ISO INTERNATIONAL 9826 STANDARD First edition 1992-09-15 Measurement of liguid ffow in open channels Parshall and SANllRI flumes Mesure de debit des liquides dans les canaux decouverts -- Canaux jaugeurs Parshall et SANiR! Reference number ISO 9826:1992(E) Not for Resale without license from IHS ISO 9826:1992(E) Foreword IsO (the International Organization for Standardization) is a worldwide federation of national standards bodies (IsO member bodies). The work of preparing International Standards is normally carried out through iso technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations. govern- mental and non-governmental, in liaison with iso, also take part in the work. Iso collaborates closely with the International Electrotechnical Commission (iEC) on all matters of electrotechnical standardization. Draft International Standards adopted by the technical committees are national Standard requires approval by at least 75 % of the member bodies casting a vote. International Standard Iso 9826 was prepared by Technical Committee ISO/TC Measurement liquid flow in open channels, 113 of Sub- Committee SC 2, Notches, weirs and flumes. permission in writing from the pubiisher International Organization for Standardization Case Postale 56· CH-1211 Geneve 20 : Switzerland Printed in Switzerland ii Not for Resale d without license from IHS ISO 9826:1992(E) INTERNATIONAL STANDARD Measurement of liquid flow in open channels - Parshall and SANIIRI flumes Scope Selection of flume type 4 This International Standard specifies methods of liquid flow measurement in open channels (particu- larly in irrigation canals) under steady or slowly 4.1 The choice as to whether a Parshall or a varying flow conditions, using Parshall and SANiRi SANlRl flume should be used depends on several flumes. factors such as the range of discharge to be meas- ured, the head available, the moduiar limit and the These flumes are designed to operate under both maximum submergence ratio, the channei or canal free-flow and submergence conditions. characteristics, the amount of head loss which can be allowed through the flume, the possibility of 2 Normative reference deepening the bed and providing a drop therein, the accuracy of measurement required, whether or not the flow carries sediment, the operating conditions The following standard contains provisions which. that necessitate the use of either stationary or port- through reference in this text, constitute provisions able flumes, and economic considerations. of this International Standard. At the time of publi- cation, the edition indicated was valid. All standards are subject to revision, and parties to agreements based on this International Standard are encour- 4.2 Parshall flumes have a rectangular cross- aged to investigate the possibilityof applying the most recent edition of the standard indicated below. section and a wide range of throat widths varying Members of IEC and ISO maintain registers of cur- from very small (0.025 4 m) to large (15 m and rently valid International Standards. greater). Medium-sized Parshall flumes, with throat widths ISO 772:1988, Liquid flow measurement in open between about 0,15 m and about 2,5m, which are channels -- Vocabulary and symbois. suitable for measuring discharges in the range from 0,001 5 m'/s to 4,0 m"/s are those most commonly Definitions and symbols 3 used for flow measurements: they are thus recom- For the purposes of this International Standard, the structures" definitions and symbols given in ISO 772 and the following definitions apply. about 3 m and about 15 m, the design of which varies depending on the size of the flume, are suit- Parshall flume: Measuring flume having a con 3.1 able for measuring discharges in the range from verging entrance section with a level floor, a short 0.75 m*/s to 93 m*/s. throat section with a fl