1. What is a CV Flow Rate Calculator?

Definition: This calculator determines the flow rate through a valve using the valve coefficient (C_v), pressure drop, and fluid specific gravity.

Purpose: It helps engineers and technicians size valves and predict flow rates in fluid systems.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( Q \) — Flow rate (gallons per minute, GPM)
• \( C_v \) — Valve coefficient (dimensionless)
• \( \Delta P \) — Pressure drop across the valve (psi)
• \( SG \) — Specific gravity of fluid (dimensionless, 1 for water)

Explanation: The flow rate is proportional to the valve coefficient and the square root of the pressure drop to specific gravity ratio.

3. Importance of CV Flow Rate Calculation

Details: Accurate flow rate prediction ensures proper valve selection, system performance, and avoids issues like cavitation or undersized piping.

4. Using the Calculator

Tips: Enter the valve C_v (from manufacturer specs), pressure drop across the valve, and fluid specific gravity (default 1 for water).

5. Frequently Asked Questions (FAQ)

Q1: What is the valve coefficient (C_v)?
A: C_v is the flow capacity of a valve, defined as the flow in GPM of 60°F water that produces 1 psi pressure drop.

Q2: How do I find the C_v for my valve?
A: Check manufacturer documentation or valve nameplate - it's typically provided for all control valves.

Q3: What's a typical pressure drop for valve sizing?
A: Common design practice uses 5-10 psi for control valves, but depends on system requirements.

Q4: When would I change the specific gravity?
A: For fluids other than water - SG is the ratio of fluid density to water density at 60°F.

Q5: Does this formula work for gases?
A: No, gas flow calculations require different formulas accounting for compressibility and temperature.