SIST EN ISO 6416:2005
(Main)Hydrometry - Measurement of discharge by the ultrasonic (acoustic) method (ISO 6416:2004)
Hydrometry - Measurement of discharge by the ultrasonic (acoustic) method (ISO 6416:2004)
To collaborate with ISO/TC 113/SC 1 under the terms of the Vienna Agreement, to revise ISO 6416, which will specify the setting up and operation of an ultrasonic flow gauging station for the measurement of discharge in a river or other open channel. Also it will describe the basic principles on which the method is based.
Hydrometrie - Messung des Abflusses mit dem Ultraschallverfahren (akustisches Verfahren) (ISO 6416:2004)
Hydrométrie - Mesure du débit a l'aide de la méthode ultrasonique (acoustique) (ISO 6416:2004)
Hidrometrija – Merjenje pretoka z ultrazvočno (akustično) metodo (ISO 6416:2004)
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN ISO 6416:2005
01-november-2005
+LGURPHWULMD±0HUMHQMHSUHWRND]XOWUD]YRþQR DNXVWLþQR PHWRGR ,62
Hydrometry - Measurement of discharge by the ultrasonic (acoustic) method (ISO
6416:2004)
Hydrometrie - Messung des Abflusses mit dem Ultraschallverfahren (akustisches
Verfahren) (ISO 6416:2004)
Hydrométrie - Mesure du débit a l'aide de la méthode ultrasonique (acoustique) (ISO
6416:2004)
Ta slovenski standard je istoveten z: EN ISO 6416:2005
ICS:
17.120.20 Pretok v odprtih kanalih Flow in open channels
SIST EN ISO 6416:2005 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
---------------------- Page: 1 ----------------------
SIST EN ISO 6416:2005
---------------------- Page: 2 ----------------------
SIST EN ISO 6416:2005
EUROPEAN STANDARD
EN ISO 6416
NORME EUROPÉENNE
EUROPÄISCHE NORM
August 2005
ICS 17.120.20
English Version
Hydrometry - Measurement of discharge by the ultrasonic
(acoustic) method (ISO 6416:2004)
Hydrométrie - Mesure du débit à l'aide de la méthode Hydrometrie - Messung des Abflusses mit dem
ultrasonique (acoustique) (ISO 6416:2004) Ultraschallverfahren (akustisches Verfahren) (ISO
6416:2004)
This European Standard was approved by CEN on 11 July 2005.
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 Central Secretariat 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 Central Secretariat has the same status as the official
versions.
CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia,
Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36 B-1050 Brussels
© 2005 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 6416:2005: E
worldwide for CEN national Members.
---------------------- Page: 3 ----------------------
SIST EN ISO 6416:2005
EN ISO 6416:2005 (E)
Foreword
The text of ISO 6416:2004 has been prepared by Technical Committee ISO/TC 113 "Hydrometric
determinations" of the International Organization for Standardization (ISO) and has been taken
over as EN ISO 6416:2005 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 February 2006, and conflicting national
standards shall be withdrawn at the latest by February 2006.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Cyprus,
Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
Endorsement notice
The text of ISO 6416:2004 has been approved by CEN as EN ISO 6416:2005 without any
modifications.
2
---------------------- Page: 4 ----------------------
SIST EN ISO 6416:2005
INTERNATIONAL ISO
STANDARD 6416
Third edition
2004-07-01
Hydrometry — Measurement of discharge
by the ultrasonic (acoustic) method
Hydrométrie — Mesure du débit à l'aide de la méthode ultrasonique
(acoustique)
Reference number
ISO 6416:2004(E)
©
ISO 2004
---------------------- Page: 5 ----------------------
SIST EN ISO 6416:2005
ISO 6416:2004(E)
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but
shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In
the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.
