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ISO 18481:2017

Current
Current

The latest, up-to-date edition.

Hydrometry — Liquid flow measurement using end depth method in channels with a free overfall
Available format(s)

Hardcopy , PDF , PDF 3 Users , PDF 5 Users , PDF 9 Users

Language(s)

English

Published date

12-08-2017

ISO 18481:2017 specifies a method for the estimation of the sub-critical flow of clear water in a smooth, essentially horizontal channel (or a gently sloping channel), abruptly discontinued at bottom by a hydraulic structure, with a vertical drop and discharging freely. Such an overfall forms a control section and offers a means for the estimation of flow using the end depth measurement method. A wide variety of channel cross-sections with overfall have been studied, but only those which have received general acceptance after adequate research and testing, and therefore do not require in situ calibration, are considered. This document covers channels with the following types of cross-sections:

a) rectangular with confined and unconfined nappe;

b) trapezoidal;

c) triangular;

d) circular;

e) parabolic.

The flow at the brink is curvilinear; therefore, the measured depth at the drop is not equal to the critical depth as computed by the principle based on assumption of parallel flow. However, the end depth and the critical depth (as in the case of the assumption of parallel flow) have unique relation, which is used to estimate the flow through these structures.

Committee
ISO/TC 113/SC 2
DevelopmentNote
Supersedes ISO/DIS 18481, ISO 3847 and ISO 4371. (12/2017)
DocumentType
Standard
Pages
20
PublisherName
International Organization for Standardization
Status
Current
Supersedes

Standards Relationship
AS 3778.4.10:2022 Identical
BS ISO 18481:2017 Identical

ISO 4373:2008 Hydrometry Water level measuring devices
ISO 772:1996 Hydrometric determinations — Vocabulary and symbols

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