1. What is Fire Pump Flow Rate Calculation?

Definition: This calculator determines the flow rate (in gallons per minute) that a fire pump can deliver based on its horsepower, efficiency, total head, and fluid density.

Purpose: Essential for fire protection system design to ensure adequate water supply for firefighting operations.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( Q \) — Flow rate (gallons per minute, GPM)
• \( HP \) — Pump horsepower
• \( \eta \) — Pump efficiency (0-1)
• \( H \) — Total dynamic head (feet)
• \( \rho \) — Fluid density (pounds per gallon)

Explanation: The formula relates pump power to flow rate by accounting for the energy required to move fluid against system head and density.

3. Importance of Fire Pump Calculations

Details: Proper flow rate calculation ensures fire pumps meet NFPA requirements and can deliver adequate water pressure and volume during emergencies.

4. Using the Calculator

Tips: Enter pump horsepower, efficiency (default 0.75), total head in feet, and fluid density (default 8.34 lb/gal for water). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is the constant 3960 in the formula?
A: This is a conversion factor that relates horsepower, flow rate, head, and specific gravity in consistent units.

Q2: What's a typical efficiency for fire pumps?
A: Most fire pumps operate between 70-85% efficiency (0.7-0.85).

Q3: How do I determine total dynamic head?
A: It's the sum of static head, friction losses, and pressure requirements at the discharge point.

Q4: When would fluid density change?
A: When pumping fluids other than water (e.g., foam solutions) or at different temperatures.

Q5: Does this account for net positive suction head?
A: No, NPSH calculations should be performed separately to ensure proper pump operation.