BS ISO 4377:2002
$167.15
Hydrometric determinations. Flow measurement in open channels using structures. Flat-V weirs
| Published By | Publication Date | Number of Pages |
| BSI | 2002 | 42 |
PDF Catalog
| PDF Pages | PDF Title |
|---|---|
| 3 | TitlePage – Hydrometric determinations�— Flow measurement in open channels using structures�— Fla… |
| 5 | TableofContent – Contents Page |
| 6 | Foreword – Foreword |
| 7 | Scope – 1��� Scope NormativeReference – 2��� Normative references |
| 9 | Clause1 – 4��� Symbols |
| 10 | Clause1 – 5��� Characteristics of flat-V weirs Clause1 – 6��� Installation Subclause2 – 6.1��� Selection of site UntitledSubclause3 – 6.1.1��� The weir shall be located in a straight section of the channel, avo… UntitledSubclause3 – 6.1.2��� A preliminary study of the physical and hydraulic features of the p… |
| 11 | UntitledSubclause3 – 6.1.3��� If the site does not possess the characteristics necessary for sati… |
| 12 | Subclause2 – 6.2��� Installation conditions Subclause3 – 6.2.1��� General requirements Subclause3 – 6.2.2��� Approach channel UntitledSubclause4 – 6.2.2.1��� If the flow in the approach channel is disturbed by irregularitie… UntitledSubclause4 – 6.2.2.2��� A minimum required length of straight approach channel shall be f… UntitledSubclause4 – 6.2.2.3��� In a natural channel where it is uneconomic to line the bed and b… UntitledSubclause4 – 6.2.2.4��� Vertical side walls constructed to effect a narrowing of the natu… UntitledSubclause4 – 6.2.2.5��� In a channel where the flow is free from floating and suspended d… UntitledSubclause4 – 6.2.2.6��� Under certain conditions, a hydraulic jump may occur upstream of … UntitledSubclause4 – 6.2.2.7��� Conditions in the approach channel can be verified by inspection … |
| 13 | Subclause2 – 6.3��� Weir structure UntitledSubclause3 – 6.3.1��� The structure shall be rigid and watertight and capable of withstan… UntitledSubclause3 – 6.3.2��� The weir and the approach channel as far as the upstream tapping po… UntitledSubclause3 – 6.3.3��� In order to minimize uncertainty in the discharge, the following to… UntitledSubclause3 – 6.3.4��� The structure shall be measured upon completion and mean dimensiona… Subclause2 – 6.4��� Downstream conditions Clause1 – 7��� Maintenance |
| 14 | Clause1 – 8��� Measurement of head(s) Subclause2 – 8.1��� General Subclause2 – 8.2��� Gauge wells UntitledSubclause3 – 8.2.1��� It is common practice to measure the upstream head in a gauge well … UntitledSubclause3 – 8.2.2��� Gauge wells shall be vertical and of sufficient height and depth to… UntitledSubclause3 – 8.2.3��� Both the well and the connecting pipe shall be watertight. Where th… UntitledSubclause3 – 8.2.4��� The invert of the pipe shall be positioned at a distance of no less… UntitledSubclause3 – 8.2.5��� Pipe connections to the upstream and downstream head measurement po… UntitledSubclause3 – 8.2.6��� The static head at the separation pocket behind the crest of the we… |
| 15 | UntitledSubclause3 – 8.2.7��� Adequate additional depth shall be provided in wells to avoid the d… UntitledSubclause3 – 8.2.8��� The diameter of the connecting pipe or width of slot to the upstrea… Subclause2 – 8.3��� Zero setting UntitledSubclause3 – 8.3.1��� Accurate initial setting of the zeros of the head measuring devices… UntitledSubclause3 – 8.3.2��� An accurate means of checking the zero at frequent intervals shall … UntitledSubclause3 – 8.3.3��� A zero check based on the water level (either when the flow ceases … |
| 17 | UntitledSubclause3 – 8.3.4��� Values for the crest cross-slope, Subclause2 – 8.4��� Location of head measurement sections UntitledSubclause3 – 8.4.1��� The approach flow to a flat-V weir is three dimensional. Drawdown i… UntitledSubclause3 – 8.4.2��� If other considerations necessitate siting the tapping closer to th… UntitledSubclause3 – 8.4.3��� Flat-V weirs can be used for gauging purposes in the drowned flow r… |
| 18 | UntitledSubclause3 – 8.4.4��� Alternatively flat-V weirs can be used for gauging purposes in the … Clause1 – 9��� Discharge relationships Subclause2 – 9.1��� Equations of discharge UntitledSubclause3 – 9.1.1��� In terms of total head, the basic discharge equation for a flat-V w… |
| 19 | UntitledSubclause3 – 9.1.2��� In terms of total head, the basic discharge equation for a flat-V w… |
