SIST EN 17694-2:2023
(Main)Hydrometry - Minimum performance requirements and test procedures for water monitoring equipment - Devices for the determination of flow - Part 2: Closed conduit instrumentation
Hydrometry - Minimum performance requirements and test procedures for water monitoring equipment - Devices for the determination of flow - Part 2: Closed conduit instrumentation
This European standard specifies general requirements, minimum performance requirements and test procedures forinstrumentation used to measure either volumetric flow-rate and/or total volume passed of water in closed conduits. It covers all closed conduit instrument (CCI) technologies intended to operate in closed pressurised pipes and partially filled pipes.
It is recognised that for some CCIs certain tests cannot be carried out.
The data obtained from the testing of CCIs in accordance with the requirements of the Measuring Instruments Directive [4] or ISO4064-1 [5] can be used to meet, in part, the requirements specified in this European Standard. However, for the avoidance of doubt,compliance with the requirements of this European Standard does not equate to compliance with the requirements of theMeasuring Instruments Directive or ISO 4064-1.
Hydrometrie - Leistungsanforderungen und Prüfverfahren für Wasserüberwachungsgeräte - Geräte zur Bestimmung des Durchflusses - Teil 2: Messgeräte für geschlossene Rohrleitungen
Dieses Dokument legt allgemeine Anforderungen, Mindest-Leistungsanforderungen und Prüfverfahren für Messgeräte fest, die für die Messung des Volumenstroms und/oder des Gesamtdurchflussvolumens von Wasser in geschlossenen Rohrleitungen verwendet werden. Es deckt alle Technologien für Messgeräte für geschlossene Rohrleitungen (CCIs) ab, die für den Betrieb in geschlossenen Druckleitungen und teilgefüllten Rohren vorgesehen sind. Die Anforderungen werden als Volumeneinheiten angegeben, die anhand der Flüssigkeitsdichte in eine Masse umgerechnet werden können.
Es ist bekannt, dass bestimmte Prüfungen für einige CCIs nicht durchgeführt werden können.
Die bei der Prüfung von CCIs in Übereinstimmung mit den Anforderungen der Messgeräterichtlinie [1] oder den Anforderungen nach EN ISO 4064-1 [2] gewonnenen Daten können teilweise verwendet werden, um die Einhaltung der in diesem Dokument festgelegten Anforderungen nachzuweisen. Zur Klarstellung wird jedoch darauf hingewiesen, dass die Einhaltung der Anforderungen dieses Dokuments nicht mit der Einhaltung der Anforderungen der Messgeräterichtlinie oder der Anforderungen nach EN ISO 4064-1 gleichgesetzt werden kann.
Hydrométrie - Exigences minimales de performance et modes opératoires d'essai pour les équipements de surveillance de l'eau - Dispositifs de mesure de l'écoulement - Partie 2 : Instruments de mesure pour écoulements en conduite fermée
Le présent document spécifie les exigences générales, les exigences minimales de performance et les modes opératoires d'essai applicables aux instruments utilisés pour mesurer le débit volumétrique et/ou le volume total passé d'eau dans les conduites fermées. Il couvre toutes les technologies d'instruments de mesure pour écoulements en conduite fermée (CCI) destinées à fonctionner dans des tuyaux sous pression fermés et des tuyaux partiellement remplis. Les exigences sont exprimées en unités volumétriques qui peuvent être converties en masse à l'aide de la densité de l'eau.
Il est reconnu que certains essais ne peuvent pas être effectués sur certains CCI.
Les données obtenues à partir des essais des CCI conformément aux exigences de la Directive Instruments de mesure [1] ou de l'EN ISO 4064-1 [2] peuvent être utilisées pour répondre, en partie, aux exigences spécifiées dans le présent document. Toutefois, pour éviter tout doute, le respect des exigences du présent document n'équivaut pas au respect des exigences de la Directive Instruments de mesure ou de l'EN ISO 4064-1.
Hidrometrija - Minimalne zahteve za tehnične lastnosti in preskusni postopki za opremo za nadzor vode - Naprave za ugotavljanje pretoka - 2. del: Instrumenti za merjenje v zaprtem vodu
Ta evropski standard določa splošne zahteve, minimalne zahteve glede zmogljivosti in preskusne postopke za instrumente, ki se uporabljajo za merjenje stopnje volumetričnega pretoka in/ali celotne količine pretoka vode v umetno zaprtih vodih. Zajema vse tehnologije instrumentov za merjenje v zaprtem vodu (CCI), ki so namenjene za delovanje v zaprtih ceveh pod tlakom in delno napolnjenih ceveh.
Znano je, da nekaterih preskusov instrumentov za merjenje v zaprtem vodu ni mogoče izvesti.
