1. What Is GPM Flow Rate?

Definition: GPM (Gallons Per Minute) is a unit of measurement for the flow rate of liquids, particularly water, through a pipe or channel.

Purpose: This calculator helps determine the volume of water flowing through a system each minute, which is crucial for plumbing, irrigation, and hydraulic system design.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( Q \) — Flow rate (gallons per minute)
• \( V \) — Velocity of water (feet per second)
• \( A \) — Cross-sectional area of pipe (square feet)
• 448.83 — Conversion factor (cubic feet to gallons and seconds to minutes)

Explanation: The formula converts the basic flow measurement (velocity × area) from cubic feet per second to gallons per minute.

3. Importance of GPM Calculation

Details: Accurate GPM calculations ensure proper system sizing, adequate water supply, and efficient operation of water-dependent systems.

4. Using the Calculator

Tips: Enter the water velocity in feet per second and the pipe's cross-sectional area in square feet. Both values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: How do I measure water velocity?
A: Velocity can be measured with flow meters or calculated from pressure differentials using Bernoulli's equation.

Q2: What's a typical GPM for household plumbing?
A: Standard fixtures require 2-5 GPM, while whole-house systems may need 6-12 GPM depending on size.

Q3: How do I calculate pipe cross-sectional area?
A: For circular pipes: \( A = \pi \times r^2 \) where r is the radius in feet.

Q4: Why is the conversion factor 448.83?
A: It combines 7.48052 (gallons per cubic foot) and 60 (seconds per minute): 7.48052 × 60 = 448.8312.

Q5: Does this work for other liquids?
A: Yes, but the conversion factor changes based on the liquid's density (use specific gravity for adjustments).