ASTM D1941-21

Standard Test Method for Open Channel Flow Measurement of Water with the Parshall Flume

SIGNIFICANCE AND USE
5.1 Flume designs are available for throat sizes of 1 in. (2.54 cm) to 50 ft (15.2 m) which cover maximum flows of 0.2 to 3000 ft3/s (0.0057 to 85 m3/s) (1) and (2).4 They can therefore be applied to a wide range of flows, with head losses that are moderate.  
5.2 The flume is self-cleansing for moderate solids transport and therefore is suited for wastewater and flows with sediment.
SCOPE
1.1 This test method covers measurement of the volumetric flowrate of water and wastewater in open channels with the Parshall flume.  
1.1.1 Information related to this test method can be found in ISO 1438 and ISO 4359.  
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: 13.060.30 - Sewage water
• 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: D1941 − 21
Standard Test Method for
Open Channel Flow Measurement of Water with the Parshall
1
Flume
This standard is issued under the fixed designation D1941; 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.
3
1. Scope 2.2 ISO Standards:
ISO 555-2:1987 Liquid Flow Measurements in Open
1.1 This test method covers measurement of the volumetric
Channels—Dilution Methods for Measurement of Steady
flowrate of water and wastewater in open channels with the
Flow—Constant Rate Injection Method
Parshall flume.
ISO 1438:2017 Liquid Flow Measurement in Open Chan-
1.1.1 Information related to this test method can be found in
nels Using Thin-Plate Weirs
ISO 1438 and ISO 4359.
ISO 4359:2013 Liquid Flow Measurement in Open
1.2 The values stated in inch-pound units are to be regarded
Channels—Rectangular Trapezoidal and U-shaped
as standard. The values given in parentheses are mathematical
Flumes
conversions to SI units that are provided for information only
and are not considered standard. 3. Terminology
1.3 This standard does not purport to address all of the 3.1 Definitions:
safety concerns, if any, associated with its use. It is the 3.1.1 For definitions of terms used in this standard, refer to
responsibility of the user of this standard to establish appro- Terminology D1129.
priate safety, health, and environmental practices and deter-
3.2 Definitions of Terms Specific to This Standard:
mine the applicability of regulatory limitations prior to use.
3.2.1 free flow, n—a condition where the flowrate is gov-
1.4 This international standard was developed in accor-
erned by the state of flow at the crest overfall and hence can be
dance with internationally recognized principles on standard-
determined from a single upstream depth measurement.
ization established in the Decision on Principles for the
3.2.2 head, n—theheightofaliquidaboveaspecifiedpoint.
Development of International Standards, Guides and Recom-
3.2.2.1 Discussion—That is, the flume crest.
mendations issued by the World Trade Organization Technical
3.2.3 hydraulic jump, n—an abrupt transition from super-
Barriers to Trade (TBT) Committee.
critical to subcritical flow, accompanied by considerable tur-
2. Referenced Documents
bulence or gravity waves, or both.
2
2.1 ASTM Standards: 3.2.4 normal depth, n—the uniform depth of flow for a
D1129 Terminology Relating to Water given flowrate in a long open channel of specific shape,
D2777 Practice for Determination of Precision and Bias of roughness, and slope.
Applicable Test Methods of Committee D19 on Water
3.2.5 primary instrument, n—the device that creates a hy-
D3858 Test Method for Open-Channel Flow Measurement
drodynamic condition that can be sensed by the secondary
of Water by Velocity-Area Method
instrument.
3.2.5.1 Discussion—Inthisexample,theprimaryinstrument
is the flume.
1
This test method is under the jurisdiction of ASTM Committee D19 on Water
3.2.6 scow float, n—an in-stream flat for depth sensing that
and is the direct responsibility of Subcommittee D19.07 on Sediments,
Geomorphology, and Open-Channel Flow.
is usually mounted on a hinged cantilever.
Current edition approved Dec. 15, 2021. Published February 2022. Originally
3.2.7 secondary instrument, n—a device which measures
approved in 1962. Last previous edition approved in 2013 as D1941 – 91 (2013).
DOI: 10.1520/D1941-21.
the depth of flow at an appropriate location in the flume.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
3
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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D1941 − 21
3.2.7.1 Discussion—The secondary instrument may also secondary device can range from a simple scale for manual
convert the measured depth to an indicated flow rate. readings to an instrument which continuously senses the depth,
converts it to flowrate, and provides a readout or record of
3.2.8 stilling well, n—a small reservoir connected through a
instantaneous flowrate or totalized flow, or both.
constricted passage to the main channel, that is, the flume, so
that a
...

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: D1941 − 91 (Reapproved 2013) D1941 − 21
Standard Test Method for
Open Channel Flow Measurement of Water with the Parshall
1
Flume
This standard is issued under the fixed designation D1941; 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 of water and wastewater in open channels with the Parshall
flume.
1.1.1 Information related to this test method can be found in ISO 1438 and ISO 4359.
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.
2. Referenced Documents
2
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
3
2.2 ISO Standards:
ISO 555555-2:1987 Liquid Flow Measurements in Open Channels—Dilution Methods for Measurement of Steady Flow—
Constant Rate Injection Method
ISO 14381438:2017 Liquid Flow Measurement in Open Channels Using Thin-Plate Weirs and Venturi Flumes
ISO 43594359:2013 Liquid Flow Measurement in Open Channels—Rectangular Trapezoidal and U-shaped Flumes
3. Terminology
3.1 Definitions—Definitions: For definitions of terms used in this test method, refer to Terminology D1129.
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 2013February 2022. Originally approved in 1962. Last previous edition approved in 20072013
as D1941 – 91 (2007).(2013). DOI: 10.1520/D1941-91R13.10.1520/D1941-21.
2
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.
3
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 ----------------------
D1941 − 21
3.1.1 For definitions of terms used in this standard, refer to Terminology D1129.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 free flow—flow, n—a condition where the flowrate is governed by the state of flow at the crest overfall and hence can be
determined from a single upstream depth measurement.
3.2.2 head—head, n—the height of a liquid above a specified point; that is, the flume crest.point.
3.2.2.1 Discussion—
That is, the flume crest.
3.2.3 hydraulic jump—jump, n—an abrupt transition from supercritical to subcritical flow, accompanied by considerable
turbulence or gravity waves, or both.
3.2.4 normal depth—depth, n—the uniform depth of flow for a given flowrate in a long open channel of specific shape, roughness,
and slope.
3.2.5 primary instrument—instrument, n—the device (in this case, the flume) that creates a hydrodynamic condition that can be
sensed by the secondary instrument.
3.2.5.1 Discussion—
In this example, the primary instrument is the flume.
3.2.6 scow float—float, n—an in-stream flat for depth sensing that is usually mounted on a hinged cantilever.
3.2.7 secondary instrument—instrument, n—in this case, a device which measures the depth of flow at an appropriate location in
the flume. The secondary instrument ma
...