EN ISO 748:2007

Hydrometry - Measurement of liquid flow in open channels using current-meters or floats (ISO 748:2007)

ISO 748:2007 specifies methods for determining the velocity and cross‑sectional area of water flowing in open channels without ice cover, and for computing the discharge therefrom.
ISO 748:2007 covers methods of employing current‑meters or floats to measure the velocities. It deals only with single measurements of the discharge; the continuous recording of discharges over a period of time is covered in ISO 1100-1 and ISO 1100-2.

Hydrometrie - Durchflussmessung in offenen Gerinnen mittels Fließgeschwindigkeitsmessgeräten oder Schwimmern (ISO 748:2007)

Diese Norm legt Verfahren zur Bestimmung von Geschwindigkeit und Querschnittsfläche von Wasser, das ohne Eisdecke durch offene Gerinne fließt, und für die Berechnung des daraus resultierenden Durchflusses fest.
Sie umfasst Verfahren, bei denen die Geschwindigkeiten mit FließgeschwindigkeitsmessgerätFließgeschwindigkeitsmessgeräten und Schwimmern gemessen werden. Obwohl diese Messungen in den meisten Fällen für die Bestimmung der Abflusstafel einer Pegelstation vorgesehen sind, befasst sich diese Norm nur mit Einzelmessungen des Durchflusses; die Daueraufzeichnung von Durchflüssen über einen Zeitraum wird in ISO 1100 1 und ISO 1100 2 behandelt.
ANMERKUNG   Die Verfahren zur Bestimmung von Geschwindigkeit und Querschnittsfläche von Wasser, das mit einer Eisdecke bedeckt durch offene Gerinne fließt, werden in ISO 9196 festgelegt.

Hydrométrie - Mesurage du débit des liquides dans les canaux découverts au moyen de débitmètres ou de flotteurs (ISO 748:2007)

L'ISO 748:2007 spécifie des méthodes permettant de déterminer la vitesse et l'aire de la section droite d'un écoulement d'eau en chenal non couvert par la glace et de calculer le débit à partir des résultats des mesurages.
Elle couvre les méthodes faisant usage de moulinets ou de flotteurs destinés au mesurage des vitesses. Il est à noter que, bien que dans certains cas ces mesurages soient entrepris pour déterminer la relation hauteur-débit d'une station hydrométrique, l'ISO 748:2007 ne traite que de simples mesurages du débit; l'enregistrement en continu des débits durant une certaine période fait l'objet de l'ISO 1100‑1 et de l'ISO 1100‑2.

Hidrometrija - Merjenje pretoka tekočin v odprtih kanalih z uporabo hidrometričnih kril ali plavačev (ISO 748:2007)

General Information

• Status: Withdrawn
• Publication Date: 14-Oct-2007
• Withdrawal Date: 30-Nov-2021
• ICS: 17.120.20 - Flow in open channels
• Technical Committee: CEN/TC 318 - Hydrometry
• Drafting Committee: CEN/TC 318 - Hydrometry
• Current Stage: 9960 - Withdrawal effective - Withdrawal
• Completion Date: 01-Dec-2021
• Ref Project: SIST EN ISO 748:2008 - Hydrometry - Measurement of liquid flow in open channels using current-meters or floats (ISO 748:2007)

Relations

• Replaces: EN ISO 748:2000 - Measurement of liquid flow in open channels - Velocity-area methods (ISO 748:1997)
• Effective Date: 22-Dec-2008
• Replaced By: EN ISO 748:2021 - Hydrometry - Measurement of liquid flow in open channels - Velocity area methods using point velocity measurements (ISO 748:2021)
• Effective Date: 08-Dec-2021

Standards Content (Sample)

