EN ISO 16911-2:2013

SLOVENSKI STANDARD
01-julij-2014
(PLVLMHQHSUHPLþQLKYLURY5RþQRLQDYWRPDWVNRGRORþHYDQMHKLWURVWLLQ
YROXPHQVNHJDSUHWRNDYRGYRGQLNLKGHO$YWRPDWVNLPHULOQLVLVWHPL,62

Stationary source emissions - Manual and automatic determination of velocity and
volume flow rate in ducts - Part 2: Automated measuring systems (ISO 16911-2:2013)
Emissionen aus stationären Quellen - Manuelle und automatische Bestimmung der
Geschwindigkeit und des Volumenstroms in Abgaskanälen - Teil 2: Kontinuierliche
Messverfahren (ISO 16911-2:2013)
Émissions de sources fixes - Détermination manuelle et automatique de la vitesse et du
débit-volume d'écoulement dans les conduits - Partie 2: Systèmes de mesure
automatiques (ISO 16911-2:2013)
Ta slovenski standard je istoveten z: EN ISO 16911-2:2013
ICS:
13.040.40 (PLVLMHQHSUHPLþQLKYLURY Stationary source emissions
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN ISO 16911-2
NORME EUROPÉENNE
EUROPÄISCHE NORM
March 2013
ICS 13.040.40
English Version
Stationary source emissions - Manual and automatic
determination of velocity and volume flow rate in ducts - Part 2:
Automated measuring systems (ISO 16911-2:2013)
Émissions de sources fixes - Détermination manuelle et Emissionen aus stationären Quellen - Manuelle und
automatique de la vitesse et du débit-volume d'écoulement automatische Bestimmung der Geschwindigkeit und des
dans les conduits - Partie 2: Systèmes de mesure Volumenstroms in Abgaskanälen - Teil 2: Kontinuierliche
automatiques (ISO 16911-2:2013) Messverfahren (ISO 16911-2:2013)
This European Standard was approved by CEN on 23 February 2013.

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.

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Kingdom.
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COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2013 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 16911-2:2013: E
worldwide for CEN national Members.

Contents Page
Foreword . 3

Foreword
This document (EN ISO 16911-2:2013) has been prepared by Technical Committee CEN/TC 264 “Air quality",
the secretariat of which is held by DIN, in collaboration with Technical Committee ISO/TC 146 "Air quality".
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 September 2013, and conflicting national standards shall be
withdrawn at the latest by September 2013.
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.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech
Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece,
Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.

INTERNATIONAL ISO
STANDARD 16911-2
First edition
2013-03-01
Stationary source emissions — Manual
and automatic determination of velocity
and volume flow rate in ducts —
Part 2:
Automated measuring systems
Émissions de sources fixes — Détermination manuelle et automatique
de la vitesse et du débit-volume d’écoulement dans les conduits —
Partie 2: Systèmes de mesure automatiques
Reference number
ISO 16911-2:2013(E)
©
ISO 2013
ISO 16911-2:2013(E)
© ISO 2013
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested 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 copyright@iso.org
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Published in Switzerland
ii © ISO 2013 – All rights reserved

