EN ISO 9906:2012

Rotodynamic pumps - Hydraulic performance acceptance tests - Grades 1, 2 and 3 (ISO 9906:2012)

ISO 9906:2012 specifies hydraulic performance tests for customers' acceptance of rotodynamic pumps (centrifugal, mixed flow and axial pumps). It is intended to be used for pump acceptance testing at pump test facilities, such as manufacturers' pump test facilities or laboratories. ISO 9906:2012 can be applied to pumps of any size and to any pumped liquids which behave as clean, cold water.
It specifies three levels of acceptance:
grades 1B, 1E and 1U with tighter tolerance;
grades 2B and 2U with broader tolerance;
grade 3B with even broader tolerance.
It applies either to a pump itself without any fittings or to a combination of a pump associated with all or part of its upstream and/or downstream fittings.

Kreiselpumpen -Hydraulische Abnahmeprüfungen - Klassen 1, 2 und 3 (ISO 9906:2012)

Pompes rotodynamiques - Essais de fonctionnement hydraulique pour la réception - Niveaux 1, 2 et 3 (ISO 9906:2012)

L'ISO 9906:2012 spécifie les essais de performance hydraulique pour l'acceptation par les clients de pompes rotodynamiques (pompes centrifuges, hélico-centrifuges et hélices). Elle est destinée à être utilisée pour l'essai de réception des pompes dans des installations d'essai des pompes, comme les laboratoires ou les installations d'essai des pompes du fabricant. L'ISO 9906:2012 peut s'appliquer aux pompes quelle que soit leur taille et à tous les liquides pompés qui se comportent comme de l'eau froide propre.
Elle spécifie trois niveaux de réception:
niveaux 1B, 1E et 1U pour des tolérances les plus serrées;
niveaux 2B, 2U pour des tolérances plus larges;
niveau 3B pour des tolérances encore plus larges.
Elle est applicable soit à la pompe elle-même sans autre accessoire, soit à une combinaison associant une pompe à tout ou partie de ses accessoires en aval et/ou en amont.

Centrifugalne črpalke - Prevzemni preskus za hidravlične lastnosti - Razredi 1, 2 in 3 (ISO 9906:2012)

Ta mednarodni standard določa preskuse za hidravlične lastnosti za odobritev centrifugalnih črpalk (centrifugalne, mešane in aksialne črpalke, v nadaljnjem besedilu: črpalke) s strani stranke. Ta mednarodni standard je namenjen uporabi za preskuse za odobritev črpalk v objektih za preskušanje črpalk, na primer objektih za preskušanje črpalk ali laboratorijih proizvajalca. Uporablja se lahko za črpalke vseh velikosti in za vsako črpano tekočino, ki ima lastnosti čiste, mrzle vode. Ta mednarodni standard določa tri stopnje odobritve: – stopnje 1B, 1E in 1U z manjšo toleranco; – stopnji 2B in 2U z večjo toleranco; – stopnja 3B s še večjo toleranco. Ta mednarodni standard zadeva samo črpalko brez kakršne koli opreme ali črpalko v povezavi z vso ali delom njene opreme za uporabo proti toku in/ali v smeri toka.

General Information

• Status: Published
• Publication Date: 30-Apr-2012
• Withdrawal Date: 29-Nov-2012
• ICS: 23.080 - Pumps
• Technical Committee: CEN/TC 197 - Pumps
• Drafting Committee: CEN/TC 197 - Pumps
• Current Stage: 6060 - Definitive text made available (DAV) - Publishing
• Start Date: 01-May-2012
• Completion Date: 01-May-2012
• Ref Project: SIST EN ISO 9906:2012 - Rotodynamic pumps - Hydraulic performance acceptance tests - Grades 1, 2 and 3 (ISO 9906:2012)

Relations

• Replaces: EN ISO 9906:1999/AC:2004 - Rotodynamic pumps - Hydraulic performance acceptance tests - Grades 1 and 2 (ISO 9906:1999)
• Effective Date: 09-May-2012
• Replaces: EN ISO 9906:1999 - Rotodynamic pumps - Hydraulic performance acceptance tests - Grades 1 and 2 (ISO 9906:1999)
• Effective Date: 22-Dec-2008

Overview

EN ISO 9906:2012 - Rotodynamic pumps: Hydraulic performance acceptance tests specifies standardized procedures for verifying hydraulic performance of rotodynamic pumps (centrifugal, mixed‑flow and axial). Prepared by ISO/TC 115 and adopted by CEN, the standard is intended for pump test facilities (manufacturers’ test rigs or independent laboratories) and applies to pumps of any size handling liquids that behave like clean, cold water. Tests may be carried out on the pump alone or on the pump together with upstream/downstream fittings.

