1. What is the Pump Flow Rate Formula?

Definition: This calculator determines the flow rate of a pump in gallons per minute (GPM) based on horsepower, efficiency, 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 dynamic head (feet)
• \( \rho \) — Fluid density (pounds per gallon, lb/gal)

Explanation: The formula relates the power input (HP) to the hydraulic power output, accounting for pump efficiency and the work needed to move the fluid against head and density.

3. Importance of Pump Flow Rate Calculation

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

4. Using the Calculator

Tips: Enter the pump horsepower (HP), efficiency (default 0.8), 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, head, and specific gravity in consistent units.

Q2: What's a typical pump efficiency value?
A: Centrifugal pumps typically range from 40-85% efficiency (0.4-0.85), with 0.8 being a common default for many applications.

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 7.4805 to convert from lb/ft³ to lb/gal.

Q5: Can this formula be used for all pump types?
A: This is most accurate for centrifugal pumps. Positive displacement pumps require different calculations.