Products

Flange Process Picture

Butterfly Valve

High Performance Butterfly Valve

Technical Data

Torque

Cv,Kv

MSDS

Vacuum Service

Operating Characteristics for sizing

▣ The size of butterfly valve used for control purpose should be calculated on the
basis of the operating characteristics.

In order to achieve optimum control, the flow coefficient ( Cv, Kv ) below need to be
considered

▣ Flow Coefficient for ST&H RUBBER SEAT Butterfly valves

SIZE		DISC OPENING
		20°		30°		40°		50°
		Kv	Cv	Kv	Cv	Kv	Cv	Kv	Cv
40	1½	2.6	3	4.3	5	9.5	11	16	18
50	2	6.7	8	7.8	9	16	18	24	28
65	2½	8.6	10	13	15	23	27	38	44
80	3	13	15	20	23	34	39	56	65
100	4	23	27	35	41	61	71	99	115
125	5	50	58	74	86	129	150	211	245
150	6	83	96	121	140	211	245	345	400
200	8	142	165	211	245	354	410	591	685
250	10	220	255	328	380	560	650	974	1130
300	12	319	370	466	540	819	950	1353	1570
350	14	388	450	647	750	1120	1300	1905	2210
400	16	552	640	776	900	1483	1720	2405	2790
450	18	630	730	1078	1250	1978	2295	3190	3700
500	20	785	910	1375	1595	2457	2850	3991	4630
600	24	1078	1250	1974	2290	3448	4000	5250	6090

SIZE		DISC OPENING
		60°		70°		80°		90°
		Kv	Cv	Kv	Cv	Kv	Cv	Kv	Cv
40	1½	22	26	39	45	60	70	69	80
50	2	48	55	62	72	95	110	116	135
65	2½	73	85	95	110	145	168	181	210
80	3	112	130	142	165	216	250	267	310
100	4	198	230	259	300	401	465	466	540
125	5	414	480	526	610	845	980	948	1100
150	6	677	785	871	1010	1392	1615	1647	1910
200	8	1099	1275	1478	1715	2302	2670	2746	3185
250	10	1810	2100	2328	2700	3664	4250	4224	4900
300	12	2629	3050	3405	3950	5129	5950	6336	7350
350	14	3517	4080	4836	5610	6964	8078	9655	11200
400	16	4310	5000	6336	7650	9284	10770	11121	12900
450	18	6078	7050	7914	9180	11983	13900	15086	17500
500	20	7414	8600	9914	11500	15121	17540	19310	22400
600	24	10776	12500	14224	16500	20336	23590	24397	28300

▣ Flow Coefficient for ST&H High Performance Butterfly valves

SIZE		DISC OPENING
		20°		30°		40°		50°
		Kv	Cv	Kv	Cv	Kv	Cv	Kv	Cv
50	2"	5.2	6	12.1	14	21.6	25	33.6	39
65	2½"	7.8	9	18.1	21	31.9	37	48.3	56
80	3"	12.1	14	27.6	32	49.1	57	75.0	87
100	4"	23.3	27	54.3	63	98.3	114	147.4	171
125	5"	37.1	43	86.2	100	155.2	180	233.6	271
150	6"	56.9	66	132.8	154	239.7	278	361.2	419
200	8"	106.9	124	249.1	289	448.3	520	675.9	784
250	10"	181.9	211	424.1	492	763.8	886	1151.7	1336
300	12"	250.0	290	583.6	677	1050.9	1219	1584.5	1838

SIZE		DISC OPENING
		60°		70°		80°		90°
		Kv	Cv	Kv	Cv	Kv	Cv	Kv	Cv
50	2"	48.3	56	65.5	76	85.3	99	87.9	102
65	2½"	69.0	80	94.8	110	122.4	142	125.9	146
80	3"	107.8	125	147.4	171	190.5	221	196.6	228
100	4"	213.8	248	291.4	338	376.7	437	388.8	451
125	5"	337.9	392	461.2	535	596.6	692	615.5	714
150	6"	523.3	607	712.9	827	922.4	1070	950.9	1103
200	8"	978.4	1135	1365.5	1584	1725.9	2002	1779.3	2064
250	10"	1667.2	1934	2274.1	2638	2940.5	3411	3031.9	3517
300	12"	2293.1	2660	3127.6	3628	4043.1	4690	4169.8	4837

◆ Cv is in imperial units, the water flow rate in U.S gallons per minute which passes through the valve giving a pressure drop of 1 psi at a temperature of 68℉

In metric units the same coefficient is called Kv and correspond to the flow rate in m3/h passing through the valve giving a pressure drop of 1 bar at a temperature of 20℃ The approximate
corresponding formulas are :

Q = valve flow rate in gpm (US GPM)
△p = pounds per square inch (psi)
pressure drop through the valve
62.4 = conversion factor for fluids
computed in relation to water
D = is pounds per cu.ft (pct) fluid
density

Q = valve flow rate in m3/h
△p = pressure drop through the valve
in bar
1000 = conversion factor for fluids
computed in computed in relation to
water relation to water
D = ㎏/m3 fluid density

The relation between Cv and Kv, expressed in the above mentioned unit of measure is as follows;

Cv = 1.16 Kv