Floating Control Valves
V-Port Control Valve Cv Rating by Size and Opening
Cv ratings are valid for valve series 700076, 710190, 630LL, 730LL, 770, 771, 710190, 724102, 720370, 760021, and 760195
| Valve Type | Press Class | SIZE [inch] | Openings (Degrees) | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| 10° | 20° | 30° | 40° | 50° | 60° | 70° | 80° | 90° | |||
| Cv | Cv | Cv | Cv | Cv | Cv | Cv | Cv | Cv | |||
| V 90° Port | 150-300 CLASS | 1/2" | 0 | 0.1 | 0.3 | 0.7 | 1.2 | 2.0 | 3.4 | 5.9 | 10 |
| 3/4" | 0 | 0.3 | 0.8 | 1.6 | 2.7 | 4.6 | 7.7 | 13.3 | 22 | ||
| 1" | 0 | 0.5 | 1.4 | 2.8 | 4.9 | 8.2 | 13.7 | 23.7 | 39 | ||
| 1-1/4” | 0 | 0.8 | 2.2 | 4.5 | 8.0 | 13.4 | 22.4 | 38.8 | 64 | ||
| 1-1/2” | 0 | 1.1 | 3.3 | 6.6 | 11.6 | 19.5 | 32.6 | 56.4 | 93 | ||
| 2" | 0 | 2.0 | 6.0 | 12.0 | 21.2 | 35.6 | 59.5 | 102.9 | 170 | ||
| 2-1/2” | 0.24 | 2.41 | 8.67 | 18.00 | 33.47 | 57.52 | 99.19 | 168.99 | 288.42 | ||
| 3" | 0 | 4.7 | 13.6 | 27.3 | 48.1 | 80.9 | 135.4 | 234.1 | 387 | ||
| 4" | 0 | 8.1 | 23.6 | 47.5 | 83.8 | 140.8 | 235.7 | 407.5 | 675 | ||
| 6" | 0 | 17.7 | 51.6 | 103.8 | 183.1 | 307.6 | 514.9 | 890.2 | 1473 | ||
| V 60° Port | 150-300 CLASS | ||||||||||
| 1/2" | 0 | 0.1 | 0.2 | 0.4 | 0.7 | 1.2 | 1.9 | 3.3 | 6 | ||
| 3/4" | 0 | 0.1 | 0.4 | 0.9 | 1.5 | 2.6 | 4.3 | 7.5 | 12 | ||
| 1" | 0 | 0.3 | 0.8 | 1.6 | 2.7 | 4.6 | 7.7 | 13.4 | 22 | ||
| 1-1/4” | 0 | 0.4 | 1.3 | 2.5 | 4.5 | 7.6 | 12.7 | 21.9 | 36 | ||
| 1-1/2” | 0 | 0.7 | 2.0 | 4.0 | 7.1 | 11.9 | 20.0 | 34.5 | 57 | ||
| 2" | 0 | 1.1 | 3.1 | 6.3 | 11.1 | 18.7 | 31.2 | 54.0 | 89 | ||
| 2-1/2” | 0.24 | 2.07 | 6.82 | 14.33 | 25.08 | 41.58 | 68.92 | 108.96 | 157.93 | ||
| 3" | 0 | 2.7 | 7.9 | 16.0 | 28.2 | 47.4 | 79.3 | 137.1 | 227 | ||
| 4" | 0 | 4.3 | 12.4 | 25.0 | 44.1 | 74.1 | 124.1 | 214.5 | 355 | ||
| 6" | 0 | 9.6 | 28.0 | 56.3 | 99.3 | 166.8 | 279.3 | 482.8 | 799 | ||
| V 30°-60° Port | 150-300 CLASS | ||||||||||
| 1/2" | 0 | 0.0 | 0.1 | 0.2 | 0.4 | 0.6 | 1.0 | 1.7 | 3 | ||
| 3/4" | 0 | 0.1 | 0.2 | 0.5 | 0.8 | 1.3 | 2.2 | 3.9 | 6 | ||
| 1" | 0 | 0.1 | 0.4 | 0.8 | 1.4 | 2.4 | 4.0 | 6.9 | 11 | ||
| 1-1/4” | 0 | 0.2 | 0.7 | 1.3 | 2.3 | 3.9 | 6.5 | 11.3 | 18 | ||
| 1-1/2” | 0 | 0.3 | 1.0 | 2.0 | 3.5 | 5.9 | 9.8 | 17.0 | 28 | ||
| 2" | 0 | 0.5 | 1.5 | 3.1 | 5.5 | 9.2 | 15.4 | 26.7 | 44 | ||
| 2-1/2” | 0.06 | 2.19 | 6.13 | 11.49 | 19.24 | 30.03 | 44.19 | 66.64 | 96.37 | ||
| 3" | 0 | 1.3 | 3.9 | 7.8 | 13.8 | 23.2 | 38.9 | 67.2 | 111 | ||
| 4" | 0 | 2.1 | 6.1 | 12.3 | 21.6 | 36.3 | 60.8 | 105.2 | 174 | ||
| 6" | 0 | 4.7 | 13.7 | 27.6 | 48.7 | 81.9 | 137.0 | 236.9 | 392 | ||
Below are the steps to calculate the Cv rating required for a V-port control valve:
1. Determine the required flow rate (Q) through the valve in gallons per minute (gpm) or cubic meters per hour (m3/hr). This should be known from your process requirements.
2. Determine the fluid properties:
- Density (ρ) in lb/ft3 or kg/m3
- Viscosity (μ) in centipoise (cP)
3. Determine the available differential pressure (ΔP) across the valve in psi or bar. This is the difference between inlet and outlet pressures.
4. Use the flow equation for liquids to calculate the required Cv:
Cv = Q / (N1 * √ΔP)
Where:
- Q = flow rate (gpm or m3/hr)
- N1 = conversion factor from unit consistency
- For liquid gpm: N1 = 1
- For liquid m3/hr: N1 = 3.67
- ΔP = differential pressure across the valve (psi or bar)
5. Select a V-port valve with an equal or higher Cv rating than the calculated value. Add a safety factor of 10-20% if possible. A valve with the calculated Cv rating at 70% to 80% opening would be ideal.
Example:
Cv rating calculation for a V-port valve to control the flow of saturated steam in a system with the following conditions:
- Flow rate (Q) = 1000 PPH
- Inlet pressure = 30 PSIA
- Outlet pressure = 10 PSIA
- Differential pressure (ΔP) = Inlet - Outlet = 30 - 10 = 20 PSI
- Specific gravity (SG) of steam = 0.6
The Cv equation for steam is:
Cv = Q / (N2 * √(SG * ΔP))
Where:
- N2 for steam flow in PPH is 83,000
Plugging in the values:
Cv = 1000 / (83,000 * √(0.6 * 20)) = 6.13
A V-port control valve with a Cv rating of at least 7.0 at 70% to 80% opening to provide some safety margin would be ideal. From the table above, either a 1" or 1-1/4" valve with a 30-60 V-port can be used for this application.
Please click here if you would like us to provide a comprehensive valve size report for your flow control requirements.