Booklet 7 - Flow Measurement Methods in Open Channels

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TABLE 7 - PARSHALL FLUME - DISCHARGE EQUATIONS IN FREE FLOW CONDITIONSFlumedimensionsDISCHARGE EQUATIONW m 3 /s (**) m 3 /d (**) ft 3 /s (*) Mgal US /d (*)1" 0.0604 H 1.55 5 215 H 1.55 0.338 H 1.55 0.2185H 1.552" 0.1207 H 1.55 10 430 H 1.55 0.676 H 1.55 0.4369H 1.553" 0.1765 H 1.547 15 250 H 1.547 0.992 H 1.547 0.6412H 1.5476" 0.3812 H 1.58 32 937 H 1.58 2.060 H 1.58 1.3314H 1.589" 0.5354 H 1.53 46 258 H 1.53 3.070 H 1.53 1.9842H 1.531' 0.6909 H 1.522 59 696 H 1.522 4.0 H 1.522 2.5853H 1.52218" 1.0563 H 1.538 91 263 H 1.538 6.0 H 1.538 3.8779H 1.5382' 1.4286 H 1.550 123 432 H 1.550 8.0 H 1.550 5.1706H 1.5503' 2.184 H 1.566 188 701 H 1.566 12.0 H 1.566 7.7559H 1.5664' 2.9539 H 1.578 255 214 H 1.578 16.0 H 1.578 10.341H 1.5785' 3.732 H 1.587 322 448 H 1.587 20.0 H 1.587 12.926H 1.5876' 4.5212 H 1.595 390 632 H 1.595 24.0 H 1.595 15.512H 1.5958' 6.1148 H 1.607 528 322 H 1.607 32.0 H 1.607 20.682H 1.60710' 7.4628 H 1.6 644 782 H 1.6 39.38 H 1.6 25.452H 1.612' 8.8594 H 1.6 756 453 H 1.6 46.75 H 1.6 30.216H 1.615' 10.955 H 1.6 946 542 H 1.6 57.81 H 1.6 37.364H 1.620' 14.45 H 1.6 1 248 466 H 1.6 76.25 H 1.6 49.282H 1.625' 17.944 H 1.6 1 550 391 H 1.6 94.69 H 1.6 61.20H 1.630' 21.439 H 1.6 1 852 315 H 1.6 113.13 H 1.6 73.118H 1.640' 28.426 H 1.6 2 456 000 H 1.6 150 H 1.6 96.948H 1.650' 35.415 H 1.6 3 059 848 H 1.6 186.88 H 1.6 120.785H 1.6(*) H expressed in feet(**) H expressed in metersPage 42 of 223Booklet 7 - Flow Measurement Methods in Open Channels
2.1.7. PrecisionThe margin for error with a Parshall flume is approximately ± 3 %. To generate this degree of precision, it isimportant to carefully comply with all of the recommended dimensions when a flume is manufactured andinstalled.2.1.8. Sources of errorThe principal sources of error that reduce a flume’s precision are as follows:−changes to standard dimensions that occur when a flume is manufactured or during its installationdistortion: check all sections of the flume to ensure that it has not been compressed or twistedduring installation.throat width: for small flumes, a tolerance of 4 mm (1/64 in) compared to a standarddimension, is acceptable. For larger flumes, a deviation of 8 mm (1/32 in) is acceptable, (seeTable 5).length of converging section: this section cannot be reduced, but there appears to be norestriction to extend it. The measuring point, however, must remain in a standard position.horizontal position: if the base of the flume is not level transversely, the average depth must beused to determine the depth/flow relationship, in other words, the depth must be measured oneach side of the flume to determine the average depth.−incorrect measuring point positionfor all sizes of flumes, the measuring point must be located within the 2/3 portion of theconverging section, the distance of which must be measured along the wall, from the beginningof the throat.A2/3 ABooklet 7 - Flow Measurement Methods in Open Channels Page 43 of 223
Page 1: Centre d’expertise en analyse env
Page 5: FOREWORDThis Sampling Guide for Env
Page 8 and 9: 4.4. Area/velocity method..........
