Valve Cv / Kv calculator 阀门流量系数计算器
The flow coefficient Cv tells you how much a valve will pass at a given pressure drop. Use this calculator to size a valve for a duty, or to check the Cv a supplier has quoted.
Cv 表示阀门在单位压差下能通过的流量。用它可以反算所需 Cv，也可以核对供应商报价的 Cv 是否合理。
- Liquid 液体: Cv = Q(gpm) × √(SG / ΔP)，并自动判断是否达到阻塞流
- Gas 气体: 按 ISA 简化式计算标准流量下的 Cv，超过临界压差时按 FL 修正并提示
Result is a preliminary size. Final selection also depends on flashing/cavitation, noise, turndown and the manufacturer's actual Cv table — which is what we quote against.
How to use it / 使用说明： Cv/Kv 计算器使用说明 — How to use this calculator — worked examples and the five mistakes that give wrong sizes.
m³/h × 4.403 = US gpm
水 = 1.00，柴油约 0.85
psig（表压）
psi
| 等值 Kv（m³/h @ 1 bar） | — |
| 建议选阀口径参考 Suggested size | — |
| 流动状态 Flow regime | — |
Cv = Q(gpm) × √(SG / ΔP)
计算基于 ISA/IEC 60534 简化式，用于初步选型。液体按紊流、无闪蒸/气蚀判断；气体按非临界流计算，超过临界压差时按 ΔPallow = FL² × P1 修正并提示。
Preliminary sizing only. Confirm the final selection against the manufacturer's Cv table, flashing/cavitation limits and noise limits — or send the duty to websale@sawye.com and we will size it and quote it.