ISO 16911-2:2013(E)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviations . 4
4.1 Symbols . 4
4.2 Abbreviations . 5
5 Principle . 6
5.1 General . 6
5.2 Importance of minimizing systematic errors . 6
5.3 Relationship to EN 14181 . 7
6 Type testing, quality assurance level 1 data . 7
6.1 Introduction . 7
6.2 Performance criteria . 8
6.3 Flow reference material or procedure. 8
6.4 Quality assurance level 1 calculation . 9
6.5 Velocity check points and quality assurance level 3 . 9
7 Selection of automated measuring system location .10
7.1 General .10
7.2 Selection based upon pre-investigation .10
7.3 Selection based upon a predictable flow profile .10
7.4 Qualifying the automated measuring system calibration through a type 2 quality
assurance level 2 procedure .11
7.5 Ports and working platforms .11
8 Pre-investigation of flow profile .11
8.1 General .11
8.2 Pre-investigation by measurement .12
8.3 Pre-investigation by computational fluid dynamics (CFD).13
8.4 Automated measuring system selection guide .14
8.5 Quality assurance level 2 requirements .14
9 Calibration and validation of the automated measuring system (quality assurance level 2
and annual surveillance test) .14
9.1 Selection of calibration method .14
9.2 Selection of calibration method, if calculation methods are used .15
9.3 Calibration procedure .15
9.4 Functional tests .15
9.5 Parallel measurements with a standard reference method .15
9.6 Wall effects .16
9.7 Automated measuring system flow calibration procedure with transit time tracer .17
9.8 Data evaluation .17
9.9 Calibration function of the automated measuring system and its validity .17
9.10 Calculation of variability .18
9.11 Test of variability and annual surveillance test of validity of the calibration function .18
2 18
9.12 Test of R .
9.13 Quality assurance level 2 and annual surveillance test report .18
10 Commissioning documentation .19
11 On-going quality assurance during operation (quality assurance level 3) .19
12 Assessment of uncertainty in volume flow rate .19
ISO 16911-2:2013(E)
Annex A (informative) Example of calculation of the calibration function (data from tests in
Copenhagen and Wilhelmshaven) .20
Annex B (informative) Flow profile characteristics .32
Annex C (informative) Determination of measuring points and/or paths .37
Annex D (normative) Treatment of a polynomial calibration function .41
Annex E (normative) Values of k (N) and t .42
v 0,95(N − 1)
Annex F (informative) Example of a pre-investigation measurement .43
Annex G (informative) Computational fluid dynamics issues .50
Annex H (informative) The use of time of flight measurement instruments based on modulated
laser light .54
Annex I (informative) Relationship between this International Standard and the essential
requirements of EU Directives .55
Bibliography .56
iv © ISO 2013 – All rights reserved

ISO 16911-2:2013(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 16911-2 was prepared by the European Committee for Standardization (CEN) in collaboration with
ISO Technical Committee TC 146, Air quality, Subcommittee SC 1, Stationary source emissions.
ISO 16911 consists of the following parts, under the general title Stationary source emissions — Manual
and automatic determination of velocity and volume flow rate in ducts:
— Part 1: Manual reference method
— Part 2: Automated measuring systems
ISO 16911-2:2013(E)
Introduction
EN ISO 16911-2 describes the quality assurance (QA) procedures related to automated measuring
systems (AMSs) for the determination of the volume flow rate of flue gas with a total uncertainty that
[4]
accords with the requirements of Commission Decision of 2007-07-18.
The calibration and validation of flow AMSs are performed by parallel measurements with the reference
manual method described in EN ISO 16911-1.
The purpose of EN ISO 16911-2 is to secure flow monitoring with a minimized uncertainty for use
[1] [2] [5]
according to EU Directive 2000/76/EC, EU Directive 2001/80/EC, and EU Directive 2010/75/EU.
The purpose of EN ISO 16911-2 is also to secure flow monitoring with an overall uncertainty equal
[4]
to or less than stipulated in Commission Decision of 2007-07-18 and establishing guidelines for the
[3]
monitoring and reporting of greenhouse gas emissions pursuant to Directive 2003/87/EC.
vi © ISO 2013 – All rights reserved

