Full Description BS ISO 4359:2013+A1:2017 specifies methods for the measurement of flow in rivers and artificial channels under steady or slowly varying flow conditions, using certain types of standing-wave, or critical-depth, flumes.
A wide variety of flumes has been developed, but only those which have received general acceptance after adequate research and field testing, and which therefore do not require in situ calibration, are considered.
The flow conditions considered are uniquely dependent on the upstream head, i.e. subcritical flow must exist upstream of the flume, after which the flow accelerates through the contraction and passes through its critical depth (see Figure 1). The water level downstream of the structure is low enough to have no influence upon its performance.
This International Standard is applicable to three commonly used types of flumes, covering a wide range of applications, namely rectangular-throated, trapezoidal-throated and U-throated. Typical field installations are shown in Figure 2. Site conditions are important and Figure 3 shows acceptable velocity profiles in the approach channel.
Cross References:
ISO 772
ISO 26906
TS 25377
IEC 17025
TS 24154
ISO 4373
ISO 5168
ISO 748
ISO/IEC Guide 98-3
Incorporates the following:
Amendment, February 2018