Podatke, pridobljene pri preskušanju instrumentov za merjenje v zaprtem vodu v skladu z zahtevami Direktive o merilnih instrumentih [4] ali standarda ISO 4064-1 [5], je mogoče deloma uporabiti za izpolnjevanje zahtev, določenih v tem evropskem standardu. V izogib dvomom skladnost z zahtevami tega evropskega standarda ni enaka skladnosti z zahtevami Direktive o merilnih instrumentih ali standarda ISO 4064-1.
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN 17694-2:2023
01-julij-2023
Hidrometrija - Minimalne zahteve za tehnične lastnosti in preskusni postopki za
opremo za nadzor vode - Naprave za ugotavljanje pretoka - 2. del: Instrumenti za
merjenje v zaprtem vodu
Hydrometry - Minimum performance requirements and test procedures for water
monitoring equipment - Devices for the determination of flow - Part 2: Closed conduit
instrumentation
Hydrometrie - Leistungsanforderungen und Prüfverfahren für
Wasserüberwachungsgeräte - Geräte zur Bestimmung des Durchflusses - Teil 2:
Messgeräte für geschlossene Rohrleitungen
Hydrométrie - Exigences minimales de performance et modes opératoires d'essai pour
les équipements de surveillance de l'eau - Dispositifs de mesure de l'écoulement - Partie
2 : Instruments de mesure pour écoulements en conduite fermée
Ta slovenski standard je istoveten z: EN 17694-2:2023
ICS:
07.060 Geologija. Meteorologija. Geology. Meteorology.
Hidrologija Hydrology
17.120.10 Pretok v zaprtih vodih Flow in closed conduits
SIST EN 17694-2:2023 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN 17694-2:2023
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SIST EN 17694-2:2023
EN 17694-2
EUROPEAN STANDARD
NORME EUROPÉENNE
May 2023
EUROPÄISCHE NORM
ICS 17.120.10
English Version
Hydrometry - Minimum performance requirements and
test procedures for water monitoring equipment - Devices
for the determination of flow - Part 2: Closed conduit
instrumentation
Hydrométrie - Exigences minimales de performance et Hydrometrie - Leistungsanforderungen und
modes opératoires d'essai pour les équipements de Prüfverfahren für Wasserüberwachungsgeräte - Geräte
surveillance de l'eau - Dispositifs de mesure de zur Bestimmung des Durchflusses - Teil 2: Messgeräte
l'écoulement - Partie 2 : Instruments de mesure pour für geschlossene Rohrleitungen
écoulements en conduite fermée
This European Standard was approved by CEN on 13 February 2023.
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, Türkiye 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
© 2023 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 17694-2:2023 E
worldwide for CEN national Members.
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SIST EN 17694-2:2023
EN 17694-2:2023 (E)
Contents Page
European foreword . 4
Introduction . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Symbols . 8
5 Principle . 9
6 General requirements . 10
6.1 Requirements for closed conduit instrumentation . 10
6.2 Requirements for associated documentation . 11
7 Performance requirements . 12
7.1 Expression of performance requirements . 12
7.2 Performance requirements . 13
7.3 Data retention . 14
7.4 Environmental requirements . 14
7.5 Water temperature requirements . 14
7.6 Installation influences . 14
7.7 Field test requirements . 14
8 Testing . 15
8.1 General requirements for testing . 15
8.2 Laboratory test conditions . 15
8.3 Reporting . 17
9 Laboratory test procedures . 17
9.1 Guidance for establishing a test plan . 17
9.2 Verification by inspection . 20
9.3 Performance tests . 20
9.3.1 Loss of power for electronic CCIs . 20
9.3.2 Bias and repeatability . 20
9.3.3 Supply voltage . 21
9.3.4 Output impedance . 22
9.3.5 Water temperature . 22
9.3.6 Ambient air temperature and relative humidity . 22
9.3.7 Sensor location . 23
9.3.8 Presence of stray currents . 24
9.3.9 Bi-directional flow . 25
9.3.10 Flow reversal . 25
9.3.11 Ancillary devices . 25
9.3.12 Effect of conduit material . 26
9.3.13 Effect of conduit size . 26
9.3.14 Fill level. 27
9.3.15 Response time . 27
10 Field test procedures . 28
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SIST EN 17694-2:2023
EN 17694-2:2023 (E)
10.1 Objective of field test . 28
10.2 Field test plan . 28
10.3 Field test requirements . 28
10.4 Error under field test conditions . 29
10.5 Up-time . 29
10.6 Maintenance . 30
Annex A (normative) Evaluation of test data . 31
A.1 Introduction . 31
A.2 Bias. 31
A.3 Repeatability . 32
A.4 Effect of influence quantities . 32
A.5 Combined performance requirement . 32
A.6 Worked example . 34
A.6.1 Bias. 34
A.6.2 Repeatability . 35
A.6.3 Influence conditions . 35
A.7 Worked example — Field tests . 36
Annex B (informative) Reference methods . 40
B.1 Laboratory methods . 40
B.2 Field (in situ) methods . 40
Annex C (informative) Reference uncertainty and error calculations . 41
Annex D (informative) Example report format . 43
Bibliography . 46
3
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SIST EN 17694-2:2023
EN 17694-2:2023 (E)
European foreword
This document (EN 17694-2:2023) has been prepared by Technical Committee CEN/TC 318
“Hydrometry”, the secretariat of which is held by BSI.
