What size black pipe is recommended for the first section of piping in a propane system with a maximum load of 340,000 btu/hr and a distance of 80 feet?

The recommendation for using 1 inch black pipe as the first section of piping in a propane system handling a maximum load of 340,000 BTU/hr over a distance of 80 feet is based on ensuring adequate gas flow and pressure maintenance throughout the system.

In gas distribution, the size of the piping directly impacts the flow capacity—larger diameters allow for reduced friction loss, which is crucial for maintaining an adequate pressure at the appliances or endpoints. For a system of this load and pipe length, choosing a diameter that can support the necessary BTU requirements without causing significant pressure drops is critical.

1 inch black pipe is typically used in systems having higher BTU demands, especially when the length of the run is considerable. This helps in minimizing the chances of draft restrictions or inefficiency caused by insufficient gas flow. Systems that are not appropriately sized can lead to appliance performance issues or safety hazards.

The other options do not provide the optimal balance between flow capacity and pressure retention for this scenario, as smaller pipes may not meet the needed gas flow requirements for the specified load effectively, while excessively larger pipes could be unnecessary and lead to higher costs and more complex installation. Thus, the recommendation aligns with the guidelines of NFPA 58, emphasizing