1. What is a Fire Pump Horsepower Calculator?

Definition: This calculator determines the required horsepower for a fire pump based on flow rate, total head, and pump efficiency.

Purpose: It helps fire protection engineers and designers properly size fire pumps for building protection systems.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( HP \) — Pump horsepower
• \( Q \) — Flow rate (gallons per minute)
• \( H \) — Total head (feet)
• \( \eta \) — Pump efficiency (0-1)
• 8.34 — Weight of water in pounds per gallon
• 3960 — Conversion factor (foot-pounds per minute to horsepower)

Explanation: The formula calculates the power needed to move water at a specified flow rate against the system's total head pressure.

3. Importance of Proper Pump Sizing

Details: Correct horsepower calculation ensures adequate fire protection, prevents pump overload, and optimizes energy efficiency.

4. Using the Calculator

Tips: Enter the flow rate in GPM, total head in feet, and pump efficiency (default 0.85). All values must be > 0, and efficiency between 0 and 1.

5. Frequently Asked Questions (FAQ)

Q1: What is total head in pump calculations?
A: Total head is the sum of static head, friction loss, and pressure requirements in the system.

Q2: What's a typical pump efficiency value?
A: Most fire pumps operate at 75-85% efficiency (0.75-0.85), but check manufacturer specifications.

Q3: Why is 8.34 used in the formula?
A: This represents the weight of one gallon of water in pounds at standard conditions.

Q4: Should I round up the calculated horsepower?
A: Yes, always select the next available standard pump size to ensure adequate capacity.

Q5: Does this include motor efficiency?
A: No, this calculates pump horsepower. Motor selection should account for additional efficiency factors.