ENGINEERING TOMORROW
sheet
AB-QM f low checker DN 40 -250
Verifying the f low on DN 40
to DN 250 AB-QM valves
AB-QM 3TP Flow Checker
Flow verification in an installation
To verify that an installation functions according to the design specifications checking only the most critical valve in the installation is needed (see figure 1).
The AB-QM maintains a constant differential pressure over the valve and any excess pressure will automatically be throt tled. If there is not enough differential pressure the valve cannot reach the set flow.
The valve that is furthest away from the pump or the valve in the circuit with the highest resistance has the lowest available differential pressure, so if this critical valve has enough pressure it means the other valves will also function properly.
Important :
To get a useful measurement the installation should run on full load, so all actuators in the installation should be opened fully. This ensures that you are measuring under the most unfavorable circumstances. The AB-QM’s will have more differential pressure available when the installation is working on partial load.
Method of verification
Measure the differential pressure across the control valve.
The measuring nipples are placed in such a way that p1−p2 is measured (see figure 2).
Therefore the measured differential pressure can be used to calculate the flow directly. It ’s necessary to use the table that was derived fromstatistical measurements Since the measurements across the measuring points are influenced by the dynamic pressure, turbulences, flow pat terns, internal tolerances, set ting accuracy and accuracy of the measuring equipment we believe that the total accuracy of the measurement is lower than performance of the valve.
Therefore we recommend not to adjust the set ting when the results are within 10 % of the expected flow.
Calculat ing the flow
Pcv=p1-p2
For kv Cv values see tables in figure 4 and 7
| Presetting | DN 40 | DN 50 / DN 50HF | DN 65 / DN 65HF | DN 80 / DN 80HF | DN 100 / DN 100HF |
| s % | kvCv (m3/ h) | ||||
| 20.0 % | 3.40 | 4.60 | 4.20 | 15.50 | 19.50 |
| 22.5 % | 4.08 | 5.55 | 5.48 | 17.19 | 21.94 |
| 25.0 % | 4.80 | 6.50 | 6.75 | 18.88 | 24.38 |
| 27.5 % | 5.43 | 7.45 | 8.03 | 20.56 | 26.81 |
| 30.0 % | 6.10 | 8.40 | 9.30 | 22.25 | 29.25 |
| 32.5 % | 6.78 | 9.35 | 10.58 | 23.94 | 31.69 |
| 35.0 % | 7.50 | 10.30 | 11.85 | 25.63 | 34.13 |
| 37.5 % | 8.13 | 11.25 | 13.13 | 27.31 | 36.56 |
| 40.0 % | 8.80 | 12.20 | 14.40 | 29.00 | 39.00 |
| 42.5 % | 9.48 | 13.15 | 15.68 | 30.69 | 41.44 |
| 45.0 % | 10.20 | 14.10 | 16.95 | 32.38 | 43.88 |
| 47.5 % | 10.83 | 15.05 | 18.23 | 34.06 | 46.31 |
| 50.0 % | 11.50 | 16.00 | 19.50 | 35.75 | 48.75 |
| 52.5 % | 12.18 | 16.95 | 20.78 | 37.44 | 51.19 |
| 55.0 % | 12.90 | 17.90 | 22.05 | 39.13 | 53.63 |
| 57.5 % | 13.53 | 18.85 | 23.33 | 40.81 | 56.06 |
| 60.0 % | 14.20 | 19.80 | 24.60 | 42.50 | 58.50 |
| 62.5 % | 14.88 | 20.75 | 25.88 | 44.19 | 60.94 |
| 65.0 % | 15.55 | 21.70 | 27.15 | 45.88 | 63.38 |
| 67.5 % | 16.26 | 22.65 | 28.43 | 47.56 | 65.81 |
| 70.0 % | 16.90 | 23.60 | 29.70 | 49.25 | 68.25 |
| 72.5 % | 17.58 | 24.55 | 30.98 | 50.94 | 71.81 |
| 75.0 % | 18.25 | 25.50 | 32.25 | 52.63 | 75.38 |
| 77.5 % | 18.93 | 26.45 | 33.53 | 54.31 | 78.94 |
| 80.0 % | 19.60 | 27.40 | 34.80 | 56.00 | 82.50 |
| 82.5 % | 20.28 | 28.35 | 36.08 | 57.69 | 86.06 |
| 85.0 % | 20.95 | 29.30 | 37.35 | 59.38 | 89.63 |
| 87.5 % | 21.63 | 30.25 | 38.63 | 61.06 | 93.19 |
| 90.0 % | 22.30 | 31.20 | 39.90 | 62.75 | 96.75 |
| 92.5 % | 22.98 | 32.15 | 41.18 | 64.44 | 100.31 |
| 95.0 % | 23.65 | 33.10 | 42.45 | 66.13 | 103.88 |
| 97.5 % | 24.33 | 34.05 | 43.73 | 67.81 | 107.44 |
| 100.0 % | 25.00 | 35.00 | 45.00 | 69.50 | 111.00 |
Fig. 4 The flow is according to setting if the calculated flow is in the range of ±10 % of the set flow.