INTERNATIONAL STANDARD ISO 16911-2:2013(E)
Stationary source emissions — Manual and automatic
determination of velocity and volume flow rate in ducts —
Part 2:
Automated measuring systems
1 Scope
EN ISO 16911-2 describes specific requirements for automated measuring system (AMS) flow monitoring.
It is partly derived from EN 14181 which is the general document on the quality assurance of AMSs and
is applicable in conjunction with that document.
EN ISO 16911-2 specifies conditions and criteria for the choice, mounting, commissioning and
calibration of AMSs used for determining the volume flow rate from a source in ducted gaseous
streams. EN ISO 16911-2 is applicable by correlation with the manual reference methods described in
EN ISO 16911-1.
EN ISO 16911-2 is primarily developed for monitoring emissions from waste incinerators and large
combustion plants. From a technical point of view, it can be applied to other processes for which flow
rate measurement is required with a defined and minimized uncertainty.
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 14956, Air quality — Evaluation of the suitability of a measurement procedure by comparison with a
required measurement uncertainty
EN ISO 16911-1:2013, Stationary source emissions — Manual and automatic determination of velocity and
volume flow rate in ducts — Part 1 Manual reference method
EN 14181:2004, Stationary source emissions — Quality assurance of automated measuring systems
EN 15267-3:2007, Air quality — Certification of automated measuring systems — Part 3: Performance criteria
and test procedures for automated measuring systems for monitoring emissions from stationary sources
EN 15259, Air quality — Measurement of stationary source emissions — Requirements for measurement
sections and sites and for the measurement objective, plan and report
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 14181 and the following apply.
3.1
automated measuring system
AMS
measuring system permanently installed on site for continuous monitoring of flow
Note 1 to entry: An AMS is a monitoring technology which is traceable to a reference method.
ISO 16911-2:2013(E)
Note 2 to entry: The AMS is a complete system for measuring flow rate, and includes the features required for
conducting regular functional checks.
3.2
cross-sensitivity
response of the AMS to determinants other than flow rate, e.g. caused by the presence of particulate
matter, changes in gas composition, duct temperature
3.3
linearity
lack of fit
systematic deviation, within the range of application, between the accepted value of a flow reference
material applied to the measuring system and the corresponding measurement result produced by the AMS
Note 1 to entry: The linearity test is described in EN 15267-3:2007, Annex B.
3.4
limit of detection
minimum value of the measurand for which the measuring system is not in the basic state, with a
stated probability
Note 1 to entry: Basic state is normally the zero reading or the minimum measured by the instrument.
3.5
period of unattended operation
maintenance interval
maximum interval of time for which the performance characteristics remain within a predefined range
without external servicing, e.g. calibration or adjustment
3.6
reproducibility under field conditions
measure of the agreement between two measurements in field tests at a level of confidence of 95 %
expressed as the standard deviation of the difference of paired measurements:
n
xx−
()
∑ 12ii
(1)
i=1
s =
D
2n
where
x is the ith measurement result of AMS 1;
1i
x is the ith measurement result of AMS 2;
2i
n is the number of parallel measurements.
Note 1 to entry: The absolute reproducibility in the field, R , is calculated according to:
f,abs
R = t × s (2)
f,abs 0,05(N − 1) D
where
t is the two-sided Student t-factor at a confidence level of 0,05, with N − 1 degrees of freedom.
0,05(N − 1)
Note 2 to entry: Adapted from EN 15267-3:2007.
2 © ISO 2013 – All rights reserved

