1、 STD-BSI BS IS0 83b-ENGL 1979 ib24bb 077Y7b8 277 m BRITISH STANDARD Hydrometric determinations - Flow measurements in open channels using structures - Guidelines for the selection of structure ICs 17.120.20 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGm LAW BS IS0 3368:1999 BS IS0
2、 83681999 National foreword This British Standard reproduces verbatim IS0 8368: 1999 and implements it as the UK national standard It supersedes BS 3680, Part 4, Section 4fi1986 which is withbw, and which was identical with IS0 8368: 1985. The UK participation in its preparation was entrusted by Tec
3、hnical Committee CPV113, Hydrometry, to Subcommittee CPI/l13/2, Notches, weirs and flumes, which has the responsibility to: - aid enquirers to understand the text; - present to the responsible internationallEuropean committee any enquiries on the interpretation, or proposals for change, and keep the
4、 UK interests informed; - monitor related international and European developments and promulgate them in the UK A list of organizations represented on this subcommittee can be obtained on request to its secretary. Since the final draft (FDIS) of IS0 8638 was approved, the UK committee has noted an i
5、nconsistency, between EO 8368 and IS0 4377. In order to correct this inconsistency, the UK committee has advised ISOAT 113/SC 2 accordingly, but meanwhile the following amendment should be made to BS IS0 8368: 1999. In Table 1, in the row for “Flat-V weirs“, in the column headed “Limitations“, pleas
6、e delete u2,53) and substitute “Vary“. Cross-references The British Standards which implement international or European publications referred to in this document may be found in the BSI Standards Catalogue under the section entitled “Inteniational Standards Correspondence Index“, or by using the “Fi
7、nd“ facility of the BSI Standards Electronic Catalogue. A British Standard does not purport to include all the necessary provisions of a conkact Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal
8、obligations. Summary of pages This document comprises a front cover, an inside front cover, the IS0 title page, pages ii and iii, a blank page, pages 1 to 11 and a back cover. The BSI copyright notice displayed in this document indicates when this document was last issued. This British Standard, hav
9、ing been prepared under the direction of the Sector Board for Materials and Chemicals, was published under the authority of the Standards Committee and comes into effect on 15 September 1999 Amendments issued since publication Amd. No. Date Comments. I I O BSI 09-1999 ISBN O 680 32303 X INTERNATIONA
10、L STANDARD IS0 8368 Second edition 1999-04-01 Hydrometric determinations - Flow measurements in open channels using structures - Guidelines for selection of structure Dterminations hydromtriques - Mesure de dbit dans les canaux dcouverts au moyen de structures - Lignes directrices pour le choix des
11、structures STD-BSI BS IS0 8358-ENGL 1919 U lb24bb9 0794773 Ab3 BS IS0 8368:1999 Contents 1 Scope 1 2 Normative references 1 3 Terms, definitions and symbols . 2 4 Types of structure 2 5 Factors affecting choice . 3 5.1 General . 3 5.2 Purpose 3 5.3 Range of flow 3 5.4 Afflux 3 5.5 Size and nature of
12、 channel 6 5.6 Channel slope and sediment load . 6 5.7 Operation and maintenance 6 5.8 Passage of fish 6 5.9 cost 7 6 Recommendations . 7 6.1 Thin-plate weirs . 7 6.2 Broad-crested weirs . 7 6.3 Triangular-profile weirs 8 6.4 Streamlined triangular-profile weirs . 8 6.5 Flat-V weirs 8 6.6 Compound g
13、auging structures . 8 6.7 Trapezoidal-profile weirs . 8 6.8 Vertical underflow gates and radial gates 9 6.9 End-depth method 9 6.10 Flumes . 9 7 Parameters governing choice of structures . 9 II ST3.6SI BS IS0 83bA-ENGL 1477 111 LbZLibbS 07i1772 7TT BS IS0 8368:1999 Foreword IS0 (the International Or
14、ganization for Standardization) is a worldwide federation of national standards bodies (IS0 member bodies). The work of preparing International Standards is normally carried out through IS0 technical committees. Each member body interested in a subject for which a technical committee has been establ
15、ished has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. IS0 collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardizati
16、on. International Standards are drafted in accordance with the rules given in the ISOAEC Directives, Part 3. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 Oh
17、of the member bodies casting a vote. International Standard IS0 8368 was prepared by Technical Committee ISOTTC 1 13, Hydrometric detemhations, Subcommittee SC 2, Notches, weis and flumes. This second edition cancels and replaces the first edition (IS0 8368:1985). This second edition of IS0 8368 was
