1. What is Pump Sizing?

Pump sizing is the process of determining the appropriate pump power (horsepower) required to move a fluid at a specified flow rate against a given head, accounting for fluid properties and pump efficiency.

2. How Does the Calculator Work?

The calculator uses the pump power formula:

Where:

• \( Q \) — Flow rate (gallons per minute, GPM)
• \( H \) — Total dynamic head (feet, ft)
• \( SG \) — Specific gravity (dimensionless, 1 for water)
• \( \eta \) — Pump efficiency (decimal, 0-1)
• 3960 — Conversion factor (ft·lb/min per HP)

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

3. Importance of Proper Pump Sizing

Details: Correct pump sizing ensures energy efficiency, prevents cavitation, extends equipment life, and ensures the system meets performance requirements.

4. Using the Calculator

Tips:

• For water systems, specific gravity is 1.0
• Typical pump efficiencies range from 0.5 to 0.85
• Include safety factors in final pump selection
• Consider NPSH requirements for cavitation prevention

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between BHP and WHP?
A: Brake horsepower (BHP) is power at the pump shaft, while water horsepower (WHP) is the actual hydraulic power delivered to the fluid.

Q2: How do I account for system losses?
A: Include all friction losses in your total head calculation (pipe friction, fittings, valves, etc.).

Q3: What's a typical pump efficiency?
A: Centrifugal pumps typically range from 50-85% efficiency depending on size and design.

Q4: How does viscosity affect pump sizing?
A: High viscosity fluids require more power and may need positive displacement pumps.

Q5: Should I add a safety factor?
A: Yes, typically 10-20% additional capacity is recommended for system variations and future needs.