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Engineering ToolBox > Butterfly Valves - Typical Flow Coefficients - Cv
The table below can be used as an indication of butterfly valves and their flow coefficients at different open (or closed) positions. Manufacturer data should always be checked.
| Flow Coefficient - Cv | |||||||
| Valve Size | Disc Angle - Openness | Maximum flow velocity (ft/sec) | |||||
| inches | mm | 90 deg (wide open) | 70 deg | 50 deg | 30 deg | ANSI 150 | ANSI 300 |
| 2 | 50 | 85 | 65 | 35 | 15 | 90 | 90 |
| 2 | 65 | 160 | 120 | 65 | 29 | 80 | 90 |
| 3 | 80 | 260 | 195 | 104 | 47 | 80 | 80 |
| 4 | 100 | 475 | 356 | 190 | 86 | 80 | 80 |
| 5 | 125 | 770 | 577 | 308 | 139 | 80 | 80 |
| 6 | 150 | 1125 | 844 | 450 | 203 | 75 | 80 |
| 8 | 200 | 2110 | 1583 | 844 | 380 | 70 | 75 |
| 10 | 250 | 3350 | 2513 | 1340 | 603 | 60 | 70 |
| 12 | 300 | 4800 | 3600 | 1920 | 864 | 50 | 60 |
| 14 | 350 | 6900 | 5175 | 2760 | 1224 | 50 | |
| 16 | 400 | 9000 | 6750 | 3600 | 1620 | 50 | |
| 18 | 450 | 11800 | 8850 | 4720 | 2124 | 50 | |
| 20 | 500 | 14300 | 10725 | 5720 | 2574 | 50 | |