ISO 16911-2:2013(E)
3.7
standard reference method
SRM
method described and standardized to define an air quality characteristic, temporarily installed on site
for verification purposes
Note 1 to entry: For the purposes of EN ISO 16911-2, the manual reference methods are described in EN ISO 16911-1.
3.8
flow reference material
surrogate for flow for testing the AMS performance
Note 1 to entry: A surrogate for flow is normally the parameter measured directly by the instrument, e.g. pressure,
time delay, temperature, heat dissipation or frequency.
3.9
lower reference point
output of the instrument in response to an internally generated function, intended to represent a defined
amount of the measured flow at or close to the lowest flow rate that the system can measure with a
given uncertainty
3.10
upper reference point
output of the instrument in response to an internally generated function, intended to represent a defined
amount of the measured flow at or close to the highest flow rate the system is intended to measure in a
given installation
3.11
flow profile
represented by two diagrams showing the gas velocity in the axial direction along a line across the duct
passing through the centre of gravity of the duct, and a line perpendicular to the first
Note 1 to entry: The gas velocity is expressed in m/s.
3.12
crest factor
peak-to-average ratio
characteristic of a flow profile, calculated from the measured peak value of each flow profile divided by
the average value of each flow profile in the primary and secondary monitoring paths
Note 1 to entry: If the measurement is made according to EN ISO 16911-1 and EN 15259, each measurement
represents the same area of flow in the duct, and the crest factor divisor can be calculated from a simple average
of the individual measurements.
Note 2 to entry: Crest factor shall be calculated for both flow profiles, the primary and secondary monitoring
paths, which are perpendicular to each other.
3.13
skewness
measure of asymmetry defined as the total flow to the left of the centre of the duct divided by the total
flow to the right of the centre of the duct, or the inverse thereof, whichever is larger than 1,00
Note 1 to entry: If the measurement is made according to EN ISO 16911-1 and EN 15259, each measurement
represents the same area of flow in the duct, and the skewness can be calculated from a simple average of the
individual measurements, not including a possible measurement in the centre of the duct.
Note 2 to entry: Skewness shall be calculated for both flow profiles, perpendicular to each other.
3.14
swirl
also referred to as cyclonic flow, is the tangential component of the gas velocity vector
ISO 16911-2:2013(E)
3.15
certification range
range over which the flow monitor has been tested
Note 1 to entry: The certification range is normally from zero, if the instrument reads zero, or from the lower
reference point, if the instrument does not read zero.
Note 2 to entry: The flow monitor is tested according to EN 15267-3 and EN ISO 16911-2.
3.16
primary monitoring path
P
line across the duct through the centre and where the maximum velocity is expected to be found
3.17
secondary monitoring path
S
line across the duct through the centre perpendicular to the primary monitoring path
3.18
Reynolds number
Re
d
Re=ρv
m
(3)
η
dyn
where
ρ is the gas density, in kg/m ;
v is the gas velocity, in m/s;
m
d is the duct diameter, in m;
η is the dynamic viscosity, in Pa s
dyn
4 Symbols and abbreviations
4.1 Symbols
a intercept of the calibration function
b slope of the calibration function
D
i ˆ
difference between measured SRM value y and calibrated AMS value y
i
i
D average of D
AVG i
D amount by which the AMS has to be adjusted when drift is detected
d duct diameter
k , k (N) test value for variability (based on a χ -test, with a β-value of 50 %, for N numbers of
v v
paired measurements)
n number of paired samples in parallel measurements
q volume flow rate
V
4 © ISO 2013 – All rights reserved

