1. What is Flow Coefficient Cv?

The Flow Coefficient (Cv) is a dimensionless number that represents the flow capacity of a valve or other flow component. It's defined as the number of US gallons per minute of water at 60°F that will flow through a valve with a pressure drop of 1 psi.

2. How Does the Calculator Work?

The calculator uses the Flow Coefficient formula:

Where:

• \( C_v \) — Flow coefficient (dimensionless)
• \( Q \) — Flow rate (gpm)
• \( SG \) — Specific gravity (dimensionless)
• \( \Delta P \) — Pressure drop (psi)

Explanation: The equation shows that Cv is directly proportional to flow rate and the square root of the ratio of specific gravity to pressure drop.

3. Importance of Cv Calculation

Details: The Cv value is crucial for valve sizing and selection, ensuring proper flow control and system performance in fluid handling systems.

4. Using the Calculator

Tips: Enter flow rate in gpm, specific gravity (1.0 for water), and pressure drop in psi. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical Cv value range?
A: Cv values vary widely depending on valve size and type, from less than 1 for small valves to over 1000 for large valves.

Q2: How does specific gravity affect Cv?
A: Higher specific gravity fluids require larger Cv values to achieve the same flow rate at a given pressure drop.

Q3: Can Cv be used for gases?
A: While primarily for liquids, modified versions of the Cv equation exist for gas flow calculations.

Q4: What's the difference between Cv and Kv?
A: Kv is the metric equivalent, using m³/h and bar. Conversion: Cv = 1.156 Kv.

Q5: How accurate is the Cv calculation?
A: It provides a theoretical value; actual performance may vary based on valve design, installation, and flow conditions.