1. What is Centrifugal Pump Capacity?

Definition: This calculator determines the flow rate (capacity) of a centrifugal pump based on its horsepower, efficiency, total head, and fluid density.

Purpose: It helps engineers and technicians size pumps and verify their performance for various fluid transfer applications.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( Q \) — Pump capacity (gallons per minute, GPM)
• \( HP \) — Horsepower input to the pump
• \( \eta \) — Pump efficiency factor (0-1)
• \( H \) — Total dynamic head (feet)
• \( \rho \) — Fluid density (pounds per gallon)

Explanation: The formula relates the power input to the pump with the work done to move fluid against head and density.

3. Importance of Pump Capacity Calculation

Details: Proper pump sizing ensures efficient operation, prevents cavitation, and matches system requirements for flow and pressure.

4. Using the Calculator

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

5. Frequently Asked Questions (FAQ)

Q1: What is the constant 3960 in the formula?
A: This is a conversion factor that relates horsepower, flow rate, and head (1 HP = 3960 GPM·ft·lb/gal).

Q2: What's a typical efficiency factor for pumps?
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 dynamic 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 divided by 7.48 (gallons per cubic foot).

Q5: Does this account for system curve variations?
A: No, this calculates theoretical capacity. Actual flow depends on the system curve intersection with the pump curve.