Butterfly Valves

Even though we work on a metric system, measures of flow are commonly given as a CV value which is an; Imperial measure flow in US gallons per minute of water at 60° fahrenheit with pressure drop of 1 psi across the valve. Below is a table of the flow rates for Butterfly Valves at different opening stages between zero degrees (fully closed) and ninety degrees (fully open). Please note that a CV value is not a linear progression so it cannot be extrapolated out just by looking at the values, it is really just meant to give you a comparison flow rate.

Concentric Butterfly Valves

Size Cv Value at different degrees of opening
inch mm 10° 20° 30° 40° 50° 60° 70° 80° 90°
2 50 0.1 5 12 24 45 64 90 125 135
2 1/2 65 0.2 8 20 37 65 98 144 204 220
3 80 0.3 12 22 39 70 116 183 275 302
4 100 0.5 17 36 78 139 230 364 546 600
5 125 0.8 29 61 133 237 392 620 930 1022
6 150 2 45 95 205 366 605 958 1437 1579
8 200 3 89 188 408 727 1202 1903 2854 3136
10 250 4 151 320 694 1237 2047 3240 4859 5340
12 300 5 234 495 1072 1911 3162 5005 7507 8250
14 350 6 338 715 1549 2761 4568 7230 10844 11917
16 400 8 464 983 2130 3797 6282 9942 14913 16388
18 450 11 615 1302 2822 5028 8320 13168 19752 21705
20 500 14 791 1674 3628 6465 10698 16931 25396 27908
22 550 17 965 2042 4426 7887 13052 20655 30983 34048
24 600 22 1222 2587 5605 9989 16528 26157 39236 43116
26 650 26 1434 3036 6578 11723 19397 29263 46047 50600
28 700 30 1663 3522 7630 12599 20036 30482 46899 58696
30 750 35 1912 4050 8142 13152 20411 31226 47562 63328
32 800 45 2387 4791 8736 13788 20613 31395 48117 68250
34 850 51 2697 5414 9872 15580 23293 35476 54372 77123
36 900 60 3021 6063 11055 17449 26086 39731 60895 86375
40 1000 84 4183 8395 15307 24159 36166 55084 84425 119750
42 1050 350 4095 9040 17108 27150 43640 70500 106890 117500
48 1200 455 5365 11840 22400 30600 51200 92300 140000 154000

 

Triple Offset Butterfly Valves

Featuring offsets on the stem and valve sealing, the flow rate through the valve varies to conventional concentric Butterfly valves.

Valve Size Cv Value at different degrees of opening
NPS DN 10° 20° 30° 40° 50° 60° 70° 80° 90°
3 80 4.7 16.6 33.1 52.1 78.3 110 190 210 240
4 100 8.4 29.3 58.6 92 140 200 330 370 420
5 125 13.8 48.4 96.5 160 230 330 550 610 700
6 150 20.9 73.7 150 230 350 500 820 930 1050
8 200 38.2 140 270 420 640 900 1500 1690 1920
10 250 59 210 410 650 970 1370 2280 2570 2920
12 300 88.4 310 620 980 1460 2080 3450 3890 4420
14 350 110 390 770 1200 1800 2570 4260 4800 5460
16 400 150 530 1060 1660 2490 3540 5870 6620 7520
18 450 200 700 1390 2180 3260 4640 7700 8690 9870
20 500 270 930 1850 2900 4350 6190 10300 11600 13200
24 600 420 1450 2890 4530 6800 9680 16100 18100 20600
26 65 490 1720 3430 5390 8090 11500 19100 21600 24500
28 700 570 1990 3980 6260 9380 13400 22200 25000 28400
30 750 660 2300 4600 7230 10800 15400 25600 28900 32800
32 800 810 2820 5630 8840 13300 18900 31400 35400 40200
34 850 950 3300 6590 10400 15600 22100 36700 41400 47000
36 900 1080 3780 7550 11900 17800 25300 42100 47400 53900
38 950 1210 4200 8400 13200 79800 28200 46800 52800 60000
40 1000 1380 4710 9610 15100 22600 32300 53600 60400 68600
42 1050 1480 5150 10300 16200 24300 34600 57400 64700 73500
44 1100 1710 5970 11900 18800 28100 40100 66600 75000 85300
46 1150 1940 6800 13600 21400 32100 45600 75700 85400 97000
48 1200 2040 7140 14300 22400 33700 48000 79500 89700 102000