© ISO 2004
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 copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2004 – All rights reserved
---------------------- Page: 6 ----------------------
SIST EN ISO 6416:2005
ISO 6416:2004(E)
Contents Page
Foreword. v
1 Scope. 1
2 Normative references . 1
3 Terms and definitions. 1
4 Applications. 1
4.1 Open channels . 1
4.2 Multiple channels . 2
4.3 Closed conduits . 2
5 Method of measurement. 3
5.1 Discharge. 3
5.2 Calculation of discharge from the transit-time measurement. 3
6 Flow velocity determination by the ultrasonic (transit time) method. 3
6.1 Principle . 3
6.2 Sound propagation in water. 6
7 Gauge configuration . 10
7.1 General. 10
7.2 Single-path systems . 11
7.3 Multi-path systems. 12
7.4 Crossed path systems. 12
7.5 Reflected-path systems. 14
7.6 Systems using transponders. 15
7.7 Systems using divided cross-sections. 16
7.8 Sloping paths . 17
8 Calculation of discharge . 17
8.1 Single-path systems . 17
8.2 Multi-path systems. 17
8.3 Systems with transducers in the channel . 21
9 System calibration . 21
9.1 General. 21
9.2 Single-path systems . 22
10 Site selection . 24
10.1 Practical constraints. 24
10.2 Physical constraints of the measurement site. 25
10.3 Physical constraints which are distant from the measurement site . 25
11 Site survey — Before design and construction. 26
11.1 General. 26
11.2 Visual survey . 26
11.3 Survey of the cross-section. 27
11.4 Survey of velocity distribution . 27
11.5 Survey of signal propagation. 28
11.6 Other survey activities. 28
12 Operational measurement requirements. 28
12.1 General. 28
12.2 Basic components of flow determination. 29
12.3 Water velocity determination. 29
12.4 Determination of water stage or depth . 29
© ISO 2004 – All rights reserved iii
---------------------- Page: 7 ----------------------
SIST EN ISO 6416:2005
ISO 6416:2004(E)
12.5 Channel width.30
13 Gauging station equipment.30
13.1 General .30
13.2 Design and construction of equipment.31
13.3 Reflectors .32
13.4 Civil engineering works .35
13.5 Signal timing and processing .35
13.6 System self-checking.37
13.7 Site-specific data (or site parameters) .38
13.8 Clock and calendar.38
13.9 System performance criteria.38
13.10 System output.40
13.11 Installation.40
13.12 Commissioning.41
13.13 Operating manual.41
13.14 Maintenance.41
14 Measurement uncertainties.43
14.1 General .43
14.2 Definition of uncertainty .43
14.3 Uncertainty in discharge .44
Bibliography.50
iv © ISO 2004 – All rights reserved
---------------------- Page: 8 ----------------------
SIST EN ISO 6416:2005
ISO 6416:2004(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 6416 was prepared by Technical Committee ISO/TC 113, Hydrometry, Subcommittee SC 1, Velocity area
methods.
This third edition cancels and replaces the second edition (ISO 6416:1992), which has been technically
revised.
© ISO 2004 – All rights reserved v
---------------------- Page: 9 ----------------------
SIST EN ISO 6416:2005
---------------------- Page: 10 ----------------------
SIST EN ISO 6416:2005
INTERNATIONAL STANDARD ISO 6416:2004(E)
Hydrometry — Measurement of discharge by the ultrasonic
(acoustic) method
1 Scope
This International Standard describes the establishment and operation of an ultrasonic (transit-time) gauging
station for the continuous measurement of discharge in a river, an open channel or a closed conduit. It also
describes the basic principles on which the method is based, the operation and performance of associated
instrumentation and procedures for commissioning.
It is limited to the “transit time of ultrasonic pulses” technique, and is not applicable to systems that make use
of the “Doppler shift” or “correlation” or “level-to-flow” techniques.
This International Standard is not applicable to measurement in rivers with ice.
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 772:1996, Hydrometric determinations — Vocabulary and symbols
ISO 4373:1995, Measurement of liquid flow in open channels — Water-level measuring devices
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 772 apply.
4 Applications
4.1 Open channels
4.1.1 The method is suitable for use in river flow measurement, a significant advantage being additional
freedom from siting constraints in comparison with other available techniques. In particular, the method does
not demand the presence of a natural control or the creation of a man-made control at the proposed gauge
location, as it does not rely upon the establishment of a unique relation between water level and discharge.
4.1.2 Gauges using the method are capable of providing highly accurate flow determinations over a range
of flows contained within a defined gauge cross-section. They are tolerant of the backwater effects created by
tides, downstream tributary discharges, downstream weed growth, reservoir or head-pond water level
manipulation, and periodic channel obstruction.
