1. What is Fire Pump Horsepower Calculation?

The fire pump horsepower calculation determines the required power for a pump to move a specific flow rate of liquid against a given head pressure, accounting for fluid properties and pump efficiency.

2. How Does the Calculator Work?

The calculator uses the pump horsepower equation:

Where:

• \( Q \) — Flow rate in gallons per minute (GPM)
• \( H \) — Total dynamic head in feet
• \( SG \) — Specific gravity of fluid (1.0 for water)
• \( \eta \) — Pump efficiency (0-1 decimal)
• 3960 — Conversion factor (foot-pounds per minute per horsepower)

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

3. Importance of Proper Pump Sizing

Details: Correct pump sizing ensures adequate fire protection while avoiding energy waste. Undersized pumps fail to deliver required flow/pressure, while oversized pumps increase costs and may cause system damage.

4. Using the Calculator

Tips: Enter flow rate in GPM, head in feet, specific gravity (1.0 for water), and pump efficiency (typically 0.65-0.85 for centrifugal pumps). All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is typical pump efficiency?
A: Centrifugal pumps typically have 65-85% efficiency. Consult manufacturer data for specific pumps.

Q2: How do I determine total dynamic head?
A: TDH includes static head, friction losses, and pressure requirements. Professional hydraulic calculations are recommended.

Q3: Should I add a safety factor?
A: Yes, most applications add 10-20% safety margin to calculated horsepower for operational variations.

Q4: What about motor sizing?
A: Motors are typically sized to the next standard horsepower above the calculated pump requirement.

Q5: Does this work for all pump types?
A: This equation is primarily for centrifugal pumps. Positive displacement pumps require different calculations.