18、 prepared in order to bring the techniques described up to date. The format has been improved to make the information easier to interpret. iii STD-BSI BS IS0 83bD-ENGL 1977 LbZibb7 0794773 b3b H BS IS0 8368:1999 Hydrometric determinations - Flow measurements in open channels using structures - Guide
19、lines for selection of structure 1 Scope This Intemational Standard gives guidelines for selection of a particular type of flow-gauging Structure for measurement of liquid flow in open channels. It sets out the factors, and summarizes the parameters which may influence such a selection. NOTE In gene
20、ral, a flow-gauging structure is used when high accuracy is required for continuous records of flow. 2 Normative references The following normative documents contain provisions which, through reference in this text, constitute provisions of this International Standard. For dated references, subseque
21、nt amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this Intemational Standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents listed below. For undated references, the latest
22、 edition of the normative document referred to applies. Members of IEC and IS0 maintain registers of currently valid Intemational Standards. IS0 772, Hydrometric determinations - Vocabulaty and symbols. IS0 1438-1, Water flow measurement in open channels using weirs and Venturi flumes - Pad 7: Thin-
23、plate weirs. IS0 3846, Liquid flow measurement in open channels by weirs and flumes - Rectangular broad-crested weirs. IS0 3847, Liquid flow measurement in open channels by weirs and flumes - End-depth method for estimation of flow in rectangular channels with a free overfall. IS0 4359, Liquid flow
24、measurement in open channels - Rectangular, trapezoidal and U-shaped flumes. IS0 4360, Liquid flow measurement in open channels by weirs and flumes - Triangular-profile weirs. IS0 4362, Measurement of liquid flow in open channels - Trapezoidal profile weirs. IS0 4371, Measurement of liquid flow in o
25、pen channels by weirs and flumes - End depth method for estimation of flow in non-rectangular channels with a free overfall (approximate method). IS0 4374, Liquid flow measurement in open channels - Round-nose horizontal broad-crested weirs. IS0 4377, Liquid flow measurement in open channels - Flat-
26、V weirs. IS0 8333, Liquid flow measurement in open channels by weirs and flumes - V-shaped broad-crested weirs. IS0 9826:1992, Measurement of liquid flow in open channels - Parshall and SANIIRI flumes. IS0 9827, Measurement of liquid flow in open channels by weirs and flumes - Streamlined triangular
27、-profile weirs. IS0 13550 , Hydrometric determinations - Flow measurements in open channels using structures - Use of vertical underflow gates and radial gates. IS0 141 39, Hydrometric determinations - Flow measurements in open channels using structures - Compound gauging structures. 1 STD-GSI BS IS
28、0 63bB-ENGL 1199 JR 1b2iibb9 079Y77Li 572 D BS IS0 8368:1999 3 Terms, definitions and symbols For the purposes of this International Standard, the terms, definitions and symbols together with the corresponding units of measurement given in IS0 i72 apply. 4 Types of structure The following types of s
29、tructure can be used for the purpose of liquid flow measurement: a) thin-plate weirs: 1) rectangular; 2) V-notch. b) broad-crested weirs: 1) round-nose horizontal; 2) rectangular horizontal; 3) V-shaped. c) triangular-profile weirs. d) streamlined triangular-profile weirs. e) flat-V weirs. f) flumes
30、: 1) rectangular; 2) trapezoidal: 3) U-throated; 4) Parshall and SANIIRI. g) end-depth method: 1) rectangular channel; 2) non-rectangular channel (approximate method). h) trapezoidal-profile weirs. i) compound gauging structures. j) vertical underflow gates and radial gates. Diagrams showing the con
31、struction of a particular type of flow-gauging structure are given in the appropriate International Standard listed in clause 2. 2 STDeBSI BS IS0 BgLB-tNGL 1979 111 lb24bb3 0799775 Li09 9 BS IS0 8368:1999 5 Factors affecting choice 5.1 General The factors which affect choice can be considered under
32、the following headings: a) purpose; b) range of flow; c) afflux; d) size and nature of channel; e) channel slope and sediment load; f) operation and maintenance; g) environmental impact; h) passage of fish; i) cost. 5.2 Purpose Table 1 tabulates the various structures and indicates some of the purpo
