1. What is Valve Coefficient (Cv)?

The valve coefficient (Cv) is a number that represents the flow capacity of a valve. It's defined as the number of gallons per minute (gpm) 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 valve coefficient formula:

Where:

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

Explanation: The formula calculates how much fluid will flow through a valve given 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. It helps engineers select the right valve for specific flow requirements.

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 range for valves?
A: Cv values range from less than 1 for small valves to over 1000 for large valves, depending on valve type and size.

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

Q3: Can this formula be used for gases?
A: No, this formula is for liquids. Gas flow calculations require different formulas accounting for compressibility.

Q4: What's the relationship between Cv and Kv?
A: Kv is the metric equivalent of Cv. 1 Cv ≈ 1.156 Kv. Kv is defined using m³/h and bar.

Q5: Why is Cv important in valve selection?
A: Proper Cv ensures the valve can handle required flow rates without excessive pressure drop or cavitation.