| 20 | Subclause2 – 9.2��� Effective heads Subclause2 – 9.3��� Shape factors Subclause2 – 9.4��� Coefficient of velocity UntitledSubclause3 – 9.4.1��� The coefficient of velocity, UntitledSubclause3 – 9.4.2��� The coefficient of velocity, |
| 21 | Subclause2 – 9.5��� Conditions for modular/drowned flow |
| 24 | Subclause2 – 9.6��� Drowned flow reduction factor UntitledSubclause3 – 9.6.1��� The drowned flow reduction factor, UntitledSubclause3 – 9.6.2��� In UntitledSubclause3 – 9.6.3��� In the absence of crest tappings, downstream tappings may be used t… |
| 31 | Subclause2 – 9.7��� Limits of application UntitledSubclause3 – 9.7.1��� The practical lower limit of upstream head is related to the magnit… UntitledSubclause3 – 9.7.2��� There is also a limiting value for the ratio UntitledSubclause3 – 9.7.3��� There is a limiting Froude number for the flow conditions in the ap… Clause1 – 10��� Computation of discharge Subclause2 – 10.1��� General Subclause2 – 10.2��� Successive approximation method Subclause3 – 10.2.1��� Computation using individual head measurements |
| 32 | Subclause3 – 10.2.2��� Computation of modular stage-discharge function |
| 33 | Subclause2 – 10.3��� Coefficient of velocity method Subclause3 – 10.3.1��� Modular flow conditions Subclause3 – 10.3.2��� Drowned flow conditions Subclause2 – 10.4��� Accuracy UntitledSubclause3 – 10.4.1��� The overall accuracy of measurement will depend on the following: UntitledSubclause3 – 10.4.2��� The uncertainties ( |
| 34 | Clause1 – 11��� Uncertainties in flow measurement Subclause2 – 11.1��� General UntitledSubclause3 – 11.1.1��� The uncertainty of any flow measurement can be estimated if the un… UntitledSubclause3 – 11.1.2��� The error in a result is the difference between the true rate of f… UntitledSubclause3 – 11.1.3��� As far as is practicable this clause is in accordance with Subclause2 – 11.2��� Sources of error |
| 35 | Subclause2 – 11.3��� Types of error UntitledSubclause3 – 11.3.1��� Errors can be classified as random or systematic, the former affec… UntitledSubclause3 – 11.3.2��� A measurement can also be subject to systematic error; the mean of… |
| 36 | Subclause2 – 11.4��� Errors in quantities given in this standard UntitledSubclause3 – 11.4.1��� All the errors in this category are systematic. The values of the … UntitledSubclause3 – 11.4.2��� However, when measurements are made on other similar installations… UntitledSubclause3 – 11.4.3��� The probable uncertainties in the coefficients and the corrective … Subclause2 – 11.5��� Errors in quantities measured by the user UntitledSubclause3 – 11.5.1��� Both random and systematic errors occur in user measurements. UntitledSubclause3 – 11.5.2��� Since neither the methods of measurement nor the way in which they… UntitledSubclause3 – 11.5.3��� The uncertainty in the gauged head is determined from an assessmen… UntitledSubclause3 – 11.5.4��� The above component uncertainties shall be calculated as percentag… Subclause2 – 11.6��� Combination of uncertainty to give the overall uncertainty in discharge UntitledSubclause3 – 11.6.1��� The uncertainty in discharge is given by the expression: UntitledSubclause3 – 11.6.2��� The uncertainty in discharge is not a single value for a given dev… Clause1 – 12��� Examples Subclause2 – 12.1��� Modular flow at low discharge ( Subclause3 – 12.1.1��� Data |
| 37 | Subclause3 – 12.1.2��� Solution by successive approximation method |
| 38 | Subclause3 – 12.1.3��� Solution by coefficient of velocity method Subclause3 – 12.1.4��� Uncertainty in computed discharge Subclause2 – 12.2��� Drowned flow at high discharge Subclause3 – 12.2.1��� Data |
| 39 | Subclause3 – 12.2.2��� Solution using successive approximation method |
| 40 | Subclause3 – 12.2.3��� Solution using the coefficient of velocity method Subclause3 – 12.2.4��� Uncertainty in computed discharge |
| 41 | AnnexNormative – Velocity distribution UntitledClause1 – A.1��� An even distribution of velocity over the cross-section of the approach … UntitledClause1 – A.2��� Normal velocity distribution is defined as “the distribution of velociti… UntitledClause1 – A.3��� Any deviation from the ideal conditions of either uniform or a normal ve… UntitledClause1 – A.4��� In UntitledClause1 – A.5��� The percentage difference in the value of |
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