EN ISO 9906:2012 defines three acceptance levels (tolerance grades):

• Grades 1B, 1E, 1U - tighter tolerance
• Grades 2B, 2U - broader tolerance
• Grade 3B - broadest tolerance

Key topics and requirements

The standard covers practical and technical elements required for reliable acceptance testing:

• Scope and test arrangements - applicability to pump types, test facility setup and when fittings are included.
• Pump measurements and acceptance criteria - flow, head, power input and how results are compared to manufacturer guarantees.
• Measurement uncertainty - procedures to account for and report uncertainty in measured values.
• Test procedures - test programmes, date/conditions of testing, data acquisition and reporting requirements.
• NPSH testing - provisions and arrangements for Net Positive Suction Head tests (see informative annexes).
• Analysis and translation to guarantee conditions - converting test results to contract / guarantee points.
• Annexes for implementation - Instrumentation and calibration intervals, reporting formats, special methods (Annexes A–J include test arrangements, measurement equipment, calibration guidance, reporting and witness testing).
• Units and conversions - all formulae given in SI units; Annex I covers conversions.

Applications and practical value

EN ISO 9906:2012 is used to:

• Verify that a pump meets contractual performance guarantees before shipment.
• Standardize factory performance tests and independent laboratory testing.
• Reduce disputes between purchasers and manufacturers by providing clear acceptance classes and measurement uncertainty rules.
• Support quality control, production repeatability checks, impeller trim verification and final acceptance testing.

Who uses this standard

• Pump manufacturers and R&D/test engineers
• Pump test laboratories and independent third‑party testers
• Specifiers, EPC contractors and end‑users procuring pumps
• Quality assurance and commissioning teams

Related standards

• ISO 17769‑1 / ISO 17769‑2 (terms, definitions, quantities and symbols for liquid pumps and systems)
• Other ISO/CEN standards referenced within EN ISO 9906:2012 for instrumentation and measurement practice

Using EN ISO 9906:2012 ensures consistent, repeatable hydraulic performance acceptance testing and clear contractual acceptance criteria for rotodynamic pump projects.

Standards Content (Sample)

SLOVENSKI STANDARD
01-september-2012
1DGRPHãþD
SIST EN ISO 9906:2000
SIST EN ISO 9906:2000/AC:2006
&HQWULIXJDOQHþUSDONH3UHY]HPQLSUHVNXV]DKLGUDYOLþQHODVWQRVWL5D]UHGLLQ
,62
Rotodynamic pumps - Hydraulic performance acceptance tests - Grades 1, 2 and 3 (ISO
9906:2012)
Kreiselpumpen -Hydraulische Abnahmeprüfung - Klassen 1, 2 und 3 (ISO 9906:2012)
Pompes rotodynamiques - Essais de fonctionnement hydraulique pour la réception -
Niveaux 1, 2 et 3 (ISO 9906:2012)
Ta slovenski standard je istoveten z: EN ISO 9906:2012
ICS:
23.080 ýUSDONH Pumps
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN ISO 9906
NORME EUROPÉENNE
EUROPÄISCHE NORM
May 2012
ICS 23.080 Supersedes EN ISO 9906:1999
English Version
Rotodynamic pumps - Hydraulic performance acceptance tests -
Grades 1, 2 and 3 (ISO 9906:2012)
Pompes rotodynamiques - Essais de fonctionnement Kreiselpumpen -Hydraulische Abnahmeprüfung - Klassen
hydraulique pour la réception - Niveaux 1, 2 et 3 (ISO 1, 2 und 3 (ISO 9906:2012)
9906:2012)
This European Standard was approved by CEN on 16 March 2012.

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, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2012 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 9906:2012: E
worldwide for CEN national Members.

Contents Page
Foreword .3

Foreword
This document (EN ISO 9906:2012) has been prepared by Technical Committee ISO/TC 115 "Pumps" in
collaboration with 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 November 2012, and conflicting national standards shall be withdrawn
at the latest by November 2012.
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 supersedes EN ISO 9906:1999.
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, 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.
Endorsement notice
The text of ISO 9906:2012 has been approved by CEN as a EN ISO 9906:2012 without any modification.

INTERNATIONAL ISO
STANDARD 9906
Second edition
2012-05-01
Rotodynamic pumps — Hydraulic
performance acceptance tests —
Grades 1, 2 and 3
Pompes rotodynamiques — Essais de fonctionnement hydraulique pour
la réception — Niveaux 1, 2 et 3
Reference number
ISO 9906:2012(E)
©
ISO 2012
ISO 9906:2012(E)
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISO’s
member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail [e-mail]
Web www.iso.org
Published in Switzerland
ii © ISO 2012 – All rights reserved

