Gas Line Size Calculator

Gas Line Size Formula:

\[ D = \sqrt{ \frac{Q \times L \times S_g}{\Delta P} } \]

Flow Rate (Q):

CFH

Length (L):

Specific Gravity (S_g):

unitless

Pressure Drop (ΔP):

in WC

Diameter (D):

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1. What is the Gas Line Size Calculator?

The Gas Line Size Calculator determines the appropriate diameter for gas piping systems based on flow rate, pipe length, gas specific gravity, and allowable pressure drop. Proper sizing ensures efficient and safe gas delivery to appliances.

2. How Does the Calculator Work?

The calculator uses the gas line sizing formula:

\[ D = \sqrt{ \frac{Q \times L \times S_g}{\Delta P} } \]

Where:

\( D \) — Pipe diameter (inches)
\( Q \) — Flow rate (cubic feet per hour - CFH)
\( L \) — Pipe length (feet)
\( S_g \) — Specific gravity (unitless)
\( \Delta P \) — Pressure drop (inches of water column)

Explanation: This formula calculates the minimum pipe diameter required to deliver the specified gas flow while maintaining the allowable pressure drop throughout the system.

3. Importance of Gas Line Sizing

Details: Proper gas line sizing is critical for ensuring adequate gas pressure at all appliances, preventing safety hazards, optimizing system efficiency, and complying with building codes and standards.

4. Using the Calculator

Tips: Enter flow rate in CFH, pipe length in feet, specific gravity (typically 0.60 for natural gas), and allowable pressure drop in inches WC. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is the typical pressure drop for gas lines?
A: For natural gas systems, typical pressure drop is 0.3-0.5 inches WC for the entire system from meter to appliance.

Q2: What specific gravity should I use for natural gas?
A: Natural gas typically has a specific gravity of 0.60, but check with your local gas provider for exact values.

Q3: How do I account for fittings and elbows?
A: Add equivalent length for fittings - typically add 20-50% to the measured length depending on fitting types and quantity.

Q4: What are common gas pipe materials?
A: Black iron pipe, copper tubing (where allowed), CSST (corrugated stainless steel tubing), and PE (polyethylene) for underground.

Q5: Are there code requirements for gas line sizing?
A: Yes, follow local plumbing codes and NFPA 54 (National Fuel Gas Code) for proper sizing and installation requirements.