CV Flow Calculator

The CV Flow Calculator helps determine the flow coefficient (CV) of a valve, which represents the valve’s capacity to allow fluid flow at a given pressure drop. It is a crucial tool for engineers, technicians, and fluid system designers to ensure optimal valve selection in hydraulic, pneumatic, and industrial piping systems.

The CV value indicates how much fluid (typically measured in gallons per minute (GPM)) will flow through a valve with a 1 psi pressure drop. A higher CV value means the valve allows more fluid to pass through, making it essential for flow regulation and system efficiency.

Formula of CV Flow Calculator

The basic CV flow formula is:

Where:

• CV = Flow coefficient.
• Q = Flow rate (in gallons per minute, GPM).
• ΔP = Pressure drop across the valve (in psi).

For Fluids Other Than Water:

If the fluid has a different specific gravity (SG) than water, the formula adjusts to:

CV = (Q × √SG) / √(ΔP)

Where:

• SG = Specific gravity of the fluid (ratio of the fluid's density to water’s density at 60°F).

This equation allows for accurate flow coefficient calculations across different fluids and conditions.

General CV Flow Reference Table

The table below provides approximate CV values for different flow rates and pressure drops:

Flow Rate (GPM)	Pressure Drop (ΔP) (psi)	CV for Water	CV for SG = 1.5
5	2	3.54	4.33
10	5	4.47	5.47
20	8	7.07	8.65
50	10	15.81	19.35
100	15	25.82	31.62

This table helps in quickly estimating the required CV values for various conditions.

Example of CV Flow Calculator

A valve system needs to handle:

• Flow rate (Q) = 20 GPM
• Pressure drop (ΔP) = 8 psi
• Fluid specific gravity (SG) = 1.2

Using the formula:

CV = (20 × √1.2) / √8
CV = (20 × 1.095) / 2.828 = 7.75

This means the required CV rating of the valve should be at least 7.75 to ensure efficient flow management.

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