ISO 9906:2012(E)
Contents Page
Foreword .iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms, definitions, symbols and subscripts . 1
3.1 Terms and definitions . 1
3.2 Terms relating to quantities . 3
3.3 Symbols and subscripts . 9
4 Pump measurements and acceptance criteria .10
4.1 General .10
4.2 Guarantees . 11
4.3 Measurement uncertainty . 11
4.4 Performance test acceptance grades and tolerances .15
4.5 Default test acceptance grades for pump application .21
5 Test procedures .22
5.1 General .22
5.2 Date of testing .22
5.3 Test programme .22
5.4 Testing equipment .22
5.5 Records and report .22
5.6 Test arrangements .23
5.7 Test conditions .23
5.8 NPSH tests .23
6 Analysis .26
6.1 Translation of the test results to the guarantee conditions .26
6.2 Obtaining specified characteristics .27
Annex A (normative) Test arrangements .28
Annex B (informative) NPSH test arrangements .37
Annex C (informative) Calibration intervals .40
Annex D (informative) Measurement equipment .41
Annex E (informative) Tests performed on the entire equipment set — String test .46
Annex F (informative) Reporting of test results .48
Annex G (informative) Special test methods .52
Annex H (informative) Witnessed pump test .53
Annex I (informative) Conversion to SI units .54
Annex J (informative) Measurement uncertainty for NPSH test .56
Bibliography .57
ISO 9906:2012(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International
Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 9906 was prepared by Technical Committee ISO/TC 115, Pumps, Subcommittee SC 2, Methods of
measurement and testing.
This second edition cancels and replaces the first edition (ISO 9906:1999), which has been technically revised.
iv © ISO 2012 – All rights reserved

ISO 9906:2012(E)
Introduction
The tests in this International Standard are intended to ascertain the performance of the pump and to compare
this with the manufacturer’s guarantee.
The nominated guarantee for any quantity is deemed to have been met if, where tested according to this International
Standard, the measured performance falls within the tolerance specified for the particular quantity (see 4.4).
INTERNATIONAL STANDARD ISO 9906:2012(E)
Rotodynamic pumps — Hydraulic performance acceptance
tests — Grades 1, 2 and 3
1 Scope
This International Standard specifies hydraulic performance tests for customers’ acceptance of rotodynamic
pumps (centrifugal, mixed flow and axial pumps, hereinafter “pumps”).
This International Standard is intended to be used for pump acceptance testing at pump test facilities, such as
manufacturers’ pump test facilities or laboratories.
It can be applied to pumps of any size and to any pumped liquids which behave as clean, cold water.
This International Standard specifies three levels of acceptance:
— grades 1B, 1E and 1U with tighter tolerance;
— grades 2B and 2U with broader tolerance;
— grade 3B with even broader tolerance.
This International Standard applies either to a pump itself without any fittings or to a combination of a pump
associated with all or part of its upstream and/or downstream fittings.
2 Normative references
The following referenced documents are indispensable for the application 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.
ISO 17769-1, Liquid pumps and installation — General terms, definitions, quantities, letter symbols and units —
Part 1: Liquid pumps
ISO 17769-2, Liquid pumps and installation — General terms, definitions, quantities, letter symbols and units —
Part 2: Pumping system
3 Terms, definitions, symbols and subscripts
3.1 Terms and definitions
For the purposes of this document, the terms, definitions, quantities and symbols given in ISO 17769-1 and
17769-2 and the following apply.
NOTE 1 Table 1 gives an alphabetical list of the symbols used and Table 2 gives a list of subscripts; see 3.3.
NOTE 2 All formulae are given in coherent SI units. For conversion of other units to SI units, see Annex I.
3.1.1 General terms
NOTE All of the types of test in 3.1.1 apply to guarantee point to fulfil the customer’s specification(s).
3.1.1.1
guarantee point
flow/head (Q/H) point, which a tested pump shall meet, within the tolerances of the agreed acceptance class
ISO 9906:2012(E)
3.1.1.2
factory performance test
pump test performed to verify the initial performance of new pumps as well as checking for repeatability of
production units, accuracy of impeller trim calculations, performance with special materials, etc.
NOTE A typical performance test consists of the measurement of flow, head and power input to the pump or pump
test motor. Additional measurements, such as NPSH, may be included as agreed upon. A factory test is understood to
mean testing at a dedicated test facility, often at a pump manufacturer’s plant or at an independent pump test facility.
3.1.1.3
non-witnessed pump test
3.1.1.3.1
factory test
test performed without the presence of a purchaser’s representative, in which the pump manufacturer is
responsible for the data collection and judgement of pump acceptance
NOTE The advantage of this test is cost savings and accelerated pump delivery to the pump user. In many cases, if
the purchaser is familiar with the performance of the pump (e.g. identical pump model order), a factory non-witnessed test
may be acceptable.
3.1.1.3.2
signed factory test
test performed without the presence of a purchaser’s representative, in which the pump manufacturer is
responsible for compliance with the parameters of the agreed acceptance class
NOTE The pump manufacturer conducts the test, passes judgement of pump acceptance and produces a signed
pump test document. The advantage of this test is the same as seen on the non-witnessed test. Compared to a witnessed
test, this test is substantially less expensive and often leads to accelerated pump delivery to the end user.
3.1.1.4
witnessed pump test
NOTE The witnessing of a pump test by a representative of the pump purchaser can serve many useful functions.
There are various ways of witnessing a test.
3.1.1.4.1
witnessing by the purchaser’s representative
testing physically attended by a representative of the purchaser, who signs off on the raw test data to certify
that the test is performed satisfactorily
NOTE It is possible for final acceptance of the pump performance to be determined by the witness. The benefit of
witness testing depends largely on the effectiveness and expertise of the witness. A witness cannot only ensure the test
is conducted properly, but also observes operation of the pump during testing prior to pump shipment to the job site. A
disadvantage of witness testing can be extended delivery times and excessive cost. With just-in-time manufacturing
methods, the scheduling of witness testing requires flexibility on the part of the witness and can lead to additional costs if
the schedule of the witness causes delays in manufacturing.
3.1.1.4.2
remote witnessing by the purchaser’s representative
pump performance testing witnessed from a distance by the purchaser or his/her representative
NOTE With a remote camera system, the purchaser can monitor the entire testing remotely in real-time. The raw
data, as recorded by the data acquisition system, can be viewed and analysed during the test, and the results can be
discussed and submitted for approval. The advantages of this type of testing are savings in travel costs and accelerated
pump delivery.
2 © ISO 2012 – All rights reserved

