1. What is the Pump Flow Rate Equation?

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

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

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( Q \) — Flow rate (gallons per minute)
• \( HP \) — Horsepower input to the pump
• \( \eta \) — Pump efficiency (0-1, where 1 is 100% efficient)
• \( H \) — Total dynamic head (feet)

Explanation: The formula relates the mechanical power input to the hydraulic power output, accounting for the pump's efficiency.

3. Importance of Pump Flow Rate Calculation

Details: Proper flow rate estimation ensures adequate system performance, energy efficiency, and prevents pump overload or underutilization.

4. Using the Calculator

Tips: Enter the pump horsepower (HP), efficiency (default 0.85 for 85% efficiency), and total head in feet. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is the constant 3960 in the equation?
A: This is a conversion factor that relates horsepower to foot-pounds per minute (1 HP = 33,000 ft-lb/min, and 33,000/8.34 ≈ 3960).

Q2: What's a typical pump efficiency value?
A: Most pumps operate between 50-85% efficiency, with centrifugal pumps typically in the 70-85% range.

Q3: How do I determine total dynamic head?
A: Total head includes static head (vertical distance) plus friction losses in the piping system.

Q4: Can this be used for any pump type?
A: This is primarily for centrifugal pumps. Positive displacement pumps require different calculations.

Q5: What if my flow rate seems too high or low?
A: Double-check your head and efficiency values. Consider that actual performance may vary from theoretical calculations.