SLOVENSKI STANDARD
01-januar-2008
1DGRPHãþD
SIST EN ISO 748:2001
+LGURPHWULMD0HUMHQMHSUHWRNDWHNRþLQYRGSUWLKNDQDOLK]XSRUDERKLGURPHWULþQLK
NULODOLSODYDþHY,62
Hydrometry - Measurement of liquid flow in open channels using current-meters or floats
(ISO 748:2007)
Hydrometrie - Durchflussmessung in offenen Gerinnen mittels
Fließgeschwindigkeitsmessgeräten oder Schwimmern (ISO 748:2007)
Hydrométrie - Mesurage du débit des liquides dans les canaux découverts au moyen de
débitmetres ou de flotteurs (ISO 748:2007)
Ta slovenski standard je istoveten z: EN ISO 748:2007
ICS:
17.120.20 Pretok v odprtih kanalih Flow in open channels
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN ISO 748
NORME EUROPÉENNE
EUROPÄISCHE NORM
October 2007
ICS 17.120.20 Supersedes EN ISO 748:2000
English Version
Hydrometry - Measurement of liquid flow in open channels using
current-meters or floats (ISO 748:2007)
Hydrométrie - Mesurage du débit des liquides dans les Hydrometrie - Durchflussmessung in offenen Gerinnen
canaux découverts au moyen de débitmètres ou de mittels Fließgeschwindigkeitsmessgeräten oder
flotteurs (ISO 748:2007) Schwimmern (ISO 748:2007)
This European Standard was approved by CEN on 21 September 2007.
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 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 Management Centre has the same status as the
official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2007 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 748:2007: E
worldwide for CEN national Members.

Contents Page
Foreword.3

Foreword
This document (EN ISO 748:2007) has been prepared by Technical Committee ISO/TC 113 "Hydrometric
determinations" in collaboration with 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 April 2008, and conflicting national standards shall be withdrawn at the
latest by April 2008.
This document supersedes EN ISO 748:2000.
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, Cyprus, Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.
Endorsement notice
The text of ISO 748:2007 has been approved by CEN as a EN ISO 748:2007 without any modification.

INTERNATIONAL ISO
STANDARD 748
Fourth edition
2007-10-15
Hydrometry — Measurement of liquid
flow in open channels using current-
meters or floats
Hydrométrie — Mesurage du débit des liquides dans les canaux
découverts au moyen de débitmètres ou de flotteurs

Reference number
ISO 748:2007(E)
©
ISO 2007
ISO 748:2007(E)
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ISO 748:2007(E)
Contents Page
Foreword. v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 1
4 Principle of the methods of measurements. 1
5 Selection and demarcation of site . 2
5.1 Selection of site . 2
5.2 Demarcation of site. 3
6 Measurement of cross-sectional area . 3
6.1 General. 3
6.2 Measurement of width. 3
6.3 Measurement of depth. 4
7 Measurement of velocity. 5
7.1 Measurement of velocity using current-meters. 5
7.1.1 Rotating-element current-meters . 5
7.1.2 Electromagnetic current-meters . 5
7.1.3 Measurement procedure . 5
7.1.4 Oblique flow . 6
7.1.5 Determination of the mean velocity in a vertical . 7
7.1.6 Errors and limitations. 10
7.2 Measurement of velocity using floats. 11
7.2.1 General. 11
7.2.2 Selection of site . 11
7.2.3 Measuring procedure . 11
7.2.4 Types of float. 11
7.2.5 Determination of velocity. 12
7.2.6 Main sources of error . 13
8 Computation of discharge . 13
8.1 General. 13
8.2 Graphical method . 13
8.2.1 Depth-velocity-integration . 13
8.2.2 Velocity-area integration method (velocity-contour method) . 14
8.3 Arithmetic methods . 16
8.3.1 Mean-section method. 16
8.3.2 Mid-section method. 16
8.4 Independent vertical method. 17
8.5 Mean-section method — Horizontal planes . 20
8.6 Determination of discharge from surface-float velocity measurements . 20
8.7 Determination of discharge for variations of water level . 22
8.7.1 General. 22
8.7.2 Computation of discharge . 22
8.7.3 Computation of mean water level . 22
9 Uncertainties in flow measurement . 23
9.1 General. 23
9.2 Definition of uncertainty. 23
9.3 Method of calculating the uncertainty in discharge by measurement of velocity by
current-meter. 24
9.3.1 General. 24
ISO 748:2007(E)
9.3.2 Contributory uncertainties. 24
9.3.3 Example. 26
9.3.4 Combined uncertainty . 26
9.4 Method of calculating the uncertainty in discharge by measurement of velocity using
floats. 27
9.4.1 General . 27
9.4.2 Contributory uncertainties. 27
9.4.3 Combined uncertainty in discharge. 28
9.4.4 Example. 28
Annex A (informative) Correction for sag, pull, slope and temperature in measurement of cross-
section width by tape or wire.
...