1. What is Pump Horsepower Calculation?

The pump horsepower calculation determines the power required to move a fluid at a specified flow rate 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 (ft)
• \( SG \) — Specific gravity of fluid (1 for water)
• \( \eta \) — Pump efficiency (decimal, 0-1)
• 3960 — Conversion factor (ft-lb/min per HP)

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 Pump Sizing

Details: Proper pump sizing ensures efficient operation, prevents motor overload, and matches system requirements. Oversized pumps waste energy while undersized pumps can't meet demand.

4. Using the Calculator

Tips: Enter flow rate in GPM, head in feet, specific gravity (1 for water), and pump efficiency as decimal (typically 0.7-0.9). All values must be positive.

5. Frequently Asked Questions (FAQ)

Q1: What is typical pump efficiency?
A: Centrifugal pumps typically range from 50-85% efficiency. Positive displacement pumps can reach 90% efficiency.

Q2: How do I determine total dynamic head?
A: TDH = static head + friction head + pressure head. It includes elevation change, pipe friction losses, and system pressure requirements.

Q3: What's the difference between water HP and brake HP?
A: Water HP is theoretical power to move fluid. Brake HP includes pump efficiency (Water HP / η). This calculator gives brake HP.

Q4: When should I add a safety factor?
A: Add 10-20% safety factor to calculated HP for system uncertainties, especially if operating near pump curve limits.

Q5: Can I use this for viscous fluids?
A: This basic calculation works for water-like fluids. For viscous fluids, correction factors are needed for both flow and efficiency.