1. What is a Fire Pump Flow Rate Calculator?

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

Purpose: It helps fire protection engineers and technicians properly size fire pumps and ensure adequate water supply for fire suppression systems.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

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

Explanation: The formula converts pump power into flow rate considering the energy required to lift the fluid against gravity and overcome system resistance.

3. Importance of Fire Pump Calculations

Details: Accurate flow rate calculation ensures fire pumps can deliver sufficient water pressure and volume to meet fire protection system demands.

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 combines unit conversions for horsepower, feet, and minutes.

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

Q3: How do I determine total head?
A: Total head includes static lift, friction loss, and pressure requirements - consult hydraulic calculations.

Q4: When would fluid density change?
A: Density changes with fluid type (water vs. foam solution) and temperature.

Q5: Does this account for NFPA requirements?
A: This calculates theoretical flow - actual pump selection must meet NFPA 20 requirements.