1. What is a Pipe Size GPM Calculator?

Definition: This calculator determines the required pipe diameter based on flow rate (GPM) and desired fluid velocity.

Purpose: It helps engineers, plumbers, and designers select the appropriate pipe size for fluid 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 minimum pipe diameter needed to maintain the desired velocity for a given flow rate.

3. Importance of Pipe Sizing

Details: Proper pipe sizing ensures efficient flow, prevents excessive pressure drops, and avoids erosion from high velocities.

4. Using the Calculator

Tips: Enter the flow rate in GPM and desired velocity in ft/s (default 5 ft/s for water). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical velocity for water in pipes?
A: For water, 3-5 ft/s is common for supply lines, 5-10 ft/s for drain lines.

Q2: Why is velocity important in pipe sizing?
A: Too high velocity causes erosion and noise; too low velocity may allow sediment buildup.

Q3: How does this relate to pressure drop?
A: Higher velocities generally create greater pressure drops per foot of pipe.

Q4: Can I use this for other liquids?
A: Yes, but adjust the velocity based on the liquid's viscosity and abrasiveness.

Q5: What about pipe material roughness?
A: This calculator assumes smooth pipes. For rough pipes, you may need a larger diameter.