1. What is the Cv Flow Equation?

The Cv (Flow Coefficient) equation calculates the flow capacity of a valve or other flow restriction. It represents the flow rate of water in gallons per minute (gpm) at 60°F that will pass through a valve with a pressure drop of 1 psi.

2. How Does the Calculator Work?

The calculator uses the Cv flow equation:

Where:

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

Explanation: The equation relates the flow rate through a valve to the pressure drop and fluid properties.

3. Importance of Cv Calculation

Details: Cv is crucial for valve sizing, system design, and ensuring proper flow control in piping 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 range from less than 1 for small valves to over 1000 for large valves, depending on valve size and type.

Q2: How does specific gravity affect Cv?
A: Higher specific gravity fluids (more dense) will have lower flow rates for the same pressure drop, resulting in a lower calculated Cv.

Q3: Can this be used for gases?
A: This simple equation is primarily for liquids. Gas flow calculations require additional factors like temperature and compressibility.

Q4: What's the difference between Cv and Kv?
A: Kv is the metric equivalent of Cv, where flow is in m³/h and pressure is in bar. Kv = 0.865 × Cv.

Q5: How accurate is this calculation?
A: It provides a good estimate for turbulent flow conditions. For precise applications, consult valve manufacturer's data.