1. What is a Valve Flow Rate 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 proportional to the valve's flow coefficient and the square root of the pressure drop to specific gravity ratio.

3. Importance of Flow Rate Calculation

Details: Accurate flow rate prediction ensures proper valve selection, system performance, and prevents issues like cavitation or insufficient flow.

4. Using the Calculator

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

5. Frequently Asked Questions (FAQ)

Q1: What is a typical C_v value?
A: C_v varies by valve size and type - from 1-5 for small valves to over 1000 for large valves.

Q2: How do I find the pressure drop?
A: Measure upstream and downstream pressures or calculate from system characteristics.

Q3: What's specific gravity for common fluids?
A: Water=1.0, Gasoline=0.7-0.8, Diesel=0.82-0.95, SAE 30 Oil=0.89.

Q4: Does this work for gases?
A: No, this formula is for liquids. Gas flow requires different calculations.

Q5: What if my flow is in other units?
A: Convert to GPM first or use appropriate C_v for your units (C_v definitions vary by region).