Globe Valve Cv Value
The Cv value (flow coefficient) of a globe valve indicates how much water (in US gallons per minute) will flow through the valve with a 1 PSI pressure drop. Globe valves have lower Cv values than gate or ball valves because of their tortuous S-shaped flow path, which makes them ideal for throttling and flow control applications.
Quick Answer: What is Globe Valve Cv Value?
Cv is the flow coefficient - the number of US gallons per minute (GPM) of water at 60°F that flows through a valve with a 1 PSI pressure drop. For globe valves, typical Cv values range from 0.14 (½" valve) to 1100+ (24" valve). A 2" globe valve has Cv ≈ 46, while a 4" globe valve has Cv ≈ 195.
Globe Valve Cv Value Chart
The following table shows typical Cv values for standard globe valves by size and pressure class. Values may vary by manufacturer and valve design (standard, Y-pattern, angle).
| Size (inches) | DN (mm) | Class 150 | Class 300 | Class 600 | Class 900 | Class 1500 |
|---|---|---|---|---|---|---|
| ½" | 15 | 5.5 | 5.0 | 4.5 | 4.0 | 3.5 |
| ¾" | 20 | 9.5 | 9.0 | 8.0 | 7.0 | 6.0 |
| 1" | 25 | 17 | 16 | 14 | 12 | 10 |
| 1½" | 40 | 32 | 30 | 26 | 22 | 18 |
| 2" | 50 | 46 | 43 | 38 | 32 | 26 |
| 2½" | 65 | 75 | 70 | 62 | 52 | 42 |
| 3" | 80 | 110 | 100 | 90 | 75 | 60 |
| 4" | 100 | 195 | 180 | 160 | 135 | 110 |
| 5" | 125 | 300 | 280 | 250 | 210 | 170 |
| 6" | 150 | 440 | 410 | 365 | 305 | 250 |
| 8" | 200 | 780 | 725 | 645 | 540 | 440 |
| 10" | 250 | 1200 | 1120 | 1000 | 835 | 680 |
| 12" | 300 | 1750 | 1630 | 1450 | 1210 | 990 |
| 14" | 350 | 2100 | 1960 | 1740 | 1455 | 1190 |
| 16" | 400 | 2750 | 2560 | 2280 | 1905 | 1555 |
| 18" | 450 | 3500 | 3260 | 2900 | 2425 | 1980 |
| 20" | 500 | 4300 | 4005 | 3565 | 2980 | 2435 |
| 24" | 600 | 6200 | 5775 | 5140 | 4295 | 3510 |
Note: Values are for standard globe valves (full port). Y-pattern globe valves have ~20-30% higher Cv. Reduced port valves have lower Cv. Always verify with manufacturer data sheets.
Globe Valve Cv Formula
Cv Calculation Formula
For liquids (water, oil, etc.):
Where:
- Cv = Flow coefficient
- Q = Flow rate in US gallons per minute (GPM)
- SG = Specific gravity (1.0 for water)
- ΔP = Pressure drop across valve in PSI
Cv = 100 × √(1.0 / 4) = 100 × 0.5 = 50
Select a globe valve with Cv ≥ 50 (e.g., 2½" Class 150 with Cv = 75)
For Gases and Steam
Where: T = temperature (°R), P1 = inlet pressure (PSIA), SG = specific gravity vs air
Cv Calculator
Calculate Required Cv (Liquids)
Cv vs Kv Conversion
Cv to Kv
Kv is in m³/h at 1 bar ΔP (European standard)
Kv to Cv
Cv is in GPM at 1 PSI ΔP (US standard)
Globe Valve vs Other Valve Types - Cv Comparison
Globe valves have significantly lower Cv values compared to gate and ball valves due to their flow path design:
| Size | Globe Valve Cv | Gate Valve Cv | Ball Valve Cv | Butterfly Valve Cv |
|---|---|---|---|---|
| 2" (DN50) | 46 | 200 | 350 | 300 |
| 4" (DN100) | 195 | 800 | 1400 | 1200 |
| 6" (DN150) | 440 | 1800 | 3150 | 2700 |
| 8" (DN200) | 780 | 3200 | 5600 | 4800 |
Why the difference? Globe valves force fluid through an S-shaped path with multiple direction changes, creating higher resistance. This is intentional - it provides precise throttling control. Gate and ball valves have straight-through flow paths for minimal pressure drop.
Frequently Asked Questions
What is Cv value in a globe valve?
Cv (flow coefficient) is the number of US gallons per minute of water at 60°F that will flow through a valve with a pressure drop of 1 PSI. For globe valves, Cv values typically range from 0.14 (1/2" valve) to 1100+ (24" valve). Globe valves have lower Cv values than gate or ball valves due to their tortuous flow path designed for throttling.
What is the Cv value of a 2 inch globe valve?
A 2 inch (DN50) globe valve typically has a Cv value between 35-70 depending on the design. Standard globe valves are around 46 Cv, while Y-pattern globe valves can reach 70 Cv due to their straighter flow path. Control valves may have adjustable Cv based on trim design.
How do you calculate Cv for a globe valve?
The Cv formula for liquids is: Cv = Q × √(SG / ΔP), where Q = flow rate in GPM, SG = specific gravity (1.0 for water), and ΔP = pressure drop in PSI. For example, if you need 50 GPM with 4 PSI drop: Cv = 50 × √(1/4) = 50 × 0.5 = 25. Select a valve with Cv ≥ 25.
What is the difference between Cv and Kv?
Cv uses US gallons per minute (GPM) and PSI, while Kv uses cubic meters per hour (m³/h) and bar. To convert: Kv = 0.865 × Cv, or Cv = 1.156 × Kv. Cv is standard in USA, while Kv is used in Europe and metric countries.
Why do globe valves have lower Cv than gate valves?
Globe valves have an S-shaped or tortuous flow path where fluid must change direction multiple times, creating higher resistance. This design is intentional - it provides excellent throttling control but results in Cv values 3-5x lower than gate valves of the same size. Gate valves have a straight-through flow path with minimal restriction.
Need Help Sizing Your Globe Valve?
Our engineers can help you select the right globe valve for your application. Send us your flow requirements and we'll provide sizing recommendations.