| Presetting | DN 125 / DN 125HF | DN 150 / DN 150HF | DN 200 / DN 200HF | DN 250 / DN 250HF |
| s % | kvCv (m3/ h) | |||
| 20.0 % | 40 | 53 | 57 | 86 |
| 22.5 % | 45 | 60 | 66 | 99 |
| 25.0 % | 49 | 67 | 75 | 112 |
| 27.5 % | 53 | 74 | 85 | 125 |
| 30.0 % | 57 | 81 | 94 | 138 |
| 32.5 % | 61 | 88 | 104 | 150 |
| 35.0 % | 65 | 95 | 113 | 163 |
| 37.5 % | 69 | 101 | 122 | 176 |
| 40.0 % | 73 | 108 | 132 | 189 |
| 42.5 % | 77 | 115 | 141 | 202 |
| 45.0 % | 82 | 122 | 151 | 215 |
| 47.5 % | 86 | 129 | 160 | 227 |
| 50.0 % | 90 | 136 | 170 | 240 |
| 52.5 % | 94 | 143 | 179 | 253 |
| 55.0 % | 98 | 150 | 188 | 266 |
| 57.5 % | 102 | 157 | 198 | 279 |
| 60.0 % | 106 | 163 | 207 | 292 |
| 62.5 % | 110 | 170 | 217 | 304 |
| 65.0 % | 114 | 177 | 226 | 317 |
| 67.5 % | 119 | 184 | 235 | 330 |
| 70.0 % | 123 | 191 | 245 | 343 |
| 72.5 % | 127 | 198 | 254 | 356 |
| 75.0 % | 131 | 205 | 264 | 369 |
| 77.5 % | 135 | 212 | 273 | 381 |
| 80.0 % | 139 | 219 | 283 | 394 |
| 82.5 % | 143 | 225 | 292 | 407 |
| 85.0 % | 147 | 232 | 301 | 420 |
| 87.5 % | 152 | 239 | 311 | 433 |
| 90.0 % | 156 | 246 | 320 | 446 |
| 92.5 % | 160 | 253 | 330 | 458 |
| 95.0 % | 164 | 260 | 339 | 471 |
| 97.5 % | 168 | 267 | 348 | 484 |
| 100.0 % | 172 | 274 | 358 | 497 |
| 102.5% | 176 | 281 | 367 | 510 |
| 105.0% | 180 | 287 | 377 | 523 |
| 107.5% | 184 | 294 | 386 | 535 |
| 110.0% | 189 | 301 | 396 | 548 |
Fig. 7 The flow is according to setting if the calculated flow is in the range of ±10% of the set flow.
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Documents / Resources
 |
Danfoss AB-QM 3TP Flow Checker [pdf] Installation Guide 3TP, DN 40-250, AB-QM 3TP Flow Checker, AB-QM 3TP, Flow Checker, Checker |