1. What is the Water Pump Flow Rate Formula?

Definition: This calculator estimates the flow rate of a water pump based on its horsepower, efficiency, and total head.

Purpose: It helps engineers, plumbers, and irrigation specialists determine the expected performance of water pumps.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( Q \) — Flow rate (gallons per minute, GPM)
• \( HP \) — Pump horsepower
• \( \eta \) — Pump efficiency (0-1)
• \( H \) — Total head (feet)

Explanation: The formula converts mechanical power to hydraulic power, accounting for pump efficiency and the work needed to lift water against gravity.

3. Importance of Flow Rate Calculation

Details: Proper flow rate estimation ensures adequate water supply, correct pump sizing, and energy-efficient system design.

4. Using the Calculator

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

5. Frequently Asked Questions (FAQ)

Q1: What is pump efficiency?
A: Pump efficiency (η) is the ratio of hydraulic power delivered to the mechanical power input, typically 0.7-0.9 for good pumps.

Q2: How do I determine total head?
A: Total head includes vertical lift plus friction losses in pipes. Use our Head Loss Calculator for accurate measurements.

Q3: Why is 3960 in the formula?
A: This is a conversion factor (1 HP = 3960 ft-lb/min) that relates horsepower to hydraulic power.

Q4: What's a typical efficiency value?
A: Most centrifugal pumps operate at 70-85% efficiency (0.7-0.85), while positive displacement pumps can reach 90% (0.9).

Q5: Can I use this for other liquids?
A: The formula works for water. For other liquids, adjust the 8.34 factor (water's weight in lb/gal) to match your liquid's density.