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Water Control Valves - K_v Calculation

Designing 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

For full table - rotate the screen!

K_v
Pressure drop		Water flow (kg/h)
Pressure drop		36	72	108	144	180	360	720	1080	1440	1800	3600
(kPa)	(bar)	Water flow (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	1.1	1.4	1.8	3.6	7.2	10.8	14.4	18.0	36.0
2	0.02	0.25	0.51	0.76	1.0	1.3	2.6	5.1	7.6	10.2	12.7	25.5
3	0.03	0.21	0.42	0.62	0.83	1.0	2.1	4.2	6.2	8.3	10.4	20.8
4	0.04	0.18	0.36	0.54	0.72	0.90	1.8	3.6	5.4	7.2	9.0	18.0
5	0.05	0.16	0.32	0.48	0.64	0.80	1.6	3.2	4.8	6.4	8.1	16.1
10	0.1	0.11	0.23	0.34	0.46	0.57	1.1	2.3	3.4	4.6	5.7	11.4
20	0.2	0.08	0.16	0.24	0.32	0.40	0.80	1.6	2.4	3.2	4.0	8.1
30	0.3	0.07	0.13	0.2	0.26	0.33	0.66	1.3	2.0	2.6	3.3	6.6
40	0.4	0.06	0.11	0.17	0.23	0.28	0.57	1.1	1.7	2.3	2.9	5.7
50	0.5	0.05	0.10	0.15	0.20	0.25	0.51	1.0	1.5	2.0	2.6	5.1
100	1	0.04	0.07	0.11	0.14	0.18	0.36	0.72	1.1	1.4	1.8	3.6
200	2	0.03	0.05	0.08	0.10	0.13	0.25	0.51	0.76	1.0	1.3	2.6
300	3	0.02	0.04	0.06	0.08	0.10	0.21	0.42	0.62	0.83	1.0	2.1
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	1.6
1000	10	0.01	0.02	0.03	0.05	0.06	0.11	0.23	0.34	0.46	0.57	1.1
2000	20	0.01	0.02	0.02	0.03	0.04	0.08	0.16	0.24	0.32	0.40	0.80
3000	30	0.01	0.01	0.02	0.03	0.03	0.07	0.13	0.20	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

For full table - rotate the screen!

K_v
Pressure drop		Water flow (kg/h)
Pressure drop		7200	10800	14400	18000	36000	72000	108000	144000	180000	360000	720000
(kPa)	(bar)	Water flow (kg/s)
(kPa)	(bar)	2	3	4	5	10	20	30	40	50	100	200
1	0.01	72.0	108	144	180	360	720	1080	1440	1800	3600	7200
2	0.02	50.9	76.4	102	127	254	509	763	1019	1273	2546	5091
3	0.03	41.6	62.4	83.1	103	207	415	623	831	1039	2078	4157
4	0.04	36.0	54.0	72.0	90.0	180	360	540	720	900	1800	3600
5	0.05	32.2	48.3	64.4	80.5	161	321	483	644	805	1610	3220
10	0.1	22.8	34.2	45.5	56.9	113	227	342	455	569	1138	2277
20	0.2	16.1	24.2	32.2	40.3	80.5	161	242	322	402	805	1610
30	0.3	13.2	19.7	26.3	32.9	65.7	131	197	263	329	657	1315
40	0.4	11.4	17.1	22.8	28.5	56.9	114	171	228	285	569	1138
50	0.5	10.2	15.3	20.4	25.5	50.9	102	153	204	255	509	1018
100	1	7.2	10.8	14.4	18.0	36.0	72.0	108	144	180	360	720
200	2	5.1	7.6	10.2	12.7	25.5	50.9	76.4	102	127	255	509
300	3	4.2	6.2	8.3	10.4	20.8	41.6	62.4	83.1	104	208	416
400	4	3.6	5.4	7.2	9.0	18.0	36.0	54.0	72.0	90.0	180	360
500	5	3.2	4.8	6.4	8.1	16.1	32.2	48.3	64.4	80.5	161	322
1000	10	2.3	3.4	4.6	5.7	11.4	22.8	34.2	45.5	56.9	114	228
2000	20	1.6	2.4	3.2	4.0	8.1	16.1	24.2	32.2	40.3	80.5	161
3000	30	1.3	2.0	2.6	3.3	6.6	13.2	19.7	26.3	32.9	65.7	131
4000	40	1.1	1.7	2.3	2.9	5.7	11.4	17.1	22.8	28.5	56.9	114

Download Water Flow Kv Diagram

Example - K_v for a Water Control Valve

For a water control valve with

pressure drop 2 bar
water flow 1 kg/s

- the K_v value should be approximately 2.6 according the table above.

K_v can be calculated as:

K_v = q / (dp)^1/2 (1)

where

K_v = K_v value

q = water flow (m³/h)

dp = pressure drop (bar)

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Related Topics

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

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