ASTM D5242-21

Standard Test Method for Open-Channel Flow Measurement of Water with Thin-Plate Weirs

SIGNIFICANCE AND USE
5.1 Thin-plate weirs are reliable and simple devices that have the potential for highly accurate flow measurements. With proper selection of the shape of the overflow section a wide range of discharges can be covered; the recommendations in this test method are based on experiments with flow rates from about 0.008 ft 3/s (0.00023 m  3/s) to about 50 ft 3/s (1.4 m 3/s).  
5.2 Thin-plate weirs are particularly suitable for use in water and wastewater without significant amounts of solids and in locations where a head loss is affordable.
SCOPE
1.1 This test method covers measurement of the volumetric flow rate of water and wastewater in channels with thin-plate weirs. Information related to this test method can be found in Rantz (1)2 and Ackers (2).  
1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.  
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 14-Dec-2021
• ICS: 17.120.20 - Flow in open channels
• Technical Committee: D19 - Water
• Drafting Committee: D19.07 - Sediments, Geomorphology, and Open-Channel Flow

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D5242 − 21
Standard Test Method for
Open-Channel Flow Measurement of Water with Thin-Plate
1
Weirs
This standard is issued under the fixed designation D5242; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
4
1. Scope 2.2 ISO Standards:
ISO1438 FlowMeasurementinOpenChannelsUsingWeirs
1.1 This test method covers measurement of the volumetric
and Venturi Flumes—Part 1: Thin-Plate Weirs
flow rate of water and wastewater in channels with thin-plate
ISO 555 Liquid Flow Measurement in Open Channels,
weirs. Information related to this test method can be found in
Delusion Methods for Measurement of Steady Flow-
2
Rantz (1) and Ackers (2).
Constant Rate Injection Method
1.2 The values stated in inch-pound units are to be regarded
3. Terminology
as standard. The values given in parentheses are mathematical
conversions to SI units that are provided for information only
3.1 Definitions:
and are not considered standard.
3.1.1 For definitions of terms used in this standard, refer to
Terminology D1129.
1.3 This standard does not purport to address all of the
3.2 Definitions of Terms Specific to This Standard:
safety concerns, if any, associated with its use. It is the
3.2.1 crest, n—the bottom of the overflow section or notch
responsibility of the user of this standard to establish appro-
of a rectangular weir.
priate safety, health, and environmental practices and deter-
3.2.2 head, n—theheight of aliquidaboveaspecifiedpoint,
mine the applicability of regulatory limitations prior to use.
for example, the weir crest.
1.4 This international standard was developed in accor-
3.2.3 hydraulic jump, n—an abrupt transition from super-
dance with internationally recognized principles on standard-
critical flow to subcritical or tranquil flow.
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom- 3.2.4 nappe, n—the curved sheet or jet of water overfalling
mendations issued by the World Trade Organization Technical the weir.
Barriers to Trade (TBT) Committee.
3.2.5 notch, n—the overflow section of a triangular weir or
of a rectangular weir with side contractions.
2. Referenced Documents
3.2.6 primary instrument, n—the device (in this case the
3
2.1 ASTM Standards:
weir) that creates a hydrodynamic condition that can be sensed
D1129 Terminology Relating to Water
by the secondary instrument.
D2777 Practice for Determination of Precision and Bias of
3.2.7 scow float, n—an in-stream float for depth sensing,
Applicable Test Methods of Committee D19 on Water
usually mounted on a hinged cantilever.
D3858 Test Method for Open-Channel Flow Measurement
3.2.8 secondary instrument, n—in this case, a device that
of Water by Velocity-Area Method
measures the depth of flow (referenced to the crest) at an
appropriate location upstream of the weir plate. The secondary
instrument may also convert the measured depth to an indi-
1
This test method is under the jurisdiction of ASTM Committee D19 on Water
cated flow rate.
and is the direct responsibility of Subcommittee D19.07 on Sediments,
3.2.9 stilling well, n—a small free-surface reservoir con-
Geomorphology, and Open-Channel Flow.
Current edition approved Dec. 15, 2021. Published January 2022. Originally
nected through a constricted channel to the approach channel
approved in 1992. Last previous edition approved in 2013 as D5242 – 92 (2013).
upstreamoftheweirsothatadepth(head)measurementcanbe
DOI: 10.1520/D5242-21.
made under quiescent conditions.
2
The boldface numbers in parentheses refer to a list of references at the end of
the text.
3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
4
Standards volume information, refer to the standard’s Document Summary page on Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
the ASTM website. 4th Floor, New York, NY 10036, http://www.ansi.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

