1. What is the Pump Horsepower Formula?

Definition: This formula calculates the required horsepower for a pump based on flow rate, total 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 used is:

Where:

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

Explanation: The formula calculates the power needed to move a specific volume of fluid against a given head pressure, adjusted for pump efficiency.

3. Importance of Pump Horsepower Calculation

Details: Proper horsepower calculation ensures energy-efficient operation, prevents pump overload, and helps select the right motor size.

4. Using the Calculator

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

5. Frequently Asked Questions (FAQ)

Q1: What is the constant 3960 in the formula?
A: It's a conversion factor that combines various unit conversions to give horsepower directly.

Q2: What's a typical pump efficiency value?
A: Centrifugal pumps typically range from 0.7 to 0.9 (70-90% efficient), with 0.85 being a common default.

Q3: How do I determine total head?
A: Total head includes static head, friction losses, and pressure differences in the system.

Q4: What density should I use for other fluids?
A: For fluids other than water, use their specific weight (e.g., 6.6 lb/gal for gasoline, 9.3 lb/gal for seawater).

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