1. What is a GPM to Pipe Size Calculator?

Definition: This calculator determines the required pipe diameter based on flow rate (in gallons per minute) and fluid velocity.

Purpose: It helps engineers, plumbers, and irrigation specialists select the proper pipe size for fluid transport systems.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( D \) — Pipe diameter (feet)
• \( Q \) — Flow rate (gallons per minute)
• \( V \) — Fluid velocity (feet per second)
• \( \pi \) — Pi (approximately 3.1416)
• 7.481 — Conversion factor (gallons per cubic foot)

Explanation: The formula calculates the pipe diameter needed to maintain a specific flow rate at a given velocity.

3. Importance of Proper Pipe Sizing

Details: Correct pipe sizing ensures efficient flow, prevents excessive pressure loss, avoids water hammer, and maintains system performance.

4. Using the Calculator

Tips: Enter the flow rate in GPM and desired velocity (default 5 ft/s for water). Typical velocities: 2-5 ft/s for suction, 5-10 ft/s for discharge.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical velocity for water pipes?
A: For water, 4-6 ft/s is common. Higher velocities increase friction loss and noise.

Q2: How do I convert the result to inches?
A: Multiply the result by 12 (1 ft = 12 inches). For example, 0.25 ft = 3 inches.

Q3: What velocity should I use for viscous fluids?
A: Use lower velocities (1-3 ft/s) for viscous fluids to reduce friction losses.

Q4: Does this account for pipe material roughness?
A: No, this calculates theoretical diameter. For precise sizing, consider material and length using Darcy-Weisbach equation.

Q5: What's the maximum recommended velocity?
A: Generally 10 ft/s for water, but consult specific standards for your application.