Butterfly Valves Flow Rate

 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.

 

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