Flow Coefficient, Opening and Closure Curves of Butterfly Valves

Flow Coefficient, Opening and Closure Curves of Butterfly Valves

• Flow Coefficient and Flow Factor Values
• Cv & Kv Fraction vs Angle Closure Curve Chart
• Cv vs Angle Closure Curve Tables
• Kv vs Angle Closure Curve Tables
• See Also

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:

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

• Flow Coefficient, Cv, and Flow Factor, Kv, Converter