ISO 16911-2:2013(E)
R coefficient of determination from a linear regression
Re Reynolds number
R absolute reproducibility in the field
f.abs
s standard deviation of the differences D in parallel measurements
D i
t two-sided Student t-factor at a confidence level of 95 % with N − 1 degrees of freedom
0,95(N − 1)
t two-sided Student t-factor at a confidence level of 5 %, with N − 1 degrees of freedom
0,05(N − 1)
v weighted average of velocity across a monitoring path
AVG
v weighted average of velocity to the left of the centreline
L, AVG
v velocity measured at a point 12 % of the diameter from the duct wall to the left of the cen-
L, 12 %
treline, L
12 %
v peak velocity value on the monitoring path
PEAK
v gas velocity, in m/s
m
v weighted average of velocity to the right of the centreline
R, AVG
v velocity measured at a point 12 % of the diameter from the duct wall to the right of the
R, 12 %
centreline, R
12 %
x measured signal obtained with the AMS at AMS measuring conditions
x ith measured signal obtained with the AMS at AMS measuring conditions
i
x average of AMS measured signals x
AVG i
x ith measurement result of AMS 1
1i
x ith measurement result of AMS 2
2i
y result obtained with the SRM
y average of the SRM results y
AVG i
y best estimate for the “true value”, calculated from the AMS measured signal x by means of
cal
the calibration function
η dynamic viscosity, in Pa s
dyn
ρ gas density, in kg/m
σ uncertainty derived from requirements of legislation
4.2 Abbreviations
AMS automated measuring system
AST annual surveillance test according to EN 14181
CFD computational fluid dynamics
ELV emission limit value
ISO 16911-2:2013(E)
SRM standard reference method
QA quality assurance
QAL1 quality assurance level 1 according to EN 14181
QAL2 quality assurance level 2 according to EN 14181
QAL3 quality assurance level 3 according to EN 14181
5 Principle
5.1 General
[1]–[3][5]
To achieve the uncertainty required by the relevant EU Directives and the EU Commission
[4]
Decision, the focus of EN ISO 16911-2 is the systematic error.
EN ISO 16911-2 allows three different ways of achieving high accuracy:
— assuring correct installation by means of a pre-investigation, see 7.2;
— establishing that a fully developed flow profile is present, see 7.3;
— assuring correct measurement by a quality assurance level 2 (QAL2), see 7.4.
Noting that, if a pre-investigation has been performed, the subsequent QAL2 and annual surveillance
test (AST) may be reduced in scope, see 9.1 b).
EN ISO 16911-2 also introduces some extra requirements to type testing according to EN 15267-3,
see Clause 6.
5.2 Importance of minimizing systematic errors
[4]
The uncertainties required in Commission Decision of 2007-07-18, 2.1.3, are dependent on the “tier”
of the plant and shall be:
— 10 % for tier 1;
— 7,5 % for tier 2;
— 5 % for tier 3;
— 2,5 % for tier 4.
These uncertainties include the uncertainty for both concentration monitoring and volume flow rate
monitoring, and are uncertainties for the yearly mass emission.
The uncertainty of any measurement is combined from the uncertainties originating from random
errors and systematic errors.
Since the random error component can be reduced by repeated measurements, and the factor it is
reduced by, according to the general theory of propagation of errors, is the square root of the numbers
of measurements, the random error component of the yearly average is negligible. For example, the
yearly average is combined of (ideally) up to 17 520 half-hourly averages, in which case the uncertainty
originating from the random error component carried from the individual half-hourly average is reduced
by a factor of around 132.
However, the systematic error is not reduced by repeated measurements.
6 © ISO 2013 – All rights reserved