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 2023, and conflicting national standards shall
be withdrawn at the latest by November 2023.
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 standard is published in two parts:
— EN 17694-1, Hydrometry — Minimum performance requirements and test procedures for water
monitoring equipment — Devices for the determination of flow — Part 1: Open channel
instrumentation
— EN 17694-2, Hydrometry — Minimum performance requirements and test procedures for water
monitoring equipment — Devices for the determination of flow — Part 2: Closed conduit
instrumentation
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, Türkiye and the United
Kingdom.
4
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SIST EN 17694-2:2023
EN 17694-2:2023 (E)
Introduction
This document is a product standard for instrumentation for the determination of the flow of waters in
closed conduits (e.g. effluent discharges from industrial installations, and wastewaters from sewage
treatment works, water irrigation channels and water transfer channels). A closed conduit instrument
(CCI) is a device that is normally fixed in position and used mainly to measure either volumetric flow-rate
and/or total volume passed. Certain CCI, e.g. Coriolis devices measure mass flow-rate and/or total mass
passed, from which volumetric flow may be derived, using the density of the water. This document
defines general requirements, minimum performance requirements, and test procedures. A CCI that is
shown, by means of the tests, to conform with the general requirements and performance requirements
is considered to be fit for purpose. However, this document does not cover the installation and on-going
use of a CCI, and also excludes instrumentation that is subject to separate legal control, for example, the
Measuring Instruments Directive.
The acronym “CCI” is used throughout this document except where it is necessary to be specific about the
particular type or component (e.g. sensor) of a device.
The general requirements and performance requirements specified in this document are intended to be
independent of measurement technology and applicable to all CCIs. The general requirements include
several features that are necessary to meet users’ applications and information that should be included
in associated documents.
The performance tests comprise testing carried out under laboratory and field conditions. They are
designed to determine, in a systematic and consistent way, the capability of CCI to make reliable
measurements. The testing focuses on key performance characteristics. Statistical procedures are defined
for evaluation of the test data.
Measurement ranges are not specified as part of the performance requirements though a minimum ratio
(maximum measured value: minimum measured value) is specified. It is for the manufacturer of the CCI
to decide on the measurement range over which the performance requirements are shown to be met by
the specified test procedures. Similarly, it is for the CCI manufacturer to decide on the intended uses
(applications) which will inform the design of the field trial.
Water monitoring equipment is widely used for compliance monitoring purposes under national and
European regulations.
5
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SIST EN 17694-2:2023
EN 17694-2:2023 (E)
1 Scope
This document specifies general requirements, minimum performance requirements and test procedures
for instrumentation used to measure either volumetric flow-rate and/or total volume passed of water in
closed conduits. It covers all closed conduit instrument (CCI) technologies intended to operate in closed
pressurized pipes and partially filled pipes. Requirements are expressed in volumetric units which may
be converted to mass using the density of the water.
It is recognized that for some CCIs certain tests cannot be carried out.
The data obtained from the testing of CCIs in accordance with the requirements of the Measuring
Instruments Directive [1] or EN ISO 4064-1 [2] can be used to meet, in part, the requirements specified
in this document. However, for the avoidance of doubt, compliance with the requirements of this
document does not equate to compliance with the requirements of the Measuring Instruments Directive
or EN ISO 4064-1.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology 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
3.1
combined performance requirement
combination of individual performance requirements
3.2
conduit
pipe through which water is flowing
3.3
closed conduit instrument
CCI
device(s) which measures the flow-rate or totalized volume of water passing along a conduit or computes
such quantities from measurements of one or more properties which have a defined relationship with
the flow-rate
Note 1 to entry: A closed conduit instrument can, for example, include a complete flow-metering system, such as: a
flow sensor and transmitter, a mechanical CCI including any ancillary device required to derive an electronic output,
a velocity-area CCI comprising a water velocity sensor with a water level sensor and associated electronics, or a
non-standardized primary device with a differential pressure sensor and associated electronics.
3.4
determinand
property that is required to be measured
6
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SIST EN 17694-2:2023
EN 17694-2:2023 (E)
3.5
expanded uncertainty
expanded measurement uncertainty
U
product of a combined measurement uncertainty and a factor larger than the number one
Note 1 to entry: The factor depends upon the type of probability distribution of the output quantity in a
measurement model and on the selected coverage probability.
Note 2 to entry: The term “factor” in this definition refers to a coverage factor.
Note 3 to entry: Expanded measurement uncertainty is termed “overall uncertainty” in paragraph 5 of
Recommendation INC-1 (1980) (see the GUM) and simply “uncertainty” in IEC documents.
