Booklet 7 - Flow Measurement Methods in Open Channels

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Dimensions in millimeters and inches (or feet)TABLE 2 - DIMENSIONS FOR PARSHALL FLUME CHAMBERW L D M B E F G S P P1 T T1251 "512 "763 "1526 "2299 "30512 "45718 "61024 "9143’12194’15245’18296’21347’24388’304810’365812’457215’609620’762525’914430’1219240’1524050’30512 "45718 "61024 "91436 "137254 "18296’24388’24388’304810’365812’457215’457215’487716’548618’640121’731524’914430’1158238’1371645’1463048’1645954’1889862’1686 19/32 "2148 13/32 "25910 3/16 "3971' 3 5/8"5751' 10 5/8"8452' 9 1/4"10263' 4 3/8"12073' 11 1/2"15725' 1 7/8"16326' 4 1/4"19977' 6 5/8"26678' 9"30329' 11 3/8"339711' 1 3/4"475615' 7 1/4"560718' 4 3/4"762525'914430'1066835'1231240' 4 3/4"1548150' 9 1/2"1852960' 9 1/2"--- 3561'2"--- 4061'4"--- 4571'6"305 6101' 2'305 8641' 2'10"381 13431'3" 4' 4 7/8"381 14191'3" 4' 7 7/8"381 14951'3" 4' 10 7/8"381 16451'3" 5' 4 3/4"457 17941'6" 5' 10 5/8"457 19431'6" 6' 4 1/2"457 20921'6" 6' 10 3/8"457 22421'6" 7' 4 1/4"457 23911'6" 7' 10 1/8"--- 426714'--- 487716'--- 762525'--- 762525'--- 762525'--- 792526'--- 823027'--- 823027'2299"30512"61024"61024"76230"9143'9143'9143'9143'9143'9143'9143'9143'9143'12194'15245'18296'21347'21347'21347'21347'21347'763"1144 1/2"1526"3051'3051'6102'6102'6102'6102'6102'6102'6102'6102'6102'9143'9143'12194'18296'18296'18296'18296'18296'2038"25410"3051'6102'4571' 6"9143'9143'9143'9143'9143'9143'9143'9143'9143'18296'24388'304810'365812'396213'426714'487716'609620'30512"45718"61024"61024"76230"91436"106742"106742"12194'15245'15245'18296'18296'21347'21347'24388'24388'27699'27699'304810'304810'335311'1686 19/32"91436"214 9148 13/32" 36"259 91410 3/16" 36"902 9142' 11 1/2" 36"1080 12193' 6 1/2" 4'1492 15244' 10 3/4 5'1676 18295' 6" 6'1854 21346' 1" 7'2223 24387' 3 1/2" 8'2712 27698' 10 3/4" 9'3080 335310' 1 1/4" 11'3442 365711' 3 1/2" 12'3810 396212' 6" 13'4172 426713' 8 1/4" 14'--- 487716'--- 609620'--- 762525'--- 914430'--- 1066835'--- 1280242'--- 1585052'--- 1889862'2489 3/4"32712 7/8"63525"68627"83833"9913' 3"9913' 3"9913' 3"9913' 3"9913' 3"9913' 3"9913' 3"9913' 3"9913' 3"13724' 6"16765' 6"20576' 9"24388'24388'24388'24388'24388'25710 1/8"34813 11/16"66726 1/4"72428 1/2"87634 1/2"114345 "114345 "114345"114345 "114345 "114345 "114345 "114345 "114345 "15625' 1 1/2"18676' 1 1/2"22867' 6"28199' 3"28199' 3"28199' 3"28199' 3"28199' 3"Page 26 of 223Booklet 7 - Flow Measurement Methods in Open Channels
1.12. Choosing a measurement method1.12.1. Selection criteriaIt is important to select the right method to produce an accurate effluent flow measurement. The variety ofmethods available makes choosing the right one difficult. To guide you in determining which method is best,needs must be defined, the methods available must be gauged and possible compromises examined.The following criteria must be considered (3) :− the presence of solids in water;− the desired precision and possible precision of each method;− the maximum flow to measure (Q max );− range of measurements (Q max /Q min );− tolerance to fluctuations in discharge;− width of the flume;− the allowable and resulting maximum drop in pressure for each method;− the repeatability and reliability required;− the need to connect the measuring instrument to a data entry and processing system;− the acceptable precision produced by the measuring instrument in use;− sensitivity of the instrument to fluctuations in flow;− installation and maintenance costs.1.12.2. Presence of solidsEffluents contain all types of suspended solids of varying shapes and sizes. Solids tend to deposit upstreamfrom the measuring device, stick to walls, become entangled in equipment and adhere to structures.Upstream deposits can obstruct flow or change approach velocities, and deposits that adhere to the walls of ameasuring device can distort geometry and its original dimensions. Readings using such equipment can beinaccurate. This is particularly true in the case of weirs.Some primary measurement devices are affected little by the presence of suspended solids, particularly flumes,because they have smooth walls and a relatively flat bottom.1.12.3. Maximum flowBefore selecting a particular measurement method, it is important to inspect the size of flow that may bemeasured. This information can be obtained in a several ways:−−−−a thorough knowledge of the facility (process, use of water, sewer network, etc.);a measurement of water consumption;the relationship between water consumption and manufacturing rates for a similar facility;the water supply capacity;Booklet 7 - Flow Measurement Methods in Open Channels Page 27 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: TABLE 1 - DIMENSIONS FOR PALMER-BOW
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 and 44: TABLE 6 - PARSHALL FLUME - RECOMMEN
Page 45 and 46: 2.1.7. PrecisionThe margin for erro
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
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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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