ISO 16911-2:2013(E)
In flow monitoring, systematic errors originate from a series of sources, e.g. changing flow profiles
under plant operating conditions not covered by the calibration function or changes in the monitoring
system, caused by contamination, blocking of holes, drift in electronics, and general wear and tear.
EN ISO 16911-2 therefore focuses on reducing the systematic error of each individual measurement.
Specifically, a pre-investigation test is recommended in order to assess whether the flow profile
changes under different plant operating conditions and this test is used for the selection and
configuration of the AMS.
5.3 Relationship to EN 14181
EN ISO 16911-2 is applicable in conjunction with the general document, EN 14181, on quality assurance
(QA) of AMSs and provides indications which are specific to flow measurements.
EN ISO 16911-2 follows, as far as possible, the structure of EN 14181, with the caveat that the emission
limit value (ELV) and the uncertainty limit specified as a 95 % confidence interval for flow monitoring
are not stated in any EU Directive. Since these data are required by the procedure prescribed in EN 14181,
suggestions for surrogate values are given in EN ISO 16911-2.
If a pre-investigation has been performed, the number of paired measurement points required for a
calibration is reduced.
An alternative calibration method has been added (method D) using linear regression and forcing the
regression line through the zero point.
6 Type testing, quality assurance level 1 data
6.1 Introduction
6.1.1 General
[6]
According to EN 14181 and EN 15267, the flow monitoring system shall consist of all necessary parts to
keep the flow monitor operating within a specified uncertainty. These components shall include, but are
not limited to, necessary air-purging systems and auxiliary equipment to control continued operation
within the stipulated uncertainty.
Either 6.1.2 or 6.1.3 applies as appropriate.
6.1.2 Requirements within the European Economic Area
The relevant performance characteristics of the AMS shall be documented by the manufacturer and/or his
European representative by suitability tests performed according to the relevant European Standards.
6.1.3 Requirements outside the European Economic Area
The relevant performance characteristics of the AMS shall be documented by the manufacturer by
suitability tests performed according to the relevant standards.
6.1.4 Conclusion
These tests are usually carried out in the framework of certification or type approval procedures according
[6]
to EN 15267, and the AMS delivered to the plant shall have the same characteristics as the tested devices.
The tests comprise of a separate laboratory test and a 3 month field test in a typical application.
The test report shall include the total AMS uncertainty calculated according to EN 14181 and ISO 14956.
ISO 16911-2:2013(E)
6.2 Performance criteria
The requirements for the test results are developed from EN 15267-3 and stated in Table 1 and Table 2.
EN 15267-3 requires the manufacturer to describe, and the test laboratory to assess, the quality
assurance level 3 (QAL3) functionality.
EN ISO 16911-2 also requires the manufacturer to describe and the test laboratory to assess the capability
of the AMS to be linearity tested as a part of the functional test. If another test, other than the linearity
test, is assessed and certified by a test laboratory, that test is sufficient as part of the functional test.
The manufacturer shall declare and quantify any influencing parameters known to affect instrument
uncertainty, e.g. gas temperature, change in specific mass and/or specific heat capacity, gas composition,
gas pressure, as well as any method of compensation.
Interference tests shall be performed and the sensitivity coefficients shall be calculated and reported
according to EN 15267-3.
Using test results from the type approval certificate according to EN 15267-3 and ISO 14956, the total
uncertainty, systematic and random, of the results obtained for the flow AMS shall be calculated and reported.
6.3 Flow reference material or procedure
Most volume flow rate monitors measure flow indirectly using an associated parameter, e.g. differential
pressure, heat loss or transit time, in which case a flow reference material or procedure is used to test
these parameters.
The part of the monitor not tested by the reference material or procedure shall be tested by a procedure
described by the manufacturer and assessed and documented during the type approval.
The test laboratory shall assess whether the flow reference procedure provided for testing the AMS
functionality challenges all or as much of the AMS as possible with a repeatable reference value and a
specified uncertainty, see Table 1 and 2.
Table 1 — Automated measuring system performance criteria in laboratory tests
Performance characteristic Performance criteria
Response time ≤60 s
a
Repeatability standard deviation at lower reference point ≤2,0 %
a
Repeatability standard deviation at upper reference point ≤2,0 %
a
Lack of fit ≤3,0 %
Lower reference point shift due to ambient temperature change from 20 °C within
a
≤5,0 %
specified range
Upper reference point shift due to ambient temperature change from 20 °C within
a
≤5,0 %
specified range
a
Influence of voltage at +15 % and at −10 % from nominal supply voltage ≤2,0 %
a
Influence of vibration ≤2,0 %
b
Assessment of QAL3 check capability Pass
b
Assessment of linearity check capability Pass
a
Percentage value as percentage of the upper limit of the certification range.
b
The test house shall assess the possibility for the test procedure as described in 6.2.
8 © ISO 2013 – All rights reserved

