ASTM: D5614: Open Channel Flow Measurement of Water

Summary
Analytes
Revision
Data and Sites

Official Method Name

Standard Test Method for Open Channel Flow Measurement of Water with Broad-Crested Weirs

Current Revision

Reapproved 1998. Current edition approved Sept. 15, 1994. Published November 1994.

Media

WATER

Instrumentation

Broad Crested Weir Measuring System

Method Subcategory

Physical

Method Source

ASTM

Citation

Annual Book of ASTM Standards, Section 11, Water and Environmental Technology, Volume 11.01, Water (I)

Brief Method Summary

In broad-crested weirs, the length of the horizontal crest in the direction of flow is large enough relative to the upstream head for essentially rectilinear critical flow to occur at some point along the crest. This ideally permits the flow rate to be obtained from a single measurement of the upstream head; a corrective coefficient must be applied in practice. This coefficient has been evaluated experimentally for square-edge weirs and can be determined analytically for rounded weirs.

Scope and Application

This test method covers measurement of the volumetric flow rate of water in open channels with two types of horizontal broad-crested weirs: those having a square (sharp) upstream corner and those having a well-rounded upstream corner.

Applicable Concentration Range

None.

Interferences

Broad-crested weirs are not suitable for use in sediment-laden streams that are carrying heavy bed loads. However, floating debris is readily passed, particularly by the rounded weir.
Broad-crested weirs cannot be used beyond submergence limits because insufficient data exist to document their performance. It is therefore necessary to adhere to the tailwater-level limitations described in this test method.

Quality Control Requirements

Sample Handling

Maximum Holding Time

Relative Cost

Greater than $400

Sample Preparation Methods

This method has 1 analyte associated with it.

Analyte	Detection Level	Bias	Precision	Pct False Positive	Pct False Negative	Spiking Level
Flow rate(E-11790) Flow rate Gas flow rate Hydraulic conductivity Leak rate Liquid flow rate Volumetric flow rate	N/A	N/A	N/A

Precision Descriptor Notes:	Determination of the precision and bias for this test method is not possible, both at the multiple and single operator level, due to the high degree of instability of open-channel flow. Both temporal and spatial variability of the boundary and flow conditions do not allow for a constant standard to be used for representative sampling. A minimum bias, measured under ideal conditions, is related directly to the bias of the equipment used.
Detection Level Note:	None.

Precision Descriptor Notes:

Determination of the precision and bias for this test method is not possible, both at the multiple and single operator level, due to the high degree of instability of open-channel flow. Both temporal and spatial variability of the boundary and flow conditions do not allow for a constant standard to be used for representative sampling. A minimum bias, measured under ideal conditions, is related directly to the bias of the equipment used.

Detection Level Note:

None.

Revision	PDF/Link
Reapproved 1998. Current edition approved Sept. 15, 1994. Published November 1994.

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ASTM: D5614: Open Channel Flow Measurement of Water

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