1. What is Fire Pump Horsepower?

Fire pump horsepower calculation determines the power required to move water at a specific flow rate against a certain head pressure, accounting for pump efficiency and fluid properties.

2. How Does the Calculator Work?

The calculator uses the fire pump horsepower equation:

Where:

• \( Q \) — Flow rate in gallons per minute (GPM)
• \( H \) — Total head in feet
• \( SG \) — Specific gravity of fluid (1.0 for water)
• \( \eta \) — Pump efficiency as decimal (0.0-1.0)
• 3960 — Conversion factor (ft-lb/min per HP)

Explanation: The equation calculates the theoretical power needed to move the fluid, then divides by pump efficiency to get actual required horsepower.

3. Importance of Proper Pump Sizing

Details: Correct horsepower calculation ensures the pump can deliver required flow and pressure while operating efficiently. Oversizing wastes energy, undersizing risks inadequate fire protection.

4. Using the Calculator

Tips: Enter flow rate in GPM, total head in feet, specific gravity (1.0 for water), and pump efficiency (typically 0.7-0.9 for centrifugal pumps). All values must be positive.

5. Frequently Asked Questions (FAQ)

Q1: What's typical efficiency for fire pumps?
A: Centrifugal fire pumps typically have 70-85% efficiency at their best efficiency point (BEP).

Q2: How does head relate to pressure?
A: Head (ft) = Pressure (psi) × 2.31 / SG. For water, 100 ft head ≈ 43.3 psi.

Q3: Should I add a safety factor?
A: Yes, typical practice adds 10-15% to calculated HP for safety margin and future needs.

Q4: What affects pump efficiency?
A: Pump design, size relative to load, wear, and operating point relative to BEP.

Q5: How does viscosity affect calculations?
A: High viscosity fluids require special corrections not accounted for in this basic formula.