1. What is a Fire Flow Rate Calculator?

Definition: This calculator determines the water flow rate through a fire nozzle or hose in gallons per minute (GPM) based on nozzle characteristics and pressure conditions.

Purpose: It helps firefighters and fire protection engineers calculate water flow for firefighting operations and system design.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( Q \) — Flow rate (gallons per minute, GPM)
• \( C_d \) — Discharge coefficient (dimensionless, typically 0.97 for nozzles)
• \( A \) — Nozzle area (square feet, ft²)
• \( \Delta P \) — Pressure difference (pounds per square inch, psi)
• \( \rho \) — Water density (pounds per cubic foot, lb/ft³)

Explanation: The formula calculates flow based on Bernoulli's principle, converting the result to GPM for practical use.

3. Importance of Fire Flow Rate Calculation

Details: Accurate flow rate calculation ensures proper water delivery for fire suppression, adequate system design, and effective firefighting strategies.

4. Using the Calculator

Tips: Enter the discharge coefficient (default 0.97), nozzle area in ft², pressure difference in psi, and water density (default 62.4 lb/ft³). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical discharge coefficient (C_d) for fire nozzles?
A: Most fire nozzles have C_d values between 0.95 and 0.99, with 0.97 being a common default.

Q2: How do I calculate nozzle area?
A: For circular nozzles, use \( A = \pi \times r^2 \) where r is the radius in feet.

Q3: Why is the density of water 62.4 lb/ft³?
A: This is the standard density of water at room temperature (68°F or 20°C).

Q4: What pressure difference should I use?
A: Use the nozzle pressure (typically 100 psi for fog nozzles, 50 psi for smooth bore nozzles).

Q5: What's the practical range for fire flow rates?
A: Typical handlines flow 95-250 GPM, while master streams can flow 350-1500 GPM.