ISO 16911-2:2013(E)
Table 2 — Automated measuring system performance criteria in field tests
Performance characteristic Performance criteria
Coefficient of determination of calibration function, R ≥0,90
Response time ≤60 s
Period of unattended operation (maintenance interval) ≥8 days
a
Lower reference point drift within maintenance interval ≤2 %
a
Upper reference point drift within maintenance interval ≤4 %
Availability ≥95 %
Reproducibility, R ≤3,3 %
f
a
Percentage value as percentage of the upper limit of the certification range.
6.4 Quality assurance level 1 calculation
6.4.1 General
Either 6.4.2 or 6.4.3 applies as appropriate.
6.4.2 Requirements within the European Economic Area
The AMS shall be approved and certified according to EN 15267-3 and the additional requirements in
EN ISO 16911-2.
6.4.3 Requirements outside the European Economic Area
The AMS shall meet the requirements specified in EN 15267-3 and the additional requirements in
EN ISO 16911-2.
6.4.4 Conclusion
The instrument configuration shall be audited by the test laboratory during type testing, and this
auditing shall include the geometrical configuration, including measurement of the duct cross-sectional
area and any reference quantity with an influence on the flow monitoring result, e.g. changes in flow
profile, changes in temperature, changes in pressure, changes in gas composition, and contamination.
All of these influences shall be estimated within a combined expanded uncertainty, calculated as
described in ISO 14956.
The test laboratory shall assess the influence of the change in flow profile on the flow monitor reading.
NOTE This facilitates the end user to estimate the expected flow profile influence, when the result of the pre-
investigation is known.
6.5 Velocity check points and quality assurance level 3
EN 15267-3 requires the manufacturer to provide a description of the methodology used by the AMS to
determine whether it is operating according to its product specification. This is made up of AMS checks
(automatic or manual internal zero point or lower reference point and upper reference point), combined
with an additional procedure, if the instrument checks do not challenge the whole measurement chain.
The test laboratory shall assess whether the mechanism for determining the internal reference points,
being at zero or defined lower reference velocity and upper reference velocity points, is as comprehensive
as is practical for the measurement technique used. The internal control combined with a procedure
shall be capable of detecting instrument malfunction, including problems caused by contamination and
internal drift.
ISO 16911-2:2013(E)
The manufacturer shall provide details of this procedure in the instruction manual describing how to ensure
the correct operation of the parts of the measurement not tested by the internal reference point checks.
The QAL3 test shall be made up of the reference point checks and, if required, the results of the
inspection procedure.
7 Selection of automated measuring system location
7.1 General
The axial position of the AMS on the duct (normally vertical) as well as its circumferential position on
the duct perimeter may have a significant influence on the AMS performance.
It is strongly recommended that a pre-investigation be performed as described in Clause 8 in order to
characterize the flow so that the AMS can be located in a position where changes in the flow profile do
not adversely affect AMS performance.
NOTE To reduce costs, the pre-investigation can be done together with the investigation of the homogeneity
test required by EN 15259.
The pre-investigation also enables the operator to determine whether a point AMS, probe AMS or cross-
duct AMS measurement satisfies the uncertainty requirements of EN ISO 16911-2, see Table 2.
[5]
NOTE The EU Directive 2010/75/EU states in Article 38, Section 3, and in Article 48, Section 3, that “The
competent authority shall determine the location of the sampling or measurement points to be used for the
monitoring of emissions”.
This section is intended to be a guideline for operators to enable them to make a good engineering decision.
If more than one AMS is being used, the AMSs shall be mounted so that they do not interfere with one another.
7.2 Selection based upon pre-investigation
A pre-investigation shall be performed according to Clause 8.
The location shall be chosen to give a representative measurement that also minimizes influence of
changes in the flow profile on the flow measurement uncertainty.
The proposed location and monitoring path(s) shall be determined based upon the recorded change in
flow profile, quantified using the crest factor and skewness of the flow profile as described in Annex F.
The installer shall select the AMS measurement location in accordance with the instructions given by
the manufacturer or in consultation with the manufacturer’s representative. The operator is advised to
liaise with the competent authority to ensure this location meets with their approval.
7.3 Selection based upon a predictable flow profile
The position of an AMS may be decided without a pre-investigation if it can be positioned in a place where
the flow profile is fully developed and cannot change, and if it is accepted by the competent authority.
This is normally achieved if all of the following criteria are fulfilled:
— the monitoring point is at least 25 times the hydraulic diameter, away from any upstream disturbance,
and at least five times the hydraulic diameter from any downstream disturbance;
— the flow has a Reynolds number larger than 10 000;
— the duct has no movable dampers or guide vanes;
— the duct does not have multiple feeds;
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