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D5242 − 21
3.2.10 subcritical flow, n—open channel flow in which the
average velocity is less than the square root of the product of
the average depth and the acceleration due to gravity; some-
times called tranquil flow.
3.2.11 submergence, n—a condition where the water level
on the downstream side of th
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D5242 − 92 (Reapproved 2013) D5242 − 21
Standard Test Method for
Open-Channel Flow Measurement of Water with Thin-Plate
1
Weirs
This standard is issued under the fixed designation D5242; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This test method covers measurement of the volumetric flowrate flow rate of water and wastewater in channels with thin-plate
2
weirs. Information related to this test method can be found in Rantz (1) and Ackers (2).
1.2 The values stated in inch-pound units are to be regarded as the standard. The SI units values given in parentheses are for
information only.mathematical conversions to SI units that are provided for information only and are not considered standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
3
2.1 ASTM Standards:
D1129 Terminology Relating to Water
D2777 Practice for Determination of Precision and Bias of Applicable Test Methods of Committee D19 on Water
D3858 Test Method for Open-Channel Flow Measurement of Water by Velocity-Area Method
4
2.2 ISO Standards:
ISO 1438 Flow Measurement in Open Channels Using Weirs and Venturi Flumes—Part 1: Thin-Plate Weirs
ISO 555 Liquid Flow Measurement in Open Channels, Delusion Methods for Measurement of Steady Flow-Constant Rate
Injection Method
3. Terminology
3.1 Definitions:
3.1.1 For definitions of terms used in this test method, standard, refer to Terminology D1129.
3.2 Definitions of Terms Specific to This Standard:
1
This test method is under the jurisdiction of ASTM Committee D19 on Water and is the direct responsibility of Subcommittee D19.07 on Sediments, Geomorphology,
and Open-Channel Flow.
Current edition approved Jan. 1, 2013Dec. 15, 2021. Published January 2013January 2022. Originally approved in 1992. Last previous edition approved in 20072013 as
D5242 – 92 (2007).(2013). DOI: 10.1520/D5242-92R13.10.1520/D5242-21.
2
The boldface numbers in parentheses refer to a list of references at the end of the text.
3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
4
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
D5242 − 21
3.2.1 crest—crest, n—the bottom of the overflow section or notch of a rectangular weir.
3.2.2 head—head, n—the height of a liquid above a specified point, for example, the weir crest.
3.2.3 hydraulic jump—jump, n—an abrupt transition from supercritical flow to subcritical or tranquil flow.
3.2.4 nappe—nappe, n—the curved sheet or jet of water overfalling the weir.
3.2.5 notch—notch, n—the overflow section of a triangular weir or of a rectangular weir with side contractions.
3.2.6 primary instrument—instrument, n—the device (in this case the weir) that creates a hydrodynamic condition that can be
sensed by the secondary instrument.
3.2.7 scow float—float, n—an in-stream float for depth sensing, usually mounted on a hinged cantilever.
3.2.8 secondary instrument—instrument, n—in this case, a device that measures the depth of flow (referenced to the crest) at an
appropriate location upstream of the weir plate. The secondary instrument may also convert the measured depth to an indicated
flowrate.flow rate.
3.2.9 stilling well—well, n—a small free-surface reservoir connected through a constricted channel to the approach channel
upstream of the weir so that a depth (head) measure
...