[ISO/IEC Guide 99:2007, 2.35 plus notes] [3]
3.6
flow-rate
q
volume of water passing through the CCI per unit time
3.7
influence quantity
quantity, generally external to the CCI, which may affect the performance of the equipment
3.8
insertion sensor
sensor designed to be inserted into a pipe through a tapping or other fitting, or mounted internally within
a pipe, in direct contact with the water and connected to a transmitter mounted externally to the pipe
3.9
measurement range
range over which the CCI conforms within the performance requirements specified in this document
Note to 1 entry: The measurement range is defined from a minimum non-zero value to a maximum value.
3.10
non-invasive sensor
sensor for application to a pipe which attaches to the outside of a pipe and requires no tapping, drilling
or cutting of the pipe to install, for example clamp-on ultrasonic transducers
3.11
percentage error
error in measurement expressed as a percentage of the true or actual value
Note 1 to entry: In this document, the true or actual value is the reference value and percentage error is calculated
using the following equation: percentage error = 100 × (measured value – reference value)/reference value.
3.12
performance requirement
one of the quantities (described by values, tolerances, range) that defines a CCI’s performance
7
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SIST EN 17694-2:2023
EN 17694-2:2023 (E)
3.13
rated operating conditions
minimum to maximum values of any environmental, fluid or electrical parameter within which a CCI is
designed to operate without adjustment, within the performance requirements specified in this
document
3.14
reference conditions
specified set of values (including tolerances) of influence variables, delivering representative values of
performance requirements
3.15
reference method
method to be used to obtain the determinand value to a stated uncertainty, against which the readings
from the CCI under test can be compared
3.16
repeatability
ability of a CCI to provide closely similar indications for repeated applications of the same determinand
under the same conditions of measurement
3.17
sensor
transducer consisting of one or more components from which is derived an electrical or mechanical
output related to a property from which the flow-rate may be computed
3.18
totalized volume
total volume of water which has been measured by the CCI over a period of time which commenced when
the totalizer was set to zero
4 Symbols
For the purposes of this document the following symbols apply.
b bias
S repeatability
R
X errors due to variations in supply voltage
V
X errors due to variations in output impedance
O
X errors due to variations in water temperature
FT
errors due to variations in ambient air temperature
X
T
X errors due to variations in relative humidity
RH
X errors due to variations in sensor location
SL
X errors due to variations in stray currents
SC
U combined performance requirement
C
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SIST EN 17694-2:2023
EN 17694-2:2023 (E)
5 Principle
This document sets general requirements, minimum performance requirements and test procedures for
a CCI that is to be used for determining the flow of water in closed conduits.
The general requirements are based on experience of users’ needs when operating a CCI in a range of
applications. Many are consistent with general requirements specified in EN ISO 4064-1.
The minimum performance requirements specify limit values in terms of percentage error for
measurement bias, repeatability, a range of environmental and sensor operational parameters, and for a
combination of all of these values. A CCI that can be demonstrated by the specified tests to conform with
the performance requirements is judged to be fit for purpose.
For the majority of applications where a CCI is used, the required parameter is volumetric flow-rate.
In Table 2 the combined performance requirement is less than the sum of the specified individual
performance values combined in quadrature. This allows for some differences in the performance of a
CCI with respect to the individual requirements within an overall combined performance requirement.
The laboratory performance tests are designed to show whether a CCI can conform with the applicable
performance requirements under a range of environmental and sensor operational conditions.
Laboratory testing is used to determine the performance characteristics in a systematic and consistent
way in a controlled environment. Several of the laboratory tests correspond to tests specified in
EN ISO 4064-2 [4] and ISO 12242 [5]. For CCI that are tested to demonstrate conformity with
EN ISO 4064-1 and ISO 12242 the test data can also be used for the purposes of this document thereby
minimizing the amount of testing.
Statistical procedures are defined for evaluation of the laboratory test data to produce the individual
performance characteristic measurement uncertainties, u, and the combined performance characteristic
measurement uncertainty, U . They are based on the ISO/IEC Guide 98-3 [6]. The measured errors arising
C
from the tests for each performance tests are converted to standard uncertainties, taking into account
the distribution of errors. To obtain the combined performance characteristic, the individual
uncertainties are combined using a root sum of squares, as described in the GUM, with due account taken
of the contribution of each component through the use of sensitivity coefficients. To determine sensitivity
coefficients, it is necessary to know the functions by which each component contributes to overall error.
In the case of CCI testing this will rarely be known. Hence, for the purposes of this document, the
sensitivity coefficients are all taken as 1.
The combined performance characteristic, U , is expressed as an expanded uncertainty. The expanded
C
uncertainty, (U), is obtained by multiplying the standard uncertainty by a coverage factor. The coverage
factor is determined by the confidence level. This document uses a 95 % confidence with a coverage
factor assumed to be 2.
The field trial is used to demonstrate that the performance of a CCI can be maintained under operational
conditions and to determine the CCI’s up-time.