ISO 9906:2012(E)
3.2 Terms relating to quantities
3.2.1
angular velocity
ω
number of radians of shaft rotation
NOTE 1 It is given by:
ω =2πn (1)
-1 -1
NOTE 2 It is expressed in time, e.g. s , where n is given in 60 × min .
3.2.2
speed of rotation
number of rotations per second
3.2.3
mass flow rate
rate of flow discharged into the pipe from the outlet connection of the pump
NOTE 1 The mass flow rate is given in kilograms per second.
NOTE 2 The following losses or limiting effects are inherent to the pump:
a) discharge necessary for hydraulic balancing of axial thrust;
b) cooling of the pump bearings.
NOTE 3 Leakage from the fittings, internal leakage, etc., are not to be reckoned in the rate of flow. On the contrary, all
derived flows for other purposes, such as
a) cooling of the motor bearings, and
b) cooling of a gear box (bearings, oil cooler)
are to be reckoned in the rate of flow.
NOTE 4 Whether and how these flows should be taken into account depends on the location of their derivation and of
the section of flow-measurement respectively.
3.2.4
volume rate of flow
rate of flow at the outlet of the pump, given by:
q
Q = (2)
ρ
NOTE In this International Standard, this symbol may also designate the volume rate of flow in any given section. It
is the quotient of the mass rate of flow in this section by the density. (The section may be designated by subscripts.)
3.2.5
mean velocity
mean value of the axial speed of flow, given by:
Q
U = (3)
A
NOTE Attention is drawn to the fact that in this case, Q may vary for different reasons across the circuit.
3.2.6
local velocity
speed of flow at any given point
ISO 9906:2012(E)
3.2.7
head
energy of mass of liquid, divided by acceleration due to gravity, g, given by:
y
H= (4)
g
See 3.2.16.
3.2.8
reference plane
any horizontal plane used as a datum for height measurement
NOTE For practical reasons, it is preferable not to specify an imaginary reference plane.
3.2.9
height above reference plane
height of the considered point above the reference plane
See Figure A.1.
NOTE Its value is:
— positive, if the considered point is above the reference plane;
— negative, if the considered point is below the reference plane.
3.2.10
gauge pressure
pressure relative to atmospheric pressure
NOTE 1 Its value is:
— positive, if this pressure is greater than the atmospheric pressure;
— negative, if this pressure is less than the atmospheric pressure.
NOTE 2 All pressures in this International Standard are gauge pressures read from a manometer or similar pressure sensing
instrument, except atmospheric pressure and the vapour pressure of the liquid, which are expressed as absolute pressures.
3.2.11
velocity head
kinetic energy of the liquid in movement, divided by g, given by:
U
(5)
2g
3.2.12
total head
overall energy in any section
NOTE 1 The total head is given by:
p U
xx
Hz=+ + (6)
xx
ρ×g 2×g
where
z is the height of the centre of the cross-section above the reference plane;
p is the gauge pressure related to the centre of the cross-section.
NOTE 2 The absolute total head in any section is given by:
4 © ISO 2012 – All rights reserved

