1. What is a Valve Cv Calculator?

Definition: This calculator determines the flow coefficient (Cv) for a valve based on flow rate, pressure drop, and fluid specific gravity.

Purpose: It helps engineers and technicians select properly sized valves for fluid control systems.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( C_v \) — Flow coefficient (dimensionless)
• \( Q \) — Flow rate (gallons per minute)
• \( \Delta P \) — Pressure drop across valve (psi)
• \( SG \) — Specific gravity of fluid (water = 1.0)

Explanation: The Cv represents the flow in GPM of water at 60°F that will pass through the valve with a 1 psi pressure drop.

3. Importance of Cv Calculation

Details: Proper Cv calculation ensures optimal valve sizing for desired flow characteristics and system performance.

4. Using the Calculator

Tips: Enter the flow rate in GPM, pressure drop in psi, and fluid specific gravity (default 1.0 for water). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What does Cv represent?
A: Cv is a measure of a valve's flow capacity - the higher the Cv, the more flow the valve can pass at a given pressure drop.

Q2: What's a typical Cv range?
A: Cv values range from <1 for small valves to >1000 for large valves, depending on valve type and size.

Q3: When would I need to calculate Cv?
A: When selecting a valve for a specific application or verifying an existing valve's capacity.

Q4: How does specific gravity affect Cv?
A: Higher SG fluids require more pressure to achieve the same flow, resulting in lower Cv values.

Q5: Can this be used for gases?
A: This formula is primarily for liquids. Gas flow calculations require additional factors.