Water Control Valves - Calculating Kv Values

Design of water process control valves and their K_v values

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The table below can be used to estimate the K_v values for process control valves used in water systems.

Go to the left column and select the pressure drop for the valve
Go right in table close to the actual water flow. Interpolate to find the approximately K_v value

K_v		Water flow
Pressure drop		(kg/h)
Pressure drop		36	72	108	144	180	360	720	1080	1440	1800	3600
(kPa)	(bar)	(kg/s)
(kPa)	(bar)	0.01	0.02	0.03	0.04	0.05	0.1	0.2	0.3	0.4	0.5	1
1	0.01	0.36	0.72	1.08	1.44	1.8	3.6	7.2	10.8	14.4	18	36
2	0.02	0.25	0.51	0.76	1.02	1.27	2.55	5.09	7.64	10.18	12.73	25.46
3	0.03	0.21	0.42	0.62	0.83	1.04	2.08	4.16	6.24	8.31	10.39	20.78
4	0.04	0.18	0.36	0.54	0.72	0.9	1.8	3.6	5.4	7.2	9	18
5	0.05	0.16	0.32	0.48	0.64	0.8	1.61	3.22	4.83	6.44	8.05	16.1
10	0.1	0.11	0.23	0.34	0.46	0.57	1.14	2.28	3.42	4.55	5.69	11.38
20	0.2	0.08	0.16	0.24	0.32	0.4	0.8	1.61	2.41	3.22	4.02	8.05
30	0.3	0.07	0.13	0.2	0.26	0.33	0.66	1.31	1.97	2.63	3.29	6.57
40	0.4	0.06	0.11	0.17	0.23	0.28	0.57	1.14	1.71	2.28	2.85	5.69
50	0.5	0.05	0.1	0.15	0.2	0.25	0.51	1.02	1.53	2.04	2.55	5.09
100	1	0.04	0.07	0.11	0.14	0.18	0.36	0.72	1.08	1.44	1.8	3.6
200	2	0.03	0.05	0.08	0.1	0.13	0.25	0.51	0.76	1.02	1.27	2.55
300	3	0.02	0.04	0.06	0.08	0.1	0.21	0.42	0.62	0.83	1.04	2.08
400	4	0.02	0.04	0.05	0.07	0.09	0.18	0.36	0.54	0.72	0.9	1.8
500	5	0.02	0.03	0.05	0.06	0.08	0.16	0.32	0.48	0.64	0.8	1.61
1000	10	0.01	0.02	0.03	0.05	0.06	0.11	0.23	0.34	0.46	0.57	1.14
2000	20	0.01	0.02	0.02	0.03	0.04	0.08	0.16	0.24	0.32	0.4	0.8
3000	30	0.01	0.01	0.02	0.03	0.03	0.07	0.13	0.2	0.26	0.33	0.66
4000	40	0.01	0.01	0.02	0.02	0.03	0.06	0.11	0.17	0.23	0.28	0.57

K_v		Water flow
Pressure drop		(kg/h)
Pressure drop		7200	10800	14400	18000	36000	72000	108000	144000	180000	360000	720000
(kPa)	(bar)	(kg/s)
(kPa)	(bar)	2	3	4	5	10	20	30	40	50	100	200
1	0.01	72	108	144	180	360	720	1080	1440	1800	3600	7200
2	0.02	50.91	76.37	101.82	127.28	254.56	509.12	763.68	1018.23	1272.79	2545.58	5091.17
3	0.03	41.57	62.35	83.14	103.92	207.85	415.69	623.54	831.38	1039.23	2078.46	4156.92
4	0.04	36	54	72	90	180	360	540	720	900	1800	3600
5	0.05	32.2	48.3	64.4	80.5	161	321.99	482.99	643.99	804.98	1609.97	3219.94
10	0.1	22.77	34.15	45.54	56.92	113.84	227.68	341.53	455.37	569.21	1138.42	2276.84
20	0.2	16.1	24.15	32.2	40.25	80.5	161	241.5	321.99	402.49	804.98	1609.97
30	0.3	13.15	19.72	26.29	32.86	65.73	131.45	197.18	262.91	328.63	657.27	1314.53
40	0.4	11.38	17.08	22.77	28.46	56.92	113.84	170.76	227.68	284.6	569.21	1138.42
50	0.5	10.18	15.27	20.36	25.46	50.91	101.82	152.74	203.65	254.56	509.12	1018.23
100	1	7.2	10.8	14.4	18	36	72	108	144	180	360	720
200	2	5.09	7.64	10.18	12.73	25.46	50.91	76.37	101.82	127.28	254.56	509.12
300	3	4.16	6.24	8.31	10.39	20.78	41.57	62.35	83.14	103.92	207.85	415.69
400	4	3.6	5.4	7.2	9	18	36	54	72	90	180	360
500	5	3.22	4.83	6.44	8.05	16.1	32.2	48.3	64.4	80.5	161	321.99
1000	10	2.28	3.42	4.55	5.69	11.38	22.77	34.15	45.54	56.92	113.84	227.68
2000	20	1.61	2.41	3.22	4.02	8.05	16.1	24.15	32.2	40.25	80.5	161
3000	30	1.31	1.97	2.63	3.29	6.57	13.15	19.72	26.29	32.86	65.73	131.45
4000	40	1.14	1.71	2.28	2.85	5.69	11.38	17.08	22.77	28.46	56.92	113.84

Example - K_v for a Water Control Valve

With a pressure drop of 2 bar, a water flow of 1 kg/s, the K_v value should be approximately 2.55.

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Related Topics

Water Systems Hot and cold water systems - design properties, capacities, sizing and more
Process Control Instrumentation and process control systems - engineering and documentation
Control Valves Control Valve terminology, bodies, trim, flow characteristics, Cv and Kv sizing, noise, actuators and positioners

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