1. What is Pump Flow Rate?

Definition: This calculator determines the flow rate of a pump in gallons per minute (GPM) based on horsepower, efficiency, total head, and fluid density.

Purpose: It helps engineers and technicians size pumps and understand their performance characteristics in fluid systems.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( Q \) — Flow rate (gallons per minute, GPM)
• \( HP \) — Horsepower (HP)
• \( \eta \) — Pump efficiency (dimensionless, 0-1)
• \( H \) — Total head (feet)
• \( \rho \) — Fluid density (pounds per gallon, lb/gal)

Explanation: The formula relates the power input (HP) to the hydraulic power output (flow × head × density), accounting for pump efficiency.

3. Importance of Pump Flow Rate Calculation

Details: Accurate flow rate calculation ensures proper pump selection, system design, and energy efficiency in fluid transport systems.

4. Using the Calculator

Tips: Enter the pump horsepower (HP), efficiency (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: It's a conversion factor that equates horsepower to foot-pounds per minute (1 HP = 3960 ft-lb/min).

Q2: What's a typical pump efficiency value?
A: Centrifugal pumps typically range from 60-85% efficiency (0.6-0.85), while positive displacement pumps can reach 90% (0.9).

Q3: How do I determine total head?
A: Total head is the sum of static head, friction head, and pressure head in the system.

Q4: What density should I use for other fluids?
A: Use 8.34 lb/gal for water. For other fluids, multiply by specific gravity (e.g., 8.34 × 0.79 = 6.59 lb/gal for ethanol).

Q5: Can this calculate required horsepower for a desired flow?
A: Yes, rearrange the formula: \( HP = \frac{Q \times H \times \rho}{3960 \times \eta} \)