9
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SIST EN 17694-2:2023
EN 17694-2:2023 (E)
6 General requirements
6.1 Requirements for closed conduit instrumentation
A CCI shall have:
a) a unique designation that unambiguously identifies the CCI (e.g. model, serial number);
b) a means of protection against inadvertent or unauthorized access to the control functions (e.g.
password, physical locks, etc);
c) an output signal and/or display scaled in metric units (the units of measurement shall be displayed
on the indicating device);
d) one or more output signals and/or a means of displaying the measured determinand and/or either
the totalized volume and/or volumetric flow-rate. If the CCI does not incorporate a local display, it
shall be possible for an authorized person to obtain the current reading by communicating with the
CCI on site using a portable device, such as a laptop, tablet or smart phone. Communication with a
portable device to display a reading shall not interrupt the measurement and shall not allow the user
to defeat access security features;
e) a means of displaying its operating status, for example, normal operation, stand-by, maintenance
mode or malfunction;
f) a means to return to normal operating mode from maintenance, service or programming mode if no
user interactions have been detected after a defined time period;
g) an audible or visual method of indicating loss of power supply (applies only to CCI operating from an
external power supply), e.g. a relay that fails open;
h) an audible or visual method of indicating when the power supply voltage is below its normal
operating limit (applies only to CCIs operating from a battery);
i) a means for preventing unauthorized resetting of the total recorded volume for abstraction metering
and/or effluent discharge monitoring; a symbol, incorporated into the indication device t
...
SLOVENSKI STANDARD
oSIST prEN 17694-2:2021
01-oktober-2021
Hidrometrija - Zahteve za tehnične lastnosti in preskusni postopki za opremo za
nadzor vode - Naprave za ugotavljanje pretoka - 2. del: Instrumenti za merjenje v
zaprtem vodu
Hydrometry - Performance requirements and test procedures for water monitoring
equipment - Devices for the determination of flow Part 2: Closed conduit instrumentation
Hydrometrie - Leistungsanforderungen und Prüfverfahren für
Wasserüberwachungsgeräte - Geräte zur Bestimmung des Durchflusses - Teil 2:
Messgeräte für geschlossene Rohrleitungen
Ta slovenski standard je istoveten z: prEN 17694-2
ICS:
07.060 Geologija. Meteorologija. Geology. Meteorology.
Hidrologija Hydrology
17.120.10 Pretok v zaprtih vodih Flow in closed conduits
oSIST prEN 17694-2:2021 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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oSIST prEN 17694-2:2021
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oSIST prEN 17694-2:2021
DRAFT
EUROPEAN STANDARD
prEN 17964-2
NORME EUROPÉENNE
EUROPÄISCHE NORM
September 2021
ICS 07.060; 17.120.20
English Version
Hydrometry - Performance requirements and test
procedures for water monitoring equipment - Devices for
the determination of flow Part 2: Closed conduit
instrumentation
Hydrometrie - Leistungsanforderungen und
Prüfverfahren für Wasserüberwachungsgeräte - Geräte
zur Bestimmung des Durchflusses - Teil 2: Messgeräte
für geschlossene Rohrleitungen
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 318.
If this draft becomes a European Standard, 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.
This draft European Standard was established by CEN 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.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.
Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.
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. prEN 17964-2:2021 E
worldwide for CEN national Members.
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oSIST prEN 17694-2:2021
prEN 17694-2:2021 (E)
Contents Page
European foreword . 4
Introduction . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Symbols . 8
5 Principle . 8
6 General requirements . 9
6.1 Requirements for closed conduit instrumentation . 9
6.2 Requirements for associated documentation . 10
7 Performance requirements . 11
7.1 Expression of performance requirements . 11
7.2 Performance requirements . 12
7.3 Data retention . 13
7.4 Environmental requirements . 14
7.5 Water temperature requirements . 14
7.6 Installation influences . 14
7.7 Field test requirements. 14
8 Testing . 15
8.1 General requirements for testing . 15
8.2 Laboratory test conditions . 15
8.3 Reporting . 17
9 Laboratory test procedures . 17
9.1 Guidance for establishing a test plan . 17
9.2 Verification by inspection . 20
9.3 Performance tests . 20
9.3.1 Loss of power for electronic CCIs. 20
9.3.2 Bias and repeatability. 20
9.3.3 Supply voltage . 21
9.3.4 Output impedance. 22
9.3.5 Water temperature . 22
9.3.6 Ambient air temperature and relative humidity . 22
9.3.7 Sensor location . 23
9.3.8 Presence of stray currents . 24
9.3.9 Bi-directional flow . 25
9.3.10 Flow reversal . 25
9.3.11 Ancillary devices . 25
9.3.12 Effect of conduit material . 25
9.3.13 Effect of conduit size . 26
9.3.14 Fill level . 27
9.3.15 Response time . 27
10 Field test procedures . 28
10.1 Objective of field test . 28
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10.2 Field test plan . 28
10.3 Field test requirements. 28
10.4 Error under field test conditions . 29
10.5 Up-time . 29
10.6 Maintenance . 30
Annex A (normative) Evaluation of test data . 31
Annex B (Informative) Reference methods . 40
Annex C (Informative) Reference uncertainty and error calculations . 41
Annex D (informative) Example report format . 43
Bibliography . 46
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European foreword
This document (prEN 17694-2) has been prepared by Technical Committee CEN/TC 318
“Hydrometry”, the secretariat of which is held by BSI.