ISO 9906:2012(E)
p p U
xxamb
Hz=+ + + (7)
xx(abs)
ρρ×g ×g 2g
3.2.13
inlet total head
overall energy at the inlet section of the pump
NOTE Inlet total head is given by:
p U
Hz=+ + (8)
ρ×g 2g
3.2.14
outlet total head
overall energy at the outlet section of the pump
NOTE Outlet total head is given by:
p
U
2 2
Hz=+ + (9)
ρ×g 2g
3.2.15
pump total head
algebraic difference between the outlet total head, H , and the inlet total head, H
2 1
NOTE 1 If compressibility is negligible, H = H − H . If the compressibility of the pumped liquid is significant, the density,
2 1
ρ, should be replaced by the mean value:
ρρ+
ρ = (10)
m
and the pump total head should be calculated by Formula (12):
2 2
pp− UU−
21 2 1
Hz=−z + + (11)
ρ ⋅ g 2g
m
NOTE 2 The correct mathematical symbol is H .
12−
3.2.16
specific energy
energy of liquid, given by:
yg= H (12)
3.2.17
loss of head at inlet
difference between the total head of the liquid at the measuring point and the total head of the liquid in the inlet
section of the pump
3.2.18
loss of head at outlet
difference between the total head of the liquid in the outlet section of the pump and the total head of the liquid
at the measuring point
3.2.19
pipe friction loss coefficient
coefficient for the head loss by friction in the pipe
ISO 9906:2012(E)
3.2.20
net positive suction head
NPSH
absolute inlet total head above the head equivalent to the vapour pressure relative to the NPSH datum plane
NOTE 1 NPSH is given by:
pp−
amb v
NPSH =−Hz + (13)
1 D
ρ ⋅ g
NOTE 2 This NPSH relates to the NPSH datum plane, whereas inlet total head relates to the reference plane.
NOTE 3 A derogation has been given to allow the use of the abbreviated term NPSH (upright and not bold) as a symbol
in mathematical formulae as a consequence of its well-established, historical use in this manner.
3.2.20.1
NPSH datum plane
horizontal plane through the centre of the circle described by the external points of the
entrance edges of the impeller blades
3.2.20.2
NPSH datum plane
plane through the higher centre
See Figure 1.
NOTE It is the responsibility of the manufacturer to indicate the position of this plane with respect to precise reference
points on the pump.
Key
1 NPSH datum plane
Figure 1 — NPSH datum plane
3.2.21
available NPSH
NPSHA
NPSH available as determined by the conditions of the installation for a specified rate of flow
NOTE A derogation has been given to allow the use of the abbreviated term NPSHA (upright and not bold) as a
symbol in mathematical formulae as a consequence of its well-established, historical use in this manner.
3.2.22
required NPSH
NPSHR
minimum NPSH given by the manufacturer for a pump achieving a specified performance at the specified
rate of flow, speed and pumped liquid (occurrence of visible cavitation, increase of noise and vibration due
to cavitation, beginning of head or efficiency drop, head or efficiency drop of a given amount, limitation of
cavitation erosion)
NOTE A derogation has been given to allow the use of the abbreviated term NPSHR (upright and not bold) as a
symbol in mathematical formulae as a consequence of its well-established, historical use in this manner.
6 © ISO 2012 – All rights reserved

ISO 9906:2012(E)
3.2.23
NPSH3
NPSH required for a drop of 3 % of the total head of the first stage of the pump as standard basis for use in
performance curves
NOTE A derogation has been given to allow the use of the abbreviated term NPSH (upright and not bold) as a symbol
in mathematical formulae as a consequence of its well-established, historical use in this manner.
3.2.24
type number
dimensionless quantity calculated at the point of best efficiency
NOTE 1 It is given by:
12/ 12/
2πωnQ ′ Q′
K == (14)
34/ 34/
()gH′ y′
where
Q′ is the volume rate of flow per eye;
H′ is the head of the first stage;
-1
n is given in s .
NOTE 2 The type number is to be taken at maximum diameter of the first stage impeller.
3.2.25
pump power input
P
power transmitted to the pump by its driver
3.2.26
pump power output
hydraulic power at the pump discharge
NOTE Pump power output is given by:
PQ==ρρgH Qy (15)
h
3.2.27
driver power input
P
gr
power absorbed by the pump driver
3.2.28
maximum shaft power
P
2,max
maximum pump shaft power, as set by the manufacturer, which is adequate to drive the pump over the specified
operating conditions
3.2.29
pump efficiency
pump power output divided by the pump power input
NOTE Pump efficiency is given by:
P
h
η = (16)
P
ISO 9906:2012(E)
3.2.30
overall efficiency
pump power output divided by the driver power input
NOTE Overall efficiency is given by:
P
h
η = (17)
gr
P
gr
8 © ISO 2012 – All rights reserved

