer to the independent
institution on request, the procedure of verification executed by the independent institution is
based on the documentation of tests and evaluations done and documented by the manufacturer. In
this case, the documentation will be checked by the independent institution in respect to being in
accordance with requirements and criteria given in this standard.
b) If no documentation is presented by the manufacturer on request or if the documentation
presented by the manufacturer on request is not accepted as proof of the indicated value of MEI,
the independent institution carries out tests on pumps of the size in question according to the
requirements given in Annex C of this standard as well as evaluations as described in 5.5 of this
standard and applies the methodology and procedure described in Clause 4 of this standard.
Relevance of Sections of this standard for manufacturers or independent institutions
Clause 4 describes nominal values of minimum required efficiency for a certain value of the Minimum
Efficiency Index (MEI) and is generally relevant when applying this standard.
Clause 5 specifies test procedures, test conditions and evaluations and has to be applied
— by a manufacturer in the case that he decides to determine mean values of a size by tests on sample
pumps of this size (e.g. by methods described in Annex D),
— by an independent institution in the case that the Minimum Efficiency Index (MEI) of a pump size
shall be verified by the procedure described in Clause 7.
Clause 6 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.
Clause 7 describes the methodology and procedure to be applied by an independent institution in the
case that the Minimum Efficiency Index (MEI) of a size indicated by the manufacturer shall be verified
by third party tests on pumps of this size.
Annex C is concerned with mean values of a pump size which are relevant for manufacturers to prove
that a pump size achieves a certain value of the Minimum Efficiency Index (MEI).
1 Scope
This European Standard 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 standard 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, temperatures between -10 °C and +120 °C and 4” or 6” size for
submersible multistage pumps at operating temperatures within a range of 0 °C and 90 °C.
In addition, this standard specifies how the value of the Minimum Efficiency Index (MEI) of a pump size
indicated by the manufacturer can be checked by market surveillance.
Even if it is left free to the manufacturer of a pump size how to prove the rated value of the Minimum
Efficiency Index (MEI), nevertheless this standard specifies a method to prove that this rated value
meets the requirements within the confidence intervals with a sufficiently high probability.

Figure 1 — Scheme of application of this standard
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. 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
3.1 General
For the purposes of this European Standard, the quantities, definitions, symbols and units given in
EN ISO 9906 and in 3.2 apply. 3.2 gives specific definitions of terms - in deviation of EN ISO 9906 - used
in this European Standard, together with any associated symbols which have been allocated and is
based on ISO 80000.
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 standard comply with those used in
EN ISO 9906. Quantities, definitions and symbols used in EN ISO 9906, but not needed in this standard
are not contained in 3.2 and Tables 1 and 2, while these tables contain some quantities, definitions and
symbols which are not used in EN ISO 9906.
In this European Standard, all formulae are given in coherent SI-units.
3.2 List of quantities with definitions
For the purposes of this document, the following terms and definitions apply. Most of the terms and
definitions come from EN ISO 9906, except for the definition of MEI.
3.2.1
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 standard, it is defined by the relation:
Du⋅
imp
Re=
ν
where u is the peripheral velocity at the outer impeller diameter D
imp
3.2.2
(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;
— 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.
3.2.3
driver power input
power absorbed by the pump driver
3.2.4
pump efficiency
P
Hydraulic output
hyd
η
Pumppower input
P
3.2.5
driver efficiency
P
Pumppower input
η
dr
Driver power input
P
3.2.6
overall efficiency
P
hyd Pumppower output
η
tot
Driver power input
P
3.2.7
specific speed
dimensional number characterizing 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
BEP
head at the point of best efficiency by the number of stages.
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 an equation given in 3.2.7 by using special units for the
quantities contained in this equation. As described in Clause 4, the specific speed is one of the parameters which
the nominal values of minimum required efficiency depend on.
3.2.8
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.
For example, MEI = 0,40 corresponds to the efficiency performance level that 40 % of the pumps on the market do
not meet.
3.3 Lists of basic letters and subscripts
Table 1 — Alphabetical list of basic letters used as symbols
Symbol Quantity Unit
A Area m
C Constant pure number
D Diameter m
e Measurement uncertainty, relative value pure number
-1
f Frequency s , Hz
g Acceleration due to gravity m/s
H Pump total head m
k Number of instrument readings or sample pumps pure number
m Mass kg
M Number of pumps of a sample pure number
-1 -1
n Speed of rotation s , min
N Number of instrument readings pure number
-1
n Specific speed min
s
p Pressure Pa
p Probability pure number
P Power W
Q (Volume) rate of flow 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 m
x General quantity according to special quantity
Symbol Quantity Unit
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 m /s
ρ Density kg/m
ω Angular velocity rad/s
σ Standard deviation of normal distribution according to special quantity
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
dr driver
D datum
exp experimentally determined
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
Subscript Meaning
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
3.4 General definitions
3.4.1
qualification
procedure where the manufacturer of the pump size proves, by appropriate methods, the fulfilment of
the efficiency criteria defined in this standard
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 4) the values of which partly result from the tests
and are determined with some uncertainty or tolerance. Therefore, so-called particular threshold values of
efficiency are determined and used in the frame of the qualification procedure for comparison with the mean
values.
3.4.2
verification
procedure where an independent institution checks the result of the qualification procedure, in the
frame of market surveillance
Note 1 to entry: In this case, the tests and the evaluation of the test data are carried out according to Clause 5 of
this European Standard. The approval decision is taken according to the procedure described in Clause 7 of this
European Standard.
