Butterfly Valve Flow Coefficients

U.S. Gallons per minute Water at Pressure drop 1 Psi
VANE ANGLE (degrees)
VALVE SIZE (inches)	WIDE OPEN 90	80	70	60	50	40	30	20	FULL CLOSED 0
54	178,000	113,000	67,000	43,000	28,000	18,000	11,000	6,600	0
60	219,000	140,000	83,000	53,000	34,000	22,000	14,000	8,100	0
66	265,000	170,000	100,000	65,000	41,000	27,000	17,000	9,800	0
72	316,000	202,000	119,000	77,000	49,000	32,000	20,000	12,000	0
78	370,000	237,000	140,000	90,000	58,000	37,000	24,000	14,000	0
84	430,000	275,000	162,000	105,000	67,000	43,000	28,000	16,000	0
92	515,000	329,000	195,000	126,000	80,000	52,000	33,000	19,000	0
96	561,000	359,000	212,000	137,000	87,000	56,000	36,000	21,000	0
108	681,000	382,000	258,000	170,000	105,000	68,000	42,000	25,200	0
114	804,000	451,000	304,000	201,000	124,000	80,000	50,000	30,000	0
120	949,000	532,000	359,000	237,000	146,000	94,000	59,000	35,000	0
132	1,120,000	628,000	424,000	280,000	172,000	111,000	70,000	41,000	0
144	1,322,000	741,000	500,000	330,000	203,000	131,000	83,000	48,000	0