1. What is a GPM Pipe Size 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 appropriately sized pipes 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 to cubic feet)

Explanation: The formula calculates the pipe diameter needed to maintain a specific flow 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, 4-8 ft/s is common (2-5 ft/s for suction lines, 5-10 ft/s for discharge).

Q2: How do I convert pipe diameter to inches?
A: Multiply the result by 12 (1 foot = 12 inches).

Q3: What if I need to calculate for different fluids?
A: Adjust the velocity based on fluid properties (lower for viscous fluids, higher for gases).

Q4: Does this account for pipe material roughness?
A: No, this calculates theoretical diameter. For precise sizing, consider friction losses using more advanced methods.

Q5: What's the 7.481 conversion factor?
A: It converts gallons to cubic feet (1 cubic foot = 7.481 gallons).