ISO 9906:2012(E)
3.3 Symbols and subscripts
Table 1 — Alphabetical list of basic letters used as symbols
Symbol Quantity Unit
A Area m
D Diameter m
e Overall uncertainty, relative value %
−1
f
Frequency s , Hz
a 2
g
Acceleration due to gravity m/s
H
Pump total head m
H Losses in terms of head of liquid m
J
k Equivalent uniform roughness m
K Type number Pure number
l Length m
M Torque Nm
−1 −1
n Speed of rotation s , min
NPSH Net positive suction head m
p Pressure Pa
P Power W
b
q Mass flow rate kg/s
c 3
Q (Volume) rate of flow m /s
Re Reynolds number Pure number
τ Tolerance factor, relative value %
t Students distribution Pure number
U Mean velocity m/s
v
Local velocity m/s
V
Volume m
y Specific energy J/kg
z Height above reference plane m
z Difference between NPSH datum plane and reference plane (see 3.2.20) m
D
η Efficiency Pure number
θ Temperature °C
λ Pipe friction loss coefficient Pure number
ν Kinematic viscosity m /s
ρ Density kg/m
ω Angular velocity rad/s
a 2
In principle, the local value of g should be used. Nevertheless, for grades 2 and 3, it is sufficient to use a value of 9,81 m/s . For
2 −6
the calculation of the local value g = 9,780 3 (1 + 0,005 3 sin ϕ) − 3 × 10 ⋅ Z, where ϕ is the latitude and Z is the height above sea
level.
b
An optional symbol for mass flow rate is q .
m
c
An optional symbol for volume rate of flow is q .
v
ISO 9906:2012(E)
Table 2 — List of letters and figures used as subscripts
Subscript Meaning
1 inlet
1′ inlet measuring section
2 outlet (except for P )
2′ outlet measuring section
abs absolute
amb ambient
D difference, datum
f liquid in measuring pipes
G guaranteed
H pump total head
h hydraulic
gr combined motor/pump unit (overall)
J losses
M manometer
n speed of rotation
P power
Q (volume) rate of flow
ref reference plane
sp specified
T translated, torque
v vapour (pressure)
η efficiency
x at any section
4 Pump measurements and acceptance criteria
4.1 General
The specified and contractually agreed upon rated point (duty point), hereinafter “the guarantee point”, shall be
evaluated against one acceptance grade and its corresponding tolerance. For a pump performance test, this
guarantee point shall always specify the guaranteed flow, Q , and guaranteed head, H , and may, optionally,
G G
specify guaranteed efficiency, guaranteed shaft power or guaranteed net positive suction head required
(NPSHR). Where applicable, these optional guarantee parameters need to be specified for those tests, see
respective tests in 4.4.3 and 5.8.
The acceptance grade tolerance applies to the guarantee point only. Other specified duty points, including their
tolerances, shall be by separate agreement between the manufacturer and purchaser. If other specified duty
points are agreed upon, but no tolerance is given for these points, the default acceptance level for these points
shall be grade 3.
A guarantee point may be detailed in a written contract, a customer-specific pump performance curve or similar
written and project specific documentation.
If not otherwise agreed upon between the manufacturer and the purchaser, the following shall apply.
a) The acceptance grade shall be in accordance with the grades given in Table 8.
10 © ISO 2012 – All rights reserved

ISO 9906:2012(E)
b) Tests shall be carried out on the test stand of the manufacturer’s works with clean, cold water using the
methods and test arrangements specified in this International Standard.
c) The pump performance shall be guaranteed between the pump’s inlet connection and outlet connection.
d) Pipe and fittings (bends, reducers and valves) outside of the pump are not a part of the guarantee.
The combination of manufacturing and measurement tolerances in practice necessitates the usage of tolerances on
tested values. The tolerances given in Table 8 take into account both manufacturing and measurement tolerances.
The performance of a pump varies substantially with the nature of the liquid being pumped. Although it is not
possible to give general rules whereby performance with clean, cold water can be used to predict performance
with other liquids, it is desirable for the parties to agree on empirical rules to suit the particular circumstances.
For further information, see ISO/TR 17766.
If a number of identical pumps are being purchased, the number of pumps to be tested shall be agreed between
the purchaser and manufacturer.
Both the purchaser and manufacturer shall be entitled to witness the testing. If tests are not carried out
at the manufacturer’s test stand, opportunity shall be allowed for verification of the pump installation and
instrumentation adjustments by both parties.
4.2 Guarantees
The manufacturer guarantees that, for the guarantee point and at the rated speed (or in some cases frequency
and voltage), the measured pump curve touches, or passes through a tolerance surrounding the guarantee
point, as defined by the applicable acceptance grade (see Table 8 and Figures 2 and 3).
A guarantee point shall be defined by a guaranteed flow, Q , and a guaranteed head, H .
G G
In addition, one or more of the following quantities may be guaranteed at the specified conditions and at
the rated speed:
a) as defined in 4.4.3 and Figures 4, 5 and 6,
1) the minimum pump efficiency, η , or the maximum pump input power, P , or
G G
2) in the case of a combined pump and motor unit, the minimum combined efficiency, η , or the
grG
maximum pump motor unit input power, P .
grG
b) the maximum NPSHR at the guarantee flow.
The maximum power input may be guaranteed for the guarantee point or for a range of points along the
pump curve. This, however, can require larger tolerances to be agreed upon between the purchaser and
manufacturer.
4.3 Measurement uncertainty
4.3.1 General
Every measurement is inevitably subject to some uncertainty, even if the measuring procedures and the
instruments used, as well as the methods of analysis, fully comply with good practice and with the requirements
of this International Standard.
The guidance and procedures described in 4.3.2 and 4.3.3 are intended to provide general information to the
user, as well as practical procedures allowing the user to estimate measurement uncertainty with reasonable
confidence in applying the testing in conformity with this International Standard.
NOTE For comprehensive information on measurement uncertainty, see ISO/IEC Guide 99 and associated documents.
ISO 9906:2012(E)
4.3.2 Fluctuations
Where the design or operation of a pump is such that fluctuations of great amplitude are present, measurements
may be carried out by providing a damping device in the measuring instruments or their connecting lines, which
is capable of reducing the amplitude of the fluctuations to within the values given in Table 3. A symmetrical and
linear damping device shall be used, for example a capillary tube, which shall provide integration over at least
one complete cycle of fluctuations.
Table 3 — Permissible amplitude of fluctuation as a percentage of mean value of quantity being
measured
Permissible amplitude of fluctuations
Grade 1 Grade 2 Grade 3
Measured quantity
% % %
Rate of flow ±2 ±3 ±6
Differential head ±3 ±4 ±10
Outlet head ±2 ±3 ±6
Inlet head ±2 ±3 ±6
Input power ±2 ±3 ±6
Speed of rotation ±0,5 ±1 ±2
Torque ±2 ±3 ±6
Temperature 0,3 °C 0,3 °C 0,3 °C
4.3.3 Statistical evaluation of overall measurement uncertainty
4.3.3.1 The estimate of the random component (random uncertainty)
The random component due either to the characteristics of the measuring system or to variations of the
measured quantity or both appears directly as a scatter of the measurements. Unlike the systematic uncertainty,
the random component can be reduced by increasing the number of measurements of the same quantity under
the same conditions.
A set of readings not less than three (3) shall be taken at each test point. The random component, e , shall be
R
calculated as follows:
The estimate of the random component of measurement uncertainty is calculated from the mean and the
standard deviation of the observations. For the uncertainty of the readings, replace x with the actual measurement
readings of flow, Q, head, H, and power, P.
12 © ISO 2012 – All rights reserved