3.4.3
independent institution/market surveillance
organization mandated by the market surveillance for verification of MEI values indicated by
manufacturers
Note 1 to entry: These organizations are generally called independent institutions whatever the special type of
the institution (non-governmental organization (NGO), neutral institute, market surveillance authorities or
similar) may be.
Note 2 to entry: Neutral institutions or similar organizations can also be mandated by a manufacturer for the
qualification procedure, in this case they are not considered as independent institution when applying this
standard.
3.4.4
minimum required efficiency
η
min,requ
value of efficiency that have to be reached in order to fulfil a particular MEI value
Note 1 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.
3.4.5
particular threshold values of efficiency
η
threshhold
values calculated from the minimum required efficiency by subtracting a total tolerance
3.4.6
pump size
range of pumps characterized by certain dimensions (e.g. nominal diameter of discharge flange and
nominal impeller diameter for end-suction and multistage pumps, nominal outer casing diameter in the
case of submersible multistage pumps) and given in his catalogues by the manufacturer
Note 1 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 by 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.
3.4.7
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
3.4.8
best efficiency point
BEP
operating point where the greatest value of pumps efficiency is obtained, at nominal speed of rotation
3.4.9
part load
PL
particular operating point in the range of operating points with lower flow than best efficiency point, at
nominal speed of rotation
3.4.10
overload
OL
particular operating point in the range of operating points with higher flow than best efficiency point, at
nominal speed of rotation
4 Minimum Required Efficiencies and Minimum Efficiency Index
4.1 The concept of “house of efficiency”
To achieve the goal of energy saving by replacing less energy efficient pumps by pumps which are
qualified in respect to fulfilling criteria of minimum required efficiency, two important aspects have to
be taken into account:
a) The required minimum values of η shall be fulfilled by the mean values of the qualified pump
BEP
sizes which are produced and sold in large numbers. Therefore, these mean values shall be
determined by appropriate methods and then be compared to minimum required values 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 (see 4.2 and 4.3).
b) Not only the value of η is relevant for energy consumption and saving by pumps, but also the
BEP
efficiency 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 not 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.
ηη≥ (1)
( ) ( )
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:
B.
ηη≥ (2)
( ) ( )
PL PL
mean min,requ
(3)
ηη≥
( ) ( )
OL OL
mean min,requ
In this standard, 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 to fulfil
the criteria for qualification.
In Figure 2 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 2 — 'House of Efficiency' - explanatory representation
4.2 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 European Standard. The specific
-1
speed n of the pumps forming the data base ranges from 6 to 110,5 min and the range of flow rate at
s
best efficiency QBEP is from 1,8 to 1200 m /h. The performance data supplied by the European
manufacturers were 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 ) for each pump type and nominal speed within the scope. This correlation is
BEP s BEP
described by a mathematical formula (see below). 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 quadratic polynomial approximation are
BEP s BEP
presented in more detail in the final report of the evaluation study.
The mathematical formula describing the relation η = f (n , Q ) is:
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
( ( )) ( ( )) ( ) ( ) ( ) ( )
BEP s BEP s BEP s BEP
(4)
with
η in [%];
BEP
-1
n in [min ];
s
Q in [m³/h];
BEP
C: constant in [%], depending on Minimum Efficiency Index (MEI), see 4.4.
The result calculated from Formula (4) has to be rounded to the 1st digit after the decimal point.
The mathematical range of validity of the formula is:
-1 -1
6 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 1 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 lower limit.
NOTE 2 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, good cavitation performance, low noise and vibration levels.
Assuming that there are no other constraints, Formula (4) is valid for all pump types within the scope of
this European Standard pumping clean cold water. In the case of multistage pumps (MS), 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 equation is valid for the full impeller diameter of a pump size.
The efficiency values concern only pump efficiency, not the overall efficiency even in the case of close
coupled pump-motor units.
4.3 Minimum efficiency at part load and overload
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 defined by:
η η
PL OL
x = ; x = (5)
PL OL
η η
BEP BEP
were calculated for each pump type. The mean value of these coefficients were found to be x = 0,947
PL
and x = 0,985 for all pump types in good approximation.
OL
Using the relation described in 4.2 for η , the minimum efficiency requirements for the selected
BEP
operating points at part load and overload are
ηη0,947⋅ (6)
( ) ( )
PL BEP
min, requ min, requ
(η ) = 0,985⋅(η ) (7)
OL BEP
min,requ min,requ
4.4 Minimum Efficiency Index
By varying the constant C in the equation for η , the curves resulting from Formula (4) and plotted in a
BEP
n -η - diagram for constant values of Q are shifted in the vertical direction (see Figure 3 as an
s 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 yet and, therefore, 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, 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.
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. Therefore, values of MEI
higher than 0, 7 are not practically attainable for mass produced pumps.
NOTE 1 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 3 and 4.
-1
Figure 3 — Two-dimensional representation of ηBEP = f (ns,QBEP) for ESOB, n= 2 900 min and
MEI = 0,70 (see Table 3)
Figure 4 — ηBEP = f (ns) for ESOB with QBEP = 32 m³/h, 2 900 min-1 and for different values of
MEI (see Table 3)
For the choice of the value of MEI within the qualification procedure, the following applies:
a) 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.
b) Minimum values of MEI might be fixed by law, governmental 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 3
and 4. Figure 3 shows the principal dependence of η on the specific speed n and on the flow rate
min,requ s
at best efficiency Q . In Figure 4, the effect of varying the value of MEI on η is demonstrated.
BEP min,requ
In the frame of qualification or verification of a pump size, the values of Q and n - which η
BEP s min,requ
depends on - shall 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
BEP s
sample pumps is subjected to effects of manufacturing tolerances within the size (see Annex C) and of
measurement uncertainties (see Clause 5
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