Valve Cv (Flow Coefficient) Table & Calculator
Complete Cv reference for Gate, Globe, Ball, Butterfly & Check valves from DN 15 to DN 600 (NPS ½" to 24"). Use the interactive calculator and sizing formulas below for accurate valve selection.
Last updated: March 2026 • Data per ISA/IEC 60534, API 598 & manufacturer test reports
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| DN (mm) | NPS (inch) | Valve Type | Cv | Kv (m³/hr) | Flow Rate (m³/hr @ 1 bar) |
% Full Bore | Typical Application |
|---|
Engineering Note: Cv values shown are typical full-open values for standard-port designs and may vary ±15% based on manufacturer, trim design, and seat configuration. Always verify against the manufacturer's certified Cv data sheet for critical sizing. Reduced-port valves will have lower Cv values.
Cv is measured per ISA-75.02 / IEC 60534-2-3. Flow rates assume water at 15°C (60°F), SG = 1.0, ΔP = 1 bar.
Cv vs. DN by Valve Type
Ball and Butterfly valves provide the highest Cv (least flow restriction) for any given DN. Globe valves offer the lowest Cv due to their tortuous flow path, making them ideal for throttling applications where pressure drop control is desired.
Flow Rate Calculator
Enter known parameters to calculate flow rate or required Cv. Supports liquids and gases.
Liquid Flow Rate from Cv
Required Cv from Flow Rate
Cv Sizing Formulas
Industry-standard equations per ISA-75.01 / IEC 60534-2-1 for valve sizing across different fluid types.
Liquids (Incompressible)
- Q
- Flow rate in US GPM
- Cv
- Flow coefficient
- ΔP
- Pressure drop across valve (psi)
- SG
- Specific gravity (water = 1.0)
Gas / Air (Subcritical)
- Q
- Flow rate in SCFH
- P1, P2
- Upstream / downstream pressure (psia)
- T
- Absolute temperature (°R = °F + 460)
- SG
- Gas specific gravity (air = 1.0)
- N
- Numerical constant (varies by units)
Steam
- W
- Mass flow rate in lb/hr
- ΔP
- Pressure drop across valve (psi)
- γ
- Steam density at inlet (lb/ft³)
- Cv
- Flow coefficient
For superheated steam, use degree of superheat correction factor.
Cv / Kv Conversion Reference
Cv → Kv
Kv = 0.865 × Cv
Kv is the metric flow coefficient (m³/hr of water at ΔP = 1 bar)
Kv → Cv
Cv = 1.156 × Kv
Used when converting European valve data to ANSI/ISA standards
Cv → Flow Rate
Q (m³/hr) = Kv × √(ΔP / SG)
Where ΔP is in bar and SG relative to water
| Cv | Kv (m³/hr) | Cv | Kv (m³/hr) | Cv | Kv (m³/hr) |
|---|---|---|---|---|---|
| 1 | 0.87 | 50 | 43.3 | 1000 | 865 |
| 5 | 4.33 | 100 | 86.5 | 2000 | 1730 |
| 10 | 8.65 | 200 | 173 | 5000 | 4325 |
| 15 | 13.0 | 300 | 260 | 10000 | 8650 |
| 25 | 21.6 | 500 | 433 | 20000 | 17300 |
Valve Type Comparison for Engineers
Selecting the right valve type depends on your application requirements. This comparison covers key engineering parameters.
| Parameter | Gate | Globe | Ball | Butterfly | Check (Swing) |
|---|---|---|---|---|---|
| Relative Cv (same DN) | High | Low | Highest | High | Medium |
| Throttling Ability | Poor | Excellent | Fair (V-port: Good) | Fair | Not applicable |
| Shut-off (Leakage Class) | Class IV–V | Class IV–V | Class VI (zero leakage) | Class IV–VI | Class II–IV |
| Pressure Drop (full open) | Very Low | High | Very Low | Low | Medium |
| Operating Torque | High (multi-turn) | Medium (multi-turn) | Low (quarter-turn) | Low (quarter-turn) | N/A (self-acting) |
| Actuator Suitability | Electric, Pneumatic | Electric, Pneumatic, Diaphragm | Pneumatic, Electric | Pneumatic, Electric | N/A |
| Flow Characteristic | Quick opening | Linear / Equal % | Modified equal % | Equal percentage | N/A |
| Max Temperature | Up to 650°C | Up to 650°C | Up to 350°C (soft seat) / 550°C (metal seat) | Up to 300°C (rubber) / 600°C (metal) | Up to 550°C |
| Best For | On/off isolation, pipelines | Throttling, flow control | Quick shut-off, tight sealing | Large-diameter isolation | Backflow prevention |
| Key Standard | API 600, BS 1414 | API 623, BS 1873 | API 608, BS 5351 | API 609, BS EN 593 | API 594, BS 1868 |
Valve Selection Guide
Use this decision framework to select the optimal valve type for your process conditions.
On/Off Isolation
Recommended: Gate Valve (small bore), Butterfly Valve (large bore), Ball Valve (critical sealing)
Prioritize low ΔP and high Cv. Avoid globe valves for isolation-only service.
Flow Throttling & Control
Recommended: Globe Valve (best), V-port Ball Valve, Butterfly with positioner
Globe valve's linear/equal-% characteristic offers the most predictable control. Check rangeability (≥50:1 for globe).
High Flow / Low ΔP
Recommended: Full-bore Ball Valve, Butterfly Valve
Maximum Cv with minimal flow restriction. Ball valves offer near-zero pressure drop when fully open.
Critical / Severe Service
Recommended: Metal-seated Ball Valve, Bellow-seal Globe Valve
For high temperature, high pressure, toxic, or fugitive emissions control. Consider API 624 / ISO 15848 certified valves.