1. What is a Gas Pipe Size Calculator?

Definition: This calculator estimates the required pipe diameter for gas systems based on flow rate, gas velocity, and a design factor.

Purpose: It helps engineers, plumbers, and HVAC professionals properly size gas piping for safe and efficient operation.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( \text{Size} \) — Pipe diameter (inches)
• \( Q \) — Flow rate (cubic feet per hour, cfh)
• \( \text{Velocity} \) — Gas velocity (feet per second, ft/s)
• \( \text{Factor} \) — Design factor (dimensionless, typically 0.6)

Explanation: The square root of flow rate divided by velocity gives the basic pipe size, which is then adjusted by a safety factor.

3. Importance of Proper Pipe Sizing

Details: Correct pipe sizing ensures adequate gas flow, maintains safe pressures, prevents excessive pressure drops, and meets code requirements.

4. Using the Calculator

Tips: Enter the gas flow rate in cfh, desired gas velocity (default 10 ft/s), and design factor (default 0.6). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical gas velocity in pipes?
A: For natural gas, 10-15 ft/s is common for branch lines, while 20-25 ft/s may be used for main lines.

Q2: Why is the design factor important?
A: It accounts for pressure drop, pipe material, and safety margins. Lower factors (0.5-0.6) are more conservative.

Q3: How do I determine the flow rate (Q)?
A: Sum the BTU ratings of all appliances and convert to cfh (divide by 1000 for natural gas).

Q4: Does this work for all gas types?
A: Yes, but you may need to adjust velocity limits based on gas properties (e.g., propane typically uses lower velocities).

Q5: Should I round up the calculated size?
A: Yes, always round up to the next available standard pipe size for safety and code compliance.