This document is currently submitted to the CEN Enquiry.
This standard is published in two parts:
prEN 17694-1 Hydrometry - Performance requirements and test procedures for water monitoring
equipment – Devices for the determination of flow - Part 1 Open channel instrumentation
prEN 17694-2 Hydrometry - Performance requirements and test procedures for water monitoring
equipment – Devices for the determination of flow - Part 2 Closed conduit instrumentation
This document has been prepared under a Standardization Request given to CEN by the
European Commission and the European Free Trade Association.
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Introduction
This document is a product standard for instrumentation for the determination of the flow of
waters in closed conduits (e.g. effluent discharges from industrial installations, and wastewaters
from sewage treatment works, water irrigation channels and water transfer channels). A closed
conduit instrument (CCI) is a device that is normally fixed in position and used mainly to
measure either volumetric flow-rate and/or total volume passed. Certain CCI, e.g. Coriolis
devices measure mass flow-rate and/or total mass passed, from which volumetric flow may be
derived, using the density of the fluid. This document defines general requirements, minimum
performance requirements, and test procedures. A CCI that is shown, by means of the tests, to
conform with the general requirements and performance requirements is considered to be fit
for purpose. However, this document does not cover the installation and on-going use of a CCI,
and also excludes instrumentation that is subject to separate legal control, for example, the
Measuring Instruments Directive.
The acronym “CCI” is used throughout this document except where it is necessary to be specific
about the particular type or component (e.g. sensor) of a device.
The general requirements and performance requirements specified in this document are
intended to be independent of measurement technology and applicable to all CCIs. The general
requirements include several features that are necessary to meet users’ applications and
information that should be included in associated documents.
The performance tests comprise testing carried out under laboratory and field conditions. They
are designed to determine, in a systematic and consistent way, the capability of CCI to make
reliable measurements. The testing focuses on key performance characteristics. Statistical
procedures are defined for evaluation of the test data.
Measurement ranges are not specified as part of the performance requirements though a
minimum ratio (maximum measured value: minimum measured value) is specified. It is for the
manufacturer of the CCI to decide on the measurement range over which the performance
requirements are shown to be met by the specified test procedures. Similarly, it is for the CCI
manufacturer to decide on the intended uses (applications) which will inform the design of the
field trial.
Water monitoring equipment is widely used for compliance monitoring purposes under
national and European regulations.
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1 Scope
This document specifies general requirements, minimum performance requirements and test
procedures for instrumentation used to measure either volumetric flow-rate and/or total
volume passed of water in closed conduits. It covers all closed conduit instrument (CCI)
technologies intended to operate in closed pressurized pipes and partially filled pipes.
Requirements are expressed in volumetric units which may be converted to mass using the fluid
density.
It is recognized that for some CCIs certain tests cannot be carried out.
The data obtained from the testing of CCIs in accordance with the requirements of the Measuring
Instruments Directive [1] or EN ISO 4064-1 [2] can be used to meet, in part, the requirements
specified in this document. However, for the avoidance of doubt, compliance with the
requirements of this document does not equate to compliance with the requirements of the
Measuring Instruments Directive or EN ISO 4064-1.
2 Normative references
There are no normative references in this document.
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
3.1
combined performance requirement
combination of individual performance requirements
3.2
conduit
pipe through which water is flowing
3.3
closed conduit instrument
CCI
device(s) which measures the flow-rate or totalized volume of water passing along a conduit or
computes such quantities from measurements of one or more properties which have a defined
relationship with the flow-rate
Note to 1 entry: A closed conduit instrument can, for example, include a complete flow-metering system,
such as: a flow sensor and transmitter, a mechanical CCI including any ancillary device required to derive
an electronic output, a velocity-area CCI comprising a water velocity sensor with a water level sensor,
associated electronics and flow computer, a bespoke gauge with a water level sensor, associated
electronics and flow computer, a non-standardized primary device with a differential pressure sensor,
associated electronics and flow computer.
3.4
determinand
the property that is required to be measured
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3.5
expanded uncertainty
U
expanded measurement uncertainty product of a combined measurement uncertainty and a
factor larger than the number one
Note 1 to entry: The factor depends upon the type of probability distribution of the output quantity in a
measurement model and on the selected coverage probability.
Note 2 to entry: The term “factor” in this definition refers to a coverage factor.
