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Ventilation Ducts - Minor Loss Resistance

Minor pressure or head loss in ventilation ducts vs. air velocity - minor loss coefficient diagram.

Minor pressure loss - Pa or N/m2 - in air ducts can be estimated by using the diagram or table below:

minor loss diagram air ductwork

Ventilation Ducts - Minor Loss Resistance
Flow Velocity
(m/s)		Minor Loss (Pa, N/m2)
Minor Loss Resistance Coefficient - ξ
12345678910
2 2.4 4.8 7.3 9.7 12.1 14.5 16.9 19.4 21.8 24.2
2.5 3.8 7.6 11.3 15.1 18.9 22.7 26.5 30.3 34.0 37.8
3 5.4 10.9 16.3 21.8 27.2 32.7 38.1 43.6 49.0 54.5
3.5 7.4 14.8 22.2 29.6 37.1 44.5 51.9 59.3 66.7 74.1
4 9.7 19.4 29.0 38.7 48.4 58.1 67.8 77.4 87.1 96.8
4.5 12.3 24.5 36.8 49.0 61.3 73.5 85.8 98.0 110 122
5 15.1 30.3 45.4 60.5 75.6 90.8 105 121 136 151
5.5 18.3 36.6 54.9 73.2 91.5 109 128 146 164 183
6 21.8 43.6 65.3 87.1 108 130 152 174 196 217
6.5 25.6 51.1 76.7 102 127 153 178 204 230 255
7 29.6 59.3 88.9 118 148 177 207 237 266 296
7.5 34.0 68.1 102 136 170 204 238 272 306 340
8 38.7 77.4 116 154 193 232 271 309 348 387
8.5 43.7 87.4 131 174 218 262 306 349 393 437
9 49.0 98.0 147 196 245 294 343 392 441 490
9.5 54.6 109 163 218 273 327 382 436 491 546
10 60.5 121 181 242 302 363 423 484 544 605
10.5 66.7 133 200 266 333 400 466 533 600 667
11 73.2 146 219 292 366 439 512 585 658 732
11.5 80.0 160 240 320 400 480 560 640 720 800
12 87.1 174 261 348 435 522 609 697 784 871
12.5 94.5 189 283 378 472 567 661 756 850 945
13 102 205 306 409 511 613 715 818 920 1022
13.5 110 221 330 441 551 661 771 882 992 1102
14 119 237 355 474 592 711 830 948 1067 1185
14.5 127 254 381 508 636 763 890 1017 1144 1272
15 136 272 408 544 680 816 952 1089 1225 1361
15.5 145 290 436 581 726 872 1017 1162 1308 1453
16 155 309 464 619 774 929 1084 1239 1393 1548
16.5 165 329 494 658 823 988 1153 1317 1482 1647
17 175 349 524 699 874 1049 1223 1398 1573 1748
17.5 185 370 555 741 926 1111 1297 1482 1667 1852
18 196 392 588 784 980 1176 1372 1568 1764 1960
18.5 207 414 621 828 1035 1242 1449 1656 1863 2070
19 218 436 655 873 1092 1310 1528 1747 1965 2184
19.5 230 460 690 920 1150 1380 1610 1840 2070 2300
20 242 484 726 968 1210 1452 1694 1936 2178 2420
20.5 254 508 762 1017 1271 1525 1779 2034 2288 2542
21 267 533 800 1067 1334 1600 1867 2134 2401 2668
21.5 280 559 839 1118 1398 1678 1957 2237 2517 2796
22 293 585 878 1171 1464 1756 2049 2342 2635 2928
22.5 306 612 918 1225 1531 1837 2144 2450 2756 3062
23 320 640 960 1280 1600 1920 2240 2560 2880 3200
23.5 334 668 1002 1336 1670 2004 2338 2672 3007 3341
24 349 697 1045 1393 1742 2090 2439 2787 3136 3484
24.5 363 726 1089 1452 1815 2178 2542 2905 3268 3631
25 378 756 1134 1512 1890 2268 2646 3025 3403 3781

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