ISO 9906:2012(E)
If n is the number of readings, the arithmetic mean, x, of a set of repeated observations x (in= 1. ) is
i
x = x (18)
∑ i
n
The standard deviation, s, of these observations is given by:
s = ()xx−
(19)
∑ i
n−1
The relative value of the uncertainty, e , of the mean due to random effects is given by:
R
100ts
e = % (20)
R
xn
where t is a function of n as given in Table 4.
NOTE 1 If the value of the overall uncertainty, e, does not meet the criteria given in Table 7, the value of the random
component, e , of the measurement can be reduced by increasing the number of measurements of the same quantity
R
under the same conditions.
NOTE 2 The random component, as defined in this International Standard, is classified as Type A uncertainty (see
ISO/IEC Guide 99).
Table 4 — Values of Student’s t-distribution
(based on 95 % confidence level)
n t n t
3 4,30 12 2,20
4 3,18 13 2,18
5 2,78 14 2,16
6 2,57 15 2,14
7 2,45 16 2,13
8 2,36 17 2,12
9 2,31 18 2,11
10 2,26 19 2,10
11 2,23 20 2,09
4.3.3.2 The estimate of the instrumental measurement uncertainty (systematic uncertainties)
After all known errors have been removed by zero adjustment, calibration, careful measurement of dimensions,
proper installation, etc., there remains an uncertainty which never disappears. This uncertainty cannot be reduced
by repeating the measurements if the same instrument and the same method of measurement are used.
The estimate of the systematic uncertainty of the uncertainty, e , is in practice based on calibration traceable
S
to international measurement standards. Permissible relative values for the systematic uncertainty in this
International Standard are given in Table 5.
ISO 9906:2012(E)
Table 5 — Permissible relative values of the instrumental uncertainty, e
S
Maximum permissible systematic uncertainty
(at guarantee point)
Measured quantity
Grade 1 Grades 2 and 3
% %
Rate of flow ±1,5 ±2,5
Differential head ±1,0 ±2,5
Outlet head ±1,0 ±2,5
Inlet head ±1,0 ±2,5
a
Suction head for NPSH testing ±0,5 ±1,0
Driver power input ±1,0 ±2,0
Speed of rotation ±0,35 ±1,4
Torque ±0,9 ±2,0
a
See Annex J for explanation.
4.3.3.3 The overall uncertainty
The value for overall uncertainty, e, is given by:
ee=+ e (21)
RS
Permissible values of overall measurement uncertainties, e, are given in Table 6.
NOTE The overall uncertainty, as defined in this International Standard, is equated with expanded measurement
uncertainty (see ISO/IEC Guide 99).
Table 6 — Permissible values of overall uncertainties
Quantity Symbol Grade 1 Grades 2, 3
% %
Flow rate e ±2,0 ±3,5
Q
Speed of rotation e ±0,5 ±2,0
n
Torque e ±1,4 ±3,0
T
Pump total head e ±1,5 ±3,5
H
Driver power input e ±1,5 ±3,5
Pgr
Pump power input (computed from
e
±1,5 ±3,5
P
torque and speed of rotation)
Pump power input (computed from
e ±2,0 ±4,0
P
driver power and motor efficiency)
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ISO 9906:2012(E)
4.3.3.4 Determination of overall uncertainty of efficiency
The overall uncertainty of the overall efficiency and of the pump efficiency is calculated using Formulae (22),
(24) and (25):
22 2
e = ee++e (22)
ηgr
QH Pgr
if efficiency is computed from torque and speed of rotation:
22 22
e = ee++ee+ (23)
η
QH T n
if efficiency is computed from pump power input:
22 2
e = ee++e (24)
η
QH P
Using the values given in Table 6, the calculations lead to the results given in Table 7.
Table 7 — Resulting greatest values of the overall uncertainties of efficiency
Quantity Symbol Grade 1 Grades 2 and 3
% %
Overall efficiency (computed from Q, H, P ) e ±2,9 ±6,1
gr ηgr
Pump efficiency (computed from Q, H, M, n) e ±2,9 ±6,1
η
Pump efficiency (computed from Q, H, P , η ) e ±3,2 ±6,4
gr mot η
4.4 Performance test acceptance grades and tolerances
4.4.1 General
Six pump performance test acceptance grades, 1B, 1E, 1U, 2B, 2U and 3B are defined in this subclause.
Grade 1 is the most stringent grade, with 1U and 2U having a unilateral tolerance and grades 1B, 2B and
3B having a bilateral tolerance. Grade 1E is also bilateral in nature and is important to those concerned with
energy efficiency.
NOTE The grades 1U, 1E and 1B have the same tolerance for flow and head.
The purchaser and manufacturer may agree to use any grade to judge whether or not a specific pump meets
a guarantee point. If a guarantee point is given, but no acceptance grade is specified, this standard reverts to
a default test acceptance grade, as described in 4.5.
Guarantee point acceptance grades for pump head, flow, power and efficiency are provided in Table 8. All
tolerances are percentages of values guaranteed.
ISO 9906:2012(E)
Table 8 — Pump test acceptance grades and corresponding tolerance
Grade 1 2 3
Δτ 10 % 16 % 18 %
Q
Guarantee
requirement
Δτ 6 % 10 % 14 %
H
Acceptance grade 1U 1E 1B 2B 2U 3B
τ +10 % ±5 % ±8 % +16 % ±9 %
Q
Mandatory
τ +6 % ±3 % ±5 % +10 % ±7 %
H
τ +10 % +4 % +8 % +16 % +9 %
P
Optional
τ ≥0 % −3 % −5 % −7 %
η
NOTE τ (x = Q, H, P, η) stands for the tolerance of the indicated quantity.
x
4.4.2 Tolerances for pumps with an input power of 10 kW and below
For pumps with shaft power input of below 10 kW, the tolerance factors given in Table 8 can be too stringent.
If not otherwise agreed upon between the manufacturer and purchaser, the tolerance factors shall be the following:
— rate of flow τ = ±10 %;
Q
— pump total head τ = ±8 %.
H
The tolerance factor on efficiency, τ , if guaranteed, shall be calculated as given by Formula (25):
η
P
 
