1. What is Pump Horsepower?

Pump horsepower (HP) is the power required to move a fluid at a specified flow rate against a given head pressure, accounting for the pump's efficiency. It's a critical parameter for selecting and sizing pumps in water systems.

2. How Does the Calculator Work?

The calculator uses the standard pump horsepower formula:

Where:

• \( Q \) — Flow rate in gallons per minute (GPM)
• \( H \) — Total head in feet
• \( SG \) — Specific gravity of fluid (1.0 for water)
• \( \eta \) — Pump efficiency (0-1 decimal)
• 3960 — Conversion factor (foot-pounds per minute to HP)

Explanation: The formula calculates the theoretical power required to move the fluid, then divides by the pump's efficiency to get actual required horsepower.

3. Importance of Pump HP Calculation

Details: Proper horsepower calculation ensures you select a pump that can handle your flow and head requirements without being oversized (wasting energy) or undersized (failing to meet demand).

4. Using the Calculator

Tips:

• For water systems, use SG = 1.0
• Typical pump efficiencies range from 0.5 to 0.9 (50-90%)
• Include all head losses (static head + friction loss)
• Always round up to the nearest standard motor size

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between brake HP and water HP?
A: Water HP is the theoretical power needed to move the fluid. Brake HP includes pump inefficiencies (what the motor must actually deliver).

Q2: How do I account for motor efficiency?
A: Divide the calculated HP by the motor efficiency (typically 0.9-0.95) to get required input power.

Q3: What's a typical pump efficiency?
A: Centrifugal pumps typically range from 50-85% efficient, with higher efficiencies at design flow points.

Q4: How do I convert to kW?
A: Multiply HP by 0.746 to get kilowatts.

Q5: What if I have viscosity other than water?
A: The calculator works for Newtonian fluids with known SG. For viscous fluids, additional corrections are needed.