Flow Coefficient, Opening and Closure Curves of Butterfly Valves

Flow Coefficient, Opening and Closure Curves of Butterfly Valves

Flow Coefficient and Flow Factor Values

The table below list typical maximum flow coefficient, Cv, and flow factor, Kv, values for butterfly valves:

Nominal Diameter Max Cv Max Kv
Inch mm gpm.psi (m³/hr).bar
6″ 150 950 822
8″ 200 1725 1492
10″ 250 2800 2422
12″ 300 4175 3611
14″ 350 5850 5060
16″ 400 7850 6790
18″ 450 10200 8823
20″ 500 12900 11159
24″ 600 19375 16759
26″ 650 23200 20068
28″ 700 27450 23744
30″ 750 32100 27767
32″ 800 37200 32178
36″ 900 48800 42212
40″ 1000 62325 53911
42″ 1050 69850 60420
48″ 1200 95775 82845

Cv & Kv Fraction vs Angle Closure Curve Chart

This graph shows the Cv or Kv valve fraction vs opening and closing angle of a butterfly valve:

Butterfly Valve Cv and Kv Fraction vs Angle

The full closure curve of a butterfly valve is then the above graph multiplied by the valve’s flow coefficient or factor.

Cv vs Angle Closure Curve Values Table

The tables below list the full Cv vs angle closure and opening curves for various valve diameters:

Butterfly Valve Cv vs Angle for Different Imperial Diameters
  6″ 8″ 10″ 12″
0° 0 0 0 0
10° 31 56 91 135
20° 71 128 208 310
30° 127 231 375 559
40° 217 394 640 954
50° 331 601 976 1455
60° 475 862 1399 2087
70° 680 1235 2005 2989
80° 887 1611 2615 3900
90° 950 1725 2800 4175
 
  14″ 16″ 18″ 20″
0° 0 0 0 0
10° 190 254 330 418
20° 435 583 758 958
30° 784 1052 1367 1729
40° 1336 1793 2330 2946
50° 2039 2736 3555 4496
60° 2924 3923 5098 6447
70° 4188 5620 7302 9235
80° 5464 7333 9528 12050
90° 5850 7850 10200 12900
 
  24″ 26″ 28″ 30″
0° 0 0 0 0
10° 628 752 889 1040
20° 1440 1724 2040 2385
30° 2596 3109 3678 4301
40° 4425 5299 6270 7332
50° 6752 8085 9566 11187
60° 9684 11595 13720 16044
70° 13871 16609 19651 22980
80° 18098 21671 25641 29985
90° 19375 23200 27450 32100
 
  32″ 36″ 40″ 42″
0° 0 0 0 0
10° 1205 1581 2019 2263
20° 2764 3626 4631 5190
30° 4985 6539 8352 9360
40° 8496 11146 14235 15954
50° 12964 17007 21720 24343
60° 18593 24390 31150 34911
70° 26631 34936 44618 50006
80° 34749 45584 58218 65247
90° 37200 48800 62325 69850
 
  48″
0° 0
10° 3103
20° 7116
30° 12834
40° 21875
50° 33378
60° 47868
70° 68565
80° 89463
90° 95775

Kv vs Angle Closure Curve Values Table

The tables below list the full Kv vs angle closure and opening curves for various metric valve diameters:

Butterfly Valve Kv vs Angle for Different Diameters
(mm) 150 200 250 300
0° 0 0 0 0
10° 27 48 78 117
20° 61 111 180 268
30° 110 200 325 484
40° 188 341 553 825
50° 286 520 844 1259
60° 411 746 1211 1805
70° 588 1068 1734 2585
80° 768 1394 2262 3373
90° 822 1492 2422 3611
 
(mm) 350 400 450 500
0° 0 0 0 0
10° 164 220 286 362
20° 376 505 656 829
30° 678 910 1182 1495
40° 1156 1551 2015 2549
50° 1763 2366 3075 3889
60° 2529 3394 4410 5577
70° 3623 4861 6316 7988
80° 4727 6343 8242 10423
90° 5060 6790 8823 11159
 
(mm) 600 650 700 750
0° 0 0 0 0
10° 543 650 769 900
20° 1245 1491 1764 2063
30° 2246 2689 3182 3721
40° 3828 4584 5423 6342
50° 5841 6994 8275 9677
60° 8376 10030 11867 13878
70° 11998 14367 16999 19878
80° 15655 18746 22180 25937
90° 16759 20068 23744 27767
 
(mm) 800 900 1000 1050
0° 0 0 0 0
10° 1043 1368 1747 1958
20° 2391 3136 4006 4489
30° 4312 5656 7224 8096
40° 7349 9641 12313 13800
50° 11214 14711 18788 21056
60° 16083 21098 26945 30198
70° 23036 30220 38595 43255
80° 30057 39430 50358 56439
90° 32178 42212 53911 60420
 
(mm) 1200
0° 0
10° 2684
20° 6155
30° 11101
40° 18922
50° 28872
60° 41406
70° 59309
80° 77386
90° 82845

See Also