Control Valve Sizing Calculator – Cv Calculation

Cv vs Valve Opening Curve

📘 Control Valve Sizing Calculator – User Guide

• This calculator estimates control valve Cv based on ISA-75.01.01 / IEC 60534-2-1 standards for liquid and gas applications.
• Select Unit System (Metric / Imperial) and Fluid State (Liquid or Gas).
  The calculator automatically adjusts formulas and input requirements.
• Enter fluid properties such as specific gravity, vapor pressure, viscosity (for liquids), or molecular weight, compressibility, and heat ratio (for gases).
• Provide Minimum, Normal, and Maximum operating conditions:
  • Flow rate
    • Liquid → m³/h
    • Gas → kg/h
  • Inlet pressure (P1 – gauge)
  • Outlet pressure (P2 – gauge)
  • Temperature (required for gas)
• Gauge pressures are automatically converted to absolute pressure during calculation.
• Valve-specific factors (Fₗ for liquid, xₜ for gas) are used to check choked flow conditions.
• The calculator determines:
  • Required Cv for each case
  • Maximum Cv as recommended valve sizing Cv
• After entering the selected valve rated Cv, estimated valve openings are shown for:
  • Minimum
  • Normal
  • Maximum flow conditions
• Warnings appear if the valve is oversized, undersized, or operating near fully open or closed positions.
• A Cv vs Valve Opening characteristic curve is generated using the selected valve characteristic to visualize controllability.

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⚠️ Engineering Note

Disclaimer: This calculator is intended for learning and preliminary estimation only. While it follows standard industry methods, it uses simplified assumptions and the accuracy of results is not guaranteed. Final control valve sizing and selection must always be reviewed by a qualified engineer and verified using the valve manufacturer’s official sizing tools and data. Actual performance may vary due to factors such as fluid properties, process conditions, noise, or cavitation. By using this tool, the user accepts full responsibility for its application, and the website owner is not liable for any resulting issues or losses.