1. What is the Pump Power Formula?

Definition: This formula calculates the horsepower required for a pump based on flow rate, head, fluid density, and pump efficiency.

Purpose: It helps engineers and technicians properly size pumps for various fluid transfer applications.

2. How Does the Formula Work?

The formula is:

Where:

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

Explanation: The numerator represents the hydraulic power, while the denominator (3960) is a conversion factor to get horsepower when using these units.

3. Importance of Pump Power Calculation

Details: Accurate power calculation ensures proper pump selection, energy efficiency, and prevents motor overload.

4. Using the Calculator

Tips: Enter flow rate in GPM, head in feet, density in lb/gal (default 8.34 for water), and efficiency as decimal (default 0.85). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's the 3960 constant?
A: It's a unit conversion factor that converts (lb-ft/min) to horsepower (1 HP = 3960 lb-ft/min).

Q2: What's a typical pump efficiency?
A: Centrifugal pumps typically range from 0.7-0.9 (70-90%), while positive displacement pumps can reach 0.9-0.95.

Q3: How do I find total head (H)?
A: Total head is the sum of static head, friction head, and pressure head in the system.

Q4: When would density change?
A: Different fluids have different densities (e.g., gasoline ~6.0 lb/gal, brine ~8.5-9.0 lb/gal).

Q5: Should I add a safety factor?
A: Yes, it's common to add 10-20% to the calculated HP for safety margins and future needs.