Note 3 to entry: Expanded measurement uncertainty is termed “overall uncertainty” in paragraph 5 of
Recommendation INC-1 (1980) (see the GUM) and simply “uncertainty” in IEC documents.
[ISO/IEC Guide 99:2007, 2.35 plus notes]
3.6
flow-rate
q
volume of water passing through the CCI per unit time
3.7
influence quantity
any quantity, generally external to the CCI, which may affect the performance of the equipment
3.8
measurement range
range over which the CCI conforms within the performance requirements specified in this
document
Note to 1 entry: The measurement range is defined from a minimum non-zero value to a maximum value.
3.9
non-invasive sensor
sensor for application to a pipe which attaches to the outside of a pipe and requires no tapping,
drilling or cutting of the pipe to install, for example clamp-on ultrasonic transducers
3.10
percentage error
error in measurement expressed as a percentage of the true or actual value
Note to 1 entry: In this document, the true or actual value is the reference value and percentage error is
calculated using the following equation: percentage error = 100 X (measured value – reference
value)/reference value.
3.11
performance requirement
one of the quantities (described by values, tolerances, range) that defines a CCI’s performance
3.12
rated operating conditions
minimum to maximum values of any environmental, fluid or electrical parameter within which
a CCI is designed to operate without adjustment, within the performance requirements specified
in this document
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3.13
reference conditions
specified set of values (including tolerances) of influence variables, delivering representative
values of performance requirements
3.14
reference method
method to be used to obtain the determinand value to a stated uncertainty, against which the
readings from the CCI under test can be compared
3.15
repeatability
ability of a CCI to provide closely similar indications for repeated applications of the same
determinand under the same conditions of measurement
3.16
sensor
transducer consisting of one or more components from which is derived an electrical or
mechanical output related to a property from which the flow-rate may be computed
3.17
totalized volume
the total volume of water which has been measured by the CCI over a period of time which
commenced when the totalizer was set to zero
4 Symbols
For the purposes of this standard the following symbols apply.
b Bias
S Repeatability
r
X Errors due to variations in supply voltage
V
Errors due to variations in output impedance
X
O
Errors due to variations in fluid temperature
X
FT
X Errors due to variations in ambient air temperature
T
X Errors due to variations in relative humidity
RH
X Errors due to variations in sensor location
SL
Errors due to variations in stray currents
X
SC
U
Combined performance requirement
C
5 Principle
This document sets general requirements, minimum performance requirements and test
procedures for a CCI that is to be used for determining the flow of water in closed conduits.
The general requirements are based on experience of users’ needs when operating a CCI in a
range of applications. Many are consistent with general requirements specified in
EN ISO 4064-1.
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The minimum performance requirements specify limit values in terms of percentage error for
measurement bias, repeatability, a range of environmental and sensor operational parameters,
and for a combination of all of these values. A CCI that can be demonstrated by the specified tests
to conform with the performance requirements is judged to be fit for purpose.
For the majority of applications where CCI are used, the required parameter is volumetric flow-
rate.
In Table 2 the combined performance requirement is less than the sum of the specified
individual performance values combined in quadrature. This allows for some differences in
performance of CCIs with respect to the individual requirements within an overall combined
performance requirement.
The laboratory performance tests are designed to show whether a CCI can conform with the
applicable performance requirements under a range of environmental and sensor operational
conditions. Laboratory testing is used to determine the performance characteristics in a
systematic and consistent way in a controlled environment. Several of the laboratory tests
correspond to tests specified in EN ISO 4064-2 [3] and ISO 12242 [4]. For CCI that are tested to
demonstrate conformity with EN ISO 4064 and ISO 12242 the test data can also be used for the
purposes of this document thereby minimizing the amount of testing.
Statistical procedures are defined for evaluation of the laboratory test data to produce the
individual performance characteristic measurement uncertainties, u, and the combined
performance characteristic measurement uncertainty, U . They are based on the
C
ISO/IEC Guide 98-3 [5]. The measured errors arising from the tests for each performance tests
are converted to standard uncertainties, taking into account the probable distribution of errors.
To obtain the combined performance characteristic, the individual uncertainties are combined
using a root sum of squares, as described in the GUM, with due account taken of the contribution
of each component through the use of sensitivity coefficients. To determine sensitivity
coefficients, it is necessary to know the functions by which each component contributes to
overall error. In the case of CCI testing this will rarely be known. Hence for the purposes of this
standard, the sensitivity coefficients are all taken as 1.
The combined performance characteristic, U , is expressed as an expanded uncertainty. The
C
expanded uncertainty, (U), is obtained by multiplying the standard uncertainty by a coverage
factor. The coverage factor is determined by the confidence level. This document uses a 95 %
confidence with a coverage factor assumed to be 2.
The field trial is used to demonstrate that the performance of a CCI can be maintained under
operational conditions and to determine the CCI’s up-time.
