Gas Pipe Sizing Calculator BTU

Pipe Size Formula:

\[ Q = \frac{BTU/hr \times Specific\ Gravity \times Length\ Factor}{Pressure\ Drop} \]

BTU/hr:

BTU/hr

Specific Gravity:

unitless

Length:

feet (ft)

Pressure Drop:

inches water column

Required Pipe Size:

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1. What is Gas Pipe Sizing?

Gas pipe sizing determines the appropriate diameter of gas pipes to safely and efficiently deliver the required amount of gas to appliances based on BTU load, pipe length, and pressure drop considerations.

2. How Does the Calculator Work?

The calculator uses the gas pipe sizing formula:

\[ Q = \frac{BTU/hr \times Specific\ Gravity \times Length\ Factor}{Pressure\ Drop} \]

Where:

\( BTU/hr \) — British thermal units per hour (gas load)
\( Specific\ Gravity \) — Ratio of gas density to air density
\( Length\ Factor \) — Factor based on pipe length and fittings
\( Pressure\ Drop \) — Allowable pressure loss in inches water column

Explanation: The equation calculates the required pipe capacity to handle the gas flow while maintaining adequate pressure for appliance operation.

3. Importance of Proper Pipe Sizing

Details: Correct pipe sizing ensures adequate gas supply to all appliances, prevents pressure drops, maintains safety standards, and ensures efficient system operation without over-sizing pipes unnecessarily.

4. Using the Calculator

Tips: Enter BTU load in BTU/hr, specific gravity (typically 0.60 for natural gas), pipe length in feet, and allowable pressure drop in inches water column. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is specific gravity for natural gas?
A: Natural gas typically has a specific gravity of 0.60, while propane is about 1.52. Check with your gas supplier for exact values.

Q2: What is a typical pressure drop allowance?
A: Most residential systems allow 0.3-0.5 inches water column pressure drop from meter to farthest appliance.

Q3: How does pipe length affect sizing?
A: Longer pipe runs require larger diameters to maintain adequate pressure due to friction losses.

Q4: What about pipe material and fittings?
A: Different materials have different flow characteristics. Fittings add equivalent length that must be considered in calculations.

Q5: Are there code requirements for gas pipe sizing?
A: Yes, local building codes and standards like NFPA 54/International Fuel Gas Code specify requirements for gas pipe sizing and installation.