NOTE For locations subjected to significant bed level or profile instability, it may not be possible to use gauges.
© ISO 2004 – All rights reserved 1
---------------------- Page: 11 ----------------------
SIST EN ISO 6416:2005
ISO 6416:2004(E)
4.1.3 Use of the method usually creates no obstruction to navigation. It creates no significant hazard or loss
of amenity for other channel users or riparian interests. However, some species of fish may be sensitive to
some types of ultrasonic signal. The gauge can be designed to be physically unobtrusive.
4.1.4 For use in remote locations, the electronic equipment can be designed to operate from battery power.
To economise on power consumption, the system is usually set to sample the flow for short periods and to
return to a quiescent condition between samples. (see 10.1.3 and 13.9.5).
4.1.5 The method is not really suitable for use when the channel is covered with ice, because of the
difficulty of determining the cross-sectional area of the water. Although this is a limitation of use, the method
may still have value in determining water velocity under the ice, if transducers can be positioned in unfrozen
water.
4.2 Multiple channels
4.2.1 At locations where the total flow is divided between two or more physically separate channels, such
as under a multiple-arched bridge, the instrumentation can be configured to determine individual channel
flows separately and then to combine these to create a single unified determination of flow.
4.2.2 If flow may not readily be contained within a single well-defined cross-section, and in particular if there
is significant flow that bypasses the main gauge cross-section by way of an extensive flood plain, it may be
possible to subdivide the flood plain into a series of “channels” in which the flow can be measured.
4.2.3 A station designer may decide to provide a comprehensive flood-plain measurement capability by this
means or may, alternatively, simply provide a flow or velocity sampling facility. In the latter situation, gauged
cross-sections may be constructed in the flood plain. These do not normally provide total coverage, but merely
provide locations at which flood-plain flow can be sampled for subsequent examination and analysis.
4.2.4 It should be noted that systems designed to determine flood-plain flow may suffer from the practical
difficulties of
a) inability to commission the system due to there being no water in the measurement section,
b) maintenance of the section, including weed cutting, debris clearance and repair of vandalism.
4.3 Closed conduits
The ultrasonic method can also be applied to the measurement of flow in closed conduits, including both
storm-water and foul sewers, under both free-flowing and surcharged conditions.
For systems used in foul sewers, special attention should be paid to the following:
a) the source of the water, especially whether it is from an aeration tank or from a section of channel
containing aerators or from a hydro-electric plant. The air dissolved in the water from such sources may
cause bubbles to form, and these may inhibit the operation of the flow gauge (see 10.3.1);
b) possible aeration of the water caused by a hydraulic jump or weir upstream of the measurement section,
especially under storm conditions (see 10.3.1);
c) the design of transducer mountings, to eliminate the risk of fouling by grease, rags and paper;
d) the need for the system to meet local codes of practice for electrical equipment installed in potentially
explosive atmospheres. This usually requires a certified intrinsically safe design for both the transducers
(which can be piezo-electric sources of ignition) and for the electronic unit (see for example EN 50014);
e) the change in the flow computation algorithm when the conduit is surcharged.
2 © ISO 2004 – All rights reserved
---------------------- Page: 12 ----------------------
SIST EN ISO 6416:2005
ISO 6416:2004(E)
For foul sewers which are less than about 4 m in width, a high loading of suspended solids is unlikely to
present a serious problem of signal attenuation (see 6.2.3).
5 Method of measurement
5.1 Discharge
5.1.1 Discharge, as defined in ISO 772, is the volume of liquid flowing through a cross-section in a unit time.
3
It is usually denoted by the symbol q and expressed in cubic metres per second (m /s). The definition of
discharge is the product of the wetted cross-sectional area and the mean velocity vector perpendicular to it.
5.1.2 The measurement methods may either determine the bulk quantity discharge q directly, by measuring
the time taken to fill a tank of known volume, or the methods may be indirect and require calculation of the
discharge from measured flow velocities in all points of the wet cross-section. The latter are generally referred
to as “velocity-area methods”. In practice it is not possible to measure velocities at all points, and so the
velocity-area methods deal with only a limited number of measuring points.