33、ses for which they may be applicable, together with guidelines to their limitations. The purpose for which the structure is required will determine the range of flows and accuracies which is necessary. The accuracy in a single determination of discharge depends upon the estimation of the component u
34、ncertainties involved. In broad terms, thin-plate weirs will have a range of uncertainties from 1 Oh to 4 70, flumes and certain types of weirs will have a range from 2 O/O to 5 o/o and end methods and other weirs will have a range from 4 Yo to 10 Yo. Deviations from the construction, installation o
35、r use as laid down in the appropriate International Standard will result in measurement errors . 5.3 Range of flow It is necessary to consider the relation between maximum flow and minimum flow when deciding which type of structure to use, and an indication of the range of some typical structures is
36、 given in Table 2. For the best overall accuracy over a wide range of small discharges, a thin-plate V-notch weir should be used in preference to a thin-plate rectangular notch or rectangular full-width weir. For a wide range of larger discharges, a trapezoidal flume, a flat4 weir or a triangular-pr
37、ofile weir should be used in preference to a broad-crested weir, free overfall or rectangular-throat flume. 5.4 Afflux The rise in level immediately upstream of, and due to, a structure may interfere with the flow system and cause drainage problems, or limit the effectiveness of irrigation systems,
38、or cause extra pumping costs. In addition, the aquatic habitat upstream of the structure may be adversely affected. A number of structures have been developed with high coefficients of discharge and whose accuracy is relatively unimpaired by high submergence ratios. The triangular- profile and flat-
39、V weirs, and flumes are examples of this type of structure. 3 STD-BSI BS IS0 83bA-ENGi Sl7 m LbZLibL 074477b 3Li5 % Thin-plate weirs IS0 1438-1 1 to4 2) 23) Laboratory, pump tests, sediment free water small streams, and for use in hydraulic: laboratories. Broad-crested weirs Broad-crested weirs are
40、best used in rec a) rectangular profile IS0 3846 66 70 1,53) tangular channels, but they can be used wit1 3 to 5 80 % 1,s 3) good accuracy in non-rectangular channels if i b) round-nose horizontal IS0 4374 smooth, rectangular approach channel extend upstream of the weir for a distance not les! than
41、twice the maximum head. Irrigatioi c) V-shaped IS0 8333 80 Oh channels with little fall available and wide range of flow. Triangular-profile weirs IS04360 2to5 75 Ya 3,5 3) Hydrometric networks and principal irrigatior channels Streamlined triangular- IS0 9827 2 to 5 ? ? Irrigation work and minor ch
42、annels profile weirs Flat-V weirs IS0 4377 2 to 5 70 % 2,5 3) Hydrometric works with wide range of flow Compound gauging IS0 14139 2 to 5 Varies Vary Hydrometrk works with wide range of flow structures Trapezoidal-profile weirs IS0 4362 4 to 8 65 Yoto 1,33) Where ease of construction is an importan
43、Vertical underflow gates IS0 13550 4 to 8 2) See Situations where a near constant upstrean and radial gates IS0 13550 water level is required. End-depth method 2) 6) Where accuracy may be relaxed for simplicit! a) rectangular IS03847 5t010 b) non-rectangular IS0 4371 Long-throated flumes IS0 4359 2
44、to 5 74 % 0,7 5) Flumes can be used in channels of any shape if flow conditions in the approach channel art reasonably uniform and steady. Sediment laden channels, flow with debris, flow wit! migratory fish, conduits and partially fillec pipes, flow in sewers. Patshall and SANIIRI IS0 9826 4 to 8 60
45、 %to See Flumes can be used in channels of any shape flumes 80 % is0 9826 if flow conditions in the approach channel are reasonably uniform and steady. Hydrometric networks and water distribution channels. 1) The modular limit of each device requires careful consideration. The submergence ratio shou
46、ld be checked for the whole range of flows ta be measured and compared with values for the modular limit given in Table 1. crest I5 3903) 85 %4) factor. Irrigation works and minor channels. and economy. BS IS0 8368:1999 uncer- national tainties in Modular) Standard computed limit discharge, Inter- T
47、YP Table 1 - Applications and limitations of structures Limitations Typical application 2) Nappe to be fully aerated. 3) Maximum Wp, where His the total upstream head and p is the height of the weir. 4) Depends on geometry. 5) Maximum A,/ p: height of weir; b: breadth of weir or flume throat; rn: side slopes: 1 vertical; rn horizontal; L: length of flume throat or weir crest. BS IS0 8368:1999 Table 2 - Comparative discharges for various weirs and flumes 5
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