Valve Flow Coefficient Cv / Kv

on . Posted in Fluid Dynamics

Valve flow coefficient, abbreviated as Cv (in the United States) or Kv (in Europe), is a numerical value used to quantify the flow capacity of a valve or other fluid control device.  It is a parameter in fluid dynamics and is used to describe how well a valve can control the flow of a fluid, typically a liquid or gas.  The Cv/Kv value is important in various industries, including manufacturing, chemical processing, HVAC, and more.

Valve manufacturers provide Cv or Kv values for their products to help engineers and users select the appropriate valve for a specific application, ensuring that the valve can provide the desired flow rate and control characteristics.  This information is essential for designing systems where precise control of fluid flow is required, such as in regulating the flow of water, steam, gases, or other fluids in various industrial processes.

 Key Points about Valve Cv / Kv

  • A higher Cv or Kv value indicates a valve with a larger flow capacity, it can handle a higher flow rate with a given pressure drop.
  • A lower Cv or Kv value indicates a valve with a smaller flow capacity.

 conversion between Cv / Kv

  • \( C_v  =  1.16 \; K_v   \)
  • \( K_v  =  0.862 \; C_v   \)


Valve Flow Coefficient CV / flow Factor KV Formula

\( C_v \;=\;   Q  \sqrt{ SG \;/\; \Delta P } \)     (Valve Flow Coefficient Cv)

\( Q \;=\;   \sqrt{ C_v^2 \; \Delta P \;/\; SQ } \)

\( SG \;=\; C_v^2 \; \Delta P \;/\; Q^2 \)

\( \Delta P \;=\; SG \; C_v^2 \;/\; Q^2 \)

\( K_v \;=\;   Q  \sqrt{ SG \;/\; \Delta P } \)     (Valve Flow Factor Kv)

Solve for Cv

valve flow rate, Q
specific gravity, SG
valve pressure differential, DP

Solve for Q

valve flow coefficient, Cv
valve pressure differential, DP
specific gravity, SG

Solve for SG

valve flow coefficient, Cv
valve pressure differential, DP
valve flow rate, Q

Solve for DP

specific gravity, SG
valve flow coefficient, Cv
valve flow rate, Q
Symbol English Metric
\( C_v \) = valve flow coefficient (US units) \( gpm \) -
\( K_v \) = valve flow factor (SI units) - \(m^3 \;/\; h\)
\( Q \) = valve flow rate \( gpm \) \(m^3 \;/\; h\)
\( SG \) = specific gravity of liquid (water at 60°F = 1.0000) \( dimensionless \)
\( \Delta P \) = valve pressure differential \(lbf \;/\;in^2\) \(N \;/\; m^2\)


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Tags: Coefficient Flow Valve Sizing