1. What is Pump Horsepower?

Pump horsepower is the power required to drive a pump to move fluid at a specified flow rate against a given head. It represents the mechanical energy input needed to overcome hydraulic losses and maintain fluid movement through the system.

2. How Does the Calculator Work?

The calculator uses the pump horsepower formula:

Where:

• \( HP \) — Pump horsepower
• \( Q \) — Flow rate in gallons per minute (GPM)
• \( H \) — Total head in feet (ft)
• \( SG \) — Specific gravity of the fluid
• \( \eta \) — Pump efficiency (decimal)
• 3960 — Conversion constant

Explanation: The formula calculates the theoretical power required to move fluid, then divides by pump efficiency to account for mechanical and hydraulic losses.

3. Importance of Pump Horsepower Calculation

Details: Accurate horsepower calculation is essential for proper pump selection, motor sizing, energy consumption estimation, and ensuring system reliability and efficiency.

4. Using the Calculator

Tips: Enter flow rate in GPM, head in feet, specific gravity (1.0 for water), and pump efficiency as a decimal (typically 0.5-0.9). All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between brake horsepower and water horsepower?
A: Water horsepower is the theoretical power to move fluid, while brake horsepower includes pump inefficiencies and is the actual power required at the pump shaft.

Q2: How do I determine pump efficiency?
A: Pump efficiency varies by type and size. Centrifugal pumps typically range from 50-85%, while positive displacement pumps can reach 90%. Consult manufacturer curves.

Q3: What is specific gravity and when does it matter?
A: Specific gravity is the fluid density relative to water. It significantly affects horsepower for dense fluids like chemicals, slurries, or oils.

Q4: Why is the constant 3960 used?
A: 3960 converts (GPM × ft × lb/gal) to horsepower, derived from the relationship: 1 HP = 550 ft-lb/s and 1 gallon of water = 8.34 lb.

Q5: How does viscosity affect horsepower?
A: Higher viscosity fluids require more power due to increased friction losses. For viscous fluids, consult pump performance curves or use correction factors.