6 General requirements
6.1 Requirements for closed conduit instrumentation
A CCI shall have:
a) an unique designation that unambiguously identifies the CCI (e.g. model, serial number);
b) a means of protection against inadvertent or unauthorized access to the control functions
(e.g. password, physical locks, etc);
c) an output signal and/or display scaled in metric units (the units of measurement shall be
displayed on the indicating device);
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d) one or more output signals and/or a means of displaying the measured determinand and/or
either the totalized volume and / or volumetric flow-rate. If the CCI does not incorporate a
local display, it shall be possible for an authorized person to obtain the current reading by
communicating with the CCI on site using a portable device, such as a laptop, tablet or smart
phone. Communication with a portable device to display a reading shall not interrupt the
measurement.
e) a means of displaying its operating status, for example, normal operation, stand-by,
maintenance mode or malfunction;
f) an audible or visual method of indicating loss of power supply (applies only to CCI operating
from an external power supply), e.g. a relay that fails open;
g) an audible or visual method of indicating when the power supply voltage is below its normal
operating limit (applies only to CCIs operating from a battery);
h) a means for preventing unauthorized resetting of the total recorded volume for abstraction
metering and / or effluent discharge monitoring; a symbol, incorporated into the indication
device to show the flow direction, for bi-directional CCI;
NOTE A pointer rotating clockwise with increasing flow and counter-clockwise with reverse
flow is acceptable but reliance on an increasing or decreasing total is not.
i) a clear marking of the direction of forward flow (in the case of a bi-directional CCI this
should be the direction of flow which gives an increase in the total flow recorded. For a CCI
which has been wet calibrated, this should be the direction of flow in which the CCI has been
calibrated);
j) a means to subtract from the indicated volume or to record separately the reverse flow
volume, for a bi-directional CCI;
k) an upstream strainer or filter to protect the CCI, where recommended by the manufacturer;
-1 -
l) a minimum rated operating range for fluid conductivity between 50 μS cm to 1200 μS cm
1
for an electro-magnetic device.
6.2 Requirements for associated documentation
The following information shall be incorporated into the associated documentation:
a) operating instructions which cover the full functionality and measurement principle of the
CCI;
b) generic guidance on the time period over which the CCI can operate continuously without
requiring manual adjustment or intervention;
NOTE 1 Automatic routines for cleaning, maintenance or recalibration can be used to maintain
performance within the required limits between manual interventions. It is up to the user to ensure
that a suitable regime is adopted for an individual application.
c) a statement of the types of primary device, where applicable, for which the CCI can compute
flow-rate without the input of data other than the type and dimensions of the structure and
a zero datum;
d) a statement of whether the CCI is designed to measure flow in both forward and
reverse directions;
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e) a statement defining minimum up and downstream straight lengths of conduit of uniform
section adjacent to the sensor required to meet the performance requirements of this
document;
f) a statement of any limitations on the material of conduit into or onto which the CCI’s sensor
can be installed;
g) a statement of any limitations on the conduit dimensions or shape (including wall thickness
or pipe schedule if appropriate), into or onto which the CCI’s sensor can be installed. If
multiple sensors are required, for example in a large conduit, the number and spacing of
those sensors shall be stated;
h) for non-contact velocity sensors, a statement of the minimum and maximum separation
distances from the sensor face to the fluid surface;
i) a statement of the minimum measurable fluid depth under free surface conditions (the
maximum measurable fluid depth is assumed to be full bore), for CCIs intended to operate
in partially filled pipes. The manufacturer shall also state whether the CCI can maintain
performance within the requirements of this document under surcharged conditions. A CCI
that can only operate in partially filled pipe with free surface conditions should be tested in
accordance with EN 17694-1 [6];
j) a statement, where appropriate, of the rated operating conditions for water pressure;
k) a statement of the quality (e.g. contaminants, salinity) nature and quantity of particulate or
other material that the CCI can pass whilst maintaining its performance within the limits of
this standard. If a minimum level of particulate is required for operation of the CCI, this too
shall be stated;
l) a statement of any specific requirements relating to the location or shielding of components
necessary to maintain performance within the limits of this standard under varying
environmental conditions
m) a statement, for electronic CCI, of the rated operating conditions for the power supply;
n) a statement, for electronic CCI, of the rated operating conditions for the signal load
impedance on the analogue output, if present;
o) a statement of the rated operating conditions for water temperature, ambient temperature
and humidity as appropriate;
NOTE 2 The influence of ambient temperature and relative humidity on the performance of a CCI
is tested (see 7.4 and 9.3.6) over the rated environmental operating conditions.
p) the minimum rated operating range for fluid conductivity for an electromagnetic CCI.
7 Performance requirements
7.1 Expression of performance requirements
Specific requirements are expressed as bias (b), variations in error (X), standard deviation (u)
or expanded uncertainty (U) as shown in Table 1. Not all requirements will apply to every CCI
Annex A describes in detail how the values are calculated for each requirement.
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