Page 10 and 11: LIST OF ILLUSTRATIONSFigure 1 - Wei
Page 13 and 14: 1. GENERAL1.1. Definition of flowra
Page 15 and 16: Note: If effluents have different d
Page 17 and 18: This equation shows that water dept
Page 19 and 20: Sizes vary according to the type an
Page 21 and 22: FIGURE 1 - WEIR COMPONENTSFlow is d
Page 23 and 24: 1.10. Reference measurementIf a mea
Page 25 and 26: FIGURE 2 - PALMER-BOWLUS - FLUME CH
Page 27 and 28: TABLE 1 - DIMENSIONS FOR PALMER-BOW
Page 29 and 30: 1.12. Choosing a measurement method
Page 31 and 32: FIGURE 4 - FLUME - FLUME AND FLOW C
Page 33 and 34: TABLE 3 - CHART FOR COMPARING THE M
Page 35 and 36: TABLE 4 - DIMENSIONS FOR STILLING W
Page 37 and 38: 2. DESCRIPTION OF FLUMESThe section
Page 39 and 40: 2.1.2. Operating principleA Parshal
Page 41 and 42: TABLE 5 - PARSHALL FLUME - STANDARD
Page 43: TABLE 6 - PARSHALL FLUME - RECOMMEN
Page 47 and 48: channel at maximum flow (H c ), bef
Page 49 and 50: FIGURE 8 - PARSHALL FLUME - JUNCTIO
Page 51 and 52: FIGURE 9 - PARSHALL FLUME - EFFECTS
Page 53 and 54: 2.1.12. Discharge equation in a sub
Page 55 and 56: FIGURE 11 - LOSS OF HEAD - PARSHALL
Page 57 and 58: To monitor the total rise, follow t
Page 59 and 60: A Palmer-Bowlus flume, as experimen
Page 61 and 62: FIGURE 13 - SHAPE OF A PALMER-BOWLU
Page 63 and 64: TABLE 10 - PALMER-BOWLUS FLUME - ST
Page 65 and 66: Because some manufacturers do not a
Page 67 and 68: −use of the depth/flow table2.2.1
Page 69 and 70: For temporary systems, a simple ver
Page 71 and 72: Q is the flowrate in liters or US g
Page 73 and 74: FIGURE 15 - SHAPE OF LEOPOLD-LAGCO
Page 75 and 76: 2.3.7. Measurement capacity of a fl
Page 77 and 78: 2.3.11. Installation specifications
Page 79 and 80: 2.4.2. Operating principleCutthroat
Page 81 and 82: TABLE 14 - CUTTHROAT FLUME - STANDA
Page 83 and 84: TABLE 15 - CUTTHROAT FLUME - RECOMM
Page 85 and 86: TABLE 16 - CUTTHROAT FLUME - VALUES
Page 87 and 88: TABLE 18 - CUTTHROAT FLUME - DISCHA
Page 89 and 90: Since a number of other cutthroat f
Page 91 and 92: where:Q is the flowrate in cubic me
Page 93 and 94: Example: To measure a 0.6 m 3 (21 C
Page 95 and 96:
It consists of two sections: approa
Page 97 and 98:
FIGURE 18 - H FLUME - PHYSICAL CHAR
Page 99 and 100:
Although this type of flume can be
Page 101 and 102:
TABLE 21 - H FLUME - STANDARD DIMEN
Page 103 and 104:
TABLE 23 - H FLUME - RECOMMENDED MI
Page 105 and 106:
CoefficientsandexponentsTABLE 24 -
Page 107 and 108:
−erosion at the outlet of the flu
Page 109 and 110:
2.5.13. Flume modificationTo obtain
Page 111 and 112:
Example:For a rectangular weir wher
Page 113 and 114:
−−−−−−−the presence o
Page 115 and 116:
TABLE 25 - WEIR CALIBRATION - VOLUM
Page 117 and 118:
FIGURE 20 - RECTANGULAR WEIR WITHOU
Page 119 and 120:
TABLE 26 - RECTANGULAR WEIR WITHOUT
Page 121 and 122:
Inadequate approach velocityThe app
Page 123 and 124:
FIGURE 21 - RECTANGULAR WEIR WITH C
Page 125 and 126:
The Kindsvater-Carter equation take
Page 127 and 128:
3.3.5. PrecisionIn free flow condit
Page 129 and 130:
TABLE 28 - RECTANGULAR WEIR WITH CO
Page 131 and 132:
FIGURE 22 - TRAPEZOIDAL WEIR (CIPOL
Page 133 and 134:
TABLE 29 - TRAPEZOIDAL WEIR (CIPOLL
Page 135 and 136:
Length of contractionsIf side contr
Page 137 and 138:
In addition to the information prov
Page 139 and 140:
The discharge equation resulting fr
Page 141 and 142:
3.6. Combined weirTo obtain a preci
Page 143 and 144:
In addition to the information prov
Page 145 and 146:
3.6.5. PrecisionIn free flow condit
Page 147 and 148:
FIGURE 25 -COMPOUND WEIR - PHYSICAL
Page 149 and 150:
TABLE 32 - COMPOUND WEIR - MEASUREM
Page 151 and 152:
4.1.1.2 Characteristics of tracersT
Page 153 and 154:
S gis the specific weight of the tr
Page 155 and 156:
4.1.2.1.4 Disadvantages of the meth
Page 157 and 158:
When selecting a sampling point, it
Page 159 and 160:
4.1.2.2.8 Detection and measurement
Page 161 and 162:
Dyes are well suited to flow measur
Page 163 and 164:
4.1.2.3.8 Detection and measurement
Page 165 and 166:
4.1.2.4.3 Preparation of radioactiv
Page 167 and 168:
4.1.2.4.9 Preliminary testsBefore c
Page 169 and 170:
4.1.3.1.3 Advantages of the method
Page 171 and 172:
Testing procedures are as follows:T
Page 173 and 174:
Use the following formula to determ
Page 175 and 176:
The discharge equation is therefore
Page 177 and 178:
• Choosing a tracerExamine the di
Page 179 and 180:
Sampling must be carried out during
Page 181 and 182:
−−contamination of sampling con
Page 183 and 184:
Instantaneous injections1 2 3 4 5nP
Page 185 and 186:
tracer is lost due to splashing, by
Page 187 and 188:
The concentration of tracers is usu
Page 189 and 190:
4.1.3.3.7 Causes of errorThe princi
Page 191 and 192:
4.2.4. DisadvantagesThe principal d
Page 193 and 194:
−If the dimensions cannot be meas
Page 195 and 196:
4.3.7. DisadvantagesFlow measuremen
Page 197 and 198:
4.3.8.2 Calculation of pumping time
Page 199 and 200:
4.3.8.4 Number of testsWhen a pumpi
Page 201 and 202:
−−−−−requires a number of
Page 203 and 204:
4.4.9. Flow areaMeasurement of the
Page 205 and 206:
Velocity measurements should be tak
Page 207 and 208:
considering only the source of erro
Page 209 and 210:
There are also other causes of bias
Page 211 and 212:
12. GRANT, D. M., ISCO Open Channel
Page 213:
36. INTERNATIONAL STANDARD ORGANISA
Page 216 and 217:
CHANDRA, U., Aoki, P. E., Ramos e S
Page 218 and 219:
HAMMER, Mark J., Water and Waste-Wa
Page 220 and 221:
Resources Instrumentation, June 4-6
Page 222 and 223:
REPLOGLE, John A., Meyers, Lloyd E.
Page 224 and 225:
TRIESTE, Douglas J., Evaluation of
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Booklet 7 - Flow Measurement Methods in Open Channels

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