Liquid Control Valve Cv Sizing

Calculate the flow coefficient (Cv) for liquid control valves per ISA/IEC 60534.

Liquid Control Valve Sizing Calculator Guide (PDF)

This calculator is used to size liquid control valves. The calculator determines the valve flow coefficient (Cv) required for a specified liquid flow rate and pressure drop. The calculator can handle non-flashing and flashing liquid flow. The calculation method is based on the International Electrotechnical Commission procedure described in the Emerson Control Valve Handbook.

The calculator can handle non-flashing, flashing and choked flow.

  1. Enter the mass flow rate of liquid the valve must pass
  2. Enter the pressures upstream and downstream of the valve
  3. Enter the fluid physical properties
  4. Enter the valve liquid pressure recovery factor
    • This can be obtained from valve manufacturer's literature
    • Typical values for globe valves range from 0.70 to 0.97
  5. Enter the piping geometry factor
  6. Click the "Calculate" button
  7. The calculator will determine the valve Cv
  8. The calculator will also determine if the flow is critical or not through the valve
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INPUTS
Liquid mass flow rate w
Upstream pressure P1
Downstream pressure P2
Fluid density ρ
Fluid vapour pressure Pv
Fluid critical pressure Pc
Valve liquid pressure recovery factor FL
Piping geometry factor FP
OUTPUTS
Liquid critical pressure ratio factor FF 0.9573
Maximum allowable sizing pressure drop ΔPmax 9.9809
Critical flow?   NO
Effective pressure drop ΔPeff 5.0
Valve flow coefficient Cv 0.518
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