Water Valve CV Diagram

Overview

Engineering reference data for Water Valve CV Diagram in water systems.

Key Formulas

Hydrostatic Pressure

$P = \rho g h$

Pressure due to water column.

Flow Rate

$Q = A v$

Area × velocity.

Variables

Symbol	Description	Unit
$P$	Pressure	Pa
$Q$	Flow rate	m³/s
$h$	Head/depth	m

Practical Example

Based on the diagram provided, here is a worked example:

Given:

• Water Flow ($Q$): 6 GPM
• Pressure Drop ($\Delta P$): 10 PSI
• Fluid: Water (Specific Gravity, $SG = 1$)

Using the Diagram: Locate 6 GPM on the horizontal axis and move vertically to the line for a 10 PSI pressure drop. The intersection gives the required flow coefficient.

Result: The estimated Flow Coefficient $C_v$ is approximately *2.

Core Calculation Formula

While the diagram provides a visual solution, the underlying formula for calculating the flow coefficient is:

$$C_v = Q \times \sqrt{\frac{SG}{\Delta P}}$$

For water ($SG=1$), this simplifies to:

$$C_v = \frac{Q}{\sqrt{\Delta P}}$$

Where:

• $C_v$ is the Flow Coefficient (dimensionless)
• $Q$ is the volumetric flow rate (GPM)
• $\Delta P$ is the pressure drop across the valve (PSI)

References

• Original Source