The transit-time method is a velocity-area method using flow velocities which have been determined by the
equipment, and which are averaged along one or more lines which are usually, but not necessarily, horizontal.
5.2 Calculation of discharge from the transit-time measurement
5.2.1 Flow measurement by the ultrasonic transit-time technique is analogous to flow measurement by
current meters. However, while the most commonly used current-metering method is based on the estimation
of mean velocity at a series of verticals dispersed across the gauged cross-section, in the transit-time method
the velocity samples are horizontally orientated (and vertically distributed). In principle, flow can be computed
by exactly the same methods applied to a current meter gauging (see ISO 748). However, in practice, the
different graphical methods available do not lend themselves easily to automatic computation, and only the
arithmetic methods are useable.
5.2.2 Discharge can be computed, provided that a relation can be established between the estimated
(horizontally averaged) flow velocity and the mean cross-sectional velocity. If the measured velocity at a single
elevation is not sufficient to establish this relation, measurements at more elevations can be carried out. The
resulting samples of flow velocity can be vertically integrated to provide an estimate of mean cross-sectional
velocity.
5.2.3 Discharge calculation also requires the cross-sectional area of the water to be known. An ultrasonic
transit-time system will, therefore, normally be capable not only of making sample measurements of velocity,
but also of determining (or accepting a signal from some other device determining) water depth, and of storing
details of the relation between water depth and cross-sectional area. It will also normally be capable of
executing the mathematical functions necessary to compute flow from the relevant stored and directly
determined data.
6 Flow velocity determination by the ultrasonic (transit time) method
6.1 Principle
6.1.1 An ultrasonic pulse travels in a downstream direction faster than a similar pulse travels upstream. The
speed of a pulse of sound travelling diagonally across the flow in a downstream direction will be increased by
the velocity component of the water. Conversely, the speed of a sound pulse moving in the opposite direction
will be decreased. The difference in the transit time in the two directions can be used to resolve both the
velocity of sound in water as well as the component of the velocity along the path taken by the ultrasonic
pulses.
© ISO 2004 – All rights reserved 3
---------------------- Page: 13 ----------------------
SIST EN ISO 6416:2005
ISO 6416:2004(E)
Key
1 v component of water velocity along the path
path
2 v component of water velocity in the direction of the flow
line
3 direction of flow
4 channel width
5 ultrasonic path
A, B transducers
θ angle between the path and the direction of flow
y downstream distance between transducers
Figure 1 — Schematic illustrating the general principle
6.1.2 For the path between transducers A and B in Figure 1, the transit time for the ultrasonic pulses are:
t = L/(c − v cosθ ) and t = L/(c + v cosθ ) (1)
AB BA
where
t is the transit time from transducer A to B, in seconds;
AB
t is the transit time from transducer B to A, in seconds;
BA
L is the path length (distance between transducer A and transducer B), in metres;
c is the speed of sound in water, in metres per second;
v is the line velocity or the average velocity of the water across the channel in the direction of flow, in
line
metres per second;
θ is the angle between the path and direction of flow.
Resolving for line velocity:
v = L × (t − t ) / (t × t × 2 cosθ ) (2)
line AB BA AB BA
4 © ISO 2004 – All rights reserved
---------------------- Page: 14 ----------------------
SIST EN ISO 6416:2005
ISO 6416:2004(E)
6.1.3 The transit times in Equation (2) are for the water path only, and do not include the fixed delays due to
the travel times through the faces of the transducers and cables, delays in the transmitter and receiver circuits,
and delays in signal detection (which may be affected by signal distortion). These fixed delays do not affect
the transit-time difference (t − t ), but will affect the term (t × t ). This factor is of particular importance
AB BA AB BA
for small channels or where long cable runs to the transducers are required.
Typical delay times for the transducers and electronic circuits are between 4 µs and 20 µs.
The delay time for the cables is typically 1 µs per 200 m of cable, i.e. for 100 m each way, transmit and
receive.
Taking the signal delays into account, Equation (2) for the computed water velocity becomes:
v = L × (t − t ) / [(t − δ ) × (t − δ ) × 2 cosθ ] (3)
R F R F
where
t is the t
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.