Control Valve Cv to Flow Converter

The Control Valve Cv to Flow Converter helps you quickly convert between valve flow coefficient (Cv) and liquid flow rate, using the standard valve sizing equation. By entering Cv, pressure drop, and specific gravity, you can estimate the flow rate; or you can calculate the required Cv for a given flow and pressure drop.

This tool is ideal for instrumentation engineers, process engineers, maintenance technicians, and valve vendors who work with liquid service valve sizing and selection.

Use this Control Valve Cv to Flow Converter whenever you:

• Estimate flow through an existing valve

• Check if a valve is undersized/oversized

• Need a quick Cv for preliminary valve selection

Introduction

1. Choose Mode:

   • “Cv → Flow” if you know Cv and want to calculate flow rate (Q).

   • “Flow → Cv” if you know desired flow rate and want to calculate required Cv.

2. Enter Valve Cv (for Cv → Flow mode) or Flow Rate (US gpm) (for Flow → Cv mode).

3. Enter Pressure Drop (ΔP) across the valve in psi.

4. Enter Specific Gravity (SG) of the liquid at operating temperature (water ≈ 1.0).

5. Click Calculate.

6. The result box shows the calculated Flow or Cv, plus the input values and the formula used.

🧭 How to Use

1. Example 1 – Cv → Flow

   • Mode: Cv → Flow

   • Cv = 12.5

   • ΔP = 5 psi

   • SG = 1.0 (water)

   Formula:
   Q = Cv × √(ΔP / SG)
   Q = 12.5 × √(5 / 1.0)
   √5 ≈ 2.2361
   Q ≈ 12.5 × 2.2361 ≈ 27.95 gpm

   You should see:

   • Valve Cv: 12.500

   • Pressure Drop: 5.000 psi

   • Specific Gravity: 1.000

   • Calculated Flow Rate: 27.950 US gpm

   Example 2 – Flow → Cv

   • Mode: Flow → Cv

   • Q = 50 gpm

   • ΔP = 5 psi

   • SG = 1.0

   Formula:
   Cv = Q × √(SG / ΔP)
   Cv = 50 × √(1 / 5)
   √(1/5) ≈ 0.4472
   Cv ≈ 50 × 0.4472 ≈ 22.36

   You should see:

   • Flow Rate: 50.000 US gpm

   • Pressure Drop: 5.000 psi

   • Specific Gravity: 1.000

   • Required Valve Cv: 22.360

Example

If this Control Valve Cv to Flow Converter helped you, explore more of our useful instrumentation tools:

• Loop Power & Voltage Drop Calculator

• 4–20 mA to Engineering Units Converter

• Control Valve Sizing Estimator

• PID Tuning Calculator

• RTD & Thermocouple Simulator

• Pressure/Flow/Level Converter

• Signal Splitter or Isolator Load Calculator

• Pressure Transmitter Range & Scaling Calculator

⭐ Next Steps

👉 Check out our practical eBooks and online courses designed for technicians, maintenance engineers, and students.

Looking for recommended hardware like signal isolators, splitters, loop indicators, and transmitters?

👉 Explore top-rated Control Valve eBooks on Amazon (Click here).

Stay tuned for more tools to make your instrumentation work faster, easier, and error-free!

Want to build deeper skills in industrial instrumentation?

FAQ

Q1. What is Cv in a control valve?

Cv is the valve’s flow coefficient, defined as the flow rate in US gpm of water at 60°F that produces a 1 psi pressure drop across the valve at a given opening.

Q2. Can I use this calculator for gases or steam?

This calculator is intended for liquid service only, using the standard liquid Cv formula. Gas and steam sizing require additional correction factors and equations.

Q3. What is Specific Gravity (SG)?

Specific gravity is the ratio of the fluid’s density to water. Water has SG ≈ 1.0. A lighter hydrocarbon might have SG ≈ 0.7–0.8.

Q4. Why is ΔP important in Cv calculations?

The pressure drop across the valve strongly affects flow capacity. Higher ΔP allows more flow through a given Cv, and lower ΔP reduces flow.