1. What is Flow Rate from Valve CV Calculator?

Definition: This calculator determines the flow rate through a valve based on its flow 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 flow coefficient (dimensionless)
• \( \Delta P \) — Pressure drop across valve (psi)
• \( SG \) — Specific gravity of fluid (dimensionless)

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

3. Importance of Valve Flow Calculation

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

4. Using the Calculator

Tips: Enter the valve C_v (from manufacturer specs), pressure drop across valve, and fluid specific gravity (1.0 for water). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is valve C_v?
A: The flow coefficient representing gallons per minute of 60°F water that will flow through the valve with a 1 psi pressure drop.

Q2: Why does specific gravity matter?
A: Heavier fluids (SG > 1) will flow slower than water at the same pressure drop, while lighter fluids (SG < 1) will flow faster.

Q3: Is this formula valid for all fluids?
A: Primarily for non-compressible liquids. For gases or steam, different formulas accounting for compressibility are needed.

Q4: What's a typical C_v value?
A: Varies by valve size and type. A 1" ball valve might have C_v ≈ 25, while a 2" might be ≈ 100.

Q5: Does this account for viscosity effects?
A: No, this formula assumes Newtonian fluids with viscosity similar to water. For viscous fluids, correction factors are needed.