τ =− 10()1 −+7 % (25)
η  
 
where the pump power input, P , tallies with the maximum shaft power (input), P , in kilowatts, over the
2 2,max
range of operation. A tolerance factor, τ ,is allowed using Formula (26):
P,gr
ττ=+()7 % (26)
P,gr η
4.4.3 Evaluation of flow and head
Guarantee point evaluation shall be performed at the rated speed. Test points do not have to be recalculated
based on speed in cases where the test speed is identical to the rated speed and for tests with a combined
motor and pump (i.e. submersible pumps, close-coupled pumps and all pumps tested with the motor which are
installed with the pump). For tests in which the test speed is different from the rated speed, each test point shall
be recalculated to the rated speed, using the affinity laws.
The tolerances for flow and head shall be applied in the following manner.
— The pump flow tolerance shall be applied to the guaranteed flow, Q , at the guaranteed head, H ;
G G
— The pump head tolerance shall be applied to the guaranteed head, H , at the guaranteed flow, Q .
G G
Acceptance is achieved if either flow or head, or both, are found to be within the applicable tolerance (see
Figures 2 and 3).
16 © ISO 2012 – All rights reserved

ISO 9906:2012(E)
Key
X rate of flow, Q
Y head, H
curve 1: crosses the head tolerance, P = pass
curve 2: crosses the flow tolerance, P = pass
curve 3: crosses both the head and flow tolerance, P = pass
curve 4: does not cross any tolerance, F = fail
curve 5: does not cross any tolerance, F = fail
Figure 2 — Uni-lateral tolerance acceptance
ISO 9906:2012(E)
Key
X rate of flow, Q
Y head, H
curve 1: crosses the head tolerance, P = pass
curve 2: crosses the flow tolerance, P = pass
curve 3: crosses both the head and flow tolerance, P = pass
curve 4: does not cross any tolerance, F = fail
curve 5: does not cross any tolerance, F = fail
Figure 3 — Bi-lateral tolerance acceptance
4.4.4 Evaluation of efficiency or power
If efficiency or power has been guaranteed, it shall be evaluated against the applicable acceptance grade
tolerance factor, i.e. the same as for Q/H in the following manner:
After a best-fit test curve (Q-H-/Q-η/ or Q-P-curves) is drawn and smoothly
...